import { v4 as uuidv4 } from 'uuid';
import {
  User,
  Medication,
  UserSettings,
  TakenDoses,
  CustomReminder,
  CouchDBDocument,
  UserRole,
} from '../../types';
import { AccountStatus } from '../auth/auth.constants';
import { DatabaseStrategy, DatabaseError } from './types';
import { databaseConfig } from '../../config/unified.config';
import { logger } from '../logging';

export class ProductionDatabaseStrategy implements DatabaseStrategy {
  private baseUrl: string;
  private auth: string;

  constructor() {
    // Get CouchDB configuration from unified config
    const dbConfig = databaseConfig;

    this.baseUrl = dbConfig.url;
    this.auth = btoa(`${dbConfig.username}:${dbConfig.password}`);

    logger.db.query('Initializing production database strategy', {
      url: dbConfig.url,
      username: dbConfig.username,
    });

    // Initialize databases
    this.initializeDatabases();
  }

  private async initializeDatabases(): Promise<void> {
    const databases = [
      'users',
      'medications',
      'settings',
      'taken_doses',
      'reminders',
    ];

    for (const dbName of databases) {
      try {
        await this.createDatabaseIfNotExists(dbName);
      } catch (error) {
        logger.db.error(
          `Failed to initialize database ${dbName}`,
          error as Error
        );
      }
    }
  }

  private async createDatabaseIfNotExists(dbName: string): Promise<void> {
    try {
      // Check if database exists
      const response = await fetch(`${this.baseUrl}/${dbName}`, {
        method: 'HEAD',
        headers: {
          Authorization: `Basic ${this.auth}`,
        },
      });

      if (response.status === 404) {
        // Database doesn't exist, create it
        const createResponse = await fetch(`${this.baseUrl}/${dbName}`, {
          method: 'PUT',
          headers: {
            Authorization: `Basic ${this.auth}`,
            'Content-Type': 'application/json',
          },
        });

        if (!createResponse.ok) {
          throw new DatabaseError(
            `Failed to create database ${dbName}`,
            createResponse.status
          );
        }
      }
    } catch (error) {
      if (error instanceof DatabaseError) {
        throw error;
      }
      throw new DatabaseError(
        `Database initialization failed for ${dbName}`,
        500
      );
    }
  }

  private async makeRequest<T>(
    method: string,
    path: string,
    body?: unknown
  ): Promise<T> {
    const url = `${this.baseUrl}${path}`;
    const headers: Record<string, string> = {
      Authorization: `Basic ${this.auth}`,
      'Content-Type': 'application/json',
    };

    const config: RequestInit = {
      method,
      headers,
    };

    if (body) {
      config.body = JSON.stringify(body);
    }

    try {
      const response = await fetch(url, config);

      if (!response.ok) {
        const errorText = await response.text();
        throw new DatabaseError(
          `HTTP ${response.status}: ${errorText}`,
          response.status
        );
      }

      return await response.json();
    } catch (error) {
      if (error instanceof DatabaseError) {
        throw error;
      }
      throw new DatabaseError(`Network error: ${error}`, 500);
    }
  }

  private async getDoc<T extends CouchDBDocument>(
    dbName: string,
    id: string
  ): Promise<T | null> {
    try {
      return await this.makeRequest<T>('GET', `/${dbName}/${id}`);
    } catch (error) {
      if (error instanceof DatabaseError && error.status === 404) {
        return null;
      }
      throw error;
    }
  }

  private async putDoc<T extends CouchDBDocument>(
    dbName: string,
    doc: T
  ): Promise<T> {
    const response = await this.makeRequest<{ id: string; rev: string }>(
      'PUT',
      `/${dbName}/${doc._id}`,
      doc
    );

    return {
      ...doc,
      _rev: response.rev,
    };
  }

  private async deleteDoc(
    dbName: string,
    id: string,
    rev: string
  ): Promise<boolean> {
    try {
      await this.makeRequest('DELETE', `/${dbName}/${id}?rev=${rev}`);
      return true;
    } catch (error) {
      if (error instanceof DatabaseError && error.status === 404) {
        return false;
      }
      throw error;
    }
  }

  private async queryByKey<T>(
    dbName: string,
    startKey: string,
    endKey?: string
  ): Promise<T[]> {
    const params = new URLSearchParams({
      startkey: JSON.stringify(startKey),
      include_docs: 'true',
    });

    if (endKey) {
      params.append('endkey', JSON.stringify(endKey));
    }

    const response = await this.makeRequest<{
      rows: Array<{ doc: T }>;
    }>('GET', `/${dbName}/_all_docs?${params}`);

    return response.rows.map(row => row.doc);
  }

  // User operations
  async createUser(user: Omit<User, '_id' | '_rev'>): Promise<User> {
    const newUser: User = {
      ...user,
      _id: uuidv4(),
      _rev: '', // Will be set by CouchDB
      status: user.status || AccountStatus.ACTIVE,
      role: user.role || UserRole.USER,
      createdAt: user.createdAt || new Date(),
    };

    return this.putDoc('users', newUser);
  }

  async updateUser(user: User): Promise<User> {
    return this.putDoc('users', user);
  }

