<?php namespace ProcessWire;

/**
 * ProcessWire Page Export and Import
 *
 * ProcessWire 3.x, Copyright 2017 by Ryan Cramer
 * https://processwire.com
 * 
 * Note: this module supports page-edit-export and page-edit-import permissions, but currently the module is 
 * designed only for use by superuser, so don't bother adding those permissions at present. 
 * 
 * @todo ZIP file support
 * @todo Repeater support
 * @todo PageTable support
 *
 */

class ProcessPagesExportImport extends Process {
	
	public static function getModuleInfo() {
		return array(
			'title' => 'Pages Export/Import',
			'summary' => 'Enables exporting and importing of pages. Development version, not yet recommended for production use.',
			'version' => 1,
			'author' => 'Ryan Cramer',
			'icon' => 'paper-plane-o',
			'permission' => 'page-edit-export', 
			'page' => array(
				'name' => 'export-import',
				'parent' => 'page',
				'title' => 'Export/Import'
			)
		);
	}
	
	const debug = false;

	/**
	 * @var PagesExportImport
	 * 
	 */
	protected $exportImport;

	/**
	 * Main execution handler
	 * 
	 * @return string
	 * @throws \Exception
	 * 
	 */
	public function ___execute() {
		
		if(!$this->wire('user')->isSuperuser()) {
			throw new WirePermissionException($this->_('Export/import is currently only available to superuser')); 
		}
		
		$this->exportImport = new PagesExportImport();
		$this->wire($this->exportImport);
		$this->exportImport->cleanupFiles(600);

		$input = $this->wire('input');
		$user = $this->wire('user');
		$breadcrumbLabel = $this->wire('page')->title;
		
		try {
			if($input->post('submit_export')) {
				if($user->hasPermission('page-edit-export')) {
					$this->breadcrumb('./', $breadcrumbLabel);
					$this->headline($this->_('Export'));
					return $this->processExport();
				}
			} else if($input->post('submit_import') || $input->post('submit_commit_import') || $input->post('submit_test_import')) {
				if($user->hasPermission('page-edit-import')) {
					$this->breadcrumb('./', $breadcrumbLabel);
					$this->headline($this->_('Import'));
					$form = $this->processImport();
					return $form->render();
				}
			} else {
				/*
				$this->warning(
					'Please note this is a development version of pages export/import ' . 
					'and not yet recommended for production use.'
				);
				*/
				$form = $this->buildForm();
				return $form->render();
			}
		} catch(\Exception $e) {
			if(self::debug) throw $e;
			$this->error($e->getMessage());
			$this->wire('session')->redirect($this->wire('page')->url); 
		}
		
		return '';
	}

	/**
	 * Build the main import/export form 
	 * 
	 * @param string $tab Optionally specify which tab to include, “export” or “import”
	 * @return InputfieldForm|InputfieldWrapper
	 * 
	 */
	protected function buildForm($tab = '') {
	
		/** @var Modules $modules */
		$modules = $this->wire('modules');
		$modules->get('JqueryWireTabs'); 
		/** @var User $user */
		$user = $this->wire('user');
	
		/** @var InputfieldForm $form */
		$form = $modules->get('InputfieldForm');
		$form->attr('id', 'ProcessPagesExportImport');
		$form->attr('method', 'post'); 
		$form->attr('enctype', 'multipart/form-data');
		
		if($user->hasPermission('page-edit-export')) {
			if(!$tab || $tab == 'export') $form->add($this->buildExportTab());
		}
		
		if($user->hasPermission('page-edit-import')) {
			if(!$tab || $tab == 'import') $form->add($this->buildImportTab());
		}
		
		return $form;
	}

	/**
	 * Build the “import” tab
	 * 
	 * @return InputfieldWrapper
	 * 
	 */
	protected function buildImportTab() {
	
		/** @var Modules $modules */
		$modules = $this->wire('modules');

		/** @var InputfieldWrapper $tab */
		$tab = $this->wire(new InputfieldWrapper());
		$tab->attr('id+name', 'tab_import');
		$tab->attr('title', $this->_('Import'));
		$tab->addClass('WireTab');

		/** @var InputfieldTextarea $f */
		$f = $modules->get('InputfieldTextarea'); 
		$f->name = 'import_json';
		$f->label = $this->_('Import from JSON string'); 
		$f->icon = 'scissors';
		$f->description = $this->_('Paste in the JSON string previously exported from this tool.'); 
		$tab->add($f);

		/** @var InputfieldFile $f */
		$f = $modules->get('InputfieldFile');
		$f->name = 'import_zip';
		$f->label = $this->_('Import from ZIP file upload') . " (experimental)";
		$f->extensions = 'zip';
		$f->icon = 'upload';
		$f->maxFiles = 1;
		$f->unzip = 0;
		$f->overwrite = false;
		$f->setMaxFilesize('10g');
		$f->collapsed = Inputfield::collapsedYes;
		$f->destinationPath = $this->exportImport->getExportPath();
		$tab->add($f);

