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import { LinkedListApi, NodeType, DataType, Node } from "./helper.ts";

export class SinglyLinkedList implements LinkedListApi {	private head: null|NodeType	private tail: null|NodeType	public size: number
	constructor() {		this.head = null		this.tail = null		this.size = 0	}
	// insert in the head	prepend(data: DataType<any>) {		if (this.head === null) {			const newNode = new Node(data);			this.head = newNode			this.tail = newNode			return true;		}
		const currentNode = this.head		this.head = new Node(data)		this.head.next = currentNode		if (currentNode.next === null) {			this.tail = currentNode		}		this.size++
		return true;	}
	// inset in the tail	append(data: DataType<any>) {		if (this.head === null) {			const newNode = new Node(data);			this.head = newNode			this.tail = newNode			return true;		}
		let currentNode: NodeType = this.head		while (currentNode !== null) {			const newItem = new Node(data);			this.tail = newItem
			if (currentNode.next === null) {				currentNode.next = newItem
				this.size++;				return true;			}			currentNode = currentNode.next		}
		return false;	}
	// // add anywhere of the linked list except head & tail	add(data: DataType<any>, position: number) {		if (position === 0) {			console.error("Use `prepend()` method to insert data at Head.");			return false;		} else if (position === this.size) {			console.error("Use `append()` method to insert data at Tail.");			return false;		} else if (position > this.size && position != this.size + 1) {			console.error(`Out of range. Size of the linkedList is ${this.size}`);			return false;		}			let prevNode: NodeType = null;		let currentNode = this.head		let count = 0		while (currentNode !== null) {			if (count === position) {				prevNode!.next = new Node(data)				prevNode!.next.next = currentNode				this.size++			}				prevNode = currentNode			currentNode = currentNode.next			count++		}
		return true;	}
	getFromHead() {		if (this.head === null) {			return false		}
		return this.head.data;	}
	getFromTail() {		if (this.tail === null) {			return false		}
		return this.tail.data	}
	print() {		let currentNode = this.head		while (currentNode !== null) {			console.log(currentNode.data);			currentNode = currentNode.next		}	}
	remove(key: string|number) {		if (this.head === null) {			return false;		} else if (this.head!.next === null) {			this.tail = null		}		if (this.head.data.key === key) {			const prevHeadData = this.head.data			this.head = this.head.next			if (this.head!.next === null) this.tail = this.head
			this.size--			if (this.head === null) this.size = 0			return prevHeadData;		}
		// two pointer approach		let previousNode: NodeType = null;		let currentNode: NodeType = this.head		while (currentNode !== null) {			if (key === currentNode.data.key) {				const temp = currentNode.data				previousNode!.next = currentNode.next				if (currentNode!.next === null) this.tail = previousNode
				this.size--				return temp;			}
			previousNode = currentNode			currentNode = currentNode.next		}
		return false;	}
	update(key: string|number, newValue: any) {		if (this.head === null) {			return false;		}
		if (this.head.data.key === key) {			this.head.data.value = newValue			return this.head.data;		}		if (this.tail!.data.key === key) {			this.tail!.data.value = newValue		}
		let currentNode = this.head.next		while (currentNode !== null) {			if (currentNode.data.key === key) {				currentNode.data.value = newValue				return currentNode.data;			}
			currentNode = currentNode.next		}
		return false;	}
	search(key: string|number) {		if (this.head === null) {			return null;		}
		if (this.head.data.key === key) {			return this.head.data;		}		if (this.tail!.data.key === key) {			return this.tail!.data		}
		let currentNode = this.head.next		while (currentNode !== null) {			if (currentNode.data.key === key) {				return currentNode.data;			}
			currentNode = currentNode.next		}
		return null;	}}