# Description: Script to migrate repositories from GitLab to Gitea
# Author: Enrico Ludwig <enrico.ludwig@zion-networks.de>
# Version: 1.0
# Date: 2021-01-06
#
# Precedence of settings: arguments > .env file > environment variables > default values
#
# Usage:
# python3 gitlab2gitea.py [options]
#
#   --gitlab-token <GITLAB_TOKEN>               GitLab access token
#   --gitlab-url <GITLAB_URL>                   GitLab URL
#   --gitlab-api-version <GITLAB_API_VERSION>   GitLab API version (default: v4)
#   --gitea-token <GITEA_TOKEN>                 Gitea access token
#   --gitea-url <GITEA_URL>                     Gitea URL
#   --gitea-api-version <GITEA_API_VERSION>     Gitea API version (default: v1)
#
#   --create-missing-groups                     Create missing groups on Gitea (default: False)
#   --create-missing-users                      Create missing users on Gitea (default: False)
#
#   --quiet                                     Enable quiet mode (default: False)
#   --debug                                     Enable debug mode (default: False)
#   --trace                                     Enable trace mode (default: False)
#   --dry-run                                   Enable dry-run mode (default: False)
#   --log-file <LOG_FILE>                       Log file (default: gitlab2gitea.log)
#                                               If not set, logs will be only printed to stdout
#   --append-log                                Append log file (default: False)
#
# Example:
#  python3 gitlab2gitea.py \
#    --gitlab-url <GITLAB_URL> \
#    --gitlab-token <GITLAB_TOKEN> \
#    --gitea-url <GITEA_URL> \
#    --gitea-token <GITEA_TOKEN>

# Settings - GitLab

GITLAB_URL = ''
GITLAB_TOKEN = ''
GITLAB_API_VERSION = 'v4'

# Settings - Gitea

GITEA_URL = ''
GITEA_TOKEN = ''
GITEA_API_VERSION = 'v1'

# Settings - General Repository

CREATE_MISSING_GROUPS = False
CREATE_MISSING_USERS = False

# Settings - General

DEBUG = False
TRACE = False
DRY_RUN = False
LOG_FILE = 'gitlab2gitea.log'
APPEND_LOG = False
QUIET = False

# Imports

import os
import sys
import argparse
import requests

# Set cwd to script directory

os.chdir(os.path.dirname(os.path.realpath(__file__)))

# Read environment variables
if 'GITLAB_URL' in os.environ:
    GITLAB_URL = os.environ['GITLAB_URL']

if 'GITLAB_TOKEN' in os.environ:
    GITLAB_TOKEN = os.environ['GITLAB_TOKEN']

if 'GITLAB_API_VERSION' in os.environ:
    GITLAB_API_VERSION = os.environ['GITLAB_API_VERSION']

if 'GITEA_URL' in os.environ:
    GITEA_URL = os.environ['GITEA_URL']

if 'GITEA_TOKEN' in os.environ:
    GITEA_TOKEN = os.environ['GITEA_TOKEN']

if 'GITEA_API_VERSION' in os.environ:
    GITEA_API_VERSION = os.environ['GITEA_API_VERSION']

if 'CREATE_MISSING_GROUPS' in os.environ:
    CREATE_MISSING_GROUPS = bool(os.environ['CREATE_MISSING_GROUPS'])

if 'CREATE_MISSING_USERS' in os.environ:
    CREATE_MISSING_USERS = bool(os.environ['CREATE_MISSING_USERS'])

if 'QUIET' in os.environ:
    QUIET = bool(os.environ['QUIET'])

if 'DEBUG' in os.environ:
    DEBUG = bool(os.environ['DEBUG'])

if 'TRACE' in os.environ:
    TRACE = bool(os.environ['TRACE'])

if 'DRY_RUN' in os.environ:
    DRY_RUN = bool(os.environ['DRY_RUN'])

if 'LOG_FILE' in os.environ:
    LOG_FILE = os.environ['LOG_FILE']

if 'APPEND_LOG' in os.environ:
    APPEND_LOG = bool(os.environ['APPEND_LOG'])

