package de.peeeq.wurstscript.translation.imoptimizer;

import de.peeeq.wurstscript.WurstOperator;
import de.peeeq.wurstscript.jassIm.*;
import de.peeeq.wurstscript.translation.imtranslation.ImHelper;
import de.peeeq.wurstscript.translation.imtranslation.ImTranslator;
import io.vavr.collection.HashSet;
import io.vavr.collection.Set;

import java.util.ListIterator;

/**
 * this optimization is supposed to remove useless calls like
 * <p>
 * I2S(5)
 * <p>
 * when the result is not used
 */
public class UselessFunctionCallsRemover implements OptimizerPass {
    public int totalCallsRemoved = 0;

    public int optimize(ImTranslator trans) {
        totalCallsRemoved = 0;
        ImProg prog = trans.getImProg();
        for (ImFunction func : prog.getFunctions()) {
            optimizeFunc(func, trans);
        }
        return totalCallsRemoved;
    }

    @Override
    public String getName() {
        return "Useless function calls removed";
    }

    private void optimizeFunc(ImFunction func, ImTranslator trans) {
        optimizeStmts(func.getBody());
        func.flatten(trans);
    }

    private void optimizeStmts(ImStmts stmts) {
        ListIterator<ImStmt> it = stmts.listIterator();
        while (it.hasNext()) {
            ImStmt s = it.next();

            if (s instanceof ImFunctionCall) {
                ImFunctionCall fc = (ImFunctionCall) s;
                if (isNativeWithoutSideEffect(fc.getFunc())) {
                    if (!isWantedError(fc)) {
                        // put arguments into a list of statements
                        ImStmts newStmts = JassIm.ImStmts();
                        for (ImExpr arg : fc.getArguments()) {
                            // remove from current call
                            arg.setParent(null);
                            // and move to new statements
                            newStmts.add(arg);
                        }
                        s = ImHelper.statementExprVoid(newStmts);
                        it.set(s);
                        totalCallsRemoved++;
                    }
                }
            }
            optimizeChildren(s);
        }
    }

    /**
     * a call like fooo(_ / 0) is considered a wanted error and kept
     */
    private boolean isWantedError(ImFunctionCall fc) {
        if (fc.getArguments().size() != 1) {
            return false;
        }
        return isDivisionByZero(fc.getArguments().get(0));
    }

    private boolean isDivisionByZero(ImExpr e) {
        if (e instanceof ImOperatorCall) {
            ImOperatorCall oc = (ImOperatorCall) e;
            if (oc.getOp() == WurstOperator.DIV_INT) {
                ImExpr dividend = oc.getArguments().get(1);
                if (dividend instanceof ImIntVal) {
                    ImIntVal v = (ImIntVal) dividend;
                    return v.getValI() == 0;
                }
            }
        }
        return false;
    }

    private void optimizeChildren(Element e) {
        for (int i = 0; i < e.size(); i++) {
            optimizeElement(e.get(i));
        }
    }

    private void optimizeElement(Element e) {
        if (e instanceof ImStmts) {
            ImStmts stmts = (ImStmts) e;
            optimizeStmts(stmts);
        } else {
            optimizeChildren(e);
        }
    }

    private boolean isNativeWithoutSideEffect(ImFunction func) {
        return func.isNative() && isFunctionWithoutSideEffect(func.getName());
    }

    /**
     * checks if the jass-function with the given name can have no side effects.
     * Note that these are not all pure functions, some of these functions depend
     * on external state, but they never change it.
     */
    public static boolean isFunctionWithoutSideEffect(String funcName) {
        return functionsWithoutSideEffects.contains(funcName);
    }

    public static boolean isFunctionPure(String funcName) {
        return pureFunctions.contains(funcName);
    }

