#!/usr/bin/env python3
import difflib
import filecmp
import os
import subprocess
import sys

from typing import Text

TOOLS_DIR = os.path.dirname(__file__)
ZULIP_PATH = os.path.dirname(TOOLS_DIR)
sys.path.append(ZULIP_PATH)
from scripts.lib.zulip_tools import run

PROD_LOCK_FILE = os.path.join(ZULIP_PATH, 'requirements', 'prod.txt')
DEV_LOCK_FILE = os.path.join(ZULIP_PATH, 'requirements', 'dev.txt')
TEST_PROD_LOCK_FILE = '/var/tmp/test_prod.txt'
TEST_DEV_LOCK_FILE = '/var/tmp/test_dev.txt'

def print_diff(path_file1, path_file2):
    # type: (Text, Text) -> None
    with open(path_file1) as file1:
        with open(path_file2) as file2:
            diff = difflib.unified_diff(
                file1.readlines(),
                file2.readlines(),
                fromfile=path_file1,
                tofile=path_file2,
            )
    for line in diff:
        print(line)

def main():
    # type: () -> None
    # `pip-compile` tries to avoid unnecessarily updating recursive dependencies
    # if lock files are present already. If we don't copy these files to the tmp
    # dir then recursive dependencies will get updated to their latest version
    # without any change in the input requirements file and the test will not pass.
    run(['cp', PROD_LOCK_FILE, TEST_PROD_LOCK_FILE])
    run(['cp', DEV_LOCK_FILE, TEST_DEV_LOCK_FILE])
    subprocess.check_call([os.path.join(TOOLS_DIR, 'update-locked-requirements'),
                           '--prod', TEST_PROD_LOCK_FILE, '--dev', TEST_DEV_LOCK_FILE,
                           ], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)

    same = filecmp.cmp(TEST_PROD_LOCK_FILE, PROD_LOCK_FILE, shallow=False)
    same = same or filecmp.cmp(TEST_DEV_LOCK_FILE, DEV_LOCK_FILE, shallow=False)

    if not same:
        print_diff(TEST_PROD_LOCK_FILE, PROD_LOCK_FILE)
        print_diff(TEST_DEV_LOCK_FILE, DEV_LOCK_FILE)
        # Flush the output to ensure we print the error at the end.
        sys.stdout.flush()
        raise Exception("Seems like you have updated some python dependencies but haven't "
                        "run updated requirements lock files. Please update them by running "
                        "`tools/update-locked-requirements`. For more information please refer "
                        "to `requirements/README.md`.")

if __name__ == '__main__':
    main()