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

mod encoding;
mod error;
mod id3v1;
mod id3v2;
mod options;

fn parse_options_into(opt: &mut Options) {
    let mut ap = ArgumentParser::new();
    ap.set_description("ID3v2 tag editor/fixer. Incomplete/work-in-progress. Support for ID3v2.3, with partial support of ID3v2.4 (no footer tags supported).");

    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.remove_v1)
        .add_option(&["--remove-v1"], StoreTrue,
                    "Remove any existing ID3v1.* tags.");

    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(tag.to_raw(new_frame)?);
        }

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

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

    Ok(())
}

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

    let open_read = || File::open(&options.file);
    let open_write = || OpenOptions::new().write(true).open(&options.file);

    let mut tag = {
        let (tag, tag_v1) = {
            let mut file = open_read()?;
            let tag = ID3v2::from_stream(&mut file)?;
            let tag_v1 = id3v1::recognise(&mut file)?;
            (tag, tag_v1)
        };

        if options.remove_v1 {
            if let Some(tag_type) = tag_v1 {
                id3v1::remove_tag(&mut open_write()?, tag_type)?;
            } else {
                eprintln!("WARNING: Told to remove ID3v1 tag while none is present.");
            }
        } else {
            if let Some(tag_type) = tag_v1 {
                let descr = match tag_type {
                    id3v1::TagType::TAGv10 => "ID3v1.0",
                    id3v1::TagType::TAGv11 => "ID3v1.1",
                    id3v1::TagType::TAGv12 => "ID3v1.2",
                };
                eprintln!("WARNING: {} tag found at end of file; use --remove-v1 to remove it.", descr);
            }
        }

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

    print_tag(&tag)?;

    // TODO: if -w, then write tags to file (if it fits)
    if options.write {
        let encoded = tag.encode()?;
        open_write()?.write_all(&encoded)?;
        println!("Tag written!");
    }

    Ok(())
}