    private static final Set<String> functionsWithoutSideEffects = HashSet.of(
        "AbilityId", "AbilityId2String", "Acos", "And", "Asin", "Atan",
        "Atan2", "ConvertAIDifficulty", "ConvertAllianceType", "ConvertAttackType", "ConvertBlendMode",
        "ConvertCameraField", "ConvertDamageType", "ConvertDialogEvent", "ConvertEffectType",
        "ConvertFGameState", "ConvertFogState", "ConvertGameDifficulty", "ConvertGameEvent",
        "ConvertGameSpeed", "ConvertGameType", "ConvertIGameState", "ConvertItemType", "ConvertLimitOp",
        "ConvertMapControl", "ConvertMapDensity", "ConvertMapFlag", "ConvertMapSetting",
        "ConvertMapVisibility", "ConvertPathingType", "ConvertPlacement", "ConvertPlayerColor",
        "ConvertPlayerEvent", "ConvertPlayerGameResult", "ConvertPlayerScore", "ConvertPlayerSlotState",
        "ConvertPlayerState", "ConvertPlayerUnitEvent", "ConvertRace", "ConvertRacePref",
        "ConvertRarityControl", "ConvertSoundType", "ConvertStartLocPrio", "ConvertTexMapFlags",
        "ConvertUnitEvent", "ConvertUnitState", "ConvertUnitType", "ConvertVersion", "ConvertVolumeGroup",
        "ConvertWeaponType", "ConvertWidgetEvent", "Cos", "Deg2Rad", "FirstOfGroup", "GetAbilityEffect",
        "GetAbilityEffectById", "GetAbilitySound", "GetAbilitySoundById", "GetAllyColorFilterState",
        "GetAttacker", "GetBuyingUnit", "GetCameraBoundMaxX", "GetCameraBoundMaxY", "GetCameraBoundMinX",
        "GetCameraBoundMinY", "GetCameraEyePositionLoc", "GetCameraEyePositionX", "GetCameraEyePositionY",
        "GetCameraEyePositionZ", "GetCameraField", "GetCameraMargin", "GetCameraTargetPositionLoc",
        "GetCameraTargetPositionX", "GetCameraTargetPositionY", "GetCameraTargetPositionZ",
        "GetCancelledStructure", "GetChangingUnit", "GetChangingUnitPrevOwner", "GetClickedButton",
        "GetClickedDialog", "GetConstructedStructure", "GetConstructingStructure", "GetCreatureDensity",
        "GetCreepCampFilterState", "GetCustomCampaignButtonVisible", "GetDecayingUnit",
        "GetDefaultDifficulty", "GetDestructableLife", "GetDestructableMaxLife", "GetDestructableName",
        "GetDestructableOccluderHeight", "GetDestructableTypeId", "GetDestructableX", "GetDestructableY",
        "GetDetectedUnit", "GetDyingUnit", "GetEnteringUnit", "GetEnumDestructable", "GetEnumItem",
        "GetEnumPlayer", "GetEnumUnit", "GetEventDamage", "GetEventDamageSource", "GetEventDetectingPlayer",
        "GetEventGameState", "GetEventPlayerChatString", "GetEventPlayerChatStringMatched",
        "GetEventPlayerState", "GetEventTargetUnit", "GetEventUnitState", "GetExpiredTimer",
        "GetFilterDestructable", "GetFilterItem", "GetFilterPlayer", "GetFilterUnit", "GetFloatGameState",
        "GetFoodMade", "GetFoodUsed", "GetGameDifficulty", "GetGamePlacement", "GetGameSpeed",
        "GetGameTypeSelected", "GetHandleId", "GetHeroAgi", "GetHeroInt", "GetHeroLevel",
        "GetHeroProperName", "GetHeroSkillPoints", "GetHeroStr", "GetHeroXP", "GetIntegerGameState",
        "GetIssuedOrderId", "GetItemCharges", "GetItemLevel", "GetItemName", "GetItemPlayer", "GetItemType",
