[GS] Get most modern Road Type for player

[Luke Vo]

In one of my mod, I needed to create road, so here is the snippet that should returns the best road that a player can build. Just edited so that it can now recognize TRAIT_CIVILIZATION_SATRAPIES trait (by being Persian currently). I do that by using getPlayerTraits function from my other thread.

playerTraitsCache = {};

function GetPlayerRouteType(player)
    local route = nil;
    local playerEra = GameInfo.Eras[player:GetEra()];
   
    for routeType in GameInfo.Routes() do 
        if route == nil then
            route = routeType;
        else
            if (route.PlacementValue < routeType.PlacementValue) then
                local canBuild = true;
               
                -- Era requirement
                local prereq_era = GameInfo.Eras[routeType.PrereqEra];
                if prereq_era and playerEra.ChronologyIndex < prereq_era.ChronologyIndex  then
                    canBuild = false;
                end
               
                -- Tech requirement
                if canBuild and GameInfo.Routes_XP2 then
                    local routeXp2 = GameInfo.Routes_XP2[routeType.RouteType];
                   
                    if (routeXp2 and routeXp2.PrereqTech) then
                        local playerTech = player:GetTechs();
                        local requiredTech = GameInfo.Technologies[routeXp2.PrereqTech];
                       
                        if not playerTech:HasTech(requiredTech.Index) then
                            canBuild = false;
                        end
                    end
                end
               
                if (canBuild) then
                    route = routeType;
                end
            end
        end
    end
   
    -- See if player has TRAIT_CIVILIZATION_SATRAPIES trait
    local playerId = player:GetID();
    if (not playerTraitsCache[playerId]) then
        playerTraitsCache[playerId] = getPlayerTraits(playerId);
    end
   
    if (playerTraitsCache[playerId]["TRAIT_CIVILIZATION_SATRAPIES"]) then
        -- See if there is a road with higher placement value
        for routeType in GameInfo.Routes() do
            if (routeType.PlacementValue == route.PlacementValue + 1) then
                route = routeType;
                break;
            end
        end
    end
   
    return route;
end

function getPlayerTraits(playerId: number)
    local result = {};
    local playerConfig = PlayerConfigurations[playerId];
   
    -- Civ Trait
    local playerCiv = playerConfig:GetCivilizationTypeName();
    for row in GameInfo.CivilizationTraits() do
        if (row.CivilizationType == playerCiv) then
            result[row.TraitType] = true;
        end
    end
   
    -- Leader Trait
    local playerLeader = playerConfig:GetLeaderTypeName();
    for row in GameInfo.LeaderTraits() do
        if (row.LeaderType == playerLeader) then
            result[row.TraitType] = true;
        end
    end
   
    return result;
end

Example usage:

        local plot = Map.GetPlot(tileX, tileY);
      
        if (not plot:IsWater()) then
            local buildingRouteType = GetPlayerRouteType(player);
            local currentRouteType = plot:GetRouteType();
          
            if currentRouteType == -1 or buildingRouteType.PlacementValue > GameInfo.Routes[currentRouteType].PlacementValue then
                RouteBuilder.SetRouteType(plot, buildingRouteType.Index);
            end
        end