		/** @var InputfieldSubmit $f */
		$f = $modules->get('InputfieldSubmit');
		$f->attr('name', 'submit_import');
		$f->val($this->_('Continue')); 
		$f->icon = 'angle-right';
		$tab->add($f);
	
		return $tab;
	}
	
	/**
	 * Process a submitted import and return form with summary data
	 * 
	 * @return InputfieldForm
	 * @throws WireException
	 * 
	 */
	protected function processImport() {
		
		/** @var WireInput $input */
		$input = $this->wire('input');

		/** @var InputfieldWrapper|InputfieldForm $importTab */
		$importTab = $this->buildForm('import');
	
		$submitCommit = $input->post('submit_commit_import') ? true : false;
		$submitTest = $input->post('submit_test_import') ? true : false;
		$submitZIP = !empty($_FILES['import_zip']) && !empty($_FILES['import_zip']['name'][0]);
		$fileField = null;
		$filesPath = $this->wire('session')->getFor($this, 'filesPath'); 
		$jsonFile = '';
		$a = null;
		
		if($submitZIP) {
			// ZIP file import
			$importTab->processInput($input->post);
			$fileField = $importTab->getChildByName('import_zip');
			$zipFile = $this->exportImport->getExportPath() . $fileField->value->first()->name;
			if(!$zipFile || !is_file($zipFile)) throw new WireException('No ZIP file found: ' . $zipFile); 
			$unzipPath = $this->exportImport->getExportPath('import-zip'); 
			$zipFileItems = $this->wire('files')->unzip($zipFile, $unzipPath);
			$this->wire('files')->unlink($zipFile); 
			if(empty($zipFileItems)) throw new WireException("No files found in ZIP"); 
			$jsonFile = $unzipPath . "pages.json";
			$this->wire('session')->setFor($this, 'filesPath', $unzipPath);
			
		} else if(!empty($_POST['import_json'])) {
			// JSON import
			$importTab->processInput($input->post);
			$json = $importTab->getChildByName('import_json')->val(); 
			if(empty($json)) throw new WireException($this->_('No import data found')); 
			$a = json_decode($json, true);
			$this->wire('session')->setFor($this, 'filesPath', ''); 
			
		} else if($filesPath) {
			// ZIP import commit or test
			$jsonFile = $filesPath . "pages.json";
		}
		
		if($jsonFile) {
			if(!is_file($jsonFile)) throw new WireException("No pages.json found in ZIP file"); 
			$a = json_decode(file_get_contents($jsonFile), true);
		}

		if(!is_array($a)) throw new WireException($this->_('Invalid import data')); 
		if(empty($a['type']) || $a['type'] != 'ProcessWire:PageArray') throw new WireException("Invalid import type: $a[type]");
		if(empty($a['pages'])) throw new WireException("No pages found to import");
		if(empty($a['fields'])) throw new WireException("Import data contains no fields information");
	
		// adjust import data as needed
		$this->adjustImportData($a); 
		
		// populate an _info array to $a
		$this->exportImport->getImportInfo($a);
		$info =& $a['_info'];
		
		// expand the original form with more import options
		$form = $this->buildImportForm($importTab, $a);
	
		// determine whether we are testing, committing or continuing after 1st submit
		if($submitCommit || $submitTest) {
			// form has been submitted for testing or commit
			$qty = $this->processImportSubmit($form, $a, $submitCommit);
			if($submitCommit) {
				$form->description = sprintf($this->_n('Imported %d page', 'Imported %d pages', $qty), $qty);
				foreach($form->children() as $f) {
					if($f->name != 'import_items') $form->remove($f);
				}
			} else {
				$form->description = sprintf($this->_n('Tested import of %d page', 'Tested import of %d pages', $qty), $qty);
			}

		} else {
			// first submission from import tab
			$qty = count($a['pages']);
			$form->description = sprintf($this->_n('Found %d page for import', 'Found %d pages for import', $qty), $qty);
		}
	
		if($qty > 1) {
			$form->description .= ' (' .
				sprintf($this->_('%d new, %d existing'), $info['numNew'], $info['numExisting']) . ')';
		}

		return $form;
	}

	/**
	 * Handles execution of PagesExportImport for test or commit imports
	 * 
	 * @param InputfieldForm $form
	 * @param array $a Import data
	 * @param bool $submitCommit Whether or not to commit the import
	 * @return int Quantity of pages imported
	 * 
	 */
	protected function processImportSubmit(InputfieldForm $form, array &$a, $submitCommit) {
		
		// FYI: 
		// $a = array(
		//   'type' => 'ProcessWire:PageArray',
		//   'version' => '...',
		//   'pagination' => array(),
		//   'pages' => array( page import data ), 
		//   'fields' => array( fields information ), 
		// );
		set_time_limit(3600);

		/** @var WireInput $input */
		$input = $this->wire('input');
		
		$form->processInput($input->post);
		
		/** @var InputfieldFieldset $fieldset */
		$fieldset = $form->getChildByName('import_items');
		$importMode = $form->getChildByName('import_mode')->val();
		$fieldNames = $form->getChildByName('import_fields')->val();
		$qty = 0;
	
