use serde_aux::field_attributes::deserialize_number_from_string;
use sqlx::postgres::{PgConnectOptions, PgSslMode};
use std::convert::{TryFrom, TryInto};

#[derive(serde::Deserialize, Clone, Debug)]
pub struct Settings {
    pub database: DatabaseSettings,
    pub application: ApplicationSettings,
}

// We are using 127.0.0.1 as our host in address, we are instructing our
// application to only accept connections coming from the same machine. However,
// request from the hose machine which is not seen as local by our Docker image.
//
// Using 0.0.0.0 as host to instruct our application to accept connections from
// any network interface. So using 127.0.0.1 for our local development and set
// it to 0.0.0.0 in our Docker images.
//
#[derive(serde::Deserialize, Clone, Debug)]
pub struct ApplicationSettings {
    #[serde(deserialize_with = "deserialize_number_from_string")]
    pub port: u16,
    pub host: String,
}

#[derive(serde::Deserialize, Clone, Debug)]
pub struct DatabaseSettings {
    pub username: String,
    pub password: String,
    #[serde(deserialize_with = "deserialize_number_from_string")]
    pub port: u16,
    pub host: String,
    pub database_name: String,
    pub require_ssl: bool,
}

impl DatabaseSettings {
    pub fn without_db(&self) -> PgConnectOptions {
        let ssl_mode = if self.require_ssl {
            PgSslMode::Require
        } else {
            PgSslMode::Prefer
        };
        PgConnectOptions::new()
            .host(&self.host)
            .username(&self.username)
            .password(&self.password)
            .port(self.port)
            .ssl_mode(ssl_mode)
    }

    pub fn with_db(&self) -> PgConnectOptions {
        self.without_db().database(&self.database_name)
    }
}

pub fn get_configuration() -> Result<Settings, config::ConfigError> {
    let mut settings = config::Config::default();
    let base_path = std::env::current_dir().expect("Failed to determine the current directory");
    let configuration_dir = base_path.join("configuration");
    settings.merge(config::File::from(configuration_dir.join("base")).required(true))?;

    let environment: Environment = std::env::var("APP_ENVIRONMENT")
        .unwrap_or_else(|_| "local".into())
        .try_into()
        .expect("Failed to parse APP_ENVIRONMENT.");

    settings.merge(config::File::from(configuration_dir.join(environment.as_str())).required(true))?;

    // Add in settings from environment variables (with a prefix of APP and '__' as
    // separator) E.g. `APP_APPLICATION__PORT=5001 would set
    // `Settings.application.port`
    settings.merge(config::Environment::with_prefix("app").separator("__"))?;

    settings.try_into()
}

/// The possible runtime environment for our application.
pub enum Environment {
    Local,
    Production,
}

impl Environment {
    pub fn as_str(&self) -> &'static str {
        match self {
            Environment::Local => "local",
            Environment::Production => "production",
        }
    }
}

impl TryFrom<String> for Environment {
    type Error = String;

    fn try_from(s: String) -> Result<Self, Self::Error> {
        match s.to_lowercase().as_str() {
            "local" => Ok(Self::Local),
            "production" => Ok(Self::Production),
            other => Err(format!(
                "{} is not a supported environment. Use either `local` or `production`.",
                other
            )),
        }
    }
}