# Read .env file if exists and override environment variables

if os.path.exists('.env'):
    with open('.env', 'r') as env_file:
        for line in env_file:
            # skip comments, empty lines and lines without '='
            if line.startswith('#') or not '=' in line:
                continue

            key, value = line.strip().split('=')

            if key == 'GITLAB_API_VERSION':
                GITLAB_API_VERSION = value

            if key == 'GITLAB_URL':
                GITLAB_URL = value

            if key == 'GITLAB_TOKEN':
                GITLAB_TOKEN = value

            if key == 'GITEA_URL':
                GITEA_URL = value

            if key == 'GITEA_TOKEN':
                GITEA_TOKEN = value
            
            if key == 'GITEA_API_VERSION':
                GITEA_API_VERSION = value
            
            if key == 'CREATE_MISSING_GROUPS':
                if value.lower() == 'true' or value == '1':
                    CREATE_MISSING_GROUPS = True
            
            if key == 'CREATE_MISSING_USERS':
                if value.lower() == 'true' or value == '1':
                    CREATE_MISSING_USERS = True

            if key == 'QUIET':
                QUIET = bool(value)

            if key == 'DEBUG':
                if value.lower() == 'true' or value == '1':
                    DEBUG = True
            
            if key == 'TRACE':
                if value.lower() == 'true' or value == '1':
                    TRACE = True

            if key == 'DRY_RUN':
                if value.lower() == 'true' or value == '1':
                    DRY_RUN = True

            if key == 'LOG_FILE':
                LOG_FILE = value
            
            if key == 'APPEND_LOG':
                APPEND_LOG = bool(value)

# Read arguments and override environment variables

parser = argparse.ArgumentParser(description='Script to migrate repositories from GitLab to Gitea')

parser.add_argument('--gitlab-api-version', help='GitLab API version', default='v4')
parser.add_argument('--gitlab-token', help='GitLab access token')
parser.add_argument('--gitea-token', help='Gitea access token')
parser.add_argument('--gitlab-url', help='GitLab URL')
parser.add_argument('--gitea-url', help='Gitea URL')
parser.add_argument('--gitea-api-version', help='Gitea API version', default='v1')
parser.add_argument('--create-missing-groups', help='Create missing groups on Gitea', action='store_true')
parser.add_argument('--create-missing-users', help='Create missing users on Gitea', action='store_true')
parser.add_argument('--quiet', help='Enable quiet mode', action='store_true')
parser.add_argument('--debug', help='Enable debug mode', action='store_true')
parser.add_argument('--trace', help='Enable trace mode', action='store_true')
parser.add_argument('--dry-run', help='Enable dry-run mode', action='store_true')
parser.add_argument('--log-file', help='Log file', default='gitlab2gitea.log')
parser.add_argument('--append-log', help='Append log file', action='store_true')

args = parser.parse_args()

if args.gitlab_api_version:
    GITLAB_API_VERSION = args.gitlab_api_version

if args.gitlab_token:
    GITLAB_TOKEN = args.gitlab_token

if args.gitlab_url:
    GITLAB_URL = args.gitlab_url

if args.gitea_token:
    GITEA_TOKEN = args.gitea_token

if args.gitea_url:
    GITEA_URL = args.gitea_url

if args.gitea_api_version:
    GITEA_API_VERSION = args.gitea_api_version

if args.create_missing_groups:
    CREATE_MISSING_GROUPS = True

if args.create_missing_users:
    CREATE_MISSING_USERS = True

if args.quiet:
    QUIET = True

if args.debug:
    DEBUG = True

if args.trace:
    TRACE = True

if args.dry_run:
    DRY_RUN = True

if args.log_file:
    LOG_FILE = args.log_file

if args.append_log:
    APPEND_LOG = True

# Remove trailing slashes from URLs

GITLAB_URL = GITLAB_URL.rstrip('/')
GITEA_URL = GITEA_URL.rstrip('/')

# Internal functions

def _trace(message):
    if TRACE:
        print('\033[1m\033[36m[TRC]\033[0m', message)

        if LOG_FILE:
            with open(LOG_FILE, 'a') as log_file:
                log_file.write(f'[TRC] {message}\n')

def _debug(message):
    if TRACE or DEBUG:
        print('\033[1m\033[34m[DBG]\033[0m', message)

        if LOG_FILE:
            with open(LOG_FILE, 'a') as log_file:
                log_file.write(f'[DBG] {message}\n')

def _info(message):
    print('\033[1m\033[32m[INF]\033[0m', message)

    if LOG_FILE:
        with open(LOG_FILE, 'a') as log_file:
            log_file.write(f'[INF] {message}\n')

def _warn(message):
    print('\033[1m\033[33m[WRN]\033[0m', message)

    if LOG_FILE:
        with open(LOG_FILE, 'a') as log_file:
            log_file.write(f'[WRN] {message}\n')

def _error(message):
    print('\033[1m\033[31m[ERR]\033[0m', message)

    if LOG_FILE:
        with open(LOG_FILE, 'a') as log_file:
            log_file.write(f'[ERR] {message}\n')

# PROGRAM

# Endpoint: GET /api/{GITLAB_API_VERSION}/version
def check_gitlab():
    _debug(f'REQUEST: {GITLAB_URL}/api/{GITLAB_API_VERSION}/version')

    response = requests.get(f'{GITLAB_URL}/api/{GITLAB_API_VERSION}/version', headers={
        'Content-Type': 'application/json',
        'Accept': 'application/json',
        'Authorization': f'Bearer {GITLAB_TOKEN}'
    })

