import {
  BadRequestException,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import type { PaginationResponse } from '../../../common/http/response';
import { pickUserRelation, toListPage } from '../../../common/http/response';
import { Status } from '../../../common/value-objects/status/status';
import type {
  CreateDivisionInput,
  Division,
  UpdateDivisionInput,
} from './division';
import { isValidDivisionCode, isValidDivisionName } from './division-fields';
import { DivisionsRepository } from './divisions.repository';

export type ListDivisionsQuery = {
  readonly name?: string;
  readonly code?: string;
  readonly status?: string;
  readonly search?: string;
  readonly orderBy?: string;
  readonly orderType?: string;
  readonly page?: number;
  readonly limit?: number;
  readonly offset?: number;
};

const VISIBLE_FIELDS = [
  'id',
  'name',
  'code',
  'status',
  'createdAt',
  'updatedAt',
  'createdBy',
  'updatedBy',
] as const;

@Injectable()
export class DivisionsService {
  constructor(private readonly divisionsRepository: DivisionsRepository) {}

  async list(
    query: ListDivisionsQuery,
  ): Promise<PaginationResponse<ReturnType<DivisionsService['toListItem']>>> {
    const page = toListPage(query);
    const { data, total } = await this.divisionsRepository.list({
      name: query.name,
      code: query.code,
      status: query.status,
      search: query.search,
      orderBy: query.orderBy,
      orderType: query.orderType,
      limit: page.limit,
      offset: page.offset,
    });
    return {
      data: data.map((item) => this.toListItem(item)),
      total,
    };
  }

  async findById(
    id: string,
  ): Promise<ReturnType<DivisionsService['toListItem']>> {
    const division = await this.divisionsRepository.findById(id);
    if (!division) {
      throw new NotFoundException('Division not found');
    }
    return this.toListItem(division);
  }

  async create(input: {
    name: string;
    code: string;
    status?: string;
    userId: string;
  }): Promise<ReturnType<DivisionsService['toListItem']>> {
    const name = this.assertName(input.name);
    const code = this.assertCode(input.code);
    const created = await this.divisionsRepository.create({
      name,
      code,
      status: input.status
        ? Status.create(input.status)
        : Status.create(Status.DEFAULT),
      userId: input.userId,
    });
    return this.toListItem(created);
  }

  async update(
    id: string,
    input: {
      name?: string;
      code?: string;
      status?: unknown;
      userId: string;
    },
  ): Promise<ReturnType<DivisionsService['toListItem']>> {
    if (input.status !== undefined) {
      throw new BadRequestException('status cannot be updated via PATCH');
    }
    const payload: UpdateDivisionInput = {
      name: input.name !== undefined ? this.assertName(input.name) : undefined,
      code: input.code !== undefined ? this.assertCode(input.code) : undefined,
      userId: input.userId,
    };
    const updated = await this.divisionsRepository.update(id, payload);
    return this.toListItem(updated);
  }

  async updateStatus(
    id: string,
    statusRaw: string,
    userId: string,
  ): Promise<ReturnType<DivisionsService['toListItem']>> {
    const status = Status.create(statusRaw);
    const updated = await this.divisionsRepository.updateStatus(
      id,
      status,
      userId,
    );
    return this.toListItem(updated);
  }

  async bulkUpdateStatus(
    ids: string[],
    statusRaw: string,
    userId: string,
  ): Promise<{ updated: number }> {
    const status = Status.create(statusRaw);
    const updated = await this.divisionsRepository.bulkUpdateStatus(
      ids,
      status,
      userId,
    );
    return { updated };
  }

  async delete(id: string): Promise<void> {
    await this.divisionsRepository.delete(id);
  }

  async bulkDelete(ids: string[]): Promise<{ deleted: number }> {
    const deleted = await this.divisionsRepository.bulkDelete(ids);
    return { deleted };
  }

  async importCsv(csv: string, userId: string): Promise<{ imported: number }> {
    const lines = csv
      .split(/\r?\n/)
      .map((line) => line.trim())
      .filter((line) => line.length > 0);
    if (lines.length === 0) {
      throw new BadRequestException('CSV is empty');
    }
    if (lines.length > 501) {
      throw new BadRequestException('CSV exceeds maximum of 500 data rows');
    }

    const header = lines[0].split(',').map((h) => h.trim().toLowerCase());
    const nameIdx = header.indexOf('name');
    const codeIdx = header.indexOf('code');
    const statusIdx = header.indexOf('status');
    if (nameIdx < 0 || codeIdx < 0) {
      throw new BadRequestException('CSV must include name and code headers');
    }

    const errors: string[] = [];
    const rows: { name: string; code: string; status?: string }[] = [];
    for (let i = 1; i < lines.length; i++) {
      const cols = lines[i].split(',').map((c) => c.trim());
      const name = cols[nameIdx] ?? '';
      const code = cols[codeIdx] ?? '';
      const status = statusIdx >= 0 ? cols[statusIdx] : undefined;
      if (!name || !code) {
        errors.push(`row ${i + 1}: name and code are required`);
        continue;
      }
      if (!isValidDivisionName(name)) {
        errors.push(`row ${i + 1}: invalid name`);
        continue;
      }
      if (!isValidDivisionCode(code)) {
        errors.push(`row ${i + 1}: invalid code`);
        continue;
      }
      if (status) {
        try {
          Status.create(status);
        } catch {
          errors.push(`row ${i + 1}: invalid status`);
          continue;
        }
      }
      rows.push({ name, code, status: status || undefined });
    }

    if (errors.length > 0) {
      throw new BadRequestException({
        message: 'CSV validation failed',
        errors,
      });
    }

    const inputs: CreateDivisionInput[] = rows.map((row) => ({
      name: row.name,
      code: row.code,
      status: row.status
        ? Status.create(row.status)
        : Status.create(Status.DEFAULT),
      userId,
    }));
    await this.divisionsRepository.createMany(inputs);
    return { imported: rows.length };
  }

  toListItem(division: Division) {
    return {
      id: division.id,
      name: division.name,
      code: division.code,
      status: division.status.value,
      createdAt: division.createdAt.value,
      updatedAt: division.updatedAt.value,
      createdBy: pickUserRelation(division.createdByUser),
      updatedBy: pickUserRelation(division.updatedByUser),
    };
  }

  get visibleFields(): readonly string[] {
    return VISIBLE_FIELDS;
  }

  private assertName(raw: string): string {
    const name = raw.trim();
    if (!isValidDivisionName(name)) {
      throw new BadRequestException('Invalid division name');
    }
    return name;
  }

  private assertCode(raw: string): string {
    const code = raw.trim();
    if (!isValidDivisionCode(code)) {
      throw new BadRequestException('Invalid division code');
    }
    return code;
  }
}