<?php
/* Icinga Web 2 | (c) 2014 Icinga Development Team | GPLv2+ */

namespace Icinga\Module\Monitoring\Forms\Config;

use Exception;
use InvalidArgumentException;
use Icinga\Application\Config;
use Icinga\Data\ConfigObject;
use Icinga\Data\ResourceFactory;
use Icinga\Exception\ConfigurationError;
use Icinga\Exception\IcingaException;
use Icinga\Exception\NotFoundError;
use Icinga\Forms\ConfigForm;
use Icinga\Web\Form;

/**
 * Form for managing monitoring backends
 */
class BackendConfigForm extends ConfigForm
{
    /**
     * The available monitoring backend resources split by type
     *
     * @var array
     */
    protected $resources;

    /**
     * The backend to load when displaying the form for the first time
     *
     * @var string
     */
    protected $backendToLoad;

    /**
     * Initialize this form
     */
    public function init()
    {
        $this->setName('form_config_monitoring_backends');
        $this->setSubmitLabel($this->translate('Save Changes'));
    }

    /**
     * Set the resource configuration to use
     *
     * @param   Config  $resourceConfig     The resource configuration
     *
     * @return  $this
     *
     * @throws  ConfigurationError          In case there are no valid monitoring backend resources
     */
    public function setResourceConfig(Config $resourceConfig)
    {
        $resources = array();
        foreach ($resourceConfig as $name => $resource) {
            if ($resource->type === 'db') {
                $resources['ido'][$name] = $name;
            }
        }

        if (empty($resources)) {
            throw new ConfigurationError($this->translate(
                'Could not find any valid monitoring backend resources. Please configure a database resource first.'
            ));
        }

        $this->resources = $resources;
        return $this;
    }

    /**
     * Populate the form with the given backend's config
     *
     * @param   string  $name
     *
     * @return  $this
     *
     * @throws  NotFoundError   In case no backend with the given name is found
     */
    public function load($name)
    {
        if (! $this->config->hasSection($name)) {
            throw new NotFoundError('No monitoring backend called "%s" found', $name);
        }

        $this->backendToLoad = $name;
        return $this;
    }

    /**
     * Add a new monitoring backend
     *
     * The backend to add is identified by the array-key `name'.
     *
     * @param   array   $data
     *
     * @return  $this
     *
     * @throws  InvalidArgumentException    In case $data does not contain a backend name
     * @throws  IcingaException             In case a backend with the same name already exists
     */
    public function add(array $data)
    {
        if (! isset($data['name'])) {
            throw new InvalidArgumentException('Key \'name\' missing');
        }

        $backendName = $data['name'];
        if ($this->config->hasSection($backendName)) {
            throw new IcingaException(
                $this->translate('A monitoring backend with the name "%s" does already exist'),
                $backendName
            );
        }

        unset($data['name']);
        $this->config->setSection($backendName, $data);
        return $this;
    }

    /**
     * Edit a monitoring backend
     *
     * @param   string  $name
     * @param   array   $data
     *
     * @return  $this
     *
     * @throws  NotFoundError   In case no backend with the given name is found
     */
    public function edit($name, array $data)
    {
        if (! $this->config->hasSection($name)) {
            throw new NotFoundError('No monitoring backend called "%s" found', $name);
        }

        $backendConfig = $this->config->getSection($name);
        if (isset($data['name'])) {
            if ($data['name'] !== $name) {
                $this->config->removeSection($name);
                $name = $data['name'];
            }

            unset($data['name']);
        }

        $backendConfig->merge($data);
        $this->config->setSection($name, $backendConfig);
        return $this;
    }

    /**
     * Remove a monitoring backend
     *
     * @param   string  $name
     *
     * @return  $this
     */
    public function delete($name)
    {
        $this->config->removeSection($name);
        return $this;
    }

    /**
     * Create and add elements to this form
     *
     * @param   array   $formData
     */
    public function createElements(array $formData)
    {
        $this->addElement(
            'checkbox',
            'disabled',
            array(
                'required'  => true,
                'label'     => $this->translate('Disable This Backend')
            )
        );
        $this->addElement(
            'text',
            'name',
            array(
                'required'      => true,
                'label'         => $this->translate('Backend Name'),
                'description'   => $this->translate(
                    'The name of this monitoring backend that is used to differentiate it from others'
                )
            )
        );

        $resourceType = isset($formData['type']) ? $formData['type'] : null;

        $resourceTypes = array();
        if ($resourceType === 'ido' || array_key_exists('ido', $this->resources)) {
            $resourceTypes['ido'] = 'IDO Backend';
        }

        if ($resourceType === null) {
            $resourceType = key($resourceTypes);
        }

