/* Copyright 2017 - 2022 R. Thomas
 * Copyright 2017 - 2022 Quarkslab
 * Copyright 2017 - 2021, NVIDIA CORPORATION. All rights reserved.
 *
 * 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.
 */
#ifndef LIEF_ITERATORS_H_
#define LIEF_ITERATORS_H_
#include <iostream>
#include <cmath>
#include <cstddef>
#include <cassert>
#include <iterator>
#include <functional>
#include <algorithm>
#include <type_traits>
#include <vector>

#include "LIEF/exception.hpp"

namespace LIEF {

template<class T>
using decay_t = typename std::decay<T>::type;

template<class T>
using add_const_t = typename std::add_const<T>::type;

template<class T>
using remove_const_t = typename std::remove_const<T>::type;

template< class T >
using add_lvalue_reference_t = typename std::add_lvalue_reference<T>::type;


//! Iterator which returns reference on container's values
template<class T, typename U = typename decay_t<T>::value_type,
         class ITERATOR_T = typename decay_t<T>::iterator>
class ref_iterator {
  public:
  using iterator_category = std::bidirectional_iterator_tag;
  using value_type = decay_t<U>;
  using difference_type = ptrdiff_t;
  using pointer = typename std::remove_pointer<U>::type*;
  using reference = typename std::remove_pointer<U>::type&;
                              
  using container_type = T;          // e.g. std::vector<Section*>&
  using DT_VAL         = U;          // e.g. Section*
  using DT             = decay_t<T>; // e.g. std::vector<Section>
  using ref_t          = typename ref_iterator::reference;
  using pointer_t      = typename ref_iterator::pointer;

  ref_iterator(T container) :
    container_{std::forward<T>(container)},
    distance_{0}
  {
    it_ = std::begin(container_);
  }

  ref_iterator(const ref_iterator& copy) :
    container_{copy.container_},
    it_{std::begin(container_)},
    distance_{copy.distance_}
  {
    std::advance(it_, distance_);
  }


  ref_iterator operator=(ref_iterator other) {
    swap(other);
    return *this;
  }

  void swap(ref_iterator& other) {
    std::swap(const_cast<add_lvalue_reference_t<remove_const_t<DT>>>(container_),
              const_cast<add_lvalue_reference_t<remove_const_t<DT>>>(other.container_));
    std::swap(it_, other.it_);
    std::swap(distance_, other.distance_);
  }


  ref_iterator& operator++() {
    it_ = std::next(it_);
    distance_++;
    return *this;
  }

  ref_iterator operator++(int) {
    ref_iterator retval = *this;
    ++(*this);
    return retval;
  }

  ref_iterator& operator--() {
    if (it_ != std::begin(container_)) {
      it_ = std::prev(it_);
      distance_--;
    }
    return *this;
  }

  ref_iterator operator--(int) {
    ref_iterator retval = *this;
    --(*this);
    return retval;
  }


  ref_iterator& operator+=(const typename ref_iterator::difference_type& movement) {
    std::advance(it_, movement);
    distance_ += movement;
    return *this;
  }


  ref_iterator& operator-=(const typename ref_iterator::difference_type& movement) {
    return (*this) += -movement;
  }


  typename std::enable_if<!std::is_const<ref_t>::value, remove_const_t<ref_t>>::type
  operator[](size_t n) {
    return const_cast<remove_const_t<ref_t>>(static_cast<const ref_iterator*>(this)->operator[](n));
  }


  add_const_t<ref_t> operator[](size_t n) const {
    assert(n < size() && "integrity error: out of bound");

    ref_iterator* no_const_this = const_cast<ref_iterator*>(this);

    typename ref_iterator::difference_type saved_dist = std::distance(std::begin(no_const_this->container_), no_const_this->it_);
    no_const_this->it_ = std::begin(no_const_this->container_);
    std::advance(no_const_this->it_, n);

    auto&& v = const_cast<add_const_t<ref_t>>(no_const_this->operator*());

    no_const_this->it_ = std::begin(no_const_this->container_);
    std::advance(no_const_this->it_, saved_dist);

    return v;
  }

  ref_iterator operator+(typename ref_iterator::difference_type n) const {
    ref_iterator tmp = *this;
    return tmp += n;
  }


  ref_iterator operator-(typename ref_iterator::difference_type n) const {
    ref_iterator tmp = *this;
    return tmp -= n;
  }


