// This file is part of Germ <https://github.com/gemrest/germ>.
// Copyright (C) 2022-2025 Fuwn <contact@fuwn.me>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 3.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
// Copyright (C) 2022-2025 Fuwn <contact@fuwn.me>
// SPDX-License-Identifier: GPL-3.0-only

use {crate::ast::Node, std::fmt::Write};

pub fn convert(source: &[Node]) -> String {
  let mut html = String::new();

  // Since we have an AST tree of the Gemtext, it is very easy to convert from
  // this AST tree to an alternative markup format.
  for node in source {
    match node {
      Node::Text(text) => {
        let _ = write!(&mut html, "<p>{text}</p>");
      }
      Node::Link { to, text } => {
        let _ = write!(
          &mut html,
          "<a href=\"{}\">{}</a><br>",
          to,
          text.clone().unwrap_or_else(|| to.clone())
        );
      }
      Node::Heading { level, text } => {
        let _ = write!(
          &mut html,
          "<{}>{}</{0}>",
          match level {
            1 => "h1",
            2 => "h2",
            3 => "h3",
            _ => "p",
          },
          text
        );
      }
      Node::List(items) => {
        let _ = write!(
          &mut html,
          "<ul>{}</ul>",
          items
            .iter()
            .map(|i| format!("<li>{i}</li>"))
            .collect::<Vec<String>>()
            .join("\n")
        );
      }
      Node::Blockquote(text) => {
        let _ = write!(&mut html, "<blockquote>{text}</blockquote>");
      }
      Node::PreformattedText { text, .. } => {
        let _ = write!(&mut html, "<pre>{text}</pre>");
      }
      Node::Whitespace => {}
    }
  }

  html
}