package handler

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

	"bj_power_wms/ent"
	"bj_power_wms/ent/attachment"
	"bj_power_wms/internal/svc"

	"github.com/google/uuid"
)

const (
	// maxAttachmentSize 单文件上限 20MB（图纸 PDF/检验报告足够；超限直接拒绝，避免拖垮服务）
	maxAttachmentSize = 20 << 20
	// uploadRoot 附件磁盘根目录（相对服务运行目录）
	uploadRoot = "uploads"
)

// allowedAttachmentExt 允许的附件扩展名白名单（图纸/报告/图片/表格）。
// 白名单而非黑名单：避免上传可执行文件。
var allowedAttachmentExt = map[string]bool{
	".pdf": true, ".png": true, ".jpg": true, ".jpeg": true, ".gif": true,
	".xlsx": true, ".xls": true, ".doc": true, ".docx": true,
	".dwg": true, ".dxf": true, ".zip": true, ".txt": true, ".csv": true,
}

// uploadAttachmentHandler 上传附件（multipart/form-data）
// 表单字段：bizType、bizId、file
// 落盘：uploads/<uuid><ext>（纯 ASCII 名，规避中文 URL 编码问题），原始文件名存库。
func uploadAttachmentHandler(ctx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if err := r.ParseMultipartForm(maxAttachmentSize); err != nil {
			fail(w, http.StatusBadRequest, "解析上传表单失败（单文件不超过20MB）: "+err.Error())
			return
		}
		bizType := strings.TrimSpace(r.FormValue("bizType"))
		bizId := strings.TrimSpace(r.FormValue("bizId"))
		if bizType == "" || bizId == "" {
			fail(w, http.StatusBadRequest, "bizType 与 bizId 必填")
			return
		}
		file, header, err := r.FormFile("file")
		if err != nil {
			fail(w, http.StatusBadRequest, "未取到上传文件: "+err.Error())
			return
		}
		defer file.Close()

		if header.Size > maxAttachmentSize {
			fail(w, http.StatusBadRequest, "文件超过 20MB 上限，请压缩后重传")
			return
		}
		ext := strings.ToLower(filepath.Ext(header.Filename))
		if ext == "" || !allowedAttachmentExt[ext] {
			fail(w, http.StatusBadRequest, "不支持的文件类型（仅支持 PDF/图片/Office/图纸/压缩包）")
			return
		}

		if err := os.MkdirAll(uploadRoot, 0o755); err != nil {
			fail(w, http.StatusInternalServerError, "创建附件目录失败: "+err.Error())
			return
		}
		storedName := uuid.NewString() + ext
		dst := filepath.Join(uploadRoot, storedName)
		out, err := os.Create(dst)
		if err != nil {
			fail(w, http.StatusInternalServerError, "写入附件失败: "+err.Error())
			return
		}
		defer out.Close()
		size, err := io.Copy(out, file)
		if err != nil {
			_ = os.Remove(dst)
			fail(w, http.StatusInternalServerError, "保存附件失败: "+err.Error())
			return
		}

		rec, err := ctx.EntClient.Attachment.Create().
			SetBizType(bizType).
			SetBizID(bizId).
			SetFileName(header.Filename).
			SetFilePath(storedName).
			SetFileSize(size).
			SetNillableMimeType(strPtr(header.Header.Get("Content-Type"))).
			SetNillableUploadedBy(strPtr(r.Header.Get("X-Username"))).
			Save(ctx0())
		if err != nil {
			_ = os.Remove(dst)
			fail(w, http.StatusInternalServerError, "登记附件失败: "+err.Error())
			return
		}

		ctx.EventLog.Write(ctx0(), "attachment.upload", r.Header.Get("X-Username"), bizType, bizId,
			"上传附件 "+header.Filename, map[string]any{"fileSize": size})
		ok(w, attachmentView(rec))
	}
}

// attachmentView 附件返回视图：附带可直接预览的 URL
type attachmentViewRow struct {
	ID         int64  `json:"id"`
	BizType    string `json:"bizType"`
	BizID      string `json:"bizId"`
	FileName   string `json:"fileName"`
	FileSize   int64  `json:"fileSize"`
	MimeType   string `json:"mimeType"`
	UploadedBy string `json:"uploadedBy"`
	CreatedAt  int64  `json:"createdAt"`
	URL        string `json:"url"`
}

func attachmentView(rec *ent.Attachment) *attachmentViewRow {
	return &attachmentViewRow{
		ID:         int64(rec.ID),
		BizType:    rec.BizType,
		BizID:      rec.BizID,
		FileName:   rec.FileName,
		FileSize:   rec.FileSize,
		MimeType:   rec.MimeType,
		UploadedBy: rec.UploadedBy,
		CreatedAt:  rec.CreatedAt,
		URL:        "/uploads/" + rec.FilePath,
	}
}

// listAttachmentsHandler 查询某业务对象的附件列表
// GET /api/attachments?bizType=&bizId=
func listAttachmentsHandler(ctx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		bizType := r.URL.Query().Get("bizType")
		bizId := r.URL.Query().Get("bizId")
		if bizType == "" || bizId == "" {
			fail(w, http.StatusBadRequest, "bizType 与 bizId 必填")
			return
		}
		list, err := ctx.EntClient.Attachment.Query().
			Where(attachment.BizTypeEQ(bizType), attachment.BizIDEQ(bizId)).
			Order(ent.Desc("created_at"), ent.Desc("id")).
			All(ctx0())
		if err != nil {
			fail(w, http.StatusInternalServerError, err.Error())
			return
		}
		rows := make([]*attachmentViewRow, 0, len(list))
		for _, rec := range list {
			rows = append(rows, attachmentView(rec))
		}
		ok(w, map[string]any{"list": rows, "total": len(rows)})
	}
}

// deleteAttachmentHandler 删除附件（同时删除磁盘文件）
// POST /api/attachments/delete  body: { id }
func deleteAttachmentHandler(ctx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			ID int64 `json:"id"`
		}
		if err := parseJSON(r, &req); err != nil || req.ID <= 0 {
			fail(w, http.StatusBadRequest, "参数错误：id 必填")
			return
		}
		rec, err := ctx.EntClient.Attachment.Get(ctx0(), int(req.ID))
		if err != nil {
			fail(w, http.StatusNotFound, "附件不存在")
			return
		}
		if err := ctx.EntClient.Attachment.DeleteOneID(int(req.ID)).Exec(ctx0()); err != nil {
			fail(w, http.StatusInternalServerError, "删除附件失败: "+err.Error())
			return
		}
		_ = os.Remove(filepath.Join(uploadRoot, filepath.Base(rec.FilePath)))
		ctx.EventLog.Write(ctx0(), "attachment.delete", r.Header.Get("X-Username"), rec.BizType, rec.BizID,
			"删除附件 "+rec.FileName, nil)
		ok(w, map[string]any{"id": req.ID})
	}
}

// serveUploadFileHandler 附件静态文件服务（PDF 预览/图片查看），免鉴权。
// GET /uploads/:name —— 仅允许扁平文件名（uuid+ext），显式阻断目录穿越。
func serveUploadFileHandler() http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		name := filepath.Base(r.URL.Path) // 只取最后一段，消灭 ../ 穿越
		if name == "" || name == "." || name == "/" {
			http.NotFound(w, r)
			return
		}
		p := filepath.Join(uploadRoot, name)
		if _, err := os.Stat(p); err != nil {
			http.NotFound(w, r)
			return
		}
		http.ServeFile(w, r, p)
	}
}