use std::{
    collections::HashMap,
    iter,
    mem::{replace, take},
};

use swc_core::{
    common::{pass::AstNodePath, Mark, Span, Spanned, SyntaxContext, GLOBALS},
    ecma::{
        ast::*,
        atoms::js_word,
        visit::{fields::*, VisitAstPath, VisitWithPath, *},
    },
};
use turbo_tasks::Vc;
use turbopack_core::source::Source;

use super::{ConstantNumber, ConstantValue, ImportMap, JsValue, ObjectPart, WellKnownFunctionKind};
use crate::{analyzer::is_unresolved, utils::unparen};

#[derive(Debug, Clone, Default)]
pub struct EffectsBlock {
    pub effects: Vec<Effect>,
    /// The ast path to the block or expression.
    pub ast_path: Vec<AstParentKind>,
}

impl EffectsBlock {
    pub fn is_empty(&self) -> bool {
        self.effects.is_empty()
    }
}

#[derive(Debug, Clone)]
pub enum ConditionalKind {
    /// The blocks of an `if` statement without an `else` block.
    If { then: EffectsBlock },
    /// The blocks of an `if ... else` statement.
    IfElse {
        then: EffectsBlock,
        r#else: EffectsBlock,
    },
    /// The expressions on the right side of the `?:` operator.
    Ternary {
        then: EffectsBlock,
        r#else: EffectsBlock,
    },
    /// The expression on the right side of the `&&` operator.
    And { expr: EffectsBlock },
    /// The expression on the right side of the `||` operator.
    Or { expr: EffectsBlock },
    /// The expression on the right side of the `??` operator.
    NullishCoalescing { expr: EffectsBlock },
}

impl ConditionalKind {
    /// Normalizes all contained values.
    pub fn normalize(&mut self) {
        match self {
            ConditionalKind::If { then, .. } => {
                for effect in &mut then.effects {
                    effect.normalize();
                }
            }
            ConditionalKind::IfElse { then, r#else, .. }
            | ConditionalKind::Ternary { then, r#else, .. } => {
                for effect in &mut then.effects {
                    effect.normalize();
                }
                for effect in &mut r#else.effects {
                    effect.normalize();
                }
            }
            ConditionalKind::And { expr, .. }
            | ConditionalKind::Or { expr, .. }
            | ConditionalKind::NullishCoalescing { expr, .. } => {
                for effect in &mut expr.effects {
                    effect.normalize();
                }
            }
        }
    }
}

#[derive(Debug, Clone)]
pub enum EffectArg {
    Value(JsValue),
    Closure(JsValue, EffectsBlock),
    Spread,
}

impl EffectArg {
    /// Normalizes all contained values.
    pub fn normalize(&mut self) {
        match self {
            EffectArg::Value(value) => value.normalize(),
            EffectArg::Closure(value, effects) => {
                value.normalize();
                for effect in &mut effects.effects {
                    effect.normalize();
                }
            }
            EffectArg::Spread => {}
        }
    }
}

#[derive(Debug, Clone)]
pub enum Effect {
    /// Some condition which affects which effects might be executed. If the
    /// condition evaluates to some compile-time constant, we can use that
    /// to determine which effects are executed and remove the others.
    Conditional {
        condition: JsValue,
        kind: Box<ConditionalKind>,
        /// The ast path to the condition.
        ast_path: Vec<AstParentKind>,
        span: Span,
        in_try: bool,
    },
    /// A function call.
    Call {
        func: JsValue,
        args: Vec<EffectArg>,
        ast_path: Vec<AstParentKind>,
        span: Span,
        in_try: bool,
    },
    /// A function call of a property of an object.
    MemberCall {
        obj: JsValue,
        prop: JsValue,
        args: Vec<EffectArg>,
        ast_path: Vec<AstParentKind>,
        span: Span,
        in_try: bool,
    },
    /// A property access.
    Member {
        obj: JsValue,
        prop: JsValue,
        ast_path: Vec<AstParentKind>,
        span: Span,
        in_try: bool,
    },
    /// A reference to an imported binding.
    ImportedBinding {
        esm_reference_index: usize,
        export: Option<String>,
        ast_path: Vec<AstParentKind>,
        span: Span,
        in_try: bool,
    },
    /// A reference to a free var access.
    FreeVar {
        var: JsValue,
        ast_path: Vec<AstParentKind>,
        span: Span,
        in_try: bool,
    },
    // TODO ImportMeta should be replaced with Member
    /// A reference to `import.meta`.
    ImportMeta {
        ast_path: Vec<AstParentKind>,
        span: Span,
        in_try: bool,
    },
    /// A reference to `new URL(..., import.meta.url)`.
    Url {
        input: JsValue,
        ast_path: Vec<AstParentKind>,
        span: Span,
        in_try: bool,
    },
}

impl Effect {
    /// Normalizes all contained values.
    pub fn normalize(&mut self) {
        match self {
            Effect::Conditional {
                condition, kind, ..
            } => {
                condition.normalize();
                kind.normalize();
            }
            Effect::Call { func, args, .. } => {
                func.normalize();
                for arg in args.iter_mut() {
                    arg.normalize();
                }
            }
            Effect::MemberCall {
                obj, prop, args, ..
            } => {
                obj.normalize();
                prop.normalize();
                for arg in args.iter_mut() {
                    arg.normalize();
                }
            }
            Effect::Member { obj, prop, .. } => {
                obj.normalize();
                prop.normalize();
            }
            Effect::FreeVar { var, .. } => {
                var.normalize();
            }
            Effect::ImportedBinding { .. } => {}
            Effect::ImportMeta { .. } => {}
            Effect::Url { input, .. } => {
                input.normalize();
            }
        }
    }
}

#[derive(Debug)]
pub struct VarGraph {
    pub values: HashMap<Id, JsValue>,

    pub effects: Vec<Effect>,
}

impl VarGraph {
    pub fn normalize(&mut self) {
        for value in self.values.values_mut() {
            value.normalize();
        }
        for effect in self.effects.iter_mut() {
            effect.normalize();
        }
    }
}

