package request

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"io"
	"lone-services/bff/internal/response"
	"lone-services/pkg/oss"
	"net/http"
	"path/filepath"
	"strings"
)

const (
	ossUploadAPIPath = "/api/v3/chore/oss/upload"
	formFileField    = "file"
	maxUploadMemory  = oss.MaxUploadBytes
)

func FormUploadMiddleware(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost || r.URL.Path != ossUploadAPIPath {
			next(w, r)
			return
		}

		ct := r.Header.Get("Content-Type")
		ctrl := &response.BaseController{}
		if !strings.HasPrefix(strings.ToLower(ct), "multipart/form-data") {
			ctrl.Error(w, response.Define(response.ErrorMissingParams, "请使用 multipart/form-data 上传，字段名为 file"))
			return
		}

		if err := r.ParseMultipartForm(int64(maxUploadMemory)); err != nil {
			ctrl.Error(w, response.Define(response.ErrorMissingParams, "解析上传文件失败"))
			return
		}
		file, header, err := r.FormFile(formFileField)
		if err != nil {
			ctrl.Error(w, response.Define(response.ErrorMissingParams, "请上传文件，字段名为 file"))
			return
		}
		defer file.Close()

		content, err := io.ReadAll(io.LimitReader(file, int64(maxUploadMemory)+1))
		if err != nil || len(content) == 0 {
			ctrl.Error(w, response.Define(response.ErrorMissingParams, "文件内容不能为空"))
			return
		}
		if len(content) > maxUploadMemory {
			ctrl.Error(w, response.Define(response.ErrorMissingParams, "文件过大，最大 128MB"))
			return
		}

		filename := filepath.Base(header.Filename)
		if filename == "." || filename == "" {
			filename = "file"
		}

		payload, err := json.Marshal(map[string]string{
			"filename": filename,
			"content":  base64.StdEncoding.EncodeToString(content),
		})
		if err != nil {
			ctrl.Fail(w)
			return
		}

		r.Body = io.NopCloser(bytes.NewReader(payload))
		r.ContentLength = int64(len(payload))
		r.Header.Set("Content-Type", "application/json")
		next(w, r)
	}
}