//! Websocket subscribable channel data structure.
use std::borrow::Cow;
use std::fmt;

use RoomName;

/// Different channels one can subscribe to.
pub enum Channel<'a> {
    /// Server messages (TODO: find message here).
    ServerMessages,
    /// User CPU and memory usage updates. Sent at the end of each tick.
    UserCpu {
        /// The user ID of the subscription.
        user_id: Cow<'a, str>,
    },
    /// User message updates. Sent when the user receives any new message.
    UserMessages {
        /// The user ID of the subscription.
        user_id: Cow<'a, str>,
    },
    /// Specific conversation alerts. Updates when a new message is received from a particular user.
    UserConversation {
        /// The user ID of the connected user.
        user_id: Cow<'a, str>,
        /// The user ID on the other side of the conversation to listen to.
        target_user_id: Cow<'a, str>,
    },
    /// User credit alerts. Updates whenever the user's credit changes.
    UserCredits {
        /// The user ID of the subscription.
        user_id: Cow<'a, str>,
    },
    /// Memory path alerts. Updates whenever this specific memory path changes.
    UserMemoryPath {
        /// The user ID of the subscription.
        user_id: Cow<'a, str>,
        /// The memory path, separated with '.'.
        path: Cow<'a, str>,
    },
    /// Console alerts. Updates at the end of every tick with all console messages during that tick.
    UserConsole {
        /// The user ID of the subscription.
        user_id: Cow<'a, str>,
    },
    /// User active branch changes: updates whenever the active branch changes.
    UserActiveBranch {
        /// The user ID of the subscription.
        user_id: Cow<'a, str>,
    },
    /// Room overview updates. Updates at the end of every tick with all room positions for each nondescript
    /// type of structure (road, wall, energy, or player owned).
    RoomMapView {
        /// The shard the room is in, if any.
        shard_name: Option<Cow<'a, str>>,
        /// The room name of the subscription.
        room_name: RoomName,
    },
    /// Detailed room updates. Updates at the end of every tick with all room object properties which have
    /// changed since the last tick.
    ///
    /// Note: this is limited to 2 per user account at a time, and if there are more than 2 room subscriptions active,
    /// it is random which 2 will received updates on any given ticks. Rooms which are not updated do receive an error
    /// message on "off" ticks.
    RoomDetail {
        /// The shard the room is in, if any.
        shard_name: Option<Cow<'a, str>>,
        /// The room name of the subscription.
        room_name: RoomName,
    },
    /// A channel specified by the exact channel id.
    Other {
        /// The channel protocol string.
        channel: Cow<'a, str>,
    },
}

impl Channel<'static> {
    /// Creates a channel subscribing to server messages.
    pub fn server_messages() -> Self {
        Channel::ServerMessages
    }

    /// Creates a channel subscribing to map-view updates of a room, with no shard.
    ///
    /// Warning: creating a channel with a shard name when the server does not have any shards or creating a channel
    /// without a shard name on a sharded server will both result in the subscribe silently failing.
    pub fn room_map_view_ps(room_name: RoomName) -> Self {
        Channel::RoomMapView {
            shard_name: None,
            room_name: room_name,
        }
    }

    /// Creates a channel subscribing to detailed updates of a room's contents, with no shard.
    ///
    /// Note: this is limited to 2 per user account at a time, and if there are more than 2 room subscriptions active,
    /// it is random which 2 will received updates on any given ticks. Rooms which are not updated do receive an error
    /// message on "off" ticks.
    ///
    /// Warning: creating a channel with a shard name when the server does not have any shards or creating a channel
    /// without a shard name on a sharded server will both result in the subscribe silently failing.
    pub fn room_detail_ps(room_name: RoomName) -> Self {
        Channel::RoomDetail {
            shard_name: None,
            room_name: room_name,
        }
    }
}

impl<'a> Channel<'a> {
    /// Creates a channel subscribing to map-view updates of a room.
    ///
    /// Warning: creating a channel with a shard name when the server does not have any shards or creating a channel
    /// without a shard name on a sharded server will both result in the subscribe silently failing.
    pub fn room_map_view<T: Into<Cow<'a, str>>>(room_name: RoomName, shard_name: Option<T>) -> Self {
        Channel::RoomMapView {
            shard_name: shard_name.map(Into::into),
            room_name: room_name,
        }
    }