        "GetItemTypeId", "GetItemUserData", "GetItemX", "GetItemY", "GetKillingUnit", "GetLearnedSkill",
        "GetLearnedSkillLevel", "GetLearningUnit", "GetLeavingUnit", "GetLevelingUnit",
        "GetLightningColorA", "GetLightningColorB", "GetLightningColorG", "GetLightningColorR",
        "GetLoadedUnit", "GetLocalizedHotkey", "GetLocalizedString", "GetLocationX", "GetLocationY",
        "GetLocationZ", "GetManipulatedItem", "GetManipulatingUnit", "GetObjectName", "GetOrderedUnit",
        "GetOrderPointLoc", "GetOrderPointX", "GetOrderPointY", "GetOrderTarget",
        "GetOrderTargetDestructable", "GetOrderTargetItem", "GetOrderTargetUnit", "GetOwningPlayer",
        "GetPlayerAlliance", "GetPlayerColor", "GetPlayerController", "GetPlayerHandicap",
        "GetPlayerHandicapXP", "GetPlayerId", "GetPlayerName", "GetPlayerRace", "GetPlayers",
        "GetPlayerScore", "GetPlayerSelectable", "GetPlayerSlotState", "GetPlayerStartLocation",
        "GetPlayerState", "GetPlayerStructureCount", "GetPlayerTaxRate", "GetPlayerTeam",
        "GetPlayerTechCount", "GetPlayerTechMaxAllowed", "GetPlayerTechResearched",
        "GetPlayerTypedUnitCount", "GetPlayerUnitCount", "GetRectCenterX",
        "GetRectCenterY", "GetRectMaxX", "GetRectMaxY", "GetRectMinX", "GetRectMinY", "GetRescuer",
        "GetResearched", "GetResearchingUnit", "GetResourceAmount", "GetResourceDensity",
        "GetRevivableUnit", "GetRevivingUnit", "GetSaveBasicFilename", "GetSelectedUnit", "GetSellingUnit",
        "GetSoldItem", "GetSoldUnit", "GetSoundDuration", "GetSoundFileDuration", "GetSoundIsLoading",
        "GetSoundIsPlaying", "GetSpellAbility", "GetSpellAbilityId", "GetSpellAbilityUnit",
        "GetSpellTargetDestructable", "GetSpellTargetItem", "GetSpellTargetLoc", "GetSpellTargetUnit",
        "GetSpellTargetX", "GetSpellTargetY", "GetStartLocationLoc", "GetStartLocationX",
        "GetStartLocationY", "GetStartLocPrio", "GetStartLocPrioSlot", "GetStoredBoolean",
        "GetStoredInteger", "GetStoredReal", "GetStoredString", "GetSummonedUnit", "GetSummoningUnit",
        "GetTeams", "GetTerrainCliffLevel", "GetTerrainType", "GetTerrainVariance",
        "GetTournamentFinishNowPlayer", "GetTournamentFinishNowRule",
        "GetTournamentFinishSoonTimeRemaining", "GetTournamentScore", "GetTrainedUnit",
        "GetTrainedUnitType", "GetTransportUnit", "GetTriggerDestructable", "GetTriggerEvalCount",
        "GetTriggerEventId", "GetTriggerExecCount", "GetTriggeringRegion", "GetTriggeringTrackable",
        "GetTriggeringTrigger", "GetTriggerPlayer", "GetTriggerUnit", "GetTriggerWidget",
        "GetUnitAbilityLevel", "GetUnitAcquireRange", "GetUnitCurrentOrder", "GetUnitDefaultAcquireRange",
        "GetUnitDefaultFlyHeight", "GetUnitDefaultMoveSpeed", "GetUnitDefaultPropWindow",
        "GetUnitDefaultTurnSpeed", "GetUnitFacing", "GetUnitFlyHeight", "GetUnitFoodMade",
        "GetUnitFoodUsed", "GetUnitLevel", "GetUnitLoc", "GetUnitMoveSpeed", "GetUnitName",
        "GetUnitPointValue", "GetUnitPointValueByType", "GetUnitPropWindow", "GetUnitRace",
        "GetUnitRallyDestructable", "GetUnitRallyPoint", "GetUnitRallyUnit", "GetUnitState",
