cmd: merge ship types

pkg/model/game/ship.go

@@ -44,6 +44,14 @@ type Fleet struct {
 	ShipGroups []ShipGroup `json:"group"`
 }
 
+func (st ShipType) Equal(o ShipType) bool {
+	return st.Drive == o.Drive &&
+		st.Weapons == o.Weapons &&
+		st.Armament == o.Armament &&
+		st.Shields == o.Shields &&
+		st.Cargo == o.Cargo
+}
+
 func (st ShipType) EmptyMass() float64 {
 	shipMass := st.Drive + st.Shields + st.Cargo + st.WeaponsMass()
 	return shipMass
@@ -197,6 +205,53 @@ func (g Game) createShipTypeInternal(ri int, name string, d, w, s, c float64, a
 	return nil
 }
 
+func (g Game) MergeShipType(race, name, targetName string) error {
+	ri, err := g.raceIndex(race)
+	if err != nil {
+		return err
+	}
+	return g.mergeShipTypeInternal(ri, name, targetName)
+}
+
+func (g Game) mergeShipTypeInternal(ri int, name, targetName string) error {
+	st := slices.IndexFunc(g.Race[ri].ShipTypes, func(st ShipType) bool { return st.Name == name })
+	if st < 0 {
+		return e.NewEntityNotExistsError("source ship type %w", name)
+	}
+	if name == targetName {
+		return e.NewEntityTypeNameEqualityError("ship type %q", targetName)
+	}
+	tt := slices.IndexFunc(g.Race[ri].ShipTypes, func(st ShipType) bool { return st.Name == targetName })
+	if tt < 0 {
+		return e.NewEntityNotExistsError("target ship type %w", name)
+	}
+	if !g.Race[ri].ShipTypes[st].Equal(g.Race[ri].ShipTypes[tt]) {
+		return e.NewMergeShipTypeNotEqualError()
+	}
+
+	// switch planet productions to the new type
+	for pl := range g.Map.Planet {
+		if g.Map.Planet[pl].Owner == g.Race[ri].ID &&
+			g.Map.Planet[pl].Production.Production == ProductionShip &&
+			g.Map.Planet[pl].Production.SubjectID != nil &&
+			*g.Map.Planet[pl].Production.SubjectID == g.Race[ri].ShipTypes[st].ID {
+			g.Map.Planet[pl].Production.SubjectID = &g.Race[ri].ShipTypes[tt].ID
+		}
+	}
+
+	// switch ship groups to the new type
+	for sg := range g.Race[ri].ShipGroups {
+		if g.Race[ri].ShipGroups[sg].TypeID == g.Race[ri].ShipTypes[st].ID {
+			g.Race[ri].ShipGroups[sg].TypeID = g.Race[ri].ShipTypes[tt].ID
+		}
+	}
+
+	// remove the source type
+	g.Race[ri].ShipTypes = append(g.Race[ri].ShipTypes[:st], g.Race[ri].ShipTypes[st+1:]...)
+
+	return nil
+}
+
 func checkShipTypeValues(d, w, s, c float64, a int) error {
 	if !checkShipTypeValueDWSC(d) {
 		return e.NewDriveValueError(d)