<?php

namespace SilverStripe\Admin;

use SilverStripe\Control\Controller;
use SilverStripe\Control\HTTPResponse;
use SilverStripe\Control\HTTPRequest;
use SilverStripe\Core\Convert;
use SilverStripe\Forms\HiddenField;
use SilverStripe\Forms\FormAction;
use SilverStripe\Forms\FieldList;
use SilverStripe\Forms\Form;
use SilverStripe\Forms\RequiredFields;
use SilverStripe\ORM\SS_List;
use SilverStripe\ORM\ValidationResult;
use SilverStripe\ORM\Versioning\ChangeSet;
use SilverStripe\ORM\Versioning\ChangeSetItem;
use SilverStripe\ORM\DataObject;
use SilverStripe\ORM\UnexpectedDataException;
use SilverStripe\Security\SecurityToken;
use SilverStripe\Security\PermissionProvider;
use LogicException;

/**
 * Campaign section of the CMS
 */
class CampaignAdmin extends LeftAndMain implements PermissionProvider {

	private static $allowed_actions = [
		'set',
		'sets',
		'schema',
		'DetailEditForm',
		'readCampaigns',
		'readCampaign',
		'deleteCampaign',
		'publishCampaign',
	];

	private static $menu_priority = 3;

	private static $menu_title = 'Campaigns';

	private static $tree_class = 'SilverStripe\\ORM\\Versioning\\ChangeSet';

	private static $url_handlers = [
		'GET sets' => 'readCampaigns',
		'POST set/$ID/publish' => 'publishCampaign',
		'GET set/$ID/$Name' => 'readCampaign',
		'DELETE set/$ID' => 'deleteCampaign',
	];

	private static $url_segment = 'campaigns';

	/**
	 * Size of thumbnail width
	 *
	 * @config
	 * @var int
	 */
	private static $thumbnail_width = 64;

	/**
	 * Size of thumbnail height
	 *
	 * @config
	 * @var int
	 */
	private static $thumbnail_height = 64;

	private static $required_permission_codes = 'CMS_ACCESS_CampaignAdmin';

	public function getClientConfig() {
		return array_merge(parent::getClientConfig(), [
			'reactRouter' => true,
			'form' => [
				// TODO Use schemaUrl instead
				'EditForm' => [
					'schemaUrl' => $this->Link('schema/EditForm')
				],
				'DetailEditForm' => [
					'schemaUrl' => $this->Link('schema/DetailEditForm')
				],
			],
			'itemListViewEndpoint' => [
				'url' => $this->Link() . 'set/:id/show',
				'method' => 'get'
			],
			'publishEndpoint' => [
				'url' => $this->Link() . 'set/:id/publish',
				'method' => 'post'
			],
			'treeClass' => $this->config()->tree_class
		]);
	}

	public function getEditForm($id = null, $fields = null)
    {
        $fields = new FieldList(
            CampaignAdminList::create('ChangeSets')
        );
        $actions = new FieldList();
        $form = Form::create($this, 'EditForm', $fields, $actions);

        // Set callback response
        $form->setValidationResponseCallback(function() use ($form) {
            $schemaId = $this->Link('schema/EditForm');
            return $this->getSchemaResponse($form, $schemaId);
        });

        return $form;
    }

    public function EditForm($request = null)
    {
        // Get ID either from posted back value, or url parameter
        $request = $request ?: $this->getRequest();
        $id = $request->param('ID') ?: $request->postVar('ID');
        return $this->getEditForm($id);
    }

    /**
	 * REST endpoint to get a list of campaigns.
	 *
	 * @return HTTPResponse
	 */
	public function readCampaigns() {
		$response = new HTTPResponse();
		$response->addHeader('Content-Type', 'application/json');
		$hal = $this->getListResource();
		$response->setBody(Convert::array2json($hal));
		return $response;
	}

	/**
	 * Get list contained as a hal wrapper
	 *
	 * @return array
	 */
	protected function getListResource() {
		$items = $this->getListItems();
		$count = $items->count();
		/** @var string $treeClass */
		$treeClass = $this->config()->tree_class;
		$hal = [
			'count' => $count,
			'total' => $count,
			'_links' => [
				'self' => [
					'href' => $this->Link('items')
				]
			],
			'_embedded' => [$treeClass => []]
		];
		foreach($items as $item) {
			/** @var ChangeSet $item */
			$resource = $this->getChangeSetResource($item);
			$hal['_embedded'][$treeClass][] = $resource;
		}
		return $hal;
	}

