//================================================================
/**
 * @packageDocumentation
 * @module std.internal
 */
//================================================================
import { IContainer } from "../../base/container/IContainer";
import { ReverseIterator } from "./ReverseIterator";

import { ErrorGenerator } from "../exception/ErrorGenerator";

/**
 * Basic List Iterator.
 *
 * @author Jeongho Nam - https://github.com/samchon
 */
export abstract class ListIterator<
    T extends Elem,
    SourceT extends IContainer<T, SourceT, IteratorT, ReverseIteratorT, Elem>,
    IteratorT extends ListIterator<
        T,
        SourceT,
        IteratorT,
        ReverseIteratorT,
        Elem
    >,
    ReverseIteratorT extends ReverseIterator<
        T,
        SourceT,
        IteratorT,
        ReverseIteratorT,
        Elem
    >,
    Elem,
> implements
        Readonly<
            IContainer.Iterator<T, SourceT, IteratorT, ReverseIteratorT, Elem>
        >
{
    private prev_: IteratorT;
    private next_: IteratorT;
    protected value_: T;

    /**
     * @internal
     */
    public erased_?: boolean;

    /* ---------------------------------------------------------------
        CONSTRUCTORS
    --------------------------------------------------------------- */
    protected constructor(prev: IteratorT, next: IteratorT, value: T) {
        this.prev_ = prev;
        this.next_ = next;
        this.value_ = value;
    }

    /**
     * @inheritDoc
     */
    public abstract reverse(): ReverseIteratorT;

    /**
     * @internal
     */
    public static _Set_prev<
        T extends Elem,
        SourceT extends IContainer<
            T,
            SourceT,
            IteratorT,
            ReverseIteratorT,
            Elem
        >,
        IteratorT extends ListIterator<
            T,
            SourceT,
            IteratorT,
            ReverseIteratorT,
            Elem
        >,
        ReverseIteratorT extends ReverseIterator<
            T,
            SourceT,
            IteratorT,
            ReverseIteratorT,
            Elem
        >,
        Elem,
    >(it: IteratorT, prev: IteratorT): void {
        it.prev_ = prev;
    }

    /**
     * @internal
     */
    public static _Set_next<
        T extends Elem,
        SourceT extends IContainer<
            T,
            SourceT,
            IteratorT,
            ReverseIteratorT,
            Elem
        >,
        IteratorT extends ListIterator<
            T,
            SourceT,
            IteratorT,
            ReverseIteratorT,
            Elem
        >,
        ReverseIteratorT extends ReverseIterator<
            T,
            SourceT,
            IteratorT,
            ReverseIteratorT,
            Elem
        >,
        Elem,
    >(it: IteratorT, next: IteratorT): void {
        it.next_ = next;
    }

    /* ---------------------------------------------------------------
        ACCESSORS
    --------------------------------------------------------------- */
    /**
     * @inheritDoc
     */
    public abstract source(): SourceT;

    /**
     * @inheritDoc
     */
    public prev(): IteratorT {
        return this.prev_;
    }

    /**
     * @inheritDoc
     */
    public next(): IteratorT {
        return this.next_;
    }

    /**
     * @inheritDoc
     */
    public get value(): T {
        this._Try_value();
        return this.value_;
    }

    protected _Try_value(): void {
        if (
            this.value_ === undefined &&
            this.equals(this.source().end()) === true
        )
            throw ErrorGenerator.iterator_end_value(this.source());
    }

    /* ---------------------------------------------------------------
        COMPARISON
    --------------------------------------------------------------- */
    /**
     * @inheritDoc
     */
    public equals(obj: IteratorT): boolean {
        return this === <any>obj;
    }
}