        "GetUnitTurnSpeed", "GetUnitTypeId", "GetUnitUserData", "GetUnitX", "GetUnitY", "GetWidgetLife",
        "GetWidgetX", "GetWidgetY", "GetWinningPlayer", "GetWorldBounds", "HaveSavedBoolean",
        "HaveSavedHandle", "HaveSavedInteger", "HaveSavedReal", "HaveSavedString", "HaveStoredBoolean",
        "HaveStoredInteger", "HaveStoredReal", "HaveStoredString", "HaveStoredUnit", "I2R", "I2S",
        "IsCineFilterDisplayed", "IsDestructableInvulnerable", "IsFogEnabled", "IsFoggedToPlayer",
        "IsFogMaskEnabled", "IsGameTypeSupported", "IsHeroUnitId", "IsItemIdPawnable", "IsItemIdPowerup",
        "IsItemIdSellable", "IsItemInvulnerable", "IsItemOwned", "IsItemPawnable", "IsItemPowerup",
        "IsItemSellable", "IsItemVisible", "IsLeaderboardDisplayed", "IsLocationFoggedToPlayer",
        "IsLocationInRegion", "IsLocationMaskedToPlayer", "IsLocationVisibleToPlayer", "IsMapFlagSet",
        "IsMaskedToPlayer", "IsMultiboardDisplayed", "IsMultiboardMinimized", "IsNoDefeatCheat",
        "IsNoVictoryCheat", "IsPlayerAlly", "IsPlayerEnemy", "IsPlayerInForce", "IsPlayerObserver",
        "IsPlayerRacePrefSet", "IsPointBlighted", "IsPointInRegion", "IsQuestCompleted",
        "IsQuestDiscovered", "IsQuestEnabled", "IsQuestFailed", "IsQuestItemCompleted", "IsQuestRequired",
        "IsSuspendedXP", "IsTerrainPathable", "IsTimerDialogDisplayed", "IsTriggerEnabled",
        "IsTriggerWaitOnSleeps", "IsUnit", "IsUnitAlly", "IsUnitDetected", "IsUnitEnemy", "IsUnitFogged",
        "IsUnitHidden", "IsUnitIdType", "IsUnitIllusion", "IsUnitInForce", "IsUnitInGroup", "IsUnitInRange",
        "IsUnitInRangeLoc", "IsUnitInRangeXY", "IsUnitInRegion", "IsUnitInTransport", "IsUnitInvisible",
        "IsUnitLoaded", "IsUnitMasked", "IsUnitOwnedByPlayer", "IsUnitPaused", "IsUnitRace",
        "IsUnitSelected", "IsUnitType", "IsUnitVisible", "IsVisibleToPlayer", "LoadAbilityHandle",
        "LoadBoolean", "LoadBooleanExprHandle", "LoadButtonHandle", "LoadDefeatConditionHandle",
        "LoadDestructableHandle", "LoadDialogHandle", "LoadEffectHandle", "LoadFogModifierHandle",
        "LoadFogStateHandle", "LoadForceHandle", "LoadGroupHandle", "LoadHashtableHandle",
        "LoadImageHandle", "LoadInteger", "LoadItemHandle", "LoadItemPoolHandle", "LoadLeaderboardHandle",
        "LoadLightningHandle", "LoadLocationHandle", "LoadMultiboardHandle", "LoadMultiboardItemHandle",
        "LoadPlayerHandle", "LoadQuestHandle", "LoadQuestItemHandle", "LoadReal", "LoadRectHandle",
        "LoadRegionHandle", "LoadSoundHandle", "LoadStr", "LoadTextTagHandle", "LoadTimerDialogHandle",
        "LoadTimerHandle", "LoadTrackableHandle", "LoadTriggerActionHandle", "LoadTriggerConditionHandle",
        "LoadTriggerEventHandle", "LoadTriggerHandle", "LoadUbersplatHandle", "LoadUnitHandle",
        "LoadUnitPoolHandle", "LoadWidgetHandle", "Not", "Or", "OrderId", "OrderId2String", "Player", "Pow", "R2I",
        "R2S", "R2SW", "Rad2Deg", "S2I", "S2R", "Sin", "SquareRoot", "StringCase", "StringHash",
        "StringLength", "SubString", "Tan", "TimerGetElapsed", "TimerGetRemaining", "TimerGetTimeout",
