//
//  ArticleInfo.swift
//  Hair Society Go
//
//  Created by Joshua Srery on 1/13/21.
//  Code provided by OOPer on Apple Developer Forums
//

import Foundation

struct ArticleInfo: Identifiable, Codable {
    var id: String = ""
    var title: String = ""
    var date: Date?
    var author: String = ""
    var img: URL?
    var content: String = ""
}

class ArticlesInfo: ObservableObject {
    @Published var articles: [ArticleInfo] = []
}


class ArticlesParser: XMLParser {
    
    var dateTimeZone = TimeZone(abbreviation: "GMT-6")
    lazy var dateFormater: DateFormatter = {
        let df = DateFormatter()
        df.locale = Locale(identifier: "en_US_POSIX")
        df.dateFormat = "MMM dd, yyyy"
        df.timeZone = dateTimeZone
        return df
    }()
    
    private var textBuffer: String = ""
    private var nextArticle: ArticleInfo? = nil
    override init(data: Data) {
        super.init(data: data)
        self.delegate = self
    }
}
extension ArticlesParser: XMLParserDelegate {
    // Called when opening tag (`<elementName>`) is found
    func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:]) {
        switch elementName {
        case "posts":
            nextArticle = ArticleInfo()
        case "title":
            textBuffer = ""
        case "date":
            textBuffer = ""
        case "author":
            textBuffer = ""
        case "img":
            textBuffer = ""
        case "content":
            textBuffer = ""
        default:
            print("Ignoring \(elementName)")
            break
        }
    }
    
    // Called when closing tag (`</elementName>`) is found
    func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
        switch elementName {
        case "posts":
            if let article = nextArticle {
                articles.append(article) // Cannot find 'articles' in scope
            }
        case "title":
            nextArticle?.title = textBuffer
        case "date":
            print("date: \(textBuffer)")
            nextArticle?.date = dateFormater.date(from: textBuffer)
        case "author":
            nextArticle?.author = textBuffer
        case "img":
            print("img: \(textBuffer)")
            nextArticle?.img = URL(string: textBuffer)
        case "content":
            nextArticle?.content = textBuffer
        default:
            print("Ignoring \(elementName)")
            break
        }
    }
    
    // Called when a character sequence is found
    // This may be called multiple times in a single element
    func parser(_ parser: XMLParser, foundCharacters string: String) {
        textBuffer += string
    }
    
    // Called when a CDATA block is found
    func parser(_ parser: XMLParser, foundCDATA CDATABlock: Data) {
        guard let string = String(data: CDATABlock, encoding: .utf8) else {
            print("CDATA contains non-textual data, ignored")
            return
        }
        textBuffer += string
    }
    
    // For debugging
    func parser(_ parser: XMLParser, parseErrorOccurred parseError: Error) {
        print(parseError)
        print("on:", parser.lineNumber, "at:", parser.columnNumber)
    }
}

extension ArticlesInfo {
    var dataUrl: URL {
        FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
            .appendingPathComponent("THS.xml")
    }
    
    func saveCards() {
        do {
            //Convert Array of `CardInfo` to `Data`
            let data = try JSONEncoder().encode(dataUrl)
            //Write `Data` to a file specified by URL
            try data.write(to: dataUrl, options: .atomic)
        } catch {
            print(error)
        }
    }
    
    func loadArticles() {
        do {
            if FileManager.default.fileExists(atPath: dataUrl.path) {
                return
            }
            //Read `Data` from a file specified by URL
            let data = try Data(contentsOf: dataUrl)
            //Parse Available Articles
            let articles = try JSONDecoder().decode([ArticleInfo].self, from: data)
            self.articles = articles
        } catch {
            print(error)
        }
    }
}