#!/usr/bin/env python

import re
import sys
import xml.etree.cElementTree as ElementTree


def __main__():
    source = sys.argv[1]
    hspTags = ["Hsp_bit-score",
               "Hsp_evalue",
               "Hsp_query-from",
               "Hsp_query-to",
               "Hsp_hit-from",
               "Hsp_hit-to",
               "Hsp_query-frame",
               "Hsp_hit-frame",
               "Hsp_identity",
               "Hsp_align-len",
               "Hsp_qseq",
               "Hsp_hseq",
               "Hsp_midline"]

    # get an iterable
    try:
        context = ElementTree.iterparse(source, events=("start", "end"))
    except Exception:
        sys.exit("Invalid data format.")
    # turn it into an iterator
    context = iter(context)
    # get the root element
    try:
        event, root = next(context)
    except Exception:
        sys.exit("Invalid data format.")

    with open(sys.argv[2], 'w') as outfile:
        try:
            for event, elem in context:
                # for every <Iteration> tag
                if event == "end" and elem.tag == "Iteration":
                    query = elem.findtext("Iteration_query-def")
                    qLen = elem.findtext("Iteration_query-len")
                    # for every <Hit> within <Iteration>
                    for hit in elem.findall("Iteration_hits/Hit"):
                        subject = hit.findtext("Hit_id")
                        if re.search('^gi', subject):
                            subject = subject.split('|')[1]
                        sLen = hit.findtext("Hit_len")
                        # for every <Hsp> within <Hit>
                        for hsp in hit.findall("Hit_hsps/Hsp"):
                            outfile.write("%s\t%s\t%s\t%s" % (query, qLen, subject, sLen))
                            for tag in hspTags:
                                outfile.write("\t%s" % (hsp.findtext(tag)))
                            outfile.write('\n')
                    # prevents ElementTree from growing large datastructure
                    root.clear()
                    elem.clear()
        except Exception:
            sys.exit("The input data is malformed, or there is more than one dataset in the input file. Error: %s" % sys.exc_info()[1])


if __name__ == "__main__":
    __main__()