/// You should use same [Mark] for this function and
/// [swc_ecma_transforms_base::resolver::resolver_with_mark]
pub fn create_graph(m: &Program, eval_context: &EvalContext) -> VarGraph {
    let mut graph = VarGraph {
        values: Default::default(),
        effects: Default::default(),
    };

    m.visit_with_path(
        &mut Analyzer {
            data: &mut graph,
            eval_context,
            effects: Default::default(),
            var_decl_kind: Default::default(),
            current_value: Default::default(),
            cur_fn_return_values: Default::default(),
            cur_fn_ident: Default::default(),
        },
        &mut Default::default(),
    );

    graph.normalize();

    graph
}

pub struct EvalContext {
    pub(crate) unresolved_mark: Mark,
    pub(crate) imports: ImportMap,
}

impl EvalContext {
    pub fn new(
        module: &Program,
        unresolved_mark: Mark,
        source: Option<Vc<Box<dyn Source>>>,
    ) -> Self {
        Self {
            unresolved_mark,
            imports: ImportMap::analyze(module, source),
        }
    }

    pub fn is_esm(&self) -> bool {
        self.imports.is_esm()
    }

    fn eval_prop_name(&self, prop: &PropName) -> JsValue {
        match prop {
            PropName::Ident(ident) => ident.sym.clone().into(),
            PropName::Str(str) => str.value.clone().into(),
            PropName::Num(num) => num.value.into(),
            PropName::Computed(ComputedPropName { expr, .. }) => self.eval(expr),
            PropName::BigInt(bigint) => (*bigint.value.clone()).into(),
        }
    }

    fn eval_tpl(&self, e: &Tpl, raw: bool) -> JsValue {
        debug_assert!(e.quasis.len() == e.exprs.len() + 1);

        let mut values = vec![];

        for idx in 0..(e.quasis.len() + e.exprs.len()) {
            if idx % 2 == 0 {
                let idx = idx / 2;
                let e = &e.quasis[idx];

                if raw {
                    values.push(JsValue::from(e.raw.clone()));
                } else {
                    match &e.cooked {
                        Some(v) => {
                            values.push(JsValue::from(v.clone()));
                        }
                        // This is actually unreachable
                        None => return JsValue::unknown_empty(true, ""),
                    }
                }
            } else {
                let idx = idx / 2;
                let e = &e.exprs[idx];

                values.push(self.eval(e));
            }
        }

        if values.len() == 1 {
            return values.into_iter().next().unwrap();
        }

        JsValue::concat(values)
    }

    fn eval_ident(&self, i: &Ident) -> JsValue {
        let id = i.to_id();
        if let Some(imported) = self.imports.get_import(&id) {
            return imported;
        }
        if is_unresolved(i, self.unresolved_mark) {
            JsValue::FreeVar(i.sym.clone())
        } else {
            JsValue::Variable(id)
        }
    }

    pub fn eval(&self, e: &Expr) -> JsValue {
        debug_assert!(
            GLOBALS.is_set(),
            "Eval requires globals from its parsed result"
        );
        match e {
            Expr::Paren(e) => self.eval(&e.expr),
            Expr::Lit(e) => JsValue::Constant(e.clone().into()),
            Expr::Ident(i) => self.eval_ident(i),

            Expr::Unary(UnaryExpr {
                op: op!("!"), arg, ..
            }) => {
                let arg = self.eval(arg);

                JsValue::logical_not(Box::new(arg))
            }

            Expr::Bin(BinExpr {
                op: op!(bin, "+"),
                left,
                right,
                ..
            }) => {
                let l = self.eval(left);
                let r = self.eval(right);

                match (l, r) {
                    (JsValue::Add(c, l), r) => JsValue::Add(
                        c + r.total_nodes(),
                        l.into_iter().chain(iter::once(r)).collect(),
                    ),
                    (l, r) => JsValue::add(vec![l, r]),
                }
            }

            Expr::Bin(BinExpr {
                op: op!("&&"),
                left,
                right,
                ..
            }) => JsValue::logical_and(vec![self.eval(left), self.eval(right)]),

            Expr::Bin(BinExpr {
                op: op!("||"),
                left,
                right,
                ..
            }) => JsValue::logical_or(vec![self.eval(left), self.eval(right)]),

            Expr::Bin(BinExpr {
                op: op!("??"),
                left,
                right,
                ..
            }) => JsValue::nullish_coalescing(vec![self.eval(left), self.eval(right)]),

            Expr::Bin(BinExpr {
                op: op!("=="),
                left,
                right,
                ..
            }) => JsValue::equal(self.eval(left), self.eval(right)),

            Expr::Bin(BinExpr {
                op: op!("!="),
                left,
                right,
                ..
            }) => JsValue::not_equal(self.eval(left), self.eval(right)),

            Expr::Bin(BinExpr {
                op: op!("==="),
                left,
                right,
                ..
            }) => JsValue::strict_equal(self.eval(left), self.eval(right)),

            Expr::Bin(BinExpr {
                op: op!("!=="),
                left,
                right,
                ..
            }) => JsValue::strict_not_equal(self.eval(left), self.eval(right)),

            &Expr::Cond(CondExpr {
                box ref cons,
                box ref alt,
                box ref test,
                ..
            }) => {
                let test = self.eval(test);
                if let Some(truthy) = test.is_truthy() {
                    if truthy {
                        self.eval(cons)
                    } else {
                        self.eval(alt)
                    }
                } else {
                    JsValue::tenary(
                        Box::new(test),
                        Box::new(self.eval(cons)),
                        Box::new(self.eval(alt)),
                    )
                }
            }

            Expr::Tpl(e) => self.eval_tpl(e, false),

            Expr::TaggedTpl(TaggedTpl {
                tag:
                    box Expr::Member(MemberExpr {
                        obj: box Expr::Ident(tag_obj),
                        prop: MemberProp::Ident(tag_prop),
                        ..
                    }),
                tpl,
                ..
            }) => {
                if &*tag_obj.sym == "String"
                    && &*tag_prop.sym == "raw"
                    && is_unresolved(tag_obj, self.unresolved_mark)
                {
                    self.eval_tpl(tpl, true)
                } else {
                    JsValue::unknown_empty(true, "tagged template literal is not supported yet")
                }
            }

            Expr::Fn(expr) => {
                if let Some(ident) = &expr.ident {
                    JsValue::Variable(ident.to_id())
                } else {
                    JsValue::Variable((
                        format!("*anonymous function {}*", expr.function.span.lo.0).into(),
                        SyntaxContext::empty(),
                    ))
                }
            }
            Expr::Arrow(expr) => JsValue::Variable((
                format!("*arrow function {}*", expr.span.lo.0).into(),
                SyntaxContext::empty(),
            )),

            Expr::Await(AwaitExpr { arg, .. }) => self.eval(arg),

            Expr::New(..) => JsValue::unknown_empty(true, "unknown new expression"),

            Expr::Seq(e) => {
                let mut seq = e.exprs.iter().map(|e| self.eval(e)).peekable();
                let mut side_effects = false;
                let mut last = seq.next().unwrap();
                for e in seq {
                    side_effects |= last.has_side_effects();
                    last = e;
                }
                if side_effects {
                    last.make_unknown(true, "sequence with side effects");
                }
                last
            }

