import sys
import argparse
import itertools
import warnings
import traceback
import os.path

import HTSeq


class UnknownChrom(Exception):
    pass


def invert_strand(iv):
    iv2 = iv.copy()
    if iv2.strand == "+":
        iv2.strand = "-"
    elif iv2.strand == "-":
        iv2.strand = "+"
    else:
        raise ValueError("Illegal strand")
    return iv2


def count_reads_in_features(sam_filenames, gff_filename,
                            samtype,
                            order, max_buffer_size,
                            stranded, overlap_mode,
                            multimapped_mode,
                            secondary_alignment_mode,
                            supplementary_alignment_mode,
                            feature_type, id_attribute,
                            additional_attributes,
                            quiet, minaqual, samouts):

    def write_to_samout(r, assignment, samoutfile):
        if samoutfile is None:
            return
        if not pe_mode:
            r = (r,)
        for read in r:
            if read is not None:
                read.optional_fields.append(('XF', assignment))
                samoutfile.write(read.get_sam_line() + "\n")

    if samouts != []:
        if len(samouts) != len(sam_filenames):
            raise ValueError('Select the same number of SAM input and output files')
        # Try to open samout files early in case any of them has issues
        for samout in samouts:
            with open(samout, 'w'):
                pass

    # Try to open samfiles to fail early in case any of them is not there
    if (len(sam_filenames) != 1) or (sam_filenames[0] != '-'):
        for sam_filename in sam_filenames:
            with open(sam_filename):
                pass

    # CIGAR match characters (including alignment match, sequence match, and
    # sequence mismatch
    com = ('M', '=', 'X')

    features = HTSeq.GenomicArrayOfSets("auto", stranded != "no")
    gff = HTSeq.GFF_Reader(gff_filename)
    counts = {}
    attributes = {}
    i = 0
    try:
        for f in gff:
            if f.type == feature_type:
                try:
                    feature_id = f.attr[id_attribute]
                except KeyError:
                    raise ValueError("Feature %s does not contain a '%s' attribute" %
                                     (f.name, id_attribute))
                if stranded != "no" and f.iv.strand == ".":
                    raise ValueError("Feature %s at %s does not have strand information but you are "
                                     "running htseq-count in stranded mode. Use '--stranded=no'." %
                                     (f.name, f.iv))
                features[f.iv] += feature_id
                counts[f.attr[id_attribute]] = 0
                attributes[f.attr[id_attribute]] = [
                        f.attr[attr] if attr in f.attr else ''
                        for attr in additional_attributes]
            i += 1
            if i % 100000 == 0 and not quiet:
                sys.stderr.write("%d GFF lines processed.\n" % i)
                sys.stderr.flush()
    except:
        sys.stderr.write(
            "Error occured when processing GFF file (%s):\n" %
            gff.get_line_number_string())
        raise

    if not quiet:
        sys.stderr.write("%d GFF lines processed.\n" % i)
        sys.stderr.flush()

    if len(counts) == 0:
        sys.stderr.write(
            "Warning: No features of type '%s' found.\n" % feature_type)

    if samtype == "sam":
        SAM_or_BAM_Reader = HTSeq.SAM_Reader
    elif samtype == "bam":
        SAM_or_BAM_Reader = HTSeq.BAM_Reader
    else:
        raise ValueError("Unknown input format %s specified." % samtype)

    counts_all = []
    empty_all = []
    ambiguous_all = []
    notaligned_all = []
    lowqual_all = []
    nonunique_all = []
    for isam, (sam_filename) in enumerate(sam_filenames):
        if samouts != []:
            samoutfile = open(samouts[isam], 'w')
        else:
            samoutfile = None

        try:
            if sam_filename == "-":
                read_seq_file = SAM_or_BAM_Reader(sys.stdin)
            else:
                read_seq_file = SAM_or_BAM_Reader(sam_filename)
            read_seq_iter = iter(read_seq_file)
            # Catch empty BAM files
            try:
                first_read = next(read_seq_iter)
                pe_mode = first_read.paired_end
            except:
                first_read = None
                pe_mode = False
            if first_read is not None:
                read_seq = itertools.chain([first_read], read_seq_iter)
            else:
                read_seq = []
        except:
            sys.stderr.write(
                "Error occured when reading beginning of SAM/BAM file.\n")
            raise

