//
// Copyright 2019 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#include "compiler/translator/ValidateAST.h"

#include "compiler/translator/Diagnostics.h"
#include "compiler/translator/Symbol.h"
#include "compiler/translator/tree_util/IntermTraverse.h"
#include "compiler/translator/tree_util/SpecializationConstant.h"

namespace sh
{

namespace
{

class ValidateAST : public TIntermTraverser
{
  public:
    static bool validate(TIntermNode *root,
                         TDiagnostics *diagnostics,
                         const ValidateASTOptions &options);

    void visitSymbol(TIntermSymbol *node) override;
    void visitConstantUnion(TIntermConstantUnion *node) override;
    bool visitSwizzle(Visit visit, TIntermSwizzle *node) override;
    bool visitBinary(Visit visit, TIntermBinary *node) override;
    bool visitUnary(Visit visit, TIntermUnary *node) override;
    bool visitTernary(Visit visit, TIntermTernary *node) override;
    bool visitIfElse(Visit visit, TIntermIfElse *node) override;
    bool visitSwitch(Visit visit, TIntermSwitch *node) override;
    bool visitCase(Visit visit, TIntermCase *node) override;
    void visitFunctionPrototype(TIntermFunctionPrototype *node) override;
    bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node) override;
    bool visitAggregate(Visit visit, TIntermAggregate *node) override;
    bool visitBlock(Visit visit, TIntermBlock *node) override;
    bool visitGlobalQualifierDeclaration(Visit visit,
                                         TIntermGlobalQualifierDeclaration *node) override;
    bool visitDeclaration(Visit visit, TIntermDeclaration *node) override;
    bool visitLoop(Visit visit, TIntermLoop *node) override;
    bool visitBranch(Visit visit, TIntermBranch *node) override;
    void visitPreprocessorDirective(TIntermPreprocessorDirective *node) override;

  private:
    ValidateAST(TIntermNode *root, TDiagnostics *diagnostics, const ValidateASTOptions &options);

    // Visit as a generic node
    void visitNode(Visit visit, TIntermNode *node);
    // Visit a structure or interface block, and recursively visit its fields of structure type.
    void visitStructOrInterfaceBlockDeclaration(const TType &type, const TSourceLoc &location);
    void visitStructInDeclarationUsage(const TType &type, const TSourceLoc &location);

    void scope(Visit visit);
    bool isVariableDeclared(const TVariable *variable);
    bool variableNeedsDeclaration(const TVariable *variable);
    const TFieldListCollection *getStructOrInterfaceBlock(const TType &type,
                                                          ImmutableString *typeNameOut);

    void expectNonNullChildren(Visit visit, TIntermNode *node, size_t least_count);

    bool validateInternal();

    ValidateASTOptions mOptions;
    TDiagnostics *mDiagnostics;

    // For validateSingleParent:
    std::map<TIntermNode *, TIntermNode *> mParent;
    bool mSingleParentFailed = false;

    // For validateVariableReferences:
    std::vector<std::set<const TVariable *>> mDeclaredVariables;
    std::set<const TInterfaceBlock *> mNamelessInterfaceBlocks;
    bool mVariableReferencesFailed = false;

    // For validateNullNodes:
    bool mNullNodesFailed = false;

    // For validateStructUsage:
    std::vector<std::map<ImmutableString, const TFieldListCollection *>> mStructsAndBlocksByName;
    bool mStructUsageFailed = false;

    // For validateMultiDeclarations:
    bool mMultiDeclarationsFailed = false;
};

bool ValidateAST::validate(TIntermNode *root,
                           TDiagnostics *diagnostics,
                           const ValidateASTOptions &options)
{
    ValidateAST validate(root, diagnostics, options);
    root->traverse(&validate);
    return validate.validateInternal();
}

ValidateAST::ValidateAST(TIntermNode *root,
                         TDiagnostics *diagnostics,
                         const ValidateASTOptions &options)
    : TIntermTraverser(true, false, true, nullptr), mOptions(options), mDiagnostics(diagnostics)
{
    bool isTreeRoot = root->getAsBlock() && root->getAsBlock()->isTreeRoot();

