/* 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 Affero 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <err.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>
#include <time.h>

#include "server.h"

int eventsGap = 3600;
int eventsOverlap = 30;
int eventsLimit = 50;

static const char *timestamp(time_t time) {
	static char stamp[sizeof("0000-00-00T00:00:00")];
	strftime(stamp, sizeof(stamp), "%FT%T", gmtime(&time));
	return stamp;
}

static enum kcgi_err
dateForm(struct khtmlreq *html, struct Scope scope, const char *_time) {
	struct tm tm = {0};
	if (!strptime(_time, "%F", &tm)) {
		tm = *gmtime(&(time_t) { time(NULL) });
	}
	char date[sizeof("0000-00-00")];
	strftime(date, sizeof(date), "%F", &tm);
	return 0
		|| khtml_attr(
			html, KELEM_FORM,
			KATTR_METHOD, "get",
			KATTR_ACTION, Pages[Events],
			KATTR__MAX
		)
		|| htmlScopeFields(html, scope)
		|| khtml_attr(
			html, KELEM_INPUT,
			KATTR_TYPE, "date",
			KATTR_NAME, Keys[After].name,
			KATTR_VALUE, date,
			KATTR__MAX
		)
		|| khtml_attr(
			html, KELEM_INPUT,
			KATTR_TYPE, "submit",
			KATTR_VALUE, "Jump",
			KATTR__MAX
		)
		|| khtml_closeelem(html, 1);
}

const char *EventsTopicQuery = SQL(
	SELECT topics.topic
	FROM topics
	JOIN contexts USING (context)
	WHERE contexts.network = :network
		AND contexts.name = :context
		AND contexts.query <= NOT :public
		AND topics.time <= strftime('%s', :time)
	ORDER BY topics.time DESC
	LIMIT 1;
);

const char *EventsAfterQuery = SQL(
	SELECT
		events.event,
		events.time,
		events.type,
		names.nick,
		names.user,
		names.host,
		events.target,
		events.message
	FROM events
	JOIN contexts USING (context)
	JOIN names USING (name)
	WHERE contexts.network = :network
		AND contexts.name = :context
		AND contexts.query <= NOT :public
		AND events.time >= strftime('%s', :time)
	ORDER BY events.time, events.event
	LIMIT :limit;
);

const char *EventsBeforeQuery = SQL(
	WITH before AS (
		SELECT
			events.event,
			events.time,
			events.type,
			names.nick,
			names.user,
			names.host,
			events.target,
			events.message
		FROM events
		JOIN contexts USING (context)
		JOIN names USING (name)
		WHERE contexts.network = :network
			AND contexts.name = :context
			AND contexts.query <= NOT :public
			AND events.time < strftime('%s', :time)
		ORDER BY events.time DESC
		LIMIT :limit
	)
	SELECT * FROM before
	ORDER BY time, event;
);

enum kcgi_err eventsPage(struct kreq *req) {
	struct Scope scope = pageScope(req);
	if (!scope.network || !scope.context) return httpFail(req, KHTTP_400);

	if (!req->fieldmap[After] && !req->fieldmap[Before]) {
		char *url = khttp_urlpart(
			NULL, NULL, Pages[Events],
			Keys[Network].name, scope.network,
			Keys[Context].name, scope.context,
			Keys[Before].name, timestamp(time(NULL)),
			NULL
		);
		if (!url) err(EX_OSERR, "khttp_urlpart");
		enum kcgi_err error = httpRedirect(req, url);
		free(url);
		return error;
	}

	const char *time = req->fieldmap[Before]
		? req->fieldmap[Before]->parsed.s
		: req->fieldmap[After]->parsed.s;

	enum kcgi_err error = httpHead(req, KHTTP_200, KMIME_TEXT_HTML);
	if (req->method == KMETHOD_HEAD) return error;

	struct khtmlreq html;
	error = error
		|| khttp_body(req)
		|| khtml_open(&html, req, 0)
		|| htmlHead(&html, scope.context)
		|| htmlNav(&html, scope)
		|| dateForm(&html, scope, time)
		|| khtml_elem(&html, KELEM_TABLE);
	if (error) return error;

	sqlite3_reset(stmt.topic);
	dbBindText(stmt.topic, ":network", scope.network);
	dbBindText(stmt.topic, ":context", scope.context);
	dbBindText(stmt.topic, ":time", time);
	dbBindInt(stmt.topic, ":public", contextsPublic);