	/**
	 * Build item resource from a changeset
	 *
	 * @param ChangeSet $changeSet
	 * @return array
	 */
	protected function getChangeSetResource(ChangeSet $changeSet) {
		$hal = [
			'_links' => [
				'self' => [
					'href' => $this->SetLink($changeSet->ID)
				]
			],
			'ID' => $changeSet->ID,
			'Name' => $changeSet->Name,
			'Created' => $changeSet->Created,
			'LastEdited' => $changeSet->LastEdited,
			'State' => $changeSet->State,
			'IsInferred' => $changeSet->IsInferred,
			'canEdit' => $changeSet->canEdit(),
			'canPublish' => false,
			'_embedded' => ['items' => []]
		];

		// Before presenting the changeset to the client,
		// synchronise it with new changes.
		try {
			$changeSet->sync();
			$hal['Description'] = $changeSet->getDescription();
			$hal['canPublish'] = $changeSet->canPublish();

			foreach($changeSet->Changes() as $changeSetItem) {
				if(!$changeSetItem) {
					continue;
				}

				/** @var ChangesetItem $changeSetItem */
				$resource = $this->getChangeSetItemResource($changeSetItem);
				$hal['_embedded']['items'][] = $resource;
			}
			$hal['ChangesCount'] = count($hal['_embedded']['items']);

		// An unexpected data exception means that the database is corrupt
		} catch(UnexpectedDataException $e) {
			$hal['Description'] = 'Corrupt database! ' . $e->getMessage();
			$hal['ChangesCount'] = '-';
		}
		return $hal;
	}

	/**
	 * Build item resource from a changesetitem
	 *
	 * @param ChangeSetItem $changeSetItem
	 * @return array
	 */
	protected function getChangeSetItemResource(ChangeSetItem $changeSetItem) {
		$baseClass = DataObject::getSchema()->baseDataClass($changeSetItem->ObjectClass);
		$baseSingleton = DataObject::singleton($baseClass);
		$thumbnailWidth = (int)$this->config()->thumbnail_width;
		$thumbnailHeight = (int)$this->config()->thumbnail_height;
		$hal = [
			'_links' => [
				'self' => [
					'href' => $this->ItemLink($changeSetItem->ID)
				]
			],
			'ID' => $changeSetItem->ID,
			'Created' => $changeSetItem->Created,
			'LastEdited' => $changeSetItem->LastEdited,
			'Title' => $changeSetItem->getTitle(),
			'ChangeType' => $changeSetItem->getChangeType(),
			'Added' => $changeSetItem->Added,
			'ObjectClass' => $changeSetItem->ObjectClass,
			'ObjectID' => $changeSetItem->ObjectID,
			'BaseClass' => $baseClass,
			'Singular' => $baseSingleton->i18n_singular_name(),
			'Plural' => $baseSingleton->i18n_plural_name(),
			'Thumbnail' => $changeSetItem->ThumbnailURL($thumbnailWidth, $thumbnailHeight),
		];
		// Get preview urls
		$previews = $changeSetItem->getPreviewLinks();
		if($previews) {
			$hal['_links']['preview'] = $previews;
		}

		// Get edit link
		$editLink = $changeSetItem->CMSEditLink();
		if($editLink) {
			$hal['_links']['edit'] = [
				'href' => $editLink,
			];
		}

		// Depending on whether the object was added implicitly or explicitly, set
		// other related objects.
		if($changeSetItem->Added === ChangeSetItem::IMPLICITLY) {
			$referencedItems = $changeSetItem->ReferencedBy();
			$referencedBy = [];
			foreach($referencedItems as $referencedItem) {
				$referencedBy[] = [
					'href' => $this->SetLink($referencedItem->ID)
				];
			}
			if($referencedBy) {
				$hal['_links']['referenced_by'] = $referencedBy;
			}
		}

		return $hal;
	}

	/**
	 * Gets viewable list of campaigns
	 *
	 * @return SS_List
	 */
	protected function getListItems() {
		return ChangeSet::get()
			->filter('State', ChangeSet::STATE_OPEN)
			->filterByCallback(function($item) {
				/** @var ChangeSet $item */
				return ($item->canView());
			});
	}


	/**
	 * REST endpoint to get a campaign.
	 *
	 * @param HTTPRequest $request
	 *
	 * @return HTTPResponse
	 */
	public function readCampaign(HTTPRequest $request) {
		$response = new HTTPResponse();

		if ($request->getHeader('Accept') == 'text/json') {
			$response->addHeader('Content-Type', 'application/json');
			if (!$request->param('Name')) {
				return (new HTTPResponse(null, 400));
			}

			/** @var ChangeSet $changeSet */
			$changeSet = ChangeSet::get()->byID($request->param('ID'));
			if(!$changeSet) {
				return (new HTTPResponse(null, 404));
			}

			if(!$changeSet->canView()) {
				return (new HTTPResponse(null, 403));
			}

			$body = Convert::raw2json($this->getChangeSetResource($changeSet));
			return (new HTTPResponse($body, 200))
				->addHeader('Content-Type', 'application/json');
		} else {
			return $this->index($request);
		}
	}