            Expr::Member(MemberExpr {
                obj,
                prop: MemberProp::Ident(prop),
                ..
            }) => {
                let obj = self.eval(obj);
                JsValue::member(Box::new(obj), Box::new(prop.sym.clone().into()))
            }

            Expr::Member(MemberExpr {
                obj,
                prop: MemberProp::Computed(computed),
                ..
            }) => {
                let obj = self.eval(obj);
                let prop = self.eval(&computed.expr);
                JsValue::member(Box::new(obj), Box::new(prop))
            }

            Expr::Call(CallExpr {
                callee: Callee::Expr(box callee),
                args,
                ..
            }) => {
                // We currently do not handle spreads.
                if args.iter().any(|arg| arg.spread.is_some()) {
                    return JsValue::unknown_empty(
                        true,
                        "spread in function calls is not supported",
                    );
                }

                let args = args.iter().map(|arg| self.eval(&arg.expr)).collect();
                if let Expr::Member(MemberExpr { obj, prop, .. }) = unparen(callee) {
                    let obj = Box::new(self.eval(obj));
                    let prop = Box::new(match prop {
                        // TODO avoid clone
                        MemberProp::Ident(i) => i.sym.clone().into(),
                        MemberProp::PrivateName(_) => {
                            return JsValue::unknown_empty(
                                false,
                                "private names in function calls is not supported",
                            );
                        }
                        MemberProp::Computed(ComputedPropName { expr, .. }) => self.eval(expr),
                    });
                    JsValue::member_call(obj, prop, args)
                } else {
                    let callee = Box::new(self.eval(callee));

                    JsValue::call(callee, args)
                }
            }

            Expr::Call(CallExpr {
                callee: Callee::Super(_),
                args,
                ..
            }) => {
                // We currently do not handle spreads.
                if args.iter().any(|arg| arg.spread.is_some()) {
                    return JsValue::unknown_empty(
                        true,
                        "spread in function calls is not supported",
                    );
                }

                let args = args.iter().map(|arg| self.eval(&arg.expr)).collect();

                JsValue::super_call(args)
            }

            Expr::Call(CallExpr {
                callee: Callee::Import(_),
                args,
                ..
            }) => {
                // We currently do not handle spreads.
                if args.iter().any(|arg| arg.spread.is_some()) {
                    return JsValue::unknown_empty(true, "spread in import() is not supported");
                }
                let args = args.iter().map(|arg| self.eval(&arg.expr)).collect();

                let callee = Box::new(JsValue::FreeVar(js_word!("import")));

                JsValue::call(callee, args)
            }

            Expr::Array(arr) => {
                if arr.elems.iter().flatten().any(|v| v.spread.is_some()) {
                    return JsValue::unknown_empty(true, "spread is not supported");
                }

                let arr = arr
                    .elems
                    .iter()
                    .map(|e| match e {
                        Some(e) => self.eval(&e.expr),
                        _ => JsValue::FreeVar(js_word!("undefined")),
                    })
                    .collect();
                JsValue::array(arr)
            }

            Expr::Object(obj) => {
                return JsValue::object(
                    obj.props
                        .iter()
                        .map(|prop| match prop {
                            PropOrSpread::Spread(SpreadElement { expr, .. }) => {
                                ObjectPart::Spread(self.eval(expr))
                            }
                            PropOrSpread::Prop(box Prop::KeyValue(KeyValueProp {
                                key,
                                box value,
                            })) => ObjectPart::KeyValue(self.eval_prop_name(key), self.eval(value)),
                            PropOrSpread::Prop(box Prop::Shorthand(ident)) => ObjectPart::KeyValue(
                                ident.sym.clone().into(),
                                self.eval(&Expr::Ident(ident.clone())),
                            ),
                            _ => ObjectPart::Spread(JsValue::unknown_empty(
                                true,
                                "unsupported object part",
                            )),
                        })
                        .collect(),
                )
            }

            _ => JsValue::unknown_empty(true, "unsupported expression"),
        }
    }
}

struct Analyzer<'a> {
    data: &'a mut VarGraph,

    effects: Vec<Effect>,

    eval_context: &'a EvalContext,

    var_decl_kind: Option<VarDeclKind>,

    /// Used for patterns
    current_value: Option<JsValue>,

    /// Return values of the current function.
    ///
    /// This is configured to [Some] by function handlers and filled by the
    /// return statement handler.
    cur_fn_return_values: Option<Vec<JsValue>>,

    cur_fn_ident: u32,
}

pub fn as_parent_path(ast_path: &AstNodePath<AstParentNodeRef<'_>>) -> Vec<AstParentKind> {
    ast_path.iter().map(|n| n.kind()).collect()
}

pub fn as_parent_path_with(
    ast_path: &AstNodePath<AstParentNodeRef<'_>>,
    additional: AstParentKind,
) -> Vec<AstParentKind> {
    ast_path
        .iter()
        .map(|n| n.kind())
        .chain([additional])
        .collect()
}

pub fn is_in_try(ast_path: &AstNodePath<AstParentNodeRef<'_>>) -> bool {
    ast_path
        .iter()
        .rev()
        .find_map(|ast_ref| match ast_ref.kind() {
            AstParentKind::ArrowExpr(ArrowExprField::Body) => Some(false),
            AstParentKind::Function(FunctionField::Body) => Some(false),
            AstParentKind::TryStmt(TryStmtField::Block) => Some(true),
            _ => None,
        })
        .unwrap_or(false)
}

impl Analyzer<'_> {
    fn add_value(&mut self, id: Id, value: JsValue) {
        if let Some(prev) = self.data.values.get_mut(&id) {
            prev.add_alt(value);
        } else {
            self.data.values.insert(id, value);
        }
        // TODO(kdy1): We may need to report an error for this.
        // Variables declared with `var` are hoisted, but using undefined as its
        // value does not seem like a good idea.
    }

    fn add_value_from_expr(&mut self, id: Id, value: &Expr) {
        let value = self.eval_context.eval(value);

        self.add_value(id, value);
    }

    fn add_effect(&mut self, effect: Effect) {
        self.effects.push(effect);
    }

    fn check_iife<'ast: 'r, 'r>(
        &mut self,
        n: &'ast CallExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) -> bool {
        fn unparen<'ast: 'r, 'r, T>(
            expr: &'ast Expr,
            ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
            f: impl FnOnce(&'ast Expr, &mut AstNodePath<AstParentNodeRef<'r>>) -> T,
        ) -> T {
            if let Some(inner_expr) = expr.as_paren() {
                let mut ast_path =
                    ast_path.with_guard(AstParentNodeRef::Expr(expr, ExprField::Paren));
                let mut ast_path = ast_path.with_guard(AstParentNodeRef::ParenExpr(
                    inner_expr,
                    ParenExprField::Expr,
                ));
                unparen(&inner_expr.expr, &mut ast_path, f)
            } else {
                f(expr, ast_path)
            }
        }

        if n.args.iter().any(|arg| arg.spread.is_some()) {
            return false;
        }

        let Some(expr) = n.callee.as_expr() else {
            return false;
        };

        let fn_expr = {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::CallExpr(n, CallExprField::Callee));
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::Callee(&n.callee, CalleeField::Expr));
            unparen(expr, &mut ast_path, |expr, ast_path| match expr {
                Expr::Fn(fn_expr @ FnExpr { function, ident }) => {
                    let mut ast_path =
                        ast_path.with_guard(AstParentNodeRef::Expr(expr, ExprField::Fn));
                    {
                        let mut ast_path = ast_path
                            .with_guard(AstParentNodeRef::FnExpr(fn_expr, FnExprField::Ident));
                        self.visit_opt_ident(ident.as_ref(), &mut ast_path);
                    }

