// @require WFS_URL
if (!WFS_URL) throw "Missing WFS_URL"
var DBG = DBG || false
var httpFetch = window.fetch

// 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]
		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(typeName, query) { // @returns Promise
	var postData = null
	var link = WFS_URL + '?SERVICE=WFS&VERSION=1.0.0' +
		'&REQUEST=GetFeature' +
		'&TYPENAME=' + typeName +
		'&SRSNAME=EPSG:3003'
	;
	if ('WFS_URL' in query && query['WFS_URL'].length) {
		link = query['WFS_URL']
		link += ( (-1 !== query['WFS_URL'].indexOf('?')) ? '&' : '?' )
		link += 'SERVICE=WFS&VERSION=1.0.0'
		link += '&REQUEST=GetFeature'
		link += '&TYPENAME=' + typeName
		link += '&SRSNAME=EPSG:3003'
	}
	//	'&Filter=<ogc:Filter><ogc:Or><ogc:PropertyIsEqualTo><ogc:PropertyName>ID</ogc:PropertyName><ogc:Literal>' + id + '</ogc:Literal></ogc:PropertyIsEqualTo></ogc:Or></ogc:Filter>'
	var query = query || {}
	if ('featureID' in query) link += '&featureID=' + query['featureID']
	if ('Filter' in query && 'string' === typeof query['Filter']) {
		var ogcFilter = ('<ogc:Filter>' !== query['Filter'].substr(0, '<ogc:Filter>'.length))
			? '<ogc:Filter>' + query['Filter'] + '</ogc:Filter>'
			: query['Filter']
		;
		link += '&Filter=' + ogcFilter
	}
	if ('ogc:Filter' in query && 'string' === typeof query['ogc:Filter']) {
		var headerOgcFilter = '<GetFeature xmlns="http://www.opengis.net/wfs/2.0"' +
			' xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"' +
			' xmlns:ogc="http://www.opengis.net/ogc"' +
			' xmlns:wfs="http://www.opengis.net/wfs"' +
			' service="WFS"' +
			' version="2.0.2"' + '>'
		if ('<GetFeature' === query['ogc:Filter'].substr(0, '<GetFeature'.length)) {
			postData = query['ogc:Filter']
		} else if ('<ogc:Filter>' === query['ogc:Filter'].substr(0, '<ogc:Filter>'.length)) {
			postData = headerOgcFilter + '<wfs:Query>' + query['ogc:Filter'] + '</wfs:Query>' + '</GetFeature>'
		} else if ('<wfs:Query>' === query['ogc:Filter'].substr(0, '<wfs:Query>'.length)) {
			postData = headerOgcFilter + query['ogc:Filter'] + '</GetFeature>'
		} else {
			return Promise.reject(new Error('Wrong syntax ogc:Filter'))
		}
	}
	if ('graphql:query' in query && 'string' === typeof query['graphql:query']) { // TODO: http://graphql.org/learn/queries/
		link += '&outputFormat=json'
		postData = query['graphql:query']
	}
	if ('sortBy' in query) link += '&sortBy=' + query['sortBy']
	if ('maxFeatures' in query) link += '&maxFeatures=' + query['maxFeatures']
	if ('count' in query) link += '&count=' + query['count']
	if ('startIndex' in query) link += '&startIndex=' + query['startIndex']
	if ('primaryKey' in query) link += '&primaryKey=' + query['primaryKey']
	if ('resolveDepth' in query && !('resolve' in query)) return Promise.reject(new Error('ResolveDepth set but missing resolve="all"'))
	if ('resolve' in query) link += '&resolve=' + query['resolve']
	if ('resolveDepth' in query) link += '&resolveDepth=' + query['resolveDepth']
	if ('xlink' in query) link += '&xlink=' + query['xlink'] // NOTE: replace '#' to '/'
	if ('root' in query) link += '&root=' + query['root'] // NOTE: require admin perms (admin level 0)
	if ('backRefNS' in query && 'backRefPK' in query && 'backRefField' in query) {
		link += '&backRefNS=' + query['backRefNS']
		link += '&backRefPK=' + query['backRefPK']
		link += '&backRefField=' + query['backRefField']
	}
	if ('p5:next' in query) link = query['p5:next'];
	var method = (postData) ? 'POST' : 'GET'

	var wfsPromise = httpFetch(link, Object.assign({
		method: method,
		credentials: 'include',
	}, ('POST' === method)
		? {
			body: postData
		}
		: {}
	)).then(function (response) {
		return response.text()
	});
	return _p5WFS_GetFeaturePromise(wfsPromise);
}

function p5WFS_GetFeatureFromXml(url) {
	var wfsPromise = httpFetch(url, {
		method: 'GET',
		credentials: 'include',
	}).then(function (response) {
		return response.text()
	});
	return _p5WFS_GetFeaturePromise(wfsPromise);
}

function p5WFS_GetFeatureFromXmlString(xmlString) {
	var wfsPromise = new Promise(function (resolve, reject) {
		resolve(xmlString);
	});
	return _p5WFS_GetFeaturePromise(wfsPromise);
}

function _p5WFS_GetFeaturePromise(wfsPromise) {
	return wfsPromise.then(function (responseText) {
		return (new DOMParser()).parseFromString(responseText, "text/xml");
	}).then(function (xmlResponse) {
		if (!xmlResponse.children.length) throw "Missing response xml root element"
		return xmlResponse.children[0]
	}).then(function (xmlRoot) {
		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; })
	})
}

module.exports = {
	p5WFS_ParseFeatureMember: p5WFS_ParseFeatureMember,
	p5WFS_ParseFeatureFieldRecurse: p5WFS_ParseFeatureFieldRecurse,
	p5WFS_GetFeature: p5WFS_GetFeature,
	p5WFS_GetFeatureFromXml: p5WFS_GetFeatureFromXml,
	p5WFS_GetFeatureFromXmlString: p5WFS_GetFeatureFromXmlString,
}