source: branches/AlphaChannel/AI Template/Project/Lib/PlayResult.cs

using System;
using System.Collections.Generic;

namespace CevoAILib
{
        enum PlayError
        {
                None = -1,

                // internal, should not occur
                InternalError_UnknownCommand = 1,
                InternalError_InvalidData = 0,

                // general
                NoTurn = 2, // command only allowed during player's turn
                RulesViolation = 3, // general violation of game rules
                PrerequisitesMissed = 4, // the prerequisites for this command are not fully met
                InvalidLocation = 512, // location is not valid

                // unit movement
                NoTime_Move = 8, // normal unit move: too few movement points left
                NoTime_Load = 9, // load unit: too few movement points left
                DomainMismatch = 17, // move/attack: action not allowed for this unit domain
                NoNavigation = 25, // unit move: not possible, open sea without navigation
                NoRoad = 23, // unit move: not possible, no road
                NoCapturer = 18, // unit move: this type of unit is not allowed to capture a city
                ZoCViolation = 20, // unit move: not possible, ZoC violation
                TreatyViolation = 21, // move/attack: not possible, peace treaty violation
                SubmarineBlock = 19, // unit move: not possible, destination tile occupied by hidden foreign submarine
                StealthUnitBlock = 26, // unit move: not possible, destination tile occupied by foreign stealth unit
                NoLoadCapacity = 27, // load to transport: no more transport capacity
                NoWay = 513,
                RecoverFirst = 514,
                Incomplete = 515,

                // fighting
                NoTime_Attack = 10, // attack: no movement points left
                NoTime_Bombard = 11, // bombard city: too few movement points left
                NoTime_Expel = 12, // expel spy: too few movement points left
                NoBombarder = 28, // bombardment impossible because no attack power

                // settlers
                NoCityTerrain = 34, // found city: not possible in this terrain
                NoBridgeBuilding = 35,
                DeadLands = 22, // sStartJob: not possible, dead lands
                MaxSize = 32, // add to city: bigger size not allowed due to missing aqueduct/sewer

                // city
                RebuildSellOnlyOnce = 88, // sell/rebuild city improvement: only once per city and turn!
                UselessBuilding = 89, // city project: more advanced improvement already exists
                OutOfControl = 90, // buy/sell/rebuild improvement: not in anarchy, not in captured cities
                LocationNotAvailable = 80, // set exploited locations
                TooManyLocations = 81, // set exploited locations

                // model
                ResearchInProgress = 516, // blueprint can't be changed during military research

                // negotiation
                InvalidOffer = 48,
                OfferNotAcceptable = 49,
                CancelTreatyRush = 50,
        }

        struct PlayResult
        {
                readonly int code;

                public PlayResult(int code) { this.code = code; }
                public PlayResult(PlayError error) { this.code = (int)error & 0xFFFF; }

                public override string ToString()
                {
                        if ((code & Protocol.rExecuted) != 0)
                                return "OK";
                        else
                                return string.Format("{0}", Error);
                }

                public PlayError Error
                {
                        get
                        {
                                if (OK)
                                        return PlayError.None;
                                else
                                        return (PlayError)(code & 0xFFFF);
                        }
                }

                public bool OK { get { return (code & Protocol.rExecuted) != 0; } }
                public bool Effective { get { return (code & Protocol.rEffective) != 0; } }
                public bool UnitRemoved { get { return (code & Protocol.rUnitRemoved) != 0; } }
                public bool EnemyDestroyed { get { return OK && (code & 0xFFFF) == Protocol.eEnemyDestroyed; } }
                public bool NewUnitOrCitySpotted { get { return (code & Protocol.rEnemySpotted) != 0; } }

                public static PlayResult Success { get { return new PlayResult(Protocol.rExecuted | Protocol.rEffective); } }
                public static PlayResult NoChange { get { return new PlayResult(Protocol.rExecuted); } }
        }
}