use std::{io::{BufReader, BufRead}, fs::File, collections::HashMap, cmp, sync::{Mutex}};

use rust_htslib::{bam, bam::{Read, IndexedReader}};
use clap::Parser;
use rand::{thread_rng, seq::SliceRandom};
use indicatif::{ProgressBar, ParallelProgressIterator};
use std::io::Write;
use merge_sequences::*;
use desc_sequence::*;
use rayon::{prelude::*, ThreadPoolBuilder};

#[derive(Parser, Debug)]
#[command(author, version, about, long_about = None)]
struct Args {
    /// bam file path
    #[arg(short, long)]
    bam: String,

    /// positions tsv path (seqname, start, end)
    #[arg(short, long)]
    positions: String,

    /// output tsv path
    #[arg(short, long)]
    output: String,

    /// output tsv path
    #[arg(short, long)]
    genome: String,

    /// output tsv path
    #[arg(short, long)]
    threads: usize,
}

fn main() {
    let args = Args::parse();

    let input_file = File::open(args.positions).unwrap();

    let pb = ProgressBar::new(input_file.metadata().unwrap().len());
    
    let ii = &mut pb.wrap_read(input_file);

    let reader = BufReader::new(ii);

    let mut ranges: HashMap<usize, (String, i64, i64)> = HashMap::new();
    for (n, line) in reader.lines().enumerate() {
        if let Ok(line) = line {
            let mut split = line.split("\t");
            
            ranges.insert(
                n, (
                    split.next().unwrap().to_string(), 
                    split.next().unwrap().parse().unwrap(),
                    split.next().unwrap().parse().unwrap()
                )
            );
        }
    }

    let chunk_size = 100;
    let ranges: Vec<(String, i64, i64)> = ranges.into_iter().map(|(_, e)| e).collect();
    
    let mut file = File::create(args.output).unwrap();
    writeln!(file, "ALT\tn_reads\tdepth").unwrap();
    let mutex = Mutex::new(file);

    let n_chunks = ranges.len() / chunk_size;

    ThreadPoolBuilder::new().num_threads(args.threads).build_global().unwrap();

    ranges.par_chunks(chunk_size)
    .progress_count(n_chunks as u64)
    .for_each(|ranges_chunk| {
        let aligner = BwaAlign::init(&args.genome);
        let mut bam = bam::IndexedReader::from_path(&args.bam).unwrap();
        let mut res: Vec<(String, (i32, i32))> = Vec::new();
        for (seqname, start, end) in ranges_chunk {
            let r = select_reads(
                &mut bam,
                (seqname, *start, *end),
                &aligner
            );
            res.extend(r.iter().map(|(k, v)| (k.to_string(), *v)).collect::<Vec<(String, (i32, i32))>>());
        }

        let mut file = mutex.lock().unwrap();
        res.iter().for_each(|(alt, (n, d))| {
            writeln!(file, "{}\t{}\t{}", alt, n, d).unwrap();
        });

    });
}

fn select_reads(bam: &mut IndexedReader, range: (&str, i64, i64), aligner: &BwaAlign) -> HashMap<String, (i32, i32)> {
    let merge_dist = 5;
    let _ = bam.fetch(range);

    let mut depths: HashMap<u32, u32> = HashMap::new();
    for p in bam.pileup() {
        let pileup = p.unwrap();
        depths.insert(pileup.pos(), pileup.depth());
    }

    let _ = bam.fetch(range);

    let mut seqs = Vec::new();

    for read in bam.records() {
        if let Ok(read) = read {
            let cigar_str: desc_sequence::Cigar = Cigar::new_from_str(&read.cigar().to_string());
            let qname = String::from_utf8(read.qname().to_vec()).unwrap();
            
            for cigar_item in read.cigar().iter() {
                match cigar_item {
                    bam::record::Cigar::Match(_) => (),
                    bam::record::Cigar::Del(_) | bam::record::Cigar::Ins(_) => {
                        let dnas = read.seq().as_bytes();
                        if !dnas.contains(&b'N') { // conversion doesnt work with N TODO
                            let (del, ins) = find_deletion_insertion_ranges(read.pos() as u32, cigar_str.clone(), read.is_reverse());
                            
                            del.into_iter().for_each(|(start, end)| {
                                seqs.push((qname.to_string(), "del".to_string(), start, end, DNAString::new(read.seq().as_bytes())));
                            });