                    {
                        let mut ast_path = ast_path
                            .with_guard(AstParentNodeRef::FnExpr(fn_expr, FnExprField::Function));
                        self.handle_iife_function(function, &mut ast_path, &n.args);
                    }

                    true
                }

                Expr::Arrow(arrow_expr) => {
                    let mut ast_path =
                        ast_path.with_guard(AstParentNodeRef::Expr(expr, ExprField::Arrow));
                    let args = &n.args;
                    self.handle_iife_arrow(arrow_expr, args, &mut ast_path);
                    true
                }
                _ => false,
            })
        };

        if !fn_expr {
            return false;
        }

        let mut ast_path = ast_path.with_guard(AstParentNodeRef::CallExpr(
            n,
            CallExprField::Args(usize::MAX),
        ));

        self.visit_expr_or_spreads(&n.args, &mut ast_path);

        true
    }

    fn handle_iife_arrow<'ast: 'r, 'r>(
        &mut self,
        arrow_expr: &'ast ArrowExpr,
        args: &[ExprOrSpread],
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let ArrowExpr {
            params,
            body,
            is_async: _,
            is_generator: _,
            return_type,
            span: _,
            type_params,
        } = arrow_expr;
        let mut iter = args.iter();
        for (i, param) in params.iter().enumerate() {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::ArrowExpr(
                arrow_expr,
                ArrowExprField::Params(i),
            ));
            if let Some(arg) = iter.next() {
                self.current_value = Some(self.eval_context.eval(&arg.expr));
                self.visit_pat(param, &mut ast_path);
                self.current_value = None;
            } else {
                self.visit_pat(param, &mut ast_path);
            }
        }
        {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::ArrowExpr(
                arrow_expr,
                ArrowExprField::Body,
            ));
            self.visit_block_stmt_or_expr(body, &mut ast_path);
        }

        {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::ArrowExpr(
                arrow_expr,
                ArrowExprField::ReturnType,
            ));
            self.visit_opt_ts_type_ann(return_type.as_ref(), &mut ast_path);
        }

        {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::ArrowExpr(
                arrow_expr,
                ArrowExprField::TypeParams,
            ));
            self.visit_opt_ts_type_param_decl(type_params.as_ref(), &mut ast_path);
        }
    }

    fn handle_iife_function<'ast: 'r, 'r>(
        &mut self,
        function: &'ast Function,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
        args: &[ExprOrSpread],
    ) {
        let mut iter = args.iter();
        let Function {
            body,
            decorators,
            is_async: _,
            is_generator: _,
            params,
            return_type,
            span: _,
            type_params,
        } = function;
        for (i, param) in params.iter().enumerate() {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::Function(
                function,
                FunctionField::Params(i),
            ));
            if let Some(arg) = iter.next() {
                self.current_value = Some(self.eval_context.eval(&arg.expr));
                self.visit_param(param, &mut ast_path);
                self.current_value = None;
            } else {
                self.visit_param(param, &mut ast_path);
            }
        }

        {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::Function(function, FunctionField::Body));

            self.visit_opt_block_stmt(body.as_ref(), &mut ast_path);
        }

        {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::Function(
                function,
                FunctionField::Decorators(usize::MAX),
            ));

            self.visit_decorators(decorators, &mut ast_path);
        }

        {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::Function(
                function,
                FunctionField::ReturnType,
            ));

            self.visit_opt_ts_type_ann(return_type.as_ref(), &mut ast_path);
        }

        {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::Function(
                function,
                FunctionField::TypeParams,
            ));

            self.visit_opt_ts_type_param_decl(type_params.as_ref(), &mut ast_path);
        }
    }

    fn check_call_expr_for_effects<'ast: 'r, 'r>(
        &mut self,
        n: &'ast CallExpr,
        args: Vec<EffectArg>,
        ast_path: &AstNodePath<AstParentNodeRef<'r>>,
    ) {
        match &n.callee {
            Callee::Import(_) => {
                self.add_effect(Effect::Call {
                    func: JsValue::FreeVar(js_word!("import")),
                    args,
                    ast_path: as_parent_path(ast_path),
                    span: n.span(),
                    in_try: is_in_try(ast_path),
                });
            }
            Callee::Expr(box expr) => {
                if let Expr::Member(MemberExpr { obj, prop, .. }) = unparen(expr) {
                    let obj_value = self.eval_context.eval(obj);
                    let prop_value = match prop {
                        // TODO avoid clone
                        MemberProp::Ident(i) => i.sym.clone().into(),
                        MemberProp::PrivateName(_) => {
                            return;
                        }
                        MemberProp::Computed(ComputedPropName { expr, .. }) => {
                            self.eval_context.eval(expr)
                        }
                    };
                    self.add_effect(Effect::MemberCall {
                        obj: obj_value,
                        prop: prop_value,
                        args,
                        ast_path: as_parent_path(ast_path),
                        span: n.span(),
                        in_try: is_in_try(ast_path),
                    });
                } else {
                    let fn_value = self.eval_context.eval(expr);
                    self.add_effect(Effect::Call {
                        func: fn_value,
                        args,
                        ast_path: as_parent_path(ast_path),
                        span: n.span(),
                        in_try: is_in_try(ast_path),
                    });
                }
            }
            Callee::Super(_) => self.add_effect(Effect::Call {
                func: self.eval_context.eval(&Expr::Call(n.clone())),
                args,
                ast_path: as_parent_path(ast_path),
                span: n.span(),
                in_try: is_in_try(ast_path),
            }),
        }
    }

