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

import { MapElementList } from "../internal/container/associative/MapElementList";
import { MapHashBuckets } from "../internal/hash/MapHashBuckets";

import { NativeArrayIterator } from "../internal/iterator/disposable/NativeArrayIterator";
import { IForwardIterator } from "../iterator/IForwardIterator";
import { IPair } from "../utility/IPair";
import { Entry } from "../utility/Entry";

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

/**
 * Multiple-key Map based on Hash buckets.
 *
 * @author Jeongho Nam - https://github.com/samchon
 */
export class HashMultiMap<Key, T>
    extends MultiMap<
        Key,
        T,
        HashMultiMap<Key, T>,
        HashMultiMap.Iterator<Key, T>,
        HashMultiMap.ReverseIterator<Key, T>
    >
    implements IHashMap<Key, T, false, HashMultiMap<Key, T>>
{
    private buckets_!: MapHashBuckets<Key, T, false, HashMultiMap<Key, T>>;

    /* =========================================================
        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: IPair<Key, T>[],
        hash?: Hasher<Key>,
        equal?: BinaryPredicator<Key>,
    );

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

    /**
     * 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<IPair<Key, T>>>,
        last: Readonly<IForwardIterator<IPair<Key, T>>>,
        hash?: Hasher<Key>,
        equal?: BinaryPredicator<Key>,
    );

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

        IHashContainer.construct<
            Key,
            Entry<Key, T>,
            HashMultiMap<Key, T>,
            HashMultiMap.Iterator<Key, T>,
            HashMultiMap.ReverseIterator<Key, T>,
            IPair<Key, T>
        >(
            this,
            HashMultiMap,
            (hash, pred) => {
                this.buckets_ = new MapHashBuckets(
                    this as HashMultiMap<Key, T>,
                    hash,
                    pred,
                );
            },
            ...args,
        );
    }

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

        super.clear();
    }

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

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

    /* =========================================================
        ACCESSORS
            - MEMBER
            - HASH
    ============================================================
        MEMBER
    --------------------------------------------------------- */
    /**
     * @inheritDoc
     */
    public find(key: Key): HashMultiMap.Iterator<Key, T> {
        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.first, key)) ++cnt;

        return cnt;
    }

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

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

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

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

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

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

    /**
     * @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
    --------------------------------------------------------- */
    /**
     * @inheritDoc
     */
    public emplace(key: Key, val: T): HashMultiMap.Iterator<Key, T> {
        // INSERT
        const it = this.data_.insert(this.data_.end(), new Entry(key, val));

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

    /**
     * @inheritDoc
     */
    public emplace_hint(
        hint: HashMultiMap.Iterator<Key, T>,
        key: Key,
        val: T,
    ): HashMultiMap.Iterator<Key, T> {
        // INSERT
        const it = this.data_.insert(hint, new Entry(key, val));

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

        return it;
    }

    protected _Insert_by_range<
        InputIterator extends Readonly<
            IForwardIterator<IPair<Key, T>, InputIterator>
        >,
    >(first: InputIterator, last: InputIterator): void {
        //--------
        // INSERTIONS
        //--------
        // PRELIMINARIES
        const entries: Array<Entry<Key, T>> = [];
        for (let it = first; !it.equals(last); it = it.next())
            entries.push(new Entry(it.value.first, it.value.second));

        // INSERT ELEMENTS
        const my_first = this.data_.insert(
            this.data_.end(),
            new NativeArrayIterator(entries, 0),
            new NativeArrayIterator(entries, entries.length),
        );

        //--------
        // HASHING INSERTED ITEMS
        //--------
        // 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: HashMultiMap.Iterator<Key, T>,
        last: HashMultiMap.Iterator<Key, T>,
    ): void {
        for (; !first.equals(last); first = first.next())
            this.buckets_.insert(first);
    }

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

/**
 *
 */
export namespace HashMultiMap {
    //----
    // PASCAL NOTATION
    //----
    // HEAD
    /**
     * Iterator of {@link HashMultiMap}
     */
    export type Iterator<Key, T> = MapElementList.Iterator<
        Key,
        T,
        false,
        HashMultiMap<Key, T>
    >;

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

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