use std::io;
use std::fs::File;
use argparse::{ArgumentParser, Store, StoreTrue, StoreOption};
use crate::error::IntoIOError;
use crate::id3v2::{ID3v2, Frame};
use crate::options::Options;

mod encoding;
mod error;
mod id3v2;
mod options;
mod util;

fn parse_options_into(opt: &mut Options) {
    let mut ap = ArgumentParser::new();
    ap.set_description("ID3v2 tag editor/fixer. Incomplete/work-in-progress.");

    ap.refer(&mut opt.write)
        .add_option(&["-w", "--write"], StoreTrue,
                    "Write updated information instead of just displaying. Unmodified or unknown tags are preserved as-is.");

    ap.refer(&mut opt.latin1_as_utf8)
        .add_option(&["--assume-utf8"], StoreTrue,
                    "Assume that all strings specified in the MP3 as Latin-1 are really UTF-8.");

    ap.refer(&mut opt.set_tags.album) .add_option(&["-A", "--album"],  StoreOption, "Set/replace album");
    ap.refer(&mut opt.set_tags.artist).add_option(&["-a", "--artist"], StoreOption, "Set/replace artist");
    ap.refer(&mut opt.set_tags.title) .add_option(&["-t", "--title"],  StoreOption, "Set/replace title");
    ap.refer(&mut opt.set_tags.track) .add_option(&["-T", "--track"],  StoreOption, "Set/replace track number (num or num/num)");
    ap.refer(&mut opt.set_tags.year)  .add_option(&["-y", "--year"],   StoreOption, "Set/replace year");

    ap.refer(&mut opt.file)
        .required()
        .add_argument("file", Store,
                      "File to operate on (probably a .mp3)");

    ap.parse_args_or_exit();
}

fn parse_options() -> Options {
    let mut options = Default::default();
    parse_options_into(&mut options);
    options
}

fn print_tag(tag: &ID3v2) -> io::Result<()> {
    for frame in &tag.frames {
        match frame.interpret()? {
            Some(Frame::TALB(album))  => println!("Album : '{}'", album),
            Some(Frame::TIT2(title))  => println!("Title : '{}'", title),
            Some(Frame::TPE1(artist)) => println!("Artist: '{}'", artist),
            Some(Frame::TYER(year))   => println!("Year  : '{}'", year),
            Some(Frame::TRCK(track))  => println!("Track : '{}'", track),
            None => {
                println!("Unknown frame: {:?}", frame);
            }
        }
    }
    Ok(())
}

fn modify_tag(tag: &mut ID3v2, new_frame: Frame) -> io::Result<()> {
    let mut indices = Vec::new();
    for (i, frame) in tag.frames.iter().enumerate() {
        if frame.get_id() == new_frame.id() {
            indices.push(i);
        }
    }

    match indices.len() {
        0 => {
            tag.frames.push(new_frame.to_raw()?);
        }

        1 => {
            tag.frames[indices[0]] = new_frame.to_raw()?;
        }

        _ => {
            return Err(format!("Multiple frames of type {} found", new_frame.id()).ioerr());
        }
    }

    Ok(())
}

fn main() -> io::Result<()> {
    let options = parse_options();

    let mut tag = ID3v2::from_stream(&mut File::open(options.file)?)?;
    // println!("{:?}", tag);

    if options.latin1_as_utf8 {
        for frame in &mut tag.frames {
            if let Some(new_frame) =
                    frame.map_string(|s| encoding::from_utf8_mistaken_as_latin1(&s)
                                            .expect("String cannot be encoded in ID3v2 (outside of Unicode BMP)"))? {
                *frame = new_frame;
            }
        }
    }

    if let Some(s) = options.set_tags.album  { modify_tag(&mut tag, Frame::TALB(s))?; }
    if let Some(s) = options.set_tags.artist { modify_tag(&mut tag, Frame::TPE1(s))?; }
    if let Some(s) = options.set_tags.title  { modify_tag(&mut tag, Frame::TIT2(s))?; }
    if let Some(s) = options.set_tags.track  { modify_tag(&mut tag, Frame::TRCK(s))?; }
    if let Some(s) = options.set_tags.year   { modify_tag(&mut tag, Frame::TYER(s))?; }

    print_tag(&tag)?;

    // TODO: if -w, then write tags to file (if it fits)

    Ok(())
}