import { Injectable, NotFoundException } from '@nestjs/common';
import { DatabaseService } from '../db/database.service';
import { WritableDbService } from '../db/writable-db.service';
import { EDITABLE_MAP } from '../contrib/editable-fields';
import { QueryModelsDto, SORTABLE_FIELDS } from './query-models.dto';

export interface PagedResult<T> {
  total: number;
  page: number;
  pageSize: number;
  items: T[];
}

@Injectable()
export class ModelsService {
  constructor(
    private readonly database: DatabaseService,
    private readonly wdb: WritableDbService,
  ) {}

  /** 构造 WHERE 子句与绑定参数（参数化，避免注入）。*/
  private buildWhere(q: QueryModelsDto): { clause: string; params: any[] } {
    const conds: string[] = [];
    const params: any[] = [];

    if (q.category) {
      if (/^\d+$/.test(q.category)) {
        conds.push('m.category_id = ?');
        params.push(Number(q.category));
      } else {
        conds.push('c.name LIKE ?');
        params.push(`%${q.category}%`);
      }
    }
    if (q.yearFrom != null) {
      conds.push('m.first_year >= ?');
      params.push(q.yearFrom);
    }
    if (q.yearTo != null) {
      conds.push('m.first_year <= ?');
      params.push(q.yearTo);
    }
    if (q.speedMin != null) {
      conds.push('m.max_speed_value >= ?');
      params.push(q.speedMin);
    }
    if (q.speedMax != null) {
      conds.push('m.max_speed_value <= ?');
      params.push(q.speedMax);
    }
    if (q.manufacturer) {
      conds.push('m.manufacturer LIKE ?');
      params.push(`%${q.manufacturer}%`);
    }
    if (q.country) {
      conds.push('m.country_type = ?');
      params.push(q.country);
    }
    if (q.status) {
      conds.push('m.status = ?');
      params.push(q.status);
    }
    if (q.q) {
      conds.push('(m.model_code LIKE ? OR m.full_name LIKE ? OR m.series LIKE ?)');
      params.push(`%${q.q}%`, `%${q.q}%`, `%${q.q}%`);
    }
    const clause = conds.length ? `WHERE ${conds.join(' AND ')}` : '';
    return { clause, params };
  }

  list(q: QueryModelsDto): PagedResult<any> {
    const { clause, params } = this.buildWhere(q);
    const db = this.database.db;

    const total = (
      db
        .prepare(
          `SELECT COUNT(*) AS n FROM model m
           JOIN category c ON c.id = m.category_id ${clause}`,
        )
        .get(...params) as { n: number }
    ).n;

    const sort = (SORTABLE_FIELDS as readonly string[]).includes(q.sort)
      ? q.sort
      : 'first_year';
    const order = q.order === 'desc' ? 'DESC' : 'ASC';
    const offset = (q.page - 1) * q.pageSize;

    const items = db
      .prepare(
        `SELECT m.id, m.model_code, m.full_name, m.series, m.manufacturer,
                m.country, m.country_type, m.first_year, m.last_year, m.status,
                m.usage, m.max_speed_value, m.max_speed_unit,
                m.weight_value, m.weight_unit, m.axle_arrangement,
                c.name AS category, c.subcat
         FROM model m JOIN category c ON c.id = m.category_id
         ${clause}
         ORDER BY (m.${sort} IS NULL), m.${sort} ${order}, m.id ASC
         LIMIT ? OFFSET ?`,
      )
      .all(...params, q.pageSize, offset) as any[];

    // 附加共享图库封面（每个车型最早一张照片）
    if (items.length) {
      const ids = items.map((i) => i.id);
      const ph = ids.map(() => '?').join(',');
      const covers = this.wdb.db
        .prepare(
          `SELECT p.model_id, p.filename FROM photos p
           WHERE p.status='confirmed' AND p.model_id IN (${ph})
           AND p.id = (SELECT p2.id FROM photos p2
                       WHERE p2.model_id = p.model_id AND p2.status='confirmed'
                       ORDER BY p2.featured DESC, p2.id ASC LIMIT 1)`,
        )
        .all(...ids) as { model_id: number; filename: string }[];
      const map = new Map(covers.map((c) => [c.model_id, c.filename]));
      for (const it of items) {
        const f = map.get(it.id);
        it.cover_url = f ? `/uploads/${f}` : null;
      }
    }

    return { total, page: q.page, pageSize: q.pageSize, items };
  }

  getById(id: number): any {
    const db = this.database.db;
    const row: any = db
      .prepare(
        `SELECT m.*, c.name AS category, c.subcat
         FROM model m JOIN category c ON c.id = m.category_id
         WHERE m.id = ?`,
      )
      .get(id);
    if (!row) {
      throw new NotFoundException(`车型 ${id} 不存在`);
    }
    if (row.raw_json) {
      try {
        row.raw = JSON.parse(row.raw_json);
      } catch {
        row.raw = {};
      }
    }
    // 叠加众包字段覆盖（已审核通过的编辑）
    const overrides = this.wdb.db
      .prepare('SELECT field, value FROM model_overrides WHERE model_id = ?')
      .all(id) as { field: string; value: string }[];
    if (overrides.length) {
      row.overridden = [];
      for (const o of overrides) {
        const def = EDITABLE_MAP.get(o.field);
        row[o.field] =
          def?.type === 'int' ? (o.value === '' ? null : Number(o.value)) : o.value;
        row.overridden.push(o.field);
      }
    }
    return row;
  }

  /** 技术族谱：按分类→系列聚合现有车型（series 字段）。*/
  families(category?: string) {
    const rows = this.database.db
      .prepare(
        `SELECT m.id, m.model_code, m.series, m.first_year, m.last_year,
                m.country_type, m.max_speed_value, m.max_speed_unit,
                c.name AS category
         FROM model m JOIN category c ON c.id = m.category_id
         ${category ? 'WHERE c.name = ?' : ''}
         ORDER BY c.name, m.series, (m.first_year IS NULL), m.first_year`,
      )
      .all(...(category ? [category] : [])) as any[];

    const cats = new Map<string, Map<string, any[]>>();
    for (const r of rows) {
      if (!cats.has(r.category)) cats.set(r.category, new Map());
      const series = r.series || '（未归类）';
      const sm = cats.get(r.category)!;
      if (!sm.has(series)) sm.set(series, []);
      sm.get(series)!.push(r);
    }
    return [...cats.entries()].map(([cat, sm]) => ({
      category: cat,
      series: [...sm.entries()].map(([name, models]) => ({ name, models })),
    }));
  }
}