use comrak::nodes::NodeValue;
use comrak::{Arena, Options, format_html, parse_document};

fn replace_text(document: &str, orig_string: &str, replacement: &str) -> String {
    // The returned nodes are created in the supplied Arena, and are bound by its lifetime.
    let arena = Arena::new();

    // Parse the document into a root `Node`
    let root = parse_document(&arena, document, &Options::default());

    // Iterate over all the descendants of root.
    for node in root.descendants() {
        if let NodeValue::Text(ref mut text) = node.data_mut().value {
            // If the node is a text node, replace `orig_string` with `replacement`.
            *text = text.to_mut().replace(orig_string, replacement).into()
        }
    }

    let mut html = String::new();
    format_html(root, &Options::default(), &mut html).unwrap();

    html
}

fn main() {
    let doc =
        "Hello, pretty world!\n\n1. Do you like [pretty](#) paintings?\n2. Or *pretty* music?\n";
    let orig = "pretty";
    let repl = "beautiful";
    let html = replace_text(doc, orig, repl);

    println!("{}", html);
}

#[cfg(test)]
mod tests {
    use super::*;
    use ntest::{assert_false, assert_true};

    #[test]
    fn sample_replace() {
        let doc = "Replace deeply nested *[foo](https://example.com)* with bar.\n\nReplace shallow foo with bar.";
        let orig = "foo";
        let repl = "bar";
        let html = replace_text(&doc, &orig, &repl);
        println!("{:?}", html);
        assert_false!(html.contains("foo"));
        assert_true!(html.contains("bar"));
        assert_true!(html.contains("<a"));
        assert_true!(html.contains("<p"));
    }
}
