//================================================================
/**
 * @packageDocumentation
 * @module std
 */
//================================================================
import { MultiSet } from "../base/container/MultiSet";
import { IHashSet } from "../base/container/IHashSet";
import { IHashContainer } from "../internal/container/associative/IHashContainer";

import { SetElementList } from "../internal/container/associative/SetElementList";
import { SetHashBuckets } from "../internal/hash/SetHashBuckets";

import { IForwardIterator } from "../iterator/IForwardIterator";
import { BinaryPredicator } from "../internal/functional/BinaryPredicator";
import { Hasher } from "../internal/functional/Hasher";
import { Temporary } from "../internal/functional/Temporary";

/**
 * Multiple-key Set based on Hash buckets.
 *
 * @author Jeongho Nam - https://github.com/samchon
 */
export class HashMultiSet<Key>
    extends MultiSet<
        Key,
        HashMultiSet<Key>,
        HashMultiSet.Iterator<Key>,
        HashMultiSet.ReverseIterator<Key>
    >
    implements IHashSet<Key, false, HashMultiSet<Key>>
{
    private buckets_!: SetHashBuckets<Key, false, HashMultiSet<Key>>;

    /* =========================================================
        CONSTRUCTORS & SEMI-CONSTRUCTORS
            - CONSTRUCTORS
            - ASSIGN & CLEAR
    ============================================================
        CONSTURCTORS
    --------------------------------------------------------- */
    /**
     * Default Constructor.
     *
     * @param hash An unary function returns hash code. Default is {hash}.
     * @param equal A binary function predicates two arguments are equal. Default is {@link equal_to}.
     */
    public constructor(hash?: Hasher<Key>, equal?: BinaryPredicator<Key>);

    /**
     * Initializer Constructor.
     *
     * @param items Items to assign.
     * @param hash An unary function returns hash code. Default is {hash}.
     * @param equal A binary function predicates two arguments are equal. Default is {@link equal_to}.
     */
    public constructor(
        items: Key[],
        hash?: Hasher<Key>,
        equal?: BinaryPredicator<Key>,
    );

    /**
     * Copy Constructor.
     *
     * @param obj Object to copy.
     */
    public constructor(obj: HashMultiSet<Key>);

    /**
     * Range Constructor.
     *
     * @param first Input iterator of the first position.
     * @param last Input iterator of the last position.
     * @param hash An unary function returns hash code. Default is {hash}.
     * @param equal A binary function predicates two arguments are equal. Default is {@link equal_to}.
     */
    public constructor(
        first: Readonly<IForwardIterator<Key>>,
        last: Readonly<IForwardIterator<Key>>,
        hash?: Hasher<Key>,
        equal?: BinaryPredicator<Key>,
    );

    public constructor(...args: any[]) {
        super((thisArg) => new SetElementList(thisArg));

        IHashContainer.construct<
            Key,
            Key,
            HashMultiSet<Key>,
            HashMultiSet.Iterator<Key>,
            HashMultiSet.ReverseIterator<Key>,
            Key
        >(
            this,
            HashMultiSet,
            (hash, pred) => {
                this.buckets_ = new SetHashBuckets(this, hash, pred);
            },
            ...args,
        );
    }

    /* ---------------------------------------------------------
        ASSIGN & CLEAR
    --------------------------------------------------------- */
    /**
     * @inheritDoc
     */
    public clear(): void {
        this.buckets_.clear();

        super.clear();
    }

    /**
     * @inheritDoc
     */
    public swap(obj: HashMultiSet<Key>): void {
        // SWAP CONTENTS
        [this.data_, obj.data_] = [obj.data_, this.data_];
        SetElementList._Swap_associative(
            this.data_ as Temporary,
            obj.data_ as Temporary,
        );

        // SWAP BUCKETS
        SetHashBuckets._Swap_source(this.buckets_, obj.buckets_);
        [this.buckets_, obj.buckets_] = [obj.buckets_, this.buckets_];
    }

    /* =========================================================
        ACCESSORS
            - MEMBER
            - HASH
    ============================================================
        MEMBER
    --------------------------------------------------------- */
    /**
     * @inheritDoc
     */
    public find(key: Key): HashMultiSet.Iterator<Key> {
        return this.buckets_.find(key);
    }

    /**
     * @inheritDoc
     */
    public count(key: Key): number {
        // FIND MATCHED BUCKET
        const index = this.bucket(key);
        const bucket = this.buckets_.at(index);

        // ITERATE THE BUCKET
        let cnt: number = 0;
        for (let it of bucket) if (this.buckets_.key_eq()(it.value, key)) ++cnt;

        return cnt;
    }

    /**
     * @inheritDoc
     */
    public begin(): HashMultiSet.Iterator<Key>;
    /**
     * @inheritDoc
     */
    public begin(index: number): HashMultiSet.Iterator<Key>;
    public begin(index: number | null = null): HashMultiSet.Iterator<Key> {
        if (index === null) return super.begin();
        else return this.buckets_.at(index)[0];
    }

