use std::fmt::{Display, Formatter};
use std::str::FromStr;

use serde::{Deserialize, Serialize};

use super::instance::Instance;

/// A user, defined by its username and instance.
///
/// # Textual Format
/// A user's textual reference is defined as:
///
/// `{username: String}:{instance: Instance}`
///
/// # Examples
/// For the user with the username `barson` and the instance `giterated.dev`,
/// the following [`User`] initialization would be valid:
///
/// ```
/// let user = User {
///     username: String::from("barson"),
///     instance: Instance::from_str("giterated.dev").unwrap()
/// };
///
/// // This is correct
/// assert_eq!(User::from_str("barson:giterated.dev").unwrap(), user);
/// ```
#[derive(Clone, Debug, Hash, PartialEq, Eq, Serialize, Deserialize)]
pub struct User {
    pub username: String,
    pub instance: Instance,
}

impl Display for User {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}:{}", self.username, self.instance.url)
    }
}

impl From<String> for User {
    fn from(user_string: String) -> Self {
        User::from_str(&user_string).unwrap()
    }
}

impl FromStr for User {
    type Err = ();

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let mut colon_split = s.split(':');
        let username = colon_split.next().unwrap().to_string();
        let instance = Instance::from_str(colon_split.next().unwrap()).unwrap();

        Ok(Self { username, instance })
    }
}