<?php defined('BASEPATH') or exit('No direct script access allowed');

/* ----------------------------------------------------------------------------
 * Easy!Appointments - Open Source Web Scheduler
 *
 * @package     EasyAppointments
 * @author      A.Tselegidis <alextselegidis@gmail.com>
 * @copyright   Copyright (c) 2013 - 2020, Alex Tselegidis
 * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
 * @link        http://easyappointments.org
 * @since       v1.0.0
 * ---------------------------------------------------------------------------- */

/**
 * Admins Model Class
 *
 * Handles the database actions for admin users management.
 *
 * @property CI_DB_query_builder $db
 * @property CI_Loader $load
 *
 * @package Models
 */
class Admins_Model extends CI_Model {
    /**
     * Add (insert or update) an admin user record into database.
     *
     * @param array $admin Contains the admin user data.
     *
     * @return int Returns the record id.
     *
     * @throws Exception When the admin data are invalid (see validate() method).
     */
    public function add($admin)
    {
        $this->validate($admin);

        if ($this->exists($admin) && ! isset($admin['id']))
        {
            $admin['id'] = $this->find_record_id($admin);
        }

        if ( ! isset($admin['id']))
        {
            $admin['id'] = $this->insert($admin);
        }
        else
        {
            $admin['id'] = $this->update($admin);
        }

        return (int)$admin['id'];
    }

    /**
     * Validate admin user data before add() operation is executed.
     *
     * @param array $admin Contains the admin user data.
     *
     * @return bool Returns the validation result.
     *
     * @throws Exception When data are invalid.
     */
    public function validate($admin)
    {
        $this->load->helper('data_validation');

        // If a record id is provided then check whether the record exists in the database.
        if (isset($admin['id']))
        {
            $num_rows = $this->db->get_where('users', ['id' => $admin['id']])->num_rows();

            if ($num_rows === 0)
            {
                throw new Exception('Given admin id does not exist in database: ' . $admin['id']);
            }
        }

        // Validate required fields integrity.
        if ( ! isset($admin['last_name'])
            || ! isset($admin['email'])
            || ! isset($admin['phone_number']))
        {
            throw new Exception('Not all required fields are provided: ' . print_r($admin, TRUE));
        }

        // Validate admin email address.
        if ( ! filter_var($admin['email'], FILTER_VALIDATE_EMAIL))
        {
            throw new Exception('Invalid email address provided: ' . $admin['email']);
        }

        // Check if username exists.
        if (isset($admin['settings']['username']))
        {
            $user_id = (isset($admin['id'])) ? $admin['id'] : '';
            if ( ! $this->validate_username($admin['settings']['username'], $user_id))
            {
                throw new Exception ('Username already exists. Please select a different '
                    . 'username for this record.');
            }
        }

        // Validate admin password
        if (isset($admin['settings']['password']))
        {
            if (strlen($admin['settings']['password']) < MIN_PASSWORD_LENGTH)
            {
                throw new Exception('The user password must be at least '
                    . MIN_PASSWORD_LENGTH . ' characters long.');
            }
        }

        // Validate calendar view mode.
        if (isset($admin['settings']['calendar_view']) && ($admin['settings']['calendar_view'] !== CALENDAR_VIEW_DEFAULT
                && $admin['settings']['calendar_view'] !== CALENDAR_VIEW_TABLE))
        {
            throw new Exception('The calendar view setting must be either "' . CALENDAR_VIEW_DEFAULT
                . '" or "' . CALENDAR_VIEW_TABLE . '", given: ' . $admin['settings']['calendar_view']);
        }

        // When inserting a record the email address must be unique.
        $admin_id = (isset($admin['id'])) ? $admin['id'] : '';

        $num_rows = $this->db
            ->select('*')
            ->from('users')
            ->join('roles', 'roles.id = users.id_roles', 'inner')
            ->where('roles.slug', DB_SLUG_ADMIN)
            ->where('users.email', $admin['email'])
            ->where('users.id <>', $admin_id)
            ->get()
            ->num_rows();

        if ($num_rows > 0)
        {
            throw new Exception('Given email address belongs to another admin record. '
                . 'Please use a different email.');
        }

        return TRUE; // Operation completed successfully.
    }

    /**
     * Validate Records Username
     *
     * @param string $username The provider records username.
     * @param int $user_id The user record id.
     *
     * @return bool Returns the validation result.
     */
    public function validate_username($username, $user_id)
    {
        $num_rows = $this->db->get_where('user_settings',
            ['username' => $username, 'id_users <> ' => $user_id])->num_rows();
        return ($num_rows > 0) ? FALSE : TRUE;
    }

