/*
** thingdef_exp.cpp
**
** Expression parsing for DECORATE
**
**---------------------------------------------------------------------------
** Copyright 2005 Jan Cholasta
** Copyright 2005-2016 Christoph Oelckers
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
**    notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
**    notice, this list of conditions and the following disclaimer in the
**    documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
**    derived from this software without specific prior written permission.
** 4. When not used as part of ZDoom or a ZDoom derivative, this code will be
**    covered by the terms of the GNU General Public License as published by
**    the Free Software Foundation; either version 2 of the License, or (at
**    your option) any later version.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
*/

#include "actor.h"
#include "cmdlib.h"
#include "a_pickups.h"
#include "thingdef.h"
#include "backend/codegen.h"

FRandom pr_exrandom ("EX_Random");

static FxExpression *ParseRandom(FScanner &sc, FName identifier, PClassActor *cls);
static FxExpression *ParseRandomPick(FScanner &sc, FName identifier, PClassActor *cls);
static FxExpression *ParseRandom2(FScanner &sc, PClassActor *cls);
static FxExpression *ParseAbs(FScanner &sc, PClassActor *cls);
static FxExpression *ParseAtan2(FScanner &sc, FName identifier, PClassActor *cls);
static FxExpression *ParseMinMax(FScanner &sc, FName identifier, PClassActor *cls);
static FxExpression *ParseClamp(FScanner &sc, PClassActor *cls);

//
// ParseExpression
// [GRB] Parses an expression and stores it into Expression array
// It's worth mentioning that this is using C++ operator precedence
//

static FxExpression *ParseExpressionM (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionL (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionK (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionJ (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionI (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionH (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionG (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionF (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionE (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionD (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionC (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionB (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpressionA (FScanner &sc, PClassActor *cls);
static FxExpression *ParseExpression0 (FScanner &sc, PClassActor *cls);

FxExpression *ParseExpression (FScanner &sc, PClassActor *cls, PNamespace *spc)
{
	FxExpression *data = ParseExpressionM (sc, cls);

	if (spc)
	{
		PClassType *vmtype = nullptr == cls ? nullptr : cls->VMType;
		FCompileContext ctx(spc, vmtype, true);
		data = data->Resolve(ctx);
	}

	return data;
}

static FxExpression *ParseExpressionM (FScanner &sc, PClassActor *cls)
{
	FxExpression *base = ParseExpressionL (sc, cls);

	if (sc.CheckToken('?'))
	{
		FxExpression *truex = ParseExpressionM (sc, cls);
		sc.MustGetToken(':');
		FxExpression *falsex = ParseExpressionM (sc, cls);
		return new FxConditional(base, truex, falsex);
	}
	else if (sc.CheckToken('='))
	{
		FxExpression *right = ParseExpressionM(sc, cls);
		return new FxAssign(base, right);
	}
	else
	{
		FxBinary *exp;
		FxAssignSelf *left = new FxAssignSelf(sc);

		sc.GetToken();
		switch (sc.TokenType)
		{
		case TK_AddEq:
			exp = new FxAddSub('+', left, nullptr);
			break;

		case TK_SubEq:
			exp = new FxAddSub('-', left, nullptr);
			break;

		case TK_MulEq:
			exp = new FxMulDiv('*', left, nullptr);
			break;

		case TK_DivEq:
			exp = new FxMulDiv('/', left, nullptr);
			break;

		case TK_ModEq:
			exp = new FxMulDiv('%', left, nullptr);
			break;

		case TK_LShiftEq:
			exp = new FxShift(TK_LShift, left, nullptr);
			break;

		case TK_RShiftEq:
			exp = new FxShift(TK_RShift, left, nullptr);
			break;

		case TK_URShiftEq:
			exp = new FxShift(TK_URShift, left, nullptr);
			break;

		case TK_AndEq:
			exp = new FxBitOp('&', left, nullptr);
			break;

		case TK_XorEq:
			exp = new FxBitOp('^', left, nullptr);
			break;

		case TK_OrEq:
			exp = new FxBitOp('|', left, nullptr);
			break;

		default:
			sc.UnGet();
			delete left;
			return base;
		}

		exp->right = ParseExpressionM(sc, cls);

