/* 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 <assert.h>
#include <ctype.h>
#include <err.h>
#include <inttypes.h>
#include <regex.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <time.h>

#include "server.h"

bool htmlHideHost;
const char *htmlStylesheet = "stylesheet.css";

static enum kcgi_err htmlCSS(struct khtmlreq *html, struct kreq *req) {
	if (req->fieldmap[Export]) {
		return 0
			|| khtml_elem(html, KELEM_STYLE)
			|| khttp_puts(req, CSS)
			|| khtml_closeelem(html, 1);
	} else {
		return khtml_attr(
			html, KELEM_LINK,
			KATTR_REL, "stylesheet",
			KATTR_HREF, htmlStylesheet,
			KATTR__MAX
		);
	}
}

enum kcgi_err
htmlHead(struct khtmlreq *html, struct kreq *req, const char *title) {
	return khtml_elem(html, KELEM_DOCTYPE)
		|| khtml_attr(html, KELEM_META, KATTR_CHARSET, "utf-8", KATTR__MAX)
		|| khtml_elem(html, KELEM_TITLE)
		|| khtml_puts(html, title)
		|| khtml_closeelem(html, 1)
		|| htmlCSS(html, req)
		|| khtml_elem(html, KELEM_H1)
		|| khtml_puts(html, title)
		|| khtml_closeelem(html, 1);
}

enum kcgi_err
htmlHidden(struct khtmlreq *html, struct kreq *req, enum Key key) {
	if (!req->fieldmap[key]) return KCGI_OK;
	return khtml_attr(
		html, KELEM_INPUT,
		KATTR_TYPE, "hidden",
		KATTR_NAME, Keys[key].name,
		KATTR_VALUE, req->fieldmap[key]->val,
		KATTR__MAX
	);
}

enum kcgi_err htmlNav(struct khtmlreq *html, struct kreq *req) {
	if (req->fieldmap[Export]) return KCGI_OK;

	enum kcgi_err error = 0
		|| khtml_elem(html, KELEM_NAV)
		|| khtml_elem(html, KELEM_OL)
		|| khtml_elem(html, KELEM_LI)
		|| khtml_attr(html, KELEM_A, KATTR_HREF, Pages[Networks], KATTR__MAX)
		|| khtml_puts(html, "Networks")
		|| khtml_closeelem(html, 2);
	if (error) return error;

	const char *network = NULL;
	const char *context = NULL;
	if (req->fieldmap[Network]) {
		network = req->fieldmap[Network]->parsed.s;
		if (req->fieldmap[Context]) {
			context = req->fieldmap[Context]->parsed.s;
		}
	}

	if (network) {
		char *href = khttp_urlpart(
			NULL, NULL, Pages[Contexts],
			Keys[Network].name, network,
			NULL
		);
		if (!href) err(EX_OSERR, "khttp_urlpart");
		error = 0
			|| khtml_elem(html, KELEM_LI)
			|| khtml_attr(html, KELEM_A, KATTR_HREF, href, KATTR__MAX)
			|| khtml_puts(html, network)
			|| khtml_closeelem(html, 2);
		free(href);
		if (error) return error;
	}

	if (context) {
		const char *context = req->fieldmap[Context]->parsed.s;
		char *href = khttp_urlpart(
			NULL, NULL, Pages[Events],
			Keys[Network].name, network,
			Keys[Context].name, context,
			NULL
		);
		if (!href) err(EX_OSERR, "khttp_urlpart");
		error = 0
			|| khtml_elem(html, KELEM_LI)
			|| khtml_attr(html, KELEM_A, KATTR_HREF, href, KATTR__MAX)
			|| khtml_puts(html, context)
			|| khtml_closeelem(html, 2);
		free(href);
		if (error) return error;
	}

	const char *query = NULL;
	if (req->fieldmap[Query]) {
		query = req->fieldmap[Query]->parsed.s;
	}
	return 0
		|| khtml_closeelem(html, 1)
		|| khtml_attr(
			html, KELEM_FORM,
			KATTR_METHOD, "get",
			KATTR_ACTION, Pages[Search],
			KATTR__MAX
		)
		|| htmlHidden(html, req, Network)
		|| htmlHidden(html, req, Context)
		|| khtml_attr(
			html, KELEM_INPUT,
			KATTR_TYPE, "search",
			KATTR_NAME, Keys[Query].name,
			KATTR_VALUE, (query ? query : ""),
			KATTR__MAX
		)
		|| khtml_elem(html, KELEM_BUTTON)
		|| khtml_printf(
			html, "Search %s",
			(context ? context : network ? network : "")
		)
		|| khtml_closeelem(html, 3);
}

