//
//  HTMLParser.swift
//
//
//  Created by Isaac Paul on 7/31/24.
//

public class HTMLText : HTMLNode, IFlowContent {
    
    public var content: String
    
    public init(content: String) {
        self.content = content
        try! super.init( expectedAttributes: [:])
    }

    override public func toString(_ depth:Int = 0, spacingStrat:SpacingStrat = .tabs) -> (Int, String) {
        return (depth, content)
    }
}

public class XMLText : XMLNode {
    
    public var content: String
    
    public init(content: String) {
        self.content = content
        super.init()
    }
}

extension XMLParser {
    public func readObjects(endTag:String? = nil, validTags:[String]? = nil) throws -> [HTMLNode] {
        var allItems:[HTMLNode] = []
        while let obj = try self.readObject(endTag: endTag, validTags: validTags, xmlToHtmlMapper) {
            allItems.append(obj)
        }
        return allItems
    }
    
    public func readObject(endTag:String? = nil, validTags:[String]? = nil, _ mapper:(_ name:String, _ attributes:[String:String], _ parser:XMLParser?)  throws -> HTMLNode) throws -> HTMLNode? {
        let tag = try readToken()
        switch (tag) {
            case let .data(unicode):
                var result = ""
                result.unicodeScalars.append(contentsOf: unicode)
                return HTMLText(content: result)
            case .instruction:
                throw AppError("Unexpected Instruction")
            case let .tag_empty(name, attributes):
                if let validTags = validTags {
                    if (validTags.firstIndex(of: name) == nil) {
                        throw AppError("Invalid tag: \(name) for element \(endTag ?? "root")")
                    }
                }
                let mapped = try mapper(name, attributes, nil)
                return mapped
            case let .tag_end(name):
                if let tag = endTag,
                    name != tag {
                    throw AppError("Unexpected end tag: \(name) for element \(tag)")
                }
                return nil
            case let .tag_start(name, attributes):
                if let validTags = validTags {
                    if (validTags.firstIndex(of: name) == nil) {
                        throw AppError("Invalid tag: \(name) for element \(endTag ?? "root")")
                    }
                }
                return try mapper(name, attributes, self)
            case .none:
                if (endTag == nil) {
                    return nil
                } else {
                    throw AppError("Reached end of document before closing tag: \(endTag ?? "root")")
                }
        }
    }
    
    public func readObjectXml(endTag:String? = nil, validTags:[String]? = nil) throws -> XMLNode? {
        let tag = try readToken()
        switch (tag) {
            case let .data(unicode):
                var result = ""
                result.unicodeScalars.append(contentsOf: unicode)
                return XMLText(content: result)
            case .instruction:
                throw AppError("Unexpected Instruction")
            case let .tag_empty(name, attributes):
                if let validTags = validTags {
                    if (validTags.firstIndex(of: name) == nil) {
                        throw AppError("Invalid tag: \(name) for element  \(endTag ?? "root")")
                    }
                }
                return try GenericXMLNode(name, attributes, nil)
            case let .tag_end(name):
                if let tag = endTag,
                    name != tag {
                    throw AppError("Unexpected end tag: \(name) for element \(tag)")
                }
                return nil
            case let .tag_start(name, attributes):
                if let validTags = validTags {
                    if (validTags.firstIndex(of: name) == nil) {
                        throw AppError("Invalid tag: \(name) for element \(endTag ?? "root")")
                    }
                }
                return try GenericXMLNode(name, attributes, self)
            case .none:
                if (endTag == nil) {
                    return nil
                } else {
                    throw AppError("Reached end of document before closing tag: \(endTag ?? "root")")
                }
        }
    }
    
    public func readDataAsString(endTag:String) throws -> String? {
        let tag = try readToken()
        switch (tag) {
            case let .data(unicode):
                var result = ""
                result.unicodeScalars.append(contentsOf: unicode)
                return result
            case .instruction:
                throw AppError("Unexpected Instruction")
            case let .tag_empty(name, attributes):
                throw AppError("Unexpected empty tag: \(name)")
            case let .tag_end(name):
                if (name != endTag) {
                    throw AppError("Unexpected end tag: \(name)")
                }
                return nil
            case let .tag_start(name, attributes):
                throw AppError("Unexpected tag start: \(name)")
            case .none:
                throw AppError("Reached end of document before closing tag: \(endTag)")
        }
    }
}