use async_trait::async_trait;
use fluffer::GemBytes;
use std::fmt::Display;

use crate::error::GementionError;
pub(crate) enum MentionType {
    Reply,
    Like,
}

pub(crate) struct Mention {
    mention_type: MentionType,
    user: String,
    content: Option<String>,
}

// This is for converting an incoming Titan request into a mention. It
// is very flexible: If the incoming value matches a specific format,
// it'll accurately convert the stringi nto a proper mention.
// Otherwise, it just assumes comment. An error is returned only if
// input is not utf8.
impl TryFrom<Vec<u8>> for Mention {
    type Error = GementionError;

    fn try_from(content: Vec<u8>) -> Result<Self, Self::Error> {
        let content = std::str::from_utf8(&content)?;
        Ok(Mention {
            mention_type: MentionType::Reply,
            user: "".to_string(),
            content: None,
        })
    }
}

impl Display for MentionType {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Reply => write!(f, "Reply"),
            Self::Like => write!(f, "Like"),
        }
    }
}

#[async_trait]
impl GemBytes for Mention {
    async fn gem_bytes(self) -> Vec<u8> {
        // TODO change output based on mention type:
        // Reply/comment = current format.
        // Like = "<user> liked this"

        let headline = format!("## {} from {}", self.mention_type, self.user);
        let content = self.content.unwrap_or(String::from("[no content]"));

        format!("20 text/gemini\r\n{}\n\n{}", headline, content).into_bytes()
    }
}