package handler

import (
	"encoding/csv"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
)

const exportMaxRows = 5000

func csvEscape(s string) string {
	return strings.ReplaceAll(s, "\r\n", " ")
}

func writeCSVResponse(c *gin.Context, filename string, header []string, rows [][]string) {
	if !strings.HasSuffix(strings.ToLower(filename), ".csv") {
		filename += ".csv"
	}
	// 兼容 Excel 中文：UTF-8 BOM
	c.Header("Content-Type", "text/csv; charset=utf-8")
	c.Header("Content-Disposition", fmt.Sprintf("attachment; filename*=UTF-8''%s", url.PathEscape(filename)))
	c.Status(http.StatusOK)

	if _, err := c.Writer.Write([]byte{0xEF, 0xBB, 0xBF}); err != nil {
		return
	}
	w := csv.NewWriter(c.Writer)
	_ = w.Write(header)
	for _, row := range rows {
		for i := range row {
			row[i] = csvEscape(row[i])
		}
		_ = w.Write(row)
	}
	w.Flush()
}

func formatCSVTime(t time.Time) string {
	if t.IsZero() {
		return ""
	}
	return t.In(time.Local).Format("2006-01-02 15:04:05")
}

func formatCSVTimePtr(t *time.Time) string {
	if t == nil {
		return ""
	}
	return formatCSVTime(*t)
}

func formatUintPtr(v *uint) string {
	if v == nil {
		return ""
	}
	return strconv.FormatUint(uint64(*v), 10)
}

func formatIntPtr(v *int) string {
	if v == nil {
		return ""
	}
	return strconv.Itoa(*v)
}