pub fn parse(source: &str) -> String {

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

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

    for line in lines {
        let mut line_type = LineType::Text;
        if line.len() > 2 {
            let end = line.char_indices().map(|(i, _)| i).nth(2).unwrap();
            line_type = identify_line(&(line[..end]), is_preformatted);
        }
        match line_type {
            LineType::PreformattedToggle => is_preformatted = !is_preformatted,
            _ => {
                // 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));
                        }
                    } else {
                        html.push_str(get_line_opener(&line_type));
                    }

                    let line_content = get_partial_line_content(&line_type, line);
                    html.push_str(&line_content);
                } else {
                    let line_content = get_full_line_content(&line_type, line);
                    html.push_str(&line_content);
                }
                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
}

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

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

fn get_full_line_content(line_type: &LineType, line: &str) -> String {
     match line_type {
        LineType::Text => format!("<p>{}</p>\n", line.trim()),
        LineType::Blank => "<br/>\n".to_string(),
        LineType::Link => format!("<div><a href=\"{}\">{}</a></div>\n", get_link_address(line), get_link_content(line)),
        LineType::Heading1 => format!("<h1>{}</h1>\n", line[1..].trim()),
        LineType::Heading2 => format!("<h2>{}</h2>\n", line[2..].trim()),
        LineType::Heading3 => format!("<h3>{}</h3>\n", line[3..].trim()),
        _ => "".to_string(),
    }
}

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

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
}