import { CalendarConfig, InclusionMode } from "./types";

const VIEW_ALIASES: Record<string, CalendarConfig["view"]> = {
	day: "day",
	d: "day",
	week: "week",
	w: "week",
	month: "month",
	m: "month",
};

const INCLUSION_MODES: InclusionMode[] = ["gtd-only", "all", "none"];

/**
 * Normalise a parsed gtd-calendar YAML object into a CalendarConfig,
 * applying SPEC.md defaults. Unknown keys and invalid values produce
 * warnings rather than failures.
 */
export default function parseCalendarConfig(raw: any): CalendarConfig {
	const warnings: string[] = [];
	const input = raw && typeof raw === "object" ? raw : {};

	const knownKeys = [
		"view",
		"title",
		"scope",
		"notes",
		"todos",
		"sort",
		"sort-type",
	];
	for (const key of Object.keys(input)) {
		if (!knownKeys.includes(key)) warnings.push(`Unknown option "${key}"`);
	}

	// view
	let view: CalendarConfig["view"] = "day";
	if (input.view !== undefined) {
		const candidate = String(input.view).toLowerCase();
		if (VIEW_ALIASES[candidate]) {
			view = VIEW_ALIASES[candidate];
		} else {
			warnings.push(`Invalid view "${input.view}" (using "day")`);
		}
	}

	// title
	const title =
		input.title !== undefined && input.title !== null
			? String(input.title)
			: null;

	// scope
	let scopeDepth = 0;
	if (input.scope !== undefined) {
		const value = input.scope;
		if (value === "this-folder") {
			scopeDepth = 0;
		} else if (value === "children") {
			scopeDepth = Infinity;
		} else if (Number.isInteger(Number(value)) && Number(value) >= 0) {
			scopeDepth = Number(value);
		} else {
			warnings.push(`Invalid scope "${value}" (using "this-folder")`);
		}
	}

	// notes / todos
	const notes = parseInclusion(input.notes, "notes", warnings);
	const todos = parseInclusion(input.todos, "todos", warnings);

	// sort
	let sort: CalendarConfig["sort"] = "asc";
	if (input.sort !== undefined) {
		const candidate = String(input.sort).toLowerCase();
		if (candidate === "asc" || candidate === "desc") {
			sort = candidate;
		} else {
			warnings.push(`Invalid sort "${input.sort}" (using "asc")`);
		}
	}

	// sort-type
	let sortType: CalendarConfig["sortType"] = "title";
	if (input["sort-type"] !== undefined) {
		const candidate = String(input["sort-type"]).toLowerCase();
		if (candidate === "title" || candidate === "modified_date") {
			sortType = candidate as CalendarConfig["sortType"];
		} else {
			warnings.push(
				`Invalid sort-type "${input["sort-type"]}" (using "title")`
			);
		}
	}

	return { view, title, scopeDepth, notes, todos, sort, sortType, warnings };
}

function parseInclusion(
	value: any,
	optionName: string,
	warnings: string[]
): InclusionMode {
	if (value === undefined) return "gtd-only";
	const candidate = String(value).toLowerCase() as InclusionMode;
	if (INCLUSION_MODES.includes(candidate)) return candidate;
	warnings.push(`Invalid ${optionName} "${value}" (using "gtd-only")`);
	return "gtd-only";
}