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#include "src/tint/lang/wgsl/helpers/apply_substitute_overrides.h"

#include <memory>
#include <utility>

#include "src/tint/lang/wgsl/ast/transform/manager.h"
#include "src/tint/lang/wgsl/ast/transform/substitute_override.h"
#include "src/tint/lang/wgsl/inspector/inspector.h"
#include "src/tint/lang/wgsl/program/program.h"

namespace tint::wgsl {

std::optional<Program> ApplySubstituteOverrides(const Program& program) {
    ast::transform::SubstituteOverride::Config cfg;
    inspector::Inspector inspector(program);
    auto default_values = inspector.GetOverrideDefaultValues();
    for (const auto& [override_id, scalar] : default_values) {
        // If the override is not null, then it has a default value, we can just let it use the
        // provided default instead of overriding.
        if (scalar.IsNull()) {
            cfg.map.insert({override_id, 0.0});
        }
    }

    if (default_values.empty()) {
        return std::nullopt;
    }

    ast::transform::DataMap override_data;
    override_data.Add<ast::transform::SubstituteOverride::Config>(cfg);

    ast::transform::Manager mgr;
    mgr.append(std::make_unique<ast::transform::SubstituteOverride>());

    ast::transform::DataMap outputs;
    return mgr.Run(program, override_data, outputs);
}

}  // namespace tint::wgsl
