#!/usr/bin/env python3
#
# This is really similar to "p4 reconcile", except that it
# reconciles from an external directory, "source_dir", to
# the Perforce repo, "perforce_dir".
#
# Eg., to preview the changes that would be made:
#
# ./same_as_p4_reconcile.py -n -c 42 source_dir perforce_dir
#
# To perform the actual reconciliation, drop the "-n":
#
# ./same_as_p4_reconcile.py -c 42 source_dir perforce_dir

import os
from argparse import ArgumentParser
import subprocess
import shutil
import filecmp
from typing import Optional, List


def call(cmd_array: List[str], changelist: str, preview: bool) -> int:
    """ If not preview, makes the call."""
    ret = 0
    if not preview:
        ret = subprocess.call(add_changelist_to_cmd(cmd_array, changelist))
        if ret != 0:
            print("ERROR: Couldn't %s, ret = %d" % (str(cmd_array), ret))
    else:
        print('#', ' '.join(cmd_array))
    return ret


def add_changelist_to_cmd(cmd: List[str], changelist: Optional[str]) -> List[str]:
    """Injects "-c changelist" to the p4 command."""
    if changelist is None:
        return cmd
    cmd.insert(2, '-c')
    cmd.insert(3, changelist)
    return cmd


def do_diff_by_name(preview: bool, changelist: str, source_dir: str, p4_dir: str) -> None:
    do_diff(preview, changelist, filecmp.dircmp(p4_dir, source_dir))
    delete_empty_directories(p4_dir)


def delete_empty_directories(top: str) -> None:
    """ p4 deletes could leave us with empty hierarchies. """
    for root, dirs, files in os.walk(top, topdown=False):
        for name in dirs:
            try:
                os.rmdir(os.path.join(root,name))
            except OSError as ex:
                pass


def do_diff(preview: bool, changelist:str, d: filecmp.dircmp) -> None:
    for f in d.right_only:
        if os.path.isfile(os.path.join(d.right, f)):
            if not preview:
                shutil.copy(os.path.join(d.right, f), os.path.join(d.left, f))
            call(['p4', 'add', os.path.join(d.left, f)], changelist, preview)
        else:
            # Can't add directory in one step. Do so by walking dir.
            if not preview:
                shutil.copytree(os.path.join(d.right, f), os.path.join(d.left, f))
                for root, dirs, files in os.walk(os.path.join(d.left, f)):
                    for f in files:
                        call(['p4', 'add', os.path.join(root, f)], changelist, preview)
            else:
                print('# Adding hierarchy', os.path.join(d.right, f))

    for f in d.left_only:
        if os.path.isfile(os.path.join(d.left, f)):
            call(['p4', 'delete', os.path.join(d.left, f)], changelist, preview)
        else:
            for root, dirs, files in os.walk(os.path.join(d.left, f)):
                for f in files:
                    call(['p4', 'delete', os.path.join(root, f)], changelist, preview)

    for f in d.diff_files:
        if not call(['p4', 'edit', os.path.join(d.left, f)], changelist, preview):
            # call() returning 0 is a successful call
            if not preview:
                shutil.copy(os.path.join(d.right, f), os.path.join(d.left, f))

    for sub in d.subdirs.values():
        do_diff(preview, changelist, sub)


if __name__ == '__main__':
    parser = ArgumentParser(description='Similar to "p4 reconcile"')
    parser.add_argument('-c', '--changelist', help='Changelist to use')
    parser.add_argument('-n', '--preview', action='store_true', help="Preview only, don't change any files")
    parser.add_argument('source_dir', help='The newer directory outside perforce')
    parser.add_argument('p4_dir', help='The perforce directory to be modified')
    args = parser.parse_args()
    do_diff_by_name(args.preview, args.changelist, args.source_dir, args.p4_dir)