use serenity::voice::ffmpeg;
use std::process::{Command, Output, Stdio};
use std::str::from_utf8;

use player::Song;

const FIRST_LOAD_PREFIX: &str = "[download] Destination:";
const RELOAD_SUFFIX: &str = " has already been downloaded";
const PREFIX: &str = "[download] ";

pub fn convert_file_name(file: String) -> String {
    let mut file = file.to_string();
    let file_name_len = file.len();

    let mut file_without_suffix = if file.ends_with(".webm") {
        file.split_off(file_name_len - 5);
        file
    } else {
        file
    };

    let file_without_id = match file_without_suffix.rfind("-") {
        Some(minus_pos) => {
            file_without_suffix.split_off(minus_pos);
            file_without_suffix
        }
        None => file_without_suffix,
    };

    file_without_id
}

fn convert_output(out: &Output) -> Result<Vec<String>, String> {
    match from_utf8(out.stdout.as_slice()) {
        Ok(string) => {
            let lines = string.split("\n");

            let mut files = Vec::new();

            for line in lines {
                if !line.is_empty() {
                    let mut line = line.to_string();
                    let line_len = line.len();

                    if line.starts_with(FIRST_LOAD_PREFIX) {
                        let file_name = line.split_off(FIRST_LOAD_PREFIX.len());
                        files.push(file_name.trim().to_string());
                    } else if line.ends_with(RELOAD_SUFFIX) {
                        line.split_off(line_len - RELOAD_SUFFIX.len());
                        let file_name = line.split_off(PREFIX.len());
                        files.push(file_name.trim().to_string());
                    }
                }
            }   

            let mut mp3s = Vec::new();

            for file in files {
                mp3s.push(str::replace(file.as_str(), ".webm", ".mp3").to_string());
            }

            Ok(mp3s)
        }

        Err(_) => Err("error converting output".to_string()),
    }
}

pub fn youtube_dl(uri: &str) -> Result<Vec<Song>, String> {
    let args = ["-x", "--audio-format", "mp3", "--audio-quality", "5", uri];

    let out = match Command::new("youtube-dl")
        .args(&args)
        .stdin(Stdio::null())
        .output()
    {
        Ok(out) => out,
        Err(_) => return Err("youtube-dl error".to_string()),
    };

    if !out.status.success() {
        return Err("shell error".to_string());
    }

    let files = check_result!(convert_output(&out));

    for file in &files {
        println!("file: {}", file);
    }

    let mut ffmpegs = Vec::new();

    for file in files {
        match ffmpeg(&file) {
            Ok(mpeg) => ffmpegs.push(Song {
                source: mpeg,
                name: file,
            }),
            Err(_) => return Err("ffmpeg error".to_string()),
        }
    }

    Ok(ffmpegs)
}