		FxAssign *ret = new FxAssign(base, exp, true);
		left->Assignment = ret;
		return ret;
	}
}

static FxExpression *ParseExpressionL (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionK (sc, cls);

	while (sc.CheckToken(TK_OrOr))
	{
		FxExpression *right = ParseExpressionK (sc, cls);
		tmp = new FxBinaryLogical(TK_OrOr, tmp, right);
	}
	return tmp;
}

static FxExpression *ParseExpressionK (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionJ (sc, cls);

	while (sc.CheckToken(TK_AndAnd))
	{
		FxExpression *right = ParseExpressionJ (sc, cls);
		tmp = new FxBinaryLogical(TK_AndAnd, tmp, right);
	}
	return tmp;
}

static FxExpression *ParseExpressionJ (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionI (sc, cls);

	while (sc.CheckToken('|'))
	{
		FxExpression *right = ParseExpressionI (sc, cls);
		tmp = new FxBitOp('|', tmp, right);
	}
	return tmp;
}

static FxExpression *ParseExpressionI (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionH (sc, cls);

	while (sc.CheckToken('^'))
	{
		FxExpression *right = ParseExpressionH (sc, cls);
		tmp = new FxBitOp('^', tmp, right);
	}
	return tmp;
}

static FxExpression *ParseExpressionH (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionG (sc, cls);

	while (sc.CheckToken('&'))
	{
		FxExpression *right = ParseExpressionG (sc, cls);
		tmp = new FxBitOp('&', tmp, right);
	}
	return tmp;
}

static FxExpression *ParseExpressionG (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionF (sc, cls);

	while (sc.GetToken() && (sc.TokenType == TK_Eq || sc.TokenType == TK_Neq))
	{
		int token = sc.TokenType;
		FxExpression *right = ParseExpressionF (sc, cls);
		tmp = new FxCompareEq(token, tmp, right);
	}
	if (!sc.End) sc.UnGet();
	return tmp;
}

static FxExpression *ParseExpressionF (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionE (sc, cls);

	while (sc.GetToken() && (sc.TokenType == '<' || sc.TokenType == '>' || sc.TokenType == TK_Leq || sc.TokenType == TK_Geq))
	{
		int token = sc.TokenType;
		FxExpression *right = ParseExpressionE (sc, cls);
		tmp = new FxCompareRel(token, tmp, right);
	}
	if (!sc.End) sc.UnGet();
	return tmp;
}

static FxExpression *ParseExpressionE (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionD (sc, cls);

	while (sc.GetToken() && (sc.TokenType == TK_LShift || sc.TokenType == TK_RShift || sc.TokenType == TK_URShift))
	{
		int token = sc.TokenType;
		FxExpression *right = ParseExpressionD (sc, cls);
		tmp = new FxShift(token, tmp, right);
	}
	if (!sc.End) sc.UnGet();
	return tmp;
}

static FxExpression *ParseExpressionD (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionC (sc, cls);

	while (sc.GetToken() && (sc.TokenType == '+' || sc.TokenType == '-'))
	{
		int token = sc.TokenType;
		FxExpression *right = ParseExpressionC (sc, cls);
		tmp = new FxAddSub(token, tmp, right);
	}
	if (!sc.End) sc.UnGet();
	return tmp;
}

static FxExpression *ParseExpressionC (FScanner &sc, PClassActor *cls)
{
	FxExpression *tmp = ParseExpressionB (sc, cls);

	while (sc.GetToken() && (sc.TokenType == '*' || sc.TokenType == '/' || sc.TokenType == '%'))
	{
		int token = sc.TokenType;
		FxExpression *right = ParseExpressionB (sc, cls);
		tmp = new FxMulDiv(token, tmp, right);
	}
	if (!sc.End) sc.UnGet();
	return tmp;
}

static FxExpression *ParseExpressionB (FScanner &sc, PClassActor *cls)
{
	sc.GetToken();
	int token = sc.TokenType;
	switch(token)
	{
	case '~':
		return new FxUnaryNotBitwise(ParseExpressionA (sc, cls));

	case '!':
		return new FxUnaryNotBoolean(ParseExpressionA (sc, cls));

	case '-':
		return new FxMinusSign(ParseExpressionA (sc, cls));

	case '+':
		return new FxPlusSign(ParseExpressionA (sc, cls));

	case TK_Incr:
	case TK_Decr:
		return new FxPreIncrDecr(ParseExpressionA(sc, cls), token);

	default:
		sc.UnGet();
		return ParseExpressionA (sc, cls);
	}
}

//==========================================================================
//
//	ParseExpressionB
//
//==========================================================================

static FxExpression *ParseExpressionA (FScanner &sc, PClassActor *cls)
{
	FxExpression *base_expr = ParseExpression0 (sc, cls);

	while(1)
	{
		FScriptPosition pos(sc);

#if 0
		if (sc.CheckToken('.'))
		{
			if (sc.CheckToken(TK_Default))
			{
				sc.MustGetToken('.');
				base_expr = new FxClassDefaults(base_expr, pos);
			}
			sc.MustGetToken(TK_Identifier);

