<?php
include_once './includes/Database.php';

const USER_LEVEL_MODERATOR = 'moderator';

function generate_invite_code(): string
{
	$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
	$result = '';

	for ($i = 0; $i < 8; $i++) {
		$result .= $characters[rand(0, strlen($characters) - 1)];
	}

	return $result;
}

class User
{
	public $id;
	public $name;
	public $password;
	public $date_registered;
	public $level = 'user';
	public $invite_code;
	public $generation;

	private $has_value = false;

	// Can't use a constructor here because we have two possible ways to get the user from the database
	// and PHP does not allow function overloading.
	public function get_by_id($id)
	{
		$sql = "SELECT user_name, user_password, user_date_registered, user_level, user_invite_code, user_generation FROM users WHERE user_id = ?;";
		$result = Database::get()->query($sql, "i", $id);

		if (empty($result)) {
			return;
		}

		$this->id = $id;
		$this->name = $result[0]['user_name'];
		$this->password = $result[0]['user_password'];
		$this->date_registered = $result[0]['user_date_registered'];
		$this->level = $result[0]['user_level'];
		$this->invite_code = $result[0]['user_invite_code'];
		$this->generation = $result[0]['user_generation'];

		$this->has_value = true;
	}

	// TODO: Duplicated code, there should be a common database read function for all models
	public function get_by_name($name)
	{
		$sql = "SELECT user_id, user_password, user_date_registered, user_level, user_invite_code, user_generation FROM users WHERE user_name = ?;";
		$result = Database::get()->query($sql, "s", $name);

		if (empty($result)) {
			return;
		}

		$this->id = $result[0]['user_id'];
		$this->name = $name;
		$this->password = $result[0]['user_password'];
		$this->date_registered = $result[0]['user_date_registered'];
		$this->level = $result[0]['user_level'];
		$this->invite_code = $result[0]['user_invite_code'];
		$this->generation = $result[0]['user_generation'];

		$this->has_value = true;
	}

	public function get_by_invite_code($invite_code)
	{
		$sql = "SELECT user_id, user_name, user_password, user_date_registered, user_level, user_generation FROM users WHERE user_invite_code = ?;";
		$result = Database::get()->query($sql, "s", $invite_code);

		if (empty($result)) {
			return;
		}

		$this->id = $result[0]['user_id'];
		$this->name = $result[0]['user_name'];
		$this->password = $result[0]['user_password'];
		$this->date_registered = $result[0]['user_date_registered'];
		$this->level = $result[0]['user_level'];
		$this->invite_code = $invite_code;
		$this->generation = $result[0]['user_generation'];

		$this->has_value = true;
	}

	public function has_value(): bool
    {
		return $this->has_value;
	}

	public static function register(string $username, string $password, int $generation)
	{
		$sql = "INSERT INTO users(user_name, user_password, user_date_registered, user_invite_code, user_generation) VALUES(?, ?, NOW(), ?, ?);";
		$pass_hash = password_hash($password, PASSWORD_DEFAULT);
		$invite_code = generate_invite_code();
		Database::get()->query($sql, "sssi", $username, $pass_hash, $invite_code, $generation);
	}

	public function update_invite_code()
	{
		$sql = "UPDATE users SET user_invite_code = ? WHERE user_id = ?";
		Database::get()->query($sql, "si", generate_invite_code(), $this->id);
	}

	public function change_password(string $pass_hash)
	{
		if (!Session::get()->is_signed_in()) {
			trigger_error('You are not signed in.');
			return;
		}

		if (Session::get()->get_current_user()->id != $this->id) {
			trigger_error("You can't change another user's password.");
			return;
		}

		$sql = "UPDATE users SET user_password = ? WHERE user_id = ?;";
		Database::get()->query($sql, "si", $pass_hash, $this->id);
	}

	public function get_threads(): array
	{
		$sql = "SELECT thread_id FROM threads WHERE thread_author = ? ORDER BY thread_last_post_date DESC";
		$result = Database::get()->query($sql, "i", $this->id);
		$threads = array();

		foreach ($result as $row) {
			$thread = new Thread($row['thread_id']);
			if ($thread->has_value())
				array_push($threads, $thread);
		}

		return $threads;
	}

	public static function username_exists(string $username): bool
	{
		$sql = "SELECT * FROM users WHERE user_name = ?;";
		$result = Database::get()->query($sql, "s", $username);

		return !empty($result);
	}

	public static function invite_code_exists($invite_code): bool
	{
		$sql = "SELECT * FROM users WHERE user_invite_code = ?;";
		$result = Database::get()->query($sql, "s", $invite_code);

		return !empty($result);
	}
}