import type { SupabaseClient } from '@supabase/supabase-js';
import type { Database, KanbanBoard, KanbanColumn, KanbanCard } from '$lib/supabase/types';
import { createLogger } from '$lib/utils/logger';

const log = createLogger('api.kanban');

export interface ColumnWithCards extends KanbanColumn {
	cards: KanbanCard[];
}

export interface BoardWithColumns extends KanbanBoard {
	columns: ColumnWithCards[];
}

export async function fetchBoards(
	supabase: SupabaseClient<Database>,
	orgId: string
): Promise<KanbanBoard[]> {
	const { data, error } = await supabase
		.from('kanban_boards')
		.select('*')
		.eq('org_id', orgId)
		.order('created_at');

	if (error) {
		log.error('fetchBoards failed', { error, data: { orgId } });
		throw error;
	}
	log.debug('fetchBoards ok', { data: { count: data?.length ?? 0 } });
	return data ?? [];
}

export async function fetchBoardWithColumns(
	supabase: SupabaseClient<Database>,
	boardId: string
): Promise<BoardWithColumns | null> {
	// Fetch board and columns in parallel
	const [boardResult, columnsResult] = await Promise.all([
		supabase.from('kanban_boards').select('*').eq('id', boardId).single(),
		supabase.from('kanban_columns').select('*').eq('board_id', boardId).order('position'),
	]);

	if (boardResult.error) {
		log.error('fetchBoardWithColumns failed (board)', { error: boardResult.error, data: { boardId } });
		throw boardResult.error;
	}
	if (!boardResult.data) return null;

	if (columnsResult.error) {
		log.error('fetchBoardWithColumns failed (columns)', { error: columnsResult.error, data: { boardId } });
		throw columnsResult.error;
	}

	const board = boardResult.data;
	const columns = columnsResult.data ?? [];
	const columnIds = columns.map((c) => c.id);

	if (columnIds.length === 0) {
		return { ...board, columns: columns.map((col) => ({ ...col, cards: [] })) };
	}

	const { data: cards, error: cardError } = await supabase
		.from('kanban_cards')
		.select('*')
		.in('column_id', columnIds)
		.order('position');

	if (cardError) {
		log.error('fetchBoardWithColumns failed (cards)', { error: cardError, data: { boardId } });
		throw cardError;
	}

	const cardIds = (cards ?? []).map((c) => c.id);
	const cardTagsMap = new Map<string, { id: string; name: string; color: string | null }[]>();
	const checklistMap = new Map<string, { total: number; done: number }>();
	const assigneeMap = new Map<string, { name: string | null; avatar: string | null }>();

	if (cardIds.length > 0) {
		const assigneeIds = [...new Set((cards ?? []).map((c) => c.assignee_id).filter(Boolean))] as string[];

		// Fetch tags, checklists, and assignee profiles in parallel
		const [cardTagsResult, checklistResult, profilesResult] = await Promise.all([
			supabase.from('card_tags').select('card_id, tags:tag_id (id, name, color)').in('card_id', cardIds),
			supabase.from('kanban_checklist_items').select('card_id, completed').in('card_id', cardIds),
			assigneeIds.length > 0
				? supabase.from('profiles').select('id, full_name, avatar_url').in('id', assigneeIds)
				: Promise.resolve({ data: null }),
		]);

		(cardTagsResult.data ?? []).forEach((ct: Record<string, unknown>) => {
			const rawTags = ct.tags;
			const tag = Array.isArray(rawTags) ? rawTags[0] : rawTags;
			if (!tag) return;
			const cardId = ct.card_id as string;
			if (!cardTagsMap.has(cardId)) {
				cardTagsMap.set(cardId, []);
			}
			cardTagsMap.get(cardId)!.push(tag as { id: string; name: string; color: string | null });
		});

		(checklistResult.data ?? []).forEach((item: Record<string, unknown>) => {
			const cardId = item.card_id as string;
			if (!checklistMap.has(cardId)) {
				checklistMap.set(cardId, { total: 0, done: 0 });
			}
			const entry = checklistMap.get(cardId)!;
			entry.total++;
			if (item.completed) entry.done++;
		});

