import {
	CalendarConfig,
	DataAdapter,
	GtdEvent,
	RawNote,
	RECURRING_TAG,
} from "./types";
import resolveScopedFolderIds from "./folderScope";
import extractGtdBlock from "./gtdBlock";
import { resolveEventDate } from "./resolveDate";

export interface CollectResult {
	events: GtdEvent[];
	warnings: string[];
	scannedFolders: number;
	scannedNotes: number;
}

/**
 * Collect calendar events per SPEC.md:
 *  - resolve folder scope from the calendar note's folder
 *  - fetch notes/todos in scope
 *  - apply the inclusion matrix (§3.2)
 *  - resolve dates (§3.1)
 *  - sort within the flat list (grouping happens at render time)
 *
 * The calendar note itself is always excluded.
 */
export default async function collectEvents(
	adapter: DataAdapter,
	calendarNoteId: string,
	calendarFolderId: string,
	config: CalendarConfig
): Promise<CollectResult> {
	const warnings: string[] = [];

	const folders = await adapter.getFolders();
	const folderIds = resolveScopedFolderIds(
		folders,
		calendarFolderId,
		config.scopeDepth
	);

	let scannedNotes = 0;
	const events: GtdEvent[] = [];

	for (const folderId of folderIds) {
		const notes = await adapter.getNotesInFolder(folderId);
		for (const note of notes) {
			scannedNotes += 1;
			if (note.id === calendarNoteId) continue;

			const event = await noteToEvent(adapter, note, config, warnings);
			if (event) events.push(event);
		}
	}

	sortEvents(events, config);

	return {
		events,
		warnings,
		scannedFolders: folderIds.length,
		scannedNotes,
	};
}

async function noteToEvent(
	adapter: DataAdapter,
	note: RawNote,
	config: CalendarConfig,
	warnings: string[]
): Promise<GtdEvent | null> {
	const mode = note.is_todo ? config.todos : config.notes;
	if (mode === "none") return null;

	const result = extractGtdBlock(note.body);
	if (mode === "gtd-only" && !result.found) return null;

	if (result.error) {
		warnings.push(`"${note.title}": gtd block problem — ${result.error}`);
	}

	const block = result.block;
	const date = resolveEventDate(note, block);

	if (block && block.date && !date) {
		warnings.push(`"${note.title}": unparseable date "${block.date}"`);
	}

	// Only to-dos can recur; skip the tag lookup for plain notes.
	let isRecurring = false;
	if (note.is_todo) {
		const tags = await adapter.getNoteTagTitles(note.id);
		isRecurring = tags.includes(RECURRING_TAG);
	}

	return {
		id: note.id,
		title: block && block.title ? block.title : note.title,
		date,
		isTodo: Boolean(note.is_todo),
		completed: Boolean(note.is_todo && note.todo_completed > 0),
		bgColour: block ? block.bgColour : null,
		fgColour: block ? block.fgColour : null,
		icon: block ? block.icon : null,
		text: block ? block.text : null,
		updatedTime: note.updated_time,
		isRecurring,
	};
}

function sortEvents(events: GtdEvent[], config: CalendarConfig): void {
	const direction = config.sort === "desc" ? -1 : 1;

	events.sort((a, b) => {
		let comparison: number;
		if (config.sortType === "modified_date") {
			comparison = a.updatedTime - b.updatedTime;
		} else {
			comparison = a.title.localeCompare(b.title, undefined, {
				sensitivity: "base",
			});
		}
		return comparison * direction;
	});
}