import type { ParsedNaturalLanguageRequest, ProductFilters } from "./types.js";

function cleanQuery(text: string): string {
  return text
    .replace(/\breview score of\b/gi, " ")
    .replace(/\brating of\b/gi, " ")
    .replace(/\b(?:delivery|shipping)\s+only\b/gi, " ")
    .replace(/\blow\s+to\s+high\b/gi, " ")
    .replace(/\bhigh\s+to\s+low\b/gi, " ")
    .replace(/\bof\s+in\s+width\b/gi, " ")
    .replace(/\bin\s+width\b/gi, " ")
    .replace(/\b(?:that|and|with|have)\b/gi, " ")
    .replace(/[,\s]+/g, " ")
    .replace(/\s+/g, " ")
    .replace(/\s+(and|or|a)$/i, "")
    .trim();
}

function removeMatched(text: string, match: RegExpMatchArray | null): string {
  if (!match) {
    return text;
  }
  return text.replace(match[0], " ");
}

export function parseNaturalLanguageRequest(input: string): ParsedNaturalLanguageRequest {
  let remaining = input.trim();
  const filters: ProductFilters = {
    includeKeywords: [],
    excludeKeywords: []
  };
  let limit: number | undefined;

  const limitMatch = remaining.match(/\b(?:return|limit|top)\s+(\d{1,3})\b/i);
  if (limitMatch) {
    limit = Number(limitMatch[1]);
    remaining = removeMatched(remaining, limitMatch);
  }

  const sortByPriceMatch = remaining.match(/\b(?:by price|sort(?:ed)? by price|lowest price|cheapest|least expensive)\b/i);
  if (sortByPriceMatch) {
    filters.sortBy = "price";
    remaining = removeMatched(remaining, sortByPriceMatch);
  }

  const deliveryTomorrowMatch = remaining.match(/\b(?:delivery|delivered|arrives?|shipping|ships?)\s+(?:by\s+)?tomorrow\b/i);
  const deliveryTodayMatch = remaining.match(/\b(?:delivery|delivered|arrives?|shipping|ships?)\s+(?:by\s+)?today\b/i)
    ?? remaining.match(/\bsame[- ]day\s+(?:delivery|shipping)\b/i);
  const overnightMatch = remaining.match(/\bovernight\s+(?:delivery|shipping)\b/i)
    ?? remaining.match(/\bnext[- ]day\s+(?:delivery|shipping)\b/i);
  const deliveryMatch = overnightMatch ?? deliveryTomorrowMatch ?? deliveryTodayMatch;
  if (deliveryMatch) {
    filters.deliveryBy = overnightMatch ? "overnight" : deliveryTomorrowMatch ? "tomorrow" : "today";
    remaining = removeMatched(remaining, deliveryMatch);
  }

  const primeMatch = remaining.match(/\b(?:(?:shipped|ships|shipping|delivery|delivered)\s+(?:with|by|from)\s+)?prime\b/i);
  if (primeMatch) {
    filters.requirePrime = true;
    remaining = removeMatched(remaining, primeMatch);
  }

  const widthMatch = remaining.match(/\b(?:width\s*(?:of\s*)?)?([0-9]+(?:\.[0-9]+)?)\s*(?:inches|inch|in\.?|")\s*(?:or\s+)?(?:wider|wide|larger|longer)\b/i)
    ?? remaining.match(/\b([0-9]+(?:\.[0-9]+)?)\s*(?:inches|inch|in\.?|")\s*(?:or\s+)?(?:wider|wide|larger|longer)\s+(?:in\s+)?width\b/i)
    ?? remaining.match(/\b(?:at least|minimum|min\.?)\s+([0-9]+(?:\.[0-9]+)?)\s*(?:inches|inch|in\.?|")\s+(?:wide|width)\b/i);
  if (widthMatch) {
    filters.minWidthInches = Number(widthMatch[1]);
    filters.widthComparison = "gte";
    remaining = removeMatched(remaining, widthMatch);
  }

  const unitPriceMatch = remaining.match(/\b(?:cost\s+)?(?:less than|under|below)\s+\$([0-9]+(?:\.[0-9]{1,2})?)\s*(?:each|per\b|\/\s*(?:count|unit|item))\b/i);
  if (unitPriceMatch) {
    filters.maxUnitPrice = Number(unitPriceMatch[1]);
    remaining = removeMatched(remaining, unitPriceMatch);
  }

  const maxPriceMatch = remaining.match(/\b(?:cost\s+)?(?:less than|under|below)\s+\$([0-9]+(?:\.[0-9]{1,2})?)\b/i);
  if (maxPriceMatch) {
    filters.maxPrice = Number(maxPriceMatch[1]);
    remaining = removeMatched(remaining, maxPriceMatch);
  }

  const exclusiveReviews = remaining.match(/\b(?:over|more than|above)\s+([0-9][0-9,]*)\s*(?:reviews?|ratings?)\b/i);
  const inclusiveReviews = remaining.match(/\b(?:at least|minimum|min\.?)\s+([0-9][0-9,]*)\s*(?:reviews?|ratings?)\b/i)
    ?? remaining.match(/\b([0-9][0-9,]*)\s*\+\s*(?:reviews?|ratings?)\b/i);
  const reviewMatch = exclusiveReviews ?? inclusiveReviews;
  if (reviewMatch) {
    filters.minReviews = Number(reviewMatch[1].replace(/,/g, ""));
    filters.reviewCountComparison = exclusiveReviews ? "gt" : "gte";
    remaining = removeMatched(remaining, reviewMatch);
  }

  const exclusiveRating = remaining.match(/\b(?:a\s+)?(?:(?:review score|rating)\s+of\s+|rating\s+)?(?:more than|over|above|rated above)\s+([0-5](?:\.[0-9])?)\s*(?:stars?)?\b/i);
  const inclusiveRating = remaining.match(/\b(?:a\s+)?(?:review score|rating)(?:\s+of)?\s+([0-5](?:\.[0-9])?)\s*(?:stars?)?\s+(?:or|and)\s+(?:higher|better)\b/i)
    ?? remaining.match(/\b([0-5](?:\.[0-9])?)\s*stars?\s+or\s+better\b/i)
    ?? remaining.match(/\b([0-5](?:\.[0-9])?)\s*stars?\s+(?:or|and)\s+(?:higher|better)\b/i)
    ?? remaining.match(/\b(?:at least|minimum|min\.?)\s+([0-5](?:\.[0-9])?)\s*(?:stars?|rating)?\b/i);
  const ratingMatch = exclusiveRating ?? inclusiveRating;
  if (ratingMatch) {
    filters.minRating = Number(ratingMatch[1]);
    filters.ratingComparison = exclusiveRating ? "gt" : "gte";
    remaining = removeMatched(remaining, ratingMatch);
  }

  return {
    query: cleanQuery(remaining),
    filters,
    limit
  };
}