static enum kcgi_err
linkify(struct khtmlreq *html, const char *str, size_t len) {
	static const char *Pattern = "https?://([^[:space:]>\"()]|[(][^)]*[)])+";
	static regex_t regex;
	if (!regex.re_nsub) {
		int error = regcomp(&regex, Pattern, REG_EXTENDED);
		assert(!error);
	}

	regmatch_t match = {0};
	while (!regexec(&regex, str, 1, &match, 0)) {
		if ((size_t)match.rm_eo > len) break;

		char *href = strndup(&str[match.rm_so], match.rm_eo - match.rm_so);
		if (!href) err(EX_OSERR, "strndup");

		enum kcgi_err error = 0
			|| khtml_write(str, match.rm_so, html)
			|| khtml_attr(html, KELEM_A, KATTR_HREF, href, KATTR__MAX)
			|| khtml_write(&str[match.rm_so], match.rm_eo - match.rm_so, html)
			|| khtml_closeelem(html, 1);
		free(href);
		if (error) return error;

		str += match.rm_eo;
		len -= match.rm_eo;
	}
	if (len) return khtml_write(str, len, html);
	return KCGI_OK;
}

static const struct Style {
	int fg, bg;
	bool b, r, i, u;
} Default = { .fg = 99, .bg = 99 };

static enum kcgi_err htmlStyle(struct khtmlreq *html, struct Style style) {
	enum kcgi_err error = KCGI_OK;
	char class[sizeof("fg99")];
	if (style.fg != Default.fg) {
		snprintf(class, sizeof(class), "fg%02d", style.fg);
		error = error || khtml_attr(
			html, KELEM_SPAN,
			KATTR_CLASS, class,
			KATTR__MAX
		);
	}
	if (style.bg != Default.bg) {
		snprintf(class, sizeof(class), "bg%02d", style.bg);
		error = error || khtml_attr(
			html, KELEM_SPAN,
			KATTR_CLASS, class,
			KATTR__MAX
		);
	}
	if (style.b) error = error || khtml_elem(html, KELEM_B);
	if (style.r) error = error || khtml_elem(html, KELEM_MARK);
	if (style.i) error = error || khtml_elem(html, KELEM_I);
	if (style.u) error = error || khtml_elem(html, KELEM_U);
	return error;
}

enum kcgi_err htmlIRC(struct khtmlreq *html, const char *str) {
	enum kcgi_err error = khtml_attr(
		html, KELEM_SPAN,
		KATTR_CLASS, "irc",
		KATTR__MAX
	);
	if (error) return error;

	size_t top = khtml_elemat(html);
	struct Style style = Default;
	for (;;) {
		size_t len = strcspn(str, "\2\3\17\26\35\37");
		if (len) {
			error = 0
				|| khtml_closeto(html, top)
				|| htmlStyle(html, style)
				|| linkify(html, str, len);
			if (error) return error;
		}

		str += len;
		if (!*str) break;
		switch (*str++) {
			break; case '\2':  style.b ^= true;
			break; case '\17': style = Default;
			break; case '\26': style.r ^= true;
			break; case '\35': style.i ^= true;
			break; case '\37': style.u ^= true;
			break; case '\3': {
				if (!isdigit(*str)) {
					style.fg = Default.fg;
					style.bg = Default.bg;
					break;
				}
				style.fg = *str++ - '0';
				if (isdigit(*str)) style.fg = style.fg * 10 + *str++ - '0';
				if (str[0] != ',' || !isdigit(str[1])) break;
				str++;
				style.bg = *str++ - '0';
				if (isdigit(*str)) style.bg = style.bg * 10 + *str++ - '0';
			}
		}
	}
	return khtml_closeto(html, top) || khtml_closeelem(html, 1);
}

