//! User information-related models.

use serde_json;
use std::fmt;
use super::utils::deserialize_u16;
use super::prelude::*;
use internal::prelude::*;
use model::misc::Mentionable;

use chrono::NaiveDateTime;
use std::fmt::Write;

/// Information about the current user.
#[derive(Clone, Default, Debug, Deserialize, Serialize)]
pub struct CurrentUser {
    pub id: UserId,
    pub avatar: Option<String>,
    #[serde(default)] pub bot: bool,
    #[serde(deserialize_with = "deserialize_u16")] pub discriminator: u16,
    pub email: Option<String>,
    pub mfa_enabled: bool,
    #[serde(rename = "username")] pub name: String,
    pub verified: bool,
}

impl CurrentUser {
    /// Returns the formatted URL of the user's icon, if one exists.
    ///
    /// This will produce a WEBP image URL, or GIF if the user has a GIF avatar.
    ///
    /// # Examples
    ///
    /// Print out the current user's avatar url if one is set:
    ///
    /// ```rust,no_run
    /// # use serenity::CACHE;
    /// #
    /// # let cache = CACHE.read();
    /// #
    /// // assuming the cache has been unlocked
    /// let user = &cache.user;
    ///
    /// match user.avatar_url() {
    ///     Some(url) => println!("{}'s avatar can be found at {}", user.name, url),
    ///     None => println!("{} does not have an avatar set.", user.name)
    /// }
    /// ```
    #[inline]
    pub fn avatar_url(&self) -> Option<String> { avatar_url(self.id, self.avatar.as_ref()) }

    /// Returns the formatted URL to the user's default avatar URL.
    ///
    /// This will produce a PNG URL.
    #[inline]
    pub fn default_avatar_url(&self) -> String { default_avatar_url(self.discriminator) }

    /// Retrieves the URL to the current user's avatar, falling back to the
    /// default avatar if needed.
    ///
    /// This will call [`avatar_url`] first, and if that returns `None`, it
    /// then falls back to [`default_avatar_url`].
    ///
    /// [`avatar_url`]: #method.avatar_url
    /// [`default_avatar_url`]: #method.default_avatar_url
    pub fn face(&self) -> String {
        self.avatar_url()
            .unwrap_or_else(|| self.default_avatar_url())
    }

    /// Returns a static formatted URL of the user's icon, if one exists.
    ///
    /// This will always produce a WEBP image URL.
    ///
    /// # Examples
    ///
    /// Print out the current user's static avatar url if one is set:
    ///
    /// ```rust,no_run
    /// # use serenity::CACHE;
    /// #
    /// # let cache = CACHE.read();
    /// #
    /// // assuming the cache has been unlocked
    /// let user = &cache.user;
    ///
    /// match user.static_avatar_url() {
    ///     Some(url) => println!("{}'s static avatar can be found at {}", user.name, url),
    ///     None => println!("Could not get static avatar for {}.", user.name)
    /// }
    /// ```
    #[inline]
    pub fn static_avatar_url(&self) -> Option<String> {
        static_avatar_url(self.id, self.avatar.as_ref())
    }

    /// Returns the tag of the current user.
    ///
    /// # Examples
    ///
    /// Print out the current user's distinct identifier (e.g., Username#1234):
    ///
    /// ```rust,no_run
    /// # use serenity::CACHE;
    /// #
    /// # let cache = CACHE.read();
    /// #
    /// // assuming the cache has been unlocked
    /// println!("The current user's distinct identifier is {}", cache.user.tag());
    /// ```
    #[inline]
    pub fn tag(&self) -> String { tag(&self.name, self.discriminator) }
}

/// An enum that represents a default avatar.
///
/// The default avatar is calculated via the result of `discriminator % 5`.
///
/// The has of the avatar can be retrieved via calling [`name`] on the enum.
///
/// [`name`]: #method.name
#[derive(Copy, Clone, Debug, Deserialize, Hash, Eq, PartialEq, PartialOrd, Ord, Serialize)]
pub enum DefaultAvatar {
    /// The avatar when the result is `0`.
    #[serde(rename = "6debd47ed13483642cf09e832ed0bc1b")]
    Blurple,
    /// The avatar when the result is `1`.
    #[serde(rename = "322c936a8c8be1b803cd94861bdfa868")]
    Grey,
    /// The avatar when the result is `2`.
    #[serde(rename = "dd4dbc0016779df1378e7812eabaa04d")]
    Green,
    /// The avatar when the result is `3`.
    #[serde(rename = "0e291f67c9274a1abdddeb3fd919cbaa")]
    Orange,
    /// The avatar when the result is `4`.
    #[serde(rename = "1cbd08c76f8af6dddce02c5138971129")]
    Red,
}

impl DefaultAvatar {
    /// Retrieves the String hash of the default avatar.
    pub fn name(&self) -> Result<String> { serde_json::to_string(self).map_err(From::from) }
}

/// The representation of a user's status.
///
/// # Examples
///
/// - [`DoNotDisturb`];
/// - [`Invisible`].
///
/// [`DoNotDisturb`]: #variant.DoNotDisturb
/// [`Invisible`]: #variant.Invisible
#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, PartialEq, PartialOrd, Ord, Serialize)]
pub enum OnlineStatus {
    #[serde(rename = "dnd")] DoNotDisturb,
    #[serde(rename = "idle")] Idle,
    #[serde(rename = "invisible")] Invisible,
    #[serde(rename = "offline")] Offline,
    #[serde(rename = "online")] Online,
}

impl OnlineStatus {
    pub fn name(&self) -> &str {
        match *self {
            OnlineStatus::DoNotDisturb => "dnd",
            OnlineStatus::Idle => "idle",
            OnlineStatus::Invisible => "invisible",
            OnlineStatus::Offline => "offline",
            OnlineStatus::Online => "online",
        }
    }
}

impl Default for OnlineStatus {
    fn default() -> OnlineStatus { OnlineStatus::Online }
}