        try:
            if pe_mode:
                if ((supplementary_alignment_mode == 'ignore') and
                   (secondary_alignment_mode == 'ignore')):
                    primary_only = True
                else:
                    primary_only = False
                if order == "name":
                    read_seq = HTSeq.pair_SAM_alignments(
                            read_seq,
                            primary_only=primary_only)
                elif order == "pos":
                    read_seq = HTSeq.pair_SAM_alignments_with_buffer(
                            read_seq,
                            max_buffer_size=max_buffer_size,
                            primary_only=primary_only)
                else:
                    raise ValueError("Illegal order specified.")
            empty = 0
            ambiguous = 0
            notaligned = 0
            lowqual = 0
            nonunique = 0
            i = 0
            for r in read_seq:
                if i > 0 and i % 100000 == 0 and not quiet:
                    sys.stderr.write(
                        "%d SAM alignment record%s processed.\n" %
                        (i, "s" if not pe_mode else " pairs"))
                    sys.stderr.flush()

                i += 1
                if not pe_mode:
                    if not r.aligned:
                        notaligned += 1
                        write_to_samout(r, "__not_aligned", samoutfile)
                        continue
                    if ((secondary_alignment_mode == 'ignore') and
                       r.not_primary_alignment):
                        continue
                    if ((supplementary_alignment_mode == 'ignore') and
                       r.supplementary):
                        continue
                    try:
                        if r.optional_field("NH") > 1:
                            nonunique += 1
                            write_to_samout(r, "__alignment_not_unique", samoutfile)
                            if multimapped_mode == 'none':
                                continue
                    except KeyError:
                        pass
                    if r.aQual < minaqual:
                        lowqual += 1
                        write_to_samout(r, "__too_low_aQual", samoutfile)
                        continue
                    if stranded != "reverse":
                        iv_seq = (co.ref_iv for co in r.cigar if co.type in com
                                  and co.size > 0)
                    else:
                        iv_seq = (invert_strand(co.ref_iv)
                                  for co in r.cigar if (co.type in com and
                                                        co.size > 0))
                else:
                    if r[0] is not None and r[0].aligned:
                        if stranded != "reverse":
                            iv_seq = (co.ref_iv for co in r[0].cigar
                                      if co.type in com and co.size > 0)
                        else:
                            iv_seq = (invert_strand(co.ref_iv) for co in r[0].cigar
                                      if co.type in com and co.size > 0)
                    else:
                        iv_seq = tuple()
                    if r[1] is not None and r[1].aligned:
                        if stranded != "reverse":
                            iv_seq = itertools.chain(
                                    iv_seq,
                                    (invert_strand(co.ref_iv) for co in r[1].cigar
                                    if co.type in com and co.size > 0))
                        else:
                            iv_seq = itertools.chain(
                                    iv_seq,
                                    (co.ref_iv for co in r[1].cigar
                                     if co.type in com and co.size > 0))
                    else:
                        if (r[0] is None) or not (r[0].aligned):
                            write_to_samout(r, "__not_aligned", samoutfile)
                            notaligned += 1
                            continue
                    if secondary_alignment_mode == 'ignore':
                        if (r[0] is not None) and r[0].not_primary_alignment:
                            continue
                        elif (r[1] is not None) and r[1].not_primary_alignment:
                            continue
                    if supplementary_alignment_mode == 'ignore':
                        if (r[0] is not None) and r[0].supplementary:
                            continue
                        elif (r[1] is not None) and r[1].supplementary:
                            continue
                    try:
                        if ((r[0] is not None and r[0].optional_field("NH") > 1) or
                           (r[1] is not None and r[1].optional_field("NH") > 1)):
                            nonunique += 1
                            write_to_samout(r, "__alignment_not_unique", samoutfile)
                            if multimapped_mode == 'none':
                                continue
                    except KeyError:
                        pass
                    if ((r[0] and r[0].aQual < minaqual) or
                       (r[1] and r[1].aQual < minaqual)):
                        lowqual += 1
                        write_to_samout(r, "__too_low_aQual", samoutfile)
                        continue

