import { cuid } from '@ioc:Adonis/Core/Helpers';
import { inject, Ioc } from '@adonisjs/core/build/standalone';
import { AuthContract } from '@ioc:Adonis/Addons/Auth';

/**
 * Datatypes
 */
import RoleEnum from 'App/Datatypes/Enums/RoleEnum';
import CourseStatusEnum from 'App/Datatypes/Enums/CourseStatusEnum';
import StatusCodeEnum from 'App/Datatypes/Enums/StatusCodeEnum';
import IResponse from 'App/Datatypes/Interfaces/IResponse';
import RoleHelper from 'App/Helpers/RoleHelper';

/**
 * Repositories
 */
import CourseRepository from 'App/Repositories/CourseRepository';
import UserRepository from 'App/Repositories/UserRepository';
import CategoryRepository from 'App/Repositories/CategoryRepository';
import ImageRepository from 'App/Repositories/ImageRepository';

/**
 * Validators
 */
import CreateCourseValidator from 'App/Validators/Course/CreateCourseValidator';
import UpdateCourseValidator from 'App/Validators/Course/UpdateCourseValidator';

@inject()
export default class CourseService {
  private courseRepository: CourseRepository;

  private userRepository: UserRepository;

  private categoryRepository: CategoryRepository;

  private imageRepository: ImageRepository;

  constructor(
    courseRepository: CourseRepository,
    userRepository: UserRepository,
    categoryRepository: CategoryRepository,
    imageRepository: ImageRepository
  ) {
    this.courseRepository = courseRepository;
    this.userRepository = userRepository;
    this.categoryRepository = categoryRepository;
    this.imageRepository = imageRepository;
  }

  /**
   * Fetch list of courses
   *
   * @returns Response
   */
  public async fetchCourses(): Promise<IResponse> {
    const data = await this.courseRepository.getAll();

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Fetched all courses.',
      data,
    };
  }

  /**
   * Fetch one course by id
   *
   * @param id Course id
   * @returns Response
   */
  public async fetchCourse(id: string | number): Promise<IResponse> {
    const data = await this.courseRepository.getById(id);

    if (!data) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Fetched course.',
      data,
    };
  }

  /**
   * Fetch teacher by course id
   *
   * @param id Course id
   * @returns Response
   */
  public async fetchCourseTeacher(id: string | number): Promise<IResponse> {
    const data = await this.courseRepository.getTeacher(id);

    if (!data) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Fetched course teacher.',
      data,
    };
  }

  /**
   * Fetch category by course id
   *
   * @param id Course id
   * @returns Response
   */
  public async fetchCourseCategory(id: string | number): Promise<IResponse> {
    const data = await this.courseRepository.getCategory(id);

    if (!data) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Fetched course category.',
      data,
    };
  }

  /**
   * Fetch lessons by course id
   *
   * @param id Course id
   * @returns Response
   */
  public async fetchCourseLessons(id: string | number): Promise<IResponse> {
    const data = await this.courseRepository.getLessons(id);

    if (!data) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Fetched course lessons.',
      data,
    };
  }

  /**
   * Fetch students by course id
   *
   * @param id Course id
   * @returns Response
   */
  public async fetchCourseStudents(id: string | number): Promise<IResponse> {
    const data = await this.courseRepository.getStudents(id);

    if (!data) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Fetched course students.',
      data,
    };
  }

  /**
   * Fetch students count by course id
   *
   * @param id Course id
   * @returns Response
   */
  public async fetchStudentsCount(id: string | number): Promise<IResponse> {
    const count = await this.courseRepository.getStudentsCount(id);

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Fetched students count.',
      data: { count },
    };
  }

  /**
   * Create course
   *
   * @param data Data input
   * @returns Response
   */
  public async createCourse(data: CreateCourseValidator['schema']['props']): Promise<IResponse> {
    /**
     * Find course teacher
     */
    const teacher = await this.userRepository.getById(data.teacher_id);

    if (!teacher) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Teacher not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    const isTeacher = RoleHelper.userHasRoles(teacher.roles, [RoleEnum.TEACHER]);

    if (!isTeacher) {
      return {
        success: false,
        status: StatusCodeEnum.BAD_REQUEST,
        message: `User with id "${teacher.id}" not a teacher.`,
        data: {},
        error: {
          code: 'E_BAD_REQUEST',
        },
      };
    }

    /**
     * Find course category
     */
    const category = await this.categoryRepository.getById(data.category_id);

    if (!category) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Category not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    /* Create course */
    const course = await this.courseRepository.create(data);

