(svn r1561) Fix: autoreplacing a singleheaded engine into a dualheaded engine now adds the the rear engine

autoreplacing a dualheaded engine into a singleheaded engine now sells the rear engine
as a sideeffect of this, the price for replacing both engines are now added and displayed once from the depot(instead of two identical numbers written on top of each other, looking like one)
fix: cost for autorenew dualheaded engines were doubled and their value where doubled too

3 files changed, 111 insertions, 53 deletions

diff --git a/train_cmd.c b/train_cmd.c
index 73fd22399..0f0fd6c5a 100644
--- a/train_cmd.c
+++ b/train_cmd.c
@@ -365,6 +365,35 @@ int32 EstimateTrainCost(const RailVehicleInfo *rvi)
 	return (rvi->base_cost * (_price.build_railvehicle >> 3)) >> 5;
 }
 
+void AddRearEngineToMultiheadedTrain(Vehicle *v, Vehicle *u, bool building) 
+{
+	u->direction = v->direction;
+	u->owner = v->owner;
+	u->tile = v->tile;
+	u->x_pos = v->x_pos;
+	u->y_pos = v->y_pos;
+	u->z_pos = v->z_pos;
+	u->z_height = 6;
+	u->u.rail.track = 0x80;
+	v->u.rail.first_engine = 0xffff;
+	u->vehstatus = v->vehstatus & ~VS_STOPPED;
+	u->subtype = 2;
+	u->spritenum = v->spritenum + 1;
+	u->cargo_type = v->cargo_type;
+	u->cargo_cap = v->cargo_cap;
+	u->u.rail.railtype = v->u.rail.railtype;
+	if (building) v->next = u;
+	u->engine_type = v->engine_type;
+	u->build_year = v->build_year;
+	if (building) 
+		v->value = u->value = v->value >> 1;
+	else
+		u->value = v->value;
+	u->type = VEH_Train;
+	u->cur_image = 0xAC2;
+	VehiclePositionChanged(u);
+}
+
 /* Build a railroad vehicle
  * p1 = vehicle type id
  */
@@ -442,32 +471,8 @@ int32 CmdBuildRailVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 
 			VehiclePositionChanged(v);
 
-			if (rvi->flags&RVI_MULTIHEAD && (u=AllocateVehicle()) != NULL) {
-				u->direction = v->direction;
-				u->owner = v->owner;
-				u->tile = v->tile;
-				u->x_pos = v->x_pos;
-				u->y_pos = v->y_pos;
-				u->z_pos = v->z_pos;
-				u->z_height = 6;
-				u->u.rail.track = 0x80;
-				v->u.rail.first_engine = 0xffff;
-				u->vehstatus = VS_HIDDEN | VS_DEFPAL;
-				u->subtype = 2;
-				u->spritenum = v->spritenum + 1;
-				u->cargo_type = v->cargo_type;
-				u->cargo_cap = v->cargo_cap;
-				u->u.rail.railtype = v->u.rail.railtype;
-//				u->next_in_chain = 0xffff;
-				v->next = u;
-				u->engine_type = v->engine_type;
-				u->build_year = v->build_year;
-				v->value = u->value = v->value >> 1;
-//				u->day_counter = 0;
-				u->type = VEH_Train;
-				u->cur_image = 0xAC2;
-				VehiclePositionChanged(u);
-			}
+			if (rvi->flags&RVI_MULTIHEAD && (u = AllocateVehicle()) != NULL)
+				AddRearEngineToMultiheadedTrain(v, u, true);
 
 			UpdateTrainAcceleration(v);
 			NormalizeTrainVehInDepot(v);
diff --git a/vehicle.c b/vehicle.c
index b0a86e6a6..4e1f9f0d9 100644
--- a/vehicle.c
+++ b/vehicle.c
@@ -1321,7 +1321,9 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 	uint16 new_engine_type = (uint16)(p2 & 0xFFFF);
 	uint32 autorefit_money = (p2  >> 16) * 100000;
 	Vehicle *v = GetVehicle(p1);
-	int cost, build_cost;
+	int cost, build_cost, rear_engine_cost = 0;
+	Vehicle *u = v;
+	byte old_engine_type = v->engine_type;
 
