"use strict";

function copy(value) {
  return value === undefined ? undefined : JSON.parse(JSON.stringify(value));
}

function normalizeConceptName(value) {
  return String(value || "").trim().toLocaleLowerCase();
}

/** Index lightweight concept placements across stored CMaps. */
export class CmapReferenceIndex {
  constructor() {
    this.byConceptId = new Map();
    this.byName = new Map();
    this.byPage = new Map();
  }

  clear() {
    this.byConceptId.clear();
    this.byName.clear();
    this.byPage.clear();
  }

  load(placements = [], conceptMaps = [], canonicalPageReference = (value) => value,
    normalizeName = normalizeConceptName) {
    this.clear();
    const mapTitles = new Map(conceptMaps
      .filter((map) => map && map.slug)
      .map((map) => [map.slug, map.title || map.slug]));
    const pageByConcept = new Map();
    for (const placement of placements) {
      if (!placement?.conceptId || !placement.pageSlug) continue;
      pageByConcept.set(placement.conceptId,
        canonicalPageReference(placement.pageSlug).toLocaleLowerCase());
    }
    for (const placement of placements) {
      if (!placement?.conceptId || !placement.cmapSlug) continue;
      const conceptId = String(placement.conceptId);
      const slug = String(placement.cmapSlug);
      const nameKey = normalizeName(placement.label);
      if (nameKey) this.byName.set(nameKey, conceptId);
      if (!this.byConceptId.has(conceptId)) this.byConceptId.set(conceptId, new Map());
      const maps = this.byConceptId.get(conceptId);
      const existing = maps.get(slug);
      maps.set(slug, {
        slug,
        title: mapTitles.get(slug) || placement.cmapTitle || slug,
        count: (existing?.count || 0) + (Number(placement.count) || 0)
      });

      const pageKey = pageByConcept.get(conceptId);
      if (!pageKey) continue;
      if (!this.byPage.has(pageKey)) this.byPage.set(pageKey, new Map());
      const pageConcepts = this.byPage.get(pageKey);
      if (!pageConcepts.has(conceptId)) {
        pageConcepts.set(conceptId, {
          conceptId,
          label: placement.label || "Concept",
          count: 0,
          maps: new Map()
        });
      }
      const concept = pageConcepts.get(conceptId);
      const count = Number(placement.count) || 0;
      concept.count += count;
      const pageMap = concept.maps.get(slug);
      concept.maps.set(slug, {
        slug,
        title: mapTitles.get(slug) || placement.cmapTitle || slug,
        count: count + (pageMap?.count || 0)
      });
    }
    return this;
  }

  mapsFor(conceptId) {
    return Array.from(this.byConceptId.get(String(conceptId))?.values() || [])
      .map(copy);
  }

  countFor(conceptId) {
    return this.mapsFor(conceptId).reduce((sum, map) => sum + map.count, 0);
  }

  conceptIdForName(label) {
    return this.byName.get(normalizeConceptName(label)) || null;
  }

  pageConcepts(pageReference) {
    return Array.from(this.byPage.get(String(pageReference).toLocaleLowerCase())?.values() || [])
      .map((concept) => ({ ...copy(concept), maps: new Map(concept.maps) }));
  }
}