			FName FieldName = sc.String;
			pos = sc;
			/* later!
			if (SC_CheckToken('('))
			{
				if (base_expr->IsDefaultObject())
				{
					SC_ScriptError("Cannot call methods for default.");
				}
				base_expr = ParseFunctionCall(base_expr, FieldName, false, false, pos);
			}
			else
			*/
			{
				base_expr = new FxDotIdentifier(base_expr, FieldName, pos);
			}
		}
		else 
#endif
			if (sc.CheckToken('['))
		{
			FxExpression *index = ParseExpressionM(sc, cls);
			sc.MustGetToken(']');
			base_expr = new FxArrayElement(base_expr, index);
		}
		else if (sc.CheckToken(TK_Incr))
		{
			return new FxPostIncrDecr(base_expr, TK_Incr);
		}
		else if (sc.CheckToken(TK_Decr))
		{
			return new FxPostIncrDecr(base_expr, TK_Decr);
		}
		else break;
	} 

	return base_expr;
}



static FxExpression *ParseExpression0 (FScanner &sc, PClassActor *cls)
{
	FScriptPosition scpos(sc);
	if (sc.CheckToken('('))
	{
		FxExpression *data = ParseExpressionM (sc, cls);
		sc.MustGetToken(')');
		return data;
	}
	else if (sc.CheckToken(TK_True))
	{
		return new FxConstant(true, scpos);
	}
	else if (sc.CheckToken(TK_False))
	{
		return new FxConstant(false, scpos);
	}
	else if (sc.CheckToken(TK_IntConst))
	{
		return new FxConstant(sc.Number, scpos);
	}
	else if (sc.CheckToken(TK_FloatConst))
	{
		return new FxConstant(sc.Float, scpos);
	}
	else if (sc.CheckToken(TK_NameConst))
	{
		return new FxConstant(FName(sc.String), scpos);
	}
	else if (sc.CheckToken(TK_StringConst))
	{
		// String parameters are converted to names. Technically, this should be
		// done at a higher level, as needed, but since no functions take string
		// arguments and ACS_NamedExecuteWithResult/CallACS need names, this is
		// a cheap way to get them working when people use "name" instead of 'name'.
		return new FxConstant(FName(sc.String), scpos);
	}
	else if (sc.CheckToken(TK_Bool))
	{
		sc.MustGetToken('(');
		FxExpression *exp = ParseExpressionM(sc, cls);
		sc.MustGetToken(')');
		return new FxBoolCast(exp);
	}
	else if (sc.CheckToken(TK_Int))
	{
		sc.MustGetToken('(');
		FxExpression *exp = ParseExpressionM(sc, cls);
		sc.MustGetToken(')');
		return new FxIntCast(exp, true);
	}
	else if (sc.CheckToken(TK_Float))
	{
		sc.MustGetToken('(');
		FxExpression *exp = ParseExpressionM(sc, cls);
		sc.MustGetToken(')');
		return new FxFloatCast(exp);
	}
	else if (sc.CheckToken(TK_State))
	{
		sc.MustGetToken('(');
		FxExpression *exp;
		if (sc.CheckToken(TK_StringConst))
		{
			if (sc.String[0] == 0 || sc.Compare("None"))
			{
				exp = new FxConstant((FState*)nullptr, sc);
			}
			else
			{
				exp = new FxMultiNameState(sc.String, sc);
			}
		}
		else
		{
			exp = new FxRuntimeStateIndex(ParseExpressionM(sc, cls));
		}
		// The parsed expression is of type 'statelabel', but we want a real state here so we must convert it.
		if (!exp->isConstant())
		{
			FArgumentList args;
			args.Push(exp);
			exp = new FxFunctionCall(NAME_ResolveState, NAME_None, args, sc);
		}
		sc.MustGetToken(')');
		return exp;
	}
	else if (sc.CheckToken(TK_Identifier))
	{
		FName identifier = FName(sc.String);
		PFunction *func;

		switch (identifier)
		{
		case NAME_Random:
		case NAME_FRandom:
			return ParseRandom(sc, identifier, cls);
		case NAME_RandomPick:
		case NAME_FRandomPick:
			return ParseRandomPick(sc, identifier, cls);
		case NAME_Random2:
			return ParseRandom2(sc, cls);
		default:
			if (cls != nullptr)
			{
				func = dyn_cast<PFunction>(cls->FindSymbol(identifier, true));

