import { pb } from '$lib/pocketbase';
import type { ChatMessage, TypingRow } from '$lib/types';

interface ChatInit {
	famId: string;
	actorId: string;
	actorType: 'admin' | 'member';
	actorName: string;
	actorColor: string;
	deviceToken?: string;
	memberId?: string;
}

class ChatStore {
	famId = $state('');
	messages = $state<ChatMessage[]>([]);
	typing = $state<Record<string, TypingRow>>({});
	unread = $state(0);
	open = $state(false);
	initialized = $state(false);

	actorId = $state('');
	actorType = $state<'admin' | 'member'>('member');
	actorName = $state('');
	actorColor = $state('');
	deviceToken = $state('');
	memberId = $state('');

	private unsubs: (() => void)[] = [];
	private destroyed = false;
	private initPromise: Promise<void> | null = null;
	private lastSeenAt = 0;
	private typingTimers = new Map<string, ReturnType<typeof setTimeout>>();

	typingNames = $derived.by(() => {
		const names: string[] = [];
		for (const row of Object.values(this.typing)) {
			if (row.actorId !== this.actorId) names.push(row.authorName);
		}
		return names;
	});

	async init(opts: ChatInit) {
		this.famId = opts.famId;
		this.actorId = opts.actorId;
		this.actorType = opts.actorType;
		this.actorName = opts.actorName;
		this.actorColor = opts.actorColor;
		this.deviceToken = opts.deviceToken || '';
		this.memberId = opts.memberId || '';

		if (this.initialized && this.famId === opts.famId) return;
		if (this.initPromise) {
			await this.initPromise;
			if (this.initialized && this.famId === opts.famId) return;
		}

		this.cleanup();
		this.destroyed = false;
		this.lastSeenAt = Date.now();

		this.initPromise = (async () => {
			try {
				// Last week + this week of history (custom createdAt field — the
				// auto `created` field can't be filtered in this PB version).
				const since = new Date(Date.now() - 14 * 86400000).toISOString();
				const msgs = (await pb.collection('messages').getFullList({
					filter: `famId = '${opts.famId}' && createdAt >= '${since}'`,
					sort: 'createdAt'
				})) as ChatMessage[];
				this.messages = msgs;
				this.initialized = true;
			} catch (e) {
				console.error('ChatStore.init failed:', e);
				this.initPromise = null;
				throw e;
			}
			await this.subscribe();
			this.initPromise = null;
		})();

		return this.initPromise!;
	}

	private async subscribe() {
		const msgSub = pb
			.collection('messages')
			.subscribe('*', (data: any) => {
				if (this.destroyed) return;
				this.onMessage(data.action, data.record);
			})
			.then((unsub) => this.unsubs.push(unsub))
			.catch((err: Error) => console.error('[chatStore] messages subscribe failed:', err));

		const typingSub = pb
			.collection('chat_typing')
			.subscribe('*', (data: any) => {
				if (this.destroyed) return;
				this.onTyping(data.action, data.record);
			})
			.then((unsub) => this.unsubs.push(unsub))
			.catch((err: Error) => console.error('[chatStore] typing subscribe failed:', err));

		await Promise.allSettled([msgSub, typingSub]);
	}

	private onMessage(action: string, record: ChatMessage) {
		if (record.famId !== this.famId) return;
		if (action === 'delete') {
			this.messages = this.messages.filter((m) => m.id !== record.id);
			return;
		}
		if (action === 'update') {
			this.messages = this.messages.map((m) => (m.id === record.id ? { ...m, ...record } : m));
			return;
		}
		// create
		if (!this.messages.some((m) => m.id === record.id)) {
			this.messages = [...this.messages, record].sort((a, b) =>
				a.createdAt.localeCompare(b.createdAt)
			);
		}
		// Stop showing their typing indicator once the message lands.
		this.clearTyping(record.authorId);
		if (record.authorId !== this.actorId && !this.open) {
			this.unread++;
		}
	}

