import "./mithril.min.js";

function fa_solid_icon(settings, name) {
	if (settings.fontawesome_svg_path) {
		// modify upstream svg to start with `<svg id="root" ...>`
		return m("svg.cte-icon", m("use", {href: `${settings.fontawesome_svg_path}/${name}-solid.svg#root`}));
	} else {
		return m(`i.fa-solid.fa-${name}.cte-icon`)
	}
}

const is_mobile = /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);

var AppointmentImage = {
	view: function(vnode) {
		const {item, settings} = vnode.attrs;
		const image_url = item.base.image?.fileUrl ?? (is_mobile ? default_image_mobile : null) ?? settings.default_image;

		return m(".cte-image",
			image_url ? m(
				"img",
				{
					src: image_url,
					alt: item.base.caption,
				},
			) : null,
		)
	}
}

// Options for date and time formatting
const fmtoptions_date = { weekday: 'short', day: 'numeric', month: 'long', year: 'numeric', timeZone: 'Europe/Berlin' };
const fmtoptions_date_short = { day: 'numeric', month: 'numeric', year: 'numeric', timeZone: 'Europe/Berlin' };
const fmtoptions_date_utc = { weekday: 'short', day: 'numeric', month: 'long', year: 'numeric', timeZone: 'UTC' };
const fmtoptions_time = { hour: '2-digit', minute: '2-digit', timeZone: 'Europe/Berlin' };
const fmt_date = new Intl.DateTimeFormat('de-DE', fmtoptions_date);
const fmt_date_short = new Intl.DateTimeFormat('de-DE', fmtoptions_date_short);
const fmt_date_utc = new Intl.DateTimeFormat('de-DE', fmtoptions_date_utc);
const fmt_time = new Intl.DateTimeFormat('de-DE', fmtoptions_time);

function display_date_utc(date, content) {
	const repr = date.toISOString().split("T")[0];
	return m("time", {datetime: repr}, content);
}

function display_date_local(date, content) {
	const [d, m, y] = fmtoptions_date_short.format(date).split(".");
	const repr = [y, m, d].join("-");
	return m("time", {datetime: repr}, content);
}

function display_datetime(date, content) {
	const repr = date.toISOString();
	return m("time", {datetime: repr}, content);
}

function display_event_date(item) {
	const start = new Date(item.calculated.startDate);
	const end = new Date(item.calculated.endDate);

	const start_date = fmt_date.format(start);
	const end_date = fmt_date.format(end);
	const start_time = fmt_time.format(start);
	const end_time = fmt_time.format(end);

	if (start === end) {
		return display_datetime(start, `${start_date}, ${start_time}`);
	}

	if (start_time === "00:00" && end_time === "00:00") {
		// localtime "all-day" event
		const end_day = new Date(end.valueOf() - 86400);
		const end_day_date = fmt_date.format(end_day);
		if (start_date === end_day_date) {
			return display_date_local(start, start_date);
		} else {
			return m("span.timerange", display_date_local(start, start_date), " - ", display_date_local(end_day, end_day_date));
		}
	}

	if (start.getUTCHours() === 0 && start.getUTCMinutes() === 0 && end.getUTCHours() === 0 && end.getUTCMinutes() === 0) {
		// UTC "all-day" event
		const end_day = new Date(end.valueOf() - 86400);
		const utc_start_date = fmt_date_utc.format(start);
		const utc_end_day_date = fmt_date_utc.format(end_day);
		if (utc_start_date === utc_end_day_date) {
			return display_date_utc(start, utc_start_date);
		} else {
			return m("span.timerange", display_date_utc(start, utc_start_date), " - ", display_date_utc(end_day, utc_end_day_date));
		}
	}

	if (start_date === end_date) {
		return m("span.timerange", display_datetime(start, `${start_date}, ${start_time}`), " - ", display_datetime(end, end_time));
	} else {
		return m(
			"span.timerange",
			display_datetime(start, `${start_date}, ${start_time}`),
			" - ",
			display_datetime(end, `${end_date}, ${end_time}`)
		);
	}
}

function format_ICS_text(text) {
	return text.replace(/[\\,;]/g, "\\$&") // escape backslash and separators
		.replace(/\n/g, "\\n") // escape newline
		.replace(/[\x00-\x1f]+/g, " ") // replace control characters with whitespace
	;
}

function format_ICS_date(date) {
	if (date) {
		date = new Date(date);
	} else {
		date = new Date(); // default to "now"
	}
	// remove "-" and ":" separators (but keep "T"), and drop microseconds
	return date.toISOString().replace(/-|:|\.\d+/g, "");
}

function createICSLink(item, settings) {
	const start = format_ICS_date(item.calculated.startDate);
	const end = format_ICS_date(item.calculated.endDate);

	const summary = item.base.caption;
	const description = item.base.information || "";
	const location = item.base.address?.meetingAt || "";

