use anyhow::{Context, Ok, Result};
use rust_htslib::{
    bam,
    bam::{ext::BamRecordExtensions, record, Read, Record},
};

pub fn get_hts_nt_pileup(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    with_next_ins: bool,
) -> Result<Vec<u8>> {
    let stop = start + 1;
    let mut bases = Vec::new();
    bam.fetch((chr, start, stop))?;
    let mut bam_pileup = Vec::new();
    for p in bam.pileup() {
        let pileup = p.context(format!(
            "Can't pilup bam at position {}:{}-{}",
            chr, start, stop
        ))?;
        let position = pileup.pos() as i32;
        if position == start {
            for alignment in pileup.alignments() {
                match alignment.indel() {
                    bam::pileup::Indel::Ins(_len) => bam_pileup.push(b'I'),
                    bam::pileup::Indel::Del(_len) => bam_pileup.push(b'D'),
                    _ => {
                        let record = alignment.record();
                        if record.seq_len() > 0 {
                            if let Some(b) = hts_base_at(&record, start as u32, with_next_ins)? {
                                bases.push(b);
                            }
                        } else {
                            if alignment.is_del() {
                                bases.push(b'D');
                            }
                        }
                    }
                }
            }
        }
    }
    Ok(bases)
}

pub fn hts_base_at(
    record: &rust_htslib::bam::record::Record,
    at_pos: u32,
    with_next_ins: bool,
) -> Result<Option<u8>> {
    use rust_htslib::bam::record::Cigar;

    let cigar = record.cigar();
    let seq = record.seq();
    let pos = cigar.pos() as u32;

    let mut read_i = 0u32;
    let at_pos = at_pos - 1;
    let mut ref_pos = pos;
    if ref_pos > at_pos {
        return Ok(None);
    }

    for (id, op) in cigar.iter().enumerate() {
        let (add_read, add_ref) = match *op {
            Cigar::Match(len) | Cigar::Equal(len) | Cigar::Diff(len) => (len, len),
            Cigar::Ins(len) => (len, 0),
            Cigar::Del(len) => (0, len),
            Cigar::RefSkip(len) => (0, len),
            Cigar::SoftClip(len) => (len, 0),
            Cigar::HardClip(_) | Cigar::Pad(_) => (0, 0),
        };
        // If at the end of the op len and next op is Ins return I
        if with_next_ins && ref_pos + add_read == at_pos + 1 {
            if let Some(Cigar::Ins(_)) = cigar.get(id + 1) {
                return Ok(Some(b'I'));
            }
        }

        if ref_pos + add_ref > at_pos {
            // Handle deletions directly
            if let Cigar::Del(_) = *op {
                return Ok(Some(b'D'));
            } else if let Cigar::RefSkip(_) = op {
                return Ok(None);
            } else {
                let diff = at_pos - ref_pos;
                let p = read_i + diff;
                return Ok(Some(seq[p as usize]));
            }
        }

        read_i += add_read;
        ref_pos += add_ref;
    }
    Ok(None)
}

pub fn get_n_start(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    stop: i32,
) -> Result<usize> {
    bam.fetch((chr, start, stop))?;

    // let mut start_positions = Vec::new();
    let mut n_start = 0;
    for read in bam.records() {
        let record = read.context(format!("eRR"))?;
        let rstart = record.pos() as i32;
        if rstart >= start && rstart < stop {
            if record.mapq() > 40 {
                n_start += 1;
            }
            // start_positions.push(rstart);
        }
    }

    Ok(n_start)
    // Ok(start_positions.len())
}

pub fn get_n_start_end_qual(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    stop: i32,
    mapq: u8,
) -> Result<usize> {
    bam.fetch((chr, start, stop))?;

    // let mut start_positions = Vec::new();
    let mut n_start = 0;
    for read in bam.records() {
        let record = read.context(format!("eRR"))?;
        let rstart = record.pos() as i32;
        let rend = record.reference_end() as i32;
        if rstart >= start && rstart < stop || rend >= start && rend < stop {
            if record.mapq() >= mapq {
                n_start += 1;
            }
        }
    }

    Ok(n_start)
}

pub fn get_start_end_qual(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    stop: i32,
    mapq: u8,
) -> Result<Vec<i32>> {
    bam.fetch((chr, start - 1, stop))?;
    let length = stop - start;
    let mut results = Vec::new();
    results.resize(length as usize, 0);

    for read in bam.records() {
        let record = read.context(format!("Error while parsing record"))?;
        let rstart = record.pos() as i32;
        // let rstart = record.reference_start() as i32;
        let rend = record.reference_end() as i32;

        if rstart >= start && rstart < stop {
            // println!("start {rstart}");
            if record.mapq() >= mapq {
                let index = rstart - start;
                *results.get_mut(index as usize).unwrap() += 1;
            }
        }

        if rend >= start && rend < stop {
            // println!("{rend}");
            if record.mapq() >= mapq {
                let index = rend - start;
                *results.get_mut(index as usize).unwrap() += 1;
            }
        }
    }

