use log::{info, warn};
use std::{
    fs::{self, File}, io::{BufRead, BufReader}, path::Path, process::{Command, Stdio}
};

pub fn run_flye(fasta_path: &str, tmp_dir: &str, _size: &str) {
    info!("Running Flye for {fasta_path}");
    let flye_bin = "/data/tools/Flye/bin/flye";
    let mut cmd = Command::new(flye_bin)
        .arg("--threads")
        .arg("12")
        // .arg("--keep-haplotypes")
        // .arg("--meta")
        .arg("--min-overlap")
        .arg("1000")
        .arg("--out-dir")
        .arg(tmp_dir)
        .arg("--nano-hq")
        .arg(fasta_path)
        .stderr(Stdio::piped())
        .spawn()
        .expect("Flye failed to start");

    let stderr = cmd.stderr.take().unwrap();
    let reader = BufReader::new(stderr);
    reader
        .lines()
        .map_while(Result::ok)
        .filter(|line| line.contains("ERROR"))
        .for_each(|line| warn!("[FLYE] {line}"));

    cmd.wait().unwrap();
    cmd.kill().unwrap();
}

pub fn read_flye_coverage(path: &str, min_cov: i32, contig_name: &str) -> (usize, usize) {
    use std::io::Read;
    let mut reader = File::open(path).map(flate2::read::GzDecoder::new).unwrap();
    let mut buf = Vec::new();
    reader.read_to_end(&mut buf).unwrap();

    let mut line_acc = Vec::new();
    let mut start = None;
    let mut end = None;
    let mut last_end = 0;
    for b in buf.iter() {
        match b {
            b'\n' => {
                let s = String::from_utf8(line_acc.clone()).unwrap();
                line_acc.clear();
                if !s.starts_with(&format!("{contig_name}\t")) {
                    continue;
                }
                let s = s.split('\t').collect::<Vec<&str>>();
                let cov: i32 = s.get(3).unwrap().parse().unwrap();
                if start.is_none() && cov >= min_cov {
                    let st: i32 = s.get(1).unwrap().parse().unwrap();
                    start = Some(st);
                } else if end.is_none() && start.is_some() && cov < min_cov {
                    let en: i32 = s.get(1).unwrap().parse().unwrap();
                    end = Some(en);
                    break;
                }
                last_end = s.get(2).unwrap().parse().unwrap();
            }
            _ => line_acc.push(*b),
        }
    }
    (start.unwrap() as usize, end.unwrap_or(last_end) as usize)
}

pub fn assemble_flye(reads_path: &str) -> anyhow::Result<Option<Vec<String>>> {
    let min_cov = 2;

    let tmp_dir = format!("/tmp/ass_{}", uuid::Uuid::new_v4());
    fs::create_dir(tmp_dir.clone()).unwrap();

    run_flye(reads_path, &tmp_dir, "10M");

    let contigs_path = format!("{tmp_dir}/assembly.fasta");
    let mut res = None;

    if Path::new(&contigs_path).exists() {
        let assembly_path = format!("{tmp_dir}/assembly.fasta");
        let flye_cov_path = format!("{tmp_dir}/40-polishing/base_coverage.bed.gz");

        let mut reader = File::open(assembly_path)
            .map(BufReader::new)
            .map(noodles_fasta::Reader::new)?;
        let mut contigs = Vec::new();
        for result in reader.records() {
            let record = result?;
            let contig_name = String::from_utf8(record.name().to_vec()).unwrap();
            let (s, e) = read_flye_coverage(&flye_cov_path, min_cov, &contig_name);
            let seq = record.sequence().as_ref();
            let seq = String::from_utf8(seq.to_vec()).unwrap();
            let seq: String = seq[s..e].into();
            contigs.push(seq.clone());
        }
        res = Some(contigs);
    }
    fs::remove_dir_all(tmp_dir)?;
    Ok(res)
}