	// Escape special characters for ICS fields
	const escapedSummary = format_ICS_text(summary /* .replace(/['"]/g, "") */);
	const escapedDescription = format_ICS_text(description /* .replace(/['"]/g, "") */);
	const escapedLocation = format_ICS_text(location);

	const icsContent = `BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//churchtools-next-events//EN
BEGIN:VEVENT
UID:appointment-${item.base.id}@${window.location.hostname}
CREATED:${format_ICS_date(item.base.meta?.createdDate)}
LAST-MODIFIED:${format_ICS_date(item.base.meta?.modifiedDate)}
DTSTART:${start}
DTEND:${end}
SUMMARY:${escapedSummary}
DESCRIPTION:${escapedDescription}
LOCATION:${escapedLocation}
END:VEVENT
END:VCALENDAR
`;

	const blob = new Blob([icsContent], { type: 'text/calendar' });
	const url = URL.createObjectURL(blob);

	return m(
		"a",
		{
			href: url,
			download: "event.ics",
		},
		[
			fa_solid_icon(settings, "calendar-plus"),
			is_mobile ? "" : " Termin herunterladen",
		]
	)
}

var AppointmentHeader = {
	view: function(vnode) {
		const {item, settings} = vnode.attrs;

		return m(".cte-info-header", [
			m("span.cte-date", display_event_date(item)),
			m("span.cte-download", createICSLink(item, settings)),
		]);
	}
}

var AppointmentDescription = {
	view: function(vnode) {
		const {item, settings} = vnode.attrs;
		const note_parts = [];
		if (item.base.note) {
			note_parts.push(item.base.note);
		}
		if (item.base.address?.meetingAt) {
			note_parts.push(item.base.address.meetingAt);
		}
		return m(".cte-description", [
			m("h1", item.base.caption),
			m("h2", note_parts.join(" | ")),
		]);
	}
}

/* find `http://`, `https://` and `www.` links
 * - requires whitespace, parantheses `(, `)` or line start/end before and after it
 * - find non-links as first capture, links as second capture (might be empty)
 */
const REGEX_FIND_LINKS = /(?<=^|[\s()])(?:https?:\/\/|www\.)[^\s()*]*(?=[()\s]|$)/;
const REGEX_FIND_LINKS_CONT = /(?<=[\s()])(?:https?:\/\/|www\.)[^\s()*]*(?=[()\s]|$)/;

function* format_links(part) {
	let regex = REGEX_FIND_LINKS;
	while (true) {
		const match = part.match(regex);
		regex = REGEX_FIND_LINKS_CONT;
		const normal = part.substring(0, match?.index ?? part.length);
		yield normal;
		if (!match) {
			return;
		}
		part = part.substring(match.index + match[0].length);
		const url = match[0];
		yield m("a", {href: url, target: "_blank"}, url);
	}
}

/* find `*...*` highlighted text:
 * - requires whitespace or line start/end before and after it
 * - requires non-space on the inside as first and last character
 * - `*` not allowed inside
 * - find non-highlighted text as first capture, highlighted as second capture (might be empty)
 */
const REGEX_FIND_HIGHLIGHTED = /(?<=^|\s)\*[^*\s](?:[^*]*[^*\s])?\*(?=\s|$)/;
const REGEX_FIND_HIGHLIGHTED_CONT = /(?<=\s)\*[^*\s](?:[^*]*[^*\s])?\*(?=\s|$)/;

function* format_highlights_and_links(line) {
	let regex = REGEX_FIND_HIGHLIGHTED;
	while (true) {
		const match = line.match(regex);
		regex = REGEX_FIND_HIGHLIGHTED_CONT;
		const normal = line.substring(0, match?.index ?? line.length);
		for (const part of format_links(normal)) {
			yield part;
		}
		if (!match) {
			return;
		}
		line = line.substring(match.index + match[0].length);
		yield m("strong", ["*", ...format_links(match[0].slice(1, -1)), "*"])
	}
}

function format_information(item) {
	const information = item.base.information || "";
	const paragraphs = [];
	let cur_lines = [];

	for (const line of information.split(/\r?\n/)) {
		if (!line.trim()) {
			// split paragraphs
			if (cur_lines.length) {
				paragraphs.push(cur_lines);
				cur_lines = [];
			}
			continue;
		}
		/* find `*...*` highlighted text */
		const line_parts = [];
		if (cur_lines.length) {
			line_parts.push(m("br"));
		}
		line_parts.push(...format_highlights_and_links(line));
		cur_lines.push(m("[", line_parts));
	}
	if (cur_lines.length) {
		paragraphs.push(cur_lines);
	}
	return m("[", paragraphs.map((para) => m("p", para)));
}

var AppointmentLocation = {
	view: function(vnode) {
		const {item, settings} = vnode.attrs;

