package ai

import (
	"context"
	"encoding/csv"
	"fmt"
	"net/http"
	"time"

	"github.com/youruser/base/internal/svc"
	"github.com/youruser/base/internal/types"
	"github.com/youruser/base/model"

	"github.com/zeromicro/go-zero/core/logx"
)

type AiUsageExportLogic struct {
	logx.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewAiUsageExportLogic(ctx context.Context, svcCtx *svc.ServiceContext) *AiUsageExportLogic {
	return &AiUsageExportLogic{
		Logger: logx.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *AiUsageExportLogic) AiUsageExport(req *types.AIUsageRecordListRequest, w http.ResponseWriter) error {
	// Get current user from context
	userId := req.UserId
	if userId == 0 {
		if uid, ok := l.ctx.Value("userId").(int64); ok {
			userId = uid
		} else if uidJson, ok2 := l.ctx.Value("userId").(float64); ok2 {
			userId = int64(uidJson)
		}
	}

	// Fetch all records (large page size for export)
	records, _, err := model.AIUsageRecordFindList(l.ctx, l.svcCtx.DB, userId, req.ModelId, req.Status, 1, 10000)
	if err != nil {
		return err
	}

	// Build lookup caches
	userMap := make(map[int64]string)
	providerMap := make(map[int64]string)
	for _, r := range records {
		if _, ok := userMap[r.UserId]; !ok {
			user, err := model.FindOne(l.ctx, l.svcCtx.DB, r.UserId)
			if err == nil {
				userMap[r.UserId] = user.Username
			}
		}
		if _, ok := providerMap[r.ProviderId]; !ok {
			p, err := model.AIProviderFindOne(l.ctx, l.svcCtx.DB, r.ProviderId)
			if err == nil {
				providerMap[r.ProviderId] = p.DisplayName
			}
		}
	}

	// Write CSV response
	filename := fmt.Sprintf("ai-usage-%s.csv", time.Now().Format("20060102"))
	w.Header().Set("Content-Type", "text/csv; charset=utf-8")
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
	// BOM for Excel UTF-8 support
	w.Write([]byte{0xEF, 0xBB, 0xBF})

	writer := csv.NewWriter(w)
	defer writer.Flush()

	// Header row
	writer.Write([]string{"时间", "用户", "平台", "模型", "输入Tokens", "输出Tokens", "费用(¥)", "延迟(ms)", "状态", "错误信息"})

	for _, r := range records {
		writer.Write([]string{
			r.CreatedAt.Format("2006-01-02 15:04:05"),
			userMap[r.UserId],
			providerMap[r.ProviderId],
			r.ModelId,
			fmt.Sprintf("%d", r.InputTokens),
			fmt.Sprintf("%d", r.OutputTokens),
			fmt.Sprintf("%.4f", r.Cost),
			fmt.Sprintf("%d", r.LatencyMs),
			r.Status,
			r.ErrorMessage,
		})
	}

	return nil
}