import {
	DEFAULT_EDITOR_LAYOUT_SETTINGS,
	DEFAULT_EXPORT_SETTINGS,
} from "@/components/video-editor/editorDefaults";
import type { ExportFormat, ExportQuality } from "@/lib/exporter";
import type { AspectRatio } from "@/utils/aspectRatioUtils";

const PREFS_KEY = "openscreen_user_preferences";

const VALID_ASPECT_RATIOS: readonly string[] = [
	"16:9",
	"9:16",
	"1:1",
	"4:3",
	"4:5",
	"16:10",
	"10:16",
	"native",
];

export interface UserPreferences {
	/** Default padding % */
	padding: number;
	/** Default aspect ratio */
	aspectRatio: AspectRatio;
	/** Default export quality */
	exportQuality: ExportQuality;
	/** Default export format */
	exportFormat: ExportFormat;
	/** Folder used for the most recent successful export, if any */
	exportFolder: string | null;
}

export const DEFAULT_PREFS: UserPreferences = {
	padding: DEFAULT_EDITOR_LAYOUT_SETTINGS.padding,
	aspectRatio: DEFAULT_EDITOR_LAYOUT_SETTINGS.aspectRatio,
	exportQuality: DEFAULT_EXPORT_SETTINGS.quality,
	exportFormat: DEFAULT_EXPORT_SETTINGS.format,
	exportFolder: null,
};

function safeJsonParse(text: string | null): Record<string, unknown> | null {
	if (!text) return null;
	try {
		return JSON.parse(text);
	} catch {
		return null;
	}
}

/**
 * Load persisted user preferences from localStorage.
 * Returns defaults for any missing or invalid fields.
 */
export function loadUserPreferences(): UserPreferences {
	let raw: Record<string, unknown> | null = null;
	try {
		raw = safeJsonParse(localStorage.getItem(PREFS_KEY));
	} catch {
		return { ...DEFAULT_PREFS };
	}
	if (!raw || typeof raw !== "object") return { ...DEFAULT_PREFS };

	return {
		padding:
			typeof raw.padding === "number" &&
			Number.isFinite(raw.padding) &&
			raw.padding >= 0 &&
			raw.padding <= 100
				? raw.padding
				: DEFAULT_PREFS.padding,
		aspectRatio:
			typeof raw.aspectRatio === "string" && VALID_ASPECT_RATIOS.includes(raw.aspectRatio)
				? (raw.aspectRatio as AspectRatio)
				: DEFAULT_PREFS.aspectRatio,
		exportQuality:
			raw.exportQuality === "medium" ||
			raw.exportQuality === "good" ||
			raw.exportQuality === "source"
				? (raw.exportQuality as ExportQuality)
				: DEFAULT_PREFS.exportQuality,
		exportFormat:
			raw.exportFormat === "gif" || raw.exportFormat === "mp4"
				? (raw.exportFormat as ExportFormat)
				: DEFAULT_PREFS.exportFormat,
		exportFolder:
			typeof raw.exportFolder === "string" && raw.exportFolder.length > 0
				? raw.exportFolder
				: DEFAULT_PREFS.exportFolder,
	};
}

/**
 * Extracts the parent directory from a saved file path. Handles both POSIX
 * and Windows separators since the path comes from the OS save dialog.
 *
 * Root directories are preserved with their trailing separator so that the
 * value is still a valid directory path:
 *   "/video.mp4"      -> "/"
 *   "C:\\video.mp4"   -> "C:\\"
 *
 * Returns null if no separator is found.
 */
export function parentDirectoryOf(filePath: string): string | null {
	const lastSep = Math.max(filePath.lastIndexOf("/"), filePath.lastIndexOf("\\"));
	if (lastSep < 0) return null;

	// POSIX root, e.g. "/video.mp4" -> "/"
	if (lastSep === 0) return filePath[0];

	// Windows drive root, e.g. "C:\\video.mp4" -> "C:\\"
	if (lastSep === 2 && /^[A-Za-z]:[/\\]/.test(filePath)) {
		return filePath.slice(0, lastSep + 1);
	}

	return filePath.slice(0, lastSep);
}

/**
 * Returns the remembered export folder as `string | undefined`, suitable for
 * passing directly to IPC handlers that treat absence as "use the default".
 */
export function getExportFolder(): string | undefined {
	return loadUserPreferences().exportFolder ?? undefined;
}

/**
 * Persist user preferences to localStorage.
 * Only the explicitly provided fields are updated.
 */
export function saveUserPreferences(partial: Partial<UserPreferences>): void {
	const current = loadUserPreferences();
	const merged = { ...current, ...partial };
	try {
		localStorage.setItem(PREFS_KEY, JSON.stringify(merged));
	} catch {
		// localStorage may be unavailable (e.g. private browsing quota exceeded)
	}
}