    /**
     * Check whether a particular admin record exists in the database.
     *
     * @param array $admin Contains the admin data. The 'email' value is required to be present at the moment.
     *
     * @return bool Returns whether the record exists or not.
     *
     * @throws Exception When the 'email' value is not present on the $admin argument.
     */
    public function exists($admin)
    {
        if ( ! isset($admin['email']))
        {
            throw new Exception('Admin email is not provided: ' . print_r($admin, TRUE));
        }

        // This method shouldn't depend on another method of this class.
        $num_rows = $this->db
            ->select('*')
            ->from('users')
            ->join('roles', 'roles.id = users.id_roles', 'inner')
            ->where('users.email', $admin['email'])
            ->where('roles.slug', DB_SLUG_ADMIN)
            ->get()->num_rows();

        return $num_rows > 0;
    }

    /**
     * Find the database record id of an admin user.
     *
     * @param array $admin Contains the admin data. The 'email' value is required in order to find the record id.
     *
     * @return int Returns the record id
     *
     * @throws Exception When the 'email' value is not present on the $admin array.
     */
    public function find_record_id($admin)
    {
        if ( ! isset($admin['email']))
        {
            throw new Exception('Admin email was not provided: ' . print_r($admin, TRUE));
        }

        $result = $this->db
            ->select('users.id')
            ->from('users')
            ->join('roles', 'roles.id = users.id_roles', 'inner')
            ->where('users.email', $admin['email'])
            ->where('roles.slug', DB_SLUG_ADMIN)
            ->get();

        if ($result->num_rows() == 0)
        {
            throw new Exception('Could not find admin record id.');
        }

        return (int)$result->row()->id;
    }

    /**
     * Insert a new admin record into the database.
     *
     * @param array $admin Contains the admin data.
     *
     * @return int Returns the new record id.
     *
     * @throws Exception When the insert operation fails.
     */
    protected function insert($admin)
    {
        $this->load->helper('general');

        $admin['id_roles'] = $this->get_admin_role_id();
        $settings = $admin['settings'];
        unset($admin['settings']);

        $this->db->trans_begin();

        if ( ! $this->db->insert('users', $admin))
        {
            throw new Exception('Could not insert admin into the database.');
        }

        $admin['id'] = (int)$this->db->insert_id();
        $settings['id_users'] = $admin['id'];
        $settings['salt'] = generate_salt();
        $settings['password'] = hash_password($settings['salt'], $settings['password']);

        // Insert admin settings.
        if ( ! $this->db->insert('user_settings', $settings))
        {
            $this->db->trans_rollback();
            throw new Exception('Could not insert admin settings into the database.');
        }

        $this->db->trans_complete();

        return $admin['id'];
    }

    /**
     * Get the admin users role id.
     *
     * @return int Returns the role record id.
     */
    public function get_admin_role_id()
    {
        return (int)$this->db->get_where('roles', ['slug' => DB_SLUG_ADMIN])->row()->id;
    }

    /**
     * Update an existing admin record in the database.
     *
     * @param array $admin Contains the admin record data.
     *
     * @return int Returns the record id.
     *
     * @throws Exception When the update operation fails.
     */
    protected function update($admin)
    {
        $this->load->helper('general');

        $settings = $admin['settings'];
        unset($admin['settings']);
        $settings['id_users'] = $admin['id'];

        if (isset($settings['password']))
        {
            $salt = $this->db->get_where('user_settings', ['id_users' => $admin['id']])->row()->salt;
            $settings['password'] = hash_password($salt, $settings['password']);
        }

        $this->db->where('id', $admin['id']);
        if ( ! $this->db->update('users', $admin))
        {
            throw new Exception('Could not update admin record.');
        }