	/**
	 * REST endpoint to delete a campaign.
	 *
	 * @param HTTPRequest $request
	 *
	 * @return HTTPResponse
	 */
	public function deleteCampaign(HTTPRequest $request) {
		// Check security ID
		if (!SecurityToken::inst()->checkRequest($request)) {
			return new HTTPResponse(null, 400);
		}

		$id = $request->param('ID');
		if (!$id || !is_numeric($id)) {
			return (new HTTPResponse(null, 400));
		}

		$record = ChangeSet::get()->byID($id);
		if(!$record) {
			return (new HTTPResponse(null, 404));
		}

		if(!$record->canDelete()) {
			return (new HTTPResponse(null, 403));
		}

		$record->delete();

		return (new HTTPResponse(null, 204));
	}

	/**
	 * REST endpoint to publish a {@link ChangeSet} and all of its items.
	 *
	 * @param HTTPRequest $request
	 *
	 * @return HTTPResponse
	 */
	public function publishCampaign(HTTPRequest $request) {
		// Protect against CSRF on destructive action
		if(!SecurityToken::inst()->checkRequest($request)) {
			return (new HTTPResponse(null, 400));
		}

		$id = $request->param('ID');
		if(!$id || !is_numeric($id)) {
			return (new HTTPResponse(null, 400));
		}

		/** @var ChangeSet $record */
		$record = ChangeSet::get()->byID($id);
		if(!$record) {
			return (new HTTPResponse(null, 404));
		}

		if(!$record->canPublish()) {
			return (new HTTPResponse(null, 403));
		}

		try {
			$record->publish();
		} catch(LogicException $e) {
			return (new HTTPResponse(json_encode(['status' => 'error', 'message' => $e->getMessage()]), 401))
				->addHeader('Content-Type', 'application/json');
		}

		return (new HTTPResponse(
			Convert::raw2json($this->getChangeSetResource($record)),
			200
		))->addHeader('Content-Type', 'application/json');
	}

	/**
	 * Url handler for edit form
	 *
	 * @param HTTPRequest $request
	 * @return Form
	 */
	public function DetailEditForm($request) {
		// Get ID either from posted back value, or url parameter
		$id = $request->param('ID') ?: $request->postVar('ID');
		return $this->getDetailEditForm($id);
	}

	/**
	 * @todo Use GridFieldDetailForm once it can handle structured data and form schemas
	 *
	 * @param int $id
	 * @return Form
	 */
	public function getDetailEditForm($id) {
		// Get record-specific fields
		$record = null;
		if($id) {
			$record = ChangeSet::get()->byID($id);
			if(!$record || !$record->canView()) {
				return null;
			}
		}

		if(!$record) {
			$record = ChangeSet::singleton();
		}

		$fields = $record->getCMSFields();

		// Add standard fields
		$fields->push(HiddenField::create('ID'));
		$form = Form::create(
			$this,
			'DetailEditForm',
			$fields,
			FieldList::create(
				FormAction::create('save', _t('CMSMain.SAVE', 'Save'))
					->setIcon('save'),
				FormAction::create('cancel', _t('LeftAndMain.CANCEL', 'Cancel'))
					->setUseButtonTag(true)
			),
			new RequiredFields('Name')
		);

		// Load into form
		if($id && $record) {
			$form->loadDataFrom($record);
		}
		// Configure form to respond to validation errors with form schema
		// if requested via react.
		$form->setValidationResponseCallback(function(ValidationResult $errors) use ($form, $record) {
			$schemaId = Controller::join_links(
				$this->Link('schema/DetailEditForm'),
				$record->isInDB() ? $record->ID : ''
			);
			return $this->getSchemaResponse($schemaId, $form, $errors);
		});

		return $form;
	}

	/**
	 * Gets user-visible url to edit a specific {@see ChangeSet}
	 *
	 * @param $itemID
	 * @return string
	 */
	public function SetLink($itemID) {
		return Controller::join_links(
			$this->Link('set'),
			$itemID
		);
	}

	/**
	 * Gets user-visible url to edit a specific {@see ChangeSetItem}
	 *
	 * @param int $itemID
	 * @return string
	 */
	public function ItemLink($itemID) {
		return Controller::join_links(
			$this->Link('item'),
			$itemID
		);
	}

	public function providePermissions() {
		return array(
			"CMS_ACCESS_CampaignAdmin" => array(
				'name' => _t('CMSMain.ACCESS', "Access to '{title}' section", array('title' => static::menu_title())),
				'category' => _t('Permission.CMS_ACCESS_CATEGORY', 'CMS Access'),
				'help' => _t(
					'CampaignAdmin.ACCESS_HELP',
					'Allow viewing of the campaign publishing section.'
				)
			)
		);
	}

}