import { Injectable } from '@angular/core';
import { Observable, BehaviorSubject, of } from 'rxjs';
import { map, tap, catchError } from 'rxjs/operators';
import { DataStoreService } from '../../../app/core/services/data-store.service';

// ── Interfaces ──────────────────────────────────────────────────────────────

export interface SizeRow {
  id?: string;
  sizeName: string;
  usaSize: string;
  bust: string;
  waist: string;
  hip: string;
  torso: string;
  cup: string;
}

export interface SizeTip {
  type: 'warn' | 'info';
  text: string;
}

export interface SizeChart {
  id?: string;
  name: string;
  category: string;
  unit: string;
  note: string;
  rows: SizeRow[];
  tips: SizeTip[];
}

// ── Built-in default ─────────────────────────────────────────────────────────

export const DEFAULT_SIZE_CHART: SizeChart = {
  name: 'US 女装标准尺码（泳装/瑜伽裤/运动上衣）',
  category: 'swimwear',
  unit: 'in',
  note: '美国站标准尺码对照表（泳装/瑜伽裤/运动上衣，单位：英寸）。当某 SKU 尺码不合退货占比 > 25% 时，请核对实测三围与下表偏差。',
  rows: [
    { sizeName: 'XS',  usaSize: '0-2',   bust: '32-34',    waist: '25-26.5', hip: '35-36.5',  torso: '57.5-59.5', cup: '30A/B, 32A'  },
    { sizeName: 'S',   usaSize: '4-6',   bust: '34.5-36',  waist: '27-28.5', hip: '37-38.5',  torso: '59.5-61.5', cup: '32B/C, 34B'  },
    { sizeName: 'M',   usaSize: '8-10',  bust: '36.5-38',  waist: '29-31',   hip: '39-41',    torso: '61.5-63.5', cup: '34C/D, 36B/C'},
    { sizeName: 'L',   usaSize: '12-14', bust: '38.5-40.5',waist: '32-34',   hip: '42-44',    torso: '63.5-65.5', cup: '36D, 38C/D'  },
    { sizeName: 'XL',  usaSize: '16-18', bust: '41-43',    waist: '35-37',   hip: '45-47',    torso: '65.5-67.5', cup: '38DD, 40C/D' },
    { sizeName: 'XXL', usaSize: '20-22', bust: '43.5-45.5',waist: '37.5-39', hip: '47.5-49.5',torso: '67.5-69.5', cup: '40DD, 42C/D' }
  ],
  tips: [
    { type: 'warn', text: '退货预警：若「尺码偏小」退货 > 25%，优先检查胸围实测 vs 标准偏差是否超 0.5 in' },
    { type: 'info', text: '版型选型：高腰全包（安全感+防透）→ 对照腰围标准；常规下装 → 对照臀围标准' },
    { type: 'info', text: '新品迭代：每批新品上市后 30 天追踪尺码退货率，偏差 > 0.5 in 触发改版' }
  ]
};

const PARSE_CLASS = 'SizeChartKnowledge';

// ── Service ──────────────────────────────────────────────────────────────────

/**
 * @description 尺码表知识库服务（可供全局任意页面注入使用）
 *
 * 数据存储在 Parse `SizeChartKnowledge` 表；无数据时自动降级到内置默认表。
 *
 * 典型用法：
 *   constructor(private sizeChartService: SizeChartService) {}
 *   this.sizeChartService.getCharts().subscribe(charts => ...);
 *   this.sizeChartService.saveChart(chart).subscribe(saved => ...);
 */
@Injectable({ providedIn: 'root' })
export class SizeChartService {
  private cache$ = new BehaviorSubject<SizeChart[]>([]);

  constructor(private dataStore: DataStoreService) {}

  // ── 订阅缓存（实时更新）─────────────────────────────
  get charts$(): Observable<SizeChart[]> {
    return this.cache$.asObservable();
  }

  // ── 查询全部尺码表（加载后自动写入缓存）─────────────
  getCharts(): Observable<SizeChart[]> {
    return this.dataStore.query(PARSE_CLASS, {}, { limit: 100 }).pipe(
      map(rows => rows.length ? rows.map(r => this.fromRow(r)) : [DEFAULT_SIZE_CHART]),
      tap(charts => this.cache$.next(charts)),
      catchError(() => {
        const fallback = [DEFAULT_SIZE_CHART];
        this.cache$.next(fallback);
        return of(fallback);
      })
    );
  }

  // ── 取单张表 ──────────────────────────────────────
  getChart(id: string): Observable<SizeChart | null> {
    return this.dataStore.query(PARSE_CLASS, { objectId: id }, { limit: 1 }).pipe(
      map(rows => rows.length ? this.fromRow(rows[0]) : null),
      catchError(() => of(null))
    );
  }

