SCUMM: Enable Day of the Tentacle easter egg

Instead of returning to the launcher, a game may now specify a list
of "chained" games and optional save slots. The first game is popped
from the list and started. Quitting still quits the entire ScummVM.
It seemed like the sensible thing to do.

4 files changed, 48 insertions, 6 deletions

diff --git a/engines/scumm/saveload.cpp b/engines/scumm/saveload.cpp
index 0c0f6be73b..e5673c1803 100644
--- a/engines/scumm/saveload.cpp
+++ b/engines/scumm/saveload.cpp
@@ -149,7 +149,7 @@ void ScummEngine::requestSave(int slot, const Common::String &name) {
 
 void ScummEngine::requestLoad(int slot) {
 	_saveLoadSlot = slot;
-	_saveTemporaryState = false;
+	_saveTemporaryState = (slot == 100);
 	_saveLoadFlag = 2;		// 2 for load
 }
 
diff --git a/engines/scumm/script_v6.cpp b/engines/scumm/script_v6.cpp
index d2f4133f74..6c81f17f2f 100644
--- a/engines/scumm/script_v6.cpp
+++ b/engines/scumm/script_v6.cpp
@@ -2597,7 +2597,11 @@ void ScummEngine_v6::o6_kernelSetFunctions() {
 		fadeIn(args[1]);
 		break;
 	case 8:
-		startManiac();
+		if (startManiac()) {
+			// This is so that the surprised exclamation happens
+			// after we return to the game again, not before.
+			o6_breakHere();
+		}
 		break;
 	case 9:
 		killAllScriptsExceptCurrent();
diff --git a/engines/scumm/scumm.cpp b/engines/scumm/scumm.cpp
index 6040344c2c..34ae957951 100644
--- a/engines/scumm/scumm.cpp
+++ b/engines/scumm/scumm.cpp
@@ -2597,9 +2597,47 @@ void ScummEngine_v90he::runBootscript() {
 }
 #endif
 
-void ScummEngine::startManiac() {
-	debug(0, "stub startManiac()");
-	displayMessage(0, "%s", _("Usually, Maniac Mansion would start now. But ScummVM doesn't do that yet. To play it, go to 'Add Game' in the ScummVM start menu and select the 'Maniac' directory inside the Tentacle game directory."));
+bool ScummEngine::startManiac() {
+	Common::String currentPath = ConfMan.get("path");
+	Common::String maniacTarget;
+
+	// Look for a game with a game path pointing to a 'Maniac' directory
+	// as a subdirectory to the current game.
+	Common::ConfigManager::DomainMap::iterator iter = ConfMan.beginGameDomains();
+	for (; iter != ConfMan.endGameDomains(); ++iter) {
+		Common::ConfigManager::Domain &dom = iter->_value;
+		Common::String path = dom.getVal("path");
+
+		if (path.hasPrefix(currentPath)) {
+			path.erase(0, currentPath.size() + 1);
+			if (path.equalsIgnoreCase("maniac")) {
+				maniacTarget = dom.getVal("gameid");
+				break;
+			}
+		}
+	}
+
+	if (!maniacTarget.empty()) {
+		// Request a temporary save game to be made.
+		_saveLoadFlag = 1;
+		_saveLoadSlot = 100;
+		_saveTemporaryState = true;
+
+		// Set up the chanined games to Maniac Mansion, and then back
+		// to the current game again with that save slot.
+		ConfMan.set("chained_games", maniacTarget + "," + ConfMan.getActiveDomainName() + ":100", Common::ConfigManager::kTransientDomain);
+
+		// Force a return to the launcher. This will start the first
+		// chained game.
+		Common::EventManager *eventMan = g_system->getEventManager();
+		Common::Event event;
+		event.type = Common::EVENT_RTL;
+		eventMan->pushEvent(event);
+		return true;
+	} else {
+		displayMessage(0, "%s", _("Usually, Maniac Mansion would start now. But for that to work, the game files for Maniac Mansion have to be in the 'Maniac' directory inside the Tentacle game directory, and the game has to be added to ScummVM."));
+		return false;
+	}
 }
 
 #pragma mark -
diff --git a/engines/scumm/scumm.h b/engines/scumm/scumm.h
index 967909e505..30b4d61880 100644
--- a/engines/scumm/scumm.h
+++ b/engines/scumm/scumm.h
@@ -654,7 +654,7 @@ protected:
 	int	getScriptSlot();
 
 	void startScene(int room, Actor *a, int b);
-	void startManiac();
+	bool startManiac();
 
 public:
 	void runScript(int script, bool freezeResistant, bool recursive, int *lvarptr, int cycle = 0);