Add the library

1 files changed, 274 insertions, 0 deletions

diff --git a/src/html_renderer.rs b/src/html_renderer.rs
new file mode 100644
index 0000000..e513533
--- /dev/null
+++ b/src/html_renderer.rs
@@ -0,0 +1,274 @@
+use crate::gemini_parser::GeminiLine;
+
+/// Renders HTML from a vector of `GeminiLine` elements.
+///
+/// # Arguments
+/// * `lines` - Vector of `GeminiLine` elements to render
+///
+/// # Returns
+/// A String containing the rendered HTML.
+///
+/// # Examples
+/// ```
+/// use std::fs::read_to_string;
+/// use gema_texto::gemini_parser::parse;
+/// use gema_texto::html_renderer::render_html;
+///
+/// let gemini_source = "\
+/// # Hello
+/// This is some gemini text!
+/// => https://test Go to the test page.
+/// ";
+///
+/// let gemini_lines = parse(&gemini_source);
+/// let html_source = render_html(&gemini_lines);
+/// println!("{html_source}");
+/// ```
+#[must_use]
+pub fn render_html(lines: &[GeminiLine]) -> String {
+    let mut heading_stack = Vec::new();
+    let mut last_line: Option<&GeminiLine> = None;
+    let mut result = String::new();
+
+    for line in lines {
+        result.push_str(&line_preamble(line, last_line, &mut heading_stack));
+        result.push_str(&line_content(line));
+        result.push('\n');
+        last_line = Some(line);
+    }
+
+    result.push_str(&finalize_html(&heading_stack, last_line));
+    result
+}
+
+fn line_preamble(
+    line: &GeminiLine,
+    last_line: Option<&GeminiLine>,
+    heading_stack: &mut Vec<u8>,
+) -> String {
+    let mut html = String::new();
+
+    if let Some(last_line) = last_line {
+        match last_line {
+            GeminiLine::ListItem(_) => match line {
+                GeminiLine::ListItem(_) => {}
+                _ => html.push_str("</ul>\n"),
+            },
+            GeminiLine::Quote(_) => match line {
+                GeminiLine::Quote(_) => {}
+                _ => html.push_str("</blockquote>\n"),
+            },
+            _ => {}
+        }
+    }
+
+    match line {
+        GeminiLine::Heading(level, _) => {
+            while let Some(open_heading) = heading_stack.pop() {
+                // You just encountered a more important heading.
+                // Put it back. Desist.
+                if open_heading < *level {
+                    heading_stack.push(open_heading);
+                    break;
+                }
+
+                html.push_str("</section>\n");
+
+                if open_heading == *level {
+                    break;
+                }
+            }
+            heading_stack.push(*level);
+            html.push_str(&format!("<section class=\"h{level}\">\n"));
+        }
+        GeminiLine::ListItem(_) => match last_line {
+            Some(GeminiLine::ListItem(_)) => {}
+            _ => html.push_str("<ul>\n"),
+        },
+        GeminiLine::Quote(_) => match last_line {
+            Some(GeminiLine::Quote(_)) => {}
+            _ => html.push_str("<blockquote>\n"),
+        },
+        _ => {}
+    }
+
+    html
+}
+
+fn line_content(line: &GeminiLine) -> String {
+    match line {
+        GeminiLine::Text(content, false) => format!("<p>{content}</p>"),
+        GeminiLine::Link(url, text) => {
+            let display = if text.is_empty() { url } else { text };
+            format!("<p class=\"a\"><a href=\"{url}\">{display}</a></p>")
+        }
+        GeminiLine::Heading(level, content) => format!("<h{level}>{content}</h{level}>"),
+        GeminiLine::ListItem(content) => format!("<li>{content}</li>"),
+        GeminiLine::PreformattedToggle(true, alt_text) => {
+            format!("<pre aria-label=\"{alt_text}\">")
+        }
+        GeminiLine::PreformattedToggle(false, _) => "</pre>".to_string(),
+        GeminiLine::Text(content, true) | GeminiLine::Quote(content) => content.to_string(),
+    }
+}
+
+fn finalize_html(heading_stack: &[u8], last_line: Option<&GeminiLine>) -> String {
+    let mut html = String::new();
+
+    match last_line {
+        Some(GeminiLine::ListItem(_)) => html.push_str("</ul>\n"),
+        Some(GeminiLine::Quote(_)) => html.push_str("</blockquote>\n"),
+        _ => {}
+    }
+
+    for _ in heading_stack {
+        html.push_str("</section>\n");
+    }
+
+    html
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_simple_text() {
+        let input = vec![GeminiLine::Text("Hello world".to_string(), false)];
