import {
	DataAdapter,
	KanbanBoard,
	KanbanCard,
	KanbanConfig,
	KanbanLayout,
	NotebookKanbanGroup,
} from "./types";
import resolveScopedFolderIds from "./folderScope";
import resolveScopedFolderMetadata from "./folderTree";
import extractGtdBlock from "./gtdBlock";
import buildKanbanCard from "./buildKanbanCard";

export interface KanbanResult {
	layout: KanbanLayout;
	/** @deprecated Phase 4 moves payload consumers to layout. Single-view alias. */
	board: KanbanBoard;
	warnings: string[];
	scannedFolders: number;
	scannedNotes: number;
	cardCount: number;
}

/**
 * Build a three-column kanban board from admitted to-dos and opted-in notes.
 *
 *  - notes and todos filters apply independently.
 *  - Bucketing: completion wins; else in-progress tag;
 *    else Backlog.
 *  - done-window filters native completed to-dos only.
 *  - Each column sorted per config.
 *
 * The kanban note itself is always excluded.
 */
export default async function collectKanban(
	adapter: DataAdapter,
	kanbanNoteId: string,
	kanbanFolderId: string,
	config: KanbanConfig,
	now: Date = new Date()
): Promise<KanbanResult> {
	const warnings: string[] = [];

	const folders = await adapter.getFolders();
	const folderMetadata = config.groupByNotebook
		? resolveScopedFolderMetadata(folders, kanbanFolderId)
		: [];
	const folderIds = config.groupByNotebook
		? folderMetadata.map((folder) => folder.id)
		: resolveScopedFolderIds(
				folders,
				kanbanFolderId,
				config.scopeDepth,
				config.scopeAll
		  );

	let scannedNotes = 0;
	const backlog: KanbanCard[] = [];
	const inProgress: KanbanCard[] = [];
	const done: KanbanCard[] = [];
	const grouped = new Map<string, { board: KanbanBoard; warnings: string[] }>();
	for (const folder of folderMetadata) {
		grouped.set(folder.id, {
			board: { backlog: [], inProgress: [], done: [] },
			warnings: [],
		});
	}

	const doneCutoff =
		config.doneWindow === Infinity
			? -Infinity
			: now.getTime() - config.doneWindow * 24 * 60 * 60 * 1000;

	// Bodies preserve explicit note opt-in and optional to-do card overrides.
	// When both types are disabled, metadata alone is sufficient for scan totals.
	const includeBody = config.notes !== "none" || config.todos !== "none";

	for (const folderId of folderIds) {
		const target = grouped.get(folderId);
		const targetBoard = target?.board || { backlog, inProgress, done };
		const notes = await adapter.getNotesInFolder(folderId, includeBody);
		for (const note of notes) {
			scannedNotes += 1;
			if (note.id === kanbanNoteId) continue;
			if (!note.is_todo && config.notes === "none") continue;

			const result = extractGtdBlock(note.body);
			if (note.is_todo) {
				if (config.todos === "none") continue;
				if (config.todos === "gtd-only" && !result.found) continue;
			} else if (!result.found) {
				continue;
			}

			if (result.error) {
				const warning = `"${note.title}": gtd block problem — ${result.error}`;
				(target?.warnings || warnings).push(warning);
			}

			const tags = await adapter.getNoteTagTitles(note.id);
			const card = buildKanbanCard(note, result.block, tags, config.doneTag);

			// Bucketing — Done wins.
			if (card.completed) {
				if (!card.isTodo || card.completedTime >= doneCutoff) {
					targetBoard.done.push(card);
				}
				// Only native to-dos can be completed outside the timestamp window.
			} else if (tags.includes(config.inProgressTag)) {
				targetBoard.inProgress.push(card);
			} else {
				targetBoard.backlog.push(card);
			}
		}
	}

	const groups: NotebookKanbanGroup[] = [];
	for (const folder of folderMetadata) {
		const target = grouped.get(folder.id) as {
			board: KanbanBoard;
			warnings: string[];
		};
		sortBoard(target.board, config);
		const cardCount = countBoard(target.board);
		if (cardCount > 0) {
			groups.push({
				folderId: folder.id,
				notebookPath: folder.notebookPath,
				board: target.board,
				cardCount,
				warnings: target.warnings,
			});
		}
	}
	if (!config.groupByNotebook) sortBoard({ backlog, inProgress, done }, config);
	const board = { backlog, inProgress, done };
	const layout: KanbanLayout = config.groupByNotebook
		? { kind: "notebooks", groups }
		: { kind: "single", board };
	const cardCount = config.groupByNotebook
		? groups.reduce((sum, group) => sum + group.cardCount, 0)
		: countBoard(board);

	return {
		layout,
		board,
		warnings,
		scannedFolders: folderIds.length,
		scannedNotes,
		cardCount,
	};
}

function sortBoard(board: KanbanBoard, config: KanbanConfig): void {
	sortColumn(board.backlog, config);
	sortColumn(board.inProgress, config);
	sortColumn(board.done, config);
}

function countBoard(board: KanbanBoard): number {
	return board.backlog.length + board.inProgress.length + board.done.length;
}

function sortColumn(cards: KanbanCard[], config: KanbanConfig): void {
	const direction = config.sort === "desc" ? -1 : 1;

	cards.sort((a, b) => {
		let comparison: number;

		if (config.sortType === "due-date") {
			// Dateless cards always sort after dated ones, regardless of
			// direction.
			const aHas = a.date !== null;
			const bHas = b.date !== null;
			if (aHas && !bHas) return -1;
			if (!aHas && bHas) return 1;
			if (!aHas && !bHas) {
				comparison = 0;
			} else {
				comparison = (a.date as string).localeCompare(b.date as string);
			}
		} else if (config.sortType === "modified-date") {
			comparison = a.updatedTime - b.updatedTime;
		} else {
			comparison = a.title.localeCompare(b.title, undefined, {
				sensitivity: "base",
			});
		}

		return comparison * direction;
	});
}