#include <stdexcept>
#include <cassert>
#include "../Headers/LinkedList.h"

LinkedList::LinkedList() {
    first = last = nullptr;
    size = 0;
}

LinkedList::~LinkedList() {
    while (first) {
        Node* n = first;
        delete first;
        first = n;
    }
}

int LinkedList::GetFront() const {
    if (isEmpty()) {
        throw std::runtime_error("List is empty");
    }
    return first->data;
}

int LinkedList::GetLast() const {
    if (isEmpty()) {
        throw std::runtime_error("List is empty");
    }
    return last->data;
}

void LinkedList::insertFront(int x) {
    Node* node = new Node;
    node->data = x;
    node->next = first;

    if (isEmpty()) {
        last = node;
    }

    first = node;
    ++size;
}

void LinkedList::insertBack(int x) {
    Node* node = new Node;
    node->data = x;
    node->next = nullptr;

    if (isEmpty()) {
        first = node;
        last = node;
    } else {
        last->next = node;
        last = node;
    }
    ++size;
}

void LinkedList::removeFront() {
    if (isEmpty()) {
        throw std::runtime_error("List is empty");
    }

    Node* node = first;
    first = first->next;
    delete node;

    if (size == 1) {
        last = first;
    }
    --size;
}

bool LinkedList::isEmpty() const {
    return size == 0;
}

void LinkedList::insertAfter(Node *it, int x) {
    assert( it != nullptr);

    Node* node = new Node;
    node->next = it->next;
    node->data = x;
    it->next = node;

    if (it == last) {
        last = node;
    }

    ++size;
}

void LinkedList::RemoveAfter(Node *it) {
    assert(it != nullptr);
    bool changeLast = (it->next == last);

    if (it == last) {
        std::runtime_error("cannot remove");
    }

    Node* n = it->next;
    it->next = it->next->next;
    delete n;

    --size;
}

bool predicate(int val) {
    return val == 5;
}

const Node* find(const Node* first) {
    while (first != nullptr && !predicate(first->data)) {
        first = first->next;
    }
    return first;
}