package handler

import (
	"errors"
	"net/http"
	"net/url"
	"strconv"

	"github.com/gin-gonic/gin"
	"github.com/wmms/wmms/internal/middleware"
	"github.com/wmms/wmms/internal/service"
	"github.com/wmms/wmms/pkg/response"
)

// DownloadMaterialImportTemplate 返回物料导入模板文件。模板随代码生成，
// 不落盘，保证下载到的永远和当前校验规则一致。
func (h *Handler) DownloadMaterialImportTemplate(c *gin.Context) {
	data, err := service.BuildMaterialImportTemplate()
	if err != nil {
		response.InternalError(c, "模板生成失败")
		return
	}
	fileName := url.PathEscape("物料导入模板.xlsx")
	c.Header("Content-Disposition", `attachment; filename="material-import-template.xlsx"; filename*=UTF-8''`+fileName)
	c.Data(http.StatusOK, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", data)
}

// ImportMaterials 接收上传的 xlsx，校验通过即整批入库。
// 校验失败返回 400 且 data 里带逐行错误明细。
func (h *Handler) ImportMaterials(c *gin.Context) {
	orgID, ok := organizationID(c)
	if !ok {
		return
	}

	// 在 multipart 解析前限制读取；文件限额之外仅给表单头部预留少量空间。
	const maxRequestBytes = service.MaterialImportMaxBytes + (64 << 10)
	if c.Request.ContentLength > maxRequestBytes {
		response.BadRequest(c, "文件超过 1MB 上限或表单数据过大")
		return
	}
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, maxRequestBytes)
	defer c.Request.Body.Close()
	defer func() {
		if c.Request.MultipartForm != nil {
			_ = c.Request.MultipartForm.RemoveAll()
		}
	}()

	file, err := c.FormFile("file")
	if err != nil {
		var sizeErr *http.MaxBytesError
		if errors.As(err, &sizeErr) {
			response.BadRequest(c, "文件超过 1MB 上限或表单数据过大")
			return
		}
		response.BadRequest(c, "请选择要导入的 xlsx 文件")
		return
	}
	if file.Size > service.MaterialImportMaxBytes {
		response.BadRequest(c, "文件超过 1MB 上限")
		return
	}

	source, err := file.Open()
	if err != nil {
		response.BadRequest(c, "文件读取失败")
		return
	}
	defer source.Close()

	operator := middleware.GetCurrentUsername(c)
	if operator == "" {
		operator = "系统"
	}

	result, err := h.materialImportSvc.Import(orgID, operator, file.Filename, source)
	if err != nil {
		if errors.Is(err, service.ErrImportTemplateInvalid) || errors.Is(err, service.ErrImportTooManyRows) {
			response.BadRequest(c, err.Error())
			return
		}
		response.InternalError(c, err.Error())
		return
	}
	if result.FailedRows > 0 {
		response.ErrorWithData(c, http.StatusBadRequest,
			"有 "+strconv.Itoa(result.FailedRows)+" 行校验未通过，本次未导入任何数据", result)
		return
	}
	response.Created(c, "成功导入 "+strconv.Itoa(result.SuccessRows)+" 条物料", result)
}