    fn check_member_expr_for_effects<'ast: 'r, 'r>(
        &mut self,
        member_expr: &'ast MemberExpr,
        ast_path: &AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let obj_value = self.eval_context.eval(&member_expr.obj);
        let prop_value = match &member_expr.prop {
            // TODO avoid clone
            MemberProp::Ident(i) => i.sym.clone().into(),
            MemberProp::PrivateName(_) => {
                return;
            }
            MemberProp::Computed(ComputedPropName { expr, .. }) => self.eval_context.eval(expr),
        };
        self.add_effect(Effect::Member {
            obj: obj_value,
            prop: prop_value,
            ast_path: as_parent_path(ast_path),
            span: member_expr.span(),
            in_try: is_in_try(ast_path),
        });
    }

    fn take_return_values(&mut self) -> Box<JsValue> {
        let values = self.cur_fn_return_values.take().unwrap();

        match values.len() {
            0 => Box::new(JsValue::FreeVar(js_word!("undefined"))),
            1 => Box::new(values.into_iter().next().unwrap()),
            _ => Box::new(JsValue::alternatives(values)),
        }
    }
}

impl VisitAstPath for Analyzer<'_> {
    fn visit_assign_expr<'ast: 'r, 'r>(
        &mut self,
        n: &'ast AssignExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::AssignExpr(n, AssignExprField::Left));

            match n.op {
                AssignOp::Assign => {
                    self.current_value = Some(self.eval_context.eval(&n.right));
                    n.left.visit_children_with_path(self, &mut ast_path);
                    self.current_value = None;
                }

                _ => {
                    if let Some(key) = n.left.as_ident() {
                        let value = match n.op {
                            AssignOp::AndAssign | AssignOp::OrAssign | AssignOp::NullishAssign => {
                                let right = self.eval_context.eval(&n.right);
                                // We can handle the right value as alternative to the existing
                                // value
                                Some(right)
                            }
                            AssignOp::AddAssign => {
                                let left = self.eval_context.eval(&Expr::Ident(key.clone()));
                                let right = self.eval_context.eval(&n.right);
                                Some(JsValue::add(vec![left, right]))
                            }
                            _ => Some(JsValue::unknown_empty(true, "unsupported assign operation")),
                        };
                        if let Some(value) = value {
                            self.add_value(key.to_id(), value);
                        }
                    }
                    if n.left.as_ident().is_none() {
                        n.left.visit_children_with_path(self, &mut ast_path);
                    }
                }
            }
        }

        {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::AssignExpr(n, AssignExprField::Right));
            self.visit_expr(&n.right, &mut ast_path);
        }
    }

    fn visit_update_expr<'ast: 'r, 'r>(
        &mut self,
        n: &'ast UpdateExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        if let Some(key) = n.arg.as_ident() {
            self.add_value(
                key.to_id(),
                JsValue::unknown_empty(true, "updated with update expression"),
            );
        }

        let mut ast_path =
            ast_path.with_guard(AstParentNodeRef::UpdateExpr(n, UpdateExprField::Arg));
        self.visit_expr(&n.arg, &mut ast_path);
    }

    fn visit_call_expr<'ast: 'r, 'r>(
        &mut self,
        n: &'ast CallExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        // We handle `define(function (require) {})` here.
        if let Callee::Expr(callee) = &n.callee {
            if n.args.len() == 1 {
                if let Some(require_var_id) = extract_var_from_umd_factory(callee, &n.args) {
                    self.add_value(
                        require_var_id,
                        JsValue::WellKnownFunction(WellKnownFunctionKind::Require),
                    );
                }
            }
        }

        // special behavior of IIFEs
        if !self.check_iife(n, ast_path) {
            {
                let mut ast_path =
                    ast_path.with_guard(AstParentNodeRef::CallExpr(n, CallExprField::Callee));
                n.callee.visit_with_path(self, &mut ast_path);
            }
            let args = n
                .args
                .iter()
                .enumerate()
                .map(|(i, arg)| {
                    let mut ast_path =
                        ast_path.with_guard(AstParentNodeRef::CallExpr(n, CallExprField::Args(i)));
                    if arg.spread.is_none() {
                        let value = self.eval_context.eval(&arg.expr);

                        let block_path = match &*arg.expr {
                            Expr::Fn(FnExpr { .. }) => {
                                let mut path = as_parent_path(&ast_path);
                                path.push(AstParentKind::ExprOrSpread(ExprOrSpreadField::Expr));
                                path.push(AstParentKind::Expr(ExprField::Fn));
                                path.push(AstParentKind::FnExpr(FnExprField::Function));
                                path.push(AstParentKind::Function(FunctionField::Body));
                                Some(path)
                            }
                            Expr::Arrow(ArrowExpr {
                                body: box BlockStmtOrExpr::BlockStmt(_),
                                ..
                            }) => {
                                let mut path = as_parent_path(&ast_path);
                                path.push(AstParentKind::ExprOrSpread(ExprOrSpreadField::Expr));
                                path.push(AstParentKind::Expr(ExprField::Arrow));
                                path.push(AstParentKind::ArrowExpr(ArrowExprField::Body));
                                path.push(AstParentKind::BlockStmtOrExpr(
                                    BlockStmtOrExprField::BlockStmt,
                                ));
                                Some(path)
                            }
                            Expr::Arrow(ArrowExpr {
                                body: box BlockStmtOrExpr::Expr(_),
                                ..
                            }) => {
                                let mut path = as_parent_path(&ast_path);
                                path.push(AstParentKind::ExprOrSpread(ExprOrSpreadField::Expr));
                                path.push(AstParentKind::Expr(ExprField::Arrow));
                                path.push(AstParentKind::ArrowExpr(ArrowExprField::Body));
                                path.push(AstParentKind::BlockStmtOrExpr(
                                    BlockStmtOrExprField::Expr,
                                ));
                                Some(path)
                            }
                            _ => None,
                        };
                        if let Some(path) = block_path {
                            let old_effects = take(&mut self.effects);
                            arg.visit_with_path(self, &mut ast_path);
                            let effects = replace(&mut self.effects, old_effects);
                            EffectArg::Closure(
                                value,
                                EffectsBlock {
                                    effects,
                                    ast_path: path,
                                },
                            )
                        } else {
                            arg.visit_with_path(self, &mut ast_path);
                            EffectArg::Value(value)
                        }
                    } else {
                        arg.visit_with_path(self, &mut ast_path);
                        EffectArg::Spread
                    }
                })
                .collect();
            self.check_call_expr_for_effects(n, args, ast_path);
        }
    }

