package ws

import (
	"crypto/rand"
	"encoding/base64"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"

	"sectorinf.com/emilis/fupie/ws/route"
)

var (
	base64Stripper = strings.NewReplacer("/", "", "+", "", "=", "")
)

func Upload(rootDir, redirect string, maxBytes int64) (route.HandlerFunc, error) {
	stat, err := os.Stat(rootDir)
	if err != nil {
		return nil, fmt.Errorf("stat [%s]: %w", rootDir, err)
	}
	if !stat.IsDir() {
		return nil, fmt.Errorf("root path [%s] is not a directory", rootDir)
	}
	rootDir, err = filepath.Abs(rootDir)
	if err != nil {
		return nil, fmt.Errorf("abs filepath [%s]: %w", rootDir, err)
	}
	redirect = strings.TrimRight(redirect, "/")
	return func(ctx route.Context) {
		if err := ctx.Request.ParseMultipartForm(maxBytes); err != nil {
			ctx.Status(http.StatusBadRequest)
			return
		}
		uploads := ctx.Request.MultipartForm.File["upload"]
		if len(uploads) != 1 {
			ctx.Status(http.StatusBadRequest)
			return
		}
		header := uploads[0]
		file, err := header.Open()
		if err != nil {
			ctx.InternalServerErrorf("header.Open: %s", err.Error())
			return
		}
		newFilename := rename(header.Filename)
		path := filepath.Join(rootDir, newFilename)
		fsFile, err := os.Create(path)
		if err != nil {
			ctx.InternalServerErrorf("creating file at [%s]: %s", path, err.Error())
			return
		}

		if _, err := io.CopyBuffer(fsFile, file, nil); err != nil {
			ctx.InternalServerErrorf("writing file at [%s]: %s", path, err.Error())
			return
		}
		fsFile.Close()
		ctx.SeeOther(fmt.Sprintf("%s/%s", redirect, newFilename))
	}, nil
}

func rename(name string) string {
	return fmt.Sprintf("%s_%s", randName(4), name)
}

func randName(bytes int) string {
	buffer := make([]byte, bytes)
	_, err := rand.Read(buffer)
	if err != nil {
		panic(err)
	}

	return base64Stripper.Replace(base64.StdEncoding.EncodeToString(buffer))
}