/* vim: set ts=4 sw=4 tw=99 et:

 *

 * Copyright (C) 2012 David Anderson

 *

 * This file is part of SourcePawn.

 *

 * SourcePawn is free software: you can redistribute it and/or modify it under

 * the terms of the GNU General Public License as published by the Free

 * Software Foundation, either version 3 of the License, or (at your option)

 * any later version.

 * 

 * SourcePawn is distributed in the hope that it will be useful, but WITHOUT ANY

 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License along with

 * SourcePawn. If not, see http://www.gnu.org/licenses/.

 */

#include <assert.h>

#include "../Zone.h"

#include "../Strings.h"

#include "../NativeTable.h"

#include "../TypeManager.h"

#include "../Modules.h"

#include "../Code.h"

#include "SemanticAnalysis.h"

#include "../Heap-inl.h"

using namespace ke;

#define __ emitter_.

typedef BytecodeEmitter::Label Label;

class AutoEnterScope

{

  public:

    AutoEnterScope(Scope **prevp, Scope *scope)

      : prevp_(prevp),

        prev_(*prevp),

        scope_(scope)

    {

        if (!scope_)

            return;

        prev_ = *prevp_;

        *prevp_ = scope;

        assert(prev_ == scope->enclosing());

    }

    ~AutoEnterScope()

    {

        if (scope_)

            *prevp_ = prev_;

    }

  private:

    Scope **prevp_;

    Scope *prev_;

    Scope *scope_;

};

SemanticAnalysis::SemanticAnalysis(Zone *zone, CompileContext &cc, TranslationUnit *unit)

  : zone_(zone),

    pool_(zone->pool()),

    cc_(cc),

    unit_(unit),

    hir_(NULL),

    emitter_(pool_),

    module_(NULL),

    loop_(NULL)

{

}

SemanticAnalysis::SemanticAnalysis(SemanticAnalysis *parent, Handle<FunctionType> fun)

  : zone_(parent->zone_),

    pool_(parent->pool_),

    cc_(parent->cc_),

    unit_(parent->unit_),

    hir_(NULL),

    scope_(parent->scope_),

    emitter_(pool_),

    module_(parent->module_),

    fun_(fun),

    loop_(NULL)

{

}

void

SemanticAnalysis::analyze()

{

    scope_ = unit_->globalScope();

    module_ = Module::New(zone_);

    for (size_t i = 0; i < unit_->tree()->statements()->length(); i++) {

        Statement *stmt = unit_->tree()->statements()->at(i);

        stmt->accept(this);

    }

    Local<Struct> globals(zone_, unit_->globalScope()->build(zone_));

    if (!globals)

        return;

    module_->setGlobals(globals);

    Local<Code> code(zone_, __ finish());

    if (!code)

        return;

    code->setModule(module_);

    module_->setCode(code);

#ifndef NDEBUG

//    Disassemble(code, stdout);

#endif

    unit_->module_ = module_;

}

void

SemanticAnalysis::visitFunctionStatement(FunctionStatement *stmt)

{

    FunctionSymbol *sym = stmt->sym();

    Local<FunctionType> type(zone_, sym->type());

    assert(scope_->kind() == Scope::GLOBAL);

    if (stmt->token() == TOK_NATIVE) {

        // Define the native now.

        size_t index;

        if (!zone_->nativeTable()->add(stmt->name(), &index))

            return;

        Local<Native> native(zone_, Native::New(zone_, type, index));

        if (!native)

            return;

        __ object(native);

        __ setglobal(sym);

        __ pop();

    }

    // If the function is a forward or native, we don't have to do anything.

    if (stmt->token() == TOK_NATIVE || stmt->token() == TOK_FORWARD)

        return;

    SemanticAnalysis child(this, type);

    Local<Function> funobj(zone_, child.compile(stmt));

    if (!funobj)

        return;

    __ object(funobj);

    __ setglobal(sym);

    __ public_();

}

Function *

SemanticAnalysis::compile(FunctionStatement *stmt)

{

    __ setFirstLine(stmt->pos().line);

    AutoEnterScope argScope(&scope_, stmt->argScope());

    AutoEnterScope varScope(&scope_, stmt->varScope());

    stmt->body()->accept(this);

    Local<Code> code(zone_, __ finish());

    if (!code)

        return NULL;

    code->setModule(module_);

    Local<Function> fun(zone_, Function::New(zone_, code, fun_, stmt->name(), stmt->pos()));

    if (!fun)

        return NULL;

#ifndef NDEBUG

//    Disassemble(code, stdout);

#endif

    return fun;

}

void 

SemanticAnalysis::visitBlockStatement(BlockStatement *node)

{

    AutoEnterScope scope(&scope_, node->scope());

    for (size_t i = 0; i < node->statements()->length(); i++) {

        Statement *stmt = node->statements()->at(i);

        stmt->accept(this);

        assert(__ stackDepth() == 0);

    }

}

void

SemanticAnalysis::visitExpressionStatement(ExpressionStatement *node)

{

    // While building HIR, we enter new pool and root scopes, since HIR

    // creation is purely temporary.

