class LinkedList {
    constructor() {
        this.size = 0;
        this.tail = null;
        this.head = null;
    }

    getHead() {
        return this.tail;
    }
    getTail() {
        return this.head;
    }

    getSize() {
        return this.size;
    }

    append(value) {
        let newNode = new Node(value);
        if (this.head == null) {
            this.head = newNode;
        } else {
            const temp = this.head;
            this.head = newNode;
            this.head.nextNode = temp;
        }
        if (this.tail == null) {
            this.tail = newNode;
        }

        this.size += 1;
    }

    prepend(value) {
        let newNode = new Node(value);
        if (this.tail == null) {
            this.tail = newNode;
            if (this.head == null) {
                this.head = newNode;
            }
        } else {
            const temp = this.tail;
            temp.nextNode = newNode;
            this.tail = newNode;
        }
        this.size += 1;
    }

    at(index) {
        function nodeAtIndex(index, count, node) {
            if (index === count) {
                return node;
            } else if (node.nextNode == null) {
                return null;
            } else {
                return nodeAtIndex(index, count + 1, node.nextNode);
            }
        }

        return nodeAtIndex(index, 0, this.head);
    }
    pop() {
        if (this.head.nextNode == null) {
            this.head = null;
            this.tail = null;
        } else {
            this.head = this.head.nextNode;
        }
        this.size -= 1;
    }

    contains(value) {
        function searchNodes(node, value) {
            if (node.value === value) {
                return true;
            } else if (node.nextNode == null) {
                return false;
            } else {
                return searchNodes(node.nextNode, value);
            }
        }

        return searchNodes(this.head, value);
    }

    find(value) {
        let index = 0;
        function searchNodes(node, value, index) {
            if (node.value === value) {
                return index;
            } else if (node.nextNode == null) {
                return null;
            } else {
                return searchNodes(node.nextNode, value, index + 1);
            }
        }

        return searchNodes(this.head, value, index);
    }

    insertAt(value, index) {
        let previousNode = null;
        let newNode = new Node(value);
        let currentNode = this.head;
        let count = 0;

        if (index === 0) {
            this.append(value);
            return;
        }

        while (currentNode != null) {
            if (count == index) {
                if (currentNode.nextNode == null) {
                    this.prepend(value);
                    return;
                } else {
                    let nextNode = currentNode;
                    previousNode.nextNode = newNode;
                    newNode.nextNode = nextNode;
                    return;
                }
            }

            previousNode = currentNode;
            currentNode = currentNode.nextNode;
            count += 1;
        }
    }

    removeAt(index) {
        let previousNode = null;
        let currentNode = this.head;
        let count = 0;

        if (index === 0) {
            this.pop();
            return;
        }

        while (currentNode != null) {
            if (count == index) {
                if (currentNode.nextNode == null) {
                    previousNode.nextNode = null;
                    return;
                } else {
                    previousNode.nextNode = currentNode.nextNode;
                    return;
                }
            }

            previousNode = currentNode;
            currentNode = currentNode.nextNode;
            count += 1;
        }
    }

    toString() {
        let nodes = [];
        let current = this.head;

        while (current != null) {
            nodes.push(current.value);
            current = current.nextNode;
        }

        console.log(nodes.join(' -> ') + ' -> null');
    }

    remove(value) {
        let count = 0;
        let previousNode = null;
        let currentNode = this.head;

        if (this.head.value === value) {
            this.pop();
            return;
        }

        while (currentNode) {
            if (currentNode.value === value) {
                previousNode.nextNode = currentNode.nextNode;
                return;
            }
            previousNode = currentNode;
            currentNode = currentNode.nextNode;
        }
    }
}

class Node {
    constructor(value) {
        this.value = value;
        this.nextNode = null;
    }
}

// let list = new LinkedList();
//
// list.append('test 5');
// list.prepend('test 8');
// list.append('test 1');
// list.append('test 2');
// list.append('test 3');
// list.append('test 4');
// list.prepend('Deez Nuts');
// list.toString();
// console.log(list.find('Deez Nuts'));
// console.log(list.find('test '));
// console.log(list.contains('test 3'));
//
// console.log(list.size);
// console.log(list.at(1).value);
// console.log('popping last element');
// list.pop();
// list.toString();
// list.insertAt('inserted 3', 3);
// // list.insertAt("inserted 1", 1);
// list.toString();
// list.insertAt('inserted 1', 1);
// list.toString();
// list.removeAt(6);
// console.log('Removing element 6');
// list.toString();
// console.log('removing inserted elements');
// list.removeAt(1);
// list.removeAt(3);
// list.toString();
// console.log('Removing element 1');
// list.removeAt(0);
// list.toString();
// console.log('Removing element Deez Nuts');
// list.removeAt(3);
// list.toString();
export { LinkedList };