    /* Create image if provided */
    if (data.background_image) {
      const bgImage = await this.imageRepository.createInCloudinaryCloud(data.background_image, cuid());
      await course.related('image').associate(bgImage);
    }

    return {
      success: true,
      status: StatusCodeEnum.CREATED,
      message: 'Course created.',
      data: course,
    };
  }

  /**
   * Delete course
   *
   * @param id Course id
   * @returns Response
   */
  public async deleteCourse(id: string | number): Promise<IResponse> {
    const course = await this.courseRepository.delete(id);

    if (!course) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    /**
     * Delete background image from course
     */
    await this.imageRepository.deleteFormCloudinaryCloud(course.bg_image_id);

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Course deleted.',
      data: course,
    };
  }

  /**
   * Update course
   *
   * @param id Course id
   * @param data Data to update
   * @returns Response
   */
  public async updateCourse(id: string | number, data: UpdateCourseValidator['schema']['props']): Promise<IResponse> {
    const course = await this.courseRepository.update(id, data);

    if (!course) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Course updated.',
      data: course,
    };
  }

  /**
   * Attach student to course
   *
   * @param id Course id
   * @param studentId Student id
   * @returns Response
   */
  public async attachUserCourse(id: string | number, studentId: string | number): Promise<IResponse> {
    const course = await this.courseRepository.getById(id);

    if (!course) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    const student = await this.userRepository.getById(studentId);

    if (!student) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Student not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    const isStudent = RoleHelper.userHasRoles(student.roles, [RoleEnum.STUDENT]);

    if (!isStudent) {
      return {
        success: false,
        status: StatusCodeEnum.BAD_REQUEST,
        message: `User cannot be added to the course without "${RoleEnum.STUDENT}" role.`,
        data: {},
        error: {
          code: 'E_BAD_REQUEST',
        },
      };
    }

    try {
      await course.related('students').attach([student.id]);
    } catch (error) {
      if (error.code === '23505') {
        return {
          success: false,
          status: StatusCodeEnum.BAD_REQUEST,
          message: 'Student already attached to that course.',
          data: {},
          error: {
            code: 'E_BAD_REQUEST',
          },
        };
      }
      throw new Error(error);
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Student attached.',
      data: {},
    };
  }

  public async detachUserCourse(id: string | number, studentId: string | number): Promise<IResponse> {
    const course = await this.courseRepository.getById(id);

    if (!course) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    const isAttached = course.students.find(student => student.id === studentId);

    if (!isAttached) {
      return {
        success: false,
        status: StatusCodeEnum.BAD_REQUEST,
        message: 'Student not attached to that course.',
        data: {},
        error: {
          code: 'E_BAD_REQUEST',
        },
      };
    }

    const student = await this.userRepository.getById(studentId);

    if (!student) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Student not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    await course.related('students').detach([student.id]);

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Student detached.',
      data: {},
    };
  }

  public async attachUserLike(id: string | number, auth: AuthContract): Promise<any> {
    const user = await auth.use('api').authenticate();
    const course = await this.courseRepository.getById(id);

    if (!course) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    try {
      await course.related('likes').attach([user.id]);
    } catch (error) {
      if (error.code === '23505') {
        return {
          success: false,
          status: StatusCodeEnum.BAD_REQUEST,
          message: 'You are already liked this course.',
          data: {},
          error: {
            code: 'E_BAD_REQUEST',
          },
        };
      }
      throw new Error(error);
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Like attached.',
      data: {},
    };
  }

  public async detachUserLike(id: string | number, auth: AuthContract): Promise<any> {
    const user = await auth.use('api').authenticate();
    const course = await this.courseRepository.getById(id);

    if (!course) {
      return {
        success: false,
        status: StatusCodeEnum.NOT_FOUND,
        message: 'Course not found.',
        data: {},
        error: {
          code: 'E_NOT_FOUND',
        },
      };
    }

    try {
      await course.related('likes').detach([user.id]);
    } catch (error) {
      throw new Error(error);
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Like detached.',
      data: {},
    };
  }

  public async setCourseStatus(id: string | number, status: CourseStatusEnum): Promise<IResponse> {
    const data = await this.courseRepository.setStatus(id, status);

    if (!data) {
      return {
        success: false,
        status: StatusCodeEnum.BAD_REQUEST,
        message: `Cannot set status for course with id "${id}"`,
        data: {},
        error: {
          code: 'E_BAD_REQUEST',
        },
      };
    }

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Status changed.',
      data: {},
    };
  }

  public async fetchCourseLikesCount(id: string | number): Promise<IResponse> {
    const count = await this.courseRepository.getLikesCount(id);

    return {
      success: true,
      status: StatusCodeEnum.OK,
      message: 'Fetched course likes count.',
      data: { count },
    };
  }
}

new Ioc().make(CourseService);