                try:
                    if overlap_mode == "union":
                        fs = set()
                        for iv in iv_seq:
                            if iv.chrom not in features.chrom_vectors:
                                raise UnknownChrom
                            for iv2, fs2 in features[iv].steps():
                                fs = fs.union(fs2)
                    elif overlap_mode in ("intersection-strict",
                                          "intersection-nonempty"):
                        fs = None
                        for iv in iv_seq:
                            if iv.chrom not in features.chrom_vectors:
                                raise UnknownChrom
                            for iv2, fs2 in features[iv].steps():
                                if ((len(fs2) > 0) or
                                   (overlap_mode == "intersection-strict")):
                                    if fs is None:
                                        fs = fs2.copy()
                                    else:
                                        fs = fs.intersection(fs2)
                    else:
                        sys.exit("Illegal overlap mode.")

                    if fs is None or len(fs) == 0:
                        write_to_samout(r, "__no_feature", samoutfile)
                        empty += 1
                    elif len(fs) > 1:
                        write_to_samout(r, "__ambiguous[" + '+'.join(fs) + "]",
                                        samoutfile)
                        ambiguous += 1
                    else:
                        write_to_samout(r, list(fs)[0], samoutfile)

                    if fs is not None and len(fs) > 0:
                        if multimapped_mode == 'none':
                            if len(fs) == 1:
                                counts[list(fs)[0]] += 1
                        elif multimapped_mode == 'all':
                            for fsi in list(fs):
                                counts[fsi] += 1
                        else:
                            sys.exit("Illegal multimap mode.")


                except UnknownChrom:
                    write_to_samout(r, "__no_feature", samoutfile)
                    empty += 1

        except:
            sys.stderr.write(
                "Error occured when processing SAM input (%s):\n" %
                read_seq_file.get_line_number_string())
            raise

        if not quiet:
            sys.stderr.write(
                "%d SAM %s processed.\n" %
                (i, "alignments " if not pe_mode else "alignment pairs"))
            sys.stderr.flush()

        if samoutfile is not None:
            samoutfile.close()

        counts_all.append(counts.copy())
        for fn in counts:
            counts[fn] = 0
        empty_all.append(empty)
        ambiguous_all.append(ambiguous)
        lowqual_all.append(lowqual)
        notaligned_all.append(notaligned)
        nonunique_all.append(nonunique)

    pad = ['' for attr in additional_attributes]
    for fn in sorted(counts.keys()):
        print('\t'.join([fn] + attributes[fn] + [str(c[fn]) for c in counts_all]))
    print('\t'.join(["__no_feature"] + pad + [str(c) for c in empty_all]))
    print('\t'.join(["__ambiguous"] + pad + [str(c) for c in ambiguous_all]))
    print('\t'.join(["__too_low_aQual"] + pad + [str(c) for c in lowqual_all]))
    print('\t'.join(["__not_aligned"] + pad + [str(c) for c in notaligned_all]))
    print('\t'.join(["__alignment_not_unique"] + pad + [str(c) for c in nonunique_all]))


def my_showwarning(message, category, filename, lineno=None, file=None, line=None):
    sys.stderr.write("Warning: %s\n" % message)


def main():

    pa = argparse.ArgumentParser(
        usage="%(prog)s [options] alignment_file gff_file",
        description="This script takes one or more alignment files in SAM/BAM " +
        "format and a feature file in GFF format and calculates for each feature " +
        "the number of reads mapping to it. See " +
        "http://htseq.readthedocs.io/en/master/count.html for details.",
        epilog="Written by Simon Anders (sanders@fs.tum.de), " +
        "European Molecular Biology Laboratory (EMBL). (c) 2010. " +
        "Released under the terms of the GNU General Public License v3. " +
        "Part of the 'HTSeq' framework, version %s." % HTSeq.__version__)

    pa.add_argument(
            "samfilenames", nargs='+', type=str,
            help="Path to the SAM/BAM files containing the mapped reads. " +
            "If '-' is selected, read from standard input")

    pa.add_argument(
            "featuresfilename", type=str,
            help="Path to the file containing the features")

    pa.add_argument(
            "-f", "--format", dest="samtype",
            choices=("sam", "bam"), default="sam",
            help="type of <alignment_file> data, either 'sam' or 'bam' (default: sam)")

    pa.add_argument(
            "-r", "--order", dest="order",
            choices=("pos", "name"), default="name",
            help="'pos' or 'name'. Sorting order of <alignment_file> (default: name). Paired-end sequencing " +
            "data must be sorted either by position or by read name, and the sorting order " +
            "must be specified. Ignored for single-end data.")

