package medias

import (
	"crypto/md5"
	"encoding/hex"
	"errors"
	"fmt"
	"io"
	"mime/multipart"
	"os"
	"path/filepath"
	"time"

	"github.com/gofiber/fiber/v3"
	log "github.com/sirupsen/logrus"
)

const (
	uploadTempDir    = "./temp/chunks" // 临时分片目录
	uploadStorageDir = "./uploads"     // 最终文件存储目录
)

// @provider
type Controller struct {
	svc *Service
	log *log.Entry `inject:"false"`
}

func (ctl *Controller) Prepare() error {
	ctl.log = log.WithField("module", "medias.Controller")
	return nil
}

// Upload
// @Router			/api/v1/medias/upload [post]
// @Bind req body
// @Bind file file
func (ctl *Controller) Upload(ctx fiber.Ctx, file *multipart.FileHeader, req *UploadReq) (*UploadResp, error) {
	// 使用MD5创建唯一的临时目录
	tempDir := filepath.Join(uploadTempDir, req.FileMD5)
	if err := os.MkdirAll(tempDir, 0o755); err != nil {
		return nil, err
	}

	chunkPath := filepath.Join(tempDir, fmt.Sprintf("chunk_%d", req.ChunkNumber))
	if err := ctx.SaveFile(file, chunkPath); err != nil {
		return nil, err
	}

	// 如果是最后一个分片
	if req.ChunkNumber == req.TotalChunks-1 {
		// 生成唯一的文件存储路径
		ext := filepath.Ext(req.FileName)
		storageDir := filepath.Join(uploadStorageDir, time.Now().Format("2006/01/02"))
		if err := os.MkdirAll(storageDir, 0o755); err != nil {
			os.RemoveAll(tempDir)
			return nil, err
		}

		finalPath := filepath.Join(storageDir, req.FileMD5+ext)

		// 计算所有分片的实际大小总和
		totalSize, err := calculateTotalSize(tempDir, req.TotalChunks)
		if err != nil {
			os.RemoveAll(tempDir)
			return nil, fmt.Errorf("计算文件大小失败: %w", err)
		}

		// 合并文件
		if err := combineChunks(tempDir, finalPath, req.TotalChunks); err != nil {
			os.RemoveAll(tempDir)
			return nil, fmt.Errorf("合并文件失败: %w", err)
		}

		// 验证MD5
		calculatedMD5, err := calculateFileMD5(finalPath)
		if err != nil || calculatedMD5 != req.FileMD5 {
			os.RemoveAll(tempDir)
			os.Remove(finalPath)
			return nil, errors.New("文件MD5验证失败")
		}

		// 清理临时目录
		os.RemoveAll(tempDir)

		return &UploadResp{
			Files: []UploadFile{
				{
					HashID:   calculatedMD5,
					Name:     req.FileName,
					Path:     finalPath,
					Size:     totalSize,
					MimeType: file.Header.Get("Content-Type"),
				},
			},
		}, nil
	}

	return &UploadResp{}, nil
}

// 计算所有分片的实际大小总和
func calculateTotalSize(tempDir string, totalChunks int) (int64, error) {
	var totalSize int64
	for i := 0; i < totalChunks; i++ {
		chunkPath := filepath.Join(tempDir, fmt.Sprintf("chunk_%d", i))
		info, err := os.Stat(chunkPath)
		if err != nil {
			return 0, err
		}
		totalSize += info.Size()
	}
	return totalSize, nil
}

func combineChunks(tempDir, finalPath string, totalChunks int) error {
	finalFile, err := os.Create(finalPath)
	if err != nil {
		return err
	}
	defer finalFile.Close()

	for i := 0; i < totalChunks; i++ {
		chunkPath := fmt.Sprintf("%s/chunk_%d", tempDir, i)
		chunk, err := os.ReadFile(chunkPath)
		if err != nil {
			return err
		}
		if _, err := finalFile.Write(chunk); err != nil {
			return err
		}
	}

	return nil
}

func calculateFileMD5(filePath string) (string, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return "", err
	}
	defer file.Close()

	hash := md5.New()
	if _, err := io.Copy(hash, file); err != nil {
		return "", err
	}

	return hex.EncodeToString(hash.Sum(nil)), nil
}