// Copyright 2021 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "src/tint/transform/vectorize_scalar_matrix_constructors.h"

#include <utility>

#include "src/tint/program_builder.h"
#include "src/tint/sem/call.h"
#include "src/tint/sem/expression.h"
#include "src/tint/sem/type_constructor.h"

TINT_INSTANTIATE_TYPEINFO(tint::transform::VectorizeScalarMatrixConstructors);

namespace tint::transform {

VectorizeScalarMatrixConstructors::VectorizeScalarMatrixConstructors() = default;

VectorizeScalarMatrixConstructors::~VectorizeScalarMatrixConstructors() = default;

bool VectorizeScalarMatrixConstructors::ShouldRun(const Program* program, const DataMap&) const {
    for (auto* node : program->ASTNodes().Objects()) {
        if (auto* call = program->Sem().Get<sem::Call>(node)) {
            if (call->Target()->Is<sem::TypeConstructor>() && call->Type()->Is<sem::Matrix>()) {
                auto& args = call->Arguments();
                if (args.size() > 0 && args[0]->Type()->is_scalar()) {
                    return true;
                }
            }
        }
    }
    return false;
}

void VectorizeScalarMatrixConstructors::Run(CloneContext& ctx, const DataMap&, DataMap&) const {
    ctx.ReplaceAll([&](const ast::CallExpression* expr) -> const ast::CallExpression* {
        auto* call = ctx.src->Sem().Get(expr);
        auto* ty_ctor = call->Target()->As<sem::TypeConstructor>();
        if (!ty_ctor) {
            return nullptr;
        }
        // Check if this is a matrix constructor with scalar arguments.
        auto* mat_type = call->Type()->As<sem::Matrix>();
        if (!mat_type) {
            return nullptr;
        }

        auto& args = call->Arguments();
        if (args.size() == 0) {
            return nullptr;
        }
        if (!args[0]->Type()->is_scalar()) {
            return nullptr;
        }

        // Build a list of vector expressions for each column.
        ast::ExpressionList columns;
        for (uint32_t c = 0; c < mat_type->columns(); c++) {
            // Build a list of scalar expressions for each value in the column.
            ast::ExpressionList row_values;
            for (uint32_t r = 0; r < mat_type->rows(); r++) {
                row_values.push_back(ctx.Clone(args[c * mat_type->rows() + r]->Declaration()));
            }

            // Construct the column vector.
            auto* col =
                ctx.dst->vec(CreateASTTypeFor(ctx, mat_type->type()), mat_type->rows(), row_values);
            columns.push_back(col);
        }
        return ctx.dst->Construct(CreateASTTypeFor(ctx, mat_type), columns);
    });

    ctx.Clone();
}

}  // namespace tint::transform