    // Some validations are not applicable unless run on the entire tree.
    if (!isTreeRoot)
    {
        mOptions.validateVariableReferences = false;
    }

    if (mOptions.validateSingleParent)
    {
        mParent[root] = nullptr;
    }
}

void ValidateAST::visitNode(Visit visit, TIntermNode *node)
{
    if (visit == PreVisit && mOptions.validateSingleParent)
    {
        size_t childCount = node->getChildCount();
        for (size_t i = 0; i < childCount; ++i)
        {
            TIntermNode *child = node->getChildNode(i);
            if (mParent.find(child) != mParent.end())
            {
                // If child is visited twice but through the same parent, the problem is in one of
                // the ancestors.
                if (mParent[child] != node)
                {
                    mDiagnostics->error(node->getLine(), "Found child with two parents",
                                        "<validateSingleParent>");
                    mSingleParentFailed = true;
                }
            }

            mParent[child] = node;
        }
    }
}

void ValidateAST::visitStructOrInterfaceBlockDeclaration(const TType &type,
                                                         const TSourceLoc &location)
{
    if (type.getStruct() == nullptr && type.getInterfaceBlock() == nullptr)
    {
        return;
    }

    // Make sure the structure or interface block is not doubly defined.
    ImmutableString typeName("");
    const TFieldListCollection *structOrBlock = getStructOrInterfaceBlock(type, &typeName);

    if (structOrBlock)
    {
        ASSERT(!typeName.empty());

        if (mStructsAndBlocksByName.back().find(typeName) != mStructsAndBlocksByName.back().end())
        {
            mDiagnostics->error(location,
                                "Found redeclaration of struct or interface block with the same "
                                "name in the same scope <validateStructUsage>",
                                typeName.data());
            mStructUsageFailed = true;
        }
        else
        {
            // First encounter.
            mStructsAndBlocksByName.back()[typeName] = structOrBlock;
        }
    }

    // Recurse the fields of the structure or interface block and check members of structure type.
    // Note that structOrBlock was previously only set for named structures, so make sure nameless
    // structs are also recursed.
    if (structOrBlock == nullptr)
    {
        structOrBlock = type.getStruct();
    }
    ASSERT(structOrBlock != nullptr);

    for (const TField *field : structOrBlock->fields())
    {
        visitStructInDeclarationUsage(*field->type(), field->line());
    }
}

void ValidateAST::visitStructInDeclarationUsage(const TType &type, const TSourceLoc &location)
{
    if (type.getStruct() == nullptr)
    {
        return;
    }

    // Make sure the structure being referenced has the same pointer as the closest (in scope)
    // definition.
    const TStructure *structure     = type.getStruct();
    const ImmutableString &typeName = structure->name();

    bool foundDeclaration = false;
    for (size_t scopeIndex = mStructsAndBlocksByName.size(); scopeIndex > 0; --scopeIndex)
    {
        const std::map<ImmutableString, const TFieldListCollection *> &scopeDecls =
            mStructsAndBlocksByName[scopeIndex - 1];

        auto iter = scopeDecls.find(typeName);
        if (iter != scopeDecls.end())
        {
            foundDeclaration = true;

            if (iter->second != structure)
            {
                mDiagnostics->error(location,
                                    "Found reference to struct or interface block with doubly "
                                    "created type <validateStructUsage>",
                                    typeName.data());
                mStructUsageFailed = true;
            }
        }
    }

    if (!foundDeclaration)
    {
        mDiagnostics->error(location,
                            "Found reference to struct or interface block with no declaration "
                            "<validateStructUsage>",
                            typeName.data());
        mStructUsageFailed = true;
    }
}

void ValidateAST::scope(Visit visit)
{
    if (mOptions.validateVariableReferences)
    {
        if (visit == PreVisit)
        {
            mDeclaredVariables.push_back({});
        }
        else if (visit == PostVisit)
        {
            mDeclaredVariables.pop_back();
        }
    }

    if (mOptions.validateStructUsage)
    {
        if (visit == PreVisit)
        {
            mStructsAndBlocksByName.push_back({});
        }
        else if (visit == PostVisit)
        {
            mStructsAndBlocksByName.pop_back();
        }
    }
}

bool ValidateAST::isVariableDeclared(const TVariable *variable)
{
    ASSERT(mOptions.validateVariableReferences);

    for (const std::set<const TVariable *> &scopeVariables : mDeclaredVariables)
    {
        if (scopeVariables.count(variable) > 0)
        {
            return true;
        }
    }

    return false;
}

bool ValidateAST::variableNeedsDeclaration(const TVariable *variable)
{
    // Don't expect declaration for built-in variables.
    if (variable->name().beginsWith("gl_"))
    {
        return false;
    }

    // Additionally, don't expect declaration for Vulkan specialization constants.  There is no
    // representation for them in the AST.
    if (variable->symbolType() == SymbolType::AngleInternal &&
        SpecConst::IsSpecConstName(variable->name()))
    {
        return false;
    }

    return true;
}

const TFieldListCollection *ValidateAST::getStructOrInterfaceBlock(const TType &type,
                                                                   ImmutableString *typeNameOut)
{
    const TStructure *structure           = type.getStruct();
    const TInterfaceBlock *interfaceBlock = type.getInterfaceBlock();

