From 055c815406da0ebb010301eb39b3cd9b3622b4e9 Mon Sep 17 00:00:00 2001
From: Alex Yatskov <alex@foosoft.net>
Date: Tue, 8 Jan 2019 19:15:23 -0800
Subject: [PATCH] add explicit platform initialization and shutdown

---
 platform/file.go        | 10 +++++++
 platform/platform.go    | 60 ++++++++++++++++++++++++++++-------------
 platform/window.go      |  2 --
 streaming/bytewriter.go | 57 +++++++++++++++++++++++++++++++++++++++
 tools/viewer/viewer.go  |  3 +++
 5 files changed, 112 insertions(+), 20 deletions(-)
 create mode 100644 streaming/bytewriter.go

diff --git a/platform/file.go b/platform/file.go
index da34b48..0dfc0c4 100644
--- a/platform/file.go
+++ b/platform/file.go
@@ -17,6 +17,16 @@ func FileUnmountArchive(mountPath string) error {
 	return nil
 }
 
+func FileUnmountAll() error {
+	for _, archive := range fileState.mountPoints {
+		if err := archive.Close(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 func FileOpen(path string) (*File, error) {
 	return nil, nil
 }
diff --git a/platform/platform.go b/platform/platform.go
index 36b2ec7..9e03f04 100644
--- a/platform/platform.go
+++ b/platform/platform.go
@@ -1,17 +1,57 @@
 package platform
 
 import (
+	"errors"
 	"log"
 	"runtime"
 
 	"github.com/veandco/go-sdl2/sdl"
 )
 
-var platfromState struct {
-	sdlIsInit bool
+var (
+	ErrPlatformNotInit = errors.New("platform is not initialized")
+)
+
+var platformState struct {
+	isInit bool
+}
+
+func Initialize() error {
+	log.Println("platform init")
+
+	if platformState.isInit {
+		return nil
+	}
+
+	runtime.LockOSThread()
+
+	if err := sdl.Init(sdl.INIT_VIDEO); err != nil {
+		return err
+	}
+
+	platformState.isInit = true
+	return nil
+}
+
+func Shutdown() error {
+	log.Println("platform shutdown")
+
+	if !platformState.isInit {
+		return nil
+	}
+
+	if err := FileUnmountAll(); err != nil {
+		return err
+	}
+
+	return nil
 }
 
 func Advance() (bool, error) {
+	if !platformState.isInit {
+		return false, ErrPlatformNotInit
+	}
+
 	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
 		switch event.(type) {
 		case *sdl.QuitEvent:
@@ -30,19 +70,3 @@ func Advance() (bool, error) {
 
 	return run, err
 }
-
-func platformInit() error {
-	if platfromState.sdlIsInit {
-		return nil
-	}
-
-	runtime.LockOSThread()
-
-	log.Println("sdl init")
-	if err := sdl.Init(sdl.INIT_VIDEO); err != nil {
-		return err
-	}
-
-	platfromState.sdlIsInit = true
-	return nil
-}
diff --git a/platform/window.go b/platform/window.go
index 9d26b4a..4d3e1b7 100644
--- a/platform/window.go
+++ b/platform/window.go
@@ -43,8 +43,6 @@ func WindowCreate(title string, size math.Vec2i, scene Scene) error {
 		return ErrWindowExists
 	}
 
-	platformInit()
-
 	var err error
 	log.Println("window create")
 	if windowState.sdlWindow, err = sdl.CreateWindow(title, sdl.WINDOWPOS_CENTERED, sdl.WINDOWPOS_CENTERED, int32(size.X), int32(size.Y), sdl.WINDOW_OPENGL); err != nil {
diff --git a/streaming/bytewriter.go b/streaming/bytewriter.go
new file mode 100644
index 0000000..1ef4da2
--- /dev/null
+++ b/streaming/bytewriter.go
@@ -0,0 +1,57 @@
+package streaming
+
+import (
+	"errors"
+	"io"
+)
+
+type Writer interface {
+	io.WriteSeeker
+}
+
+type writer struct {
+	data   []byte
+	offset int
+}
+
+func NewWriter(data []byte) Writer {
+	return &writer{data, 0}
+}
+
+func (w *writer) Write(data []byte) (int, error) {
+	length := len(data)
+	if w.offset+length > len(w.data) {
+		length = len(w.data) - w.offset
+	}
+
+	if length == 0 {
+		return 0, errors.New("cannot write past end of buffer")
+	}
+
+	copy(w.data[w.offset:], data[:length])
+	w.offset += length
+
+	return length, nil
+}
+
+func (w *writer) Seek(offset int64, whence int) (int64, error) {
+	result := w.offset
+	switch whence {
+	case io.SeekStart:
+		result = int(offset)
+	case io.SeekCurrent:
+		result = w.offset + int(offset)
+	case io.SeekEnd:
+		result = len(w.data) - int(offset)
+	}
+
+	if result < 0 {
+		return int64(w.offset), errors.New("cannot seek before beginning of buffer")
+	}
+	if result >= len(w.data) {
+		return int64(w.offset), errors.New("cannot seek past end of buffer")
+	}
+
+	w.offset = result
+	return int64(w.offset), nil
+}
diff --git a/tools/viewer/viewer.go b/tools/viewer/viewer.go
index 6e75942..b0cbb48 100644
--- a/tools/viewer/viewer.go
+++ b/tools/viewer/viewer.go
@@ -122,6 +122,9 @@ func (s *scene) updateTexture() error {
 }
 
 func main() {
+	platform.Initialize()
+	defer platform.Shutdown()
+
 	var (
 		palettePath = flag.String("palette", "", "path to palette file")
 	)