  typename ref_iterator::difference_type operator-(const ref_iterator& rhs) const {
    return distance_ - rhs.distance_;
  }

  bool operator<(const ref_iterator& rhs) const {
    return (rhs - *this) > 0;
  }


  bool operator>(const ref_iterator& rhs) const {
    return rhs < *this;
  }


  bool operator>=(const ref_iterator& rhs) const {
    return !(*this < rhs);
  }


  bool operator<=(const ref_iterator& rhs) const {
    return !(*this > rhs);
  }

  ref_iterator begin() const {
    return container_;
  }

  ref_iterator cbegin() const {
    return begin();
  }

  ref_iterator end()  const {
    ref_iterator it = ref_iterator{container_};
    it.it_ = std::end(it.container_);
    it.distance_ = it.size();
    return it;
  }

  ref_iterator cend() const {
    return end();
  }

  bool operator==(const ref_iterator& other) const {
    return (size() == other.size() && distance_ == other.distance_);
  }

  bool operator!=(const ref_iterator& other) const {
    return !(*this == other);
  }

  size_t size() const {
    return container_.size();
  }

  bool empty() const {
    return container_.empty();
  }

  typename std::enable_if<!std::is_const<ref_t>::value, remove_const_t<ref_t>>::type
  operator*() {
    return const_cast<remove_const_t<ref_t>>(static_cast<const ref_iterator*>(this)->operator*());
  }

  template<typename V = DT_VAL>
  typename std::enable_if<std::is_pointer<V>::value, add_const_t<ref_t>>::type
  operator*() const {
    assert(*it_ && "integrity error: nullptr");
    return const_cast<add_const_t<ref_t>>(**it_);
  }

  template<typename V = DT_VAL>
  typename std::enable_if<!std::is_pointer<V>::value, add_const_t<ref_t>>::type
  operator*() const {
    return const_cast<add_const_t<ref_t>>(*(it_));
  }


  typename std::enable_if<!std::is_const<pointer_t>::value, pointer_t>::type
  operator->() {
    return const_cast<remove_const_t<pointer_t>>(static_cast<const ref_iterator*>(this)->operator->());
  }

  add_const_t<pointer_t> operator->() const {
    return const_cast<add_const_t<pointer_t>>(&(operator*()));
  }

  protected:
  T container_;
  ITERATOR_T it_;
  typename ref_iterator::difference_type distance_;
};


//! Iterator which return const ref on container's values
template<class T, typename U = typename decay_t<T>::value_type, class CT = typename std::add_const<T>::type>
using const_ref_iterator = ref_iterator<CT, U, typename decay_t<CT>::const_iterator>;


//! Iterator which return a ref on container's values given predicates
template<class T, typename U = typename decay_t<T>::value_type,
         class ITERATOR_T = typename decay_t<T>::iterator>
class filter_iterator {

  public:
  using iterator_category = std::forward_iterator_tag;
  using value_type = decay_t<U>;
  using difference_type = ptrdiff_t;
  using pointer = typename std::remove_pointer<U>::type*;
  using reference = typename std::remove_pointer<U>::type&;

  using container_type = T;
  using DT_VAL         = U;
  using DT        = decay_t<T>;
  using ref_t     = typename filter_iterator::reference;
  using pointer_t = typename filter_iterator::pointer;
  using filter_t  = std::function<bool (const typename DT::value_type&)>;

  filter_iterator(T container, filter_t filter) :
    size_c_{0},
    container_{std::forward<T>(container)},
    filters_{},
    distance_{0}
  {

    it_ = std::begin(container_);

    filters_.push_back(filter),
    it_ = std::begin(container_);

    if (it_ != std::end(container_)) {
      if (!std::all_of(std::begin(filters_), std::end(filters_), [this] (const filter_t& f) {return f(*it_);})) {
        next();
      }
    }
  }

  filter_iterator(T container, const std::vector<filter_t>& filters) :
    size_c_{0},
    container_{std::forward<T>(container)},
    filters_{filters},
    distance_{0}
  {

    it_ = std::begin(container_);

    if (it_ != std::end(container_)) {
      if (!std::all_of(std::begin(filters_), std::end(filters_), [this] (const filter_t& f) {return f(*it_);})) {
        next();
      }
    }
  }

  filter_iterator(T container) :
    size_c_{0},
    container_{std::forward<T>(container)},
    filters_{},
    distance_{0}
  {
    it_ = std::begin(container_);
  }

