/* 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 <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sysexits.h>
#include <unistd.h>

#include <kcgi.h>
#include <sqlite3.h>

#define SQL(...) #__VA_ARGS__

enum { DatabaseVersion = 4 };

static sqlite3 *db;

static void dbClose(void) {
	// TODO: Finalize statements.
	sqlite3_close(db);
}

#define ENUM_PAGES \
	X(Networks, "networks") \
	X(Contexts, "contexts") \
	X(Events, "events") \
	X(Search, "search")

enum {
#define X(page, path) page,
	ENUM_PAGES
#undef X
	PagesLen,
};

static const char *Pages[PagesLen] = {
#define X(page, path) [page] = path,
	ENUM_PAGES
#undef X
};

#define ENUM_KEYS \
	X(Network, "network", kvalid_stringne) \
	X(Context, "context", kvalid_stringne) \
	X(After, "after", kvalid_stringne) \
	X(Query, "query", kvalid_stringne)

enum {
#define X(key, name, valid) key,
	ENUM_KEYS
#undef X
	KeysLen,
};

static const struct kvalid Keys[KeysLen] = {
#define X(key, name, valid) [key] = { valid, name },
	ENUM_KEYS
#undef X
};

static enum kcgi_err fail(struct kreq *req, enum khttp status) {
	return khttp_head(req, kresps[KRESP_STATUS], "%s", khttps[status])
		|| khttp_head(
			req, kresps[KRESP_CONTENT_TYPE], "%s", kmimetypes[KMIME_TEXT_PLAIN]
		)
		|| khttp_body(req)
		|| khttp_puts(req, khttps[status])
		|| khttp_putc(req, '\n');
}

static enum kcgi_err request(struct kreq *req) {
	if (req->method != KMETHOD_HEAD && req->method != KMETHOD_GET) {
		return fail(req, KHTTP_405);
	}
	if (req->mime != KMIME_TEXT_HTML || req->page == PagesLen) {
		return fail(req, KHTTP_404);
	}

	return KCGI_OK;
}

int main(int argc, char *argv[]) {
	bool fastCGI = false;
	bool public = false;
	const char *stylesheet = NULL;

	for (int opt; 0 < (opt = getopt(argc, argv, "fps:"));) {
		switch (opt) {
			break; case 'f': fastCGI = true;
			break; case 'p': public = true;
			break; case 's': stylesheet = optarg;
			break; default:  return EX_USAGE;
		}
	}
	if (optind == argc) errx(EX_USAGE, "database path required");

	int error = sqlite3_open_v2(argv[optind], &db, SQLITE_OPEN_READONLY, NULL);
	if (error) errx(EX_NOINPUT, "%s: %s", argv[optind], sqlite3_errmsg(db));
	atexit(dbClose);

	sqlite3_stmt *stmt;
	error = sqlite3_prepare_v2(
		db, SQL(PRAGMA user_version;), -1, &stmt, NULL
	);
	if (error) errx(EX_SOFTWARE, "%s", sqlite3_errmsg(db));

	error = sqlite3_step(stmt);
	if (error != SQLITE_ROW) errx(EX_SOFTWARE, "%s", sqlite3_errmsg(db));

	int version = sqlite3_column_int(stmt, 0);
	if (version != DatabaseVersion) {
		errx(EX_DATAERR, "unsupported database version %d", version);
	}
	sqlite3_finalize(stmt);

	// TODO: Prepare all statements with persist flag.
	
	if (fastCGI) {
		struct kfcgi *fcgi;
		enum kcgi_err error = khttp_fcgi_init(
			&fcgi, Keys, KeysLen, Pages, PagesLen, Networks
		);
		if (error) errx(EX_CONFIG, "khttp_fcgi_init: %s", kcgi_strerror(error));
		for (
			struct kreq req;
			KCGI_OK == (error = khttp_fcgi_parse(fcgi, &req));
			khttp_free(&req)
		) {
			error = request(&req);
			if (error && error != KCGI_HUP) break;
		}
		errx(EX_PROTOCOL, "khttp_fcgi_parse: %s", kcgi_strerror(error));
	} else {
		struct kreq req;
		enum kcgi_err error = khttp_parse(
			&req, Keys, KeysLen, Pages, PagesLen, Networks
		);
		if (error) errx(EX_PROTOCOL, "khttp_parse: %s", kcgi_strerror(error));
		error = request(&req);
		if (error) errx(EX_PROTOCOL, "%s", kcgi_strerror(error));
		khttp_free(&req);
	}
}