pashto-inflector/src/lib/get-english-word.ts

import * as T from "../types";

/**
 * returns the singular and plural english word for a Pashto entry if possible
 * NOTE: only works with nouns and adjectives
 * 
 * @param entry dictionary entry
 * @returns undefined if not possible, string for adjective, { singular?: string, plural: string } for noun 
 */
export function getEnglishWord(entry: T.DictionaryEntry): {
    singular?: string,
    plural: string,
} | string | undefined {
    if (!entry.c) return undefined;
    const isNoun = entry.c.includes("n.");
    const isAdj = entry.c.includes("adj.");
    const isAdv = entry.c.includes("adv.");
    if (!isNoun && !isAdj && !isAdv) return undefined;
    const base = entry.e.split(",")[0].split(";")[0].split("(")[0].trim();
    if ((isAdj || isAdv) && !isNoun) {
        return base;
    }
    if (entry.ec && entry.ep) {
        return {
            singular: entry.ec,
            plural: entry.ep,
        };
    }
    if (entry.c.includes("pl.")) {
        return {
            plural: base,
        };
    }
    if (base.slice(-3) === "sis") {
        return {
            singular: base,
            plural: `${base.slice(0, -2)}es`,
        };
    }
    if (
        ["sh", "ch"].includes(base.slice(-2)) ||
        ["s", "x", "z", "o"].includes(base.slice(-1))
    ) {
        return {
            singular: base,
            plural: `${base}es`,
        };
    }
    if (base.slice(-1) === "y" && !isVowel(base.slice(-2, -1))) {
        return {
            singular: base,
            plural: `${base.slice(0, -1)}ies`,
        };
    }
    return {
        singular: base,
        plural: `${base}s`,
    };
}

function isVowel(l: string): boolean {
    return ["a", "e", "i", "o", "u"].includes(l);
}