package repository

import (
	"database/sql"
	"fmt"
	"strings"
)

// ComparableShopeeSpec 是一条可用于只读对比的蝦皮正式规格。
type ComparableShopeeSpec struct {
	Color   string
	Size    string
	ParseOK bool
}

// ShopSpecSource 汇总一件蝦皮商品及其关联 PDD 商品的原始对比数据。
type ShopSpecSource struct {
	ShopeeGoodsID string
	PDDGoodsID    string
	PDDExists     bool
	PDDDeleted    bool
	PDDSKUsJSON   string
	ShopeeSpecs   []ComparableShopeeSpec
}

// ListShopSpecSources 按店铺名精确读取规格对比数据。本函数只执行 SELECT。
func ListShopSpecSources(q Execer, shopName string) ([]ShopSpecSource, error) {
	rows, err := q.Query(`
		SELECT sp.goods_id, sp.pdd_goods_id,
		       pp.goods_id, pp.deleted_at, pp.skus_json
		  FROM shopee_products sp
		  LEFT JOIN pdd_products pp ON pp.goods_id = sp.pdd_goods_id
		 WHERE sp.deleted_at IS NULL AND sp.shopee_shop_name = ?
		 ORDER BY sp.goods_id`, strings.TrimSpace(shopName))
	if err != nil {
		return nil, fmt.Errorf("读取店铺规格对比数据失败: %w", err)
	}
	defer rows.Close()

	var list []ShopSpecSource
	indexByGoodsID := make(map[string]int)
	for rows.Next() {
		var shopeeID string
		var pddID, existingPDDID, deletedAt, skusJSON sql.NullString
		if err := rows.Scan(&shopeeID, &pddID, &existingPDDID, &deletedAt, &skusJSON); err != nil {
			return nil, fmt.Errorf("解析店铺规格对比数据失败: %w", err)
		}
		list = append(list, ShopSpecSource{
			ShopeeGoodsID: shopeeID,
			PDDGoodsID:    pddID.String,
			PDDExists:     existingPDDID.Valid,
			PDDDeleted:    strings.TrimSpace(deletedAt.String) != "",
			PDDSKUsJSON:   skusJSON.String,
		})
		indexByGoodsID[shopeeID] = len(list) - 1
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("遍历店铺规格对比数据失败: %w", err)
	}
	rows.Close()

	// PDD JSON 可能很大，不能和 SKU JOIN 后重复传输。商品和规格分两次查询，
	// 每份 PDD JSON 只从数据库读取一次。
	skuRows, err := q.Query(`
		SELECT sk.goods_id, sk.color, sk.size, sk.parse_ok
		  FROM shopee_skus sk
		  JOIN shopee_products sp ON sp.goods_id = sk.goods_id
		 WHERE sp.deleted_at IS NULL AND sp.shopee_shop_name = ?
		 ORDER BY sk.goods_id, sk.sku_id`, strings.TrimSpace(shopName))
	if err != nil {
		return nil, fmt.Errorf("读取店铺正式规格失败: %w", err)
	}
	defer skuRows.Close()
	for skuRows.Next() {
		var goodsID string
		var color, size sql.NullString
		var parseOK int64
		if err := skuRows.Scan(&goodsID, &color, &size, &parseOK); err != nil {
			return nil, fmt.Errorf("解析店铺正式规格失败: %w", err)
		}
		index, exists := indexByGoodsID[goodsID]
		if !exists {
			continue
		}
		list[index].ShopeeSpecs = append(list[index].ShopeeSpecs, ComparableShopeeSpec{
			Color: color.String, Size: size.String, ParseOK: parseOK == 1,
		})
	}
	if err := skuRows.Err(); err != nil {
		return nil, fmt.Errorf("遍历店铺正式规格失败: %w", err)
	}
	return list, nil
}

// ReplaceEmptyPDDSpecs 用生成的规格骨架替换仍保持预期原值的 PDD 规格。
// expectedRaw 是乐观锁：读取后若被其他进程改过，更新返回 false，不覆盖新数据。
func ReplaceEmptyPDDSpecs(q Execer, pddGoodsID, expectedRaw, newRaw, updatedAt string) (bool, error) {
	result, err := q.Exec(`
		UPDATE pdd_products
		   SET skus_json = ?, updated_at = ?
		 WHERE goods_id = ? AND deleted_at IS NULL
		   AND COALESCE(skus_json, '') = ?`,
		newRaw, updatedAt, strings.TrimSpace(pddGoodsID), expectedRaw)
	if err != nil {
		return false, fmt.Errorf("回填 PDD 商品 %s 的规格失败: %w", pddGoodsID, err)
	}
	rows, err := result.RowsAffected()
	if err != nil {
		return false, fmt.Errorf("读取 PDD 商品 %s 的回填结果失败: %w", pddGoodsID, err)
	}
	return rows == 1, nil
}