use flowy_database::{
    query_dsl::*,
    schema::{user_table, user_table::dsl},
    DBConnection,
    ExpressionMethods,
    UserDatabaseConnection,
};
use flowy_infra::kv::KVStore;
use lazy_static::lazy_static;
use std::sync::RwLock;

use crate::{
    entities::{SignInParams, SignUpParams, UpdateUserParams, UserDetail},
    errors::{ErrorBuilder, UserError, UserErrorCode},
    services::user_session::{database::UserDB, user_server::UserServer},
    sql_tables::{User, UserChangeset},
};

pub struct UserSessionConfig {
    root_dir: String,
}

impl UserSessionConfig {
    pub fn new(root_dir: &str) -> Self {
        Self {
            root_dir: root_dir.to_owned(),
        }
    }
}

pub struct UserSession {
    database: UserDB,
    config: UserSessionConfig,
    server: Box<dyn UserServer + Send + Sync>,
}

impl UserSession {
    pub fn new<R>(config: UserSessionConfig, server: R) -> Self
    where
        R: 'static + UserServer + Send + Sync,
    {
        let db = UserDB::new(&config.root_dir);
        Self {
            database: db,
            config,
            server: Box::new(server),
        }
    }

    pub async fn sign_in(&self, params: SignInParams) -> Result<User, UserError> {
        let user = self.server.sign_in(params)?;
        let _ = set_current_user_id(Some(user.id.clone()))?;
        self.save_user(user)
    }

    pub async fn sign_up(&self, params: SignUpParams) -> Result<User, UserError> {
        let user = self.server.sign_up(params)?;
        let _ = set_current_user_id(Some(user.id.clone()))?;
        self.save_user(user)
    }

    pub async fn sign_out(&self) -> Result<(), UserError> {
        let user_id = self.current_user_id()?;
        let conn = self.get_db_connection()?;
        let _ = diesel::delete(dsl::user_table.filter(dsl::id.eq(&user_id))).execute(&*conn)?;

        match self.server.sign_out(&user_id) {
            Ok(_) => {},
            Err(_) => {},
        }
        let _ = self.database.close_user_db()?;
        let _ = set_current_user_id(None)?;

        Ok(())
    }

    pub async fn update_user(&self, params: UpdateUserParams) -> Result<UserDetail, UserError> {
        let changeset = UserChangeset::new(params);
        let conn = self.get_db_connection()?;
        diesel_update_table!(user_table, changeset, conn);

        let user_detail = self.current_user_detail()?;
        Ok(user_detail)
    }

    pub fn current_user_detail(&self) -> Result<UserDetail, UserError> {
        let user_id = self.current_user_id()?;
        let conn = self.get_db_connection()?;

        let user = dsl::user_table
            .filter(user_table::id.eq(&user_id))
            .first::<User>(&*conn)?;

        match self.server.get_user_info(&user_id) {
            Ok(_user_detail) => {
                // TODO: post latest user_detail to upper layer
            },
            Err(_e) => {
                // log::debug!("Get user details failed. {:?}", e);
            },
        }

        Ok(UserDetail::from(user))
    }

    pub fn get_db_connection(&self) -> Result<DBConnection, UserError> {
        let user_id = get_current_user_id()?;
        self.database.get_connection(&user_id)
    }

    #[allow(dead_code)]
    pub fn get_current_workspace(&self) -> Result<String, UserError> {
        let user_id = get_current_user_id()?;
        let conn = self.get_db_connection()?;

        let workspace = dsl::user_table
            .filter(user_table::id.eq(&user_id))
            .select(user_table::workspace)
            .first::<String>(&*conn)?;

        Ok(workspace)
    }
}

impl UserSession {
    fn save_user(&self, user: User) -> Result<User, UserError> {
        let conn = self.get_db_connection()?;
        let _ = diesel::insert_into(user_table::table)
            .values(user.clone())
            .execute(&*conn)?;

        Ok(user)
    }

    fn current_user_id(&self) -> Result<String, UserError> {
        match KVStore::get_str(USER_ID_DISK_CACHE_KEY) {
            None => Err(ErrorBuilder::new(UserErrorCode::UserNotLoginYet).build()),
            Some(user_id) => Ok(user_id),
        }
    }
}

impl UserDatabaseConnection for UserSession {
    fn get_connection(&self) -> Result<DBConnection, String> {
        self.get_db_connection().map_err(|e| format!("{:?}", e))
    }
}

const USER_ID_DISK_CACHE_KEY: &str = "user_id";
lazy_static! {
    pub static ref CURRENT_USER_ID: RwLock<Option<String>> = RwLock::new(None);
}

pub(crate) fn get_current_user_id() -> Result<String, UserError> {
    let read_guard = CURRENT_USER_ID.read().map_err(|e| {
        ErrorBuilder::new(UserErrorCode::ReadCurrentIdFailed)
            .error(e)
            .build()
    })?;

    let mut user_id = (*read_guard).clone();
    // explicitly drop the read_guard in case of dead lock
    drop(read_guard);

    if user_id.is_none() {
        user_id = KVStore::get_str(USER_ID_DISK_CACHE_KEY);
        *(CURRENT_USER_ID.write().unwrap()) = user_id.clone();
    }

    if user_id.is_none() {
        return Err(ErrorBuilder::new(UserErrorCode::UserNotLoginYet).build());
    }

    match user_id {
        None => Err(ErrorBuilder::new(UserErrorCode::UserNotLoginYet).build()),
        Some(user_id) => Ok(user_id),
    }
}

pub(crate) fn set_current_user_id(user_id: Option<String>) -> Result<(), UserError> {
    KVStore::set_str(
        USER_ID_DISK_CACHE_KEY,
        user_id.clone().unwrap_or("".to_owned()),
    );

    let mut current_user_id = CURRENT_USER_ID.write().map_err(|e| {
        ErrorBuilder::new(UserErrorCode::WriteCurrentIdFailed)
            .error(e)
            .build()
    })?;
    *current_user_id = user_id;
    Ok(())
}