		(profilesResult.data ?? []).forEach((p: Record<string, unknown>) => {
			assigneeMap.set(p.id as string, { name: p.full_name as string | null, avatar: p.avatar_url as string | null });
		});
	}

	const cardsByColumn = new Map<string, (KanbanCard & { tags?: { id: string; name: string; color: string | null }[]; checklist_total?: number; checklist_done?: number; assignee_name?: string | null; assignee_avatar?: string | null })[]>();
	(cards ?? []).forEach((card) => {
		const colId = card.column_id;
		if (!colId) return;
		if (!cardsByColumn.has(colId)) {
			cardsByColumn.set(colId, []);
		}
		const cl = checklistMap.get(card.id);
		const assignee = card.assignee_id ? assigneeMap.get(card.assignee_id) : null;
		cardsByColumn.get(colId)!.push({
			...card,
			tags: cardTagsMap.get(card.id) ?? [],
			checklist_total: cl?.total ?? 0,
			checklist_done: cl?.done ?? 0,
			assignee_name: assignee?.name ?? null,
			assignee_avatar: assignee?.avatar ?? null,
		});
	});

	return {
		...board,
		columns: columns.map((col) => ({
			...col,
			cards: cardsByColumn.get(col.id) ?? []
		}))
	};
}

export async function createBoard(
	supabase: SupabaseClient<Database>,
	orgId: string,
	name: string
): Promise<KanbanBoard> {
	log.info('createBoard', { data: { orgId, name } });
	const { data, error } = await supabase
		.from('kanban_boards')
		.insert({ org_id: orgId, name })
		.select()
		.single();

	if (error) {
		log.error('createBoard failed', { error, data: { orgId, name } });
		throw error;
	}

	// Create default columns
	const defaultColumns = ['To Do', 'In Progress', 'Done'];
	await supabase.from('kanban_columns').insert(
		defaultColumns.map((name, index) => ({
			board_id: data.id,
			name,
			position: index
		}))
	);

	return data;
}

export async function updateBoard(
	supabase: SupabaseClient<Database>,
	id: string,
	name: string
): Promise<void> {
	const { error } = await supabase.from('kanban_boards').update({ name }).eq('id', id);
	if (error) {
		log.error('updateBoard failed', { error, data: { id, name } });
		throw error;
	}
}

export async function deleteBoard(
	supabase: SupabaseClient<Database>,
	id: string
): Promise<void> {
	const { error } = await supabase.from('kanban_boards').delete().eq('id', id);
	if (error) {
		log.error('deleteBoard failed', { error, data: { id } });
		throw error;
	}
}

export async function createColumn(
	supabase: SupabaseClient<Database>,
	boardId: string,
	name: string,
	position: number
): Promise<KanbanColumn> {
	const { data, error } = await supabase
		.from('kanban_columns')
		.insert({ board_id: boardId, name, position })
		.select()
		.single();

	if (error) {
		log.error('createColumn failed', { error, data: { boardId, name, position } });
		throw error;
	}
	return data;
}

export async function updateColumn(
	supabase: SupabaseClient<Database>,
	id: string,
	updates: Partial<Pick<KanbanColumn, 'name' | 'position' | 'color'>>
): Promise<void> {
	const { error } = await supabase.from('kanban_columns').update(updates).eq('id', id);
	if (error) {
		log.error('updateColumn failed', { error, data: { id, updates } });
		throw error;
	}
}

export async function deleteColumn(
	supabase: SupabaseClient<Database>,
	id: string
): Promise<void> {
	const { error } = await supabase.from('kanban_columns').delete().eq('id', id);
	if (error) {
		log.error('deleteColumn failed', { error, data: { id } });
		throw error;
	}
}

export async function createCard(
	supabase: SupabaseClient<Database>,
	columnId: string,
	title: string,
	position: number,
	userId: string
): Promise<KanbanCard> {
	const { data, error } = await supabase
		.from('kanban_cards')
		.insert({
			column_id: columnId,
			title,
			position,
			created_by: userId
		})
		.select()
		.single();

	if (error) {
		log.error('createCard failed', { error, data: { columnId, title, position } });
		throw error;
	}
	return data;
}

