//! Models for server and channel invites.

use std::ops::Deref;

use chrono::{DateTime, Utc};

use super::prelude::*;
#[cfg(all(feature = "cache", feature = "model"))]
use super::{utils as model_utils, Permissions};
#[cfg(feature = "model")]
use crate::builder::CreateInvite;
#[cfg(all(feature = "cache", feature = "model"))]
use crate::cache::Cache;
#[cfg(feature = "model")]
use crate::http::{CacheHttp, Http};
#[cfg(feature = "model")]
use crate::internal::prelude::*;
#[cfg(feature = "model")]
use crate::utils;

/// Information about an invite code.
///
/// Information can not be accessed for guilds the current user is banned from.
#[derive(Clone, Debug, Deserialize, Serialize)]
#[non_exhaustive]
pub struct Invite {
    /// The approximate number of [`Member`]s in the related [`Guild`].
    pub approximate_member_count: Option<u64>,
    /// The approximate number of [`Member`]s with an active session in the
    /// related [`Guild`].
    ///
    /// An active session is defined as an open, heartbeating WebSocket connection.
    /// These include [invisible][`OnlineStatus::Invisible`] members.
    pub approximate_presence_count: Option<u64>,
    /// The unique code for the invite.
    pub code: String,
    /// A representation of the minimal amount of information needed about the
    /// [`GuildChannel`] being invited to.
    pub channel: InviteChannel,
    /// A representation of the minimal amount of information needed about the
    /// [`Guild`] being invited to.
    pub guild: Option<InviteGuild>,
    /// A representation of the minimal amount of information needed about the
    /// [`User`] that created the invite.
    ///
    /// This can be [`None`] for invites created by Discord such as invite-widgets
    /// or vanity invite links.
    pub inviter: Option<InviteUser>,
}

#[cfg(feature = "model")]
impl Invite {
    /// Creates an invite for a [`GuildChannel`], providing a builder so that
    /// fields may optionally be set.
    ///
    /// See the documentation for the [`CreateInvite`] builder for information
    /// on how to use this and the default values that it provides.
    ///
    /// Requires the [Create Invite] permission.
    ///
    /// # Errors
    ///
    /// If the `cache` is enabled, returns a [`ModelError::InvalidPermissions`]
    /// if the current user does not have the required [permission].
    ///
    /// [`CreateInvite`]: crate::builder::CreateInvite
    /// [Create Invite]: Permissions::CREATE_INVITE
    /// [permission]: super::permissions
    #[inline]
    pub async fn create<F>(
        cache_http: impl CacheHttp,
        channel_id: impl Into<ChannelId>,
        f: F,
    ) -> Result<RichInvite>
    where
        F: FnOnce(CreateInvite) -> CreateInvite,
    {
        let channel_id = channel_id.into();

        #[cfg(feature = "cache")]
        {
            if let Some(cache) = cache_http.cache() {
                model_utils::user_has_perms_cache(
                    cache,
                    channel_id,
                    None,
                    Permissions::CREATE_INVITE,
                )
                .await?;
            }
        }

        let map = utils::hashmap_to_json_map(f(CreateInvite::default()).0);

        cache_http.http().create_invite(channel_id.0, &map).await
    }

    /// Deletes the invite.
    ///
    /// **Note**: Requires the [Manage Guild] permission.
    ///
    /// # Errors
    ///
    /// If the `cache` is enabled, returns a [`ModelError::InvalidPermissions`]
    /// if the current user does not have the required [permission].
    ///
    /// Otherwise may return [`Error::Http`] if permissions are lacking,
    /// or if the invite is invalid.
    ///
    /// [Manage Guild]: Permissions::MANAGE_GUILD
    /// [permission]: super::permissions
    /// [`Error::Http`]: crate::error::Error::Http
    pub async fn delete(&self, cache_http: impl CacheHttp) -> Result<Invite> {
        #[cfg(feature = "cache")]
        {
            if let Some(cache) = cache_http.cache() {
                let guild_id = self.guild.as_ref().map(|g| g.id);
                model_utils::user_has_perms_cache(
                    cache,
                    self.channel.id,
                    guild_id,
                    Permissions::MANAGE_GUILD,
                )
                .await?;
            }
        }

        cache_http.http().as_ref().delete_invite(&self.code).await
    }

    /// Gets the information about an invite.
    ///
    /// # Errors
    ///
    /// May return an [`Error::Http`] if the invite is invalid.
    /// Can also return an [`Error::Json`] if there is an error
    /// deserializing the API response.
    pub async fn get(http: impl AsRef<Http>, code: &str, stats: bool) -> Result<Invite> {
        let mut invite = code;

