/* Copyright (C) 2020  C. McEnroe <june@causal.agency>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <time.h>

#include "archive.h"

static int htmlAddress(FILE *file, const char *class, struct Address addr) {
	const char *template;
	if (addr.host) {
		template = TEMPLATE(
			<li><address class="[class]">[name]</address></li>
		);
	} else if (addr.mailbox) {
		template = TEMPLATE(
			<li>
				<address class="[class] group">[mailbox]</address>
				<ul class="group">
		);
	} else {
		template = TEMPLATE(
				</ul>
			</li>
		);
	}
	struct Variable vars[] = {
		{ "class", class },
		{ "name", addressName(addr) },
		{ "mailbox", addr.mailbox },
		{0},
	};
	return templateRender(file, template, vars, escapeXML);
}

static int
htmlAddressList(FILE *file, const char *class, struct AddressList list) {
	if (!list.len) return 0;
	const char *template = TEMPLATE(
		<ul class="recipient [class]">
	);
	struct Variable vars[] = {
		{ "class", class },
		{0},
	};
	int error = templateRender(file, template, vars, escapeXML);
	if (error) return error;
	for (size_t i = 0; i < list.len; ++i) {
		error = htmlAddress(file, class, list.addrs[i]);
		if (error) return error;
	}
	return templateRender(file, TEMPLATE(</ul>), NULL, NULL);
}

static char *htmlMailto(const struct Envelope *envelope) {
	const char *template = {
		"mailto:[mailbox]@[host]?subject=[re][subject]&In-Reply-To=[messageID]"
	};
	struct Variable vars[] = {
		{ "mailbox", envelope->from.mailbox },
		{ "host", envelope->from.host },
		{ "re", (strncmp(envelope->subject, "Re: ", 4) ? "Re: " : "") },
		{ "subject", envelope->subject },
		{ "messageID", envelope->messageID },
		{0},
	};
	return templateURL(template, vars);
}

static char *htmlFragment(const struct Envelope *envelope) {
	struct Variable vars[] = {
		{ "messageID", envelope->messageID },
		{0},
	};
	return templateURL("#[messageID]", vars);
}

static char *htmlMbox(const struct Envelope *envelope) {
	struct Variable vars[] = {
		{ "name", pathSafe(envelope->messageID) },
		{0},
	};
	return templateURL("../message/[name].mbox", vars);
}

int htmlMessageOpen(FILE *file, const struct Envelope *envelope) {
	// TODO: Conditionally include mailto: link.
	const char *template = TEMPLATE(
		<article class="message" id="[messageID]">
		<header>
			<h2 class="subject"><a href="[fragment]">[subject]</a></h2>
			<address class="from">
				<a href="[mailto]">[from]</a>
			</address>
			<time datetime="[utc]">[date]</time>
			<nav>
				<ul>
					<li><a href="[mbox]">mbox</a></li>
				</ul>
			</nav>
	);
	char *fragment = htmlFragment(envelope);
	char *mailto = htmlMailto(envelope);
	char *mbox = htmlMbox(envelope);
	char utc[sizeof("0000-00-00T00:00:00Z")];
	strftime(utc, sizeof(utc), "%FT%TZ", gmtime(&envelope->time));
	struct Variable vars[] = {
		{ "messageID", envelope->messageID },
		{ "fragment", fragment },
		{ "subject", envelope->subject },
		{ "mailto", mailto },
		{ "from", addressName(envelope->from) },
		{ "utc", utc },
		{ "date", envelope->date },
		{ "mbox", mbox },
		{0},
	};
	int error = 0
		|| templateRender(file, template, vars, escapeXML)
		|| htmlAddressList(file, "to", envelope->to)
		|| htmlAddressList(file, "cc", envelope->cc)
		|| templateRender(file, TEMPLATE(</header>), NULL, NULL);
	free(mailto);
	free(fragment);
	free(mbox);
	return error;
}

int htmlInline(FILE *file, const struct BodyPart *part, const char *content) {
	// TODO: Include Content-Id as id?
	// TODO: format=flowed.
	// TODO: Process quoting.
	// TODO: Highlight patches.
	const char *template = TEMPLATE(
		<pre lang="[lang]">[content]</pre>
	);
	const char *lang = "";
	// FIXME: part->language should be more structured.
	if (part->language.len && part->language.ptr[0].type == String) {
		lang = part->language.ptr[0].string;
	}
	struct Variable vars[] = {
		{ "lang", lang },
		{ "content", content },
		{0},
	};
	return templateRender(file, template, vars, escapeXML);
}

int htmlMessageClose(FILE *file) {
	return templateRender(file, TEMPLATE(</article>), NULL, NULL);
}

const char *htmlTitle;

static char *htmlThreadURL(const struct Envelope *envelope) {
	struct Variable vars[] = {
		{ "name", pathSafe(envelope->messageID) },
		{0},
	};
	return templateURL("[name]", vars);
}

int htmlThreadHead(FILE *file, const struct Envelope *envelope) {
	const char *template = TEMPLATE(
		<!DOCTYPE html>
		<meta charset="utf-8">
		<title>[subject] &middot; [title]</title>
		<link rel="alternate" type="application/atom+xml" href="[url].atom">
		<link rel="alternate" type="application/mbox" href="[url].mbox">
	);
	char *url = htmlThreadURL(envelope);
	struct Variable vars[] = {
		{ "subject", envelope->subject },
		{ "title", htmlTitle },
		{ "url", url },
		{0},
	};
	int error = templateRender(file, template, vars, escapeXML);
	free(url);
	return error;
}

int htmlThreadOpen(FILE *file, const struct Envelope *envelope) {
	const char *template = TEMPLATE(
		<header class="thread">
			<h1>[subject]</h1>
			<nav>
				<ul>
					<li><a href="[url].atom">Atom</a></li>
					<li><a href="[url].mbox">mbox</a></li>
				</ul>
			</nav>
		</header>
		<main class="thread">
	);
	char *url = htmlThreadURL(envelope);
	struct Variable vars[] = {
		{ "subject", envelope->subject },
		{ "url", url },
		{0},
	};
	int error = templateRender(file, template, vars, escapeXML);
	free(url);
	return error;
}

static size_t threadCount(struct List thread) {
	size_t count = 0;
	for (size_t i = 0; i < thread.len; ++i) {
		if (thread.ptr[i].type == List) {
			count += threadCount(thread.ptr[i].list);
		} else {
			count++;
		}
	}
	return count;
}

int htmlSubthreadOpen(FILE *file, struct List thread) {
	const char *template = TEMPLATE(
		<details class="subthread" open>
			<summary>[replies] repl[ies]</summary>
	);
	size_t count = threadCount(thread);
	char replies[32];
	snprintf(replies, sizeof(replies), "%zu", count);
	struct Variable vars[] = {
		{ "replies", replies },
		{ "ies", (count > 1 ? "ies" : "y") },
		{0},
	};
	return templateRender(file, template, vars, escapeXML);
}

int htmlSubthreadClose(FILE *file) {
	return templateRender(file, TEMPLATE(</details>), NULL, NULL);
}

int htmlThreadClose(FILE *file) {
	return templateRender(file, TEMPLATE(</main>), NULL, NULL);
}