import type { MessageData, ReactionSummary } from '$lib/types/message';
import type { ChatConnection, ChatUser, MentionRef } from './types';
import { DbConnection, type EventContext } from './module_bindings';

/**
 * SpacetimeDB-only chat-adapter.
 * All data (historikk + sanntid) kommer fra SpacetimeDB.
 * Worker håndterer warmup (PG → ST) og sync (ST → PG).
 * Frontend snakker KUN med SpacetimeDB.
 */
export function createSpacetimeChat(
	channelId: string,
	spacetimeUrl: string,
	moduleName: string,
	user: ChatUser,
	workspaceId: string
): ChatConnection {
	let messages = $state<MessageData[]>([]);
	let error = $state('');
	let connected = $state(false);
	let conn: InstanceType<typeof DbConnection> | null = null;
	let destroyed = false;
	// Lokal reaksjonsstate (SpacetimeDB har message_reaction-tabellen)
	let reactionMap = $state<Map<string, ReactionSummary[]>>(new Map());

	function spacetimeRowToMessage(row: any): MessageData {
		let createdAt: string;
		try {
			const micros = row.createdAt?.microsSinceEpoch;
			const ms = typeof micros === 'bigint' ? Number(micros / 1000n) : Number(micros) / 1000;
			createdAt = new Date(ms).toISOString();
		} catch {
			createdAt = new Date().toISOString();
		}

		// Parse metadata fra JSON-streng
		let metadata: MessageData['metadata'] = null;
		if (row.metadata) {
			try {
				metadata = JSON.parse(row.metadata);
			} catch { /* ugyldig JSON — ignorer */ }
		}

		return {
			id: row.id,
			channel_id: channelId,
			reply_to: row.replyTo || null,
			author_id: row.authorId || null,
			author_name: row.authorName || null,
			message_type: row.messageType ?? 'chat',
			title: null,
			body: row.body,
			pinned: false,
			visibility: 'workspace',
			created_at: createdAt,
			updated_at: createdAt,
			reactions: reactionMap.get(row.id) ?? [],
			kanban_view: null,
			calendar_view: null,
			metadata,
			edited_at: row.editedAt || null
		};
	}

	function rebuildReactions() {
		// Bygg reaksjonsaggregat fra message_reaction-tabellen
		if (!conn) return;
		const newMap = new Map<string, ReactionSummary[]>();

		for (const r of conn.db.message_reaction.iter()) {
			const msgId = r.messageId;
			if (!newMap.has(msgId)) newMap.set(msgId, []);
			const summaries = newMap.get(msgId)!;
			const existing = summaries.find(s => s.reaction === r.reaction);
			if (existing) {
				existing.count++;
				if (r.userId === user.id) existing.user_reacted = true;
			} else {
				summaries.push({
					reaction: r.reaction,
					count: 1,
					user_reacted: r.userId === user.id
				});
			}
		}

		reactionMap = newMap;
	}

	function rebuildMessages() {
		if (!conn) return;
		const rows: any[] = [];
		for (const row of conn.db.chat_message.iter()) {
			if (row.channelId === channelId) {
				rows.push(row);
			}
		}
		// Sorter kronologisk
		rows.sort((a, b) => {
			const aMs = extractMs(a.createdAt);
			const bMs = extractMs(b.createdAt);
			return aMs - bMs;
		});
		// Bevar felter som ikke finnes i SpacetimeDB (reply_count, parent_body, etc.)
		const existing = new Map(messages.map(m => [m.id, m]));
		messages = rows.map(r => {
			const msg = spacetimeRowToMessage(r);
			const prev = existing.get(msg.id);
			if (prev) {
				msg.reply_count = prev.reply_count;
				msg.parent_body = prev.parent_body;
				msg.parent_author_name = prev.parent_author_name;
			}
			return msg;
		});
	}

	function extractMs(ts: any): number {
		try {
			const micros = ts?.microsSinceEpoch;
			return typeof micros === 'bigint' ? Number(micros / 1000n) : Number(micros) / 1000;
		} catch {
			return 0;
		}
	}

	function connectRealtime() {
		try {
			conn = DbConnection.builder()
				.withUri(spacetimeUrl)
				.withDatabaseName(moduleName)
				.onConnect((connection) => {
					if (destroyed) return;
					connected = true;
					error = '';

					try {
						sessionStorage.setItem('spacetime_token', '');
					} catch { /* SSR-safe */ }

					// Abonner på meldinger + reaksjoner for denne kanalen
					connection.subscriptionBuilder()
						.onApplied(() => {
							// Initialload — bygg state fra subscription
							rebuildReactions();
							rebuildMessages();
						})
						.onError(() => {
							console.error('[spacetime] subscription error');
						})
						.subscribe([
							`SELECT * FROM chat_message WHERE channel_id = '${channelId}'`,
							`SELECT * FROM message_reaction`,
							`SELECT * FROM message_revision`
						]);
				})
				.onDisconnect(() => {
					connected = false;
				})
				.onConnectError((_ctx, err) => {
					console.warn('[spacetime] connection error:', err);
					error = 'Tilkobling til sanntidstjeneste feilet';
				})
				.withToken(getStoredToken() ?? '')
				.build();