	int result = sqlite3_step(stmt.topic);
	if (result == SQLITE_ROW) {
		error = 0
			|| khtml_elem(&html, KELEM_THEAD)
			|| khtml_attr(&html, KELEM_TR, KATTR_CLASS, "topic", KATTR__MAX)
			|| khtml_attr(&html, KELEM_TH, KATTR_COLSPAN, "3", KATTR__MAX)
			|| khtml_puts(&html, sqlite3_column_text(stmt.topic, 0))
			|| khtml_closeelem(&html, 3);
		if (error) return error;
		result = sqlite3_step(stmt.topic);
	}
	if (result != SQLITE_DONE) errx(EX_SOFTWARE, "%s", sqlite3_errmsg(db));

	sqlite3_stmt *events = stmt.eventsAfter;
	if (req->fieldmap[Before]) events = stmt.eventsBefore;

	sqlite3_reset(events);
	dbBindText(events, ":network", scope.network);
	dbBindText(events, ":context", scope.context);
	dbBindText(events, ":time", time);
	dbBindInt(events, ":public", contextsPublic);
	dbBindInt(events, ":limit", eventsLimit);

	int rows;
	time_t prevTime = 0;
	int64_t prevEvent = 0;
	for (rows = 0; SQLITE_ROW == (result = sqlite3_step(events)); ++rows) {
		int i = 0;
		struct Event event = {0};
		event.event = sqlite3_column_int64(events, i++);
		event.time = sqlite3_column_int64(events, i++);
		event.type = sqlite3_column_int(events, i++);
		event.nick = sqlite3_column_text(events, i++);
		event.user = sqlite3_column_text(events, i++);
		event.host = sqlite3_column_text(events, i++);
		event.target = sqlite3_column_text(events, i++);
		event.message = sqlite3_column_text(events, i++);

		if (!rows) {
			char *base = khttp_urlpart(
				NULL, NULL, Pages[Events],
				Keys[Network].name, scope.network,
				Keys[Context].name, scope.context,
				Keys[Before].name, timestamp(event.time + eventsOverlap),
				NULL
			);
			if (!base) err(EX_OSERR, "khttp_urlpart");

			char *href = NULL;
			asprintf(&href, "%s#%" PRId64, base, event.event);
			if (!href) err(EX_OSERR, "asprintf");
			free(base);

			error = 0
				|| khtml_attr(&html, KELEM_TR, KATTR_CLASS, "page", KATTR__MAX)
				|| khtml_attr(&html, KELEM_TH, KATTR_COLSPAN, "3", KATTR__MAX)
				|| khtml_attr(&html, KELEM_A, KATTR_HREF, href, KATTR__MAX)
				|| khtml_puts(&html, "Earlier messages")
				|| khtml_closeelem(&html, 3);
			free(href);
			if (error) return error;
		}

		if (prevTime && event.time - prevTime >= eventsGap) {
			error = 0
				|| khtml_attr(&html, KELEM_TR, KATTR_CLASS, "gap", KATTR__MAX)
				|| khtml_attr(&html, KELEM_TH, KATTR_COLSPAN, "3", KATTR__MAX)
				|| khtml_puts(&html, "...")
				|| khtml_closeelem(&html, 2);
			if (error) return error;
		}
		prevEvent = event.event;
		prevTime = event.time;

		error = htmlEvent(&html, scope, event);
		if (error) return error;
	}
	if (result != SQLITE_DONE) errx(EX_SOFTWARE, "%s", sqlite3_errmsg(db));

	if (rows == eventsLimit || req->fieldmap[Before]) {
		char *href = khttp_urlpart(
			NULL, NULL, Pages[Events],
			Keys[Network].name, scope.network,
			Keys[Context].name, scope.context,
			Keys[After].name, timestamp(prevTime - eventsOverlap),
			NULL
		);
		if (!href) err(EX_OSERR, "khttp_urlpart");
		error = 0
			|| khtml_attr(&html, KELEM_TR, KATTR_CLASS, "page", KATTR__MAX)
			|| khtml_attr(&html, KELEM_TH, KATTR_COLSPAN, "3", KATTR__MAX)
			|| khtml_attr(&html, KELEM_A, KATTR_HREF, href, KATTR__MAX)
			|| khtml_puts(&html, "Later messages")
			|| khtml_closeelem(&html, 3);
		free(href);
		if (error) return error;
	}

	if (!rows) {
		error = 0
			|| khtml_elem(&html, KELEM_TR)
			|| khtml_attr(&html, KELEM_TH, KATTR_COLSPAN, "3", KATTR__MAX)
			|| khtml_puts(&html, "No matching messages");
		if (error) return error;
	}

	return htmlFooter(&html) || khtml_close(&html);
}