Idea to prevent bankrupting yourself with the last share

9300.diff

diff --git a/src/economy.cpp b/src/economy.cpp
index 35fcf57a5..089d8d6d0 100644
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -1969,7 +1969,7 @@ void CompaniesMonthlyLoop()
 	HandleEconomyFluctuations();
 }
 
-static void DoAcquireCompany(Company *c)
+static void DoAcquireCompany(Company *c, bool take_over)
 {
 	CompanyID ci = c->index;
 
@@ -1977,7 +1977,7 @@ static void DoAcquireCompany(Company *c)
 	cni->FillData(c, Company::Get(_current_company));
 
 	SetDParam(0, STR_NEWS_COMPANY_MERGER_TITLE);
-	SetDParam(1, c->bankrupt_value == 0 ? STR_NEWS_MERGER_TAKEOVER_TITLE : STR_NEWS_COMPANY_MERGER_DESCRIPTION);
+	SetDParam(1, take_over ? STR_NEWS_MERGER_TAKEOVER_TITLE : STR_NEWS_COMPANY_MERGER_DESCRIPTION);
 	SetDParamStr(2, cni->company_name);
 	SetDParamStr(3, cni->other_company_name);
 	SetDParam(4, c->bankrupt_value);
@@ -1987,14 +1987,6 @@ static void DoAcquireCompany(Company *c)
 
 	ChangeOwnershipOfCompanyItems(ci, _current_company);
 
-	if (c->bankrupt_value == 0) {
-		Company *owner = Company::Get(_current_company);
-		/* Get the bank balance of the company you acquired. */
-		owner->money += c->money;
-		/* Pay back the loan in full. */
-		owner->money -= c->current_loan;
-	}
-
 	if (c->is_ai) AI::Stop(c->index);
 
 	DeleteCompanyWindows(ci);
@@ -2033,27 +2025,28 @@ CommandCost CmdBuyShareInCompany(TileIndex tile, DoCommandFlag flags, uint32 p1,
 	/* Those lines are here for network-protection (clients can be slow) */
 	if (GetAmountOwnedBy(c, COMPANY_SPECTATOR) == 0) return cost;
 
+	bool acquire_company = GetAmountOwnedBy(c, _current_company) == 3;
 	if (GetAmountOwnedBy(c, COMPANY_SPECTATOR) == 1) {
 		if (!c->is_ai) return cost; //  We can not buy out a real company (temporarily). TODO: well, enable it obviously.
 
-		if (GetAmountOwnedBy(c, _current_company) == 3 && !MayCompanyTakeOver(_current_company, target_company)) return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
+		if (acquire_company && !MayCompanyTakeOver(_current_company, target_company)) return_cmd_error(STR_ERROR_TOO_MANY_VEHICLES_IN_GAME);
 	}
 
-
 	cost.AddCost(CalculateCompanyValue(c) >> 2);
+	if (acquire_company) {
+		/* Get the bank balance of the company you acquired. */
+		cost.AddCost(-c->money);
+		/* Pay back the loan in full. */
+		cost.AddCost(c->current_loan);
+	}
+
 	if (flags & DC_EXEC) {
 		Owner *b = c->share_owners;
 
 		while (*b != COMPANY_SPECTATOR) b++; // share owners is guaranteed to contain at least one COMPANY_SPECTATOR
 		*b = _current_company;
 
-		for (int i = 0; c->share_owners[i] == _current_company;) {
-			if (++i == 4) {
-				c->bankrupt_value = 0;
-				DoAcquireCompany(c);
-				break;
-			}
-		}
+		if (acquire_company) DoAcquireCompany(c, true);
 		InvalidateWindowData(WC_COMPANY, target_company);
 		CompanyAdminUpdate(c);
 	}
@@ -2132,7 +2125,7 @@ CommandCost CmdBuyCompany(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 	CommandCost cost(EXPENSES_OTHER, c->bankrupt_value);
 
 	if (flags & DC_EXEC) {
-		DoAcquireCompany(c);
+		DoAcquireCompany(c, false);
 	}
 	return cost;
 }