<?php
class ModelNotFoundException extends Exception {}
class ModelCreateFailedException extends Exception {}
class ModelIllegalAccessException extends Exception {}
class ModelSetFailedException extends Exception {}

abstract class Model {
	public static
		$table             = '',
		$primary_key       = 'id',
		$protected_columns = ['id'],
		$fillable_columns  = [],
		$timestamps        = [],
		$dates             = [],
		$booleans          = [];

	protected $pdo, $data;

	const TABLE_PREFIX = '';

	public function __construct($pdo, $id) {
		$this->pdo = $pdo;

		$stmt = $this->pdo->prepare("SELECT * FROM `".self::table()."` WHERE `".static::$primary_key."`=?");
		$stmt->execute([$id]);
		if ($stmt->rowCount() == 0) {
			throw new ModelNotFoundException("The ".static::$table." with id '$id' could not be found.");
		}
		$this->data = $stmt->fetch(PDO::FETCH_ASSOC);
	}

	public function __set($key, $value) {
		if (!in_array($key, static::$fillable_columns)) {
			throw new ModelIllegalAccessException("Column `".self::table()."`.`$key` cannot be edited.");
		}
		if ($this->data[$key] == $value) {
			return;
		}
		$stmt = $this->pdo->prepare("UPDATE `".self::table()."` SET `$key`=? WHERE `".static::$primary_key."`=?");
		$stmt->execute([
			$this->mutator($key, $value),
			$this->data[static::$primary_key]
		]);
		if ($stmt->rowCount() != 1) {
			throw new ModelSetFailedException("Failed to update `".self::table()."`.`$key` to '$value'.");
		}
		$this->data[$key] = $value;
	}

	public function __get($key) {
		return $this->accessor($key, $this->data[$key]);
	}

	public static function create($pdo, $values) {
		$class = get_called_class();

		$columns = array_combine(static::$fillable_columns, $values);
		$questions = [];

		foreach ($columns as $column => $value) {
			$columns[$column] = $class::mutator($column, $value);
			$questions[] = '?';
		}

		$stmt = $pdo->prepare(
			"INSERT INTO `".self::table()."` " .
			"(`" . implode('`, `', array_keys($columns)) . "`) " .
			"VALUES (" . implode(',', $questions) . ")");
		$stmt->execute(array_values($columns));

		if ($stmt->rowCount() != 1)
			throw new ModelCreateFailedException();
		
		return new $class($pdo, $pdo->lastInsertId());
	}

	public static function searchIds($pdo, $where = [], $values = []) {
		$stmt = $pdo->prepare("SELECT `id` FROM `".static::table()."`" . ((count($where) > 0) ? (" WHERE (" . implode(') AND (', $where) . ")") : ""));
		$stmt->execute($values);

		$ids = [];
		foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $row) {
			$ids[] = $row['id'];
		}
		return $ids;
	}

	public static function search($pdo, $where = [], $values = []) {
		$class = get_called_class();

		$items = [];
		foreach (self::searchIds($pdo, $where, $values) as $id) {
			$items[] = new $class($pdo, $id);
		}
		return $items;
	}

	public static function count($pdo, $where = [], $values = []) {
		$class = get_called_class();

		$stmt = $pdo->prepare("SELECT COUNT(*) FROM `".static::table()."`" . ((count($where) > 0) ? (" WHERE (" . implode(') AND (', $where) . ")") : ""));
		$stmt->execute($values);

		return $stmt->fetchColumn();
	}

	protected static function accessor($key, $value) {
		if (is_null($value)) {
			return null;
		} elseif (in_array($key, static::$booleans)) {
			return (bool) $value;
		} elseif (in_array($key, static::$dates) || in_array($key, static::$timestamps)) {
			return strtotime($value);
		} else {
			return $value;
		}
	}

	protected static function mutator($key, $value) {
		if (in_array($key, static::$dates) && is_int($value)) {
			return date('Y-m-d', $value);
		} elseif (in_array($key, static::$timestamps) && is_int($value)) {
			return date('Y-m-d H:i:s', $value);
		} else {
			return (string) $value;
		}
	}

	public function delete() {
		$stmt = $this->pdo->prepare("DELETE FROM `".self::table()."` WHERE `".static::$primary_key."`=?");
		$stmt->execute([$this->data[static::$primary_key]]);
		return $stmt->rowCount() != 0;
	}

	private static function table() {
		return self::TABLE_PREFIX . static::$table;
	}
}