import {
  ConflictException,
  Injectable,
  NotFoundException,
  OnModuleInit,
  Optional,
  UnauthorizedException,
  UnprocessableEntityException,
} from '@nestjs/common';
import { JwtService } from '@nestjs/jwt';
import { InjectDataSource } from '@nestjs/typeorm';
import * as bcrypt from 'bcrypt';
import { DataSource } from 'typeorm';
import { ADMIN_AUTH_CONFIG } from '@config/app.config';
import { PaginatedResponse } from '@app/common/paginated-response.dto';
import { AdminLoginDto, CreateAdminUserDto, CreatePermissionDto, CreateRoleDto, UpdateAdminProfileDto } from './admin.dto';
import { AdminUser } from './admin-user.entity';
import { Permission } from './permission.entity';
import { Role } from './role.entity';
import {
  AdminUserRecord,
  AdminUserView,
  PermissionRecord,
  RoleRecord,
} from './admin.types';

interface PaginationInput {
  page: number;
  pageSize: number;
}

@Injectable()
export class AdminService implements OnModuleInit {
  private permissionSequence = 1;
  private roleSequence = 1;
  private adminSequence = 1;
  private readonly permissions: PermissionRecord[] = [];
  private readonly roles: RoleRecord[] = [];
  private readonly admins: AdminUserRecord[] = [];

  constructor(
    private readonly jwtService: JwtService,
    @Optional()
    @InjectDataSource()
    readonly dataSource?: DataSource,
  ) {
    if (!this.hasDatabase()) {
      this.seedMemory();
    }
  }

  async onModuleInit() {
    if (this.hasDatabase()) {
      await this.seedDatabase();
      await this.loadDatabaseRecords();
    }
  }

  async login(dto: AdminLoginDto) {
    const admin = this.admins.find((item) => item.username === dto.username);
    if (
      !admin ||
      admin.status !== 'active' ||
      !bcrypt.compareSync(dto.password, admin.passwordHash)
    ) {
      throw new UnauthorizedException('Invalid username or password');
    }

    return {
      accessToken: await this.jwtService.signAsync({
        sub: admin.id,
        username: admin.username,
        type: 'admin',
      }),
      admin: this.toAdminView(admin),
    };
  }

  async createPermission(dto: CreatePermissionDto): Promise<PermissionRecord> {
    if (this.hasDatabase()) {
      const repository = this.dataSource.getRepository(Permission);
      if (await repository.findOne({ where: { code: dto.code } })) {
        throw new ConflictException('Permission code already exists');
      }
      const saved = await repository.save(repository.create(dto));
      await this.loadDatabaseRecords();
      return this.toPermissionRecord(saved);
    }

    if (this.permissions.some((item) => item.code === dto.code)) {
      throw new ConflictException('Permission code already exists');
    }

    const now = new Date().toISOString();
    const permission: PermissionRecord = {
      id: this.permissionSequence++,
      code: dto.code,
      name: dto.name,
      description: dto.description,
      createdAt: now,
      updatedAt: now,
    };

    this.permissions.push(permission);
    return permission;
  }

  async listPermissions(
    pagination: PaginationInput,
  ): Promise<PaginatedResponse<PermissionRecord>> {
    if (this.hasDatabase()) {
      await this.loadDatabaseRecords();
    }

    return this.paginate([...this.permissions], pagination);
  }

  async createRole(dto: CreateRoleDto): Promise<RoleRecord> {
    if (this.hasDatabase()) {
      const repository = this.dataSource.getRepository(Role);
      if (await repository.findOne({ where: { code: dto.code } })) {
        throw new ConflictException('Role code already exists');
      }
      const saved = await repository.save(
        repository.create({
          code: dto.code,
          name: dto.name,
          description: dto.description,
          permissionIds: dto.permissionIds ?? [],
        }),
      );
      await this.loadDatabaseRecords();
      return this.roles.find((role) => role.id === Number(saved.id)) as RoleRecord;
    }

    if (this.roles.some((item) => item.code === dto.code)) {
      throw new ConflictException('Role code already exists');
    }

    const now = new Date().toISOString();
    const permissionIds = dto.permissionIds ?? [];
    const role: RoleRecord = {
      id: this.roleSequence++,
      code: dto.code,
      name: dto.name,
      description: dto.description,
      permissionIds,
      permissions: this.permissions.filter((permission) =>
        permissionIds.includes(permission.id),
      ),
      createdAt: now,
      updatedAt: now,
    };

    this.roles.push(role);
    return role;
  }

  async listRoles(pagination: PaginationInput): Promise<PaginatedResponse<RoleRecord>> {
    if (this.hasDatabase()) {
      await this.loadDatabaseRecords();
    }

