<?php

/**
 * Basic object to load a mysql table inside an object.
 */
abstract class Table
{
	public const TYPE_STRING = 1;
	public const TYPE_INTEGER = 2;
	public const TYPE_FLOAT = 3;
	public const TYPE_DATETIME = 4;
	public const TYPE_BOOL = 5;

	protected const VALUE = 'value';
	protected const TYPE = 'type';

	protected ?DatabaseInterface $database;
	protected string $tableName;
	protected array $fields;
	protected string $primaryKey;
    protected bool $isPrimKeyManual = false;

	public function __construct(string $tableName, $id, ?DatabaseInterface & $database)
	{
		$this->tableName = $tableName;
		$this->fields = [];

        $this->database = $database;

        $this->database->Query(sprintf('DESCRIBE %s', $tableName));

        $result = $this->database->getResult();

		foreach ($result as $field) {
            $sqlType = substr_count(
                $field['Type'], '(') === 0 ? $field['Type'] : strstr($field['Type'],
                '(',
                true
            );

			switch ($sqlType) {
				case 'varchar':
				case 'char':
				case 'text':
				case 'longtext':
				case 'mediumtext':
				case 'tinytext':
					$type = self::TYPE_STRING;
					break;
				case 'int':
				case 'smallint':
				case 'mediumint':
				case 'bigint':
					$type = self::TYPE_INTEGER;
					break;
				case 'float':
				case 'decimal':
				case 'double':
				case 'real':
					$type = self::TYPE_FLOAT;
					break;
				case 'datetime':
                case 'date':
					$type = self::TYPE_DATETIME;
					break;
                case 'tinyint':
                    $type = self::TYPE_BOOL;
                    break;
				default:
					throw new Exception(sprintf('Type %s of field %s couldn\'t be handled', $sqlType, $field['Field']));
			}

            $this->addField($field['Field'], $type);

            if ($field['Key'] === 'PRI') {
				$this->primaryKey = $field['Field'];
			}
		}

		if (!$this->isPrimKeyManual && $id !== null) {
    		$this->loadById($id);
        }
    }

    public function getPrimaryKey()
    {
        if ($this->primaryKey === null) {
            return null;
        }

        return $this->getField($this->primaryKey);
    }

	protected function addField(string $name, int $type): void
	{
		if (!self::IsValidType($type)) {
			throw new Exception(
			    sprintf('Field %s has invalid type of %s!', $name, $type)
            );
		}

		$this->fields[$name] = [self::VALUE => null, self::TYPE => $type];
	}

    protected function loadById($id): void
	{
        try {
            $this->database->Query(
                sprintf('SELECT * FROM %s WHERE %s = :id', $this->tableName, $this->primaryKey),
                ['id' => $id]
            );
        } catch (Throwable $e) {
            throw new Exception();
        }

		$result = $this->database->getResult();

		if (count($result) === 0) {
			throw new Exception('No table entry with id ' . $id . ' found!');
		}

		foreach ($result[0] as $field => $value) {
			$this->setField($field, $value);
		}
	}

	public function Flush(): void
    {
        $this->database->Delete($this->tableName, []);
    }

    public function Delete(): void
    {
        try {
            $this->database->Delete($this->tableName, [$this->primaryKey => $this->getPrimaryKey()]);
        } catch (Throwable $e) {
            throw new Exception();
        }

        foreach ($this->GetAllFieldNames() as $field) {
            $this->fields[$field][self::VALUE] = null;
        }
    }

	protected function getField(string $name)
	{
		if (!array_key_exists($name, $this->fields)) {
			return null;
		}

		return $this->fields[$name][self::VALUE];
	}

    /**
     * Sets the value for the given field inside the database.
     */
	protected function setField(string $name, $value): void
	{
		if (!$this->HasField($name)) {
			throw new Exception(sprintf('Field %s doesn\'t exist!', $name));
		}

		if ($value === null) {
			$this->fields[$name][self::VALUE] = null;
			return;
		}

		switch ($this->fields[$name][self::TYPE]) {
			case self::TYPE_STRING:
				$this->fields[$name][self::VALUE] = (string)$value;
				return;
			case self::TYPE_INTEGER:
				$this->fields[$name][self::VALUE] = (int)$value;
				return;
			case self::TYPE_FLOAT:
				$this->fields[$name][self::VALUE] = (float)$value;
				return;
			case self::TYPE_DATETIME:
				try {
				    $this->fields[$name][self::VALUE] = new DateTime((string)$value);
                } catch (Exception $e) {
                    throw new Exception();
                }
				return;
            case self::TYPE_BOOL:
                $this->fields[$name][self::VALUE] = (bool)$value;
		}
	}

	/**
     * Checks if the table has the given column.
	 */
	public function HasField(string $name): bool
	{
		return array_key_exists($name, $this->fields);
	}

    /**
     * Saves the whole object into the database.
     */
	public function Save(): void
	{
		$fields = [];

		foreach ($this->GetAllFieldNames() as $fieldName) {
            $field = $this->getField($fieldName);

            if ($field instanceof DateTime) {
			    $fields[$fieldName] = $field->format('Y-m-d H:i:s');
            } else if (is_bool($field)) {
                $fields[$fieldName] = (int)$field;
            } else {
			    $fields[$fieldName] = $field;
            }
		}

		if ($this->isPrimKeyManual) {
            $this->saveWithManualId($fields);
        } else {
	        $this->saveWithPrimaryKey($fields);
        }
	}

	/**
	 * @return string[]
	 */
	public function GetAllFieldNames(): array
	{
		$fieldNames = [];

		foreach ($this->fields as $name => $field) {
			$fieldNames[] = $name;
		}

		return $fieldNames;
	}

    /**
     * Checks if the index is a valid backend type.
     */
	public static function IsValidType(int $type): bool
	{
		$validTypes = [
			self::TYPE_STRING,
			self::TYPE_INTEGER,
			self::TYPE_FLOAT,
			self::TYPE_DATETIME,
            self::TYPE_BOOL,
		];

		return in_array($type, $validTypes);
	}

	protected function saveWithManualId(array $fields): void
    {
        if ($this->getField($this->primaryKey) === null) {
            throw new Exception('Manual primary key must not be null!');
        }

        $hasKey = (bool)$this->database->Count(
            $this->tableName,
            [$this->primaryKey => $this->getField($this->primaryKey)]
        );

        if ($hasKey) {
            $this->database->Update(
                $this->tableName, $fields, [$this->primaryKey => $this->getField($this->primaryKey)]
            );
        } else {
            $this->database->Insert($this->tableName, $fields);
        }
    }

    protected function saveWithPrimaryKey(array $fields): void
    {
        if ($this->getField($this->primaryKey) !== null) {
            $this->database->Update(
                $this->tableName, $fields, [$this->primaryKey => $this->getField($this->primaryKey)]
            );
        } else {
            $this->setField($this->primaryKey, $this->database->Insert($this->tableName, $fields));
        }
    }
}