    pa.add_argument(
            "--max-reads-in-buffer", dest="max_buffer_size", type=int,
            default=30000000,
            help="When <alignment_file> is paired end sorted by position, " +
            "allow only so many reads to stay in memory until the mates are " +
            "found (raising this number will use more memory). Has no effect " +
            "for single end or paired end sorted by name")

    pa.add_argument(
            "-s", "--stranded", dest="stranded",
            choices=("yes", "no", "reverse"), default="yes",
            help="whether the data is from a strand-specific assay. Specify 'yes', " +
            "'no', or 'reverse' (default: yes). " +
            "'reverse' means 'yes' with reversed strand interpretation")

    pa.add_argument(
            "-a", "--minaqual", type=int, dest="minaqual",
            default=10,
            help="skip all reads with alignment quality lower than the given " +
            "minimum value (default: 10)")

    pa.add_argument(
            "-t", "--type", type=str, dest="featuretype",
            default="exon", help="feature type (3rd column in GFF file) to be used, " +
            "all features of other type are ignored (default, suitable for Ensembl " +
            "GTF files: exon)")

    pa.add_argument(
            "-i", "--idattr", type=str, dest="idattr",
            default="gene_id", help="GFF attribute to be used as feature ID (default, " +
            "suitable for Ensembl GTF files: gene_id)")

    pa.add_argument(
            "--additional-attr", type=str,
            action='append',
            default=[], help="Additional feature attributes (default: none, " +
            "suitable for Ensembl GTF files: gene_name). Use multiple times " +
            "for each different attribute")

    pa.add_argument(
            "-m", "--mode", dest="mode",
            choices=("union", "intersection-strict", "intersection-nonempty"),
            default="union", help="mode to handle reads overlapping more than one feature " +
            "(choices: union, intersection-strict, intersection-nonempty; default: union)")

    pa.add_argument(
            "--nonunique", dest="nonunique", type=str,
            choices=("none", "all"), default="none",
            help="Whether to score reads that are not uniquely aligned " +
            "or ambiguously assigned to features")

    pa.add_argument(
            "--secondary-alignments", dest="secondary_alignments", type=str,
            choices=("score", "ignore"), default="ignore",
            help="Whether to score secondary alignments (0x100 flag)")

    pa.add_argument(
            "--supplementary-alignments", dest="supplementary_alignments", type=str,
            choices=("score", "ignore"), default="ignore",
            help="Whether to score supplementary alignments (0x800 flag)")

    pa.add_argument(
            "-o", "--samout", type=str, dest="samouts",
            action='append',
            default=[], help="write out all SAM alignment records into " +
            "SAM files (one per input file needed), annotating each line " +
            "with its feature assignment (as an optional field with tag 'XF')")

    pa.add_argument(
            "-q", "--quiet", action="store_true", dest="quiet",
            help="suppress progress report")  # and warnings" )

    args = pa.parse_args()

    warnings.showwarning = my_showwarning
    try:
        count_reads_in_features(
                args.samfilenames,
                args.featuresfilename,
                args.samtype,
                args.order,
                args.max_buffer_size,
                args.stranded,
                args.mode,
                args.nonunique,
                args.secondary_alignments,
                args.supplementary_alignments,
                args.featuretype,
                args.idattr,
                args.additional_attr,
                args.quiet,
                args.minaqual,
                args.samouts)
    except:
        sys.stderr.write("  %s\n" % str(sys.exc_info()[1]))
        sys.stderr.write("  [Exception type: %s, raised in %s:%d]\n" %
                         (sys.exc_info()[1].__class__.__name__,
                          os.path.basename(traceback.extract_tb(
                              sys.exc_info()[2])[-1][0]),
                          traceback.extract_tb(sys.exc_info()[2])[-1][1]))
        sys.exit(1)


if __name__ == "__main__":
    main()
