some work on platform file

platform/file.go

@@ -1,19 +1,63 @@
 package platform
 
-import "github.com/FooSoft/lazarus/formats/mpq"
+import (
+	"errors"
+	"path/filepath"
+
+	"github.com/FooSoft/lazarus/formats/mpq"
+)
 
 var fileState struct {
 	mountPoints map[string]*mpq.Archive
+	mountPaths  map[string]*mpq.Archive
 }
 
-type File struct {
-}
+type File struct{}
 
 func FileMountArchive(mountPath, archivePath string) error {
+	archive, err := mpq.NewFromFile(archivePath)
+	if err != nil {
+		return err
+	}
+
+	if fileState.mountPoints == nil {
+		fileState.mountPoints = make(map[string]*mpq.Archive)
+	}
+
+	var count int
+	for _, path := range archive.GetPaths() {
+		resourcePath := filepath.Join(mountPath, path)
+		if _, ok := fileState.mountPoints[resourcePath]; !ok {
+			fileState.mountPoints[resourcePath] = archive
+			count++
+		}
+	}
+
+	if count == 0 {
+		archive.Close()
+		return errors.New("file archive could not be mounted")
+	}
+
 	return nil
 }
 
 func FileUnmountArchive(mountPath string) error {
+	archive, ok := fileState.mountPoints[mountPath]
+	if !ok {
+		return errors.New("file archive is nout mounted")
+	}
+
+	var paths []string
+	for p, a := range fileState.mountPaths {
+		if archive == a {
+			paths = append(paths, p)
+		}
+	}
+
+	for _, p := range paths {
+		delete(fileState.mountPaths, p)
+	}
+
 	return nil
 }