/// Information about a user.
#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct User {
    /// The unique Id of the user. Can be used to calculate the account's
    /// creation date.
    pub id: UserId,
    /// Optional avatar hash.
    pub avatar: Option<String>,
    /// Indicator of whether the user is a bot.
    #[serde(default)]
    pub bot: bool,
    /// The account's discriminator to differentiate the user from others with
    /// the same [`name`]. The name+discriminator pair is always unique.
    ///
    /// [`name`]: #structfield.name
    #[serde(deserialize_with = "deserialize_u16")]
    pub discriminator: u16,
    /// The account's username. Changing username will trigger a discriminator
    /// change if the username+discriminator pair becomes non-unique.
    #[serde(rename = "username")]
    pub name: String,
}

use std::hash::{Hash, Hasher};

impl PartialEq for User {
    fn eq(&self, other: &Self) -> bool {
        self.id == other.id
    }
}

impl Eq for User {}

impl Hash for User {
    fn hash<H: Hasher>(&self, hasher: &mut H) {
        self.id.hash(hasher);
    }
}

impl User {
    /// Returns the formatted URL of the user's icon, if one exists.
    ///
    /// This will produce a WEBP image URL, or GIF if the user has a GIF avatar.
    #[inline]
    pub fn avatar_url(&self) -> Option<String> { avatar_url(self.id, self.avatar.as_ref()) }

    /// Retrieves the time that this user was created at.
    #[inline]
    pub fn created_at(&self) -> NaiveDateTime { self.id.created_at() }

    /// Returns the formatted URL to the user's default avatar URL.
    ///
    /// This will produce a PNG URL.
    #[inline]
    pub fn default_avatar_url(&self) -> String { default_avatar_url(self.discriminator) }

    /// Retrieves the URL to the user's avatar, falling back to the default
    /// avatar if needed.
    ///
    /// This will call [`avatar_url`] first, and if that returns `None`, it
    /// then falls back to [`default_avatar_url`].
    ///
    /// [`avatar_url`]: #method.avatar_url
    /// [`default_avatar_url`]: #method.default_avatar_url
    pub fn face(&self) -> String {
        self.avatar_url()
            .unwrap_or_else(|| self.default_avatar_url())
    }

    /// Returns a static formatted URL of the user's icon, if one exists.
    ///
    /// This will always produce a WEBP image URL.
    #[inline]
    pub fn static_avatar_url(&self) -> Option<String> {
        static_avatar_url(self.id, self.avatar.as_ref())
    }

    /// Returns the "tag" for the user.
    ///
    /// The "tag" is defined as "username#discriminator", such as "zeyla#5479".
    ///
    /// # Examples
    ///
    /// Make a command to tell the user what their tag is:
    ///
    /// ```rust,no_run
    /// # use serenity::prelude::*;
    /// # use serenity::model::prelude::*;
    /// #
    /// use serenity::utils::MessageBuilder;
    /// use serenity::utils::ContentModifier::Bold;
    ///
    /// struct Handler;
    ///
    /// impl EventHandler for Handler {
    ///     fn message(&self, _: Context, msg: Message) {
    ///         if msg.content == "!mytag" {
    ///             let content = MessageBuilder::new()
    ///                 .push("Your tag is ")
    ///                 .push(Bold + msg.author.tag())
    ///                 .build();
    ///
    ///             let _ = msg.channel_id.say(&content);
    ///         }
    ///     }
    /// }
    /// let mut client = Client::new("token", Handler).unwrap();
    ///
    /// client.start().unwrap();
    /// ```
    #[inline]
    pub fn tag(&self) -> String { tag(&self.name, self.discriminator) }
}

impl fmt::Display for User {
    /// Formats a string which will mention the user.
    // This is in the format of: `<@USER_ID>`
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(&self.id.mention(), f)
    }
}

impl From<CurrentUser> for UserId {
    /// Gets the Id of a `CurrentUser` struct.
    fn from(current_user: CurrentUser) -> UserId { current_user.id }
}

impl<'a> From<&'a CurrentUser> for UserId {
    /// Gets the Id of a `CurrentUser` struct.
    fn from(current_user: &CurrentUser) -> UserId { current_user.id }
}

impl From<User> for UserId {
    /// Gets the Id of a `User`.
    fn from(user: User) -> UserId { user.id }
}

impl<'a> From<&'a User> for UserId {
    /// Gets the Id of a `User`.
    fn from(user: &User) -> UserId { user.id }
}

fn avatar_url(user_id: UserId, hash: Option<&String>) -> Option<String> {
    hash.map(|hash| {
        let ext = if hash.starts_with("a_") {
            "gif"
        } else {
            "webp"
        };

        cdn!("/avatars/{}/{}.{}?size=1024", user_id.0, hash, ext)
    })
}

fn default_avatar_url(discriminator: u16) -> String {
    cdn!("/embed/avatars/{}.png", discriminator % 5u16)
}

fn static_avatar_url(user_id: UserId, hash: Option<&String>) -> Option<String> {
    hash.map(|hash| cdn!("/avatars/{}/{}.webp?size=1024", user_id, hash))
}

fn tag(name: &str, discriminator: u16) -> String {
    // 32: max length of username
    // 1: `#`
    // 4: max length of discriminator
    let mut tag = String::with_capacity(37);
    tag.push_str(name);
    tag.push('#');
    let _ = write!(tag, "{:04}", discriminator);

    tag
}