    fn visit_new_expr<'ast: 'r, 'r>(
        &mut self,
        new_expr: &'ast NewExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        // new URL("path", import.meta.url)
        if let box Expr::Ident(ref callee) = &new_expr.callee {
            if &*callee.sym == "URL" && is_unresolved(callee, self.eval_context.unresolved_mark) {
                if let Some(args) = &new_expr.args {
                    if args.len() == 2 {
                        if let Expr::Member(MemberExpr {
                            obj:
                                box Expr::MetaProp(MetaPropExpr {
                                    kind: MetaPropKind::ImportMeta,
                                    ..
                                }),
                            prop: MemberProp::Ident(prop),
                            ..
                        }) = &*args[1].expr
                        {
                            if &*prop.sym == "url" {
                                self.add_effect(Effect::Url {
                                    input: self.eval_context.eval(&args[0].expr),
                                    ast_path: as_parent_path(ast_path),
                                    span: new_expr.span(),
                                    in_try: is_in_try(ast_path),
                                });
                            }
                        }
                    }
                }
            }
        }
        new_expr.visit_children_with_path(self, ast_path);
    }

    fn visit_member_expr<'ast: 'r, 'r>(
        &mut self,
        member_expr: &'ast MemberExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        self.check_member_expr_for_effects(member_expr, ast_path);
        member_expr.visit_children_with_path(self, ast_path);
    }

    fn visit_expr<'ast: 'r, 'r>(
        &mut self,
        n: &'ast Expr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let old = self.var_decl_kind;
        self.var_decl_kind = None;
        n.visit_children_with_path(self, ast_path);
        self.var_decl_kind = old;
    }

    fn visit_params<'ast: 'r, 'r>(
        &mut self,
        n: &'ast [Param],
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let value = self.current_value.take();
        for (index, p) in n.iter().enumerate() {
            self.current_value = Some(JsValue::Argument(self.cur_fn_ident, index));
            let mut ast_path = ast_path.with_index_guard(index);
            p.visit_children_with_path(self, &mut ast_path);
        }
        self.current_value = value;
    }

    fn visit_param<'ast: 'r, 'r>(
        &mut self,
        n: &'ast Param,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let old = self.var_decl_kind;
        let Param {
            decorators,
            pat,
            span: _,
        } = n;
        self.var_decl_kind = None;
        let value = self.current_value.take();
        {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::Param(
                n,
                ParamField::Decorators(usize::MAX),
            ));
            self.visit_decorators(decorators, &mut ast_path);
        }
        self.current_value = value;
        {
            let mut ast_path = ast_path.with_guard(AstParentNodeRef::Param(n, ParamField::Pat));
            self.visit_pat(pat, &mut ast_path);
        }
        self.current_value = None;
        self.var_decl_kind = old;
    }

    fn visit_fn_decl<'ast: 'r, 'r>(
        &mut self,
        decl: &'ast FnDecl,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let old = replace(
            &mut self.cur_fn_return_values,
            Some(get_fn_init_return_vals(decl.function.body.as_ref())),
        );
        let old_ident = self.cur_fn_ident;
        self.cur_fn_ident = decl.function.span.lo.0;
        decl.visit_children_with_path(self, ast_path);
        let return_value = self.take_return_values();

        self.add_value(
            decl.ident.to_id(),
            JsValue::function(self.cur_fn_ident, return_value),
        );

        self.cur_fn_ident = old_ident;
        self.cur_fn_return_values = old;
    }

    fn visit_fn_expr<'ast: 'r, 'r>(
        &mut self,
        expr: &'ast FnExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let old = replace(
            &mut self.cur_fn_return_values,
            Some(get_fn_init_return_vals(expr.function.body.as_ref())),
        );
        let old_ident = self.cur_fn_ident;
        self.cur_fn_ident = expr.function.span.lo.0;
        expr.visit_children_with_path(self, ast_path);
        let return_value = self.take_return_values();

        if let Some(ident) = &expr.ident {
            self.add_value(
                ident.to_id(),
                JsValue::function(self.cur_fn_ident, return_value),
            );
        } else {
            self.add_value(
                (
                    format!("*anonymous function {}*", expr.function.span.lo.0).into(),
                    SyntaxContext::empty(),
                ),
                JsValue::function(self.cur_fn_ident, return_value),
            );
        }

        self.cur_fn_ident = old_ident;
        self.cur_fn_return_values = old;
    }

    fn visit_arrow_expr<'ast: 'r, 'r>(
        &mut self,
        expr: &'ast ArrowExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let value = match &*expr.body {
            BlockStmtOrExpr::BlockStmt(_block) => {
                let old = replace(
                    &mut self.cur_fn_return_values,
                    Some(get_fn_init_return_vals(Some(_block))),
                );
                let old_ident = self.cur_fn_ident;
                self.cur_fn_ident = expr.span.lo.0;
                expr.visit_children_with_path(self, ast_path);
                let return_value = self.take_return_values();

                let fn_val = JsValue::function(self.cur_fn_ident, return_value);

                self.cur_fn_ident = old_ident;
                self.cur_fn_return_values = old;
                fn_val
            }
            BlockStmtOrExpr::Expr(inner_expr) => {
                let old_ident = self.cur_fn_ident;
                self.cur_fn_ident = expr.span.lo.0;
                expr.visit_children_with_path(self, ast_path);
                let return_value = self.eval_context.eval(inner_expr);

                let fn_val = JsValue::function(self.cur_fn_ident, Box::new(return_value));
                self.cur_fn_ident = old_ident;
                fn_val
            }
        };
        self.add_value(
            (
                format!("*arrow function {}*", expr.span.lo.0).into(),
                SyntaxContext::empty(),
            ),
            value,
        );
    }

    fn visit_class_decl<'ast: 'r, 'r>(
        &mut self,
        decl: &'ast ClassDecl,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        self.add_value_from_expr(
            decl.ident.to_id(),
            // TODO avoid clone
            &Expr::Class(ClassExpr {
                ident: Some(decl.ident.clone()),
                class: decl.class.clone(),
            }),
        );
        decl.visit_children_with_path(self, ast_path);
    }

    fn visit_var_decl<'ast: 'r, 'r>(
        &mut self,
        n: &'ast VarDecl,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let old = self.var_decl_kind;
        self.var_decl_kind = Some(n.kind);
        n.visit_children_with_path(self, ast_path);
        self.var_decl_kind = old;
    }

    fn visit_var_declarator<'ast: 'r, 'r>(
        &mut self,
        n: &'ast VarDeclarator,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        if self.var_decl_kind.is_some() {
            if let Some(init) = &n.init {
                self.current_value = Some(self.eval_context.eval(init));
            }
        }
        {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::VarDeclarator(n, VarDeclaratorField::Name));

            self.visit_pat(&n.name, &mut ast_path);
        }
        self.current_value = None;
        {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::VarDeclarator(n, VarDeclaratorField::Init));

            self.visit_opt_expr(n.init.as_ref(), &mut ast_path);
        }
    }

    fn visit_simple_assign_target<'ast: 'r, 'r>(
        &mut self,
        n: &'ast SimpleAssignTarget,
        ast_path: &mut swc_core::ecma::visit::AstNodePath<'r>,
    ) {
        let value = self.current_value.take();
        if let SimpleAssignTarget::Ident(i) = n {
            self.add_value(
                i.to_id(),
                value.unwrap_or_else(|| {
                    JsValue::unknown(JsValue::Variable(i.to_id()), false, "pattern without value")
                }),
            );
            return;
        }

        n.visit_children_with_path(self, ast_path);
    }

    fn visit_pat<'ast: 'r, 'r>(
        &mut self,
        pat: &'ast Pat,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let value = self.current_value.take();
        match pat {
            Pat::Ident(i) => {
                self.add_value(
                    i.to_id(),
                    value.unwrap_or_else(|| {
                        JsValue::unknown(
                            JsValue::Variable(i.to_id()),
                            false,
                            "pattern without value",
                        )
                    }),
                );
            }