    Ok(results)
}

pub fn get_start_end_qual_rec(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    stop: i32,
    mapq: u8,
) -> Result<(Vec<Vec<Record>>, Vec<Vec<Record>>)> {
    bam.fetch((chr, start - 1, stop))?;
    let length = stop - start;
    let mut results_start: Vec<Vec<Record>> = Vec::new();
    results_start.resize(length as usize, vec![]);
    let mut results_end: Vec<Vec<Record>> = Vec::new();
    results_end.resize(length as usize, vec![]);

    for read in bam.records() {
        let record = read.context(format!("Error while parsing record"))?;
        let rstart = record.pos() as i32;
        let rend = record.reference_end() as i32;

        if rstart >= start && rstart < stop {
            if record.mapq() >= mapq {
                let index = rstart - start;
                let u = results_start.get_mut(index as usize).unwrap();
                u.push(record.clone());
            }
        }

        if rend >= start && rend < stop {
            if record.mapq() >= mapq {
                let index = rend - start;
                let u = results_end.get_mut(index as usize).unwrap();
                u.push(record.clone());
            }
        }
    }
    Ok((results_start, results_end))
}

pub fn primary_record(bam_path: &str, record: &Record) -> Option<Record> {
    let mut bam = rust_htslib::bam::IndexedReader::from_path(bam_path).unwrap();
    if record.is_supplementary() {
        let qname = record.qname();
        let mut positions: Vec<(&str, i32)> = Vec::new();
        match record.aux(b"SA") {
            std::result::Result::Ok(v) => match v {
                record::Aux::String(v) => {
                    positions = v
                        .split(";")
                        .filter(|s| s.len() != 0)
                        .map(|s| {
                            let s = s.split(",").take(2).collect::<Vec<&str>>();
                            let chr = *s.get(0).unwrap();
                            let position: i32 = s.get(1).unwrap().parse().unwrap();
                            (chr, position)
                        })
                        .collect();
                }
                _ => (),
            },
            Err(_) => (),
        };
        for (chr, start) in positions {
            bam.fetch((chr, start, start + 1)).unwrap();
            let records = bam.records();
            for record in records {
                let record = record.unwrap();
                // String::from_utf8(record.qname().to_vec()).unwrap().as_str()
                if qname == record.qname() {
                    if !record.is_supplementary() {
                        return Some(record.clone());
                    }
                }
            }
        }
    }
    None
}

pub fn range_depths(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    stop: i32,
) -> Result<Vec<u32>> {
    bam.fetch((chr, start, stop))?;

    let mut depths = vec![0];
    depths.resize((stop - start) as usize, 0);
    for p in bam.pileup() {
        let pileup = p.context(format!("eRR"))?;
        let rstart = pileup.pos() as i32;

        if rstart >= start && rstart < stop {
            // depths.push(pileup.depth());

            let v = depths
                .get_mut((rstart - start) as usize)
                .context(format!("Errrr {}", rstart - start))?;
            *v = pileup.depth();
        } else if rstart >= stop {
            break;
        }
    }

    Ok(depths)
}

pub fn range_depths_qual(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    stop: i32,
    mapq: u8,
) -> Result<Vec<usize>> {
    bam.fetch((chr, start, stop))?;

    let mut depths = vec![0];
    depths.resize((stop - start) as usize, 0);
    for p in bam.pileup() {
        let pileup = p.context(format!("eRR"))?;
        let rstart = pileup.pos() as i32;

        if rstart >= start && rstart < stop {
            let v = depths
                .get_mut((rstart - start) as usize)
                .context(format!("Errrr {}", rstart - start))?;
            *v = pileup
                .alignments()
                .filter(|e| e.record().mapq() >= mapq)
                .count();
        } else if rstart >= stop {
            break;
        }
    }
    Ok(depths)
}

pub fn range_len_qual(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    stop: i32,
    mapq: u8,
) -> Result<Vec<usize>> {
    bam.fetch((chr, start, stop))?;

    let mut depths = vec![0];
    depths.resize((stop - start) as usize, 0);
    for p in bam.pileup() {
        let pileup = p.context(format!("eRR"))?;
        let rstart = pileup.pos() as i32;

        if rstart >= start && rstart < stop {
            let v = depths
                .get_mut((rstart - start) as usize)
                .context(format!("Errrr {}", rstart - start))?;
            *v = pileup
                .alignments()
                .filter(|e| e.record().mapq() >= mapq)
                .map(|e| e.record().seq_len())
                .sum();
        } else if rstart >= stop {
            break;
        }
    }
    Ok(depths)
}

pub fn swap_by_primary(bam_path: &str, records: Vec<Record>) -> Vec<Record> {
    let mut res_records = Vec::new();
    for record in records {
        if let Some(record) = primary_record(bam_path, &record) {
            res_records.push(record);
        } else {
            res_records.push(record);
        }
    }
    res_records
}

pub fn scan_sa(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    stop: i32,
    mapq: u8,
) -> Result<(Vec<Vec<Record>>, Vec<Vec<Record>>)> {
    bam.fetch((chr, start - 1, stop))?;
    let length = stop - start;
    let mut results_start: Vec<Vec<Record>> = Vec::new();
    results_start.resize(length as usize, vec![]);
    let mut results_end: Vec<Vec<Record>> = Vec::new();
    results_end.resize(length as usize, vec![]);