    PoolScope poolScope(zone_->pool());

    RootScope rootScope(zone_);

    HIR *hir = eval(node->expression());

    if (!hir)

        return;

    discharge(hir);

    __ pop();

}

void

SemanticAnalysis::visitForStatement(ForStatement *node)

{

    AutoEnterScope scope(&scope_, node->scope());

    PoolScope poolScope(zone_->pool());

    RootScope rootScope(zone_);

    Label join, update;

    LoopScope loop(scope_, &join, &update, &loop_);

    if (node->initialization())

        node->initialization()->accept(this);

    Label header, test;

    if (node->condition())

        __ jump(&test);

    __ bind(&header);

    node->body()->accept(this);

    __ bind(&update);

    if (node->update())

        node->update()->accept(this);

    if (node->condition()) {

        __ bind(&test);

        visitForTest(node->condition(), &header, &join, &join);

    } else {

        __ jump(&header);

    }

    __ bind(&join);

    assert(__ stackDepth() == 0);

}

void

SemanticAnalysis::visitVariableDeclaration(VariableDeclaration *node)

{

    PoolScope poolScope(zone_->pool());

    RootScope rootScope(zone_);

    HIR *hir = NULL;

    if (node->initialization()) {

        if ((hir = eval(node->initialization())) == NULL)

            return;

        if ((hir = coerce(hir, node->sym()->type(), Coerce_Assign)) == NULL)

            return;

    } else {

        assert(false);

    }

    discharge(hir);

    if (!__ allocate(node->sym()))

        return;

    set(node->sym());

    __ pop();

}

void

SemanticAnalysis::visitReturnStatement(ReturnStatement *node)

{

    if (!node->expression()) {

        if (!fun_->returnType()->isVoid()) {

            cc_.reportError(node->pos(), Message_UsedVoidReturn);

            return;

        }

        __ returnvoid();

        return;

    }

    PoolScope poolScope(zone_->pool());

    RootScope rootScope(zone_);

    HIR *hir = eval(node->expression());

    if (!hir)

        return;

    Local<Type> returnType(zone_, fun_->returnType());

    if ((hir = coerce(hir, returnType, Coerce_Return)) == NULL)

        return;

    discharge(hir);

    __ return_();

}

void

SemanticAnalysis::visitBinaryExpression(BinaryExpression *node)

{

    HIR *left = eval(node->left());

    HIR *right = eval(node->right());

    if (!left || !right)

        return;

    hir_ = binary(node->token(), left, right);

}

bool

SemanticAnalysis::checkArgumentCount(Handle<FunctionType> type, unsigned actual)

{

    if (type->parameters()->length() == actual)

        return true;

    if (actual > type->parameters()->length()) {

        if (!type->isNative() || !type->isNativeVariadic())

            return false;

        return true;

    }

    if (!type->defaults())

        return false;

    // Missing arguments. See if there's a default argument for each missing

    // actual.

    for (unsigned i = actual; i < type->parameters()->length(); i++) {

        if (!type->defaults()->at(i))

            return false;

    }

    return true;

}

void

SemanticAnalysis::visitNameProxy(NameProxy *proxy)

{

    Symbol *sym = proxy->sym();

    Handle<Type> type = sym->type();

    VariableSymbol *var = sym->asVariable();

    Scope *in = sym->scope();

    switch (in->kind()) {

      case Scope::GLOBAL:

        hir_ = new (pool_) HGlobal(sym);

        return;

      default:

        assert(in->kind() == Scope::BLOCK);

        assert(var->storage() == VariableSymbol::Local);

        hir_ = new (pool_) HLocal(var);

        return;

    }

}

void

SemanticAnalysis::visitIntegerLiteral(IntegerLiteral *lit)

{

    Local<Type> type(zone_, zone_->types()->getPrimitive(PrimitiveType_Int32));

    hir_ = new (pool_) HInteger(type, lit->value());

}

void

SemanticAnalysis::visitFloatLiteral(FloatLiteral *node)

{

    Local<Type> type(zone_, zone_->types()->getPrimitive(PrimitiveType_Float));

    hir_ = new (pool_) HFloat(type, (float)node->value());

}

void

SemanticAnalysis::visitCallExpression(CallExpression *node)

{

    HIR *callee = eval(node->callee());

    if (!callee)

        return;

    if (!callee->type()->isFunction()) {

        cc_.reportError(node->pos(), Message_CalleeNotFunction);

        return;

    }

    Local<FunctionType> fun(zone_, FunctionType::cast(callee->type()));

    if (!checkArgumentCount(fun, node->arguments()->length())) {

        cc_.reportError(node->pos(), Message_ArgumentCountMismatch);

        return;

    }

    if (fun->isForward()) {

        cc_.reportError(node->pos(), Message_ForwardNotImplemented, fun->name()->chars());

        return;

