package handlers

import (
	"net/http"
	"os"
	"path/filepath"

	"github.com/gin-gonic/gin"

	"qr-scanner/services"
)

type ExportHandler struct {
	store    *services.TaskStore
	exporter *services.Exporter
}

func NewExportHandler(store *services.TaskStore, exporter *services.Exporter) *ExportHandler {
	return &ExportHandler{store: store, exporter: exporter}
}

func (h *ExportHandler) Download(c *gin.Context) {
	taskID := c.Param("taskID")
	task, ok := h.store.Get(taskID)
	if !ok {
		fail(c, http.StatusNotFound, "任务不存在")
		return
	}
	if task.Status == services.TaskExpired {
		fail(c, http.StatusGone, "任务已过期")
		return
	}

	if task.ExcelPath != "" {
		if _, err := os.Stat(task.ExcelPath); err == nil {
			c.FileAttachment(task.ExcelPath, filepath.Base(task.ExcelPath))
			return
		}
	}

	results := task.Results()
	if len(results) == 0 {
		fail(c, http.StatusConflict, "结果尚未生成")
		return
	}

	out := task.ExportFilename()
	if err := h.exporter.Export(results, out); err != nil {
		fail(c, http.StatusInternalServerError, "生成Excel失败")
		return
	}
	task.ExcelPath = out
	h.store.Put(task)

	c.FileAttachment(out, filepath.Base(out))
}