"""Pulls changelists from Perforce into a Bazaar shared repository.

For example,

    > pull.py //depot/project C:\\repo

Requires that the P4PORT and P4USER environment variables are set.

Requires that bzrp4 is installed as a Bazaar plugin.
"""

import os
import os.path
import P4
import subprocess
import sys


def p4_fast_export_path():
    dir = os.path.dirname(__file__)
    return os.path.join(dir, 'p4-fast-export.py')


def last_change_in_source_depot_path(src):
    p4 = P4.P4()
    p4.connect()
    result = p4.run_changes('-m', '1', p4_wildcard(src))
    p4.disconnect()
    return result[0]['change']


def parse_change_from_marks_line(line):
    return int(line[1:line.find(' ')])


def last_change_in_marks_file(dest):
    last_change = 0
    try:
        marks_file = open(marks_file_path(dest), 'r')
        for line in marks_file:
            if ':' == line[0]:
                change = parse_change_from_marks_line(line)
                if change > last_change:
                    last_change = change
    except IOError:
        pass
    return last_change


def range_begin(dest):
    last_change = last_change_in_marks_file(dest)
    return str(last_change + 1)


def range_end(src):
    return last_change_in_source_depot_path(src)


def p4_wildcard(path):
    return '%s/...' % path


def manual_range(src):
    return -1 != src.find('@')


def computed_range(src):
    return not manual_range(src)


def depot_path_and_range(src, dest):
    if manual_range(src):
        return src
    else:
        return '%s@%s,%s' % (src, range_begin(dest), range_end(src))


def marks_file_path(dest):
    return os.path.join(dest, '.bzr', 'repository', 'fastimport-id-map')


def export_file_path(dest):
    return os.path.join(dest, '.bzr', 'repository', 'p4-fastexport')


def bzr_fast_import_command(dest):
    # TODO: Make this portable, not Windows-specific.
    command = ['bzr.bat', 'fast-import', '-']
    return command


def pull(src, dest):
    print depot_path_and_range(src, dest)
    if computed_range(src) and range_begin(dest) > range_end(src):
        return
    export_file = open(export_file_path(dest), 'ab')
    try:
        export_file.seek(0, os.SEEK_END)
        proc1 = subprocess.Popen(['python', p4_fast_export_path(),
                                  depot_path_and_range(src, dest)],
                                 stdout=export_file)
        if 0 != proc1.wait():
            raise IOError()
    except Exception, e:
        raise e
    finally:
        export_file.close()
    import_file = open(export_file_path(dest), 'rb')
    try:
        proc2 = subprocess.Popen(bzr_fast_import_command(dest),
                                 stdin=import_file,
                                 cwd=dest)
        if 0 != proc2.wait():
            raise IOError()
    except Exception, e:
        raise e
    finally:
        import_file.close()


def main(args):
    pull_src = args[0]
    pull_dest = args[1]
    pull(pull_src, pull_dest)
    

if __name__ == '__main__':
    main(sys.argv[1:])