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

static enum kcgi_err
eventTime(struct khtmlreq *html, struct kreq *req, struct Event *event) {
	char *page = NULL;
	char *href = NULL;
	if (event->network && event->context && !req->fieldmap[Export]) {
		page = khttp_urlpart(
			NULL, NULL, Pages[Events],
			Keys[Network].name, event->network,
			Keys[Context].name, event->context,
			Keys[After].name, timestamp(event->time - eventsOverlap),
			NULL
		);
		if (!page) err(EX_OSERR, "khttp_urlpart");
	}
	asprintf(&href, "%s#%" PRId64, (page ? page : ""), event->event);
	if (!href) err(EX_OSERR, "asprintf");
	if (page) free(page);

	const char *stamp = timestamp(event->time);
	enum kcgi_err error = 0
		|| khtml_attr(html, KELEM_TD, KATTR_CLASS, "time", KATTR__MAX)
		|| khtml_attr(html, KELEM_A, KATTR_HREF, href, KATTR__MAX)
		|| khtml_attr(
			html, KELEM_TIME,
			KATTR_DATETIME, stamp,
			KATTR__MAX
		)
		|| khtml_puts(html, stamp)
		|| khtml_closeelem(html, 3);
	free(href);
	return error;
}

static enum kcgi_err
eventNetwork(struct khtmlreq *html, struct kreq *req, struct Event *event) {
	if (!req->fieldmap[Query] || req->fieldmap[Network]) return KCGI_OK;
	if (req->fieldmap[Export]) {
		return 0
			|| khtml_attr(html, KELEM_TD, KATTR_CLASS, "network", KATTR__MAX)
			|| khtml_puts(html, event->network)
			|| khtml_closeelem(html, 1);
	}
	char *href = khttp_urlpart(
		NULL, NULL, Pages[Search],
		Keys[Network].name, event->network,
		Keys[Query].name, req->fieldmap[Query]->parsed.s,
		NULL
	);
	if (!href) err(EX_OSERR, "khttp_urlpart");
	enum kcgi_err error = 0
		|| khtml_attr(html, KELEM_TD, KATTR_CLASS, "network", KATTR__MAX)
		|| khtml_attr(html, KELEM_A, KATTR_HREF, href, KATTR__MAX)
		|| khtml_puts(html, event->network)
		|| khtml_closeelem(html, 2);
	free(href);
	return error;
}

static enum kcgi_err
eventContext(struct khtmlreq *html, struct kreq *req, struct Event *event) {
	if (!req->fieldmap[Query] || req->fieldmap[Context]) return KCGI_OK;
	if (req->fieldmap[Export]) {
		return 0
			|| khtml_attr(html, KELEM_TD, KATTR_CLASS, "context", KATTR__MAX)
			|| khtml_puts(html, event->context)
			|| khtml_closeelem(html, 1);
	}
	char *href = khttp_urlpart(
		NULL, NULL, Pages[Search],
		Keys[Network].name, event->network,
		Keys[Context].name, event->context,
		Keys[Query].name, req->fieldmap[Query]->parsed.s,
		NULL
	);
	if (!href) err(EX_OSERR, "khttp_urlpart");
	enum kcgi_err error = 0
		|| khtml_attr(html, KELEM_TD, KATTR_CLASS, "context", KATTR__MAX)
		|| khtml_attr(html, KELEM_A, KATTR_HREF, href, KATTR__MAX)
		|| khtml_puts(html, event->context)
		|| khtml_closeelem(html, 2);
	free(href);
	return error;
}

static int hash(const char *str) {
	if (*str == '~') str++;
	uint32_t hash = 0;
	for (; *str; ++str) {
		hash = (hash << 5) | (hash >> 27);
		hash ^= *str;
		hash *= 0x27220A95;
	}
	return 2 + hash % 74;
}

static enum kcgi_err
eventNick(struct khtmlreq *html, const struct Event *event) {
	char *mask = NULL;
	char class[sizeof("fg99")];
	snprintf(
		class, sizeof(class), "fg%02d",
		hash(strcmp(event->user, "*") ? event->user : event->nick)
	);
	asprintf(
		&mask, "%s!%s@%s",
		event->nick, event->user, (htmlHideHost ? "*" : event->host)
	);
	if (!mask) err(EX_OSERR, "asprintf");
	const char *format = "%s";
	switch (event->type) {
		break; case Privmsg: format = "<%s>";
		break; case Notice:  format = "-%s-";
		break; case Action:  format = "* %s";
		break; default:;
	}
	enum kcgi_err error = 0
		|| khtml_attr(html, KELEM_TD, KATTR_CLASS, "nick", KATTR__MAX)
		|| khtml_attr(
			html, KELEM_SPAN,
			KATTR_CLASS, class,
			KATTR_TITLE, mask,
			KATTR__MAX
		)
		|| khtml_printf(html, format, event->nick)
		|| khtml_closeelem(html, 2);
	free(mask);
	return error;
}