    ASSERT(structure != nullptr || interfaceBlock != nullptr);

    // Make sure the structure or interface block is not doubly defined.
    const TFieldListCollection *structOrBlock = nullptr;
    if (structure != nullptr && structure->symbolType() != SymbolType::Empty)
    {
        structOrBlock = structure;
        *typeNameOut  = structure->name();
    }
    else if (interfaceBlock != nullptr)
    {
        structOrBlock = interfaceBlock;
        *typeNameOut  = interfaceBlock->name();
    }

    return structOrBlock;
}

void ValidateAST::expectNonNullChildren(Visit visit, TIntermNode *node, size_t least_count)
{
    if (visit == PreVisit && mOptions.validateNullNodes)
    {
        size_t childCount = node->getChildCount();
        if (childCount < least_count)
        {
            mDiagnostics->error(node->getLine(), "Too few children", "<validateNullNodes>");
            mNullNodesFailed = true;
        }

        for (size_t i = 0; i < childCount; ++i)
        {
            if (node->getChildNode(i) == nullptr)
            {
                mDiagnostics->error(node->getLine(), "Found nullptr child", "<validateNullNodes>");
                mNullNodesFailed = true;
            }
        }
    }
}

void ValidateAST::visitSymbol(TIntermSymbol *node)
{
    visitNode(PreVisit, node);

    const TVariable *variable = &node->variable();
    const TType &type         = node->getType();

    if (mOptions.validateVariableReferences && variableNeedsDeclaration(variable))
    {
        // If it's a reference to a field of a nameless interface block, match it by index and name.
        if (type.getInterfaceBlock() && !type.isInterfaceBlock())
        {
            const TInterfaceBlock *interfaceBlock = type.getInterfaceBlock();
            const TFieldList &fieldList           = interfaceBlock->fields();
            const size_t fieldIndex               = type.getInterfaceBlockFieldIndex();

            if (mNamelessInterfaceBlocks.count(interfaceBlock) == 0)
            {
                mDiagnostics->error(node->getLine(),
                                    "Found reference to undeclared or inconsistenly redeclared "
                                    "nameless interface block <validateVariableReferences>",
                                    node->getName().data());
                mVariableReferencesFailed = true;
            }
            else if (fieldIndex >= fieldList.size() ||
                     node->getName() != fieldList[fieldIndex]->name())
            {
                mDiagnostics->error(node->getLine(),
                                    "Found reference to inconsistenly redeclared nameless "
                                    "interface block field <validateVariableReferences>",
                                    node->getName().data());
                mVariableReferencesFailed = true;
            }
        }
        else
        {
            const bool isStructDeclaration =
                type.isStructSpecifier() && variable->symbolType() == SymbolType::Empty;

            if (!isStructDeclaration && !isVariableDeclared(variable))
            {
                mDiagnostics->error(node->getLine(),
                                    "Found reference to undeclared or inconsistently redeclared "
                                    "variable <validateVariableReferences>",
                                    node->getName().data());
                mVariableReferencesFailed = true;
            }
        }
    }
}

void ValidateAST::visitConstantUnion(TIntermConstantUnion *node)
{
    visitNode(PreVisit, node);
}

bool ValidateAST::visitSwizzle(Visit visit, TIntermSwizzle *node)
{
    visitNode(visit, node);
    return true;
}

bool ValidateAST::visitBinary(Visit visit, TIntermBinary *node)
{
    visitNode(visit, node);
    return true;
}

bool ValidateAST::visitUnary(Visit visit, TIntermUnary *node)
{
    visitNode(visit, node);
    return true;
}

bool ValidateAST::visitTernary(Visit visit, TIntermTernary *node)
{
    visitNode(visit, node);
    return true;
}

bool ValidateAST::visitIfElse(Visit visit, TIntermIfElse *node)
{
    visitNode(visit, node);
    return true;
}

bool ValidateAST::visitSwitch(Visit visit, TIntermSwitch *node)
{
    visitNode(visit, node);
    return true;
}

bool ValidateAST::visitCase(Visit visit, TIntermCase *node)
{
    visitNode(visit, node);
    return true;
}

void ValidateAST::visitFunctionPrototype(TIntermFunctionPrototype *node)
{
    visitNode(PreVisit, node);
}

bool ValidateAST::visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node)
{
    visitNode(visit, node);
    scope(visit);

    if (mOptions.validateVariableReferences && visit == PreVisit)
    {
        const TFunction *function = node->getFunction();

