//
//  GeminiMarkdownRenderer.swift
//  GeminiRenderer
//
//  Created by Shadowfacts on 10/1/21.
//

import Foundation
import HTMLEntities

public class GeminiMarkdownRenderer {
    
    public init() {
    }
    
    public func renderDocumentToMarkdown(_ doc: Document) -> String {
        var str = ""
        
        var inPreformatting = false
        var inList = false
        
        for line in doc.lines {
            if inList && !line.isListItem {
                str += "\n"
                inList = false
            }
            
            switch line {
            case let .text(text):
                if !text.trimmingCharacters(in: .whitespaces).isEmpty {
                    str += text.htmlEscape()
                    str += "\n\n"
                }
                
            case let .link(url, text: maybeText):
                let text = maybeText ?? url.absoluteString
                // todo: do ] in the text need to be escaped?
                str += "[\(text.htmlEscape())](\(url))"
                str += "\n\n"
                
            case let .preformattedToggle(alt: alt):
                inPreformatting = !inPreformatting
                if inPreformatting {
                    str += "```"
                    if let alt = alt {
                        str += alt
                    }
                    str += "\n"
                } else {
                    str += "```"
                    str += "\n\n"
                }
                
            case let .preformattedText(text):
                str += text
                str += "\n"
                
            case let .heading(text, level: level):
                str += String(repeating: "#", count: level.rawValue)
                str += " "
                str += text.htmlEscape()
                str += "\n\n"
                
            case let .unorderedListItem(text):
                if !inList {
                    inList = true
                }
                str += "* \(text.htmlEscape())"
                str += "\n"
                
            case let .quote(text):
                str += "> "
                str += text.htmlEscape()
                str += "\n\n"
            }
        }
        
        return str
    }
    
}