			// Nye meldinger i sanntid
			conn.db.chat_message.onInsert((_ctx: EventContext, row) => {
				if (destroyed || row.channelId !== channelId) return;
				if (messages.some(m => m.id === row.id)) return;
				const msg = spacetimeRowToMessage(row);
				messages = [...messages, msg];
			});

			// Meldinger oppdatert (edit)
			conn.db.chat_message.onUpdate((_ctx: EventContext, _oldRow, newRow) => {
				if (destroyed || newRow.channelId !== channelId) return;
				let metadata: MessageData['metadata'] = null;
				if (newRow.metadata) {
					try { metadata = JSON.parse(newRow.metadata); } catch { /* ignorer */ }
				}
				messages = messages.map(m =>
					m.id === newRow.id ? { ...m, body: newRow.body, edited_at: newRow.editedAt || m.edited_at, metadata } : m
				);
			});

			// Meldinger slettet
			conn.db.chat_message.onDelete((_ctx: EventContext, row) => {
				if (destroyed || row.channelId !== channelId) return;
				messages = messages.filter(m => m.id !== row.id);
			});

			// Reaksjoner — rebuild ved endring
			conn.db.message_reaction.onInsert((_ctx: EventContext, _row) => {
				if (destroyed) return;
				rebuildReactions();
				// Oppdater reactions i messages
				messages = messages.map(m => ({
					...m,
					reactions: reactionMap.get(m.id) ?? []
				}));
			});

			conn.db.message_reaction.onDelete((_ctx: EventContext, _row) => {
				if (destroyed) return;
				rebuildReactions();
				messages = messages.map(m => ({
					...m,
					reactions: reactionMap.get(m.id) ?? []
				}));
			});
		} catch (e) {
			console.warn('[spacetime] setup feilet:', e);
			error = 'Kunne ikke koble til sanntidstjeneste';
		}
	}

	async function send(body: string, _mentions?: MentionRef[], replyTo?: string) {
		if (!conn || !connected) {
			error = 'Ikke tilkoblet';
			return;
		}
		try {
			const id = crypto.randomUUID();
			conn.reducers.sendMessage({
				id,
				channelId,
				workspaceId,
				authorId: user.id,
				authorName: user.name,
				body,
				replyTo: replyTo ?? ''
			});
		} catch {
			error = 'Kunne ikke sende melding';
		}
	}

	async function edit(messageId: string, newBody: string) {
		if (!conn || !connected) return;
		try {
			conn.reducers.editMessage({
				id: messageId,
				workspaceId,
				newBody
			});
		} catch {
			error = 'Kunne ikke redigere melding';
		}
	}

	async function del(messageId: string) {
		if (!conn || !connected) return;
		try {
			conn.reducers.deleteMessage({
				id: messageId,
				workspaceId
			});
		} catch {
			error = 'Kunne ikke slette melding';
		}
	}

	async function react(messageId: string, reaction: string) {
		if (!conn || !connected) return;
		try {
			// Sjekk om bruker allerede har reagert med denne
			const existing = reactionMap.get(messageId)?.find(
				r => r.reaction === reaction && r.user_reacted
			);
			if (existing) {
				conn.reducers.removeReaction({
					messageId,
					workspaceId,
					userId: user.id,
					reaction
				});
			} else {
				conn.reducers.addReaction({
					messageId,
					workspaceId,
					userId: user.id,
					userName: user.name,
					reaction
				});
			}
		} catch {
			error = 'Kunne ikke legge til reaksjon';
		}
	}

	function getRevisions(messageId: string): { id: string; body: string; edited_at: string }[] {
		if (!conn) return [];
		const revs: { id: string; body: string; edited_at: string }[] = [];
		for (const r of conn.db.message_revision.iter()) {
			if (r.messageId === messageId) {
				revs.push({
					id: String(r.id),
					body: r.body,
					edited_at: r.editedAt
				});
			}
		}
		// Sorter nyeste først
		revs.sort((a, b) => b.edited_at.localeCompare(a.edited_at));
		return revs;
	}

	function destroy() {
		destroyed = true;
		if (conn) {
			conn.disconnect();
			conn = null;
		}
	}

	function getStoredToken(): string | undefined {
		try {
			return sessionStorage.getItem('spacetime_token') ?? undefined;
		} catch {
			return undefined;
		}
	}

	// Start tilkobling
	connectRealtime();

	return {
		get messages() { return messages; },
		get error() { return error; },
		get connected() { return connected; },
		get readonly() { return false; },
		send,
		edit,
		delete: del,
		react,
		refresh: async () => { rebuildMessages(); },
		destroy,
		getRevisions
	};
}