export async function updateCard(
	supabase: SupabaseClient<Database>,
	id: string,
	updates: Partial<Pick<KanbanCard, 'title' | 'description' | 'column_id' | 'position' | 'due_date' | 'color'>>
): Promise<void> {
	const { error } = await supabase.from('kanban_cards').update(updates).eq('id', id);
	if (error) {
		log.error('updateCard failed', { error, data: { id, updates } });
		throw error;
	}
}

export async function deleteCard(
	supabase: SupabaseClient<Database>,
	id: string
): Promise<void> {
	const { error } = await supabase.from('kanban_cards').delete().eq('id', id);
	if (error) {
		log.error('deleteCard failed', { error, data: { id } });
		throw error;
	}
}

export async function moveCard(
	supabase: SupabaseClient<Database>,
	cardId: string,
	newColumnId: string,
	newPosition: number
): Promise<void> {
	// Fetch all cards in the target column (ordered by position)
	const { data: targetCards, error: fetchErr } = await supabase
		.from('kanban_cards')
		.select('id, position')
		.eq('column_id', newColumnId)
		.order('position');

	if (fetchErr) {
		log.error('moveCard: failed to fetch target column cards', { error: fetchErr });
		throw fetchErr;
	}

	// Remove the moved card from the list if it's already in this column
	const otherCards = (targetCards ?? []).filter((c) => c.id !== cardId);

	// Insert at the new position and reassign sequential positions
	const reordered = [
		...otherCards.slice(0, newPosition),
		{ id: cardId },
		...otherCards.slice(newPosition),
	];

	// Build a map of old positions to detect what actually changed
	const oldPositionMap = new Map((targetCards ?? []).map((c) => [c.id, c.position]));

	// Only update cards whose position or column actually changed
	const updates = reordered
		.map((c, i) => {
			if (c.id === cardId) {
				// The moved card always needs updating (column + position)
				return supabase
					.from('kanban_cards')
					.update({ column_id: newColumnId, position: i })
					.eq('id', c.id);
			}
			// Skip siblings whose position hasn't changed
			if (oldPositionMap.get(c.id) === i) return null;
			return supabase
				.from('kanban_cards')
				.update({ position: i })
				.eq('id', c.id);
		})
		.filter(Boolean);

	if (updates.length === 0) return;

	const results = await Promise.all(updates);
	const failed = results.find((r) => r && r.error);
	if (failed?.error) {
		log.error('moveCard failed', { error: failed.error, data: { cardId, newColumnId, newPosition } });
		throw failed.error;
	}
}

export interface RealtimeChangePayload<T = Record<string, unknown>> {
	event: 'INSERT' | 'UPDATE' | 'DELETE';
	new: T;
	old: Partial<T>;
}

export function subscribeToBoard(
	supabase: SupabaseClient<Database>,
	boardId: string,
	columnIds: string[],
	onColumnChange: (payload: RealtimeChangePayload<KanbanColumn>) => void,
	onCardChange: (payload: RealtimeChangePayload<KanbanCard>) => void
) {
	const channel = supabase.channel(`kanban:${boardId}`);
	const columnIdSet = new Set(columnIds);

	channel
		.on('postgres_changes', { event: '*', schema: 'public', table: 'kanban_columns', filter: `board_id=eq.${boardId}` },
			(payload) => onColumnChange({
				event: payload.eventType as 'INSERT' | 'UPDATE' | 'DELETE',
				new: payload.new as KanbanColumn,
				old: payload.old as Partial<KanbanColumn>,
			})
		)
		.on('postgres_changes', { event: '*', schema: 'public', table: 'kanban_cards' },
			(payload) => {
				// Client-side filter: only process cards belonging to this board's columns
				const card = (payload.new ?? payload.old) as Partial<KanbanCard>;
				const colId = card.column_id ?? (payload.old as Partial<KanbanCard>)?.column_id;
				if (colId && !columnIdSet.has(colId)) return;

				onCardChange({
					event: payload.eventType as 'INSERT' | 'UPDATE' | 'DELETE',
					new: payload.new as KanbanCard,
					old: payload.old as Partial<KanbanCard>,
				});
			}
		)
		.subscribe();

	return channel;
}