use std::io;
use std::net::SocketAddrV4;
use tokio::net::{TcpListener, TcpStream};
use tokio::io::{AsyncReadExt, AsyncWriteExt};

use tauri::{AppHandle, Manager};

mod errors;
use errors::RequestError;


pub async fn serve(addr: SocketAddrV4, app_handle: AppHandle) -> io::Result<()> {
    let listener = TcpListener::bind(&addr).await?;
    println!("Listening on {addr}");
    loop {
        let new_handle = app_handle.app_handle();
        match listener.accept().await {
            Ok((stream, _)) => {
                tokio::spawn(async {
                    if let Err(e) = handle(stream, new_handle).await {
                        eprintln!("{e}");
                    }
                });
            },
            Err(e) => {
                println!("Error accepting connection: {e}");
            }
        }
    }
}


// it doesn't really return a String, we just need to placate the compiler
async fn stall(stream: &mut TcpStream) -> Result<String, tokio::io::Error> {
    let delay = std::time::Duration::from_secs(1);
    loop {
        tokio::time::sleep(delay).await;
        stream.write(b"x").await?;
    }
}


async fn handle(mut stream: TcpStream, app_handle: AppHandle) -> Result<(), RequestError> {
    let mut buf = [0; 8192]; // it's what tokio's BufReader uses
    let mut n = 0;
    loop {
        n += stream.read(&mut buf[n..]).await?;
        if &buf[(n - 4)..n] == b"\r\n\r\n" {break;}
        if n == buf.len() {return Err(RequestError::RequestTooLarge);}
    }

    println!("{}", std::str::from_utf8(&buf).unwrap());

    stream.write(b"HTTP/1.0 200 OK\r\n").await?;
    stream.write(b"Content-Type: application/json\r\n").await?;
    stream.write(b"X-Creddy-delaying-tactic: ").await?;

    let creds = tokio::select!{
        r = stall(&mut stream) => r?, // this will never return Ok, just Err if it can't write to the stream
        c = get_creds(&app_handle) => c?,
    };

    stream.write(b"\r\nContent-Length: ").await?;
    stream.write(creds.as_bytes().len().to_string().as_bytes()).await?;
    stream.write(b"\r\n\r\n").await?;
    stream.write(creds.as_bytes()).await?;
    stream.write(b"\r\n\r\n").await?;
    Ok(())
}


use tokio::io::{stdin, stdout, BufReader, AsyncBufReadExt};
use crate::storage;

use tokio::sync::oneshot;

async fn get_creds(app_handle: &AppHandle) -> io::Result<String> {
    app_handle.emit_all("credentials-request", ()).unwrap();

    // let mut out = stdout();
    // out.write_all(b"Enter passphrase: ").await?;
    // out.flush().await?;

    let (tx, rx) = oneshot::channel();
    app_handle.once_global("passphrase-entered", |event| {
        match event.payload() {
            Some(p) => {tx.send(p.to_string());}
            None => {tx.send("".to_string());} // will fail decryption, we just need to unblock the outer function
        }
    });
    // Error is only returned if the rx is closed/dropped before receiving, which should never happen
    let passphrase = rx.await.unwrap();

    // let mut passphrase = String::new();
    // let mut reader = BufReader::new(stdin());
    // reader.read_line(&mut passphrase).await?;

    Ok(storage::load(&passphrase.trim()))
}