		$options = array(
			'update' => $importMode == 'all' || $importMode == 'update',
			'create' => $importMode == 'all' || $importMode == 'create',
			'saveOptions' => array('adjustName' => true, 'quiet' => true),
			'fieldNames' => $fieldNames, 
			'replaceFields' => isset($a['_replaceFields']) ? $a['_replaceFields'] : array(), 
			'commit' => $submitCommit,
			'debug' => self::debug,
			'changeTemplate' => false,
			'changeParent' => false,
			'changeName' => in_array('name', $fieldNames),
			'changeStatus' => in_array('status', $fieldNames),
			'changeSort' => in_array('sort', $fieldNames),
			'filesPath' => $this->wire('session')->getFor($this, 'filesPath'), 
			'originalHost' => isset($a['host']) ? $a['host'] : $this->wire('config')->httpHost, 
			'originalRootUrl' => isset($a['url']) ? $a['url'] : $this->wire('config')->urls->root,
		);
		
		foreach($a['pages'] as $key => $item) {
			$id = $item['settings']['id'];
			if($submitCommit && !$input->post("confirm$id")) continue;
			$page = $this->processImportItemToPage($item, $options);
			if(!$page instanceof NullPage) $qty++;
			$fieldset->add($this->buildImportItemSummary($item, $page, $options));
		}
		
		if(!$qty && $fieldset->children()->count() == 0) {
			$fieldset->description = $this->_('No import details to display');
		}
		
		return $qty; 
	}

	/**
	 * Build a fieldset of inputs for missing resource replacement and swap in new values when selected
	 * 
	 * @param array $a Import data array, is updated by this method
	 * @return InputfieldFieldset
	 * 
	 */
	protected function identifyMissingResources(array &$a) {
		
		/** @var Sanitizer $sanitizer */
		$sanitizer = $this->wire('sanitizer');

		/** @var Modules $modules*/
		$modules = $this->wire('modules');

		/** @var Templates $templates */
		$templates = $this->wire('templates');
		
		/** @var Fields $fields */
		$fields = $this->wire('fields');
		
		/** @var Pages $pages */
		$pages = $this->wire('pages');
		
		/** @var WireInput $input */
		$input = $this->wire('input');
	
		$numFatalItems = 0;
		$missingItems = array();
		$info = $a['_info'];
	
		// Missing templates
		foreach($info['missingTemplates'] as $templateName) {
			$inputName = "template_$templateName";
			$inputValue = $input->post($inputName);
			$template = null;
			if($inputValue) {
				$inputValue = $sanitizer->name($inputValue);
				$template = $templates->get($inputValue);
			}
			
			/** @var InputfieldSelect $f */
			$f = $modules->get('InputfieldSelect');
			$f->description =
				sprintf(
					$this->_('Pages having template “%s” cannot be imported because that template does not exist here.'),
					$templateName
				) . ' ' . $this->_('Select a template to substitute when creating these pages.');
			
			foreach($this->wire('templates') as $t) {
				$f->addOption($t->name);
			}
			
			if($template) {
				// swap in new template
				foreach($a['pages'] as $key => $item) {
					if($item['template'] === $templateName) {
						$a['pages'][$key]['template'] = $template->name;
					}
				}
				$f->label = sprintf($this->_('OK: Replacing TEMPLATE “%1$s” with “%2$s”'), $templateName, $template->name); 
				$f->collapsed = Inputfield::collapsedYes; 
				$f->icon = 'check';
			} else {
				$f->icon = 'cubes';
				$f->label = sprintf($this->_('Select replacement for TEMPLATE named “%s”'), $templateName);
				$numFatalItems++;
			}
			
			$f->attr('name', $inputName);
			$f->attr('value', $template ? $template->name : '');
			$missingItems[] = $f;
		}
	
		// Missing fields
		$replaceFields = array();
		$importFields = $input->post('import_fields'); 
		
		foreach($info['missingFields'] as $fieldName) {
			if($importFields && !in_array($fieldName, $importFields)) continue; 
			
			$inputName = "field_$fieldName";
			$inputValue = $input->post($inputName);
			$field = null;
			
			if($inputValue) {
				$inputValue = $sanitizer->fieldName($inputValue);
				$field = $fields->get($inputValue);
			}
			
			/** @var InputfieldSelect $f */
			$fieldtypeClass = $a['fields'][$fieldName]['type'];
			$fieldtypeLabel = str_replace('Fieldtype', '', $fieldtypeClass);
			$f = $modules->get('InputfieldSelect');
			
			$f->description = sprintf(
					$this->_('A field named “%s” of type *%s* appears in the import data, but does not exist locally.'),
					$fieldName,
					$fieldtypeLabel
				) . ' ' . $this->_('If you want to import this field, select a replacement field here.'); 
			
			if($field) {
				// swap in new field 
				$replaceFields[$fieldName] = $field->name; 
				/*
				 * // Moved to options[replaceFields], this code for reference: 
				foreach($a['pages'] as $key => $item) {
					if(!isset($item['data'][$fieldName])) continue;
					if(isset($item['data'][$field->name])) continue;
					$item['data'][$field->name] = $item['data'][$fieldName];
					unset($item['data'][$fieldName]);
					$a['pages'][$key] = $item;
				}
				*/
				$f->icon = 'check';
				$f->collapsed = Inputfield::collapsedYes;
				$f->label = sprintf($this->_('OK: Replacing FIELD “%1$s” with “%2$s”'), $fieldName, $field->name);
			} else {
				$f->label = sprintf($this->_('Select replacement for FIELD named “%s”'), $fieldName);
				$f->icon = 'cube';
			}
			
