use anyhow::{Context, Ok, Result};
use rust_htslib::{bam, bam::Read};

use average::Mean;
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 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::with_capacity((stop - start) as usize);
    depths.fill(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)
}