server: implement local file management

server/api/file.go

@@ -0,0 +1,156 @@
+package api
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/render"
+	"github.com/google/uuid"
+)
+
+func initFileStore() FileStore {
+	val, ok := os.LookupEnv("FILE_BACKEND")
+	if !ok {
+		slog.Error("FILE_BACKEND environment variable not set")
+		os.Exit(1)
+	}
+	switch FileBackend(val) {
+	case FileBackendLocal:
+		localFilePath, ok := os.LookupEnv("LOCAL_FILEPATH")
+		if !ok {
+			slog.Error("LOCAL_FILEPATH environment variable not set")
+			os.Exit(1)
+		}
+		return &LocalFileStore{BaseDir: localFilePath}
+	}
+	slog.Error("unsupported FILE_BACKEND", "value", val)
+	os.Exit(1)
+	return nil
+}
+
+type File struct {
+	ID      uuid.UUID
+	Name    string
+	Created time.Time
+	Backend FileBackend
+	Path    string
+}
+
+type FileBackend string
+
+const (
+	FileBackendLocal FileBackend = "local"
+	FileBackendS3    FileBackend = "s3"
+)
+
+var Store FileStore
+
+type FileStore interface {
+	Save(name string, r io.Reader) (*File, error)
+	URL(file *File) (string, error)
+}
+
+type LocalFileStore struct {
+	BaseDir string
+}
+
+func (s *LocalFileStore) Save(name string, r io.Reader) (*File, error) {
+	id := uuid.New()
+	path := filepath.Join(s.BaseDir, id.String())
+
+	f, err := os.Create(path)
+	if err != nil {
+		return nil, fmt.Errorf("file(local): failed to create file: %w", err)
+	}
+	defer f.Close()
+
+	if _, err := io.Copy(f, r); err != nil {
+		os.Remove(path)
+		return nil, fmt.Errorf("file(local): failed to write file: %w", err)
+	}
+
+	return &File{
+		ID:      id,
+		Name:    name,
+		Created: time.Now(),
+		Backend: FileBackendLocal,
+		Path:    path,
+	}, nil
+}
+
+func (s *LocalFileStore) URL(file *File) (string, error) {
+	return "/files/" + file.ID.String(), nil
+}
+
+func ServeFile(w http.ResponseWriter, r *http.Request) {
+	slog.Debug("file: entering ServeFile handler")
+
+	fileID := chi.URLParam(r, "fileID")
+	parsed, err := uuid.Parse(fileID)
+	if err != nil {
+		render.Render(w, r, ErrInvalidRequest(err))
+		return
+	}
+
+	file, err := dbGetFile(parsed.String())
+	if err != nil {
+		if errors.Is(err, ErrFileNotFound) {
+			render.Render(w, r, ErrNotFound)
+		} else {
+			slog.Error("file: failed to fetch file", "fileid", parsed.String(), "error", err)
+			render.Render(w, r, ErrInternal(err))
+		}
+		return
+	}
+
+	f, err := os.Open(file.Path)
+	if err != nil {
+		slog.Error("file: failed to open file", "fileid", file.ID, "error", err)
+		render.Render(w, r, ErrInternal(err))
+		return
+	}
+	defer f.Close()
+
+	http.ServeContent(w, r, file.Name, file.Created, f)
+}
+
+// UploadFile is a temporary handler for testing file uploads.
+/*
+func UploadFile(w http.ResponseWriter, r *http.Request) {
+	slog.Debug("file: entering UploadFile handler")
+
+	if err := r.ParseMultipartForm(32 << 20); err != nil {
+		render.Render(w, r, ErrInvalidRequest(err))
+		return
+	}
+
+	f, header, err := r.FormFile("file")
+	if err != nil {
+		render.Render(w, r, ErrInvalidRequest(err))
+		return
+	}
+	defer f.Close()
+
+	file, err := Store.Save(header.Filename, f)
+	if err != nil {
+		slog.Error("file: failed to save file", "error", err)
+		render.Render(w, r, ErrInternal(err))
+		return
+	}
+
+	if err := dbAddFile(file); err != nil {
+		render.Render(w, r, ErrInternal(err))
+		return
+	}
+
+	slog.Debug("file: uploaded file", "fileid", file.ID, "filename", file.Name)
+	render.Render(w, r, NewFilePayloadResponse(file))
+}
+*/