    for read in bam.records() {
        let record = read.context(format!("Error while parsing record"))?;
        let rstart = record.pos() as i32;
        let rend = record.reference_end() as i32;

        if rstart >= start && rstart < stop {
            if record.mapq() >= mapq && record.aux(b"SA").is_ok() {
                
                let index = rstart - start;
                let u = results_start.get_mut(index as usize).unwrap();
                u.push(record.clone());
            }
        }

        if rend >= start && rend < stop && record.aux(b"SA").is_ok() {
            if record.mapq() >= mapq {
                let index = rend - start;
                let u = results_end.get_mut(index as usize).unwrap();
                u.push(record.clone());
            }
        }
    }
    Ok((results_start, results_end))
}

pub fn records_at_base(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    with_next_ins: bool,
) -> Result<Vec<(Record, u8)>> {
    let stop = start + 1;
    let mut bases = Vec::new();
    bam.fetch((chr, start, stop))?;
    let mut bam_pileup = Vec::new();
    for p in bam.pileup() {
        let pileup = p.context(format!(
            "Can't pilup bam at position {}:{}-{}",
            chr, start, stop
        ))?;
        let position = pileup.pos() as i32;
        if position == start {
            for alignment in pileup.alignments() {
                match alignment.indel() {
                    bam::pileup::Indel::Ins(_len) => bam_pileup.push(b'I'),
                    bam::pileup::Indel::Del(_len) => bam_pileup.push(b'D'),
                    _ => {
                        let record = alignment.record();
                        if record.seq_len() > 0 {
                            if let Some(b) = hts_base_at(&record, start as u32, with_next_ins)? {
                                bases.push((record, b));
                            }
                        } else {
                            if alignment.is_del() {
                                bases.push((record, b'D'));
                            }
                        }
                    }
                }
            }
        }
    }
    Ok(bases)
}

pub fn qnames_at_base(
    bam: &mut rust_htslib::bam::IndexedReader,
    chr: &str,
    start: i32,
    with_next_ins: bool,
) -> Result<Vec<(String, u8)>> {
    let stop = start + 1;
    let mut bases = Vec::new();
    bam.fetch((chr, start, stop))?;
    let mut bam_pileup = Vec::new();
    for p in bam.pileup() {
        let pileup = p.context(format!(
            "Can't pilup bam at position {}:{}-{}",
            chr, start, stop
        ))?;
        let position = pileup.pos() as i32;
        if position == start {
            for alignment in pileup.alignments() {
                match alignment.indel() {
                    bam::pileup::Indel::Ins(_len) => bam_pileup.push(b'I'),
                    bam::pileup::Indel::Del(_len) => bam_pileup.push(b'D'),
                    _ => {
                        let record = alignment.record();
                        let qname = String::from_utf8(record.qname().to_vec())?;
                        if record.seq_len() > 0 {
                            if let Some(b) = hts_base_at(&record, start as u32, with_next_ins)? {
                                bases.push((qname, b));
                            }
                        } else {
                            if alignment.is_del() {
                                bases.push((qname, b'D'));
                            }
                        }
                    }
                }
            }
        }
    }
    Ok(bases)
}


#[cfg(test)]
mod tests {
    // Note this useful idiom: importing names from outer (for mod tests) scope.
    use super::*;

    #[test]
    fn test_se() {
        let bam_path = "/data/longreads_basic_pipe/CAMARA/diag/CAMARA_diag_hs1.bam";
        let chr = "chr9";
        let start = 21839796;
        let mapq = 50;

        let mut bam = rust_htslib::bam::IndexedReader::from_path(bam_path).unwrap();

        // let a = get_start_end_qual(&mut bam, chr, start, start + 1, mapq).unwrap();
        // println!("{a:?}");

        let res = get_start_end_qual_rec(&mut bam, chr, start, start + 1, mapq).unwrap();
        let (_, e) = res;
        let res_records = swap_by_primary(bam_path, e.get(0).unwrap().clone());
        println!("{res_records:?}");
        println!("{}", res_records.len());
        assert!(res_records.len() == 12);
    }

    #[test]
    fn test_sa() {
        let bam_path = "/data/longreads_basic_pipe/CAMARA/diag/CAMARA_diag_hs1.bam";
        let chr = "chr9";
        let start = 21839796;
        let mapq = 50;

        let mut bam = rust_htslib::bam::IndexedReader::from_path(bam_path).unwrap();

        let a = get_start_end_qual(&mut bam, chr, start, start + 1, mapq).unwrap().pop().unwrap();

        let (_, e) = get_start_end_qual_rec(&mut bam, chr, start, start + 1, mapq).unwrap();
        let res_records = swap_by_primary(bam_path, e.get(0).unwrap().clone());

        let (_, e) = scan_sa(&mut bam, chr, start, start + 1, mapq).unwrap();
        let res_records_sa = swap_by_primary(bam_path, e.get(0).unwrap().clone());
        assert_eq!(a as usize, res_records.len());
        assert_eq!(a as usize, res_records_sa.len());
    }
}