+        assert_eq!(render_html(&input), "<p>Hello world</p>\n");
+    }
+
+    #[test]
+    fn test_heading_nesting() {
+        let input = vec![
+            GeminiLine::Heading(1, "Top".to_string()),
+            GeminiLine::Heading(2, "Sub".to_string()),
+            GeminiLine::Heading(3, "SubSub".to_string()),
+            GeminiLine::Heading(2, "Another Sub".to_string()),
+        ];
+        assert_eq!(
+            render_html(&input),
+            "<section class=\"h1\">\n\
+             <h1>Top</h1>\n\
+             <section class=\"h2\">\n\
+             <h2>Sub</h2>\n\
+             <section class=\"h3\">\n\
+             <h3>SubSub</h3>\n\
+             </section>\n\
+             </section>\n\
+             <section class=\"h2\">\n\
+             <h2>Another Sub</h2>\n\
+             </section>\n\
+             </section>\n"
+        );
+    }
+
+    #[test]
+    fn test_list_transitions() {
+        let input = vec![
+            GeminiLine::ListItem("First".to_string()),
+            GeminiLine::ListItem("Second".to_string()),
+            GeminiLine::Text("Break".to_string(), false),
+            GeminiLine::ListItem("New list".to_string()),
+        ];
+        assert_eq!(
+            render_html(&input),
+            "<ul>\n\
+             <li>First</li>\n\
+             <li>Second</li>\n\
+             </ul>\n\
+             <p>Break</p>\n\
+             <ul>\n\
+             <li>New list</li>\n\
+             </ul>\n"
+        );
+    }
+
+    #[test]
+    fn test_quote_transitions() {
+        let input = vec![
+            GeminiLine::Quote("First quote".to_string()),
+            GeminiLine::Quote("Still quoting".to_string()),
+            GeminiLine::Text("Normal text".to_string(), false),
+            GeminiLine::Quote("New quote".to_string()),
+        ];
+        assert_eq!(
+            render_html(&input),
+            "<blockquote>\n\
+             First quote\n\
+             Still quoting\n\
+             </blockquote>\n\
+             <p>Normal text</p>\n\
+             <blockquote>\n\
+             New quote\n\
+             </blockquote>\n"
+        );
+    }
+
+    #[test]
+    fn test_preformatted() {
+        let input = vec![
+            GeminiLine::PreformattedToggle(true, "code".to_string()),
+            GeminiLine::Text("let x = 42;".to_string(), true),
+            GeminiLine::PreformattedToggle(false, String::new()),
+        ];
+        assert_eq!(
+            render_html(&input),
+            "<pre aria-label=\"code\">\n\
+             let x = 42;\n\
+             </pre>\n"
+        );
+    }
+
+    #[test]
+    fn test_links() {
+        let input = vec![
+            GeminiLine::Link("https://example.com".to_string(), "Example".to_string()),
+            GeminiLine::Link("https://rust-lang.org".to_string(), String::new()),
+        ];
+        assert_eq!(
+            render_html(&input),
+            "<p class=\"a\"><a href=\"https://example.com\">Example</a></p>\n\
+             <p class=\"a\"><a href=\"https://rust-lang.org\">https://rust-lang.org</a></p>\n"
+        );
+    }
+
+    #[test]
+    fn test_complex_nesting() {
+        let input = vec![
+            GeminiLine::Heading(1, "Title".to_string()),
+            GeminiLine::Text("Intro".to_string(), false),
+            GeminiLine::Heading(2, "Section".to_string()),
+            GeminiLine::ListItem("Point 1".to_string()),
+            GeminiLine::ListItem("Point 2".to_string()),
+            GeminiLine::Quote("Important quote".to_string()),
+            GeminiLine::Heading(2, "Another Section".to_string()),
+        ];
+        assert_eq!(
+            render_html(&input),
+            "<section class=\"h1\">\n\
+             <h1>Title</h1>\n\
+             <p>Intro</p>\n\
+             <section class=\"h2\">\n\
+             <h2>Section</h2>\n\
+             <ul>\n\
+             <li>Point 1</li>\n\
+             <li>Point 2</li>\n\
+             </ul>\n\
+             <blockquote>\n\
+             Important quote\n\
+             </blockquote>\n\
+             </section>\n\
+             <section class=\"h2\">\n\
+             <h2>Another Section</h2>\n\
+             </section>\n\
+             </section>\n"
+        );
+    }
+
+    #[test]
+    fn test_empty_input() {
+        let input = Vec::new();
+        assert_eq!(render_html(&input), "");
+    }
+}