        size_t paramCount = function->getParamCount();
        for (size_t paramIndex = 0; paramIndex < paramCount; ++paramIndex)
        {
            const TVariable *variable = function->getParam(paramIndex);

            if (isVariableDeclared(variable))
            {
                mDiagnostics->error(node->getLine(),
                                    "Found two declarations of the same function argument "
                                    "<validateVariableReferences>",
                                    variable->name().data());
                mVariableReferencesFailed = true;
                break;
            }

            mDeclaredVariables.back().insert(variable);
        }
    }

    return true;
}

bool ValidateAST::visitAggregate(Visit visit, TIntermAggregate *node)
{
    visitNode(visit, node);
    expectNonNullChildren(visit, node, 0);
    return true;
}

bool ValidateAST::visitBlock(Visit visit, TIntermBlock *node)
{
    visitNode(visit, node);
    scope(visit);
    expectNonNullChildren(visit, node, 0);
    return true;
}

bool ValidateAST::visitGlobalQualifierDeclaration(Visit visit,
                                                  TIntermGlobalQualifierDeclaration *node)
{
    visitNode(visit, node);

    const TVariable *variable = &node->getSymbol()->variable();

    if (mOptions.validateVariableReferences && variableNeedsDeclaration(variable))
    {
        if (!isVariableDeclared(variable))
        {
            mDiagnostics->error(node->getLine(),
                                "Found reference to undeclared or inconsistently redeclared "
                                "variable <validateVariableReferences>",
                                variable->name().data());
            mVariableReferencesFailed = true;
        }
    }
    return true;
}

bool ValidateAST::visitDeclaration(Visit visit, TIntermDeclaration *node)
{
    visitNode(visit, node);
    expectNonNullChildren(visit, node, 0);

    const TIntermSequence &sequence = *(node->getSequence());

    if (mOptions.validateMultiDeclarations && sequence.size() > 1)
    {
        mMultiDeclarationsFailed = true;
    }

    if (visit == PreVisit)
    {
        bool validateStructUsage = mOptions.validateStructUsage;

        for (TIntermNode *instance : sequence)
        {
            TIntermSymbol *symbol = instance->getAsSymbolNode();
            if (symbol == nullptr)
            {
                TIntermBinary *init = instance->getAsBinaryNode();
                ASSERT(init && init->getOp() == EOpInitialize);
                symbol = init->getLeft()->getAsSymbolNode();
            }
            ASSERT(symbol);

            const TVariable *variable = &symbol->variable();

            if (mOptions.validateVariableReferences)
            {
                if (isVariableDeclared(variable))
                {
                    mDiagnostics->error(
                        node->getLine(),
                        "Found two declarations of the same variable <validateVariableReferences>",
                        variable->name().data());
                    mVariableReferencesFailed = true;
                    break;
                }

                mDeclaredVariables.back().insert(variable);

                const TInterfaceBlock *interfaceBlock = variable->getType().getInterfaceBlock();

                if (variable->symbolType() == SymbolType::Empty && interfaceBlock != nullptr)
                {
                    // Nameless interface blocks can only be declared at the top level.  Their
                    // fields are matched by field index, and then verified to match by name.
                    // Conflict in names should have already generated a compile error.
                    ASSERT(mDeclaredVariables.size() == 1);
                    ASSERT(mNamelessInterfaceBlocks.count(interfaceBlock) == 0);

                    mNamelessInterfaceBlocks.insert(interfaceBlock);
                }
            }

            if (validateStructUsage)
            {
                // Only declare the struct once.
                validateStructUsage = false;

                const TType &type = variable->getType();
                if (type.isStructSpecifier() || type.isInterfaceBlock())
                    visitStructOrInterfaceBlockDeclaration(type, node->getLine());
            }
        }
    }

    return true;
}

bool ValidateAST::visitLoop(Visit visit, TIntermLoop *node)
{
    visitNode(visit, node);
    return true;
}

bool ValidateAST::visitBranch(Visit visit, TIntermBranch *node)
{
    visitNode(visit, node);
    return true;
}

void ValidateAST::visitPreprocessorDirective(TIntermPreprocessorDirective *node)
{
    visitNode(PreVisit, node);
}

bool ValidateAST::validateInternal()
{
    return !mSingleParentFailed && !mVariableReferencesFailed && !mNullNodesFailed &&
           !mStructUsageFailed && !mMultiDeclarationsFailed;
}

}  // anonymous namespace

bool ValidateAST(TIntermNode *root, TDiagnostics *diagnostics, const ValidateASTOptions &options)
{
    return ValidateAST::validate(root, diagnostics, options);
}

}  // namespace sh
