import { Parser, ParsingContext } from "../../chrono";
import { ParsingComponents, ParsingResult } from "../../results";
import { Component } from "../../index";

/**
 *
 */
export abstract class AbstractParserWithWordBoundaryChecking implements Parser {
    abstract innerPattern(context: ParsingContext): RegExp;
    abstract innerExtract(
        context: ParsingContext,
        match: RegExpMatchArray
    ): ParsingComponents | ParsingResult | { [c in Component]?: number } | null;

    private cachedInnerPattern?: RegExp = null;
    private cachedPattern?: RegExp = null;

    pattern(context: ParsingContext): RegExp {
        const innerPattern = this.innerPattern(context);
        if (innerPattern == this.cachedInnerPattern) {
            return this.cachedPattern;
        }

        this.cachedPattern = new RegExp(`(\\W|^)${innerPattern.source}`, innerPattern.flags);
        this.cachedInnerPattern = innerPattern;
        return this.cachedPattern;
    }

    extract(context: ParsingContext, match: RegExpMatchArray) {
        const header = match[1] ?? "";
        match.index = match.index + header.length;
        match[0] = match[0].substring(header.length);
        for (let i = 2; i < match.length; i++) {
            match[i - 1] = match[i];
        }

        return this.innerExtract(context, match);
    }
}