package api

import (
	"database/sql"
	"net/http"
	"sort"
	"strings"

	"server/internal/schema"
)

func MetadataHandler(meta, marketing, ymt *sql.DB) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ds := r.URL.Query().Get("datasource")
		ot := r.URL.Query().Get("order_type")
		db := marketing
		if ds == "ymt" {
			db = ymt
		}

		// 从代码中获取隐藏字段列表
		hiddenFields := getHiddenFieldsFromCode(ds)

		tables := []string{}
		if ds == "ymt" {
			tables = []string{"order_info", "order_cash", "order_voucher", "order_digit", "goods_voucher_batch", "goods_voucher_subject_config", "merchant", "activity"}
		} else {
			tables = []string{"order", "order_detail", "order_cash", "order_voucher", "plan", "key_batch", "code_batch", "voucher", "voucher_batch", "merchant_key_send"}
		}
		out := []map[string]interface{}{}
		for _, tbl := range tables {
			cols := getColumns(db, tbl)
			fields := []map[string]string{}
			for _, c := range cols {
				tCanonical, fCanonical := canonicalField(ds, tbl, c.Name)
				if tCanonical == "" || fCanonical == "" {
					continue
				}

				// 检查字段是否在隐藏列表中
				if isFieldHidden(hiddenFields, tCanonical, fCanonical) {
					continue
				}

				lab := c.Comment
				if lab == "" {
					lab = fCanonical
				}
				fields = append(fields, map[string]string{"key": tCanonical + "." + fCanonical, "field": fCanonical, "label": lab})
			}
			tDisplay := displayTable(ds, tbl)
			out = append(out, map[string]interface{}{"table": tDisplay, "label": tableLabel(tDisplay), "fields": fields})
		}
		sort.Slice(out, func(i, j int) bool { return out[i]["table"].(string) < out[j]["table"].(string) })
		rec := recommendedDefaults(ds, ot)
		ok(w, r, map[string]interface{}{"datasource": ds, "tables": out, "recommended": rec})
	})
}

// getHiddenFieldsFromCode 从代码中获取指定数据源的隐藏字段映射
func getHiddenFieldsFromCode(ds string) map[string]map[string]bool {
	// 从字段白名单构建隐藏字段映射，所有字段默认 true（隐藏）
	return buildHiddenFieldsFromWhitelist()
}

// buildHiddenFieldsFromWhitelist 读取 schema.AllWhitelist 中的所有字段，按表分组，全部标记为 true
func buildHiddenFieldsFromWhitelist() map[string]map[string]bool {
	out := make(map[string]map[string]bool)
	for k := range schema.AllWhitelist() {
		parts := strings.SplitN(k, ".", 2)
		if len(parts) != 2 {
			continue
		}
		tbl, field := parts[0], parts[1]
		if _, ok := out[tbl]; !ok {
			out[tbl] = make(map[string]bool)
		}
		out[tbl][field] = true
	}
	return out
}

// isFieldHidden 检查字段是否在隐藏列表中
func isFieldHidden(hiddenFields map[string]map[string]bool, table, field string) bool {
	tableFields, ok := hiddenFields[table]
	if !ok {
		return false
	}
	return tableFields[field]
}

func tableLabel(t string) string {
	switch t {
	case "order":
		return "订单主表"
	case "order_detail":
		return "订单详情"
	case "order_cash":
		return "红包订单"
	case "order_voucher":
		return "立减金订单"
	case "order_digit":
		return "直充卡密订单"
	case "plan":
		return "活动"
	case "key_batch":
		return "key批次"
	case "code_batch":
		return "兑换码批次"
	case "voucher":
		return "立减金"
	case "voucher_batch":
		return "立减金批次"
	case "merchant_key_send":
		return "key码API发放记录"
	case "goods_voucher_batch":
		return "立减金批次表"
	case "goods_voucher_subject_config":
		return "立减金主体"
	case "merchant":
		return "客户"
	case "activity":
		return "活动"
	default:
		return t
	}
}

func displayTable(ds, tbl string) string {
	if ds == "ymt" && tbl == "order_info" {
		return "order"
	}
	return tbl
}

func canonicalField(ds, tbl, col string) (string, string) {
	if ds == "ymt" && tbl == "order_info" {
		switch col {
		case "order_no":
			return "order", "order_number"
		case "key_code":
			return "order", "key"
		case "user_id":
			return "order", "creator"
		case "out_order_no":
			return "order", "out_trade_no"
		case "activity_id":
			return "order", "plan_id"
		case "merchant_id":
			return "order", "reseller_id"
		case "goods_id":
			return "order", "product_id"
		case "pay_price":
			return "order", "pay_amount"
		case "key_batch_name":
			return "order", "key_batch_id"
		default:
			return "order", col
		}
	}
	// other tables: canonical equals actual
	return tbl, col
}

type columnMeta struct {
	Name    string
	Comment string
}

func getColumns(db *sql.DB, tbl string) []columnMeta {
	rows, err := db.Query("SELECT COLUMN_NAME, COLUMN_COMMENT FROM information_schema.columns WHERE table_schema = DATABASE() AND table_name = ? ORDER BY ORDINAL_POSITION", tbl)
	if err != nil {
		return []columnMeta{}
	}
	defer rows.Close()
	cols := []columnMeta{}
	for rows.Next() {
		var name, comment string
		if err := rows.Scan(&name, &comment); err == nil {
			cols = append(cols, columnMeta{Name: name, Comment: comment})
		}
	}
	return cols
}

func recommendedDefaults(ds, orderType string) []string {
	base := []string{"order.order_number", "order.creator", "order.out_trade_no", "order.type", "order.status", "order.contract_price", "order.num", "order.pay_amount", "order.create_time"}
	if ds != "ymt" {
		base = []string{"order.order_number", "order.creator", "order.out_trade_no", "order.type", "order.status", "order.contract_price", "order.num", "order.total", "order.pay_amount", "order.create_time"}
	}
	t := orderType
	if t == "2" { // 直充卡密
		if ds == "ymt" {
			base = append(base, "order_digit.order_no", "order_digit.account", "order_digit.success_time")
		} else {
			base = append(base, "plan.title")
		}
	} else if t == "3" { // 立减金
		if ds == "ymt" {
			base = append(base, "order_voucher.channel", "order_voucher.status", "goods_voucher_batch.channel_batch_no")
		} else {
			base = append(base, "order_voucher.channel", "voucher.denomination")
		}
	} else if t == "1" { // 红包
		if ds == "ymt" {
			base = append(base, "order_cash.channel", "order_cash.receive_status", "order_cash.denomination")
		} else {
			base = append(base, "order_cash.channel", "order_cash.receive_status", "order_cash.amount")
		}
	}
	return base
}