use regex::Regex;

#[derive(Debug)]
pub enum Error{
  IllegalLink(String),
  ReqwestError(reqwest::Error),
  JsonError(json::Error),
  ArticleNotFound,
}

impl From<reqwest::Error> for Error {
  fn from(value: reqwest::Error) -> Self {
    Self::ReqwestError(value)
  }
}

impl From<json::Error> for Error {
  fn from(value: json::Error) -> Self {
    Self::JsonError(value)
  }
}

pub fn slug_from_link(link: String) -> Result<String, Error> {
  let regex_pattern = Regex::new(r"\.wikipedia\.org\/wiki\/|\?").unwrap();
  let link_parts: Vec<&str> = regex_pattern.split(&link).collect();
  if link_parts.len() >= 2 {
    Ok(link_parts[1].to_string())
  } else {
    Err(Error::IllegalLink(link))
  }
}

pub async fn title_from_slug(slug: String) -> Result<String, Error> {
  let escaped_slug = slug.replace("/", "%2F");
  let request_url =
    format!(
      "https://api.wikimedia.org/core/v1/wikipedia/en/page/{escaped_slug}/bare"
    );
  let response = reqwest::get(request_url).await?;
  let json_body = response.text().await?;
  let body = json::parse(&json_body)?;
  match body["title"].as_str() {
    Some(x) => Ok(x.to_string()),
    None => Err(Error::ArticleNotFound)
  }
}

pub async fn post_body(link: String) -> Result<String, Error> {
  let title = title_from_slug(slug_from_link(link.clone())?).await?;
  Ok(format!("Today's wikipedia article is {title}\n\n\
  {link}\n\n\
  #wikipedia").to_string())
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn test_slug_from_link_1() {
    assert_eq!(slug_from_link("https://en.wikipedia.org/wiki/Buck-a-beer?wprov=sfla1".to_string()).unwrap().as_str(), "Buck-a-beer")
  }

  #[test]
  fn test_slug_from_link_2() {
    assert_eq!(slug_from_link("https://en.wikipedia.org/wiki/GNU/Linux_naming_controversy".to_string()).unwrap().as_str(), "GNU/Linux_naming_controversy")
  }

  #[tokio::test]
  async fn test_title_from_slug_1() {
    assert_eq!(title_from_slug("Buck-a-beer".to_string()).await.unwrap().as_str(), "Buck-a-beer")
  }

  #[tokio::test]
  async fn test_title_from_slug_2() {
    assert_eq!(title_from_slug("GNU/Linux_naming_controversy".to_string()).await.unwrap().as_str(), "GNU/Linux naming controversy")
  }

  #[tokio::test]
  async fn test_post_body_1() {
    let body = post_body("https://en.wikipedia.org/wiki/GNU%2FLinux_naming_controversy".to_string()).await.unwrap();
    let expected = "Today's wikipedia article is GNU/Linux naming controversy\n\n\
      https://en.wikipedia.org/wiki/GNU%2FLinux_naming_controversy\n\n\
      #wikipedia";
    assert_eq!(body, expected)
  }
}