// TAKEN FROM PAGE. Need to move to a common source.
    pub fn parse(source: &str) -> String {

    let lines = source.split("\n");
    let mut is_preformatted = false;

    let mut block_label: Option<String> = None;
    let mut html: String = "".to_owned();
    let mut current_line_type: Option<LineType> = None;

    let mut heading_stack: Vec<u8> = Vec::new();
    for line in lines {
        let mut line_type = LineType::Blank;
        if line.char_indices().count() > 2 {
            let mut end = line.len();
            if line.char_indices().count() > 3 {
                end = line.char_indices().map(|(i, _)| i).nth(3).unwrap();
            }
            line_type = identify_line(&line[..end], is_preformatted);
        }
        match line_type {
            LineType::PreformattedToggle => {
                is_preformatted = !is_preformatted;
                if is_preformatted && line.char_indices().count() > 3 {
                    block_label = Some(get_partial_line_content(&line_type, line));
                } else {
                    block_label = None;
                }
            },
            _ => {
                // Close previous block if needed
                if let Some(line) = &current_line_type {
                    if line != &line_type && is_block(line) {
                        html.push_str(get_line_closer(line));
                    }
                }

                // Blocks
                if is_block(&line_type) {
                    if let Some(line) = &current_line_type {
                        if line != &line_type  {
                            html.push_str(&get_line_opener(&line_type, block_label.as_ref()));
                        }
                    } else {
                        html.push_str(&get_line_opener(&line_type, None));
                    }

                    let line_content = get_partial_line_content(&line_type, line);
                    html.push_str(&line_content);
                } else {
                    html.push_str(&get_heading_wrapper(&mut heading_stack, &line_type));
                    html.push_str(&get_full_line_content(&line_type, line));
                }
                current_line_type = Some(line_type);
            },
        }
    }
    if let Some(line) = &current_line_type {
        if is_block(line) {
            html.push_str(get_line_closer(line));
        }
    }
    html.push_str(&close_heading_wrapper(&mut heading_stack));
    html
}

fn is_block(line_type: &LineType) -> bool {
    return match line_type {
        LineType::PreformattedText | LineType::ListItem | LineType::Quote => true,
        _ => false,
    }
}

fn get_partial_line_content(line_type: &LineType, line: &str) -> String {
    let encoded_line = line.replace("<", "&lt;").replace(">", "&gt;");
    return match line_type {
        LineType::ListItem => format!("<li>{}</li>", encoded_line[2..].trim()),
        LineType::Quote => encoded_line[1..].trim().to_string(),
        LineType::PreformattedText => format!("{}\n", encoded_line),
        LineType::PreformattedToggle => encoded_line[3..].trim().to_string(),
        _ => "".to_string(),
    }
}

fn get_full_line_content(line_type: &LineType, line: &str) -> String {
    let encoded_line = line.replace("<", "&lt;").replace(">", "&gt;");
     match line_type {
        LineType::Text => format!("<p>{}</p>\n", encoded_line.trim()),
        LineType::Blank => "<br>\n".to_string(),
        LineType::Link => {
            let url = get_link_address(line);
            if url.starts_with("gemini:") {
                format!("<div><a href=\"{}\">{}</a></div>\n", url, get_link_content(line))
            } else {
                format!("<div><a href=\"{}\">{}</a></div>\n", url.replace(".gmi", ".html"), get_link_content(line))
            }
        },
        LineType::Heading1 => format!("<h1>{}</h1>\n", encoded_line[1..].trim()),
        LineType::Heading2 => format!("<h2>{}</h2>\n", encoded_line[2..].trim()),
        LineType::Heading3 => format!("<h3>{}</h3>\n", encoded_line[3..].trim()),
        _ => "".to_string(),
    }
}

fn get_heading_wrapper(heading_stack: &mut Vec<u8>, line_type: &LineType) -> String {
    let mut string = String::new();
    let current_heading: u8 = match line_type {
        LineType::Heading1 => 1,
        LineType::Heading2 => 2,
        LineType::Heading3 => 3,
        _ => 255
    };

    if current_heading < 255 {
        while let Some(open_heading) = heading_stack.pop() {
            // You just encountered a more important heading.
            // Put it back. Desist.
            if open_heading < current_heading {
                heading_stack.push(open_heading);
                break;
            }

            string.push_str("</div>");

            if open_heading == current_heading {
                break;
            }
        }
        heading_stack.push(current_heading);
        string.push_str(&format!("<div class=\"h{}\">", current_heading));
    }

    return string;
}

fn close_heading_wrapper(heading_stack: &mut Vec<u8>) -> String {
    let mut string = String::new();
    while let Some(_open_heading) = heading_stack.pop() {
        string.push_str("</div>");
    }
    return string;
}

fn get_line_opener(line_type: &LineType, block_label: Option<&String>) -> String {
    match line_type {
        LineType::ListItem => "<ul>".to_string(),
        LineType::Quote => "<blockquote>".to_string(),
        LineType::PreformattedText => {
            if let Some(label) = &block_label {
                return format!("<pre role=\"img\" aria-label=\"{}\">", label);
            } else {
                return "<pre>".to_string();
            }
        },
        _ => "".to_string(),
    }
}

fn get_line_closer(line_type: &LineType) -> &'static str {
    match line_type {
        LineType::ListItem => "</ul>\n",
        LineType::Quote => "</blockquote>\n",
        LineType::PreformattedText => "</pre>\n",
        _ => "",
    }
}

fn get_link_content(line: &str) -> &str {
    let components: Vec<&str> = line[2..].trim().splitn(2, " ").collect();
    if components.len() > 1 {
        return components[1].trim()
    }
    components[0].trim()
}

fn get_link_address(line: &str) -> &str {
    let components: Vec<&str> = line[2..].trim().splitn(2, " ").collect();
    components[0].trim()
}

fn identify_line(line: &str, is_preformatted: bool) -> LineType {
    if line.starts_with("```") {
        return LineType::PreformattedToggle;
    }
    if is_preformatted {
        return LineType::PreformattedText;
    }
    if line.is_empty() {
        return LineType::Blank;
    }
    if line.starts_with("=>") {
        return LineType::Link;
    }
    if line.starts_with("* ") {
        return LineType::ListItem;
    }
    if line.starts_with(">") {
        return LineType::Quote;
    }
    if line.starts_with("###") {
        return LineType::Heading3;
    }
    if line.starts_with("##") {
        return LineType::Heading2;
    }
    if line.starts_with("#") {
        return LineType::Heading1;
    }

    LineType::Text
}

#[derive(PartialEq, Eq)]
enum LineType {
    Text,
    Blank,
    Link,
    PreformattedToggle,
    PreformattedText,
    Heading1,
    Heading2,
    Heading3,
    ListItem,
    Quote
}