			$f->addOption(''); 
			$optionsRecommended = array();
			$optionsOther = array();
			
			foreach($this->wire('fields') as $_field) {
				/** @var Field $_field */
				if($_field->type->className() == $fieldtypeClass && !$_field->hasFlag(Field::flagSystem)) {
					$optionsRecommended[$_field->name] = $_field->name;
				} else {
					$optionsOther[$_field->name] = $_field->name;
				}
			}
			
			if(count($optionsRecommended)) {
				$f->addOption($this->_('Potential replacement fields'), $optionsRecommended);
				$f->addOption($this->_('Other fields (may not be compatible)'), $optionsOther);
			} else {
				$f->addOptions($optionsOther);
			}
			
			$f->attr('name', $inputName);
			$f->attr('value', $field ? $field->name : '');
			$missingItems[] = $f;
		}
		$a['_replaceFields'] = $replaceFields;
		
		// Missing parents
		$updatedParents = array();
		
		foreach($info['missingParents'] as $parentPath) {
			
			$inputName = "parent_" . str_replace('/', '__', trim($parentPath, '/'));
			$inputValue = $input->post($inputName);
			$parent = null;
			
			if($inputValue) {
				$inputValue = (int) $inputValue; 
				$parent = $pages->get($inputValue);
				if(!$parent->id) $parent = null;
			}
			
			if(!$parent) {
				$skipParent = false;
				foreach($updatedParents as $updatedPath => $updatedPage) {
					if(strpos($parentPath, $updatedPath) === 0) {
						$skipParent = true;
					}
				}
				if($skipParent) continue;
			}

			/** @var InputfieldPageListSelect $f */
			$f = $modules->get('InputfieldPageListSelect');
			$f->startLabel = $this->_('Choose new parent'); 
			$f->description =
				sprintf(
					$this->_('Pages having parent “%s” cannot be imported because that page does not exist here.'),
					$parentPath
				) . ' ' . $this->_('Select a parent page to use instead creating these pages.');

			if($parent) {
				// swap in new parent
				foreach($a['pages'] as $key => $item) {
					if(strpos($item['path'], $parentPath) === 0) {
						$path = $parent->path . substr($item['path'], strlen($parentPath)); 
						$a['pages'][$key]['path'] = $path;
					}
				}
				$f->label = sprintf($this->_('OK: Replacing PARENT “%1$s” with “%2$s”'), $parentPath, $parent->path);
				$f->collapsed = Inputfield::collapsedYes;
				$f->icon = 'check';
				$updatedParents[$parent->path] = $parent;
			} else {
				$f->icon = 'female';
				$f->label = sprintf($this->_('Select replacement for PARENT named “%s”'), $parentPath);
				$numFatalItems++;
			}

			$f->attr('name', $inputName);
			$f->attr('value', $parent ? $parent->id : '');
			$missingItems[] = $f;
		}

		if(count($missingItems)) {
			/** @var InputfieldFieldset $fieldset */
			$fieldset = $modules->get('InputfieldFieldset');
			$fieldset->label = $this->_('Resource conflicts');
			$fieldset->icon = 'warning';

			foreach($missingItems as $f) {
				$fieldset->add($f);
			}
		} else {
			$fieldset = $this->wire(new InputfieldWrapper());
		}
		
		if($numFatalItems) $a['_noCommit'] = true;
		
		return $fieldset; 
	}
	
	/**
	 * Adjust import data as needed to match specific import options
	 *
	 * @param array $a Import data to adjust
	 * @throws WireException
	 *
	 */
	protected function adjustImportData(&$a) {
		
		/** @var WireInput $input */
		$input = $this->wire('input');
		
		$importParentID = (int) $input->post('import_parent');
		$importParentType = $input->post('import_parent_type') === 'direct' ? 'direct' : 'below';
		$importParent = $importParentID ? $this->wire('pages')->get($importParentID) : null;
		$importParentPath = $importParent ? $importParent->path() : '';
		
		if($importParent && !$importParentID) throw new WireException("Unknown parent: $importParentID");
		
		if($importParentID && $importParentType === 'direct') {
			// update paths to make pages direct children of selected parent
			foreach($a['pages'] as $key => $item) {
				$a['pages'][$key]['path'] = $importParentPath . $item['settings']['name'] . '/';
			}

