// Copyright (c) 2021, Viktor Larsson
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
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//       names of its contributors may be used to endorse or promote products
//       derived from this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#ifndef POSELIB_HYBRID_H_
#define POSELIB_HYBRID_H_

#include "../../types.h"
#include "optim_utils.h"
#include "refiner_base.h"

namespace poselib {

// Composite refiner
// It is possible to use different robust loss functions for each refiner
// If no loss function is provided for a refiner, the current loss function in the accumulator is used
// Note: Requires all refiners to have the same model and step-function!
template <typename Model = CameraPose, typename Accumulator = NormalAccumulator>
class HybridRefiner : public RefinerBase<Model, Accumulator> {
  public:
    HybridRefiner() {}

    double compute_residual(Accumulator &acc, const Model &model) {

        for (int i = 0; i < refiners.size(); ++i) {
            RefinerBase<Model, Accumulator> *ref = refiners[i];
            std::shared_ptr<RobustLoss> loss_fcn = loss_fcns[i];
            std::shared_ptr<RobustLoss> old_loss = acc.loss_fcn;
            if (loss_fcn.get() != nullptr) {
                acc.loss_fcn = loss_fcn;
            }
            ref->compute_residual(acc, model);
            acc.loss_fcn = old_loss;
        }
        return acc.get_residual();
    }

    void compute_jacobian(Accumulator &acc, const Model &model) {
        for (int i = 0; i < refiners.size(); ++i) {
            RefinerBase<Model, Accumulator> *ref = refiners[i];
            std::shared_ptr<RobustLoss> loss_fcn = loss_fcns[i];
            std::shared_ptr<RobustLoss> old_loss = acc.loss_fcn;
            if (loss_fcn.get() != nullptr) {
                acc.loss_fcn = loss_fcn;
            }
            ref->compute_jacobian(acc, model);
            acc.loss_fcn = old_loss;
        }
    }

    Model step(const Eigen::VectorXd &dp, const Model &model) const {
        // Assumption is that all step() functions are the same
        return refiners[0]->step(dp, model);
    }

    void register_refiner(RefinerBase<Model, Accumulator> *ref, std::shared_ptr<RobustLoss> loss_fcn = nullptr) {
        refiners.push_back(ref);
        loss_fcns.push_back(loss_fcn);
        num_params = std::max(num_params, ref->num_params);
    }

    typedef Model param_t;
    size_t num_params = 0;
    std::vector<RefinerBase<Model, Accumulator> *> refiners;
    std::vector<std::shared_ptr<RobustLoss>> loss_fcns;
};

} // namespace poselib

#endif