    }

    HIRList *args = new (pool_) HIRList;

    for (unsigned i = 0; i < node->arguments()->length(); i++) {

        Expression *expression = node->arguments()->at(i);

        HIR *arg = eval(expression);

        if (!arg)

            return;

        Handle<Type> given = arg->type();

        bool mustComputeReference;

        if (i >= fun->parameters()->length()) {

            // Special handling for natives. Arguments past the formal must

            // always have references computed. However, arrays are already

            // references for natives.

            assert(fun->isNative() && fun->isNativeVariadic());

            mustComputeReference = !given->isReference() &&

                                   !given->isArray();

        } else {

            Local<Type> actual(zone_, fun->parameterAt(i));

            if (expression->isIndexExpression()) {

                // Temporarily disabled.

                assert(!actual->isArray());

                if (actual->isReference()) {

                    cc_.reportError(expression->pos(), Message_CannotComputeIndexRef);

                    return;

                }

            }

            // When we start overloading, coercion will have to happen later.

            arg = coerce(arg, actual, Coerce_Arg);

            if (!arg)

                return;

            mustComputeReference = actual->isReference() && !given->isReference();

        }

        // :TODO: handle mustComputeReference

        assert(!mustComputeReference);

        if (!args->append(arg))

            return;

    }

    hir_ = new (pool_) HCall(fun->returnType(), callee, args);

}

void

SemanticAnalysis::visitAssignment(Assignment *node)

{

    HLValue *lval = lvalue(node->lvalue());

    if (!lval)

        return;

    HIR *hir = eval(node->expression());

    if ((hir = coerce(hir, lval->type(), Coerce_Assign)) == NULL)

        return;

    hir_ = new (pool_) HStore(lval, hir);

}

Type *

SemanticAnalysis::coercionType(TokenKind token, HIR *left, HIR *right)

{

    Handle<Type> l = left->type();

    Handle<Type> r = right->type();

    if (token >= TOK_PLUS && token <= TOK_SLASH) {

        // We allow: [float|int32] + [float|int32]

        if (l->isFloat() && r->isInt32())

            return l;

        if (l->isInt32() && r->isFloat())

            return r;

        if (l->isInt32() && r->isInt32())

            return l;

    }

    assert(l == r);

    return left->type();

}

HIR *

SemanticAnalysis::coerce(HIR *hir, Handle<Type> to, CoercionKind kind)

{

    Handle<Type> from = hir->type();

    if (from->isInt32() && to->isFloat())

        return new (pool_) HConvert(to, OP_CVT_I2F, hir);

    assert(from == to);

    return hir;

}

void

SemanticAnalysis::set(VariableSymbol *sym)

{

    if (sym->scope()->kind() == Scope::GLOBAL) {

        __ setglobal(sym);

    } else {

        assert(sym->storage() == VariableSymbol::Local);

        __ setlocal(sym);

    }

}

HIR *

SemanticAnalysis::binary(TokenKind token, HIR *left, HIR *right)

{

    Local<Type> coercion(zone_, coercionType(token, left, right));

    if (!coercion)

        return NULL;

    if ((left = coerce(left, coercion, Coerce_Arg)) == NULL)

        return NULL;

    if ((right = coerce(right, coercion, Coerce_Arg)) == NULL)

        return NULL;

    switch (token) {

     case TOK_PLUS:

      case TOK_MINUS:

      case TOK_STAR:

      case TOK_SLASH:

      case TOK_PERCENT:

      case TOK_AMPERSAND:

      case TOK_BITOR:

      case TOK_BITXOR:

      case TOK_SHR:

      case TOK_USHR:

      case TOK_SHL:

        return new (pool_) HBinary(left->type(), token, left, right);

      case TOK_EQUALS:

      case TOK_NOTEQUALS:

      case TOK_LT:

      case TOK_LE:

      case TOK_GT:

      case TOK_GE:

      case TOK_AND:

      case TOK_OR:

      {

        Local<Type> result(zone_, zone_->types()->getPrimitive(PrimitiveType_Bool));

        return new (pool_) HBinary(result, token, left, right);

      }

      default:

        assert(false);

        return NULL;

    }

}

static inline TokenKind

ToCompare(Expression *expr)

{

    if (expr->isBinaryExpression()) {

        BinaryExpression *b = expr->toBinaryExpression();

        if (b->token() >= TOK_EQUALS && b->token() <= TOK_OR)

            return b->token();

    } else if (expr->isUnaryExpression()) {

        UnaryExpression *u = expr->toUnaryExpression();

        if (u->token() == TOK_NOT)

            return TOK_NOT;

    }

    return TOK_EOF;

}

void

SemanticAnalysis::visitForTest(Expression *expr,

                               Label *trueBranch,

                               Label *falseBranch,

                               Label *fallthrough)

{

    TokenKind token = ToCompare(expr);

    if (token == TOK_EOF || token == TOK_NOT) {