    return this.paginate([...this.roles], pagination);
  }

  async updateRolePermissions(id: number, permissionIds: number[]): Promise<RoleRecord> {
    if (this.hasDatabase()) {
      const repository = this.dataSource.getRepository(Role);
      const role = await repository.findOne({ where: { id } });
      if (!role) {
        throw new NotFoundException('Role not found');
      }
      role.permissionIds = [...new Set(permissionIds)];
      await repository.save(role);
      await this.loadDatabaseRecords();
      return this.roles.find((item) => item.id === id) as RoleRecord;
    }

    const role = this.roles.find((item) => item.id === id);
    if (!role) {
      throw new NotFoundException('Role not found');
    }

    const uniquePermissionIds = [...new Set(permissionIds)];
    role.permissionIds = uniquePermissionIds;
    role.permissions = this.permissions.filter((permission) =>
      uniquePermissionIds.includes(permission.id),
    );
    role.updatedAt = new Date().toISOString();
    return role;
  }

  async createAdminUser(dto: CreateAdminUserDto): Promise<AdminUserView> {
    if (this.hasDatabase()) {
      const repository = this.dataSource.getRepository(AdminUser);
      if (await repository.findOne({ where: { username: dto.username } })) {
        throw new ConflictException('Admin username already exists');
      }
      const saved = await repository.save(
        repository.create({
          username: dto.username,
          passwordHash: bcrypt.hashSync(dto.password, 10),
          nickname: dto.nickname,
          email: dto.email,
          status: 'active',
          isSuperAdmin: false,
          roleIds: dto.roleIds ?? [],
        }),
      );
      await this.loadDatabaseRecords();
      return this.toAdminView(
        this.admins.find((admin) => admin.id === Number(saved.id)) as AdminUserRecord,
      );
    }

    if (this.admins.some((item) => item.username === dto.username)) {
      throw new ConflictException('Admin username already exists');
    }

    const now = new Date().toISOString();
    const admin: AdminUserRecord = {
      id: this.adminSequence++,
      username: dto.username,
      passwordHash: bcrypt.hashSync(dto.password, 10),
      nickname: dto.nickname,
      email: dto.email,
      status: 'active',
      isSuperAdmin: false,
      roleIds: dto.roleIds ?? [],
      createdAt: now,
      updatedAt: now,
    };

    this.admins.push(admin);
    return this.toAdminView(admin);
  }

  async listAdminUsers(
    pagination: PaginationInput,
  ): Promise<PaginatedResponse<AdminUserView>> {
    if (this.hasDatabase()) {
      await this.loadDatabaseRecords();
    }

    return this.paginate(
      this.admins.map((admin) => this.toAdminView(admin)),
      pagination,
    );
  }

  async updateAdminStatus(
    id: number,
    status: 'active' | 'disabled',
  ): Promise<AdminUserView> {
    if (this.hasDatabase()) {
      const repository = this.dataSource.getRepository(AdminUser);
      const admin = await repository.findOne({ where: { id } });
      if (!admin) {
        throw new NotFoundException('Admin user not found');
      }
      admin.status = status;
      await repository.save(admin);
      await this.loadDatabaseRecords();
      return this.toAdminView(this.findAdminById(id) as AdminUserRecord);
    }

    const admin = this.findAdminById(id);
    if (!admin) {
      throw new NotFoundException('Admin user not found');
    }

    admin.status = status;
    admin.updatedAt = new Date().toISOString();
    return this.toAdminView(admin);
  }

  async updateAdminRoles(id: number, roleIds: number[]): Promise<AdminUserView> {
    if (this.hasDatabase()) {
      const repository = this.dataSource.getRepository(AdminUser);
      const admin = await repository.findOne({ where: { id } });
      if (!admin) {
        throw new NotFoundException('Admin user not found');
      }
      admin.roleIds = [...new Set(roleIds)];
      await repository.save(admin);
      await this.loadDatabaseRecords();
      return this.toAdminView(this.findAdminById(id) as AdminUserRecord);
    }

    const admin = this.findAdminById(id);
    if (!admin) {
      throw new NotFoundException('Admin user not found');
    }

    admin.roleIds = [...new Set(roleIds)];
    admin.updatedAt = new Date().toISOString();
    return this.toAdminView(admin);
  }

  async updateProfile(
    adminId: number,
    dto: UpdateAdminProfileDto,
  ): Promise<AdminUserView> {
    if (this.hasDatabase()) {
      const repository = this.dataSource.getRepository(AdminUser);
      const admin = await repository.findOne({ where: { id: adminId } });
      if (!admin) {
        throw new NotFoundException('Admin user not found');
      }
      admin.nickname = dto.nickname;
      admin.email = dto.email;
      await repository.save(admin);
      await this.loadDatabaseRecords();
      return this.toAdminView(this.findAdminById(adminId) as AdminUserRecord);
    }

