class Queue {
    constructor() {
        this.q = [];
    }

    enqueue(x) {
        this.q.push(x);
    }

    dequeue() {
        return this.q.shift();
    }

    isEmpty() {
        return this.q.length == 0;
    }
}

class RankedTree {
    constructor() {
        this.root = null;
        this.recorder = null;
    }

    _getUnwrappedGraph() {
        let result = [];

        let q = new Queue();
        q.enqueue(this.root);

        let edges = [];
        while (!q.isEmpty()) {
            let node = q.dequeue();
            if (!node) {
                continue;
            }

            let [value, rank] = [node.value, node.rank];
            result.push(`\t"Node(${value})" [label="${value}, ${rank}"];`);

            [node.left, node.right]
                .filter((child) => child)
                .forEach((child) => {
                    edges.push([node, child]);
                    q.enqueue(child);
                });
        }

        result.push("");

        edges.forEach((vertices) => {
            let [u, v] = vertices;
            result.push(
                `\t"Node(${u.value})" -> "Node(${
                    v.value
                })" [label="${nodeDifference(v)}"]`
            );
        });

        return result;
    }

    toDot() {
        return ["digraph {", ...this._getUnwrappedGraph(), "}"];
    }

    toString() {
        return this.toDot().join("\n");
    }

    record() {
        if (!this.recorder) {
            return;
        }
        this.recorder.record(this);
    }

    rank() {
        return nodeRank(this.root);
    }

    isCorrect() {
        return this.isCorrectNode(this.root);
    }

    search(value, node) {
        return nodeSearch(value, node || this.root);
    }

    insert(value) {
        let insertedNode = new Node(value);

        if (!this.root) {
            this.root = insertedNode;
            this.record();
            return;
        }

        let parent = findParentNode(value, this.root);
        if (!parent) {
            return;
        }

        insertedNode.parent = parent;

        if (value < parent.value) {
            parent.left = insertedNode;
        } else {
            parent.right = insertedNode;
        }
        this.record();

        this.insertRebalance(insertedNode);
    }

    transplant(u, v) {
        if (!u.parent) {
            this.root = v;
        } else if (u.parent.left === u) {
            u.parent.left = v;
        } else {
            u.parent.right = v;
        }

        if (v) {
            v.rank = u.rank;
            v.parent = u.parent;
        }
    }

    deleteNode(node) {
        if (!node) {
            return null;
        }

        let [y, parent] = [null, node.parent];

        if (!node.left) {
            y = node.right;
            this.transplant(node, node.right);
        } else if (!node.right) {
            y = node.left;
            this.transplant(node, node.left);
        } else {
            let successor = nodeMinimum(node.right);

            node.value = successor.value;
            successor.value = null;
            this.record();

            return this.deleteNode(successor);
        }

        this.record();

        return [y, parent];
    }

    delete(value) {
        let node = this.root;
        while (node && node.value != value) {
            node = value < node.value ? node.left : node.right;
        }

        let toRebalance = this.deleteNode(node);
        if (toRebalance) {
            let [y, parent] = toRebalance;
            this.deleteRebalance(y, parent);
        }
    }

    /* abstract methods */
    isCorrectNode(node) {
        throw "not implemented!";
    }

    insertRebalance(node) {
        throw "not implemented!";
    }

    deleteRebalance(node, parent) {
        throw "not implemented!";
    }
}