//! This module implements the database connection actor.

use actix::prelude::*;
use diesel;
use diesel::prelude::*;
use diesel::r2d2::{Pool, ConnectionManager};
use models::*;
use errors::{ConverseError, Result};

/// The DB actor itself. Several of these will be run in parallel by
/// `SyncArbiter`.
pub struct DbExecutor(pub Pool<ConnectionManager<PgConnection>>);

impl Actor for DbExecutor {
    type Context = SyncContext<Self>;
}

/// Message used to request a list of threads.
/// TODO: This should support page numbers.
pub struct ListThreads;

impl Message for ListThreads {
    type Result = Result<Vec<Thread>>;
}

impl Handler<ListThreads> for DbExecutor {
    type Result = <ListThreads as Message>::Result;

    fn handle(&mut self, _: ListThreads, _: &mut Self::Context) -> Self::Result {
        use schema::threads::dsl::*;

        let conn = self.0.get()?;
        let results = threads
            .order(posted.desc())
            .load::<Thread>(&conn)?;
        Ok(results)
    }
}

/// Message used to fetch a specific thread. Returns the thread and
/// its posts.
pub struct GetThread(pub i32);

impl Message for GetThread {
    type Result = Result<(Thread, Vec<Post>)>;
}

impl Handler<GetThread> for DbExecutor {
    type Result = <GetThread as Message>::Result;

    fn handle(&mut self, msg: GetThread, _: &mut Self::Context) -> Self::Result {
        use schema::threads::dsl::*;

        let conn = self.0.get()?;
        let thread_result: Thread = threads
            .find(msg.0).first(&conn)?;

        let post_list = Post::belonging_to(&thread_result).load::<Post>(&conn)?;

        Ok((thread_result, post_list))
    }
}

/// Message used to create a new thread
pub struct CreateThread {
    pub new_thread: NewThread,
    pub body: String,
}

impl Message for CreateThread {
    type Result = Result<Thread>;
}

impl Handler<CreateThread> for DbExecutor {
    type Result = <CreateThread as Message>::Result;

    fn handle(&mut self, msg: CreateThread, _: &mut Self::Context) -> Self::Result {
        use schema::threads;
        use schema::posts;

        let conn = self.0.get()?;

        conn.transaction::<Thread, ConverseError, _>(|| {
            // First insert the thread structure itself
            let thread: Thread = diesel::insert_into(threads::table)
                .values(&msg.new_thread)
                .get_result(&conn)?;

            // ... then create the first post in the thread.
            let new_post = NewPost {
                thread_id: thread.id,
                body: msg.body,
                author_name: msg.new_thread.author_name.clone(),
                author_email: msg.new_thread.author_email.clone(),
            };

            diesel::insert_into(posts::table)
                .values(&new_post)
                .execute(&conn)?;

            Ok(thread)
        })
    }
}

/// Message used to create a new reply
pub struct CreatePost(pub NewPost);

impl Message for CreatePost {
    type Result = Result<Post>;
}

impl Handler<CreatePost> for DbExecutor {
    type Result = <CreatePost as Message>::Result;

    fn handle(&mut self, msg: CreatePost, _: &mut Self::Context) -> Self::Result {
        use schema::posts;

        let conn = self.0.get()?;

        Ok(diesel::insert_into(posts::table)
           .values(&msg.0)
           .get_result(&conn)?)
    }
}