        #[cfg(feature = "utils")]
        {
            invite = crate::utils::parse_invite(invite);
        }

        http.as_ref().get_invite(invite, stats).await
    }

    /// Returns a URL to use for the invite.
    ///
    /// # Examples
    ///
    /// Retrieve the URL for an invite with the code `WxZumR`:
    ///
    /// ```rust
    /// # extern crate serde_json;
    /// # extern crate serenity;
    /// #
    /// # use serde_json::json;
    /// # use serenity::model::prelude::*;
    /// #
    /// # fn main() {
    /// # let invite = serde_json::from_value::<Invite>(json!({
    /// #     "approximate_member_count": Some(1812),
    /// #     "approximate_presence_count": Some(717),
    /// #     "code": "WxZumR",
    /// #     "channel": {
    /// #         "id": ChannelId(1),
    /// #         "name": "foo",
    /// #         "type": ChannelType::Text,
    /// #     },
    /// #     "guild": {
    /// #         "id": GuildId(2),
    /// #         "icon": None::<String>,
    /// #         "name": "bar",
    /// #         "splash_hash": None::<String>,
    /// #         "text_channel_count": 7,
    /// #         "voice_channel_count": 3,
    /// #     },
    /// #     "inviter": {
    /// #         "id": UserId(3),
    /// #         "username": "foo",
    /// #         "discriminator": "1234",
    /// #         "avatar": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
    /// #     },
    /// # })).unwrap();
    /// #
    /// assert_eq!(invite.url(), "https://discord.gg/WxZumR");
    /// # }
    /// ```
    pub fn url(&self) -> String {
        format!("https://discord.gg/{}", self.code)
    }
}

/// A minimal amount of information about the inviter (person who created the invite).
#[derive(Clone, Debug, Deserialize, Serialize)]
#[non_exhaustive]
pub struct InviteUser {
    pub id: UserId,
    #[serde(rename = "username")]
    pub name: String,
    #[serde(deserialize_with = "deserialize_u16")]
    pub discriminator: u16,
    pub avatar: Option<String>,
}

/// InviteUser implements a Deref to UserId so it gains the convenience methods
/// for converting it into a [`User`] instance.
impl Deref for InviteUser {
    type Target = UserId;

    fn deref(&self) -> &Self::Target {
        &self.id
    }
}

/// A minimal amount of information about the channel an invite points to.
#[non_exhaustive]
#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct InviteChannel {
    pub id: ChannelId,
    pub name: String,
    #[serde(rename = "type")]
    pub kind: ChannelType,
}

/// A minimal amount of information about the guild an invite points to.
#[derive(Clone, Debug, Deserialize, Serialize)]
#[non_exhaustive]
pub struct InviteGuild {
    pub id: GuildId,
    pub icon: Option<String>,
    pub name: String,
    pub splash: Option<String>,
    pub text_channel_count: Option<u64>,
    pub voice_channel_count: Option<u64>,
}

#[cfg(feature = "model")]
impl InviteGuild {
    /// Returns the Id of the shard associated with the guild.
    ///
    /// When the cache is enabled this will automatically retrieve the total
    /// number of shards.
    ///
    /// **Note**: When the cache is enabled, this function unlocks the cache to
    /// retrieve the total number of shards in use. If you already have the
    /// total, consider using [`utils::shard_id`].
    #[cfg(all(feature = "cache", feature = "utils"))]
    #[inline]
    pub async fn shard_id(&self, cache: impl AsRef<Cache>) -> u64 {
        self.id.shard_id(&cache).await
    }

    /// Returns the Id of the shard associated with the guild.
    ///
    /// When the cache is enabled this will automatically retrieve the total
    /// number of shards.
    ///
    /// When the cache is not enabled, the total number of shards being used
    /// will need to be passed.
    ///
    /// # Examples
    ///
    /// Retrieve the Id of the shard for a guild with Id `81384788765712384`,
    /// using 17 shards:
    ///
    /// ```rust,ignore
    /// use serenity::utils;
    ///
    /// // assumes a `guild` has already been bound
    ///
    /// assert_eq!(guild.shard_id(17), 7);
    /// ```
    #[cfg(all(feature = "utils", not(feature = "cache")))]
    #[inline]
    pub async fn shard_id(&self, shard_count: u64) -> u64 {
        self.id.shard_id(shard_count).await
    }
}

