import { getDB } from '$lib/data/db';
import { getAllItems, createItem as dbCreateItem, updateItem as dbUpdateItem, removeItem as dbRemoveItem } from '$lib/data/items';
import { getAllLocations, seedDefaultLocations } from '$lib/data/locations';
import { createSighting } from '$lib/data/sightings';
import { generateItemId, generateSightingId } from '$lib/utils/id';
import { getConfidence } from '$lib/utils/confidence';
import { buildCheckOutUpdate, buildCheckInUpdate } from '$lib/utils/custody';
import type { Item, Location, Sighting, CheckOutReason } from '$lib/types';

class InventoryStore {
	items = $state<Item[]>([]);
	locations = $state<Location[]>([]);
	loading = $state(true);

	checkedOutItems = $derived(
		this.items.filter((i) => i.custodyState === 'checked-out')
	);

	overdueItems = $derived(
		this.items.filter(
			(i) =>
				i.custodyState === 'checked-out' &&
				i.checkedOutSince &&
				Date.now() - new Date(i.checkedOutSince).getTime() > 7 * 86400000
		)
	);

	lowStockItems = $derived(
		this.items.filter(
			(i) =>
				i.currentQuantity != null &&
				i.lowThreshold != null &&
				i.currentQuantity <= i.lowThreshold
		)
	);

	async loadAll() {
		await seedDefaultLocations();
		this.items = await getAllItems();
		this.locations = await getAllLocations();
		this.loading = false;
	}

	async createItem(data: Omit<Item, 'shortId' | 'createdAt' | 'updatedAt' | 'barcodeUri' | 'barcodeFormat'>): Promise<Item> {
		const now = new Date().toISOString();
		const shortId = generateItemId();
		const item: Item = {
			...data,
			shortId,
			barcodeFormat: 'qr',
			barcodeUri: `https://haus.toph.so/${shortId}`,
			createdAt: now,
			updatedAt: now,
		};
		await dbCreateItem(item);
		this.items = [...this.items, item];
		return item;
	}

	async updateItem(shortId: string, updates: Partial<Item>): Promise<Item | undefined> {
		const updated = await dbUpdateItem(shortId, updates);
		if (updated) {
			this.items = this.items.map((i) => (i.shortId === shortId ? updated : i));
		}
		return updated;
	}

	async removeItem(shortId: string): Promise<void> {
		await dbRemoveItem(shortId);
		this.items = this.items.filter((i) => i.shortId !== shortId);
	}

	async checkOut(
		itemId: string,
		reason: CheckOutReason,
		fromLocationId: string,
		toLocationId: string | null = null,
		note: string = ''
	): Promise<void> {
		const updates = buildCheckOutUpdate(reason, fromLocationId, toLocationId, note);
		await this.updateItem(itemId, updates);
	}

	async checkIn(itemId: string, returnToLocationId: string): Promise<void> {
		const updates = buildCheckInUpdate(returnToLocationId);
		await this.updateItem(itemId, updates);
	}

	async recordSighting(
		itemId: string,
		locationId: string,
		type: 'scan' | 'manual' | 'camera-detect' | 'audit-verify' = 'scan'
	): Promise<void> {
		const now = new Date().toISOString();
		const sighting: Sighting = {
			id: generateSightingId(),
			itemId,
			locationId,
			timestamp: now,
			sightingType: type,
			confidence: 'confirmed',
			notes: '',
			createdBy: null,
		};
		await createSighting(sighting);
		await this.updateItem(itemId, {
			lastSeenAt: locationId,
			lastSeenTimestamp: now,
			locationConfidence: 'confirmed',
		});
	}

	getItemsByLocation(locationId: string): Item[] {
		return this.items.filter((i) => i.lastSeenAt === locationId);
	}

	getLocationTree(): Map<string | null, Location[]> {
		const tree = new Map<string | null, Location[]>();
		for (const loc of this.locations) {
			const children = tree.get(loc.parentId) ?? [];
			children.push(loc);
			tree.set(loc.parentId, children);
		}
		return tree;
	}
}

export const inventory = new InventoryStore();