// ❌ Standard cloud_firestore - Runtime errors waiting to happen
DocumentSnapshot doc = await FirebaseFirestore.instance
  .collection('users')
  .doc('user123')
  .get();

Map<String, dynamic>? data = doc.data() as Map<String, dynamic>?;
String name = data?['name']; // Runtime error if field doesn't exist
int age = data?['profile']['age']; // Nested access is fragile

// ✅ Firestore ODM - Compile-time safety
User? user = await db.users('user123').get();
String name = user.name; // IDE autocomplete, compile-time checking
int age = user.profile.age; // Type-safe nested access

// ❌ Standard - String-based field paths, typos cause runtime errors
final result = await FirebaseFirestore.instance
  .collection('users')
  .where('isActive', isEqualTo: true)
  .where('profile.followers', isGreaterThan: 100)
  .where('age', isLessThan: 30)
  .get();

// ✅ ODM - Type-safe query builder with IDE support
final result = await db.users
  .where(($) => $.and(
    $.isActive(isEqualTo: true),
    $.profile.followers(isGreaterThan: 100),
    $.age(isLessThan: 30),
  ))
  .get();

// ❌ Standard - Manual map construction, error-prone
await userDoc.update({
  'profile.followers': FieldValue.increment(1),
  'tags': FieldValue.arrayUnion(['verified']),
  'lastLogin': FieldValue.serverTimestamp(),
});

// ✅ ODM - Two powerful update strategies

// 1. Patch - Explicit atomic operations (Best Performance)
await userDoc.patch(($) => [
  $.profile.followers.increment(1),
  $.tags.add('verified'),              // Add single element
  $.tags.addAll(['premium', 'active']), // Add multiple elements
  $.scores.removeAll([0, -1]),         // Remove multiple elements
  $.lastLogin.serverTimestamp(),
]);

// 2. Modify - Smart atomic detection (Read + Auto-detect operations)
await userDoc.modify((user) => user.copyWith(
  age: user.age + 1,              // Auto-detects -> FieldValue.increment(1)
  tags: [...user.tags, 'expert'], // Auto-detects -> FieldValue.arrayUnion()
  lastLogin: FirestoreODM.serverTimestamp,
));

// Get first page with ordering
final page1 = await db.users
  .orderBy(($) => ($.followers(descending: true), $.name()))
  .limit(10)
  .get();

// Get next page with perfect type-safety - zero inconsistency risk
// The same orderBy ensures cursor consistency automatically
final page2 = await db.users
  .orderBy(($) => ($.followers(descending: true), $.name()))
  .startAfterObject(page1.last) // Auto-extracts cursor values
  .limit(10)
  .get();

// Live statistics that update in real-time
db.users
  .where(($) => $.isActive(isEqualTo: true))
  .aggregate(($) => (
    count: $.count(),
    averageAge: $.age.average(),
    totalFollowers: $.profile.followers.sum(),
  ))
  .stream
  .listen((stats) {
    print('Live: ${stats.count} users, avg age ${stats.averageAge}');
  });

await db.runTransaction((tx) async {
  // All reads happen first automatically
  final sender = await tx.users('user1').get();
  final receiver = await tx.users('user2').get();
  
  // Writes are automatically deferred until the end
  tx.users('user1').patch(($) => [$.balance.increment(-100)]);
  tx.users('user2').patch(($) => [$.balance.increment(100)]);
});

// Automatic management - simple and clean
await db.runBatch((batch) {
  batch.users.insert(newUser);
  batch.posts.update(existingPost);
  batch.users('user_id').posts.insert(userPost);
  batch.users('old_user').delete();
});

// Manual management - fine-grained control
final batch = db.batch();
batch.users.insert(user1);
batch.users.insert(user2);
batch.posts.update(post);
await batch.commit();

// lib/models/user.dart
import 'package:firestore_odm_annotation/firestore_odm_annotation.dart';
import 'package:freezed_annotation/freezed_annotation.dart';

part 'user.freezed.dart';
part 'user.g.dart';

@freezed
class User with _$User {
  const factory User({
    @DocumentIdField() required String id,
    required String name,
    required String email,
    required int age,
    DateTime? lastLogin,
  }) = _User;

  factory User.fromJson(Map<String, dynamic> json) => _$UserFromJson(json);
}

// lib/schema.dart
import 'package:firestore_odm_annotation/firestore_odm_annotation.dart';
import 'models/user.dart';

part 'schema.odm.dart';

@Schema()
@Collection<User>("users")
final appSchema = _$AppSchema;

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firestore_odm/firestore_odm.dart';
import 'schema.dart';

final firestore = FirebaseFirestore.instance;
final db = FirestoreODM(appSchema, firestore: firestore);

// Create a user with custom ID
await db.users.insert(User(
  id: 'jane',
  name: 'Jane Smith',
  email: 'jane@example.com',
  age: 28,
));

// Create a user with auto-generated ID
await db.users.insert(User(
  id: FirestoreODM.autoGeneratedId,
  name: 'John Doe',
  email: 'john@example.com',
  age: 30,
));

// Get a user
final user = await db.users('jane').get();
print(user?.name); // "Jane Smith"

// Type-safe queries
final youngUsers = await db.users
  .where(($) => $.age(isLessThan: 30))
  .orderBy(($) => $.name())
  .get();

@Schema()
@Collection<User>("users")
@Collection<Post>("posts")
@Collection<Post>("users/*/posts") // Same Post model, different location
final appSchema = _$AppSchema;

// Access user's posts
final userPosts = db.users('jane').posts;
await userPosts.insert(Post(id: 'post1', title: 'Hello World!'));

// Update all premium users using patch (best performance)
await db.users
  .where(($) => $.isPremium(isEqualTo: true))
  .patch(($) => [$.points.increment(100)]);

// Update all premium users using modify (read + auto-detect atomic)
await db.users
  .where(($) => $.isPremium(isEqualTo: true))
  .modify((user) => user.copyWith(points: user.points + 100));

// Delete inactive users
await db.users
  .where(($) => $.status(isEqualTo: 'inactive'))
  .delete();

// Server timestamps using patch (best performance)
await userDoc.patch(($) => [$.lastLogin.serverTimestamp()]);

// Server timestamps using modify (read + smart detection)
await userDoc.modify((user) => user.copyWith(
  loginCount: user.loginCount + 1,  // Uses current value + auto-detects increment
  lastLogin: FirestoreODM.serverTimestamp,
));

// ⚠️ IMPORTANT: Server timestamp arithmetic doesn't work
// ❌ This creates a regular DateTime, NOT a server timestamp:
// FirestoreODM.serverTimestamp + Duration(days: 1)

// Auto-generated document IDs
await db.users.insert(User(
  id: FirestoreODM.autoGeneratedId, // Server generates unique ID
  name: 'John Doe',
  email: 'john@example.com',
));

import 'package:fake_cloud_firestore/fake_cloud_firestore.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  test('user operations work correctly', () async {
    final firestore = FakeFirebaseFirestore();
    final db = FirestoreODM(appSchema, firestore: firestore);

    await db.users.insert(User(id: 'test', name: 'Test User', email: 'test@example.com', age: 25));

    final user = await db.users('test').get();
    expect(user?.name, 'Test User');
  });
}