    /**
     * @inheritDoc
     */
    public end(): HashMultiSet.Iterator<Key>;
    /**
     * @inheritDoc
     */
    public end(index: number): HashMultiSet.Iterator<Key>;
    public end(index: number | null = null): HashMultiSet.Iterator<Key> {
        if (index === null) return super.end();
        else {
            const bucket = this.buckets_.at(index);
            return bucket[bucket.length - 1].next();
        }
    }

    /**
     * @inheritDoc
     */
    public rbegin(): HashMultiSet.ReverseIterator<Key>;
    /**
     * @inheritDoc
     */
    public rbegin(index: number): HashMultiSet.ReverseIterator<Key>;
    public rbegin(
        index: number | null = null,
    ): HashMultiSet.ReverseIterator<Key> {
        return this.end(index!).reverse();
    }

    /**
     * @inheritDoc
     */
    public rend(): HashMultiSet.ReverseIterator<Key>;
    /**
     * @inheritDoc
     */
    public rend(index: number): HashMultiSet.ReverseIterator<Key>;
    public rend(
        index: number | null = null,
    ): HashMultiSet.ReverseIterator<Key> {
        return this.begin(index!).reverse();
    }

    /* ---------------------------------------------------------
        HASH
    --------------------------------------------------------- */
    /**
     * @inheritDoc
     */
    public bucket_count(): number {
        return this.buckets_.length();
    }

    /**
     * @inheritDoc
     */
    public bucket_size(n: number): number {
        return this.buckets_.at(n).length;
    }

    /**
     * @inheritDoc
     */
    public load_factor(): number {
        return this.buckets_.load_factor();
    }

    /**
     * @inheritDoc
     */
    public hash_function(): Hasher<Key> {
        return this.buckets_.hash_function();
    }

    /**
     * @inheritDoc
     */
    public key_eq(): BinaryPredicator<Key> {
        return this.buckets_.key_eq();
    }

    /**
     * @inheritDoc
     */
    public bucket(key: Key): number {
        return this.hash_function()(key) % this.buckets_.length();
    }

    /**
     * @inheritDoc
     */
    public max_load_factor(): number;
    /**
     * @inheritDoc
     */
    public max_load_factor(z: number): void;
    public max_load_factor(z: number | null = null): any {
        return this.buckets_.max_load_factor(z!);
    }

    /**
     * @inheritDoc
     */
    public reserve(n: number): void {
        this.buckets_.rehash(Math.ceil(n * this.max_load_factor()));
    }

    /**
     * @inheritDoc
     */
    public rehash(n: number): void {
        if (n <= this.bucket_count()) return;

        this.buckets_.rehash(n);
    }

    protected _Key_eq(x: Key, y: Key): boolean {
        return this.key_eq()(x, y);
    }

    /* =========================================================
        ELEMENTS I/O
            - INSERT
            - POST-PROCESS
    ============================================================
        INSERT
    --------------------------------------------------------- */
    protected _Insert_by_key(key: Key): HashMultiSet.Iterator<Key> {
        // INSERT
        const it = this.data_.insert(this.data_.end(), key);

        this._Handle_insert(it, it.next()); // POST-PROCESS
        return it;
    }

    protected _Insert_by_hint(
        hint: HashMultiSet.Iterator<Key>,
        key: Key,
    ): HashMultiSet.Iterator<Key> {
        // INSERT
        const it = this.data_.insert(hint, key);

        // POST-PROCESS
        this._Handle_insert(it, it.next());

        return it;
    }

    protected _Insert_by_range<
        InputIterator extends Readonly<IForwardIterator<Key, InputIterator>>,
    >(first: InputIterator, last: InputIterator): void {
        // INSERT ELEMENTS
        const my_first = this.data_.insert(this.data_.end(), first, last);

        // IF NEEDED, HASH_BUCKET TO HAVE SUITABLE SIZE
        if (this.size() > this.buckets_.capacity())
            this.reserve(Math.max(this.size(), this.buckets_.capacity() * 2));

        // POST-PROCESS
        this._Handle_insert(my_first, this.end());
    }

    /* ---------------------------------------------------------
        POST-PROCESS
    --------------------------------------------------------- */
    protected _Handle_insert(
        first: HashMultiSet.Iterator<Key>,
        last: HashMultiSet.Iterator<Key>,
    ): void {
        for (; !first.equals(last); first = first.next())
            this.buckets_.insert(first);
    }

    protected _Handle_erase(
        first: HashMultiSet.Iterator<Key>,
        last: HashMultiSet.Iterator<Key>,
    ): void {
        for (; !first.equals(last); first = first.next())
            this.buckets_.erase(first);
    }
}

/**
 *
 */
export namespace HashMultiSet {
    // HEAD
    /**
     * Iterator of {@link HashMultiSet}
     */
    export type Iterator<Key> = SetElementList.Iterator<
        Key,
        false,
        HashMultiSet<Key>
    >;

    /**
     * Reverse iterator of {@link HashMultiSet}
     */
    export type ReverseIterator<Key> = SetElementList.ReverseIterator<
        Key,
        false,
        HashMultiSet<Key>
    >;

    // BODY
    export const Iterator = SetElementList.Iterator;
    export const ReverseIterator = SetElementList.ReverseIterator;
}