import { WORD_BOUNDARY } from "../constants/text-processing";
// Sentence detection thresholds
const MAX_KEYWORDS_WITH_DELIMITERS = 20;
const MAX_SPACE_SEPARATED_WORDS = 4;
const MAX_TOKENS_WITHOUT_DELIMITERS = 6;
export class KeywordParser {
parse(raw: string): string[] {
if (!raw || raw.trim().length === 0) {
throw new Error("Keyword input must not be empty.");
}
const keywords = raw.split(/[\n,]/u).flatMap((segment) =>
segment
.split(WORD_BOUNDARY)
.map((token) => token.trim().toLowerCase())
.filter(Boolean),
);
if (keywords.length === 0) {
throw new Error("Keyword input must not be empty.");
}
if (this.containsSentence(raw, keywords)) {
throw new Error(
"Keyword input must be provided as short keywords, not full sentences.",
);
}
return Array.from(new Set(keywords));
}
private containsSentence(raw: string, tokens: string[]): boolean {
const hasDelimiter = /[,;\n]/u.test(raw);
const spaceSeparated = raw.trim().split(/\s+/u);
const includesStopWord = tokens.some((token) => STOP_WORDS.has(token));
// Early return: stop words indicate a sentence
if (includesStopWord) {
return true;
}
// If delimiters are present, allow many keywords (up to 20)
// This supports comma-separated keyword lists like "summer, sun, beach, ocean"
if (hasDelimiter) {
return tokens.length > MAX_KEYWORDS_WITH_DELIMITERS;
}
// Without delimiters, be more strict to detect sentences
// Space-separated input with 4+ words or 6+ tokens is likely a sentence
return (
spaceSeparated.length >= MAX_SPACE_SEPARATED_WORDS ||
tokens.length >= MAX_TOKENS_WITHOUT_DELIMITERS
);
}
}
const STOP_WORDS = new Set([
"about",
"for",
"from",
"have",
"here",
"icon",
"icons",
"please",
"show",
"tell",
"that",
"the",
"what",
"with",
]);
