package handlers

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

	"github.com/gin-gonic/gin"

	"qr-scanner/config"
	"qr-scanner/models"
	"qr-scanner/services"
	"qr-scanner/utils"
)

type UploadHandler struct {
	cfg   config.Config
	store *services.TaskStore
}

func NewUploadHandler(cfg config.Config, store *services.TaskStore) *UploadHandler {
	return &UploadHandler{cfg: cfg, store: store}
}

func (h *UploadHandler) HandleUpload(c *gin.Context) {
	/*
		上传处理策略：
		- 支持多文件上传：图片与 ZIP 可混合（ZIP 会自动解压并提取图片）
		- 自动过滤非图片文件
		- 不对“重名图片”强制覆盖：单独上传的图片会在文件名后追加 _N；ZIP 内则保留相对路径区分
		- 不暴露服务器绝对路径：后续结果只输出压缩包内相对路径/上传文件名
	*/
	form, err := c.MultipartForm()
	if err != nil {
		fail(c, http.StatusBadRequest, "无法解析上传表单")
		return
	}

	files := form.File["files"]
	if len(files) == 0 {
		fail(c, http.StatusBadRequest, "未选择文件")
		return
	}

	taskID := utils.NewTaskID(time.Now())
	taskDir := filepath.Join(h.cfg.TempDir, taskID)
	uploadDir := filepath.Join(taskDir, "upload")
	imageDir := filepath.Join(taskDir, "images")

	if err := os.MkdirAll(uploadDir, 0o755); err != nil {
		fail(c, http.StatusInternalServerError, "创建任务目录失败")
		return
	}
	if err := os.MkdirAll(imageDir, 0o755); err != nil {
		fail(c, http.StatusInternalServerError, "创建任务目录失败")
		return
	}

	allowedExt := map[string]struct{}{
		".png":  {},
		".jpg":  {},
		".jpeg": {},
		".bmp":  {},
	}

	var extracted []utils.ExtractedFile
	used := map[string]int{}

	for _, fh := range files {
		if fh == nil {
			continue
		}
		// 上传大小限制（单文件）：避免单个文件过大导致磁盘/内存压力。
		if h.cfg.MaxUploadMB > 0 && fh.Size > h.cfg.MaxUploadMB*1024*1024 {
			_ = os.RemoveAll(taskDir)
			fail(c, http.StatusBadRequest, "文件大小超出限制")
			return
		}

		name := strings.ReplaceAll(fh.Filename, "\\", "/")
		base := filepath.Base(name)
		ext := strings.ToLower(filepath.Ext(base))

		if ext == ".zip" {
			// ZIP：落盘后再解压。解压过程会做路径穿越防护、总展开大小限制、加密包拒绝等安全校验。
			zipPath := filepath.Join(uploadDir, "upload.zip")
			if err := c.SaveUploadedFile(fh, zipPath); err != nil {
				_ = os.RemoveAll(taskDir)
				fail(c, http.StatusInternalServerError, "保存压缩包失败")
				return
			}

			limits := utils.ZipLimits{
				MaxFiles:      h.cfg.MaxFiles,
				MaxTotalBytes: h.cfg.MaxZipTotalMB * 1024 * 1024,
				MaxFileBytes:  h.cfg.MaxZipFileMB * 1024 * 1024,
			}
			out, err := utils.ExtractZip(zipPath, imageDir, allowedExt, limits)
			if err != nil {
				_ = os.RemoveAll(taskDir)
				fail(c, http.StatusBadRequest, err.Error())
				return
			}
			extracted = append(extracted, out...)
			continue
		}

		if _, ok := allowedExt[ext]; !ok {
			// 非图片：直接忽略（符合 PRD 的“自动过滤非图片文件”规则）。
			continue
		}

		rel := base
		if n := used[rel]; n > 0 {
			// 同名冲突：仅针对“直接上传的图片”，通过追加 _N 避免覆盖。
			rel = strings.TrimSuffix(base, ext) + "_" + strconv.Itoa(n) + ext
		}
		used[base]++

		dst := filepath.Join(imageDir, rel)
		if err := c.SaveUploadedFile(fh, dst); err != nil {
			_ = os.RemoveAll(taskDir)
			fail(c, http.StatusInternalServerError, "保存图片失败")
			return
		}
		extracted = append(extracted, utils.ExtractedFile{RelPath: rel, AbsPath: dst})
	}

	if len(extracted) == 0 {
		_ = os.RemoveAll(taskDir)
		fail(c, http.StatusBadRequest, "未发现可识别的图片文件")
		return
	}
	if h.cfg.MaxFiles > 0 && len(extracted) > h.cfg.MaxFiles {
		_ = os.RemoveAll(taskDir)
		fail(c, http.StatusBadRequest, "文件数量超出限制")
		return
	}

	taskFiles := make([]services.TaskFile, 0, len(extracted))
	for i, ef := range extracted {
		taskFiles = append(taskFiles, services.TaskFile{
			Index:   i + 1,
			RelPath: filepath.ToSlash(ef.RelPath),
			AbsPath: ef.AbsPath,
		})
	}

	task := &services.Task{
		ID:        taskID,
		TempDir:   taskDir,
		CreatedAt: time.Now(),
		UpdatedAt: time.Now(),
		Status:    services.TaskUploaded,
		Files:     taskFiles,
	}
	h.store.Put(task)

	respondOK(c, models.UploadResponse{TaskID: taskID, TotalFiles: len(taskFiles)})
}