/* Copyright (C) 2019  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 <assert.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <sqlite3.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sysexits.h>

#define DATABASE_PATH "litterbox/litterbox.sqlite"

#define SQL(...) #__VA_ARGS__

enum { DatabaseVersion = 0 };

enum Type {
	Privmsg,
	Action,
	Notice,
	Join,
	Part,
	Kick,
	Quit,
	Nick,
	Topic,
};

static inline sqlite3 *dbOpen(char *path, int flags) {
	char *base = strrchr(path, '/');
	if (flags & SQLITE_OPEN_CREATE && base) {
		*base = '\0';
		int error = mkdir(path, 0700);
		if (error && errno != EEXIST) err(EX_CANTCREAT, "%s", path);
		*base = '/';
	}

	sqlite3 *db;
	int error = sqlite3_open_v2(path, &db, flags, NULL);
	if (error == SQLITE_CANTOPEN) {
		sqlite3_close(db);
		return NULL;
	}
	if (error) errx(EX_NOINPUT, "%s: %s", path, sqlite3_errmsg(db));

	sqlite3_busy_timeout(db, 1000);

	error = sqlite3_exec(db, SQL(PRAGMA foreign_keys = true;), NULL, NULL, NULL);
	if (error) errx(EX_SOFTWARE, "sqlite3_exec: %s", sqlite3_errmsg(db));

	return db;
}

static inline sqlite3 *dbFind(int flags) {
	const char *home = getenv("HOME");
	const char *dataHome = getenv("XDG_DATA_HOME");
	const char *dataDirs = getenv("XDG_DATA_DIRS");

	char path[PATH_MAX];
	if (dataHome) {
		snprintf(path, sizeof(path), "%s/" DATABASE_PATH, dataHome);
	} else {
		if (!home) errx(EX_CONFIG, "HOME unset");
		snprintf(path, sizeof(path), "%s/.local/share/" DATABASE_PATH, home);
	}
	sqlite3 *db = dbOpen(path, flags);
	if (db) return db;

	if (!dataDirs) dataDirs = "/usr/local/share:/usr/share";
	while (*dataDirs) {
		size_t len = strcspn(dataDirs, ":");
		snprintf(path, sizeof(path), "%.*s/" DATABASE_PATH, (int)len, dataDirs);
		db = dbOpen(path, flags);
		if (db) return db;
		dataDirs += len;
		if (*dataDirs) dataDirs++;
	}
	return NULL;
}

static inline void dbBegin(sqlite3 *db) {
	int error = sqlite3_exec(db, SQL(BEGIN TRANSACTION;), NULL, NULL, NULL);
	if (error) errx(EX_SOFTWARE, "sqlite3_exec: %s", sqlite3_errmsg(db));
}

static inline void dbCommit(sqlite3 *db) {
	int error = sqlite3_exec(db, SQL(COMMIT TRANSACTION;), NULL, NULL, NULL);
	if (error) errx(EX_SOFTWARE, "sqlite3_exec: %s", sqlite3_errmsg(db));
}

static inline sqlite3_stmt *
dbPrepare(sqlite3 *db, unsigned flags, const char *sql) {
	sqlite3_stmt *stmt;
	int error = sqlite3_prepare_v3(db, sql, -1, flags, &stmt, NULL);
	if (error) errx(EX_SOFTWARE, "sqlite3_prepare_v3: %s", sqlite3_errmsg(db));
	return stmt;
}

static inline void
dbBindText(sqlite3_stmt *stmt, int param, const char *text, int len) {
	int error = sqlite3_bind_text(stmt, param, text, len, NULL);
	if (!error) return;
	errx(
		EX_SOFTWARE, "sqlite3_bind_text: %s",
		sqlite3_errmsg(sqlite3_db_handle(stmt))
	);
}

static inline void dbBindInt(sqlite3_stmt *stmt, int param, int64_t value) {
	int error = sqlite3_bind_int64(stmt, param, value);
	if (!error) return;
	errx(
		EX_SOFTWARE, "sqlite3_bind_int64: %s",
		sqlite3_errmsg(sqlite3_db_handle(stmt))
	);
}

static inline int dbStep(sqlite3_stmt *stmt) {
	int error = sqlite3_step(stmt);
	if (error == SQLITE_ROW || error == SQLITE_DONE) return error;
	errx(
		EX_SOFTWARE, "sqlite3_step: %s",
		sqlite3_errmsg(sqlite3_db_handle(stmt))
	);
}

static inline int dbVersion(sqlite3 *db) {
	sqlite3_stmt *stmt = dbPrepare(db, 0, SQL(PRAGMA user_version;));
	assert(SQLITE_ROW == dbStep(stmt));
	int version = sqlite3_column_int(stmt, 0);
	sqlite3_finalize(stmt);
	return version;
}

static const char *InitSQL = SQL(
	BEGIN TRANSACTION;
	CREATE TABLE contexts (
		context INTEGER PRIMARY KEY,
		network TEXT NOT NULL,
		name TEXT NOT NULL,
		query BOOLEAN NOT NULL,
		UNIQUE (network, name)
	);
	CREATE TABLE names (
		name INTEGER PRIMARY KEY,
		nick TEXT NOT NULL,
		user TEXT NOT NULL,
		host TEXT NOT NULL,
		UNIQUE (nick, user, host)
	);
	CREATE TABLE events (
		event INTEGER PRIMARY KEY,
		time DATETIME NOT NULL,
		type INTEGER NOT NULL,
		context INTEGER NOT NULL REFERENCES contexts,
		name INTEGER NOT NULL REFERENCES names,
		target TEXT,
		message TEXT
	);
	CREATE VIRTUAL TABLE search USING fts5 (
		message,
		content = events,
		content_rowid = event,
		tokenize = 'porter'
	);
	CREATE TRIGGER eventsInsert AFTER INSERT ON events BEGIN
		INSERT INTO search (rowid, message) VALUES (new.event, new.message);
	END;
	CREATE TRIGGER eventsDelete AFTER DELETE ON events BEGIN
		INSERT INTO search (search, rowid, message)
		VALUES ('delete', old.event, old.message);
	END;
	COMMIT TRANSACTION;
);

static inline void dbInit(sqlite3 *db) {
	int error = sqlite3_exec(db, InitSQL, NULL, NULL, NULL);
	if (error) errx(EX_SOFTWARE, "sqlite3_exec: %s", sqlite3_errmsg(db));
}

static const char *MigrationSQL[] = {
	NULL,
};

static inline void dbMigrate(sqlite3 *db) {
	for (int version = dbVersion(db); version < DatabaseVersion; ++version) {
		int error = sqlite3_exec(db, MigrationSQL[version], NULL, NULL, NULL);
		if (error) errx(EX_SOFTWARE, "sqlite3_exec: %s", sqlite3_errmsg(db));
	}
}