// This is a fork of https://github.com/mehmetcansahin/html-purifier

use lol_html::html_content::{Comment, Element};
use lol_html::{comments, element, rewrite_str, RewriteStrSettings};

pub struct AllowedElement {
    pub name: &'static str,
    pub attributes: &'static [&'static str],
}

const ALLOWED: &'static [AllowedElement] = &[
    AllowedElement {
        name: "div",
        attributes: &[],
    },
    AllowedElement {
        name: "b",
        attributes: &[],
    },
    AllowedElement {
        name: "strong",
        attributes: &[],
    },
    AllowedElement {
        name: "i",
        attributes: &[],
    },
    AllowedElement {
        name: "em",
        attributes: &[],
    },
    AllowedElement {
        name: "u",
        attributes: &[],
    },
    AllowedElement {
        name: "a",
        attributes: &["href", "title"],
    },
    AllowedElement {
        name: "ul",
        attributes: &[],
    },
    AllowedElement {
        name: "ol",
        attributes: &[],
    },
    AllowedElement {
        name: "li",
        attributes: &[],
    },
    AllowedElement {
        name: "p",
        attributes: &["style"],
    },
    AllowedElement {
        name: "br",
        attributes: &[],
    },
    AllowedElement {
        name: "span",
        attributes: &["style"],
    },
    AllowedElement {
        name: "img",
        attributes: &["width", "height", "alt", "src"],
    },
];

pub fn process_message_html(input: &str) -> String {
    let element_handler = |el: &mut Element| {
        let find = ALLOWED.iter().find(|e| e.name.eq(&el.tag_name()));
        match find {
            Some(find) => {
                let remove_attributes = el
                    .attributes()
                    .iter()
                    .filter(|e| find.attributes.iter().any(|a| a.eq(&e.name())) == false)
                    .map(|m| m.name())
                    .collect::<Vec<String>>();
                for attr in remove_attributes {
                    el.remove_attribute(&attr);
                }
            }
            None => {
                el.remove_and_keep_content();
            }
        }
        if el.tag_name() == "a" {
            el.set_attribute("target", "_blank");
        }
        Ok(())
    };
    let comment_handler = |c: &mut Comment| {
        c.remove();
        Ok(())
    };
    let output = rewrite_str(
        input,
        RewriteStrSettings {
            element_content_handlers: vec![
                element!("*", element_handler),
                comments!("*", comment_handler),
            ],
            ..RewriteStrSettings::default()
        },
    )
    .unwrap();
    return output;
}