            Pat::Array(arr) => {
                match &value {
                    Some(JsValue::Array { items, .. }) => {
                        let mut ast_path =
                            ast_path.with_guard(AstParentNodeRef::Pat(pat, PatField::Array));
                        for (idx, elem) in arr.elems.iter().enumerate() {
                            self.current_value = items.get(idx).cloned();
                            let mut ast_path = ast_path.with_guard(AstParentNodeRef::ArrayPat(
                                arr,
                                ArrayPatField::Elems(idx),
                            ));
                            elem.visit_with_path(self, &mut ast_path);
                        }

                        // We should not call visit_children_with
                        return;
                    }

                    Some(value) => {
                        let mut ast_path =
                            ast_path.with_guard(AstParentNodeRef::Pat(pat, PatField::Array));
                        for (idx, elem) in arr.elems.iter().enumerate() {
                            self.current_value = Some(JsValue::member(
                                Box::new(value.clone()),
                                Box::new(JsValue::Constant(ConstantValue::Num(ConstantNumber(
                                    idx as f64,
                                )))),
                            ));
                            let mut ast_path = ast_path.with_guard(AstParentNodeRef::ArrayPat(
                                arr,
                                ArrayPatField::Elems(idx),
                            ));
                            elem.visit_with_path(self, &mut ast_path);
                        }
                        // We should not call visit_children_with
                        return;
                    }

                    None => {}
                }
            }

            Pat::Object(obj) => {
                match &value {
                    Some(current_value) => {
                        self.visit_pat_with_value(pat, obj, current_value, ast_path);

                        // We should not call visit_children_with
                        return;
                    }

                    None => {}
                }
            }

            _ => {}
        }
        pat.visit_children_with_path(self, ast_path);
    }

    fn visit_return_stmt<'ast: 'r, 'r>(
        &mut self,
        stmt: &'ast ReturnStmt,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        stmt.visit_children_with_path(self, ast_path);

        if let Some(values) = &mut self.cur_fn_return_values {
            let return_value = stmt
                .arg
                .as_deref()
                .map(|e| self.eval_context.eval(e))
                .unwrap_or(JsValue::FreeVar(js_word!("undefined")));

            values.push(return_value);
        }
    }

    fn visit_ident<'ast: 'r, 'r>(
        &mut self,
        ident: &'ast Ident,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        if !matches!(
            ast_path.last(),
            Some(AstParentNodeRef::Expr(_, ExprField::Ident))
                | Some(AstParentNodeRef::Prop(_, PropField::Shorthand))
        ) {
            return;
        }
        if let Some((esm_reference_index, export)) =
            self.eval_context.imports.get_binding(&ident.to_id())
        {
            self.add_effect(Effect::ImportedBinding {
                esm_reference_index,
                export,
                ast_path: as_parent_path(ast_path),
                span: ident.span(),
                in_try: is_in_try(ast_path),
            })
        } else if is_unresolved(ident, self.eval_context.unresolved_mark) {
            self.add_effect(Effect::FreeVar {
                var: JsValue::FreeVar(ident.sym.clone()),
                ast_path: as_parent_path(ast_path),
                span: ident.span(),
                in_try: is_in_try(ast_path),
            })
        }
    }

    fn visit_meta_prop_expr<'ast: 'r, 'r>(
        &mut self,
        expr: &'ast MetaPropExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        if expr.kind == MetaPropKind::ImportMeta {
            // MetaPropExpr also covers `new.target`. Only consider `import.meta`
            // an effect.
            self.add_effect(Effect::ImportMeta {
                span: expr.span,
                ast_path: as_parent_path(ast_path),
                in_try: is_in_try(ast_path),
            })
        }
    }

    fn visit_program<'ast: 'r, 'r>(
        &mut self,
        program: &'ast Program,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        self.effects = take(&mut self.data.effects);
        program.visit_children_with_path(self, ast_path);
        self.data.effects = take(&mut self.effects);
    }

    fn visit_cond_expr<'ast: 'r, 'r>(
        &mut self,
        expr: &'ast CondExpr,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::CondExpr(expr, CondExprField::Test));
            expr.test.visit_with_path(self, &mut ast_path);
        }

        let prev_effects = take(&mut self.effects);
        let then = {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::CondExpr(expr, CondExprField::Cons));
            expr.cons.visit_with_path(self, &mut ast_path);
            EffectsBlock {
                effects: take(&mut self.effects),
                ast_path: as_parent_path(&ast_path),
            }
        };
        let r#else = {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::CondExpr(expr, CondExprField::Alt));
            expr.alt.visit_with_path(self, &mut ast_path);
            EffectsBlock {
                effects: take(&mut self.effects),
                ast_path: as_parent_path(&ast_path),
            }
        };
        self.effects = prev_effects;

        self.add_conditional_effect(
            &expr.test,
            ast_path,
            AstParentKind::CondExpr(CondExprField::Test),
            expr.span(),
            ConditionalKind::Ternary { then, r#else },
        );
    }

    fn visit_if_stmt<'ast: 'r, 'r>(
        &mut self,
        stmt: &'ast IfStmt,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::IfStmt(stmt, IfStmtField::Test));
            stmt.test.visit_with_path(self, &mut ast_path);
        }
        let prev_effects = take(&mut self.effects);
        let then = {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::IfStmt(stmt, IfStmtField::Cons));
            stmt.cons.visit_with_path(self, &mut ast_path);
            EffectsBlock {
                effects: take(&mut self.effects),
                ast_path: as_parent_path(&ast_path),
            }
        };
        let r#else = stmt
            .alt
            .as_ref()
            .map(|alt| {
                let mut ast_path =
                    ast_path.with_guard(AstParentNodeRef::IfStmt(stmt, IfStmtField::Alt));
                alt.visit_with_path(self, &mut ast_path);
                EffectsBlock {
                    effects: take(&mut self.effects),
                    ast_path: as_parent_path(&ast_path),
                }
            })
            .unwrap_or_default();
        self.effects = prev_effects;
        match (!then.is_empty(), !r#else.is_empty()) {
            (true, false) => {
                self.add_conditional_effect(
                    &stmt.test,
                    ast_path,
                    AstParentKind::IfStmt(IfStmtField::Test),
                    stmt.span(),
                    ConditionalKind::If { then },
                );
            }
            (_, true) => {
                self.add_conditional_effect(
                    &stmt.test,
                    ast_path,
                    AstParentKind::IfStmt(IfStmtField::Test),
                    stmt.span(),
                    ConditionalKind::IfElse { then, r#else },
                );
            }
            (false, false) => {
                // no effects, can be ignored
            }
        }
    }
}