  // ── 新建或更新 ────────────────────────────────────
  saveChart(chart: SizeChart): Observable<SizeChart> {
    const payload: Record<string, any> = {
      name:     chart.name,
      category: chart.category,
      unit:     chart.unit,
      note:     chart.note,
      rows:     JSON.stringify(chart.rows),
      tips:     JSON.stringify(chart.tips)
    };
    if (chart.id) payload['objectId'] = chart.id;

    return this.dataStore.save(PARSE_CLASS, payload, chart.id ? 'objectId' : undefined).pipe(
      map((saved: any) => {
        const result: SizeChart = { ...chart, id: saved?.objectId ?? chart.id };
        this.updateCache(result);
        return result;
      }),
      catchError(() => of(chart))
    );
  }

  // ── 删除 ─────────────────────────────────────────
  deleteChart(id: string): Observable<void> {
    return this.dataStore.delete(PARSE_CLASS, id).pipe(
      tap(() => this.cache$.next(this.cache$.value.filter(c => c.id !== id))),
      map(() => void 0),
      catchError(() => of(void 0))
    );
  }

  // ── CSV 导入（返回解析后的行数组，由调用方决定写入哪张表）─
  parseCsv(csvText: string): SizeRow[] {
    const lines = csvText.trim().split('\n').filter(l => l.trim());
    if (lines.length < 2) return [];
    const headers = lines[0].split(',').map(h => h.trim().toLowerCase());
    return lines.slice(1).map(line => {
      const cols = line.split(',').map(c => c.trim().replace(/^"|"$/g, ''));
      const cell = (key: string[]) => {
        for (const k of key) {
          const i = headers.indexOf(k);
          if (i >= 0 && cols[i]) return cols[i];
        }
        return '';
      };
      return {
        sizeName: cell(['size', 'sizename', 'size_name', '尺码']),
        usaSize:  cell(['usa', 'usasize', 'usa_size', 'usa码']),
        bust:     cell(['bust', '胸围']),
        waist:    cell(['waist', '腰围']),
        hip:      cell(['hip', '臀围']),
        torso:    cell(['torso', '躯干']),
        cup:      cell(['cup', '罩杯'])
      };
    }).filter(r => r.sizeName);
  }

  // ── 获取默认表（其他页面可直接取同步引用）───────────
  getDefaultChart(): SizeChart {
    return { ...DEFAULT_SIZE_CHART };
  }

  // ── 工具：生成空行 ────────────────────────────────
  newEmptyRow(): SizeRow {
    return { sizeName: '', usaSize: '', bust: '', waist: '', hip: '', torso: '', cup: '' };
  }

  // ── 深克隆一张表（用于编辑前创建副本）────────────────
  cloneChart(chart: SizeChart): SizeChart {
    return JSON.parse(JSON.stringify(chart));
  }

  // ── 生成 AI 可读的尺码知识库上下文块 ────────────────
  /**
   * 将尺码表数组序列化为 Markdown 格式的知识块，可直接嵌入 AI Prompt。
   * 如果传入空数组，自动降级到内置默认表。
   */
  formatForAI(charts: SizeChart[]): string {
    const list = charts.length ? charts : [DEFAULT_SIZE_CHART];
    const sections = list.map(chart => {
      const unit = chart.unit || 'in';
      const header = `### 【${chart.name}】（单位：${unit}，品类：${chart.category || '通用'}）`;
      const note = chart.note ? `> ${chart.note}\n` : '';

      // 表格
      const tableHeader = `| 尺码 | 美码 | 胸围 | 腰围 | 臀围 | 躯干长 | 罩杯 |`;
      const tableSep   = `|------|------|------|------|------|--------|------|`;
      const tableRows  = (chart.rows || []).map(r =>
        `| ${r.sizeName} | ${r.usaSize} | ${r.bust} | ${r.waist} | ${r.hip} | ${r.torso} | ${r.cup} |`
      ).join('\n');

      // 使用提示
      const tips = (chart.tips || []).map(t =>
        `- ${t.type === 'warn' ? '⚠️' : 'ℹ️'} ${t.text}`
      ).join('\n');

      return [header, note, tableHeader, tableSep, tableRows, tips ? '\n**使用提示：**\n' + tips : '']
        .filter(s => s.trim()).join('\n');
    });

    return [
      '---',
      '## 📐 尺码知识库（请在涉及尺码、版型、退货相关优化时优先参照此标准）',
      ...sections,
      '---'
    ].join('\n\n');
  }

  // ── 内部 ─────────────────────────────────────────
  private fromRow(r: any): SizeChart {
    return {
      id:       r.objectId,
      name:     r.name     ?? '',
      category: r.category ?? '',
      unit:     r.unit     ?? 'in',
      note:     r.note     ?? '',
      rows:     this.safeJson(r.rows, []),
      tips:     this.safeJson(r.tips, [])
    };
  }

  private safeJson(val: any, fallback: any): any {
    if (!val) return fallback;
    if (typeof val === 'object') return val;
    try { return JSON.parse(val); } catch { return fallback; }
  }

  private updateCache(chart: SizeChart): void {
    const list = [...this.cache$.value];
    const idx = list.findIndex(c => c.id === chart.id);
    idx >= 0 ? (list[idx] = chart) : list.push(chart);
    this.cache$.next(list);
  }
}