import { fail } from '@sveltejs/kit';
import { db, peaksNearBounds, recordAscent } from '$lib/server/db';
import { matchPeaks, parseGpx } from '$lib/server/gpx';
import type { Actions } from './$types';

/** A "name" that is really just a date or timestamp, e.g. "2023-10-03 17:39:35". */
const DATE_ONLY_NAME =
	/^\d{4}[-/.]\d{1,2}[-/.]\d{1,2}([ T](\d{1,2}[:.]\d{2}([:.]\d{2})?|\d{4,6}))?Z?$/;

/** Infer an activity type from average moving speed when the GPX doesn't say. */
function inferType(gpx: { distance_m: number; moving_s: number | null }): string | null {
	if (!gpx.moving_s || gpx.moving_s < 60) return null;
	const kmh = (gpx.distance_m / gpx.moving_s) * 3.6;
	if (kmh >= 13) return 'ride';
	if (kmh >= 7) return 'run';
	return 'hike';
}

/** "Morning Hike", "Evening Run", or "Hike on 3 Oct 2023" when there's no start time. */
function generateName(type: string, start: string | null, date: string | null): string {
	const capitalized = type.charAt(0).toUpperCase() + type.slice(1);
	if (start) {
		const hour = new Date(start).getUTCHours();
		const period =
			hour >= 4 && hour < 11
				? 'Morning'
				: hour >= 11 && hour < 14
					? 'Lunch'
					: hour >= 14 && hour < 18
						? 'Afternoon'
						: hour >= 18 && hour < 22
							? 'Evening'
							: 'Night';
		return `${period} ${capitalized}`;
	}
	if (date) {
		const nice = new Date(date + 'T12:00:00').toLocaleDateString('en-GB', {
			day: 'numeric',
			month: 'short',
			year: 'numeric'
		});
		return `${capitalized} on ${nice}`;
	}
	return capitalized;
}

/**
 * Parse export-style filenames like
 * "2018-01-11 141322 - Run - Afternoon Run.gpx" (Date - Type - Name).
 */
function parseFilename(
	filename: string
): { date: string; type: string; name: string } | null {
	const base = filename.replace(/\.gpx$/i, '');
	const parts = base.split(' - ');
	if (parts.length < 3) return null;
	const dateMatch = parts[0].match(/^(\d{4}-\d{2}-\d{2})(\s+\d{4,6})?$/);
	if (!dateMatch) return null;
	return {
		date: dateMatch[1],
		type: parts[1].trim().toLowerCase(),
		name: parts.slice(2).join(' - ').trim()
	};
}

export const actions: Actions = {
	default: async ({ request, locals }) => {
		const userId = locals.user!.id;
		const form = await request.formData();
		const files = form.getAll('gpx').filter((f): f is File => f instanceof File && f.size > 0);
		if (files.length === 0) return fail(400, { error: 'No GPX files selected.' });

		const uploaded: { id: number; name: string; newPeaks: string[] }[] = [];
		const errors: string[] = [];

		const insert = db.prepare(`
			INSERT INTO activities
				(user_id, name, type, date, distance_m, duration_s, moving_s,
				 elev_gain_m, elev_loss_m, elev_min_m, elev_max_m, points, bounds)
			VALUES
				(@user_id, @name, @type, @date, @distance_m, @duration_s, @moving_s,
				 @elev_gain_m, @elev_loss_m, @elev_min_m, @elev_max_m, @points, @bounds)
		`);

		for (const file of files) {
			try {
				const gpx = parseGpx(await file.text());
				const parsed = parseFilename(file.name);

				// a missing, "outdoor", or numeric (old Strava code) type gets inferred from pace
				let type = parsed?.type ?? gpx.type ?? '';
				if (!type || type === 'outdoor' || /^\d+$/.test(type)) {
					type = inferType(gpx) ?? 'outdoor';
				}
				// a name that is just a date/timestamp gets a friendly generated one
				let name = parsed?.name ?? gpx.name ?? file.name.replace(/\.gpx$/i, '');
				if (!name.trim() || DATE_ONLY_NAME.test(name.trim())) {
					name = generateName(type, gpx.start, gpx.date ?? parsed?.date ?? null);
				}

				const result = insert.run({
					user_id: userId,
					name,
					type,
					date: gpx.date ?? parsed?.date ?? null,
					distance_m: gpx.distance_m,
					duration_s: gpx.duration_s,
					moving_s: gpx.moving_s,
					elev_gain_m: gpx.elev_gain_m,
					elev_loss_m: gpx.elev_loss_m,
					elev_min_m: gpx.elev_min_m,
					elev_max_m: gpx.elev_max_m,
					points: JSON.stringify(gpx.points),
					bounds: JSON.stringify(gpx.bounds)
				});
				const activityId = Number(result.lastInsertRowid);

				const nearby = peaksNearBounds(gpx.bounds);
				const summited = matchPeaks(gpx.points, nearby);
				const newPeaks: string[] = [];
				for (const peak of summited) {
					if (recordAscent(userId, peak.id, activityId, gpx.date)) newPeaks.push(peak.name);
				}

				uploaded.push({ id: activityId, name, newPeaks });
			} catch (err) {
				errors.push(`${file.name}: ${err instanceof Error ? err.message : 'could not parse'}`);
			}
		}

		if (uploaded.length === 0) return fail(422, { error: errors.join(' ') });
		return { uploaded, errors };
	}
};