<?php
class DBEngine {
	/** @var null|string */
	public $name = null;

	public function init(PDO $db) {}

	public function scoreql_to_sql(string $scoreql): string {
		return $scoreql;
	}

	public function create_table_sql(string $name, string $data): string {
		return 'CREATE TABLE '.$name.' ('.$data.')';
	}
}

class MySQL extends DBEngine {
	/** @var string */
	public $name = "mysql";

	public function init(PDO $db) {
		$db->exec("SET NAMES utf8;");
	}

	public function scoreql_to_sql(string $data): string {
		$data = str_replace("SCORE_AIPK", "INTEGER PRIMARY KEY auto_increment", $data);
		$data = str_replace("SCORE_INET", "VARCHAR(45)", $data);
		$data = str_replace("SCORE_BOOL_Y", "'Y'", $data);
		$data = str_replace("SCORE_BOOL_N", "'N'", $data);
		$data = str_replace("SCORE_BOOL", "ENUM('Y', 'N')", $data);
		$data = str_replace("SCORE_DATETIME", "DATETIME", $data);
		$data = str_replace("SCORE_NOW", "\"1970-01-01\"", $data);
		$data = str_replace("SCORE_STRNORM", "", $data);
		$data = str_replace("SCORE_ILIKE", "LIKE", $data);
		return $data;
	}

	public function create_table_sql(string $name, string $data): string {
		$data = $this->scoreql_to_sql($data);
		$ctes = "ENGINE=InnoDB DEFAULT CHARSET='utf8'";
		return 'CREATE TABLE '.$name.' ('.$data.') '.$ctes;
	}
}

class PostgreSQL extends DBEngine {
	/** @var string */
	public $name = "pgsql";

	public function init(PDO $db) {
		if(array_key_exists('REMOTE_ADDR', $_SERVER)) {
			$db->exec("SET application_name TO 'shimmie [{$_SERVER['REMOTE_ADDR']}]';");
		}
		else {
			$db->exec("SET application_name TO 'shimmie [local]';");
		}
		$db->exec("SET statement_timeout TO 10000;");
	}

	public function scoreql_to_sql(string $data): string {
		$data = str_replace("SCORE_AIPK", "SERIAL PRIMARY KEY", $data);
		$data = str_replace("SCORE_INET", "INET", $data);
		$data = str_replace("SCORE_BOOL_Y", "'t'", $data);
		$data = str_replace("SCORE_BOOL_N", "'f'", $data);
		$data = str_replace("SCORE_BOOL", "BOOL", $data);
		$data = str_replace("SCORE_DATETIME", "TIMESTAMP", $data);
		$data = str_replace("SCORE_NOW", "current_timestamp", $data);
		$data = str_replace("SCORE_STRNORM", "lower", $data);
		$data = str_replace("SCORE_ILIKE", "ILIKE", $data);
		return $data;
	}

	public function create_table_sql(string $name, string $data): string {
		$data = $this->scoreql_to_sql($data);
		return "CREATE TABLE $name ($data)";
	}
}

// shimmie functions for export to sqlite
function _unix_timestamp($date) { return strtotime($date); }
function _now() { return date("Y-m-d h:i:s"); }
function _floor($a) { return floor($a); }
function _log($a, $b=null) {
	if(is_null($b)) return log($a);
	else return log($a, $b);
}
function _isnull($a) { return is_null($a); }
function _md5($a) { return md5($a); }
function _concat($a, $b) { return $a . $b; }
function _lower($a) { return strtolower($a); }
function _rand() { return rand(); }
function _ln($n) { return log($n); }

class SQLite extends DBEngine {
	/** @var string  */
	public $name = "sqlite";

	public function init(PDO $db) {
		ini_set('sqlite.assoc_case', 0);
		$db->exec("PRAGMA foreign_keys = ON;");
		$db->sqliteCreateFunction('UNIX_TIMESTAMP', '_unix_timestamp', 1);
		$db->sqliteCreateFunction('now', '_now', 0);
		$db->sqliteCreateFunction('floor', '_floor', 1);
		$db->sqliteCreateFunction('log', '_log');
		$db->sqliteCreateFunction('isnull', '_isnull', 1);
		$db->sqliteCreateFunction('md5', '_md5', 1);
		$db->sqliteCreateFunction('concat', '_concat', 2);
		$db->sqliteCreateFunction('lower', '_lower', 1);
		$db->sqliteCreateFunction('rand', '_rand', 0);
		$db->sqliteCreateFunction('ln', '_ln', 1);
	}

	public function scoreql_to_sql(string $data): string {
		$data = str_replace("SCORE_AIPK", "INTEGER PRIMARY KEY", $data);
		$data = str_replace("SCORE_INET", "VARCHAR(45)", $data);
		$data = str_replace("SCORE_BOOL_Y", "'Y'", $data);
		$data = str_replace("SCORE_BOOL_N", "'N'", $data);
		$data = str_replace("SCORE_BOOL", "CHAR(1)", $data);
		$data = str_replace("SCORE_NOW", "\"1970-01-01\"", $data);
		$data = str_replace("SCORE_STRNORM", "lower", $data);
		$data = str_replace("SCORE_ILIKE", "LIKE", $data);
		return $data;
	}

	public function create_table_sql(string $name, string $data): string {
		$data = $this->scoreql_to_sql($data);
		$cols = array();
		$extras = "";
		foreach(explode(",", $data) as $bit) {
			$matches = array();
			if(preg_match("/(UNIQUE)? ?INDEX\s*\((.*)\)/", $bit, $matches)) {
				$uni = $matches[1];
				$col = $matches[2];
				$extras .= "CREATE $uni INDEX {$name}_{$col} ON {$name}({$col});";
			}
			else {
				$cols[] = $bit;
			}
		}
		$cols_redone = implode(", ", $cols);
		return "CREATE TABLE $name ($cols_redone); $extras";
	}
}