import 'dart:convert';
import 'dart:io';

import 'package:shelf/shelf.dart';

import '../db.dart';
import '../firebase_auth.dart';

Handler profileHandler({
  required ProfileDb db,
  required FirebaseAuthVerifier auth,
}) {
  return (Request request) async {
    if (request.method == 'OPTIONS') {
      return Response.ok('', headers: _corsHeaders);
    }

    final String? firebaseUid = await auth.verifyBearerToken(
      request.headers['Authorization'] ?? request.headers['authorization'],
    );
    if (firebaseUid == null) {
      return _jsonResponse(401, <String, dynamic>{'error': 'Unauthorized'});
    }

    if (request.requestedUri.path != '/v1/me/profile') {
      return _jsonResponse(404, <String, dynamic>{'error': 'Not found'});
    }

    try {
      if (request.method == 'GET') {
        final Map<String, dynamic>? profile = await db.getProfile(firebaseUid);
        if (profile == null) {
          return _jsonResponse(404, <String, dynamic>{'error': 'Not found'});
        }
        return _jsonResponse(200, profile);
      }

      if (request.method == 'PUT') {
        final String body = await request.readAsString();
        final Map<String, dynamic> json =
            jsonDecode(body) as Map<String, dynamic>;
        final int revision = (json['revision'] as num?)?.toInt() ?? 1;

        try {
          final Map<String, dynamic> saved = await db.upsertProfile(
            firebaseUid: firebaseUid,
            body: json,
            clientRevision: revision,
          );
          return _jsonResponse(200, saved);
        } on StaleRevisionException catch (e) {
          return _jsonResponse(409, <String, dynamic>{
            'error': 'Conflict',
            'profile': e.serverProfile,
          });
        }
      }

      return _jsonResponse(405, <String, dynamic>{'error': 'Method not allowed'});
    } catch (e, st) {
      stderr.writeln('Profile handler error: $e\n$st');
      return _jsonResponse(500, <String, dynamic>{'error': 'Internal error'});
    }
  };
}

Map<String, String> get _corsHeaders => <String, String>{
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Methods': 'GET, PUT, OPTIONS',
  'Access-Control-Allow-Headers': 'Authorization, Content-Type',
};

Response _jsonResponse(int status, Map<String, dynamic> body) {
  return Response(
    status,
    body: jsonEncode(body),
    headers: <String, String>{
      ..._corsHeaders,
      'Content-Type': 'application/json',
    },
  );
}