///|
pub(all) struct HnItem {
  id : Int
  by : String?
  time : Int?
  text : String?
  deleted : Bool?
  dead : Bool?
  kids : Array[Int]?
  url : String?
  score : Int?
  title : String?
  descendants : Int?
} derive(FromJson, ToJson, @debug.Debug)

///|
pub(all) struct CommentBrief {
  id : Int
  by : String
  text : String
  replies : Int
} derive(ToJson, @debug.Debug)

///|
pub(all) struct StoryBrief {
  id : Int
  title : String
  url : String
  score : Int
  comments : Int
  hot_comments : Array[CommentBrief]
} derive(ToJson, @debug.Debug)

///|
pub(all) struct BriefStats {
  stories : Int
  hot_comments : Int
  total_score : Int
  total_discussion_comments : Int
} derive(ToJson, @debug.Debug)

///|
pub fn HnItem::is_visible(self : HnItem) -> Bool {
  self.deleted != Some(true) && self.dead != Some(true)
}

///|
pub fn HnItem::reply_count(self : HnItem) -> Int {
  match self.kids {
    Some(kids) => kids.length()
    None => 0
  }
}

///|
pub fn HnItem::to_comment_brief(self : HnItem) -> CommentBrief {
  {
    id: self.id,
    by: self.by.unwrap_or("unknown"),
    text: clean_hn_text(self.text.unwrap_or("")),
    replies: self.reply_count(),
  }
}

///|
pub fn HnItem::to_story_brief(
  self : HnItem,
  hot_comments : Array[CommentBrief],
) -> StoryBrief {
  {
    id: self.id,
    title: self.title.unwrap_or("(untitled)"),
    url: self.url.unwrap_or("https://news.ycombinator.com/item?id=\{self.id}"),
    score: self.score.unwrap_or(0),
    comments: self.descendants.unwrap_or(0),
    hot_comments,
  }
}

///|
pub fn clean_hn_text(text : String) -> String {
  let normalized = text
    .replace_all(old="
", new="\n")
    .replace_all(old="
", new="\n")
    .replace_all(old="
", new="\n")
  let without_tags = strip_html_tags(normalized)
  without_tags
  .replace_all(old=""", new="\"")
  .replace_all(old="'", new="'")
  .replace_all(old="/", new="/")
  .replace_all(old="&", new="&")
  .replace_all(old="<", new="<")
  .replace_all(old=">", new=">")
  .replace_all(old="\n ", new="\n")
  .replace_all(old="  ", new=" ")
  .replace_all(old="  ", new=" ")
  .replace_all(old="\n\n", new="\n")
  .trim()
  .to_owned()
}

///|
fn strip_html_tags(text : String) -> String {
  let out = StringBuilder::new(size_hint=text.length())
  let mut in_tag = false
  for ch in text {
    if ch == '<' {
      in_tag = true
    } else if ch == '>' {
      in_tag = false
      out.write_char(' ')
    } else if !in_tag {
      out.write_char(ch)
    }
  }
  out.to_string()
}

///|
pub fn summary_prompt(stories : ArrayView[StoryBrief], lang : String) -> String {
  let out = StringBuilder::new()
  out.write_string(
    "Summarize these Hacker News stories and ranked comments in \{lang}. ",
  )
  out.write_string(
    "Return concise sections for themes, why it matters, hot comment consensus, disagreements, and takeaways.\n\n",
  )
  for index, story in stories {
    out.write_string(
      "Story \{index + 1}: \{story.title}\nscore=\{story.score}, comments=\{story.comments}\nurl=\{story.url}\n",
    )
    for comment_index, comment in story.hot_comments {
      out.write_string(
        "- Comment \{comment_index + 1} by \{comment.by}, replies=\{comment.replies}: \{comment.text}\n",
      )
    }
    out.write_string("\n")
  }
  out.to_string()
}

///|
pub fn stats(stories : ArrayView[StoryBrief]) -> BriefStats {
  let mut hot_comments = 0
  let mut total_score = 0
  let mut total_discussion_comments = 0
  for story in stories {
    hot_comments += story.hot_comments.length()
    total_score += story.score
    total_discussion_comments += story.comments
  }
  {
    stories: stories.length(),
    hot_comments,
    total_score,
    total_discussion_comments,
  }
}

///|
pub fn render_markdown(
  stories : ArrayView[StoryBrief],
  summary : String,
  model_label~ : String,
  show_context? : Bool = false,
) -> String {
  let out = StringBuilder::new()
  out.write_string("# HN Brief\n\n")
  out.write_string("Source: Hacker News API\n\n")
  let stat = stats(stories)
  out.write_string("## Stats\n\n")
  out.write_string("- Stories fetched: \{stat.stories}\n")
  out.write_string("- Ranked comments fetched: \{stat.hot_comments}\n")
  out.write_string("- Total HN score: \{stat.total_score}\n")
  out.write_string(
    "- Total discussion comments: \{stat.total_discussion_comments}\n\n",
  )
  out.write_string("## Summary (\{model_label})\n\n")
  out.write_string(summary)
  if !summary.has_suffix("\n") {
    out.write_string("\n")
  }
  if show_context {
    out.write_string("\n## Top Stories and Hot Comments\n\n")
    for index, story in stories {
      out.write_string(
        "### \{index + 1}. \{story.title}\n\n- Score: \{story.score}\n- Comments: \{story.comments}\n- URL: \{story.url}\n\n",
      )
      if story.hot_comments.is_empty() {
        out.write_string("No visible ranked comments fetched.\n\n")
      } else {
        out.write_string("Hot comments:\n")
        for comment in story.hot_comments {
          out.write_string(
            "- \{comment.by} (\{comment.replies} replies): \{comment.text}\n",
          )
        }
        out.write_string("\n")
      }
    }
  }
  out.to_string()
}