    /// Creates a channel subscribing to detailed updates of a room's contents.
    ///
    /// Warning: creating a channel with a shard name when the server does not have any shards or creating a channel
    /// without a shard name on a sharded server will both result in the subscribe silently failing.
    ///
    /// Note: this is limited to 2 per user account at a time, and if there are more than 2 room subscriptions active,
    /// it is random which 2 will received updates on any given ticks. Rooms which are not updated do receive an error
    /// message on "off" ticks.
    pub fn room_detail<T: Into<Cow<'a, str>>>(room_name: RoomName, shard_name: Option<T>) -> Self {
        Channel::RoomDetail {
            shard_name: shard_name.map(Into::into),
            room_name: room_name,
        }
    }

    /// Creates a channel subscribing to a user's CPU and memory.
    pub fn user_cpu<T: Into<Cow<'a, str>>>(user_id: T) -> Self {
        Channel::UserCpu {
            user_id: user_id.into(),
        }
    }

    /// Creates a channel subscribing to a user's new message notifications.
    pub fn user_messages<T: Into<Cow<'a, str>>>(user_id: T) -> Self {
        Channel::UserMessages {
            user_id: user_id.into(),
        }
    }

    /// Creates a channel subscribing to new messages in a user's specific conversation.
    pub fn user_conversation<T, U>(user_id: T, target_user_id: U) -> Self
    where
        T: Into<Cow<'a, str>>,
        U: Into<Cow<'a, str>>,
    {
        Channel::UserConversation {
            user_id: user_id.into(),
            target_user_id: target_user_id.into(),
        }
    }

    /// Creates a channel subscribing to a user's credit count.
    pub fn user_credits<T: Into<Cow<'a, str>>>(user_id: T) -> Self {
        Channel::UserCredits {
            user_id: user_id.into(),
        }
    }

    /// Creates a channel subscribing to a path in a user's memory.
    pub fn user_memory_path<T, U>(user_id: T, path: U) -> Self
    where
        T: Into<Cow<'a, str>>,
        U: Into<Cow<'a, str>>,
    {
        Channel::UserMemoryPath {
            user_id: user_id.into(),
            path: path.into(),
        }
    }

    /// Creates a channel subscribing to a user's console output.
    pub fn user_console<T: Into<Cow<'a, str>>>(user_id: T) -> Self {
        Channel::UserConsole {
            user_id: user_id.into(),
        }
    }

    /// Creates a channel subscribing to when a user's active code branch changes.
    pub fn user_active_branch<T: Into<Cow<'a, str>>>(user_id: T) -> Self {
        Channel::UserActiveBranch {
            user_id: user_id.into(),
        }
    }

    /// Creates a channel using the fully specified channel name.
    pub fn other<T: Into<Cow<'a, str>>>(channel: T) -> Self {
        Channel::Other {
            channel: channel.into(),
        }
    }
}

impl<'a> fmt::Display for Channel<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Channel::ServerMessages => write!(f, "server-message"),
            Channel::UserCpu { ref user_id } => write!(f, "user:{}/cpu", user_id),
            Channel::UserMessages { ref user_id } => write!(f, "user:{}/newMessage", user_id),
            Channel::UserConversation {
                ref user_id,
                ref target_user_id,
            } => write!(f, "user:{}/message:{}", user_id, target_user_id),
            Channel::UserCredits { ref user_id } => write!(f, "user:{}/money", user_id),
            Channel::UserMemoryPath {
                ref user_id,
                ref path,
            } => write!(f, "user:{}/memory/{}", user_id, path),
            Channel::UserConsole { ref user_id } => write!(f, "user:{}/console", user_id),
            Channel::UserActiveBranch { ref user_id } => write!(f, "user:{}/set-active-branch", user_id),
            Channel::RoomMapView {
                ref room_name,
                ref shard_name,
            } => match *shard_name {
                Some(ref shard_name) => write!(f, "roomMap2:{}/{}", shard_name, room_name),
                None => write!(f, "roomMap2:{}", room_name),
            },
            Channel::RoomDetail {
                ref room_name,
                ref shard_name,
            } => match *shard_name {
                Some(ref shard_name) => write!(f, "room:{}/{}", shard_name, room_name),
                None => write!(f, "room:{}", room_name),
            },
            Channel::Other { ref channel } => write!(f, "{}", channel),
        }
    }
}