const YAML = require("yaml");

import extractGtdBlock from "./gtdBlock";
import resolveScopedFolderIds from "./folderScope";
import { moveKanbanItem } from "./kanbanMutation";
import { isKanbanDestination } from "./moveProtocol";
import parseKanbanConfig from "./parseKanbanConfig";
import resolveNotebook from "./resolveNotebook";
import {
	DataAdapter,
	MoveCardResult,
	MoveKanbanCardIntent,
	MutationAdapter,
	RawFolder,
	RawNote,
} from "./types";

export interface KanbanMoveHost {
	id: string;
	parentId: string;
}

function stale(viewInstanceId: string, message: string): MoveCardResult {
	return { status: "stale", viewInstanceId, message };
}

function error(viewInstanceId: string, message: string): MoveCardResult {
	return { status: "error", viewInstanceId, message };
}

function validId(value: unknown): value is string {
	return typeof value === "string" && value.trim().length > 0;
}

class StaleMoveError extends Error {}

function validateFreshEligibility(
	note: RawNote,
	host: KanbanMoveHost,
	folderIds: Set<string>,
	config: ReturnType<typeof parseKanbanConfig>
): void {
	if (note.id === host.id) throw new StaleMoveError("The dashboard note cannot be moved.");
	if (!folderIds.has(note.parent_id)) throw new StaleMoveError("The card is no longer in scope.");
	if (!note.is_todo && config.notes === "none") {
		throw new StaleMoveError("The card is no longer admitted by notes.");
	}
	const block = extractGtdBlock(note.body);
	if (note.is_todo) {
		if (config.todos === "none") throw new StaleMoveError("The card is no longer admitted by todos.");
		if (config.todos === "gtd-only" && !block.found) {
			throw new StaleMoveError("The to-do no longer contains a gtd block.");
		}
	} else if (!block.found) {
		throw new StaleMoveError("The note no longer contains a gtd block.");
	}
}

/** Validate untrusted webview intent against fresh host, scope, and item state. */
export async function validateAndMoveKanbanCard(
	intent: unknown,
	host: KanbanMoveHost | null,
	readAdapter: DataAdapter,
	mutationAdapter: MutationAdapter,
	now: () => number = Date.now,
	logDiagnostic: (error: unknown) => void = () => undefined
): Promise<MoveCardResult> {
	const candidate = intent as Partial<MoveKanbanCardIntent> | null;
	const viewInstanceId = validId(candidate?.viewInstanceId)
		? candidate.viewInstanceId
		: "unknown";
	const allowedKeys = new Set([
		"type", "view", "hostNoteId", "cardId", "destination", "rawConfig", "viewInstanceId",
	]);
	if (
		!candidate ||
		Array.isArray(candidate) ||
		Object.keys(candidate).some((key) => !allowedKeys.has(key)) ||
		candidate.type !== "moveKanbanCard" ||
		candidate.view !== "kanban" ||
		!validId(candidate.hostNoteId) ||
		!validId(candidate.cardId) ||
		!validId(candidate.viewInstanceId) ||
		typeof candidate.rawConfig !== "string" ||
		!isKanbanDestination(candidate.destination)
	) {
		return error(viewInstanceId, "Invalid kanban move request.");
	}
	if (!host || candidate.hostNoteId !== host.id) {
		return stale(viewInstanceId, "The rendered dashboard is no longer current.");
	}

	let parsed: unknown;
	try {
		parsed = YAML.parse(candidate.rawConfig || "") || {};
	} catch (_parseError) {
		return stale(viewInstanceId, "The kanban configuration is no longer valid.");
	}
	const config = parseKanbanConfig(parsed);
	if (!config.editable) {
		return error(viewInstanceId, "This kanban is read-only.");
	}

	try {
		const folders = await readAdapter.getFolders();
		let scanFolderId = host.parentId;
		if (!config.scopeAll && config.notebook) {
			scanFolderId = resolveNotebook(folders, config.notebook, host.parentId).folderId;
		}
		const folderIds = new Set(
			resolveScopedFolderIds(folders, scanFolderId, config.scopeDepth, config.scopeAll)
		);
		const outcome = await moveKanbanItem(
			mutationAdapter,
			candidate.cardId,
			candidate.destination,
			config,
			now,
			(note) => validateFreshEligibility(note, host, folderIds, config)
		);
		return { status: "success", viewInstanceId, changed: outcome.changed };
	} catch (moveError) {
		if (moveError instanceof StaleMoveError) {
			return stale(viewInstanceId, moveError.message);
		}
		if (moveError instanceof Error && moveError.message === "The card no longer exists.") {
			return stale(viewInstanceId, moveError.message);
		}
		logDiagnostic(moveError);
		return error(viewInstanceId, "Could not apply the move. Refresh and try again.");
	}
}