 	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);
 
@@ -1347,12 +1349,42 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 
 	/* In a rare situation, when 2 clients are connected to 1 company and have the same
 	    settings, a vehicle can be replaced twice.. check if this is the situation here */
-	if (v->engine_type == new_engine_type && v->age == 0)
+	if (old_engine_type == new_engine_type && v->age == 0)
 		return CMD_ERROR;
+		
+	if ( v->type == VEH_Train ) {
+		u = GetLastVehicleInChain(v);
+		if ( RailVehInfo(new_engine_type)->flags & RVI_MULTIHEAD )
+			build_cost = build_cost >> 1;   //multiheaded engines have EstimateTrainCost() for both engines
+		
+		if ( old_engine_type != new_engine_type ) {
+		
+			// prevent that the rear engine can get replaced to something else than the front engine
+			if ( v->u.rail.first_engine != 0xffff && RailVehInfo(old_engine_type)->flags & RVI_MULTIHEAD && RailVehInfo(old_engine_type)->flags ) {
+				Vehicle *first = GetFirstVehicleInChain(v);
+				if ( first->engine_type != new_engine_type ) return CMD_ERROR;
+			}
+			
+			// checks if the engine is the first one
+			if ( v->u.rail.first_engine == 0xffff ) {
+				if ( RailVehInfo(new_engine_type)->flags & RVI_MULTIHEAD ) {
+					if ( u->engine_type == old_engine_type && v->next != NULL) {
+						rear_engine_cost = build_cost - u->value;
+					} else {
+						rear_engine_cost = build_cost;
+					}
+				} else {
+					if ( u->engine_type == old_engine_type && RailVehInfo(old_engine_type)->flags & RVI_MULTIHEAD) {
+						if (v->next != NULL) rear_engine_cost = -u->value;
+					}
+				}
+			 }
+		}
+	}
 
 	/* Check if there is money for the upgrade.. if not, give a nice news-item
 	    (that is needed, because this CMD is called automaticly) */
-	if ( DEREF_PLAYER(v->owner)->money64 < (int32)(autorefit_money + build_cost - v->value)) {
+	if ( DEREF_PLAYER(v->owner)->money64 < (int32)(autorefit_money + build_cost + rear_engine_cost - v->value)) {
 		if (( _local_player == v->owner ) && ( v->unitnumber != 0 )) {  //v->unitnumber = 0 for train cars
 			int message;
 			SetDParam(0, v->unitnumber);
@@ -1370,18 +1402,27 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 
 		return CMD_ERROR;
 	}
-	cost = build_cost - v->value;
+	cost = build_cost - v->value + rear_engine_cost;
 
 
 	if (flags & DC_EXEC) {
+		/* We do not really buy a new vehicle, we upgrade the old one */
 		Engine *e;
 		e = DEREF_ENGINE(new_engine_type);
 
-		// TODO make it check if refit is possible before actually doing it
+		v->reliability = e->reliability;
+		v->reliability_spd_dec = e->reliability_spd_dec;
+		v->age = 0;
+
+		v->date_of_last_service = _date;
+		v->build_year = _cur_year;
+
+		v->value = build_cost;
 
-		/* We do not really buy a new vehicle, we upgrade the old one */
+		InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
+
+	
 		if (v->engine_type != new_engine_type) {
-			byte old_engine = v->engine_type;
 			byte sprite = v->spritenum;
 			byte cargo_type = v->cargo_type;
 			v->engine_type = new_engine_type;
@@ -1390,11 +1431,11 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 			/* Update limits of the vehicle (for when upgraded) */
 			switch (v->type) {
 			case VEH_Train:
-			// using if (true) to declare the const
 				{
 				const RailVehicleInfo *rvi = RailVehInfo(new_engine_type);
-				const RailVehicleInfo *rvi2 = RailVehInfo(old_engine);
+				const RailVehicleInfo *rvi2 = RailVehInfo(old_engine_type);
 				byte capacity = rvi->capacity;
+				Vehicle *first = GetFirstVehicleInChain(v);
 