/// Detailed information about an invite.
/// This information can only be retrieved by anyone with the [Manage Guild]
/// permission. Otherwise, a minimal amount of information can be retrieved via
/// the [`Invite`] struct.
///
/// [Manage Guild]: Permissions::MANAGE_GUILD
#[derive(Clone, Debug, Deserialize, Serialize)]
#[non_exhaustive]
pub struct RichInvite {
    /// A representation of the minimal amount of information needed about the
    /// channel being invited to.
    pub channel: InviteChannel,
    /// The unique code for the invite.
    pub code: String,
    /// When the invite was created.
    pub created_at: DateTime<Utc>,
    /// A representation of the minimal amount of information needed about the
    /// [`Guild`] being invited to.
    pub guild: Option<InviteGuild>,
    /// The user that created the invite.
    pub inviter: User,
    /// The maximum age of the invite in seconds, from when it was created.
    pub max_age: u64,
    /// The maximum number of times that an invite may be used before it expires.

    /// Note that this does not supersede the [`Self::max_age`] value, if the value of
    /// [`Self::temporary`] is `true`. If the value of `temporary` is `false`, then the
    /// invite _will_ self-expire after the given number of max uses.

    /// If the value is `0`, then the invite is permanent.
    pub max_uses: u64,
    /// Indicator of whether the invite self-expires after a certain amount of
    /// time or uses.
    pub temporary: bool,
    /// The amount of times that an invite has been used.
    pub uses: u64,
}

#[cfg(feature = "model")]
impl RichInvite {
    /// Deletes the invite.
    ///
    /// Refer to [`Http::delete_invite`] for more information.
    ///
    /// **Note**: Requires the [Manage Guild] permission.
    ///
    /// # Errors
    ///
    /// If the `cache` feature is enabled, then this returns a
    /// [`ModelError::InvalidPermissions`] if the current user does not have
    /// the required [permission].
    ///
    /// [Manage Guild]: Permissions::MANAGE_GUILD
    /// [permission]: super::permissions
    pub async fn delete(&self, cache_http: impl CacheHttp) -> Result<Invite> {
        #[cfg(feature = "cache")]
        {
            if let Some(cache) = cache_http.cache() {
                let guild_id = self.guild.as_ref().map(|g| g.id);

                model_utils::user_has_perms_cache(
                    cache,
                    self.channel.id,
                    guild_id,
                    Permissions::MANAGE_GUILD,
                )
                .await?;
            }
        }

        cache_http.http().as_ref().delete_invite(&self.code).await
    }

    /// Returns a URL to use for the invite.
    ///
    /// # Examples
    ///
    /// Retrieve the URL for an invite with the code `WxZumR`:
    ///
    /// ```rust
    /// # extern crate serde_json;
    /// # extern crate serenity;
    /// #
    /// # use serde_json::json;
    /// # use serenity::model::prelude::*;
    /// #
    /// # fn main() {
    /// # let invite = serde_json::from_value::<RichInvite>(json!({
    /// #     "code": "WxZumR",
    /// #     "channel": {
    /// #         "id": ChannelId(1),
    /// #         "name": "foo",
    /// #         "type": ChannelType::Text,
    /// #     },
    /// #     "created_at": "2017-01-29T15:35:17.136000+00:00",
    /// #     "guild": {
    /// #         "id": GuildId(2),
    /// #         "icon": None::<String>,
    /// #         "name": "baz",
    /// #         "splash_hash": None::<String>,
    /// #         "text_channel_count": None::<u64>,
    /// #         "voice_channel_count": None::<u64>,
    /// #     },
    /// #     "inviter": {
    /// #         "avatar": None::<String>,
    /// #         "bot": false,
    /// #         "discriminator": 3,
    /// #         "id": UserId(4),
    /// #         "username": "qux",
    /// #         "public_flags": None::<UserPublicFlags>,
    /// #     },
    /// #     "max_age": 5,
    /// #     "max_uses": 6,
    /// #     "temporary": true,
    /// #     "uses": 7,
    /// # })).unwrap();
    /// #
    /// assert_eq!(invite.url(), "https://discord.gg/WxZumR");
    /// # }
    /// ```
    pub fn url(&self) -> String {
        format!("https://discord.gg/{}", self.code)
    }
}