    const admin = this.findAdminById(adminId);
    if (!admin) {
      throw new NotFoundException('Admin user not found');
    }

    admin.nickname = dto.nickname;
    admin.email = dto.email;
    admin.updatedAt = new Date().toISOString();
    return this.toAdminView(admin);
  }

  async changePassword(
    adminId: number,
    oldPassword: string,
    newPassword: string,
  ): Promise<Record<string, never>> {
    if (this.hasDatabase()) {
      const repository = this.dataSource.getRepository(AdminUser);
      const admin = await repository.findOne({ where: { id: adminId } });
      if (!admin) {
        throw new NotFoundException('Admin user not found');
      }
      if (!bcrypt.compareSync(oldPassword, admin.passwordHash)) {
        throw new UnprocessableEntityException('Old password is incorrect');
      }
      admin.passwordHash = bcrypt.hashSync(newPassword, 10);
      await repository.save(admin);
      await this.loadDatabaseRecords();
      return {};
    }

    const admin = this.findAdminById(adminId);
    if (!admin) {
      throw new NotFoundException('Admin user not found');
    }

    if (!bcrypt.compareSync(oldPassword, admin.passwordHash)) {
      throw new UnprocessableEntityException('Old password is incorrect');
    }

    admin.passwordHash = bcrypt.hashSync(newPassword, 10);
    admin.updatedAt = new Date().toISOString();
    return {};
  }

  findAdminById(id: number) {
    return this.admins.find((admin) => admin.id === id);
  }

  getPermissionCodesForAdmin(adminId: number) {
    const admin = this.findAdminById(adminId);
    if (!admin) {
      return [];
    }

    if (admin.isSuperAdmin) {
      return ['*'];
    }

    return this.roles
      .filter((role) => admin.roleIds.includes(role.id))
      .flatMap((role) => role.permissions.map((permission) => permission.code));
  }

  toAdminView(admin: AdminUserRecord): AdminUserView {
    const roles = this.roles.filter((role) => admin.roleIds.includes(role.id));
    const permissions: PermissionRecord[] | ['*'] = admin.isSuperAdmin
      ? ['*']
      : roles.flatMap((role) => role.permissions);

    return {
      id: admin.id,
      username: admin.username,
      nickname: admin.nickname,
      email: admin.email,
      status: admin.status,
      isSuperAdmin: admin.isSuperAdmin,
      roles,
      permissions,
      createdAt: admin.createdAt,
      updatedAt: admin.updatedAt,
    };
  }

  private seedMemory() {
    const codes = [
      ['permission:read', '查看权限'],
      ['permission:create', '创建权限'],
      ['role:read', '查看角色'],
      ['role:create', '创建角色'],
      ['role:update', '更新角色'],
      ['admin-user:read', '查看人员'],
      ['admin-user:create', '创建人员'],
      ['admin-user:update', '更新人员'],
      ['user:read', '查看用户'],
      ['user:update', '更新用户'],
      ['channel:read', '查看频道'],
      ['channel:create', '创建频道'],
      ['channel:update', '更新频道'],
      ['channel:delete', '删除频道'],
      ['drama:read', '查看短剧'],
      ['drama:create', '创建短剧'],
      ['drama:update', '更新短剧'],
      ['drama:delete', '删除短剧'],
      ['episode:create', '创建剧集'],
      ['episode:update', '更新剧集'],
      ['media:read', '查看媒体'],
      ['media:create', '创建媒体'],
      ['data:read', '查看数据'],
      ['data:sync', '同步数据'],
      ['payment:read', '查看支付记录'],
      ['log:read', '查看日志'],
    ];

    for (const [code, name] of codes) {
      this.createPermission({ code, name });
    }

    const now = new Date().toISOString();
    this.admins.push({
      id: this.adminSequence++,
      username: ADMIN_AUTH_CONFIG.username,
      passwordHash: bcrypt.hashSync(ADMIN_AUTH_CONFIG.password, 10),
      nickname: 'Super Admin',
      email: ADMIN_AUTH_CONFIG.email,
      status: 'active',
      isSuperAdmin: true,
      roleIds: [],
      createdAt: now,
      updatedAt: now,
    });
  }

  private hasDatabase(): this is this & { dataSource: DataSource } {
    return Boolean(this.dataSource?.isInitialized);
  }