		} else if($importParentID) {
			// update import to all go under a selected parent
			// locate all page paths
			$importPaths = array();
			$missingParentPaths = array();
			foreach($a['pages'] as $item) {
				$path = rtrim($item['path'], '/') . '/';
				$importPaths[$path] = $item['settings']['id'];
			}
			// update page paths as necessary to ensure parents exist
			foreach($a['pages'] as $item) {
				$parts = explode('/', trim($item['path'], '/'));
				array_pop($parts);
				$parentPath = count($parts) ? '/' . implode('/', $parts) . '/' : '/';
				if(isset($importPaths[$parentPath])) {
					// parent of this page will also be imported
				} else {
					// this page's parent is not part of the import
					$missingParentPaths[] = $parentPath;
				}
			}
			$importParentPath = $importParent->path();
			foreach($a['pages'] as $key => $item) {
				$path = $item['path'];
				foreach($missingParentPaths as $missingParentPath) {
					if(strpos($path, $missingParentPath) === 0) {
						$path = rtrim($importParentPath . substr($path, strlen($missingParentPath)), '/') . '/';
					}
				}
				if($path == $item['path']) {
					if(strpos($path, $importParentPath) === 0) {
						// parent already present in path
					} else {
						$path = $importParentPath . trim($path, '/') . '/';
					}
				}
				$a['pages'][$key]['path'] = $path;
			}
		}
	}

	/**
	 * Import item to a Page and return it 
	 * 
	 * @param array $item Import data for 1 page
	 * @param array $options Options for importer
	 * @return NullPage|Page
	 * 
	 */
	protected function processImportItemToPage(array $item, array $options) {
		try {
			$page = $this->exportImport->arrayToPage($item, $options);
		} catch(\Exception $e) {
			$page = new NullPage();
			$page->error($e->getMessage());
		}
		return $page; 
	}

	/**
	 * Build the import form that appears after submitting from Import tab
	 * 
	 * @param InputfieldForm $tab The form that was used for the Import tab
	 * @param array $a Array of import data
	 * @return InputfieldForm 
	 * 
	 */
	protected function buildImportForm(InputfieldForm $tab, array &$a) {
	
		$modules = $this->wire('modules');
		
		$form = $modules->get('InputfieldForm');
		$form->attr('id', 'import-form');
		$form->description = $this->_('Import summary');

		// hide import data fields
		if(!self::debug) {
			foreach(array('import_json', 'import_zip') as $name) {
				$f = $tab->getChildByName($name);
				if($f) $f->wrapAttr('style', 'display:none');
			}
		}

		// copy fields from tab to new form
		/** @var InputfieldFieldset $importTab */
		$importTab = $tab->getChildByName('tab_import'); 
		foreach($importTab->children() as $f) {
			if($f->attr('name') == 'import_zip') {
				continue;
			} else if($f instanceof InputfieldSubmit) {
				continue;
			} else {
				$form->add($f);
			}
		}
		
		$form->add($this->identifyMissingResources($a)); 
	
		/** @var InputfieldRadios $f */
		$f = $modules->get('InputfieldRadios');
		$f->name = 'import_mode';
		$f->label = $this->_('Import mode');
		$f->icon = 'edit';
		$f->addOption('all',
			$this->_('Create new pages and update existing pages')
		);
		$f->addOption('create',
			$this->_('Create new pages only') . ' ' .
			"[span.detail] (" .
			$this->_('Skip over pages in the import that already exist') .
			") [/span]"
		);
		$f->addOption('update',
			$this->_('Update existing pages only') . ' ' .
			"[span.detail] (" .
			$this->_('Skip over pages in the import that do not already exist') .
			") [/span]"
		);
		$f->attr('value', 'all');
		$form->add($f);

		/** @var InputfieldPageListSelect $f */
		$f = $modules->get('InputfieldPageListSelect');
		$f->attr('name', 'import_parent');
		$f->label = $this->_('Import pages below parent');
		$f->description = $this->_('When specified, pages will import to the parent page selected here.');
		$f->collapsed = Inputfield::collapsedBlank;
		$f->icon = 'female';
		$f->showIf = 'import_mode!=update';
		$f->startLabel = $this->_('Choose parent'); 
		$checkedDirect = $this->wire('input')->post('import_parent_type') == 'direct' ? "checked='checked'" : '';
		$checkedBelow = $checkedDirect ? '' : "checked='checked'"; 
		$f->appendMarkup = 
			"<p class='InputfieldRadios'>" . 
				"<label style='display:block'>" . 
					"<input type='radio' name='import_parent_type' $checkedBelow value='below'>" .
					"<span class='pw-no-select'>" . 
						$this->_('Import pages into selected parent and maintain page path structure below it') . 
					"</span>" . 
				"</label>" . 
				"<label style='display:block'>" . 
					"<input type='radio' name='import_parent_type' $checkedDirect value='direct'>" .
					"<span class='pw-no-select'>" . 
						$this->_('Import pages as children of selected parent page only') .
					"</span>" . 
				"</label>" . 
			"</p>";
			
		$form->add($f);

