type Snapshot = {
  recipes: { recipe_id: number }[];
  uncheckedCount: number;
};

export class ShoppingCartStore {
  uncheckedCount = $state(0);
  recipeIds = $state<Set<number>>(new Set());
  loaded = $state(false);

  private readonly fetchImpl: typeof fetch;

  constructor(fetchImpl?: typeof fetch) {
    this.fetchImpl = fetchImpl ?? ((...a) => fetch(...a));
  }

  async refresh(): Promise<void> {
    try {
      const res = await this.fetchImpl('/api/shopping-list');
      if (!res.ok) return;
      const body = (await res.json()) as Snapshot;
      this.recipeIds = new Set(body.recipes.map((r) => r.recipe_id));
      this.uncheckedCount = body.uncheckedCount;
      this.loaded = true;
    } catch {
      // keep last known state on network error
    }
  }

  async addRecipe(recipeId: number): Promise<void> {
    const res = await this.fetchImpl('/api/shopping-list/recipe', {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify({ recipe_id: recipeId })
    });
    // Consume body to avoid leaking response, even if we ignore the payload.
    await res.json().catch(() => null);
    await this.refresh();
  }

  async removeRecipe(recipeId: number): Promise<void> {
    const res = await this.fetchImpl(`/api/shopping-list/recipe/${recipeId}`, { method: 'DELETE' });
    await res.json().catch(() => null);
    await this.refresh();
  }

  isInCart(recipeId: number): boolean {
    return this.recipeIds.has(recipeId);
  }
}

export const shoppingCartStore = new ShoppingCartStore();