  private async seedDatabase() {
    const dataSource = this.dataSource as DataSource;
    const permissionRepository = dataSource.getRepository(Permission);
    for (const [code, name] of this.permissionSeeds()) {
      const existing = await permissionRepository.findOne({ where: { code } });
      if (!existing) {
        await permissionRepository.save(
          permissionRepository.create({ code, name }),
        );
      } else if (existing.name !== name) {
        existing.name = name;
        await permissionRepository.save(existing);
      }
    }

    const adminRepository = dataSource.getRepository(AdminUser);
    const username = ADMIN_AUTH_CONFIG.username;
    const existingAdmin = await adminRepository.findOne({ where: { username } });
    if (!existingAdmin) {
      await adminRepository.save(
        adminRepository.create({
          username,
          passwordHash: bcrypt.hashSync(ADMIN_AUTH_CONFIG.password, 10),
          nickname: 'Super Admin',
          email: ADMIN_AUTH_CONFIG.email,
          status: 'active',
          isSuperAdmin: true,
          roleIds: [],
        }),
      );
    }
  }

  private async loadDatabaseRecords() {
    const dataSource = this.dataSource as DataSource;
    const permissions = await dataSource.getRepository(Permission).find({
      order: { id: 'ASC' },
    });
    this.permissions.splice(
      0,
      this.permissions.length,
      ...permissions.map((permission) => this.toPermissionRecord(permission)),
    );

    const roles = await dataSource.getRepository(Role).find({
      order: { id: 'ASC' },
    });
    this.roles.splice(
      0,
      this.roles.length,
      ...roles.map((role) => this.toRoleRecord(role)),
    );

    const admins = await dataSource.getRepository(AdminUser).find({
      order: { id: 'ASC' },
    });
    this.admins.splice(
      0,
      this.admins.length,
      ...admins.map((admin) => this.toAdminRecord(admin)),
    );
  }

  private permissionSeeds() {
    return [
      ['permission:read', '查看权限'],
      ['permission:create', '创建权限'],
      ['role:read', '查看角色'],
      ['role:create', '创建角色'],
      ['role:update', '更新角色'],
      ['admin-user:read', '查看人员'],
      ['admin-user:create', '创建人员'],
      ['admin-user:update', '更新人员'],
      ['user:read', '查看用户'],
      ['user:update', '更新用户'],
      ['drama:read', '查看短剧'],
      ['drama:create', '创建短剧'],
      ['drama:update', '更新短剧'],
      ['episode:create', '创建剧集'],
      ['episode:update', '更新剧集'],
      ['media:read', '查看媒体'],
      ['media:create', '创建媒体'],
      ['data:read', '查看数据'],
      ['data:sync', '同步数据'],
      ['payment:read', '查看支付记录'],
      ['log:read', '查看日志'],
    ] as const;
  }

  private toPermissionRecord(permission: Permission): PermissionRecord {
    return {
      id: Number(permission.id),
      code: permission.code,
      name: permission.name,
      description: permission.description,
      createdAt: permission.createdAt?.toISOString?.() ?? new Date().toISOString(),
      updatedAt: permission.updatedAt?.toISOString?.() ?? new Date().toISOString(),
    };
  }

  private toRoleRecord(role: Role): RoleRecord {
    const permissionIds = role.permissionIds ?? [];
    return {
      id: Number(role.id),
      code: role.code,
      name: role.name,
      description: role.description,
      permissionIds,
      permissions: this.permissions.filter((permission) =>
        permissionIds.includes(permission.id),
      ),
      createdAt: role.createdAt?.toISOString?.() ?? new Date().toISOString(),
      updatedAt: role.updatedAt?.toISOString?.() ?? new Date().toISOString(),
    };
  }

  private toAdminRecord(admin: AdminUser): AdminUserRecord {
    return {
      id: Number(admin.id),
      username: admin.username,
      passwordHash: admin.passwordHash,
      nickname: admin.nickname,
      email: admin.email,
      status: admin.status as 'active' | 'disabled',
      isSuperAdmin: admin.isSuperAdmin,
      roleIds: admin.roleIds ?? [],
      createdAt: admin.createdAt?.toISOString?.() ?? new Date().toISOString(),
      updatedAt: admin.updatedAt?.toISOString?.() ?? new Date().toISOString(),
    };
  }

  private paginate<T>(
    records: T[],
    input: PaginationInput,
  ): PaginatedResponse<T> {
    const page = Math.max(input.page, 1);
    const pageSize = Math.min(Math.max(input.pageSize, 1), 100);
    const start = (page - 1) * pageSize;

    return {
      list: records.slice(start, start + pageSize),
      pagination: {
        page,
        pageSize,
        total: records.length,
      },
    };
  }
}