// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2019 Google Inc. All rights reserved.
// http://code.google.com/p/ceres-solver/
//
// 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.
// * Neither the name of Google Inc. nor the names of its contributors may be
//   used to endorse or promote products derived from this software without
//   specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: darius.rueckert@fau.de (Darius Rueckert)

#include "ceres/internal/expression_ref.h"
#include "glog/logging.h"

namespace ceres {
namespace internal {

ExpressionRef ExpressionRef::Create(ExpressionId id) {
  ExpressionRef ref;
  ref.id = id;
  return ref;
}

ExpressionRef::ExpressionRef(double compile_time_constant) {
  id = Expression::CreateCompileTimeConstant(compile_time_constant);
}

ExpressionRef& ExpressionRef::operator=(const ExpressionRef& other) {
  // Assigning an uninitialized variable to another variable is an error.
  CHECK(other.IsInitialized()) << "Uninitialized Assignment.";

  if (IsInitialized()) {
    // Create assignment from other -> this
    Expression::CreateAssignment(id, other.id);
  } else {
    // Special case: "this" expressionref is invalid
    //    -> Skip assignment
    //    -> Let "this" point to the same variable as other
    id = other.id;
  }
  return *this;
}

// Compound operators
ExpressionRef& ExpressionRef::operator+=(ExpressionRef y) {
  *this = *this + y;
  return *this;
}

ExpressionRef& ExpressionRef::operator-=(ExpressionRef y) {
  *this = *this - y;
  return *this;
}

ExpressionRef& ExpressionRef::operator*=(ExpressionRef y) {
  *this = *this * y;
  return *this;
}

ExpressionRef& ExpressionRef::operator/=(ExpressionRef y) {
  *this = *this / y;
  return *this;
}

// Arith. Operators
ExpressionRef operator-(ExpressionRef x) {
  return ExpressionRef::Create(Expression::CreateUnaryArithmetic("-", x.id));
}

ExpressionRef operator+(ExpressionRef x) {
  return ExpressionRef::Create(Expression::CreateUnaryArithmetic("+", x.id));
}

ExpressionRef operator+(ExpressionRef x, ExpressionRef y) {
  return ExpressionRef::Create(
      Expression::CreateBinaryArithmetic("+", x.id, y.id));
}

ExpressionRef operator-(ExpressionRef x, ExpressionRef y) {
  return ExpressionRef::Create(
      Expression::CreateBinaryArithmetic("-", x.id, y.id));
}

ExpressionRef operator/(ExpressionRef x, ExpressionRef y) {
  return ExpressionRef::Create(
      Expression::CreateBinaryArithmetic("/", x.id, y.id));
}

ExpressionRef operator*(ExpressionRef x, ExpressionRef y) {
  return ExpressionRef::Create(
      Expression::CreateBinaryArithmetic("*", x.id, y.id));
}

// Functions
ExpressionRef sin(ExpressionRef x) {
  return ExpressionRef::Create(Expression::CreateFunctionCall("sin", {x.id}));
}

ExpressionRef Ternary(ComparisonExpressionRef c,
                      ExpressionRef a,
                      ExpressionRef b) {
  return ExpressionRef::Create(Expression::CreateTernary(c.id, a.id, b.id));
}

#define CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(op)                   \
  ComparisonExpressionRef operator op(ExpressionRef a, ExpressionRef b) { \
    return ComparisonExpressionRef(ExpressionRef::Create(                 \
        Expression::CreateBinaryCompare(#op, a.id, b.id)));               \
  }

#define CERES_DEFINE_EXPRESSION_LOGICAL_OPERATOR(op)               \
  ComparisonExpressionRef operator op(ComparisonExpressionRef a,   \
                                      ComparisonExpressionRef b) { \
    return ComparisonExpressionRef(ExpressionRef::Create(          \
        Expression::CreateBinaryCompare(#op, a.id, b.id)));        \
  }

CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(<)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(<=)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(>)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(>=)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(==)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(!=)
CERES_DEFINE_EXPRESSION_LOGICAL_OPERATOR(&&)
CERES_DEFINE_EXPRESSION_LOGICAL_OPERATOR(||)
#undef CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR
#undef CERES_DEFINE_EXPRESSION_LOGICAL_OPERATOR

ComparisonExpressionRef operator!(ComparisonExpressionRef a) {
  return ComparisonExpressionRef(
      ExpressionRef::Create(Expression::CreateLogicalNegation(a.id)));
}

}  // namespace internal
}  // namespace ceres