import { NOSTR_URI_INLINE_REGEX } from '@/lib/content-patterns'
import { isImage, isVideo, isAudio } from '@/lib/url'
import { URL_REGEX, YOUTUBE_URL_REGEX } from '@/constants'

/**
 * Check if a URL is a YouTube URL
 */
function isYouTubeUrl(url: string): boolean {
  // Create a new regex instance to avoid state issues with global regex
  const flags = YOUTUBE_URL_REGEX.flags.replace('g', '')
  const regex = new RegExp(YOUTUBE_URL_REGEX.source, flags)
  return regex.test(url)
}

/**
 * Preprocess content to convert raw media URLs and hyperlinks to markdown syntax
 * - Images: https://example.com/image.png -> ![](https://example.com/image.png)
 * - Videos: https://example.com/video.mp4 -> ![](https://example.com/video.mp4)
 * - Audio: https://example.com/audio.mp3 -> ![](https://example.com/audio.mp3)
 * - Hyperlinks: https://example.com/page -> [https://example.com/page](https://example.com/page)
 */
export function preprocessMarkdownMediaLinks(content: string): string {
  let processed = content
  
  // First, handle angle bracket URLs: <https://example.com> -> https://example.com
  // These should be converted to plain URLs so they can be processed by the URL regex
  const angleBracketUrlRegex = /<((?:https?|ftp):\/\/[^\s<>"']+)>/g
  processed = processed.replace(angleBracketUrlRegex, (_match, url) => {
    // Just remove the angle brackets, leaving the URL for the main URL processor to handle
    return url
  })
  
  // Find all URLs but process them in reverse order to preserve indices
  const allMatches: Array<{ url: string; index: number }> = []
  
  let match
  const regex = new RegExp(URL_REGEX.source, URL_REGEX.flags)
  while ((match = regex.exec(processed)) !== null) {
    const index = match.index
    const url = match[0]
    const before = processed.substring(Math.max(0, index - 20), index)
    
    // Check if this URL is already part of markdown syntax
    // Skip if preceded by: [text](url, ![text](url, or ](url
    if (before.match(/\[[^\]]*$/) || before.match(/\]\([^)]*$/) || before.match(/!\[[^\]]*$/)) {
      continue
    }
    
    allMatches.push({ url, index })
  }
  
  // Process in reverse order to preserve indices
  for (let i = allMatches.length - 1; i >= 0; i--) {
    const { url, index } = allMatches[i]
    
    // Check if URL is in code block
    const beforeUrl = processed.substring(0, index)
    const backticksCount = (beforeUrl.match(/```/g) || []).length
    if (backticksCount % 2 === 1) {
      continue // In code block
    }
    
    // Check if URL is in inline code
    const lastBacktick = beforeUrl.lastIndexOf('`')
    if (lastBacktick !== -1) {
      const afterUrl = processed.substring(index + url.length)
      const nextBacktick = afterUrl.indexOf('`')
      if (nextBacktick !== -1) {
        const codeBefore = beforeUrl.substring(lastBacktick + 1)
        const codeAfter = afterUrl.substring(0, nextBacktick)
        // If no newlines between backticks, it's inline code
        if (!codeBefore.includes('\n') && !codeAfter.includes('\n')) {
          continue
        }
      }
    }
    
    // Check if it's a media URL or YouTube URL
    const isImageUrl = isImage(url)
    const isVideoUrl = isVideo(url)
    const isAudioUrl = isAudio(url)
    const isYouTube = isYouTubeUrl(url)
    
    // Skip YouTube URLs - they should be left as plain text so they can be detected and rendered as YouTube embeds
    if (isYouTube) {
      continue
    }
    
    let replacement: string
    if (isImageUrl || isVideoUrl || isAudioUrl) {
      // Media URLs: convert to ![](url)
      replacement = `![](${url})`
    } else {
      // Regular hyperlinks: convert to [url](url) format
      replacement = `[${url}](${url})`
    }
    
    // Replace the URL
    processed = processed.substring(0, index) + replacement + processed.substring(index + url.length)
  }
  
  return processed
}

/**
 * Preprocess content to convert raw media URLs and hyperlinks to AsciiDoc syntax
 * - Images: https://example.com/image.png -> image::https://example.com/image.png[]
 * - Videos: https://example.com/video.mp4 -> video::https://example.com/video.mp4[]
 * - Audio: https://example.com/audio.mp3 -> audio::https://example.com/audio.mp3[]
 * - Hyperlinks: https://example.com/page -> https://example.com/page[link text]
 * - Wikilinks: [[link]] or [[link|display]] -> +++WIKILINK:link|display+++ (passthrough for post-processing)
 */
export function preprocessAsciidocMediaLinks(content: string): string {
  let processed = content
  
  // Note: Wikilinks are now processed in AsciidocArticle.tsx BEFORE this function is called
  // to prevent AsciiDoc from converting them to regular links. We skip wikilink processing here.
  
