// @require WFS_URL
var DBG = DBG || false

// wfsFeature json format:
/*
	{
		$fieldName:
			- string => field value
			- array of objects => ref features as objects (wfsFeature)
			- array of strings => ref features as xlink url
	}
*/

function p5WFS_ParseFeatureFieldRecurse(tagNode) { // @returns object from xml element
	var item = {}
	var i = 0
	for (i = 0; i < tagNode.children.length; i++) {
		var fieldNode = tagNode.children[i]
		console.log('DBG: parse rec ifd(' + tagNode.getAttribute('fid') + ') tagName: ', fieldNode.tagName);
		if ('p5:links' === fieldNode.tagName) {
			// <p5:links>
			//    ​<p5:next p5:typeName=​"default_db__x3A__BI_audit_KW_requested_person:​BI_audit_KW_requested_person"
			//             p5:backRefNS=​"default_db/​BI_audit_ENERGA_RUM_KONTRAHENCI_POWIAZANIA/​BI_audit_ENERGA_RUM_KONTRAHENCI_POWIAZANIA"
			//             p5:backRefPK=​"20"
			//             p5:startIndex=​"10">
			// ​"https://.../wfs-data.php/default_db/?SERVICE=WFS&amp;VERSION=1.0.0&amp;TYPENAME=default_db__x3A__BI_audit_KW_requested_person:BI_audit_KW_requested_person&amp;REQUEST=GetFeature&amp;backRefNS=default_db/BI_audit_ENERGA_RUM_KONTRAHENCI_POWIAZANIA/BI_audit_ENERGA_RUM_KONTRAHENCI_POWIAZANIA&amp;backRefPK=20&amp;backRefField=default_db__x3A__BI_audit_KW_requested_person:BI_audit_KW_requested_person&amp;startIndex=10"
			// </p5:next>​</p5:links>​
			for (var j = 0; j < fieldNode.children.length; j++) {
				var p5LinkNode = fieldNode.children[j]
				if ('p5:next' === p5LinkNode.tagName) {
					var typeName = p5LinkNode.getAttribute('p5:typeName')
					item[ typeName ].push( {
						'type': 'next',
						'@backRefNS': p5LinkNode.getAttribute('p5:backRefNS'),
						'@backRefPK': p5LinkNode.getAttribute('p5:backRefPK'),
						'@typeName': p5LinkNode.getAttribute('p5:typeName'),
						'@startIndex': p5LinkNode.getAttribute('p5:startIndex'),
						'value': p5LinkNode.textContent
					} )
				} else {
					if (DBG) console.warn("Not implemented p5:links/" + p5LinkNode.tagName)
				}
			}
		}
		else if (!fieldNode.children.length) {
			if (fieldNode.textContent) item[ fieldNode.localName ] = fieldNode.textContent
			else {
				var xlink = fieldNode.getAttribute('xlink:href')
				if (xlink) {
					if (!(fieldNode.tagName in item)) item[ fieldNode.tagName ] = []
					item[ fieldNode.tagName ].push( xlink )
				}
			}
		}
		else {
			if (!(fieldNode.tagName in item)) item[ fieldNode.tagName ] = []
			item[ fieldNode.tagName ].push( p5WFS_ParseFeatureFieldRecurse(fieldNode) )
		}
	}
	return item
}
function p5WFS_ParseFeatureMember(featureMember) { // @returns object from xml element <gml:featureMemeber>
	if (!featureMember) return null
	if (!featureMember.children.length) return null
	var featureNode = featureMember.children[0]
	if (!featureNode) return null
	if (!featureNode.children.length) return null
	return p5WFS_ParseFeatureFieldRecurse(featureNode)
}

/**
 * @usage

	p5WFS_GetFeature('p5_default_db:CRM_PROCES', {
		'featureID': 'CRM_PROCES.' + id,
	}).then(function (features) {
		// ...
	}).catch(function (e) {
		// ...
	})

 * @usage - expected one feature

	p5WFS_GetFeature('p5_default_db:CRM_PROCES', {
		'featureID': 'CRM_PROCES.' + id,
	}).then(function (features) {
		if (!features) throw "Nie odnaleziono rekordu id = " + id
		if (!features.length) throw "Nie odnaleziono rekordu id = " + id
		if (1 !== features.length) throw "Bład: API zwróciło za dużo rekordów"
		return features[0]
		console.log('fetched features', features)
	}).then(function (feature) {
		// ...
	}).catch(function (e) {
		// ...
	})

 * @usage - POST

	p5WFS_GetFeature('p5_default_db:CRM_PROCES', {
	 // 'Filter': '<ogc:PropertyIsEqualTo><ogc:PropertyName>' + "PARENT_ID" + '</ogc:PropertyName><ogc:Literal>' + parent_id + '</ogc:Literal></ogc:PropertyIsEqualTo>',
	 'sortBy': 'SORT_PRIO+A,ID',
	 'ogc:Filter': '<GetFeature xmlns="http://www.opengis.net/wfs/2.0"'+
		 ' xmlns:p5_default_db="' + BASE_WFS_URL + '/default_db"' +
		 ' xmlns:ogc="http://www.opengis.net/ogc"' +
		 ' xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"' +
		 ' service="WFS"' +
		 ' version="2.0.2"' +
		 ' xsi:schemaLocation="http://www.opengis.net/wfs/2.0 http://schemas.opengis.net/wfs/2.0/wfs.xsd">' +
		 '<ogc:Filter>' +
		 '<ogc:PropertyIsEqualTo><ogc:PropertyName>' + "PARENT_ID" + '</ogc:PropertyName><ogc:Literal>' + parent_id + '</ogc:Literal></ogc:PropertyIsEqualTo>' +
		 '</ogc:Filter>' +
		 '</GetFeature>'
	 }).then(function (features) {
 	...

 */
function p5WFS_GetFeature() {
	var xmlResponse = (new DOMParser()).parseFromString(responseText, "text/xml");
	if (!xmlResponse.children.length) throw "Missing response xml root element";
	var xmlRoot = xmlResponse.children[0];
	if ('html' === xmlRoot.localName) {
		console.log(xmlRoot) // html / body / parseerror / div
		throw "Parse xml error"
	}
	if ('FeatureCollection' !== xmlRoot.localName) {
		if ('ServiceExceptionReport' === xmlRoot.tagName) {
			if (xmlRoot.children[0] && xmlRoot.children[0].textContent) throw xmlRoot.children[0].textContent
			throw "WFS API Exception"
		}
		throw "Missing FeatureCollection as root element in wfs response"
	}
	var features = []
	for (var i = 0; i < xmlRoot.children.length; i++) {
		features.push(p5WFS_ParseFeatureMember(xmlRoot.children[i]))
	}
	return features.filter(function (item) { return !!item; })
}