//
// Parser.swift
//
// Copyright (c) 2014-2016 Marko Tadić <tadija@me.com> http://tadija.net
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//

import Foundation

/// Simple wrapper around `Foundation.XMLParser`.
internal class AEXMLParser: NSObject, XMLParserDelegate {
    
    // MARK: - Properties
    
    let document: AEXMLDocument
    let data: Data
    
    var currentParent: AEXMLElement?
    var currentElement: AEXMLElement?
    var currentValue = String()
    
    var parseError: Error?
    
    // MARK: - Lifecycle
    
    init(document: AEXMLDocument, data: Data) {
        self.document = document
        self.data = data
        currentParent = document
        
        super.init()
    }
    
    // MARK: - API
    
    func parse() throws {
        let parser = XMLParser(data: data)
        parser.delegate = self
        
        parser.shouldProcessNamespaces = document.options.parserSettings.shouldProcessNamespaces
        parser.shouldReportNamespacePrefixes = document.options.parserSettings.shouldReportNamespacePrefixes
        parser.shouldResolveExternalEntities = document.options.parserSettings.shouldResolveExternalEntities
        
        let success = parser.parse()
        
        if !success {
            guard let error = parseError else { throw AEXMLError.parsingFailed }
            throw error
        }
    }
    
    // MARK: - XMLParserDelegate
    
    @objc func parser(_ parser: XMLParser,
                      didStartElement elementName: String,
                      namespaceURI: String?,
                      qualifiedName qName: String?,
                      attributes attributeDict: [String : String])
    {
        currentValue = String()
        currentElement = currentParent?.addChild(name: elementName, attributes: attributeDict)
        currentParent = currentElement
    }
    
    @objc func parser(_ parser: XMLParser, foundCharacters string: String) {
        currentValue += string
        let newValue = currentValue.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
        currentElement?.value = newValue == String() ? nil : newValue
    }
    
    @objc func parser(_ parser: XMLParser,
                      didEndElement elementName: String,
                      namespaceURI: String?,
                      qualifiedName qName: String?)
    {
        currentParent = currentParent?.parent
        currentElement = nil
    }
    
    @objc func parser(_ parser: XMLParser, parseErrorOccurred parseError: Error) {
        self.parseError = parseError
    }
    
}