use anyhow::{anyhow, Result};
use async_trait::async_trait;
use futures::StreamExt;
use language::{LanguageServerName, LspAdapter, LspAdapterDelegate};
use lsp::LanguageServerBinary;
use node_runtime::NodeRuntime;
use serde_json::json;
use smol::fs;
use std::{
    any::Any,
    ffi::OsString,
    path::{Path, PathBuf},
    sync::Arc,
};
use util::{maybe, ResultExt};

const SERVER_PATH: &str =
    "node_modules/vscode-langservers-extracted/bin/vscode-css-language-server";

fn server_binary_arguments(server_path: &Path) -> Vec<OsString> {
    vec![server_path.into(), "--stdio".into()]
}

pub struct CssLspAdapter {
    node: Arc<dyn NodeRuntime>,
}

impl CssLspAdapter {
    pub fn new(node: Arc<dyn NodeRuntime>) -> Self {
        CssLspAdapter { node }
    }
}

#[async_trait(?Send)]
impl LspAdapter for CssLspAdapter {
    fn name(&self) -> LanguageServerName {
        LanguageServerName("vscode-css-language-server".into())
    }

    async fn fetch_latest_server_version(
        &self,
        _: &dyn LspAdapterDelegate,
    ) -> Result<Box<dyn 'static + Any + Send>> {
        Ok(Box::new(
            self.node
                .npm_package_latest_version("vscode-langservers-extracted")
                .await?,
        ) as Box<_>)
    }

    async fn fetch_server_binary(
        &self,
        latest_version: Box<dyn 'static + Send + Any>,
        container_dir: PathBuf,
        _: &dyn LspAdapterDelegate,
    ) -> Result<LanguageServerBinary> {
        let latest_version = latest_version.downcast::<String>().unwrap();
        let server_path = container_dir.join(SERVER_PATH);
        let package_name = "vscode-langservers-extracted";

        let should_install_language_server = self
            .node
            .should_install_npm_package(package_name, &server_path, &container_dir, &latest_version)
            .await;

        if should_install_language_server {
            self.node
                .npm_install_packages(&container_dir, &[(package_name, latest_version.as_str())])
                .await?;
        }

        Ok(LanguageServerBinary {
            path: self.node.binary_path().await?,
            env: None,
            arguments: server_binary_arguments(&server_path),
        })
    }

    async fn cached_server_binary(
        &self,
        container_dir: PathBuf,
        _: &dyn LspAdapterDelegate,
    ) -> Option<LanguageServerBinary> {
        get_cached_server_binary(container_dir, &*self.node).await
    }

    async fn installation_test_binary(
        &self,
        container_dir: PathBuf,
    ) -> Option<LanguageServerBinary> {
        get_cached_server_binary(container_dir, &*self.node).await
    }

    async fn initialization_options(
        self: Arc<Self>,
        _: &Arc<dyn LspAdapterDelegate>,
    ) -> Result<Option<serde_json::Value>> {
        Ok(Some(json!({
            "provideFormatter": true
        })))
    }
}

async fn get_cached_server_binary(
    container_dir: PathBuf,
    node: &dyn NodeRuntime,
) -> Option<LanguageServerBinary> {
    maybe!(async {
        let mut last_version_dir = None;
        let mut entries = fs::read_dir(&container_dir).await?;
        while let Some(entry) = entries.next().await {
            let entry = entry?;
            if entry.file_type().await?.is_dir() {
                last_version_dir = Some(entry.path());
            }
        }
        let last_version_dir = last_version_dir.ok_or_else(|| anyhow!("no cached binary"))?;
        let server_path = last_version_dir.join(SERVER_PATH);
        if server_path.exists() {
            Ok(LanguageServerBinary {
                path: node.binary_path().await?,
                env: None,
                arguments: server_binary_arguments(&server_path),
            })
        } else {
            Err(anyhow!(
                "missing executable in directory {:?}",
                last_version_dir
            ))
        }
    })
    .await
    .log_err()
}

#[cfg(test)]
mod tests {
    use gpui::{Context, TestAppContext};
    use text::BufferId;
    use unindent::Unindent;

    #[gpui::test]
    async fn test_outline(cx: &mut TestAppContext) {
        let language = crate::language("css", tree_sitter_css::language());

        let text = r#"
            /* Import statement */
            @import './fonts.css';

            /* multiline list of selectors with nesting */
            .test-class,
            div {
                .nested-class {
                    color: red;
                }
            }

            /* descendant selectors */
            .test .descendant {}

            /* pseudo */
            .test:not(:hover) {}

            /* media queries */
            @media screen and (min-width: 3000px) {
                .desktop-class {}
            }
        "#
        .unindent();

        let buffer = cx.new_model(|cx| {
            language::Buffer::new(0, BufferId::new(cx.entity_id().as_u64()).unwrap(), text)
                .with_language(language, cx)
        });
        let outline = buffer.update(cx, |buffer, _| buffer.snapshot().outline(None).unwrap());
        assert_eq!(
            outline
                .items
                .iter()
                .map(|item| (item.text.as_str(), item.depth))
                .collect::<Vec<_>>(),
            &[
                ("@import './fonts.css'", 0),
                (".test-class, div", 0),
                (".nested-class", 1),
                (".test .descendant", 0),
                (".test:not(:hover)", 0),
                ("@media screen and (min-width: 3000px)", 0),
                (".desktop-class", 1),
            ]
        );
    }
}