                            ins.into_iter().for_each(|(start, end)| {
                                seqs.push((qname.to_string(), "ins".to_string(), start, end, DNAString::new(read.seq().as_bytes())));
                            });
                        }
                    },
                    bam::record::Cigar::RefSkip(_) => (),
                    bam::record::Cigar::SoftClip(_) => (),
                    bam::record::Cigar::HardClip(_) => (),
                    bam::record::Cigar::Pad(_) => (),
                    bam::record::Cigar::Equal(_) => (),
                    bam::record::Cigar::Diff(_) => (),
                }
            }
        }
    }
    seqs.sort_by(|a, b| {
        a.2.cmp(&b.2)
    });

    let mut grouped: HashMap<i32, (u32, u32, Vec<String>, Vec<DNAString>)> = HashMap::new();

    let mut last_key = None;

    for seq in seqs {
        if let Some(lk) = last_key {
            let last = grouped.get_mut(&lk).unwrap();

            if last.1 + merge_dist >= seq.2 {
                last.1 = cmp::max(last.1, seq.2);
                last.2.push(seq.0);
                last.3.push(seq.4)
            } else {
                let nk = lk + 1;
                last_key = Some(nk);
                grouped.insert(nk, (seq.2, seq.3, vec![seq.0], vec![seq.4]));
                
            }
        } else {
            last_key = Some(0);
            grouped.insert(0, (seq.2, seq.3, vec![seq.0], vec![seq.4]));
        }
    }
 
    let mut results = Vec::new(); 
    for (_k, group) in grouped {
        if group.3.len() > 1 {
            let res = rec_merger(group.3, 15, 2, 1 as i8);

            res.iter().for_each(|s| {
                let r = aligner.get_ref_positions_indel(&s.as_string());
                results.push((group.2.clone(), s.as_string(), r));
            });
        } else if group.3.len() >  0 {
            let u = group.3.first().unwrap();
            
            let r = aligner.get_ref_positions_indel(&u.as_string());
            results.push((group.2.clone(), u.as_string(), r));
        }
    }
    
    let mut indels: HashMap<String, (i32, i32)> = HashMap::new();
    results
    .into_iter()
    .filter(|p| p.0.len() > 1 && p.2.len() >= 1)
    .for_each(|e| {
        e.2.iter().for_each(|em| {
            let k = format!("{}_{}:{}-{}", em.0, em.1, em.2, em.3);
            if let Some(val) = indels.get_mut(&k) {
                val.0 = val.0 + e.0.len() as i32;
            } else {
                let depth = if let Some(v) = depths.get(&(em.2 as u32)) {
                    *v
                } else {
                    0
                };
                
                indels.insert(k, (e.0.len() as i32, depth as i32));
            }
        });
    });

    indels
}

pub fn rec_merger(mut seqs: Vec<DNAString>, kmer_len: usize, max_mismatches: i8, max_consecutive_mismatches: i8) -> Vec<DNAString> {
    let mut n_retry = 0;

    let mut merged = Vec::new();
    let mut last_len = seqs.len();
    loop {
        if last_len <= 1 { break; }

        let tmp = seqs.get(1..).unwrap().to_vec();
        let re = merger(&tmp, seqs.get(0).unwrap(), kmer_len, max_mismatches, max_consecutive_mismatches);
        match re {
            Some(res) => {
                merged.push(res.0.clone());
                seqs = res.1;
            },
            None => {
                match n_retry {
                    0 => seqs.reverse(),
                    _ => seqs.shuffle(&mut thread_rng())
                }
            },
        }
        n_retry += 1;

        if last_len == seqs.len() {
            break;
        } else {
            last_len = seqs.len();
        }
    }
    merged
}


pub fn merger(sequences: &Vec<DNAString>, to_merge: &DNAString, kmer_len: usize, max_mismatches: i8, max_consecutive_mismatches: i8) -> Option<(DNAString, Vec<DNAString>)> {
    let mut to_merge = to_merge.clone();
    let mut merged = Vec::new();

    // try to merge to others seeds
    for (i, seed) in sequences.iter().enumerate() {
        if seed.0.len() >= kmer_len {
            let r = to_merge.merge(seed, kmer_len, max_mismatches, max_consecutive_mismatches);
            match r {
                Ok(_) => {
                    merged.push(i);
                },
                Err(_err) => (),
            }
        }
    }
    
    if merged.len() > 0 {
        Some((
            to_merge,
            sequences.into_iter().enumerate().filter(|(i, _)| !merged.contains(i)).map(|(_, e)| e.clone()).collect::<Vec<DNAString>>()
        ))
    } else {
        None
    }
}