import 'dart:io';

import 'package:drift/drift.dart';
import 'package:drift/native.dart';
import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';
import 'package:trainhub_flutter/core/constants/app_constants.dart';
import 'package:trainhub_flutter/data/database/daos/analysis_dao.dart';
import 'package:trainhub_flutter/data/database/daos/chat_dao.dart';
import 'package:trainhub_flutter/data/database/daos/exercise_dao.dart';
import 'package:trainhub_flutter/data/database/daos/knowledge_chunk_dao.dart';
import 'package:trainhub_flutter/data/database/daos/program_dao.dart';
import 'package:trainhub_flutter/data/database/daos/training_plan_dao.dart';

part 'app_database.g.dart';

// ---------------------------------------------------------------------------
// Existing tables (unchanged)
// ---------------------------------------------------------------------------

class Exercises extends Table {
  TextColumn get id => text()();
  TextColumn get name => text()();
  TextColumn get instructions => text().nullable()();
  TextColumn get enrichment => text().nullable()();
  TextColumn get tags => text().nullable()();
  TextColumn get videoUrl => text().nullable()();

  @override
  Set<Column> get primaryKey => {id};
}

class TrainingPlans extends Table {
  TextColumn get id => text()();
  TextColumn get name => text()();
  TextColumn get sections => text().nullable()();

  @override
  Set<Column> get primaryKey => {id};
}

class Programs extends Table {
  TextColumn get id => text()();
  TextColumn get name => text()();
  TextColumn get createdAt => text()();

  @override
  Set<Column> get primaryKey => {id};
}

class ProgramWeeks extends Table {
  TextColumn get id => text()();
  TextColumn get programId =>
      text().references(Programs, #id, onDelete: KeyAction.cascade)();
  IntColumn get position => integer()();
  TextColumn get notes => text().nullable()();

  @override
  Set<Column> get primaryKey => {id};
}

class ProgramWorkouts extends Table {
  TextColumn get id => text()();
  TextColumn get weekId =>
      text().references(ProgramWeeks, #id, onDelete: KeyAction.cascade)();
  TextColumn get programId =>
      text().references(Programs, #id, onDelete: KeyAction.cascade)();
  TextColumn get day => text()();
  TextColumn get type => text()();
  TextColumn get refId => text().nullable()();
  TextColumn get name => text().nullable()();
  TextColumn get description => text().nullable()();
  BoolColumn get completed => boolean().withDefault(const Constant(false))();

  @override
  Set<Column> get primaryKey => {id};
}

class AnalysisSessions extends Table {
  TextColumn get id => text()();
  TextColumn get name => text()();
  TextColumn get date => text()();
  TextColumn get videoPath => text().nullable()();

  @override
  Set<Column> get primaryKey => {id};
}

class Annotations extends Table {
  TextColumn get id => text()();
  TextColumn get sessionId =>
      text().references(AnalysisSessions, #id, onDelete: KeyAction.cascade)();
  RealColumn get startTime => real()();
  RealColumn get endTime => real()();
  TextColumn get name => text().nullable()();
  TextColumn get description => text().nullable()();
  TextColumn get color => text().nullable()();

  @override
  Set<Column> get primaryKey => {id};
}

class ChatSessions extends Table {
  TextColumn get id => text()();
  TextColumn get title => text().nullable()();
  TextColumn get createdAt => text()();
  TextColumn get updatedAt => text()();

  @override
  Set<Column> get primaryKey => {id};
}

class ChatMessages extends Table {
  TextColumn get id => text()();
  TextColumn get sessionId =>
      text().references(ChatSessions, #id, onDelete: KeyAction.cascade)();
  TextColumn get role => text()();
  TextColumn get content => text()();
  TextColumn get createdAt => text()();

  @override
  Set<Column> get primaryKey => {id};
}

// ---------------------------------------------------------------------------
// v2: Knowledge base chunks
// ---------------------------------------------------------------------------

/// Stores text chunks and their JSON-encoded embedding vectors.
/// Used for Retrieval-Augmented Generation (RAG) in the AI chat.
class KnowledgeChunks extends Table {
  /// UUID for this individual chunk.
  TextColumn get id => text()();

  /// All chunks from the same `addNote()` call share this ID.
  TextColumn get sourceId => text()();

  /// The raw text of the chunk (max ~500 chars).
  TextColumn get content => text()();

  /// JSON-encoded `List<double>` — the 768-dim Nomic embedding vector.
  TextColumn get embedding => text()();

  TextColumn get createdAt => text()();

  @override
  Set<Column> get primaryKey => {id};
}

// ---------------------------------------------------------------------------
// Database class
// ---------------------------------------------------------------------------

@DriftDatabase(
  tables: [
    Exercises,
    TrainingPlans,
    Programs,
    ProgramWeeks,
    ProgramWorkouts,
    AnalysisSessions,
    Annotations,
    ChatSessions,
    ChatMessages,
    KnowledgeChunks, // added in schema v2
  ],
  daos: [
    ExerciseDao,
    TrainingPlanDao,
    ProgramDao,
    AnalysisDao,
    ChatDao,
    KnowledgeChunkDao, // added in schema v2
  ],
)
class AppDatabase extends _$AppDatabase {
  AppDatabase() : super(_openConnection());

  @override
  int get schemaVersion => 2;

  @override
  MigrationStrategy get migration => MigrationStrategy(
        onUpgrade: (migrator, from, to) async {
          // v1 → v2: add knowledge chunks table
          if (from < 2) {
            await migrator.createTable(knowledgeChunks);
          }
        },
      );
}

LazyDatabase _openConnection() {
  return LazyDatabase(() async {
    final dbFolder = await getApplicationDocumentsDirectory();
    final file = File(p.join(dbFolder.path, AppConstants.databaseName));
    return NativeDatabase.createInBackground(file);
  });
}