				// There is an action function ACS_NamedExecuteWithResult which must be ignored here for this to work.
				if (func != nullptr && identifier != NAME_ACS_NamedExecuteWithResult)
				{
					FArgumentList args;
					if (sc.CheckToken('('))
					{
						sc.UnGet();
						ParseFunctionParameters(sc, cls, args, func, "", nullptr);
					}
					return new FxVMFunctionCall(new FxSelf(sc), func, args, sc, false);
				}
			}

			break;
		}
		if (sc.CheckToken('('))
		{
			switch (identifier)
			{
			case NAME_Min:
			case NAME_Max:
				return ParseMinMax(sc, identifier, cls);
			case NAME_Clamp:
				return ParseClamp(sc, cls);
			case NAME_Abs:
				return ParseAbs(sc, cls);
			case NAME_ATan2:
			case NAME_VectorAngle:
				return ParseAtan2(sc, identifier, cls);
			default:
				FArgumentList args;
				if (!sc.CheckToken(')'))
				{
					do
					{
						args.Push(ParseExpressionM (sc, cls));
					}
					while (sc.CheckToken(','));
					sc.MustGetToken(')');
				}
				return new FxFunctionCall(identifier, NAME_None, args, sc);
			}
		}
		else
		{
			return new FxIdentifier(identifier, sc);
		}
	}
	else
	{
		FString tokname = sc.TokenName(sc.TokenType, sc.String);
		sc.ScriptError ("Unexpected token %s", tokname.GetChars());
	}
	return NULL;
}

static FRandom *ParseRNG(FScanner &sc)
{
	FRandom *rng;

	if (sc.CheckToken('['))
	{
		sc.MustGetToken(TK_Identifier);
		rng = FRandom::StaticFindRNG(sc.String);
		sc.MustGetToken(']');
	}
	else
	{
		rng = &pr_exrandom;
	}
	return rng;
}

static FxExpression *ParseRandom(FScanner &sc, FName identifier, PClassActor *cls)
{
	FRandom *rng = ParseRNG(sc);

	sc.MustGetToken('(');
	FxExpression *min = ParseExpressionM (sc, cls);
	sc.MustGetToken(',');
	FxExpression *max = ParseExpressionM (sc, cls);
	sc.MustGetToken(')');

	if (identifier == NAME_Random)
	{
		return new FxRandom(rng, min, max, sc, true);
	}
	else
	{
		return new FxFRandom(rng, min, max, sc);
	}
}

static FxExpression *ParseRandomPick(FScanner &sc, FName identifier, PClassActor *cls)
{
	bool floaty = identifier == NAME_FRandomPick;
	FRandom *rng;
	TArray<FxExpression*> list;
	list.Clear();
	int index = 0;

	rng = ParseRNG(sc);
	sc.MustGetToken('(');

	for (;;)
	{
		FxExpression *expr = ParseExpressionM(sc, cls);
		list.Push(expr);
		if (sc.CheckToken(')'))
			break;
		sc.MustGetToken(',');
	}
	return new FxRandomPick(rng, list, floaty, sc, true);
}

static FxExpression *ParseRandom2(FScanner &sc, PClassActor *cls)
{
	FRandom *rng = ParseRNG(sc);
	FxExpression *mask = NULL;

	sc.MustGetToken('(');

	if (!sc.CheckToken(')'))
	{
		mask = ParseExpressionM(sc, cls);
		sc.MustGetToken(')');
	}
	return new FxRandom2(rng, mask, sc, true);
}

static FxExpression *ParseAbs(FScanner &sc, PClassActor *cls)
{
	FxExpression *x = ParseExpressionM (sc, cls);
	sc.MustGetToken(')');
	return new FxAbs(x); 
}

static FxExpression *ParseAtan2(FScanner &sc, FName identifier, PClassActor *cls)
{
	FxExpression *a = ParseExpressionM(sc, cls);
	sc.MustGetToken(',');
	FxExpression *b = ParseExpressionM(sc, cls);
	sc.MustGetToken(')');
	return identifier == NAME_ATan2 ? new FxATan2(a, b, sc) : new FxATan2(b, a, sc);
}

static FxExpression *ParseMinMax(FScanner &sc, FName identifier, PClassActor *cls)
{
	TArray<FxExpression*> list;
	for (;;)
	{
		FxExpression *expr = ParseExpressionM(sc, cls);
		list.Push(expr);
		if (sc.CheckToken(')'))
			break;
		sc.MustGetToken(',');
	}
	return new FxMinMax(list, identifier, sc);
}

static FxExpression *ParseClamp(FScanner &sc, PClassActor *cls)
{
	FxExpression *src = ParseExpressionM(sc, cls);
	sc.MustGetToken(',');
	FxExpression *min = ParseExpressionM(sc, cls);
	sc.MustGetToken(',');
	FxExpression *max = ParseExpressionM(sc, cls);
	sc.MustGetToken(')');

	// Build clamp(a,x,y) as min(max(a,x),y)
	TArray<FxExpression *> list(2);
	list.Reserve(2);
	list[0] = src;
	list[1] = min;
	FxExpression *maxexpr = new FxMinMax(list, NAME_Max, sc);
	list[0] = maxexpr;
	list[1] = max;
	return new FxMinMax(list, NAME_Min, sc);
}