    _trace(f'RESPONSE: {response.json()}')

    if response.status_code != 200:
        response_message = response.json()['message'] if 'message' in response.json() else 'Unknown error'
        raise Exception(f'GitLab endpoint test failed: {response_message}')
    else:
        _info(f'GitLab endpoint version: {response.json()["version"]}')

# Endpoint: GET /api/{GITEA_API_VERSION}/version
def check_gitea():
    _debug(f'REQUEST: {GITEA_URL}/api/{GITEA_API_VERSION}/version')

    response = requests.get(f'{GITEA_URL}/api/{GITEA_API_VERSION}/version', headers={
        'Content-Type': 'application/json',
        'Accept': 'application/json',
        'Authorization': f'token {GITEA_TOKEN}'
    })

    _trace(f'RESPONSE: {response.json()}')
    
    if response.status_code != 200:
        response_message = response.json()['message'] if 'message' in response.json() else 'Unknown error'
        raise Exception(f'Gitea endpoint test failed: {response_message}')
    else:
        _info(f'Gitea endpoint version: {response.json()["version"]}')

# Endpoint: GET /api/{GITLAB_API_VERSION}/groups
def get_gitlab_groups() -> list:
    groups = []

    _debug(f'REQUEST: {GITLAB_URL}/api/{GITLAB_API_VERSION}/groups')

    response = requests.get(f'{GITLAB_URL}/api/{GITLAB_API_VERSION}/groups',                    
        params={
            'all_available': 1,
            'per_page': 100,
            'page': 1,
            'top_level_only': 1
        },
        headers={
        'Content-Type': 'application/json',
        'Accept': 'application/json',
        'Authorization': f'Bearer {GITLAB_TOKEN}'
    })

    if response.status_code != 200:
        response_message = response.json()['message'] if 'message' in response.json() else 'Unknown error'
        raise Exception(f'Failed to get GitLab groups: {response_message}')
    else:
        groups = response.json()

    return groups

# Endpoint: GET /api/{GITLAB_API_VERSION}/users
def get_gitlab_users() -> list:
    pass

# Endpoint: GET /api/{GITLAB_API_VERSION}/projects
def get_gitlab_projects() -> list:
    pass

# Endpoint: GET /api/{GITEA_API_VERSION}/orgs
def get_gitea_groups() -> list:
    groups = []

    _debug(f'REQUEST: {GITEA_URL}/api/{GITEA_API_VERSION}/orgs?all_available=1&per_page=100')

    response = requests.get(f'{GITEA_URL}/api/{GITEA_API_VERSION}/orgs',
        headers={
            'Content-Type': 'application/json',
            'Accept': 'application/json',
            'Authorization': f'token {GITEA_TOKEN}'
        })

    if response.status_code != 200:
        response_message = response.json()['message'] if 'message' in response.json() else 'Unknown error'
        raise Exception(f'Failed to get Gitea groups: {response_message}')
    else:
        groups = response.json()

    return groups

# Endpoint: GET /api/{GITEA_API_VERSION}/users
def get_gitea_users() -> list:
    pass

# Endpoint: GET /api/{GITEA_API_VERSION}/repos
def get_gitea_projects() -> list:
    pass

def cmp_gitlab_gitea_groups(gitlab_groups: list, gitea_groups: list) -> dict:

    # 0 = exists on both
    # 1 = exists on GitLab only
    # 2 = exists on Gitea only
    # planned structure:
    # {
    #   'groupname' : 0,
    #   'groupname2' : 1,
    #   'groupname3' : 2
    # }

    # Example for GitLab groups
    # [
    #     {
    #         "id": 15,
    #         "web_url": "https://git.madaboutpandas.com/groups/administration",
    #         "name": "Administration",
    #         "path": "administration",
    #         "description": "",
    #         "visibility": "private",
    #         "share_with_group_lock": false,
    #         "require_two_factor_authentication": false,
    #         "two_factor_grace_period": 48,
    #         "project_creation_level": "developer",
    #         "auto_devops_enabled": null,
    #         "subgroup_creation_level": "maintainer",
    #         "emails_disabled": false,
    #         "emails_enabled": true,
    #         "mentions_disabled": null,
    #         "lfs_enabled": true,
    #         "math_rendering_limits_enabled": true,
    #         "lock_math_rendering_limits_enabled": false,
    #         "default_branch": null,
    #         "default_branch_protection": 1,
    #         "default_branch_protection_defaults": {
    #             "allowed_to_push": [{"access_level": 30}],
    #             "allow_force_push": false,
    #             "allowed_to_merge": [{"access_level": 40}]
    #         },
    #         "avatar_url": null,
    #         "request_access_enabled": true,
    #         "full_name": "Administration",
    #         "full_path": "administration",
    #         "created_at": "2020-08-10T20:27:23.487Z",
    #         "parent_id": null,
    #         "organization_id": 1,
    #         "shared_runners_setting": "enabled",
    #         "ldap_cn": null,
    #         "ldap_access": null,
    #         "wiki_access_level": "enabled"
    #     }
    # ]