impl<'a> Analyzer<'a> {
    fn add_conditional_effect(
        &mut self,
        test: &Expr,
        ast_path: &AstNodePath<AstParentNodeRef<'_>>,
        ast_kind: AstParentKind,
        span: Span,
        mut cond_kind: ConditionalKind,
    ) {
        let condition = self.eval_context.eval(test);
        if condition.is_unknown() {
            match &mut cond_kind {
                ConditionalKind::If { then } => {
                    self.effects.append(&mut then.effects);
                }
                ConditionalKind::IfElse { then, r#else }
                | ConditionalKind::Ternary { then, r#else } => {
                    self.effects.append(&mut then.effects);
                    self.effects.append(&mut r#else.effects);
                }
                ConditionalKind::And { expr }
                | ConditionalKind::Or { expr }
                | ConditionalKind::NullishCoalescing { expr } => {
                    self.effects.append(&mut expr.effects);
                }
            }
        } else {
            self.add_effect(Effect::Conditional {
                condition,
                kind: Box::new(cond_kind),
                ast_path: as_parent_path_with(ast_path, ast_kind),
                span,
                in_try: is_in_try(ast_path),
            });
        }
    }

    fn visit_pat_with_value<'ast: 'r, 'r>(
        &mut self,
        pat: &'ast Pat,
        obj: &'ast ObjectPat,
        current_value: &JsValue,
        ast_path: &mut AstNodePath<AstParentNodeRef<'r>>,
    ) {
        let mut ast_path = ast_path.with_guard(AstParentNodeRef::Pat(pat, PatField::Object));
        for (i, prop) in obj.props.iter().enumerate() {
            let mut ast_path =
                ast_path.with_guard(AstParentNodeRef::ObjectPat(obj, ObjectPatField::Props(i)));
            match prop {
                ObjectPatProp::KeyValue(kv) => {
                    let mut ast_path = ast_path.with_guard(AstParentNodeRef::ObjectPatProp(
                        prop,
                        ObjectPatPropField::KeyValue,
                    ));
                    let KeyValuePatProp { key, value } = kv;
                    let key_value = self.eval_context.eval_prop_name(key);
                    {
                        let mut ast_path = ast_path.with_guard(AstParentNodeRef::KeyValuePatProp(
                            kv,
                            KeyValuePatPropField::Key,
                        ));
                        key.visit_with_path(self, &mut ast_path);
                    }
                    self.current_value = Some(JsValue::member(
                        Box::new(current_value.clone()),
                        Box::new(key_value),
                    ));
                    {
                        let mut ast_path = ast_path.with_guard(AstParentNodeRef::KeyValuePatProp(
                            kv,
                            KeyValuePatPropField::Value,
                        ));
                        value.visit_with_path(self, &mut ast_path);
                    }
                }
                ObjectPatProp::Assign(assign) => {
                    let mut ast_path = ast_path.with_guard(AstParentNodeRef::ObjectPatProp(
                        prop,
                        ObjectPatPropField::Assign,
                    ));
                    let AssignPatProp { key, value, .. } = assign;
                    let key_value = key.sym.clone().into();
                    {
                        let mut ast_path = ast_path.with_guard(AstParentNodeRef::AssignPatProp(
                            assign,
                            AssignPatPropField::Key,
                        ));
                        key.visit_with_path(self, &mut ast_path);
                    }
                    self.add_value(
                        key.to_id(),
                        if let Some(box value) = value {
                            let value = self.eval_context.eval(value);
                            JsValue::alternatives(vec![
                                JsValue::member(
                                    Box::new(current_value.clone()),
                                    Box::new(key_value),
                                ),
                                value,
                            ])
                        } else {
                            JsValue::member(Box::new(current_value.clone()), Box::new(key_value))
                        },
                    );
                    {
                        let mut ast_path = ast_path.with_guard(AstParentNodeRef::AssignPatProp(
                            assign,
                            AssignPatPropField::Value,
                        ));
                        value.visit_with_path(self, &mut ast_path);
                    }
                }

                _ => prop.visit_with_path(self, &mut ast_path),
            }
        }
    }
}

fn extract_var_from_umd_factory(callee: &Expr, args: &[ExprOrSpread]) -> Option<Id> {
    match unparen(callee) {
        Expr::Ident(Ident { sym, .. }) => {
            if &**sym == "define" {
                if let Expr::Fn(FnExpr { function, .. }) = &*args[0].expr {
                    let params = &*function.params;
                    if params.len() == 1 {
                        if let Pat::Ident(param) = &params[0].pat {
                            if &*param.id.sym == "require" {
                                return Some(param.to_id());
                            }
                        }
                    }
                }
            }
        }

        // umd may use (function (factory){
        //   // Somewhere, define(['require', 'exports'], factory)
        // }(function (require, exports){}))
        //
        // In all module system which has `require`, `require` in the factory function can be
        // treated as a well-known require.
        Expr::Fn(FnExpr { function, .. }) => {
            let params = &*function.params;
            if params.len() == 1 {
                if let Some(FnExpr { function, .. }) =
                    args.first().and_then(|arg| arg.expr.as_fn_expr())
                {
                    let params = &*function.params;
                    if !params.is_empty() {
                        if let Pat::Ident(param) = &params[0].pat {
                            if &*param.id.sym == "require" {
                                return Some(param.to_id());
                            }
                        }
                    }
                }
            }
        }

        _ => {}
    }

    None
}

fn get_fn_init_return_vals(fn_body_stmts: Option<&BlockStmt>) -> Vec<JsValue> {
    let has_final_return_val = match fn_body_stmts {
        Some(fn_body_stmts) => {
            matches!(
                fn_body_stmts.stmts.last(),
                Some(Stmt::Return(ReturnStmt { arg: Some(_), .. }))
            )
        }
        None => false,
    };

    if has_final_return_val {
        vec![]
    } else {
        vec![JsValue::Constant(ConstantValue::Undefined)]
    }
}
