#!/usr/bin/env python3
import fileinput
import glob
import os
import re
import sys
from typing import List


def validate_order(order: List[int], length: int) -> None:
    if len(order) != length:
        print("Please enter the sequence of all the conflicting files at once")
        sys.exit(1)

    for i in order:
        if i > length or i < 1 or order.count(i) > 1:
            print("Incorrect input")
            sys.exit(1)

def renumber_migration(conflicts: List[str], order: List[int], last_correct_migration: str) -> None:
    stack: List[str] = []
    for i in order:
        if conflicts[i-1][0:4] not in stack:
            stack.append(conflicts[i-1][0:4])
        else:
            # Replace dependencies with the last correct migration
            file = fileinput.FileInput('zerver/migrations/' + conflicts[i-1], inplace=True)
            for line in file:
                print(re.sub(r'[\d]+(_[a-z0-9]+)+', last_correct_migration, line), end='')

            # Rename the migration indexing at the end
            new_name = conflicts[i-1].replace(conflicts[i-1][0:4],
                                              f'{int(last_correct_migration[0:4]) + 1:04}')
            os.rename('zerver/migrations/' + conflicts[i-1], 'zerver/migrations/' + new_name)

            last_correct_migration = new_name.replace('.py', '')

def resolve_conflicts(conflicts: List[str], files_list: List[str]) -> None:
    print("Conflicting migrations:")
    for i in range(0, len(conflicts)):
        print(str(i+1) + '. ' + conflicts[i])

    order_input = input("Enter the order in which these migrations should be arranged: ")
    order = list(map(int, order_input.split()))
    validate_order(order, len(conflicts))

    last_correct_migration = conflicts[order[0] - 1]

    last_correct_migration = last_correct_migration.replace('.py', '')
    renumber_migration(conflicts, order, last_correct_migration)

if __name__ == '__main__':

    MIGRATIONS_TO_SKIP = {'0209', '0261'}
    while True:
        conflicts: List[str] = []
        stack: List[str] = []
        files_list = [os.path.basename(path) for path in glob.glob("zerver/migrations/????_*.py")]
        file_index = [file[0:4] for file in files_list]

        for file in file_index:
            migration_number = file[0:4]
            counter = file_index.count(migration_number)

            if counter > 1 and file[0:4] not in stack:
                # When we need to backport migrations to a previous
                # release, we sometimes end up with multiple having
                # the same ID number (which isn't a problem; the
                # migrations graph structure, not the IDs, is what
                # matters).
                if migration_number not in MIGRATIONS_TO_SKIP:
                    conflicts += [file_name for file_name in files_list if file_name.startswith(migration_number)]
                    stack.append(migration_number)

        if len(conflicts) > 0:
            resolve_conflicts(conflicts, files_list)
        else:
            break

    print("All conflicts resolved")