    # Example for Gitea groups
    # [
    #     {
    #         "id": 3,
    #         "name": "YerbaBuena",
    #         "full_name": "",
    #         "email": "",
    #         "avatar_url": "http://10.17.1.21/avatars/9f8ea65601abbf666adcec2b128180e4",
    #         "description": "",
    #         "website": "",
    #         "location": "",
    #         "visibility": "public",
    #         "repo_admin_change_team_access": True,
    #         "username": "YerbaBuena",
    #     }
    # ]

    compare_result = {}
    missing_matches = 0

    for gitlab_group in gitlab_groups:
        name = gitlab_group['path']
        exists = False

        for gitea_group in gitea_groups:
            if name == gitea_group['name']:
                exists = True
                break

        if exists:
            _info(f'GITLAB: Group "{name}" exists on both GitLab and Gitea')
        else:
            _warn(f'GITLAB: Group "{name}" exists on GitLab only')
            missing_matches += 1
        
        compare_result[name] = 0 if exists else 1
    
    for gitea_group in gitea_groups:
        name = gitea_group['name']
        exists = False

        for gitlab_group in gitlab_groups:
            if name == gitlab_group['path']:
                exists = True
                break

        if not exists:
            _warn(f'GITEA: Group "{name}" exists on Gitea only')
            compare_result[name] = 2
    
    return compare_result, missing_matches

def cmp_gitlab_gitea_users(gitlab_users: list, gitea_users: list) -> dict:
    pass

def cmp_gitlab_gitea_projects(gitlab_projects: list, gitea_projects: list) -> dict:
    pass

def create_missing_groups(gitlab_groups: list, gitea_groups: list):
    pass

def run_migration():
    
    _info('Migrating GitLab groups...')

    gitlab_groups = get_gitlab_groups()
    gitea_groups = get_gitea_groups()

    _debug(f'Groups on GitLab: {len(gitlab_groups)}')
    _trace(f'Groups on GitLab: {gitlab_groups}')
    _debug(f'Groups on Gitea: {len(gitea_groups)}')
    _trace(f'Groups on Gitea: {gitea_groups}')

    group_result, missing_matches = cmp_gitlab_gitea_groups(gitlab_groups, gitea_groups)

    if missing_matches > 0:
        _warn(f'{missing_matches} groups are missing on Gitea!')
    
    if missing_matches > 0 and CREATE_MISSING_GROUPS:
        _info('Creating missing groups on Gitea...')

        create_missing_groups(gitlab_groups, gitea_groups)

    _info('Migrating GitLab users...')

    gitlab_users = get_gitlab_users()
    gitea_users = get_gitea_users()

    cmp_gitlab_gitea_users(gitlab_users, gitea_users)

    _info('Migrating GitLab projects...')

    gitlab_projects = get_gitlab_projects()
    gitea_projects = get_gitea_projects()

    cmp_gitlab_gitea_projects(gitlab_projects, gitea_projects)

def main():
    _info('Gitlab2Gitea v1.0 - by Zion Networks')
    _info('------------------------------------')
    _info('')

    if sys.version_info < (3, 6):
        _error('Python 3.6 or higher is required!')
        return
    else:
        _debug(f'Python version: {sys.version_info.major}.{sys.version_info.minor}')

    if not GITLAB_TOKEN:
        _error('GitLab access token is missing!')
        return

    if not GITEA_TOKEN:
        _error('Gitea access token is missing!')
        return
    
    if LOG_FILE and not APPEND_LOG:
        with open(LOG_FILE, 'w') as log_file:
            log_file.write('')
    
    _debug(f'GitLab URL: {GITLAB_URL}')
    _debug(f'Gitea URL: {GITEA_URL}')
    _debug(f'Logging to: {LOG_FILE}')

    if DRY_RUN:
        _warn('Running in dry-run mode!')

    _info('Testing endpoints...')

    try:
        check_gitlab()
        check_gitea()
    except Exception as e:
        _error(f'An error occurred: {e}')
        return
    
    _info('Starting migration...')

    try:
        run_migration()
    except Exception as e:
        _error(f'An error occurred: {e}')

if __name__ == '__main__':
    main()