  async getUserById(id: string): Promise<User | null> {
    return this.getDoc<User>('users', id);
  }

  async findUserByEmail(email: string): Promise<User | null> {
    const response = await this.makeRequest<{
      rows: Array<{ doc: User }>;
    }>('POST', '/users/_find', {
      selector: { email },
      limit: 1,
    });

    return response.rows[0]?.doc || null;
  }

  async deleteUser(id: string): Promise<boolean> {
    const user = await this.getDoc<User>('users', id);
    if (!user) {
      return false;
    }
    return this.deleteDoc('users', id, user._rev);
  }

  async getAllUsers(): Promise<User[]> {
    const response = await this.makeRequest<{
      rows: Array<{ doc: User }>;
    }>('GET', '/users/_all_docs?include_docs=true');

    return response.rows.map(row => row.doc);
  }

  // Medication operations
  async createMedication(
    userId: string,
    medication: Omit<Medication, '_id' | '_rev'>
  ): Promise<Medication> {
    const newMedication: Medication = {
      ...medication,
      _id: `${userId}-med-${uuidv4()}`,
      _rev: '',
    };

    return this.putDoc('medications', newMedication);
  }

  async updateMedication(medication: Medication): Promise<Medication> {
    return this.putDoc('medications', medication);
  }

  async getMedications(userId: string): Promise<Medication[]> {
    return this.queryByKey<Medication>(
      'medications',
      `${userId}-med-`,
      `${userId}-med-\ufff0`
    );
  }

  async deleteMedication(id: string): Promise<boolean> {
    const medication = await this.getDoc<Medication>('medications', id);
    if (!medication) {
      return false;
    }
    return this.deleteDoc('medications', id, medication._rev);
  }

  // User settings operations
  async getUserSettings(userId: string): Promise<UserSettings> {
    const existing = await this.getDoc<UserSettings>('settings', userId);
    if (existing) {
      return existing;
    }

    // Create default settings if none exist
    const defaultSettings: UserSettings = {
      _id: userId,
      _rev: '',
      notificationsEnabled: true,
      hasCompletedOnboarding: false,
    };

    return this.putDoc('settings', defaultSettings);
  }

  async updateUserSettings(settings: UserSettings): Promise<UserSettings> {
    return this.putDoc('settings', settings);
  }

  // Taken doses operations
  async getTakenDoses(userId: string): Promise<TakenDoses> {
    const existing = await this.getDoc<TakenDoses>('taken_doses', userId);
    if (existing) {
      return existing;
    }

    // Create default taken doses record if none exists
    const defaultTakenDoses: TakenDoses = {
      _id: userId,
      _rev: '',
      doses: {},
    };

    return this.putDoc('taken_doses', defaultTakenDoses);
  }

  async updateTakenDoses(takenDoses: TakenDoses): Promise<TakenDoses> {
    return this.putDoc('taken_doses', takenDoses);
  }

  // Custom reminders operations
  async createCustomReminder(
    userId: string,
    reminder: Omit<CustomReminder, '_id' | '_rev'>
  ): Promise<CustomReminder> {
    const newReminder: CustomReminder = {
      ...reminder,
      _id: `${userId}-reminder-${uuidv4()}`,
      _rev: '',
    };

    return this.putDoc('reminders', newReminder);
  }

  async updateCustomReminder(
    reminder: CustomReminder
  ): Promise<CustomReminder> {
    return this.putDoc('reminders', reminder);
  }

  async getCustomReminders(userId: string): Promise<CustomReminder[]> {
    return this.queryByKey<CustomReminder>(
      'reminders',
      `${userId}-reminder-`,
      `${userId}-reminder-\ufff0`
    );
  }

  async deleteCustomReminder(id: string): Promise<boolean> {
    const reminder = await this.getDoc<CustomReminder>('reminders', id);
    if (!reminder) {
      return false;
    }
    return this.deleteDoc('reminders', id, reminder._rev);
  }

  // User operations with password
  async createUserWithPassword(
    email: string,
    hashedPassword: string,
    username?: string
  ): Promise<User> {
    // Check if user already exists
    const existingUser = await this.findUserByEmail(email);
    if (existingUser) {
      throw new DatabaseError('User already exists with this email', 409);
    }

    return this.createUser({
      username: username || email.split('@')[0],
      email,
      password: hashedPassword,
      emailVerified: false,
      status: AccountStatus.PENDING,
      role: UserRole.USER,
      createdAt: new Date(),
    });
  }

  async createUserFromOAuth(
    email: string,
    username: string,
    _provider: string
  ): Promise<User> {
    // Check if user already exists
    const existingUser = await this.findUserByEmail(email);
    if (existingUser) {
      // Update last login and return existing user
      return this.updateUser({
        ...existingUser,
        lastLoginAt: new Date(),
      });
    }

    return this.createUser({
      username,
      email,
      emailVerified: true, // OAuth emails are considered verified
      status: AccountStatus.ACTIVE,
      role: UserRole.USER,
      createdAt: new Date(),
      lastLoginAt: new Date(),
    });
  }
}