static enum kcgi_err
maybeMessage(struct khtmlreq *html, const struct Event *event) {
	if (!event->message) return KCGI_OK;
	return 0
		|| khtml_puts(html, " (")
		|| htmlIRC(html, event->message)
		|| khtml_puts(html, ")");
}

static enum kcgi_err
eventMessage(struct khtmlreq *html, const struct Event *event) {
	enum kcgi_err error = khtml_attr(
		html, KELEM_TD,
		KATTR_CLASS, "message",
		KATTR__MAX
	);
	if (error) return error;
	switch (event->type) {
		break; case Join: {
			error = khtml_puts(html, "joined");
		}
		break; case Part: {
			error = khtml_puts(html, "left") || maybeMessage(html, event);
		}
		break; case Quit: {
			error = khtml_puts(html, "quit") || maybeMessage(html, event);
		}
		break; case Kick: {
			if (!event->target) break;
			error = 0
				|| khtml_printf(html, "kicked %s", event->target)
				|| maybeMessage(html, event);
		}
		break; case Nick: {
			if (!event->target) break;
			char class[sizeof("fg99")];
			snprintf(
				class, sizeof(class), "fg%02d",
				hash(strcmp(event->user, "*") ? event->user : event->target)
			);
			error = 0
				|| khtml_puts(html, "changed nick to ")
				|| khtml_attr(html, KELEM_SPAN, KATTR_CLASS, class, KATTR__MAX)
				|| khtml_puts(html, event->target)
				|| khtml_closeelem(html, 1);
		}
		break; case Topic: {
			if (!event->message) break;
			error = 0
				|| khtml_puts(html, "set the topic: ")
				|| htmlIRC(html, event->message);
		}
		break; case Ban: {
			if (!event->target) break;
			error = khtml_printf(html, "banned %s", event->target);
		}
		break; case Unban: {
			if (!event->target) break;
			error = khtml_printf(html, "unbanned %s", event->target);
		}
		break; default: {
			if (event->message) error = htmlIRC(html, event->message);
		}
	}
	return error || khtml_closeelem(html, 1);
}

static const char *Types[TypesLen] = {
#define X(id, name) [id] = name,
	ENUM_TYPE
#undef X
};

enum kcgi_err
htmlEvent(struct khtmlreq *html, struct kreq *req, struct Event *event) {
	const char *type = (event->type < TypesLen ? Types[event->type] : "unknown");
	return 0
		|| khtml_attrx(
			html, KELEM_TR,
			KATTR_ID, KATTRX_INT, event->event,
			KATTR_CLASS, KATTRX_STRING, type,
			KATTR__MAX
		)
		|| eventTime(html, req, event)
		|| eventNetwork(html, req, event)
		|| eventContext(html, req, event)
		|| eventNick(html, event)
		|| eventMessage(html, event)
		|| khtml_closeelem(html, 1);
}

static const char *SourceURL = "https://git.causal.agency/scooper";
static const char *SyntaxURL = {
	"https://www.sqlite.org/fts5.html#full_text_query_syntax"
};
static const char *Columns = {
	"network, channel, query, nick, user, target, message"
};

enum kcgi_err htmlFooter(struct khtmlreq *html, struct kreq *req) {
	if (req->fieldmap[Export]) return KCGI_OK;
	return 0
		|| khtml_closeto(html, 0)
		|| khtml_elem(html, KELEM_FOOTER)
		|| khtml_elem(html, KELEM_SPAN)
		|| khtml_attr(html, KELEM_A, KATTR_HREF, SourceURL, KATTR__MAX)
		|| khtml_puts(html, "scooper is AGPLv3+")
		|| khtml_closeelem(html, 2)
		|| khtml_putc(html, ' ')
		|| khtml_elem(html, KELEM_SPAN)
		|| khtml_attr(html, KELEM_A, KATTR_HREF, SyntaxURL, KATTR__MAX)
		|| khtml_puts(html, "Search syntax")
		|| khtml_closeelem(html, 1)
		|| khtml_putc(html, ' ')
		|| khtml_attr(html, KELEM_SPAN, KATTR_TITLE, Columns, KATTR__MAX)
		|| khtml_puts(html, "Columns")
		|| khtml_closeto(html, 0);
}