from .. import functional as f
import argparse
import uuid
import json
import os
import sys
import traceback


def main(argv=sys.argv):
    import argparse

    description = """
Given the result of 'DBstats -u -b1' on stdin,
print the lowest read-length required for sufficient coverage of the genome
(i.e. 'length_cutoff').
"""
    epilog = """
This is useful when length_cutoff is not provided but the genome-size
can be estimated. The purpose is to *reduce* the amount of data seen by
DALIGNER, since otherwise it will miss many alignments when it
encounters resource limits.

Note: If PBFALCON_ERRFILE is defined (and its directory is writable),
we will write errors there in addition to stderr.
"""
    parser = argparse.ArgumentParser(description=description, epilog=epilog,
                                     formatter_class=argparse.ArgumentDefaultsHelpFormatter)
    parser.add_argument('--coverage', type=float, default=20,
                        help='Desired coverage ratio (i.e. over-sampling)')
    parser.add_argument('genome_size', type=int,
                        help='Estimated number of bases in genome. (haploid?)')
    parser.add_argument('capture',  # default='-', # I guess default is not allowed for required args.
                        help='File with captured output of DBstats. (Otherwise, stdin.)')
    args = parser.parse_args(argv[1:])

    target = int(args.genome_size * args.coverage)
    def capture():
        # This generator ensures that our file is closed at end-of-program.
        if args.capture != '-':
            with open(args.capture) as sin:
                yield sin
        else:
            yield sys.stdin
    for sin in capture():
        stats = sin.read()
    try:
        cutoff = f.calc_cutoff(target, stats)
    except Exception as e:
        tb = traceback.format_exc()
        msg = 'User-provided genome_size: {}\nDesired coverage: {}\n'.format(
            args.genome_size, args.coverage)
        # pbfalcon wants us to write errs here.
        errfile = os.environ.get('PBFALCON_ERRFILE')
        if errfile:
            with open(errfile, 'w') as ofs:
                ofs.write(tb + msg)
        # this is propagated to SMRT Link UI
        # see PacBioAlarm class in pbcommand.models.common for details
        with open("alarms.json", "w") as alarms_out:
            alarms_out.write(json.dumps([
                {
                    "exception": e.__class__.__name__,
                    "info": tb,
                    "message": str(e) + "\n" + msg,
                    "name": e.__class__.__name__,
                    "severity": "ERROR",
                    "owner": "python3",
                    "id": str(uuid.uuid4())
                }]))
        raise Exception(tb + msg)
    sys.stdout.write(str(cutoff))


if __name__ == "__main__":
    main(sys.argv)