export default class BiMap {
    constructor(items = []) {
        this._valueForKey = new Map;
        this._keyForValue = new Map;

        for (let [key, value] of items)
            this.set(key, value);
    }

    // Public

    get size() {
        return this._valueForKey.size;
    }

    has(key) {
        return this.hasKey(key);
    }

    hasKey(key) {
        return this._valueForKey.has(key);
    }

    hasValue(value) {
        return this._keyForValue.has(value);
    }

    get(key) {
        return this.getValue(key);
    }

    getValue(key) {
        return this._valueForKey.get(key);
    }

    getKey(value) {
        return this._keyForValue.get(value);
    }

    set(key, value) {
        this.deleteKey(key);
        this.deleteValue(value);

        this._valueForKey.set(key, value);
        this._keyForValue.set(value, key);

        console.assert(this._valueForKey.size === this._keyForValue.size, this);
    }

    delete(key) {
        return this.deleteKey(key);
    }

    deleteKey(key) {
        let value = this.getValue(key);
        let deletedKey = this._valueForKey.delete(key);
        let deletedValue = this._keyForValue.delete(value);
        console.assert(deletedKey === deletedValue, this);
        console.assert(this._valueForKey.size === this._keyForValue.size, this);
        return deletedKey;
    }

    deleteValue(value) {
        let key = this.getKey(value);
        let deletedKey = this._valueForKey.delete(key);
        let deletedValue = this._keyForValue.delete(value);
        console.assert(deletedKey === deletedValue, this);
        console.assert(this._valueForKey.size === this._keyForValue.size, this);
        return deletedValue;
    }

    take(key) {
        return this.takeKey(key);
    }

    takeKey(key) {
        let value = this.getValue(key);
        let deletedKey = this._valueForKey.delete(key);
        let deletedValue = this._keyForValue.delete(value);
        console.assert(deletedKey === deletedValue, this);
        console.assert(this._valueForKey.size === this._keyForValue.size, this);
        return value;
    }

    takeValue(value) {
        let key = this.getKey(value);
        let deletedKey = this._valueForKey.delete(key);
        let deletedValue = this._keyForValue.delete(value);
        console.assert(deletedKey === deletedValue, this);
        console.assert(this._valueForKey.size === this._keyForValue.size, this);
        return key;
    }

    clear() {
        this._valueForKey.clear();
        this._keyForValue.clear();
    }

    keys() {
        return this._valueForKey.keys();
    }

    values() {
        return this._valueForKey.values();
    }

    entries() {
        return this._valueForKey.entries();
    }

    [Symbol.iterator]() {
        return this._valueForKey[Symbol.iterator]();
    }

    toJSON() {
        return Array.from(this);
    }
}