#!/usr/bin/env python3
"""Post a prepared changelog after verifying a successful push to origin/main.

The webhook is local configuration, never a command-line argument or tracked file.
API: https://docs.discord.com/developers/resources/webhook#execute-webhook
"""
import argparse
import json
import shlex
import subprocess
import sys
import urllib.error
import urllib.parse
import urllib.request
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]


class NoRedirect(urllib.request.HTTPRedirectHandler):
    def redirect_request(self, req, fp, code, msg, headers, newurl):
        return None


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--commit', required=True, help='Commit just pushed to origin/main')
    parser.add_argument('--message-file', required=True, type=Path, help='Prepared player-facing changelog, at most 2000 characters')
    args = parser.parse_args()
    commit = subprocess.check_output(['git', 'rev-parse', '--verify', args.commit + '^{commit}'], cwd=ROOT, text=True).strip()
    ssh = 'ssh -F ' + shlex.quote(str(Path.home() / '.ssh/config'))
    remote = subprocess.check_output(['git', '-c', 'core.sshCommand=' + ssh, 'ls-remote', '--exit-code', 'origin', 'refs/heads/main'], cwd=ROOT, text=True).split()[0]
    if commit != remote:
        parser.error('Requested commit is not the current origin/main tip; no message sent.')
    message = args.message_file.read_text().strip()
    if not message or len(message) > 2000:
        parser.error('Changelog must contain 1..2000 characters.')
    state_path = ROOT / '.local/discord-changelog-state.json'
    state = json.loads(state_path.read_text()) if state_path.exists() else {}
    if state.get('commit') == commit:
        print('This commit is already recorded; no duplicate sent. Status: ' + state.get('status', 'unknown'))
        return
    url = (ROOT / '.local/discord-webhook.url').read_text().strip()
    parsed = urllib.parse.urlsplit(url)
    if parsed.scheme != 'https' or parsed.netloc != 'discord.com' or not parsed.path.startswith('/api/webhooks/') or parsed.query or parsed.fragment:
        parser.error('Local configuration must contain a Discord HTTPS webhook URL.')
    payload = json.dumps({'content': message, 'allowed_mentions': {'parse': []}}).encode()
    request = urllib.request.Request(url + '?wait=true', data=payload, headers={
        'Content-Type': 'application/json', 'User-Agent': 'EscapistsReintroduced-Changelog/1.0'})
    # Preserve an uncertain attempt so a timeout cannot silently cause duplicates.
    state_path.write_text(json.dumps({'commit': commit, 'status': 'pending'}) + '\n')
    try:
        with urllib.request.build_opener(NoRedirect()).open(request, timeout=30) as response:
            result = json.load(response)
        if not result.get('id'):
            raise ValueError('Missing message confirmation')
    except urllib.error.HTTPError as error:
        print('Discord returned HTTP ' + str(error.code) + '; inspect delivery before retrying.', file=sys.stderr)
        return 1
    except (urllib.error.URLError, TimeoutError, ValueError):
        print('Discord delivery could not be confirmed; inspect delivery before retrying.', file=sys.stderr)
        return 1
    state_path.write_text(json.dumps({'commit': commit, 'status': 'sent', 'message_id': result['id']}) + '\n')
    print('Discord changelog delivered for ' + commit[:7])
    return 0


if __name__ == '__main__':
    sys.exit(main())