From e8c0b5566a63f6f565c97df1063ab8b0b76302d8 Mon Sep 17 00:00:00 2001
From: Jacek Olszak <jacekolszak@gmail.com>
Date: Sun, 13 Aug 2023 15:56:14 +0200
Subject: [PATCH] Add next [n] - go to next frame from devtools

User can go to next frame when the game is paused. To do so he can:

* issue next command in REPL terminal (or 'n')
* press n in game window
---
 devtools/control.go                          | 14 ++++++++++++--
 devtools/internal/help/help.go               |  2 +-
 devtools/internal/interpreter/interpreter.go |  3 +++
 devtools/scripting.go                        |  2 ++
 devtools/update.go                           |  9 +++++++++
 5 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/devtools/control.go b/devtools/control.go
index d5cdb342..fcfb9809 100644
--- a/devtools/control.go
+++ b/devtools/control.go
@@ -11,8 +11,9 @@ import (
 )
 
 var (
-	gamePaused     bool
-	timeWhenPaused float64
+	gamePaused       bool
+	pauseOnNextFrame bool
+	timeWhenPaused   float64
 )
 
 var helpShown bool
@@ -35,3 +36,12 @@ func resumeGame() {
 	snapshot.Draw()
 	fmt.Println("Game resumed")
 }
+
+func resumeUntilNextFrame() {
+	if gamePaused {
+		resumeGame()
+		pauseOnNextFrame = true
+	} else {
+		fmt.Println("Game not paused")
+	}
+}
diff --git a/devtools/internal/help/help.go b/devtools/internal/help/help.go
index fed74f34..055c65de 100644
--- a/devtools/internal/help/help.go
+++ b/devtools/internal/help/help.go
@@ -27,7 +27,7 @@ func PrintHelp(topic string) error {
 			"\n\n" +
 			"Type help topic for more information. For example: help pi or help pi.Spr" +
 			"\n\n" +
-			"Available commands: help [h], pause [p], resume [r], undo [u]",
+			"Available commands: help [h], pause [p], resume [r], undo [u], next [n]",
 		)
 		return nil
 	default:
diff --git a/devtools/internal/interpreter/interpreter.go b/devtools/internal/interpreter/interpreter.go
index 712c98d9..d1f93765 100644
--- a/devtools/internal/interpreter/interpreter.go
+++ b/devtools/internal/interpreter/interpreter.go
@@ -191,6 +191,7 @@ const (
 	Paused         EvalResult = 3
 	Undoed         EvalResult = 4
 	Continued      EvalResult = 5
+	NextFrame      EvalResult = 6
 )
 
 func (i Instance) Eval(cmd string) (EvalResult, error) {
@@ -199,6 +200,8 @@ func (i Instance) Eval(cmd string) (EvalResult, error) {
 	if isHelpCommand(trimmedCmd) {
 		topic := strings.Trim(strings.TrimLeft(trimmedCmd, "help"), " ")
 		return HelpPrinted, i.printHelp(topic)
+	} else if trimmedCmd == "next" || trimmedCmd == "n" {
+		return NextFrame, nil
 	} else if trimmedCmd == "resume" || trimmedCmd == "r" {
 		return Resumed, nil
 	} else if trimmedCmd == "pause" || trimmedCmd == "p" {
diff --git a/devtools/scripting.go b/devtools/scripting.go
index 3a4492e9..af2b3f79 100644
--- a/devtools/scripting.go
+++ b/devtools/scripting.go
@@ -70,6 +70,8 @@ func evaluateNextCommandFromTerminal() {
 		case interpreter.Undoed:
 			snapshot.Undo()
 			fmt.Println("Undoed last draw operation")
+		case interpreter.NextFrame:
+			resumeUntilNextFrame()
 		}
 
 		if result == interpreter.Continued {
diff --git a/devtools/update.go b/devtools/update.go
index 98c3f240..a8324e40 100644
--- a/devtools/update.go
+++ b/devtools/update.go
@@ -17,7 +17,16 @@ func updateDevTools() {
 		}
 	}
 
+	if pauseOnNextFrame {
+		pauseGame()
+		pauseOnNextFrame = false
+	}
+
 	if gamePaused {
+		if key.Btnp(key.N) {
+			resumeUntilNextFrame()
+		}
+
 		inspector.Update()
 	}