/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SKSL_CONSTRUCTOR
#define SKSL_CONSTRUCTOR

#include "SkSLExpression.h"
#include "SkSLFloatLiteral.h"
#include "SkSLIntLiteral.h"
#include "SkSLIRGenerator.h"

namespace SkSL {

/**
 * Represents the construction of a compound type, such as "vec2(x, y)".
 *
 * Vector constructors will always consist of either exactly 1 scalar, or a collection of vectors
 * and scalars totalling exactly the right number of scalar components.
 *
 * Matrix constructors will always consist of either exactly 1 scalar, exactly 1 matrix, or a
 * collection of vectors and scalars totalling exactly the right number of scalar components.
 */
struct Constructor : public Expression {
    Constructor(Position position, const Type& type,
                std::vector<std::unique_ptr<Expression>> arguments)
    : INHERITED(position, kConstructor_Kind, type)
    , fArguments(std::move(arguments)) {}

    std::unique_ptr<Expression> constantPropagate(const IRGenerator& irGenerator,
                                                  const DefinitionMap& definitions) override {
        if (fArguments.size() == 1 && fArguments[0]->fKind == Expression::kIntLiteral_Kind) {
            if (fType == *irGenerator.fContext.fFloat_Type) {
                // promote float(1) to 1.0
                int64_t intValue = ((IntLiteral&) *fArguments[0]).fValue;
                return std::unique_ptr<Expression>(new FloatLiteral(irGenerator.fContext,
                                                                    fPosition,
                                                                    intValue));
            } else if (fType == *irGenerator.fContext.fUInt_Type) {
                // promote uint(1) to 1u
                int64_t intValue = ((IntLiteral&) *fArguments[0]).fValue;
                return std::unique_ptr<Expression>(new IntLiteral(irGenerator.fContext,
                                                                  fPosition,
                                                                  intValue,
                                                                  &fType));
            }
        }
        return nullptr;
    }

    bool hasSideEffects() const override {
        for (const auto& arg : fArguments) {
            if (arg->hasSideEffects()) {
                return true;
            }
        }
        return false;
    }

    String description() const override {
        String result = fType.description() + "(";
        String separator;
        for (size_t i = 0; i < fArguments.size(); i++) {
            result += separator;
            result += fArguments[i]->description();
            separator = ", ";
        }
        result += ")";
        return result;
    }

    bool isConstant() const override {
        for (size_t i = 0; i < fArguments.size(); i++) {
            if (!fArguments[i]->isConstant()) {
                return false;
            }
        }
        return true;
    }

    bool compareConstant(const Context& context, const Expression& other) const override {
        ASSERT(other.fKind == Expression::kConstructor_Kind && other.fType == fType);
        Constructor& c = (Constructor&) other;
        if (c.fType.kind() == Type::kVector_Kind) {
            for (int i = 0; i < fType.columns(); i++) {
                if (!this->getVecComponent(i).compareConstant(context, c.getVecComponent(i))) {
                    return false;
                }
            }
            return true;
        }
        // shouldn't be possible to have a constant constructor that isn't a vector or matrix;
        // a constant scalar constructor should have been collapsed down to the appropriate
        // literal
        ASSERT(fType.kind() == Type::kMatrix_Kind);
        const FloatLiteral fzero(context, Position(), 0);
        const IntLiteral izero(context, Position(), 0);
        const Expression* zero;
        if (fType.componentType() == *context.fFloat_Type) {
            zero = &fzero;
        } else {
            ASSERT(fType.componentType() == *context.fInt_Type);
            zero = &izero;
        }
        for (int col = 0; col < fType.columns(); col++) {
            for (int row = 0; row < fType.rows(); row++) {
                const Expression* component1 = getMatComponent(col, row);
                const Expression* component2 = c.getMatComponent(col, row);
                if (!(component1 ? component1 : zero)->compareConstant(
                                                                context,
                                                                component2 ? *component2 : *zero)) {
                    return false;
                }
            }
        }
        return true;
    }

    const Expression& getVecComponent(int index) const {
        ASSERT(fType.kind() == Type::kVector_Kind);
        if (fArguments.size() == 1 && fArguments[0]->fType.kind() == Type::kScalar_Kind) {
            return *fArguments[0];
        }
        int current = 0;
        for (const auto& arg : fArguments) {
            ASSERT(current <= index);
            if (arg->fType.kind() == Type::kScalar_Kind) {
                if (index == current) {
                    return *arg;
                }
                current++;
            } else {
                ASSERT(arg->fType.kind() == Type::kVector_Kind);
                ASSERT(arg->fKind == Expression::kConstructor_Kind);
                if (current + arg->fType.columns() > index) {
                    return ((const Constructor&) *arg).getVecComponent(index - current);
                }
                current += arg->fType.columns();
            }
        }
        ABORT("failed to find vector component %d in %s\n", index, description().c_str());
    }

    double getFVecComponent(int index) const {
        const Expression& c = this->getVecComponent(index);
        ASSERT(c.fKind == Expression::kFloatLiteral_Kind);
        return ((FloatLiteral&) c).fValue;
    }

    int64_t getIVecComponent(int index) const {
        const Expression& c = this->getVecComponent(index);
        ASSERT(c.fKind == Expression::kIntLiteral_Kind);
        return ((IntLiteral&) c).fValue;
    }

    // null return should be interpreted as zero
    const Expression* getMatComponent(int col, int row) const {
        ASSERT(this->isConstant());
        ASSERT(fType.kind() == Type::kMatrix_Kind);
        ASSERT(col < fType.columns() && row < fType.rows());
        if (fArguments.size() == 1) {
            if (fArguments[0]->fType.kind() == Type::kScalar_Kind) {
                // single scalar argument, so matrix is of the form:
                // x 0 0
                // 0 x 0
                // 0 0 x
                // return x if col == row
                return col == row ? fArguments[0].get() : nullptr;
            }
            if (fArguments[0]->fType.kind() == Type::kMatrix_Kind) {
                ASSERT(fArguments[0]->fKind == Expression::kConstructor_Kind);
                // single matrix argument. make sure we're within the argument's bounds.
                const Type& argType = ((Constructor&) *fArguments[0]).fType;
                if (col < argType.columns() && row < argType.rows()) {
                    // within bounds, defer to argument
                    return ((Constructor&) *fArguments[0]).getMatComponent(col, row);
                }
                // out of bounds, return 0
                return nullptr;
            }
        }
        int currentIndex = 0;
        int targetIndex = col * fType.rows() + row;
        for (const auto& arg : fArguments) {
            ASSERT(targetIndex >= currentIndex);
            ASSERT(arg->fType.rows() == 1);
            if (currentIndex + arg->fType.columns() > targetIndex) {
                if (arg->fType.columns() == 1) {
                    return arg.get();
                } else {
                    ASSERT(arg->fType.kind() == Type::kVector_Kind);
                    ASSERT(arg->fKind == Expression::kConstructor_Kind);
                    return &((Constructor&) *arg).getVecComponent(targetIndex - currentIndex);
                }
            }
            currentIndex += arg->fType.columns();
        }
        ABORT("can't happen, matrix component out of bounds");
    }

    std::vector<std::unique_ptr<Expression>> fArguments;

    typedef Expression INHERITED;
};

} // namespace

#endif