use std::{
    fs,
    io::{BufRead, BufReader},
};

use torque_tracker_engine::{
    file::{InFilePtr, SansIO, header::ImpulseHeader, pattern::PatternParser},
    project::song::Song,
};

/// Move the Read Cursor to the value of the file ptr
pub fn move_to_ptr<S: std::io::Seek>(ptr: InFilePtr, seeker: &mut S) -> Result<(), std::io::Error> {
    seeker
        .seek(std::io::SeekFrom::Start(ptr.get().get().into()))
        .map(|_| ())
}

fn load_file(path: &str) -> Song {
    let file = fs::File::open(path).unwrap();

    let mut buf = BufReader::new(file);
    let mut header_parser =
        ImpulseHeader::parse(buf.fill_buf().unwrap().first_chunk().unwrap()).unwrap();
    buf.consume(ImpulseHeader::BASE_SIZE);

    let header = loop {
        match header_parser.parse(buf.fill_buf().unwrap()) {
            SansIO::Finished(res, amount) => {
                buf.consume(amount);
                break res;
            }
            SansIO::Pending(amount) => buf.consume(amount),
        }
    };

    let mut song = Song::default();
    header.copy_values_into_song(&mut song);

    for (idx, ptr) in header
        .pattern_offsets
        .iter()
        // number the slots
        .enumerate()
        // filter out empty slots, while keeping the numbering the same
        .flat_map(|(idx, ptr)| ptr.map(|ptr| (idx, ptr)))
    {
        move_to_ptr(ptr, &mut buf).unwrap();
        let mut parser =
            PatternParser::new(buf.fill_buf().unwrap().first_chunk().unwrap()).unwrap();
        buf.consume(PatternParser::HEADER_SIZE);
        let pattern = loop {
            match parser.parse(buf.fill_buf().unwrap()) {
                SansIO::Finished(res, amount) => {
                    buf.consume(amount);
                    break res;
                }
                SansIO::Pending(amount) => buf.consume(amount),
            }
        };
        song.patterns[idx] = pattern;
    }

    song
}

fn main() {
    let path = std::env::args().nth(1).unwrap();
    println!("path: {path}");
    let file = std::fs::File::open(&path).unwrap();
    println!("file len: {}", file.metadata().unwrap().len());

    let song = load_file(&path);
    print!("{:?}", song)
}