		/** @var InputfieldCheckboxes $f */
		$f = $modules->get('InputfieldCheckboxes');
		$f->attr('name', 'import_fields');
		$f->label = $this->_('Fields allowed in import');
		$f->description = $this->_('The following fields were found in the import data.');  
		$f->description .= ' ' . $this->_('Uncheck any fields that you want to skip during import.'); 
		$f->icon = 'cube';
		$f->table = true;
		$f->thead =
			$this->_('Name') . '|' .
			$this->_('Label') . '|' .
			$this->_('Type');
		$value = array('name', 'status', 'sort');
		
		foreach($a['fields'] as $fieldName => $fieldInfo) {
			$typeName = str_replace('Fieldtype', '', $fieldInfo['type']);
			$f->addOption($fieldName, "$fieldName|$fieldInfo[label]|$typeName");
			$value[] = $fieldName;
		}
		$f->addOption('name', "name|" . $this->_('Page name') . "|System");
		$f->addOption('status', "status|" . $this->_('Page status') . "|System");
		$f->addOption('sort', "sort|" . $this->_('Page sort index') . "|System"); 
		$f->attr('value', $value); 
		if(!$this->wire('input')->post('submit_import')) $f->collapsed = Inputfield::collapsedYes;
		$form->add($f);
		
		$submitTest = $this->wire('input')->post('submit_test_import') ? true : false;
		$submitCommit = $this->wire('input')->post('submit_commit_import') ? true : false;

		if($submitCommit || $submitTest) {
			$fieldset = $modules->get('InputfieldFieldset');
			$fieldset->attr('name', 'import_items');
			$fieldset->label = $this->_('Import pages');
			$fieldset->icon = 'copy';
			$form->prepend($fieldset);
		}
		
		/** @var InputfieldSubmit $f */
		$f = $modules->get('InputfieldSubmit');
		$f->attr('name', 'submit_test_import');
		$f->val($this->_('Test Import'));
		$f->icon = 'flask';
		$f->showInHeader(true);
		$form->add($f);
	
		if(($submitTest || $submitCommit) && empty($a['_noCommit'])) {
			$f = $modules->get('InputfieldSubmit');
			$f->attr('name', 'submit_commit_import');
			$f->val($this->_('Commit Import'));
			$f->icon = 'database';
			$f->showInHeader(true);
			$form->add($f);
		}

		return $form;
	}

	/**
	 * Build a summary InputfieldMarkup for a single item/Page
	 * 
	 * @param array $item Import item array
	 * @param Page|NullPage $page Resulting Page object
	 * @param array $options Import options that were passed to PagesExportImport import() method
	 * @return InputfieldMarkup
	 * 
	 */
	protected function buildImportItemSummary(array $item, Page $page, array $options) {

		$sanitizer = $this->wire('sanitizer');
		$changes = $page->get('_importChanges');
		$importType = $page->get('_importType');
		$languages = $this->wire('languages');
		$numChanges = count($changes);
		$originalID = (int) $item['settings']['id'];
		$out = '';
		
		static $n = 0;
		$n++;
		
		$f = $this->wire('modules')->get('InputfieldMarkup');
		$f->addClass('import-form-item');
		$f->label = "$n. ";
		
		if($importType == 'create') {
			$f->label .= sprintf($this->_('Create new page: %s'), $page->get('_importPath'));
			$f->icon = 'plus-square';
			$page->message(sprintf($this->_('Template: %s'), $page->template->name));
		} else if($importType == 'update') {
			$f->label .= sprintf($this->_('Update existing page: %s'), $page->get('_importPath'));
			$f->icon = 'pencil-square';
		} else if($page instanceof NullPage) {
			$f->label .= sprintf($this->_('Page: %s – Fail'), $item['path']);
			$f->icon = 'times-rectangle';
		} else {
			$f->label .= sprintf($this->_('Page: %s'), $item['path']);
			$f->icon = 'question-circle';
		}
		
		if($numChanges) {
			foreach($changes as $key => $change) {
				// i.e. 'field_name__' as disguised change
				if(substr($change, -2) == '__') $changes[$key] = substr($change, 0, -2); 
			}
			if($languages) {
				// indicate language in name and status changes
				foreach($changes as $key => $change) {
					if(preg_match('/^(name|status)(\d+)$/', $change, $matches)) {
						$language = $languages->get((int) $matches[2]); 
						if($language && $language->id) $changes[$key] = $matches[1] . " ($language->name)";
					}
				}
			}
			if($importType == 'create') {
				$page->message($this->_('Populated fields:') . ' ' . implode(', ', $changes));
			} else {
				$page->message($this->_('Changed fields:') . ' ' . implode(', ', $changes));
			}
		} else if(!$page instanceof NullPage) {
			$page->warning($this->_('No changes detected'));
		}
		
		if($page instanceof NullPage) {
			$page->error($this->_('Page cannot be imported'));
			$f->addClass('import-form-item-fail'); 
			$f->collapsed = Inputfield::collapsedYes;
		} else {
			if($options['commit']) $page->message($this->_('Import successful'));
		}
		
		foreach(array('errors', 'warnings', 'messages') as $noticeType) {
			$notices = $page->$noticeType('clear'); 
			foreach($notices as $notice) {
				$noticeText = $sanitizer->entities($notice->text);
				if($noticeType != 'messages') {
					$icon = $noticeType == 'errors' ? 'warning' : 'warning';
				} else {
					$icon = 'check';
				}
				$class = "import-" . trim($noticeType, 's');
				$noticeText = "<i class='fa fa-fw fa-$icon'></i> $noticeText";
				$out .= "<p class='$class'>$noticeText</p>";
			}
		}
		