  // Skip any remaining wikilinks (they should already be processed, but safety check)
  // Check for passthrough markers to avoid double-processing
  if (processed.includes('BOOKSTR_START:') || processed.includes('WIKILINK:')) {
    // Wikilinks already processed, skip
  } else {
    // Fallback: protect bookstr wikilinks if they weren't processed yet
    processed = processed.replace(/\[\[book::([^\]]+)\]\]/g, (_match, bookContent) => {
      const cleanContent = bookContent.trim()
      return `+++BOOKSTR_MARKER:${cleanContent}:BOOKSTR_END+++`
    })
    
    // Fallback: protect regular wikilinks if they weren't processed yet
    processed = processed.replace(/\[\[([^\]]+)\]\]/g, (_match, linkContent) => {
      // Skip if this was already processed as a bookstr wikilink
      if (linkContent.startsWith('book::')) {
        return _match
      }
      return `+++WIKILINK:${linkContent}+++`
    })
  }
  
  // Find all URLs but process them in reverse order to preserve indices
  const allMatches: Array<{ url: string; index: number }> = []
  
  let match
  const regex = new RegExp(URL_REGEX.source, URL_REGEX.flags)
  while ((match = regex.exec(content)) !== null) {
    const index = match.index
    const url = match[0]
    const urlEnd = index + url.length
    
    // Skip URLs that are inside wikilinks (already processed as passthrough markers)
    // Check if URL is inside a passthrough marker
    const beforeUrl = content.substring(Math.max(0, index - 100), index)
    const afterUrl = content.substring(urlEnd, Math.min(content.length, urlEnd + 100))
    if (beforeUrl.includes('BOOKSTR_START:') || beforeUrl.includes('WIKILINK:') || 
        afterUrl.includes(':BOOKSTR_END') || afterUrl.includes('+++')) {
      continue
    }
    
    // Check if this URL is part of an AsciiDoc link format url[text]
    // If URL is immediately followed by [text], it's already an AsciiDoc link - skip it
    const contextAfter = content.substring(urlEnd, Math.min(content.length, urlEnd + 50))
    if (contextAfter.match(/^\s*\[[^\]]+\]/)) {
      continue
    }
    
    const before = content.substring(Math.max(0, index - 30), index)
    
    // Check if this URL is already part of AsciiDoc syntax
    // Skip if preceded by: image::, video::, audio::, or link:
    if (before.match(/image::\s*$/) || 
        before.match(/video::\s*$/) || 
        before.match(/audio::\s*$/) ||
        before.match(/link:\S+\[/) ||
        before.match(/https?:\/\/[^\s]*\[/)) {
      continue
    }
    
    allMatches.push({ url, index })
  }
  
  // Process in reverse order to preserve indices
  for (let i = allMatches.length - 1; i >= 0; i--) {
    const { url, index } = allMatches[i]
    
    // Check if URL is in code block
    const beforeUrl = content.substring(0, index)
    const codeBlockCount = (beforeUrl.match(/----/g) || []).length
    if (codeBlockCount % 2 === 1) {
      continue // In code block
    }
    
    // Check if it's a media URL or YouTube URL
    const isImageUrl = isImage(url)
    const isVideoUrl = isVideo(url)
    const isAudioUrl = isAudio(url)
    const isYouTube = isYouTubeUrl(url)
    
    let replacement: string
    if (isImageUrl) {
      // Images: convert to image::url[]
      replacement = `image::${url}[]`
    } else if (isVideoUrl) {
      // Videos: convert to video::url[]
      replacement = `video::${url}[]`
    } else if (isAudioUrl) {
      // Audio: convert to audio::url[]
      replacement = `audio::${url}[]`
    } else if (isYouTube) {
      // YouTube URLs: convert to link:url[url] (will be handled in post-processing)
      // This allows AsciiDoc to process it as a link, then we'll replace it with YouTube player
      replacement = `link:${url}[${url}]`
    } else {
      // Regular hyperlinks: convert to link:url[url]
      replacement = `link:${url}[${url}]`
    }
    
    // Replace the URL
    processed = processed.substring(0, index) + replacement + processed.substring(index + url.length)
  }
  
  return processed
}

/**
 * Post-process content to convert nostr: links and hashtags
 * This should be applied AFTER markup processing
 */
export function postProcessNostrLinks(content: string): string {
  let processed = content
  
  // Convert nostr: prefixed links to embedded format
  // nostr:npub1... -> [nostr:npub1...]
  // nostr:note1... -> [nostr:note1...]
  // etc.
  const nostrRegex = new RegExp(NOSTR_URI_INLINE_REGEX.source, NOSTR_URI_INLINE_REGEX.flags)
  processed = processed.replace(nostrRegex, (match) => {
    // Already in a link? Don't double-wrap
    // Check if it's already in markdown link syntax [text](nostr:...)
    // or AsciiDoc link syntax link:nostr:...[text]
    return match // Keep as is for now, will be processed by the parser
  })
  
  // Convert hashtags to links
  // #tag -> link:/notes?t=tag[#tag] (for AsciiDoc) or [#tag](/notes?t=tag) (for Markdown)
  // But only if not already in a link
  // We'll handle this in the rendering phase to avoid breaking markup
  
  return processed
}