		const location_parts = [];
		if (item.base.address?.meetingAt) {
			location_parts.push(item.base.address.meetingAt);
		}
		if (item.base.address?.street) {
			location_parts.push(item.base.address.street);
		}
		const location = location_parts.join(", ");

		if (!location) {
			return m("[");
		}

		return m("p", [
			fa_solid_icon(settings, "location-dot"),
			" ",
			location,
		]);
	}
}

var AppointmentLink = {
	view: function(vnode) {
		const {item, settings} = vnode.attrs;
		if (!item.base.link) {
			return m("[");
		}

		let url = item.base.link;
		if (!url.startsWith("http")) {
			url = "https://" + url;
		}

		return m("p", [
			fa_solid_icon(settings, "link"),
			" ",
			m("a", {href: url, target: "_blank"}, item.base.link),
		])
	}
}

function AppointmentDetails() {
	let collapsed = true;

	function toggle() {
		collapsed = !collapsed;
	}

	return {
		view: function(vnode) {
			const {item, settings} = vnode.attrs;

			const show_details = item.base.information /* || item.base.address?.meetingAt || item.base.address?.street */ || item.base.link;

			if (!show_details) {
				return m("[");
			}
			return m(
				".cte-details-collapser",
				{
					class: collapsed ? "collapsed" : "",
				},
				[
					m(".cte-details", [
						m(".cte-information-group", [
							m("h3.cte-information-label", "Beschreibung"),
							m(".cte-information", [
								format_information(item),
								m(AppointmentLocation,{item, settings}),
								m(AppointmentLink, {item, settings}),
							]),
						]),
					]),
					m(
						"button.toggle-collapse",
						{onclick: toggle},
						collapsed ? "Details anzeigen" : "Details verbergen",
						" ",
						fa_solid_icon(settings, collapsed ? "chevron-down" : "chevron-up"),
					),
				],
			);
		}
	}
};

var Appointment = {
	view: function(vnode) {
		const {item, settings} = vnode.attrs;

		return m(".cte-event", [
			m(".cte-summary", [
				m(AppointmentImage, {item, settings}),
				m(".cte-info", [
					m(AppointmentHeader, {item, settings}),
					m(AppointmentDescription, {item, settings}),
				]),
			]),
			m(AppointmentDetails, {item, settings}),
		])
	},
};

async function load_events(dom_node, defaults) {
	if (dom_node.dataset.cteActive) {
		return;
	}
	dom_node.dataset.cteActive = true;

	const settings = {
		instance: dom_node.dataset.cteInstance ?? defaults.instance,
		days: dom_node.dataset.cteDays ?? defaults.days ?? 31,
		calendar_regex: dom_node.dataset.cteCalendarRegex ?? defaults.calendar_regex,
		event_regex: dom_node.dataset.cteEventRegex ?? defaults.event_regex,
		limit: dom_node.dataset.cteLimit ?? defaults.limit ?? 5,
		default_image: dom_node.dataset.cteDefaultImage ?? defaults.default_image,
		default_image_mobile: dom_node.dataset.cteDefaultImageMobile ?? defaults.default_image_mobile,
		fontawesome_svg_path: dom_node.dataset.cteFontawesomeSvgPath ?? defaults.fontawesome_svg_path,
	};

	function format_date(date) {
		return date.toISOString().split('T')[0];
	}

	const req_config = {
		credentials: "omit",
		mode: "cors",
	}

	const r_cal_regex = new RegExp(settings.calendar_regex, "i");
	const r_event_regex = new RegExp(settings.event_regex, "i");
	const all_calendars = (await (await fetch(settings.instance + "/api/calendars", req_config)).json()).data;
	const calendars = all_calendars.filter((calendar) => r_cal_regex.exec(calendar.name));
	const calendar_ids = calendars.map((calendar) => calendar.id);

	let appointments;

	if (calendar_ids.length) {
		const filters = calendar_ids.map((cal_id) => `calendar_ids[]=${cal_id}`);
		const from = new Date();
		filters.push(`from=${format_date(from)}`);
		const to = new Date(from.valueOf() + settings.days * 86400 * 1000);
		filters.push(`to=${format_date(to)}`);
		const query = filters.join("&");
		const all_appointments = (await (await fetch(settings.instance + `/api/calendars/appointments?${query}`, req_config)).json()).data;
		appointments = all_appointments.filter((appointment) => r_event_regex.exec(appointment.base.title));

		if (appointments.length > settings.limit) {
			appointments.length = settings.limit;
		}
	} else {
		appointments = [];
	}

	const Appointments = {
		view: function(vnode) {
			return m("[", appointments.map((item) => m(Appointment, {item, settings})));
		}
	};

	m.mount(dom_node, Appointments);
}

async function load_all_events(defaults) {
	await Promise.all(Array.from(document.querySelectorAll(".cte-events")).map((node) => load_events(node, defaults)));
}

export { load_all_events };