  filter_iterator(const filter_iterator& copy) :
    size_c_{0},
    container_{copy.container_},
    it_{std::begin(container_)},
    filters_{copy.filters_},
    distance_{copy.distance_}
  {
    std::advance(it_, distance_);
  }

  filter_iterator operator=(filter_iterator other) {
    swap(other);
    return *this;
  }

  void swap(filter_iterator& other) {
    std::swap(const_cast<remove_const_t<DT>&>(container_), const_cast<remove_const_t<DT>&>(other.container_));
    std::swap(it_,        other.it_);
    std::swap(filters_,   other.filters_);
    std::swap(size_c_,    other.size_c_);
    std::swap(distance_,  other.distance_);
  }


  filter_iterator& def(filter_t func) {
    filters_.push_back(func);
    size_c_ = 0;
    return *this;
  }

  filter_iterator& operator++() {
    next();
    return *this;
  }

  filter_iterator operator++(int) {
    filter_iterator retval = *this;
    ++(*this);
    return retval;
  }

  filter_iterator begin() const {
    return {container_, filters_};
  }

  filter_iterator cbegin() const {
    return begin();
  }

  filter_iterator end() const {
    // we don't need filter for the end iterator
    filter_iterator it_end{container_};

    it_end.it_       =  it_end.container_.end();
    it_end.distance_ = it_end.container_.size();

    return it_end;
  }

  filter_iterator cend() const {
    return end();
  }

  typename std::enable_if<!std::is_const<ref_t>::value, remove_const_t<ref_t>>::type
  operator*() {
    return const_cast<remove_const_t<ref_t>>(static_cast<const filter_iterator*>(this)->operator*());
  }

  template<typename V = DT_VAL>
  typename std::enable_if<std::is_pointer<V>::value, add_const_t<ref_t>>::type
  operator*() const {
    assert(*it_ && "integrity error: nullptr");
    return const_cast<add_const_t<ref_t>>(**it_);
  }

  template<typename V = DT_VAL>
  typename std::enable_if<!std::is_pointer<V>::value, add_const_t<ref_t>>::type
  operator*() const {
    return const_cast<add_const_t<ref_t>>(*(it_));
  }


  typename std::enable_if<!std::is_const<ref_t>::value, remove_const_t<ref_t>>::type
  operator[](size_t n) {
    return const_cast<remove_const_t<ref_t>>(static_cast<const filter_iterator*>(this)->operator[](n));
  }

  add_const_t<ref_t> operator[](size_t n) const {
    assert(n < size() && "integrity error: out of bound");

    auto it = begin();
    std::advance(it, n);
    return const_cast<add_const_t<ref_t>>(*it);
  }


  typename std::enable_if<!std::is_const<pointer_t>::value, pointer_t>::type
  operator->() {
    return const_cast<remove_const_t<pointer_t>>(static_cast<const filter_iterator*>(this)->operator->());
  }

  add_const_t<pointer_t> operator->() const {
    return const_cast<add_const_t<pointer_t>>(&(operator*()));
  }

  size_t size() const {
    if (filters_.size() == 0) {
      return container_.size();
    }

    if (size_c_ > 0) {
      return size_c_;
    }
    filter_iterator it = begin();
    size_t size = 0;

    auto end_iter = std::end(it);
    for (; it != end_iter; ++it) ++size;
    size_c_ = size;
    return size_c_;
  }


  bool empty() const {
    return size() == 0;
  }


  bool operator==(const filter_iterator& other) const {
    return (container_.size() == other.container_.size() && distance_ == other.distance_);
  }

  bool operator!=(const filter_iterator& other) const {
    return !(*this == other);
  }

  protected:
  void next() {
    if (it_ == std::end(container_)) {
      distance_ = container_.size();
      return;
    }

    do {
      it_ = std::next(it_);
      distance_++;
    } while(it_ != std::end(container_) &&
            !std::all_of(std::begin(filters_), std::end(filters_),
                         [this] (const filter_t& f) { return f(*it_); }));

  }


  mutable size_t size_c_;
  T container_;
  ITERATOR_T it_;
  std::vector<filter_t> filters_;
  typename filter_iterator::difference_type distance_;
};

//! Iterator which return a const ref on container's values given predicates
template<class T, typename U = typename decay_t<T>::value_type,
         class CT = typename std::add_const<T>::type>
using const_filter_iterator = filter_iterator<CT, U, typename decay_t<CT>::const_iterator>;

}

#endif