        $this->addElement(
            'select',
            'type',
            array(
                'required'      => true,
                'autosubmit'    => true,
                'label'         => $this->translate('Backend Type'),
                'description'   => $this->translate(
                    'The type of data source used for retrieving monitoring information'
                ),
                'multiOptions'  => $resourceTypes
            )
        );

        $this->addElement(
            'select',
            'resource',
            array(
                'required'      => true,
                'label'         => $this->translate('Resource'),
                'description'   => $this->translate('The resource to use'),
                'multiOptions'  => $this->resources[$resourceType],
                'value'         => current($this->resources[$resourceType]),
                'autosubmit'    => true
            )
        );
        $resourceName = isset($formData['resource']) ? $formData['resource'] : $this->getValue('resource');
        $this->addElement(
            'note',
            'resource_note',
            array(
                'escape'        => false,
                'value'         => sprintf(
                    '<a href="%1$s" data-base-target="_next" title="%2$s" aria-label="%2$s">%3$s</a>',
                    $this->getView()->url('config/editresource', array('resource' => $resourceName)),
                    sprintf($this->translate('Show the configuration of the %s resource'), $resourceName),
                    $this->translate('Show resource configuration')
                )
            )
        );

        if (isset($formData['skip_validation']) && $formData['skip_validation']) {
            // In case another error occured and the checkbox was displayed before
            $this->addSkipValidationCheckbox();
        }
    }

    /**
     * Populate the configuration of the backend to load
     */
    public function onRequest()
    {
        if ($this->backendToLoad) {
            $data = $this->config->getSection($this->backendToLoad)->toArray();
            $data['name'] = $this->backendToLoad;
            $this->populate($data);
        }
    }

    /**
     * Return whether the given values are valid
     *
     * @param   array   $formData   The data to validate
     *
     * @return  bool
     */
    public function isValid($formData)
    {
        if (! parent::isValid($formData)) {
            return false;
        }

        if (($el = $this->getElement('skip_validation')) === null || false === $el->isChecked()) {
            $resourceConfig = ResourceFactory::getResourceConfig($this->getValue('resource'));
            if (! self::isValidIdoSchema($this, $resourceConfig) || !self::isValidIdoInstance($this, $resourceConfig)) {
                if ($el === null) {
                    $this->addSkipValidationCheckbox();
                }

                return false;
            }
        }

        return true;
    }

    /**
     * Add a checkbox to the form by which the user can skip the schema validation
     */
    protected function addSkipValidationCheckbox()
    {
        $this->addElement(
            'checkbox',
            'skip_validation',
            array(
                'order'         => 0,
                'ignore'        => true,
                'required'      => true,
                'label'         => $this->translate('Skip Validation'),
                'description'   => $this->translate(
                    'Check this to not to validate the IDO schema of the chosen resource.'
                )
            )
        );
    }

    /**
     * Return whether the given resource contains a valid IDO schema
     *
     * @param   Form            $form
     * @param   ConfigObject    $resourceConfig
     *
     * @return  bool
     */
    public static function isValidIdoSchema(Form $form, ConfigObject $resourceConfig)
    {
        try {
            $db = ResourceFactory::createResource($resourceConfig);
            $db->select()->from('icinga_dbversion', array('version'))->fetchOne();
        } catch (Exception $_) {
            $form->error($form->translate(
                'Cannot find the IDO schema. Please verify that the given database '
                . 'contains the schema and that the configured user has access to it.'
            ));
            return false;
        }

        return true;
    }

    /**
     * Return whether a single icinga instance is writing to the given resource
     *
     * @param   Form            $form
     * @param   ConfigObject    $resourceConfig
     *
     * @return  bool                                True if it's a single instance, false if none
     *                                              or multiple instances are writing to it
     */
    public static function isValidIdoInstance(Form $form, ConfigObject $resourceConfig)
    {
        $db = ResourceFactory::createResource($resourceConfig);
        $rowCount = $db->select()->from('icinga_instances')->count();

        if ($rowCount === 0) {
            $form->warning($form->translate(
                'There is currently no icinga instance writing to the IDO. Make sure '
                . 'that a icinga instance is configured and able to write to the IDO.'
            ));
            return false;
        } elseif ($rowCount > 1) {
            $form->warning($form->translate(
                'There is currently more than one icinga instance writing to the IDO. You\'ll see all objects from all'
                . ' instances without any differentation. If this is not desired, consider setting up a separate IDO'
                . ' for each instance.'
            ));
            return false;
        }

        return true;
    }
}