        $this->db->where('id_users', $settings['id_users']);
        if ( ! $this->db->update('user_settings', $settings))
        {
            throw new Exception('Could not update admin settings.');
        }

        return (int)$admin['id'];
    }

    /**
     * Delete an existing admin record from the database.
     *
     * @param int $admin_id The admin record id to be deleted.
     *
     * @return bool Returns the delete operation result.
     *
     * @throws Exception When the $admin_id is not a valid int value.
     * @throws Exception When the record to be deleted is the only one admin user left on the system.
     */
    public function delete($admin_id)
    {
        if ( ! is_numeric($admin_id))
        {
            throw new Exception('Invalid argument type $admin_id: ' . $admin_id);
        }

        // There must be always at least one admin user. If this is the only admin
        // the system, it cannot be deleted.
        $admin_count = $this->db->get_where('users',
            ['id_roles' => $this->get_admin_role_id()])->num_rows();
        if ($admin_count == 1)
        {
            throw new Exception('Record could not be deleted. The system requires at least '
                . 'one admin user.');
        }

        $num_rows = $this->db->get_where('users', ['id' => $admin_id])->num_rows();
        if ($num_rows == 0)
        {
            return FALSE; // Record does not exist in database.
        }

        return $this->db->delete('users', ['id' => $admin_id]);
    }

    /**
     * Get a specific admin record from the database.
     *
     * @param int $admin_id The id of the record to be returned.
     *
     * @return array Returns an array with the admin user data.
     *
     * @throws Exception When the $admin_id is not a valid int value.
     */
    public function get_row($admin_id)
    {
        if ( ! is_numeric($admin_id))
        {
            throw new Exception('$admin_id argument is not a valid numeric value: ' . $admin_id);
        }

        // Check if record exists
        if ($this->db->get_where('users', ['id' => $admin_id])->num_rows() == 0)
        {
            throw new Exception('The given admin id does not match a record in the database.');
        }

        $admin = $this->db->get_where('users', ['id' => $admin_id])->row_array();

        $admin['settings'] = $this->db->get_where('user_settings',
            ['id_users' => $admin_id])->row_array();
        unset($admin['settings']['id_users']);


        return $admin;
    }

    /**
     * Get a specific field value from the database.
     *
     * @param string $field_name The field name of the value to be returned.
     * @param int $admin_id Record id of the value to be returned.
     *
     * @return string Returns the selected record value from the database.
     *
     * @throws Exception When the $field_name argument is not a valid string.
     * @throws Exception When the $admin_id is not a valid int.
     * @throws Exception When the admin record does not exist in the database.
     * @throws Exception When the selected field value is not present on database.
     */
    public function get_value($field_name, $admin_id)
    {
        if ( ! is_string($field_name))
        {
            throw new Exception('$field_name argument is not a string: ' . $field_name);
        }

        if ( ! is_numeric($admin_id))
        {
            throw new Exception('$admin_id argument is not a valid numeric value: ' . $admin_id);
        }

        // Check whether the admin record exists.
        $result = $this->db->get_where('users', ['id' => $admin_id]);
        if ($result->num_rows() == 0)
        {
            throw new Exception('The record with the given id does not exist in the '
                . 'database: ' . $admin_id);
        }

        // Check if the required field name exist in database.
        $provider = $result->row_array();
        if ( ! isset($provider[$field_name]))
        {
            throw new Exception('The given $field_name argument does not exist in the '
                . 'database: ' . $field_name);
        }

        return $provider[$field_name];
    }

    /**
     * Get all, or specific admin records from database.
     *
     * @param mixed|null $where (OPTIONAL) The WHERE clause of the query to be executed. Use this to get
     * specific admin records.
     * @param mixed|null $order_by
     * @param int|null $limit
     * @param int|null $offset
     * @return array Returns an array with admin records.
     */
    public function get_batch($where = NULL, $order_by = NULL, $limit = NULL, $offset = NULL)
    {
        $role_id = $this->get_admin_role_id();

        if ($where !== NULL)
        {
            $this->db->where($where);
        }

        if ($order_by !== NULL)
        {
            $this->db->order_by($order_by);
        }

        $batch = $this->db->get_where('users', ['id_roles' => $role_id], $limit, $offset)->result_array();

        // Get every admin settings.
        foreach ($batch as &$admin)
        {
            $admin['settings'] = $this->db->get_where('user_settings',
                ['id_users' => $admin['id']])->row_array();
            unset($admin['settings']['id_users']);
        }

        return $batch;
    }
}