	private onTyping(action: string, record: TypingRow) {
		if (record.famId !== this.famId) return;
		if (action === 'delete') {
			this.removeTyping(record.actorId);
			return;
		}
		if (!record.typing) {
			this.removeTyping(record.actorId);
			return;
		}
		this.typing = { ...this.typing, [record.actorId]: record };
		const prev = this.typingTimers.get(record.actorId);
		if (prev) clearTimeout(prev);
		this.typingTimers.set(
			record.actorId,
			setTimeout(() => this.removeTyping(record.actorId), 5000)
		);
	}

	private clearTyping(actorId: string) {
		if (this.typing[actorId]) this.removeTyping(actorId);
	}

	private removeTyping(actorId: string) {
		if (!this.typing[actorId]) return;
		const next = { ...this.typing };
		delete next[actorId];
		this.typing = next;
		const t = this.typingTimers.get(actorId);
		if (t) clearTimeout(t);
		this.typingTimers.delete(actorId);
	}

	// ── Writes via proxy ──

	private async chatFetch(method: string, path: string, body?: unknown) {
		const headers: Record<string, string> = { 'Content-Type': 'application/json' };
		if (this.actorType === 'member' && this.deviceToken) {
			headers['x-device-token'] = this.deviceToken;
			headers['x-device-famid'] = this.famId;
		}
		const res = await fetch(path, {
			method,
			headers,
			body: body ? JSON.stringify(body) : undefined
		});
		const data = await res.json().catch(() => ({}));
		if (!res.ok) throw new Error(data.error || `${method} ${path} failed`);
		return data;
	}

	async send(content: string) {
		const text = content.trim();
		if (!text || !this.famId) return;
		const temp: ChatMessage = {
			id: 'temp-' + Date.now(),
			famId: this.famId,
			authorType: this.actorType,
			authorId: this.actorId,
			authorName: this.actorName,
			authorColor: this.actorColor,
			content: text,
			createdAt: new Date().toISOString()
		};
		this.messages = [...this.messages, temp];
		this.lastSeenAt = Date.now();
		// Signal we stopped typing (message sent).
		this.setTyping(false).catch(() => {});
		try {
			const saved = await this.chatFetch('POST', `/api/chat/${this.famId}/messages`, {
				content: text
			});
			// SSE may have already delivered the real record via onMessage, so
			// drop both the temp and any pre-existing copy of the saved id to
			// avoid duplicate keys in the keyed each block.
			this.messages = this.messages
				.filter((m) => m.id !== temp.id && m.id !== saved.id)
				.concat([{ ...saved, authorName: temp.authorName, authorColor: temp.authorColor }])
				.sort((a, b) => a.createdAt.localeCompare(b.createdAt));
		} catch (e) {
			this.messages = this.messages.filter((m) => m.id !== temp.id);
			console.error('Chat send failed:', e);
			throw e;
		}
	}

	private typingThrottle = 0;
	async setTyping(typing: boolean) {
		if (!this.famId) return;
		const now = Date.now();
		if (typing && now - this.typingThrottle < 1500) return;
		this.typingThrottle = now;
		try {
			await this.chatFetch('POST', `/api/chat/${this.famId}/typing`, { typing });
		} catch (e) {
			console.error('Chat typing failed:', e);
		}
	}

	toggle() {
		this.open = !this.open;
		if (this.open) {
			this.unread = 0;
			this.lastSeenAt = Date.now();
		}
	}

	openChat() {
		this.open = true;
		this.unread = 0;
		this.lastSeenAt = Date.now();
	}

	closeChat() {
		this.open = false;
	}

	cleanup() {
		this.destroyed = true;
		for (const unsub of this.unsubs) unsub();
		this.unsubs = [];
		for (const t of this.typingTimers.values()) clearTimeout(t);
		this.typingTimers.clear();
		this.initialized = false;
	}
}

export const chatStore = new ChatStore();