		if(!$options['commit']) { 
			if($page instanceof NullPage) {
				// NullPage (error)
			} else if($numChanges) {
				// Page (success)
				$attr = "type='radio' name='confirm$originalID' class='import-confirm'";
				$val = $this->wire('input')->post("confirm$originalID");
				if(($val == $originalID || $val === null) && $numChanges) {
					$checkedYes = "checked='checked'";
					$checkedNo = "";
				} else {
					$checkedYes = "";
					$checkedNo = "checked='checked'";
				}
				$out .=
					"<p class='import-form-item-input'>" .
					"<i class='fa fa-fw fa-caret-right'></i> " .
					$this->_('Import this page?') . '&nbsp; ' .
					"<label><input $attr value='$originalID' $checkedYes />&nbsp;" . $this->_('Yes') . "</label>&nbsp; " .
					"<label><input $attr value='' $checkedNo />&nbsp;" . $this->_('No') . "</label>" .
					"</p>";
			}
		}

		$f->val($out); 
		
		return $f; 
	}

	/**
	 * Build the export tab
	 * 
	 * @return InputfieldWrapper
	 * 
	 */
	protected function buildExportTab() {

		$modules = $this->wire('modules');
		
		$tab = $this->wire(new InputfieldWrapper());
		$tab->attr('id+name', 'tab_export');
		$tab->attr('title', $this->_('Export'));
		$tab->addClass('WireTab');
		
		$f = $modules->get('InputfieldRadios');
		$f->attr('name', 'export_type'); 
		$f->label = $this->_('What pages do you want to export?'); 
		$f->icon = 'sitemap';
		$f->addOption('specific', $this->_('Pages that I select'));
		$f->addOption('parent', $this->_('Pages having parent'));
		$f->addOption('selector', $this->_('Pages matching search'));
		$tab->add($f);
		
		$f = $modules->get('InputfieldPageListSelectMultiple');
		$f->attr('name', 'pages_specific');
		$f->label = $this->_('Select pages');
		$f->description = $this->_('Select one or more pages to include in the export.');
		$f->icon = 'crosshairs';
		$f->showIf = 'export_type=specific';
		$tab->add($f);
		
		$f = $modules->get('InputfieldPageListSelect');
		$f->attr('name', 'pages_parent');
		$f->label = $this->_('Select parent page');
		$f->description = $this->_('Select the parent of the pages you want to export. The children of this page will be exported.'); 
		$f->icon = 'child';
		$f->showIf = 'export_type=parent';
		$tab->add($f);
		
		$f = $modules->get('InputfieldCheckboxes');
		$f->attr('name', 'options_parent');
		$f->label = $this->_('Additional options');
		$f->icon = 'sliders';
		$f->showIf = 'export_type=parent';
		$f->addOption('parent', $this->_('Include the parent page in the export'));
		$f->addOption('recursive', $this->_('Recursive') . ' ' .  
			'[span.detail] (' . $this->_('Exports tree of pages rather than just direct children') . ') [/span]');
		$f->addOption('hidden', $this->_('Include hidden pages'));
		$f->addOption('unpublished', $this->_('Include hidden and unpublished pages'));
		$tab->add($f);

		$f = $modules->get('InputfieldSelector');
		$f->attr('name', 'pages_selector');
		$f->label = $this->_('Build a search to match pages for export');
		$f->description = $this->_('Add one or more fields to search and match pages for export.');
		$f->icon = 'map-o';
		$f->showIf = 'export_type=selector';
		$tab->add($f);
		
		$f = $modules->get('InputfieldCheckboxes'); 
		$f->attr('name', 'export_fields'); 
		$f->label = $this->_('Export fields'); 
		$f->description = 
			$this->_('By default, all supported fields on a page are included in the export.') . ' ' . 
			$this->_('If you want your export to only include certain fields, then select them here.') . ' ' . 
			$this->_('If no selection is made, then all supported fields are included in the export.');
		$f->icon = 'cube';
		$showIf = 'export_type=specific|parent|selector';
		$f->showIf = $showIf; 
		$f->table = true;
		$f->collapsed = Inputfield::collapsedBlank;
		$f->thead = 
			$this->_('Name') . '|' . 
			$this->_('Label') . '|' . 
			$this->_('Type');
		foreach($this->getExportableFields() as $field) {
			$typeName = str_replace('Fieldtype', '', $field->type->className()); 
			$f->addOption($field->name, "$field->name|$field->label|$typeName"); 
		}
		$tab->add($f);
	
		/*
		$f = $modules->get('InputfieldRadios');
		$f->attr('name', 'export_to');
		$f->label = $this->_('How do you want to save the export?'); 
		$f->addOption('zip', $this->_('Download ZIP file'));
		$f->addOption('json', $this->_('Text for copy/paste')); 
		$f->attr('value', 'zip');
		$f->description = $this->_('Always choose the ZIP file option if you want to include file or image fields in your export.');
		$f->showIf = $showIf; 
		$f->collapsed = Inputfield::collapsedYes;
		$tab->add($f); 
		*/
		