        "VersionGet", "WaygateGetDestinationX", "WaygateGetDestinationY", "WaygateIsActive",
        "BlzGetTriggerPlayerMouseX", "BlzGetTriggerPlayerMouseY", "BlzGetTriggerPlayerMousePosition",
        "BlzGetTriggerPlayerMouseButton", "BlzGetAbilityTooltip", "BlzGetAbilityActivatedTooltip",
        "BlzGetAbilityExtendedTooltip", "BlzGetAbilityActivatedExtendedTooltip", "BlzGetAbilityResearchTooltip",
        "BlzGetAbilityResearchExtendedTooltip", "BlzGetAbilityIcon", "BlzGetAbilityActivatedIcon", "BlzGetAbilityPosX",
        "BlzGetAbilityPosY", "BlzGetAbilityActivatedPosX", "BlzGetAbilityActivatedPosY", "BlzGetUnitMaxHP",
        "BlzGetUnitMaxMana", "BlzGetItemDescription", "BlzGetItemTooltip", "BlzGetItemExtendedTooltip",
        "BlzGetItemIconPath", "BlzGetUnitBaseDamage", "BlzGetUnitDiceNumber", "BlzGetUnitDiceSides",
        "BlzGetUnitAttackCooldown", "BlzGetLocalSpecialEffectX", "BlzGetLocalSpecialEffectY",
        "BlzGetLocalSpecialEffectZ", "BlzGetAnimName", "BlzGetUnitArmor", "BlzIsUnitSelectable",
        "BlzIsUnitInvulnerable", "BlzGetUnitCollisionSize", "BlzGetAbilityManaCost", "BlzGetAbilityCooldown",
        "BlzGetUnitAbilityCooldown", "BlzGetUnitAbilityCooldownRemaining", "BlzGetUnitAbilityManaCost",
        "BlzGetLocalUnitZ", "BlzGetEventDamageTarget", "BlzGetEventAttackType", "BlzGetEventDamageType",
        "BlzGetEventWeaponType", "BlzGetEventIsAttack", "BlzGetUnitZ", "BlzIsSelectionEnabled",
        "BlzIsSelectionCircleEnabled", "BlzIsTargetIndicatorEnabled", "BlzGetOriginFrame", "BlzGetFrameByName",
        "BlzFrameGetName", "BlzFrameGetText", "BlzFrameGetTextSizeLimit", "BlzFrameGetEnable", "BlzFrameGetAlpha",
        "BlzFrameGetValue", "BlzFrameGetParent", "BlzFrameGetHeight", "BlzFrameGetWidth", "BlzGetTriggerFrame",
        "BlzGetTriggerFrameEvent", "BlzGetTriggerFrameValue", "BlzGetTriggerFrameText", "BlzGetTriggerSyncPrefix",
        "BlzGetTriggerPlayerKey", "BlzGetTriggerPlayerMetaKey", "BlzGetTriggerPlayerIsKeyDown",
        "BlzGetLocalClientWidth", "BlzGetLocalClientHeight", "BlzIsLocalClientActive", "BlzGetMouseFocusUnit",
        "BlzGetLocale", "BlzGetSpecialEffectScale", "BlzGetUnitAbility", "BlzGetUnitAbilityByIndex", "BlzBitOr",
        "BlzBitAnd", "BlzBitXor", "BlzGetAbilityBooleanField", "BlzGetAbilityIntegerField", "BlzGetAbilityRealField",
        "BlzGetAbilityStringField", "BlzGetAbilityBooleanLevelField", "BlzGetAbilityIntegerLevelField",
        "BlzGetAbilityRealLevelField", "BlzGetAbilityStringLevelField", "BlzGetAbilityBooleanLevelArrayField",
        "BlzGetAbilityIntegerLevelArrayField", "BlzGetAbilityRealLevelArrayField", "BlzGetAbilityStringLevelArrayField",
        "BlzGetItemAbilityByIndex", "BlzGetItemAbility", "BlzGetItemBooleanField", "BlzGetItemIntegerField",
        "BlzGetItemRealField", "BlzGetItemStringField", "BlzGetUnitBooleanField", "BlzGetUnitIntegerField",
        "BlzGetUnitRealField", "BlzGetUnitStringField", "BlzGetUnitWeaponBooleanField", "BlzGetUnitWeaponIntegerField",
        "BlzGetUnitWeaponRealField", "BlzGetUnitWeaponStringField", "BlzGetUnitSkin", "BlzGetItemSkin",
        "BlzGetPlayerTownHallCount"
        );

