/*
 * Created on Thu Jul 02 2020
 *
 * This file is a part of the source code for the Terrabase database
 * Copyright (c) 2020 Sayan Nandan
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <https://www.gnu.org/licenses/>.
 *
*/

use tokio::io::{AsyncBufReadExt, BufReader};
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::net::{TcpListener, TcpStream};
use tokio::task;

mod coredb;
mod dbnet;
use std::cmp::Ordering;
use std::sync::Arc;
// Internal modules
use libcore::response_packet;
use libcore::terrapipe::{
    Dataframe, QueryMetaframe, QueryMethod, ResponseBytes, ResponseCodes, Version,
    DEF_Q_META_BUFSIZE,
};
const SELF_VERSION: Version = Version(0, 1, 0);

static ADDR: &'static str = "127.0.0.1:2003";

#[tokio::main]
async fn main() {
    let mut listener = TcpListener::bind(ADDR).await.unwrap();
    println!("Server running on terrapipe://127.0.0.1:2003");
    let db = coredb::CoreDB::new();
    loop {
        let handle = db.get_handle();
        let (mut socket, _) = listener.accept().await.unwrap();
        tokio::spawn(async move {
            let mut meta_buffer = String::with_capacity(DEF_Q_META_BUFSIZE);
            let mut reader = BufReader::with_capacity(DEF_Q_META_BUFSIZE, &mut socket);
            reader.read_line(&mut meta_buffer).await.unwrap();
            let mf = match QueryMetaframe::from_buffer(&SELF_VERSION, &meta_buffer) {
                Ok(m) => m,
                Err(e) => {
                    return close_conn_with_error(socket, e.response_bytes(&SELF_VERSION)).await
                }
            };
            let mut data_buffer = vec![0; mf.get_content_size()];
            reader.read(&mut data_buffer).await.unwrap();
            let df = match Dataframe::from_buffer(mf.get_content_size(), data_buffer) {
                Ok(d) => d,
                Err(e) => {
                    return close_conn_with_error(socket, e.response_bytes(&SELF_VERSION)).await
                }
            };
            return execute_query(socket, handle, mf, df).await;
        });
    }
}

async fn close_conn_with_error(mut stream: TcpStream, bytes: Vec<u8>) {
    stream.write_all(&bytes).await.unwrap()
}

async fn execute_query(
    mut stream: TcpStream,
    handle: Arc<coredb::Coretable>,
    mf: QueryMetaframe,
    df: Dataframe,
) {
    let vars = df.deflatten();
    use QueryMethod::*;
    match mf.get_method() {
        GET => {
            let result = match vars.len().cmp(&1) {
                Ordering::Equal => {
                    if let Ok(v) = handle.get(vars[0]) {
                        ResponseCodes::Okay(Some(v.to_string()))
                    } else {
                        ResponseCodes::NotFound
                    }
                }
                _ => ResponseCodes::CorruptDataframe,
            };
            stream
                .write(&result.response_bytes(&SELF_VERSION))
                .await
                .unwrap();
        }
        SET => {
            let result = match vars.len().cmp(&2) {
                Ordering::Equal => match handle.set(vars[0], vars[1]) {
                    Ok(_) => ResponseCodes::Okay(None),
                    Err(e) => e,
                },
                _ => ResponseCodes::CorruptDataframe,
            };
            handle.print_debug_table();
            stream
                .write(&result.response_bytes(&SELF_VERSION))
                .await
                .unwrap();
        }
        UPDATE => {
            let result = match vars.len().cmp(&2) {
                Ordering::Equal => match handle.update(vars[0], vars[1]) {
                    Ok(_) => ResponseCodes::Okay(None),
                    Err(e) => e,
                },
                _ => ResponseCodes::CorruptDataframe,
            };
            handle.print_debug_table();
            stream
                .write(&result.response_bytes(&SELF_VERSION))
                .await
                .unwrap();
        }
        DEL => {
            let result = match vars.len().cmp(&1) {
                Ordering::Equal => match handle.del(vars[0]) {
                    Ok(_) => ResponseCodes::Okay(None),
                    Err(e) => e,
                },
                _ => ResponseCodes::CorruptDataframe,
            };
            handle.print_debug_table();
            stream
                .write(&result.response_bytes(&SELF_VERSION))
                .await
                .unwrap();
        }
    }
}