42 lines
1.5 KiB
TypeScript
42 lines
1.5 KiB
TypeScript
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import type { ItemId, StoreItem } from "@/app/types";
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import { CATALOG } from "./catalog";
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// ---------------------------------------------------------------------------
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// PriceProvider: the single seam between "where prices come from" and the
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// rest of the app. The cost math only ever calls `getItem`.
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//
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// To use live retailer prices later:
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// 1. Fetch prices on the SERVER (a Server Action or route handler) so the
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// API key never reaches the browser.
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// 2. Build a snapshot `StoreItem[]` from the response.
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// 3. Pass `new SnapshotPriceProvider("Live grocery prices", snapshot)` into
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// the grocery/planner functions instead of `averageGroceryProvider`.
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// The math stays synchronous and testable because it works on a snapshot.
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// ---------------------------------------------------------------------------
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export interface PriceProvider {
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/** Shown in the UI so users know where prices came from. */
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readonly label: string;
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getItem(id: ItemId): StoreItem | undefined;
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}
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export class SnapshotPriceProvider implements PriceProvider {
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private readonly byId: Map<ItemId, StoreItem>;
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constructor(
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readonly label: string,
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items: StoreItem[],
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) {
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this.byId = new Map(items.map((item) => [item.id, item]));
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}
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getItem(id: ItemId): StoreItem | undefined {
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return this.byId.get(id);
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}
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}
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export const averageGroceryProvider: PriceProvider = new SnapshotPriceProvider(
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"Based on average grocery prices as of October 2026",
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CATALOG,
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);
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