import type { SearchHit } from '$lib/server/recipes/search-local';
import type { WebHit } from '$lib/server/search/searxng';

export type SearchSnapshot = {
  query: string;
  hits: SearchHit[];
  webHits: WebHit[];
  searchedFor: string | null;
  webError: string | null;
  localExhausted: boolean;
  webPageno: number;
  webExhausted: boolean;
};

export type SearchStoreOptions = {
  pageSize?: number;
  debounceMs?: number;
  filterDebounceMs?: number;
  minQueryLength?: number;
  filterParam?: () => string;
  fetchImpl?: typeof fetch;
};

export class SearchStore {
  query = $state('');
  hits = $state<SearchHit[]>([]);
  webHits = $state<WebHit[]>([]);
  searching = $state(false);
  webSearching = $state(false);
  webError = $state<string | null>(null);
  searchedFor = $state<string | null>(null);
  localExhausted = $state(false);
  webPageno = $state(0);
  webExhausted = $state(false);
  loadingMore = $state(false);

  private readonly pageSize: number;
  private readonly debounceMs: number;
  private readonly filterDebounceMs: number;
  private readonly minQueryLength: number;
  private readonly filterParam: () => string;
  private readonly fetchImpl: typeof fetch;
  private debounceTimer: ReturnType<typeof setTimeout> | null = null;
  private skipNextDebounce = false;

  constructor(opts: SearchStoreOptions = {}) {
    this.pageSize = opts.pageSize ?? 30;
    this.debounceMs = opts.debounceMs ?? 300;
    this.filterDebounceMs = opts.filterDebounceMs ?? 150;
    this.minQueryLength = opts.minQueryLength ?? 4;
    this.filterParam = opts.filterParam ?? (() => '');
    this.fetchImpl = opts.fetchImpl ?? ((...a) => fetch(...a));
  }

  runDebounced(): void {
    if (this.debounceTimer) clearTimeout(this.debounceTimer);
    if (this.skipNextDebounce) {
      this.skipNextDebounce = false;
      return;
    }
    const q = this.query.trim();
    if (q.length < this.minQueryLength) {
      this.resetResults();
      return;
    }
    this.searching = true;
    this.webHits = [];
    this.webSearching = false;
    this.webError = null;
    this.debounceTimer = setTimeout(() => {
      void this.runSearch(q);
    }, this.debounceMs);
  }

  async runSearch(q: string): Promise<void> {
    if (this.debounceTimer) clearTimeout(this.debounceTimer);
    this.debounceTimer = null;
    this.localExhausted = false;
    this.webPageno = 0;
    this.webExhausted = false;
    try {
      const res = await this.fetchImpl(
        `/api/recipes/search?q=${encodeURIComponent(q)}&limit=${this.pageSize}${this.filterParam()}`
      );
      const body = (await res.json()) as { hits: SearchHit[] };
      if (this.query.trim() !== q) return;
      this.hits = body.hits;
      this.searchedFor = q;
      if (this.hits.length < this.pageSize) this.localExhausted = true;
      if (this.hits.length === 0) {
        await this.runWebSearch(q, 1);
      }
    } finally {
      if (this.query.trim() === q) this.searching = false;
    }
  }

  private async runWebSearch(q: string, pageno: number): Promise<void> {
    this.webSearching = true;
    try {
      const res = await this.fetchImpl(
        `/api/recipes/search/web?q=${encodeURIComponent(q)}&pageno=${pageno}${this.filterParam()}`
      );
      if (this.query.trim() !== q) return;
      if (!res.ok) {
        const err = (await res.json().catch(() => ({}))) as { message?: string };
        this.webError = err.message ?? `HTTP ${res.status}`;
        this.webExhausted = true;
        return;
      }
      const body = (await res.json()) as { hits: WebHit[] };
      this.webHits = pageno === 1 ? body.hits : [...this.webHits, ...body.hits];
      this.webPageno = pageno;
      if (body.hits.length === 0) this.webExhausted = true;
    } finally {
      if (this.query.trim() === q) this.webSearching = false;
    }
  }

  async loadMore(): Promise<void> {
    if (this.loadingMore) return;
    const q = this.query.trim();
    if (!q) return;
    this.loadingMore = true;
    try {
      if (!this.localExhausted) {
        const res = await this.fetchImpl(
          `/api/recipes/search?q=${encodeURIComponent(q)}&limit=${this.pageSize}&offset=${this.hits.length}${this.filterParam()}`
        );
        const body = (await res.json()) as { hits: SearchHit[] };
        if (this.query.trim() !== q) return;
        const more = body.hits;
        const seen = new Set(this.hits.map((h) => h.id));
        const deduped = more.filter((h) => !seen.has(h.id));
        this.hits = [...this.hits, ...deduped];
        if (more.length < this.pageSize) this.localExhausted = true;
      } else if (!this.webExhausted) {
        const nextPage = this.webPageno + 1;
        const wasEmpty = this.webHits.length === 0;
        if (wasEmpty) this.webSearching = true;
        try {
          const res = await this.fetchImpl(
            `/api/recipes/search/web?q=${encodeURIComponent(q)}&pageno=${nextPage}${this.filterParam()}`
          );
          if (this.query.trim() !== q) return;
          if (!res.ok) {
            const err = (await res.json().catch(() => ({}))) as { message?: string };
            this.webError = err.message ?? `HTTP ${res.status}`;
            this.webExhausted = true;
            return;
          }
          const body = (await res.json()) as { hits: WebHit[] };
          const more = body.hits;
          const seen = new Set(this.webHits.map((h) => h.url));
          const deduped = more.filter((h) => !seen.has(h.url));
          if (deduped.length === 0) {
            this.webExhausted = true;
          } else {
            this.webHits = [...this.webHits, ...deduped];
            this.webPageno = nextPage;
          }
        } finally {
          if (this.query.trim() === q) this.webSearching = false;
        }
      }
    } finally {
      this.loadingMore = false;
    }
  }

  reSearch(): void {
    const q = this.query.trim();
    if (q.length < this.minQueryLength) return;
    if (this.debounceTimer) clearTimeout(this.debounceTimer);
    this.searching = true;
    this.webHits = [];
    this.webSearching = false;
    this.webError = null;
    this.debounceTimer = setTimeout(() => void this.runSearch(q), this.filterDebounceMs);
  }

  reset(): void {
    if (this.debounceTimer) clearTimeout(this.debounceTimer);
    this.debounceTimer = null;
    this.query = '';
    this.resetResults();
  }

  private resetResults(): void {
    this.hits = [];
    this.webHits = [];
    this.searchedFor = null;
    this.searching = false;
    this.webSearching = false;
    this.webError = null;
    this.localExhausted = false;
    this.webPageno = 0;
    this.webExhausted = false;
  }

  captureSnapshot(): SearchSnapshot {
    return {
      query: this.query,
      hits: this.hits,
      webHits: this.webHits,
      searchedFor: this.searchedFor,
      webError: this.webError,
      localExhausted: this.localExhausted,
      webPageno: this.webPageno,
      webExhausted: this.webExhausted
    };
  }

  restoreSnapshot(s: SearchSnapshot): void {
    this.skipNextDebounce = true;
    this.query = s.query;
    this.hits = s.hits;
    this.webHits = s.webHits;
    this.searchedFor = s.searchedFor;
    this.webError = s.webError;
    this.localExhausted = s.localExhausted;
    this.webPageno = s.webPageno;
    this.webExhausted = s.webExhausted;
  }
}