 				/* rvi->image_index is the new sprite for the engine. Adding +1 makes the engine head the other way
 				if it is a multiheaded engine (rear engine)
@@ -1402,7 +1443,7 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 				v->spritenum = rvi->image_index + (( rvi->flags & RVI_MULTIHEAD && sprite - rvi2->image_index) ? 1 : 0);
 
 				// turn the last engine in a multiheaded train if needed
-				if ( v->next == NULL && rvi->flags & RVI_MULTIHEAD && v->spritenum == rvi->image_index )
+				if ( v->next == NULL && v->u.rail.first_engine != 0xffff && rvi->flags & RVI_MULTIHEAD && v->spritenum == rvi->image_index )
 					v->spritenum++;
 
 				v->cargo_type = rvi->cargo_type;
@@ -1420,11 +1461,34 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 				} else {
 					v->cargo_type = rvi->cargo_type;
 				}
+				
+				if ( rvi2->flags & RVI_MULTIHEAD && !(rvi->flags & RVI_MULTIHEAD) &&  v->index == first->index) {
+					if (old_engine_type == u->engine_type ) {
+						u = GetLastVehicleInChain(v);
+						Vehicle *w = GetPrevVehicleInChain(u);
+						w->next = NULL;
+						DeleteVehicle(u);
+					}
+				}
+				
+				if ( rvi->flags & RVI_MULTIHEAD && rvi2->flags & RVI_MULTIHEAD &&  v->index == first->index ) {
+					CmdReplaceVehicle(x, y, flags, u->index, p2);
+				}
+				
+				if ( rvi->flags & RVI_MULTIHEAD && !(rvi2->flags & RVI_MULTIHEAD) &&  v->index == first->index ) {
+					if ( old_engine_type != u->engine_type ) {
+						Vehicle *w;
+						if ( (w=AllocateVehicle()) != NULL ) {
+							AddRearEngineToMultiheadedTrain(v,w, false);
+							u->next = w;
+						}
+					}
+				}
+				
 				break;
 				}
 			case VEH_Road:
-			// using if (true) to declare the const
-				if (true) {
+				{
 				const RoadVehicleInfo *rvi = RoadVehInfo(new_engine_type);
 
 				v->spritenum = rvi->image_index;
@@ -1434,8 +1498,7 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 				break;
 				}
 			case VEH_Ship:
-			// using if (true) to declare the const
-				if (true) {
+				{
 				const ShipVehicleInfo *svi = ShipVehInfo(new_engine_type);
 
 				v->spritenum = svi->image_index;
@@ -1450,8 +1513,7 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 				break;
 				}
 			case VEH_Aircraft:
-			// using if (true) to declare the const
-				if (true) {
+				{
 				const AircraftVehicleInfo *avi = AircraftVehInfo(new_engine_type);
 				Vehicle *u;
 
@@ -1480,17 +1542,6 @@ int32 CmdReplaceVehicle(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 					v->cargo_count = v->cargo_cap;
 			}
 		}
-
-		v->reliability = e->reliability;
-		v->reliability_spd_dec = e->reliability_spd_dec;
-		v->age = 0;
-
-		v->date_of_last_service = _date;
-		v->build_year = _cur_year;
-
-		v->value = build_cost;
-
-		InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
 	}
 	//needs to be down here because refitting will change SET_EXPENSES_TYPE if called
 	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);
diff --git a/vehicle.h b/vehicle.h
index 864d382cf..a5803750c 100644
--- a/vehicle.h
+++ b/vehicle.h
@@ -284,6 +284,8 @@ void ViewportAddVehicles(DrawPixelInfo *dpi);
 
 void TrainEnterDepot(Vehicle *v, uint tile);
 
+void AddRearEngineToMultiheadedTrain(Vehicle *v, Vehicle *u, bool building) ;
+
 /* train_cmd.h */
 int GetTrainImage(Vehicle *v, byte direction);
 int GetAircraftImage(Vehicle *v, byte direction);