// Package upload 提供平台总后台的受控文件上传服务。
package upload

import (
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"git.apinb.com/bsm-sdk/core/errcode"
	"git.apinb.com/bsm-sdk/core/infra"
	"git.apinb.com/heqiapp/platforms/backend/api/internal/models"
	"github.com/gin-gonic/gin"
)

const maxUploadSize int64 = 10 << 20

var allowedExtensions = map[string]struct{}{
	".jpg": {}, ".jpeg": {}, ".png": {}, ".webp": {}, ".pdf": {},
}

// UploadFileReply 是文件上传完成后返回的受控资源标识。
type UploadFileReply struct {
	URI          string `json:"uri"`           // 资源访问标识，后续可由对象存储适配层解析
	OriginalName string `json:"original_name"` // 原始文件名，仅用于展示
	ContentType  string `json:"content_type"`  // 客户端声明的媒体类型
	Size         int64  `json:"size"`          // 文件字节数
}

// UploadFile 将允许类型的文件保存至本地 Mock 存储，不直接暴露绝对磁盘路径。
func UploadFile(ctx *gin.Context) {
	ctx.Request.Body = http.MaxBytesReader(ctx.Writer, ctx.Request.Body, maxUploadSize)
	fileHeader, err := ctx.FormFile("file")
	if err != nil || fileHeader == nil || fileHeader.Size <= 0 || fileHeader.Size > maxUploadSize {
		infra.Response.Error(ctx, errcode.ErrInvalidArgument)
		return
	}

	extension := strings.ToLower(filepath.Ext(fileHeader.Filename))
	if _, allowed := allowedExtensions[extension]; !allowed {
		infra.Response.Error(ctx, errcode.ErrInvalidArgument)
		return
	}

	file, err := fileHeader.Open()
	if err != nil {
		infra.Response.Error(ctx, err)
		return
	}
	defer file.Close()

	datePath := time.Now().Format("2006/01/02")
	filename := models.NewIdentity() + extension
	directory := filepath.Join(uploadRoot(), filepath.FromSlash(datePath))
	if err := os.MkdirAll(directory, 0o750); err != nil {
		infra.Response.Error(ctx, err)
		return
	}

	target, err := os.OpenFile(filepath.Join(directory, filename), os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o640)
	if err != nil {
		infra.Response.Error(ctx, err)
		return
	}
	defer target.Close()
	if _, err := io.Copy(target, file); err != nil {
		infra.Response.Error(ctx, err)
		return
	}

	infra.Response.Success(ctx, UploadFileReply{
		URI:          "/uploads/" + datePath + "/" + filename,
		OriginalName: fileHeader.Filename,
		ContentType:  fileHeader.Header.Get("Content-Type"),
		Size:         fileHeader.Size,
	})
}

// uploadRoot 返回本地 Mock 存储根目录；生产环境可通过环境变量映射到受控挂载目录。
func uploadRoot() string {
	if directory := strings.TrimSpace(os.Getenv("HEQI_UPLOAD_DIR")); directory != "" {
		return directory
	}
	return filepath.Join("runtime", "uploads")
}