		/** @var InputfieldSubmit $f */
		$f = $modules->get('InputfieldSubmit');
		$f->attr('name', 'submit_export');
		$f->value = $this->_('Export Now');
		$f->showIf = $showIf;
		$f->icon = 'download';
		$f->addActionValue('json', $this->_('JSON for copy/paste (default)'), 'scissors');
		$f->addActionValue('zip', $this->_('ZIP file download') . ' (experimental)', 'download');
		$tab->add($f);
		
		return $tab;
	}

	/**
	 * Process submitted export form 
	 * 
	 * @return string
	 * @throws WireException
	 * 
	 */
	protected function processExport() {
		
		// export_type: string(specific, parent, selector)
		// pages_specific: array(page IDs)
		// pages_parent: integer(page ID)
		// pages_selector: string(selector)
		// options_parent: array('parent', 'recursive')
		// export_fields: array(field names)
		// export_to: string(zip, json)
		
		set_time_limit(3600);

		/** @var Pages $pages */
		$pages = $this->wire('pages');
		/** @var WireInput $input */
		$input = $this->wire('input');

		$form = $this->buildForm();
		$form->processInput($input->post);
		/** @var InputfieldFieldset $tab */
		$tab = $form->getChildByName('tab_export');
		
		$exportType = $tab->getChildByName('export_type')->val();
		$exportFields = $tab->getChildByName('export_fields')->val();
		$exportTo = $input->post('submit_export') === 'zip' ? 'zip' : 'json';
		
		// @todo security and access control
		// @todo paginate large sets
		
		// determine pages to export
		switch($exportType) {
			case 'specific':
				$exportIDs = $tab->getChildByName('pages_specific')->val();
				$exportPages = count($exportIDs) ? $pages->getById($exportIDs) : new PageArray();
				break;
			case 'parent':
				$parentID = (int) $tab->getChildByName('pages_parent')->val();
				$exportParent = $parentID ? $pages->get($parentID) : new NullPage(); 
				if(!$exportParent->id) throw new WireException('Unable to load parent for export');
				$exportOptions = $tab->getChildByName('options_parent')->val();
				$includeMode = '';
				if(in_array('unpublished', $exportOptions)) {
					$includeMode = 'include=unpublished';
				} else if(in_array('hidden', $exportOptions)) {
					$includeMode = 'include=hidden';
				}
				if(in_array('recursive', $exportOptions)) {
					$exportPages = $pages->find("has_parent=$parentID" . ($includeMode ? ", $includeMode" : "")); 
				} else {
					$exportPages = $exportParent->children($includeMode);
				}
				if(in_array('parent', $exportOptions)) {
					$exportPages->prepend($exportParent); 
				}
				break;
			case 'selector':
				$exportSelector = $tab->getChildByName('pages_selector')->val();
				$exportPages = $pages->find($exportSelector); 
				break;
			default:
				$exportPages = new PageArray();
		}
	
		$exportCount = $exportPages->getTotal();
		if(!$exportCount) throw new WireException("No pages to export"); 
	
		$exporter = new PagesExportImport();
		$this->wire($exporter); 
		$exportOptions = array();
		if(count($exportFields)) $exportOptions['fieldNames'] = $exportFields;
		
		if($exportTo == 'json') {
			// json
			$json = $exporter->exportJSON($exportPages, $exportOptions);
			$form = $this->wire('modules')->get('InputfieldForm');
			$f = $this->wire('modules')->get('InputfieldTextarea');
			$f->attr('id+name', 'export_json');
			$f->label = $this->_('Pages export data for copy/paste');
			$f->description = sprintf(
				$this->_n('This export includes %d page.', 'This export includes %d pages.', $exportCount), 
				$exportCount
				) . ' ' . 
				$this->_('Click anywhere in the text below to select it for copy.') . ' ' . 
				$this->_('You can then paste this text to the Import tab of another installation.');
				
			$f->val($json);
			$form->add($f);
			return $form->render() . "<p><a href='./'>" . $this->_('Run another export') . "</a></p>";
			
		} else if($exportTo == 'zip') {
			// zip file download
			$zipFile = $exporter->exportZIP($exportPages, $exportOptions);
			if($zipFile) {
				$this->wire('files')->send($zipFile, array(
					'forceDownload' => true,
					'exit' => false
				));
				$this->wire('files')->unlink($zipFile);
				exit;
			} else {
				throw new WireException('Export failed during ZIP file generation');
			}
		}
		
		return '';
	}

	/**
	 * Get array of exportable fields
	 * 
	 * @return array Array of fieldName => Field object
	 * 
	 */
	protected function getExportableFields() {
		$exporter = new PagesExportImport();
		$this->wire($exporter);
		$fields = array();
		foreach($this->wire('fields') as $field) {
			if(!$field->type) continue;	
			$info = $exporter->getFieldInfo($field);
			if($info['exportable']) $fields[$field->name] = $field;
		}
		ksort($fields);
		return $fields;
	}

	/**
	 * Install module
	 * 
	 */
	public function ___install() {
		parent::___install(); 
	}

	/**
	 * Uninstall module
	 * 
	 */
	public function ___uninstall() {
		parent::___uninstall(); 
	}
	
}