book-comic-library/backend/cmd/webui/handlers/libraries.go

package handlers

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

	"github.com/gin-gonic/gin"
	"github.com/jackc/pgx/v5"

	"booklib/internal/bookfile"
	"booklib/internal/media"
	"booklib/internal/ports"
	"booklib/internal/store"
)

// resolveLibRoot: root_path 必须绝对且落在 BooksDir 内(spec §7 前缀校验)
func (h *H) libRoot(c *gin.Context, lib store.Library) (string, bool) {
	root := filepath.Clean(lib.RootPath)
	books := filepath.Clean(h.cfg.BooksDir)
	if !filepath.IsAbs(root) || !bookfile.Contains(books, root) {
		err(c, http.StatusForbidden, "forbidden", "library root outside books dir")
		return "", false
	}
	if e := os.MkdirAll(root, 0o755); e != nil { // 注册库时目录可能尚未落盘,自愈
		err(c, http.StatusInternalServerError, "internal", "library root")
		return "", false
	}
	return root, true
}

// getLib 查库行,404/503/500 已回复(原 getLibrary/getLibRow 合一,Task 25)
func (h *H) getLib(c *gin.Context, id int64) (store.Library, bool) {
	l, e := h.libs.GetLibrary(c, id)
	if e != nil {
		if errors.Is(e, pgx.ErrNoRows) {
			err(c, http.StatusNotFound, "not_found", "no such library")
			return store.Library{}, false
		}
		dbErr(c, e)
		return store.Library{}, false
	}
	return l, true
}

func (h *H) ListLibraries(c *gin.Context) {
	libs, e := h.libs.ListLibraries(c)
	if e != nil {
		dbErr(c, e)
		return
	}
	out := make([]gin.H, 0, len(libs))
	for _, l := range libs {
		out = append(out, gin.H{"id": l.ID, "name": l.Name, "root_path": l.RootPath,
			"created_at": l.CreatedAt.Format(time.RFC3339)})
	}
	c.JSON(http.StatusOK, out)
}

// CreateLibrary: root_path 由服务端生成(BooksDir/SafeName(name)),不接受客户端指定
func (h *H) CreateLibrary(c *gin.Context) {
	var req struct {
		Name string `json:"name"`
	}
	if c.ShouldBindJSON(&req) != nil {
		err(c, http.StatusBadRequest, "bad_request", "name required")
		return
	}
	safe := bookfile.SafeName(req.Name)
	if safe == "" || safe == ".." {
		err(c, http.StatusBadRequest, "bad_request", "bad name")
		return
	}
	// B8: reject reserved names that conflict with system directories.
	if media.IsReservedName(safe) {
		err(c, http.StatusBadRequest, "bad_request", "reserved_name")
		return
	}
	root := filepath.Join(filepath.Clean(h.cfg.BooksDir), safe)
	id, e := h.libs.CreateLibrary(c, req.Name, root)
	if e != nil {
		if ports.IsUniqueViolation(e) {
			err(c, http.StatusConflict, "exists", "name taken")
			return
		}
		dbErr(c, e)
		return
	}
	c.JSON(http.StatusCreated, gin.H{"id": id, "name": req.Name, "root_path": root})
}

func (h *H) ScanLibrary(c *gin.Context) {
	id, ok := idParam(c)
	if !ok {
		return
	}
	lib, ok := h.getLib(c, id)
	if !ok {
		return
	}
	if _, ok := h.libRoot(c, lib); !ok {
		return
	}
	go h.sc.ScanLibraryByID(context.WithoutCancel(c), lib.ID)
	c.JSON(http.StatusAccepted, gin.H{"accepted": true})
}

func (h *H) Upload(c *gin.Context) {
	id, ok := idParam(c)
	if !ok {
		return
	}
	lib, ok := h.getLib(c, id)
	if !ok {
		return
	}
	root, ok := h.libRoot(c, lib)
	if !ok {
		return
	}
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, h.cfg.UploadMaxMB<<20)
	fh, e := c.FormFile("file")
	if e != nil {
		var mbe *http.MaxBytesError
		if errors.As(e, &mbe) {
			err(c, http.StatusRequestEntityTooLarge, "too_large", "file exceeds upload limit of "+strconv.FormatInt(h.cfg.UploadMaxMB, 10)+"MB")
			return
		}
		err(c, http.StatusBadRequest, "bad_request", "multipart field 'file' required")
		return
	}
	name := bookfile.SafeName(fh.Filename)
	if bookfile.FormatFromExt(name) == "" {
		err(c, http.StatusBadRequest, "bad_format", "extension must be cbz/pdf/epub/txt/md")
		return
	}
	// B12: retry on O_EXCL collision — concurrent uploads with the same name
	// can both get the same candidate from UniquePath (stat-then-create race).
	var dst, tmp string
	var out *os.File
	for attempt := 0; attempt < 5; attempt++ {
		var e error
		dst, e = h.up.UniquePath(root, name)
		if e != nil {
			err(c, http.StatusForbidden, "forbidden", e.Error())
			return
		}
		tmp = dst + ".upload-" + strconv.FormatInt(time.Now().UnixNano(), 36)
		out, e = os.OpenFile(tmp, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o644)
		if e == nil {
			break
		}
		if !os.IsExist(e) {
			err(c, http.StatusInternalServerError, "internal", "create tmp")
			return
		}
		// O_EXCL collision — retry with fresh UniquePath.
	}
	if out == nil {
		err(c, http.StatusConflict, "conflict", "too many concurrent uploads with same name")
		return
	}
	src, e := fh.Open()
	if e != nil {
		out.Close()
		os.Remove(tmp)
		err(c, http.StatusInternalServerError, "internal", "open upload")
		return
	}
	defer src.Close()
	// B6: only MaxBytesError returns 413; other io.Copy failures (disk full,
	// connection drop) return 500.
	if _, e := io.Copy(out, src); e != nil {
		out.Close()
		os.Remove(tmp)
		var mbe *http.MaxBytesError
		if errors.As(e, &mbe) {
			err(c, http.StatusRequestEntityTooLarge, "too_large", "file exceeds upload limit")
			return
		}
		err(c, http.StatusInternalServerError, "internal", "upload failed")
		return
	}
	out.Close()
	if e := os.Rename(tmp, dst); e != nil { // 原子落盘,scanner 自动收编
		os.Remove(tmp)
		err(c, http.StatusInternalServerError, "internal", "rename")
		return
	}
	c.JSON(http.StatusAccepted, gin.H{"accepted": true, "path": strings.TrimPrefix(dst, root+string(os.PathSeparator))})
}