/*
 * *****************************************************************************
 * Copyright (C) National University of Quilmes 2018-2024
 * Gobstones (TM) is a trademark of the National University of Quilmes.
 *
 * This program is free software distributed under the terms of the
 * GNU Affero General Public License version 3.
 * Additional terms added in compliance to section 7 of such license apply.
 *
 * You may read the full license at https://gobstones.github.io/gobstones-guidelines/LICENSE.
 * *****************************************************************************
 */

/**
 * @module SourceReader/SourcePositions
 * @author Alan Rodas Bonjour <alanrodas@gmail.com>
 */
import { AbstractDocumentSourcePosition } from './AbstractDocumentSourcePosition';

import { SourcePosition } from '../SourcePosition';
import { SourceReader } from '../SourceReader';

/**
 * An {@link EndOfDocumentSourcePosition} points to a position that is right
 * after the last character in a specific document of a {@link SourceReader}.
 * That position is reached when all characters in the current input document
 * have been processed, but the source reader has not yet been advanced to the
 * next document.
 * It is a special position, because it does not point to a particular position
 * inside a document in the source input, but to the end of one of the documents in it.
 */
export class EndOfDocumentSourcePosition extends AbstractDocumentSourcePosition implements SourcePosition {
    /**
     * @inheritdoc
     */
    public readonly isEndOfDocument: boolean = true;

    /**
     * Constructs an end of document position in an input source.
     * It is intended to be used only by {@link SourceReader}.
     *
     * **PRECONDITIONS:** (not verified during execution)
     *  * all numbers are >= 0
     *  * numbers are consistent with the reader state
     *
     * @param sourceReader - The {@link SourceReader} of the input this position belongs to.
     * @param line - The line number of this position in the current input.
     *      It will be modified only by the constructor.
     *      **INVARIANT:** `line >=1`, and it is a valid line in that reader.
     * @param column - The column number of this position in the current input.
     *      It will be modified only by the constructor.
     *      **INVARIANT:** `column >= 1` and it is a valid column in that reader.
     * @param regions - The regions the position in the current input belongs to.
     *      It will be modified only by the constructor.
     *      **INVARIANT:** the regions are valid in the position's reader.
     * @param documentIndex - The index with information about the input document
     *      in the `_sourceReader`. **INVARIANT**: `documentIndex >= 0` and it
     *      is a valid index in that reader.
     * @param charIndex - The index with information about the exact char pointed
     *      to by this position in the input document. **INVARIANT:**
     *      `charIndex >= 0` and it is a valid index in that reader.
     * @param visibleCharIndex - The index with information about the exact char
     *      pointed to by this position in the visible input document.
     *      **INVARIANT:** `visibleCharIndex >= 0` and it is a valid index in
     *      that reader.
     */
    public constructor(
        sourceReader: SourceReader,
        line: number,
        column: number,
        regions: string[],
        documentIndex: number,
        charIndex: number,
        visibleCharIndex: number
    ) {
        super(sourceReader, line, column, regions, documentIndex, charIndex, visibleCharIndex);
    }

    /**
     * @inheritdoc
     */
    public toString(): string {
        return '@<EOD>';
    }

    /**
     * @inheritdoc
     */
    protected _documentContextBefore(lines: number): string[] {
        return this.sourceReader._documentContextBeforeOf(
            this._internalDocumentIndex(),
            this._internalCharacterIndex(false),
            lines
        );
    }

    /**
     * @inheritdoc
     */
    protected _documentContextAfter(_lines: number): string[] {
        return [''];
    }
}