/**
 * Pricing endpoint - Anvil 가격표 (D1 직접 조회)
 * GET /api/pricing → D1 cloud-instances-db (anvil_* 테이블)
 *
 * Anvil Regions:
 * - Tokyo 1-3 (Linode × 2 + Vultr)
 * - Osaka 1-2 (Linode + Vultr)
 * - Seoul 1 (Vultr)
 * - Singapore 1 (Linode)
 */

import { type PagesFunction } from '@cloudflare/workers-types';

interface Env {
  DB: D1Database;
}

interface AnvilPricingRow {
  instance_id: number;
  instance_name: string;
  display_name: string;
  category: string;
  vcpus: number;
  memory_gb: number;
  disk_gb: number;
  transfer_tb: number | null;
  network_gbps: number | null;
  gpu_model: string | null;
  gpu_vram_gb: number | null;
  region_id: number;
  region_name: string;
  region_display_name: string;
  country_code: string;
  source_provider: string;
  hourly_price: number;
  monthly_price: number;
}

interface TransferPricingRow {
  region_name: string;
  region_display_name: string;
  price_per_gb: number;
}

// 기본 환율 (API 실패 시 fallback)
const DEFAULT_USD_TO_KRW = 1450;

// 실시간 환율 조회 (exchangerate-api.com)
async function fetchExchangeRate(): Promise<{ rate: number; source: string }> {
  try {
    const response = await fetch('https://open.er-api.com/v6/latest/USD', {
      cf: { cacheTtl: 3600 }, // 1시간 캐시
    });

    if (!response.ok) {
      throw new Error(`Exchange rate API error: ${response.status}`);
    }

    const data = await response.json() as { rates?: { KRW?: number } };
    const rate = data.rates?.KRW;

    if (rate && rate > 0) {
      return { rate: Math.round(rate), source: 'realtime' };
    }
    throw new Error('Invalid exchange rate data');
  } catch (error) {
    console.error('[Pricing] Exchange rate fetch failed:', error);
    return { rate: DEFAULT_USD_TO_KRW, source: 'fallback' };
  }
}

const CORS_HEADERS = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Methods': 'GET, OPTIONS',
  'Access-Control-Allow-Headers': 'Content-Type',
};

export const onRequestGet: PagesFunction<Env> = async ({ env }) => {
  try {
    // 실시간 환율 조회
    const exchangeRate = await fetchExchangeRate();
    const USD_TO_KRW = exchangeRate.rate;

    // Anvil 가격 조회 (인스턴스 + 리전 + 가격 조인)
    const pricingSql = `
      SELECT
        ai.id as instance_id,
        ai.name as instance_name,
        ai.display_name,
        ai.category,
        ai.vcpus,
        ai.memory_gb,
        ai.disk_gb,
        ai.transfer_tb,
        ai.network_gbps,
        ai.gpu_model,
        ai.gpu_vram_gb,
        ar.id as region_id,
        ar.name as region_name,
        ar.display_name as region_display_name,
        ar.country_code,
        ar.source_provider,
        ap.hourly_price,
        ap.monthly_price
      FROM anvil_pricing ap
      JOIN anvil_instances ai ON ap.anvil_instance_id = ai.id
      JOIN anvil_regions ar ON ap.anvil_region_id = ar.id
      WHERE ai.active = 1 AND ar.active = 1
      ORDER BY ar.id, ap.monthly_price ASC
    `;

    // 트래픽 가격 조회
    const transferSql = `
      SELECT
        ar.name as region_name,
        ar.display_name as region_display_name,
        atp.price_per_gb
      FROM anvil_transfer_pricing atp
      JOIN anvil_regions ar ON atp.anvil_region_id = ar.id
      WHERE ar.active = 1
    `;

    const [pricingResult, transferResult] = await Promise.all([
      env.DB.prepare(pricingSql).all<AnvilPricingRow>(),
      env.DB.prepare(transferSql).all<TransferPricingRow>(),
    ]);

    // 인스턴스 변환 (프론트엔드 형식)
    const instances = pricingResult.results.map((row) => ({
      id: row.instance_name,
      instance_name: row.instance_name,
      display_name: row.display_name,
      category: row.category,
      vcpu: row.vcpus,
      memory_mb: Math.round(row.memory_gb * 1024),
      memory_gb: row.memory_gb,
      storage_gb: row.disk_gb,
      transfer_tb: row.transfer_tb,
      network_gbps: row.network_gbps,
      gpu_model: row.gpu_model,
      gpu_vram_gb: row.gpu_vram_gb,
      has_gpu: row.category === 'gpu' || row.gpu_model !== null,
      region: {
        id: row.region_id,
        name: row.region_name,
        display_name: row.region_display_name,
        country_code: row.country_code,
      },
      provider: row.source_provider,
      pricing: {
        hourly_price: row.hourly_price,
        monthly_price: row.monthly_price,
        hourly_price_krw: Math.round(row.hourly_price * USD_TO_KRW), // 1원 단위 반올림
        monthly_price_krw: Math.round(row.monthly_price * USD_TO_KRW / 500) * 500, // 500원 단위 반올림
      },
    }));

    // 트래픽 가격 변환 (리전별) - 1원 단위 반올림
    const transferPricing = transferResult.results.reduce((acc, row) => {
      acc[row.region_display_name] = {
        price_per_gb: row.price_per_gb,
        price_per_gb_krw: Math.round(row.price_per_gb * USD_TO_KRW),
      };
      return acc;
    }, {} as Record<string, { price_per_gb: number; price_per_gb_krw: number }>);

    // 리전별 카운트
    const regionCounts: Record<string, number> = {};
    for (const inst of instances) {
      const regionKey = inst.region.display_name.toLowerCase().replace(/\s+/g, '-');
      regionCounts[regionKey] = (regionCounts[regionKey] || 0) + 1;
    }

    // 사용 가능한 리전 목록 (순서 유지: Tokyo 1,2,3 → Osaka 1,2 → Seoul 1 → Singapore 1)
    const seenRegions = new Set<number>();
    const regions = instances
      .filter((i) => {
        if (seenRegions.has(i.region.id)) return false;
        seenRegions.add(i.region.id);
        return true;
      })
      .map((i) => ({
        id: i.region.display_name.toLowerCase().replace(/\s+/g, '-'),
        name: i.region.display_name,
        country_code: i.region.country_code,
        count: regionCounts[i.region.display_name.toLowerCase().replace(/\s+/g, '-')] || 0,
      }));

    return new Response(
      JSON.stringify({
        success: true,
        total: instances.length,
        exchange_rate: {
          usd_to_krw: USD_TO_KRW,
          source: exchangeRate.source,
        },
        region_counts: regionCounts,
        regions,
        transfer_pricing: transferPricing,
        instances,
      }),
      {
        headers: {
          ...CORS_HEADERS,
          'Content-Type': 'application/json',
          'Cache-Control': 'public, max-age=300', // 5분 캐시
        },
      }
    );
  } catch (error) {
    console.error('[Pricing] D1 query error:', error);
    return new Response(
      JSON.stringify({
        success: false,
        error: error instanceof Error ? error.message : 'Database query failed',
      }),
      {
        status: 500,
        headers: {
          ...CORS_HEADERS,
          'Content-Type': 'application/json',
        },
      }
    );
  }
};

export const onRequestOptions: PagesFunction<Env> = async () => {
  return new Response(null, { status: 204, headers: CORS_HEADERS });
};