    private static final Set<String> pureFunctions = HashSet.of(
        "AbilityId", "AbilityId2String", "Acos", "And", "Asin", "Atan",
        "Atan2", "ConvertAIDifficulty", "ConvertAllianceType", "ConvertAttackType", "ConvertBlendMode",
        "ConvertCameraField", "ConvertDamageType", "ConvertDialogEvent", "ConvertEffectType",
        "ConvertFGameState", "ConvertFogState", "ConvertGameDifficulty", "ConvertGameEvent",
        "ConvertGameSpeed", "ConvertGameType", "ConvertIGameState", "ConvertItemType", "ConvertLimitOp",
        "ConvertMapControl", "ConvertMapDensity", "ConvertMapFlag", "ConvertMapSetting",
        "ConvertMapVisibility", "ConvertPathingType", "ConvertPlacement", "ConvertPlayerColor",
        "ConvertPlayerEvent", "ConvertPlayerGameResult", "ConvertPlayerScore", "ConvertPlayerSlotState",
        "ConvertPlayerState", "ConvertPlayerUnitEvent", "ConvertRace", "ConvertRacePref",
        "ConvertRarityControl", "ConvertSoundType", "ConvertStartLocPrio", "ConvertTexMapFlags",
        "ConvertUnitEvent", "ConvertUnitState", "ConvertUnitType", "ConvertVersion", "ConvertVolumeGroup",
        "ConvertWeaponType", "ConvertWidgetEvent", "Cos", "Deg2Rad", "GetAbilityEffect",
        "GetAbilityEffectById", "GetAbilitySound", "GetAbilitySoundById", "GetAllyColorFilterState",
        "GetPlayerColor", "GetPlayerController", "GetPlayerId", "GetPlayerRace", "GetPlayerSelectable",
        "GetPlayerStartLocation", "GetPlayerTeam", "GetSoundDuration", "GetSoundFileDuration", "GetStartLocationLoc",
        "GetStartLocationX", "GetStartLocationY", "GetStartLocPrio", "GetStartLocPrioSlot", "GetSummonedUnit",
        "GetSummoningUnit", "GetTeams", "GetUnitDefaultAcquireRange",
        "GetUnitDefaultFlyHeight", "GetUnitDefaultMoveSpeed", "GetUnitDefaultPropWindow",
        "GetUnitDefaultTurnSpeed", "GetUnitName", "GetWinningPlayer", "GetWorldBounds", "I2R", "I2S",
        "Not", "Or", "OrderId", "OrderId2String", "Player", "Pow", "R2I",
        "R2S", "R2SW", "Rad2Deg", "S2I", "S2R", "Sin", "SquareRoot", "StringCase", "StringHash",
        "StringLength", "SubString", "Tan", "VersionGet", "BlzBitOr", "BlzBitAnd", "BlzBitXor"
    );
}