foukoapi 0.1.2-alpha.1

//! Context passed to every command handler.

use crate::{keyboard::Reply, platform::PlatformKind, Result};
use std::sync::Arc;

/// A lightweight handle to an incoming update.
///
/// A `Ctx` is what every handler receives. It exposes the platform the
/// message came from, the raw text, and a [`reply`](Ctx::reply) helper
/// that sends a message back through the same platform. It also carries
/// an optional [`edit_reply`](Ctx::edit_reply) that rewrites the bot's
/// own message in place instead of sending a new one: the button-bearing
/// message on callback updates, the last reply sent through this context
/// on regular messages.
#[derive(Clone)]
pub struct Ctx {
    pub(crate) inner: Arc<CtxInner>,
}

pub(crate) struct CtxInner {
    pub(crate) platform: PlatformKind,
    pub(crate) chat_id: String,
    pub(crate) user_id: String,
    pub(crate) text: String,
    pub(crate) reply_fn: ReplyFn,
    /// Display name of the sender, when the adapter provides one (Telegram
    /// first name / username, Discord global or user name). `None` if
    /// unknown.
    pub(crate) user_name: Option<String>,
    /// `true` when this message is a reply to one of the bot's own
    /// messages. Lets handlers treat "replying to the bot" as addressing
    /// it directly.
    pub(crate) is_reply_to_bot: bool,
    /// `Some(true)` / `Some(false)` when the adapter knows for sure,
    /// `None` when it doesn't. Handlers that need a definitive answer
    /// should fall back to chat_id/user_id heuristics themselves.
    pub(crate) is_dm: Option<bool>,
    /// When this update came from a button press, the callback id the
    /// adapter associated with the pressed button. `None` for regular
    /// text messages.
    pub(crate) callback_data: Option<String>,
    /// Lets a handler rewrite one of the **bot's own messages** in
    /// place instead of sending a new one. On callback updates it
    /// targets the message that carried the pressed button; on regular
    /// messages adapters wire it to the last reply sent through this
    /// context. `None` when the platform can't edit.
    pub(crate) edit_fn: Option<EditFn>,
    /// Optional lookup for the sending user's avatar URL.
    pub(crate) avatar_fn: Option<UrlFn>,
    /// Optional lookup for the sending user's banner URL (may hit the
    /// network on platforms that don't include it in the event).
    pub(crate) banner_fn: Option<UrlFn>,
    /// Optional lookup for chat/server info.
    pub(crate) chatinfo_fn: Option<ChatInfoFn>,
    /// Optional "user, I'm working on it" typing indicator.
    pub(crate) typing_fn: Option<TypingFn>,
    /// Optional self-deleting message sender for transient notices.
    pub(crate) temp_reply_fn: Option<TempReplyFn>,
    /// Optional lookup of another user's avatar by id.
    pub(crate) user_avatar_fn: Option<UserUrlFn>,
    /// Lazy download of the first image attached to the incoming
    /// message. Adapters set it only when the update carries one.
    pub(crate) image_fn: Option<ImageFn>,
    /// `true` when the incoming message carries an image. Known up
    /// front from the update, no download involved.
    pub(crate) has_image: bool,
}

/// Adapter-provided send callback. Takes a fully built [`Reply`] and sends
/// it back through the underlying platform.
pub type ReplyFn =
    Box<dyn Fn(Reply) -> futures::future::BoxFuture<'static, Result<()>> + Send + Sync + 'static>;

/// Adapter-provided edit callback. Rewrites one of the bot's own
/// messages in place: the button-bearing message on callback updates,
/// the last reply sent through this context on regular messages.
pub type EditFn =
    Arc<dyn Fn(Reply) -> futures::future::BoxFuture<'static, Result<()>> + Send + Sync + 'static>;

/// Adapter-provided lookup returning an optional URL (avatar, banner, ...).
/// Resolves to `None` when the platform can't supply one.
pub type UrlFn =
    Arc<dyn Fn() -> futures::future::BoxFuture<'static, Result<Option<String>>> + Send + Sync>;

/// Adapter-provided lookup for chat/server info.
pub type ChatInfoFn =
    Arc<dyn Fn() -> futures::future::BoxFuture<'static, Result<ChatInfo>> + Send + Sync>;
/// Adapter-provided "show a typing indicator" callback.
pub type TypingFn = Arc<dyn Fn() -> futures::future::BoxFuture<'static, Result<()>> + Send + Sync>;

/// Adapter-provided "send a message that deletes itself" callback. Takes
/// the reply and how long it should live, in seconds.
pub type TempReplyFn =
    Arc<dyn Fn(Reply, u64) -> futures::future::BoxFuture<'static, Result<()>> + Send + Sync>;

/// Adapter-provided lookup for another user's avatar URL by their id.
/// May hit the network. Resolves to `None` when the user can't be found
/// or the platform doesn't expose avatars.
pub type UserUrlFn = Arc<
    dyn Fn(String) -> futures::future::BoxFuture<'static, Result<Option<String>>> + Send + Sync,
>;

/// Adapter-provided download of the incoming message's image bytes.
/// Resolves to `None` when the image turns out to be unavailable.
pub type ImageFn =
    Arc<dyn Fn() -> futures::future::BoxFuture<'static, Result<Option<Vec<u8>>>> + Send + Sync>;

/// Cross-platform snapshot of the chat/server a command ran in.
///
/// Filled by [`Ctx::chat_info`]. Fields an adapter can't determine are
/// left `None`, so a handler renders whatever is present.
#[derive(Debug, Clone, Default)]
pub struct ChatInfo {
    /// Platform id of the chat/guild.
    pub id: String,
    /// Display name / title, if any.
    pub title: Option<String>,
    /// Approximate member count, if the platform reports one.
    pub member_count: Option<u64>,
    /// Icon / avatar URL for the chat, if any.
    pub icon_url: Option<String>,
    /// Description / topic, if any.
    pub description: Option<String>,
    /// Whether this is a one-to-one/private chat rather than a group/guild.
    pub is_private: bool,
}

impl Ctx {
    /// Build a `Ctx` from its parts. Adapters use this when they receive an
    /// update from their underlying client.
    pub fn new(
        platform: PlatformKind,
        chat_id: impl Into<String>,
        user_id: impl Into<String>,
        text: impl Into<String>,
        reply_fn: ReplyFn,
    ) -> Self {
        Self {
            inner: Arc::new(CtxInner {
                platform,
                chat_id: chat_id.into(),
                user_id: user_id.into(),
                text: text.into(),
                reply_fn,
                user_name: None,
                is_reply_to_bot: false,
                is_dm: None,
                callback_data: None,
                edit_fn: None,
                avatar_fn: None,
                banner_fn: None,
                chatinfo_fn: None,
                typing_fn: None,
                temp_reply_fn: None,
                user_avatar_fn: None,
                image_fn: None,
                has_image: false,
            }),
        }
    }

    /// Builder-style variant of [`Ctx::new`] that also records whether the
    /// update came from a direct message. Adapters that can tell for sure
    /// should use this; others keep passing `None` via [`Ctx::new`].
    pub fn new_full(
        platform: PlatformKind,
        chat_id: impl Into<String>,
        user_id: impl Into<String>,
        text: impl Into<String>,
        reply_fn: ReplyFn,
        is_dm: Option<bool>,
        callback_data: Option<String>,
    ) -> Self {
        Self {
            inner: Arc::new(CtxInner {
                platform,
                chat_id: chat_id.into(),
                user_id: user_id.into(),
                text: text.into(),
                reply_fn,
                user_name: None,
                is_reply_to_bot: false,
                is_dm,
                callback_data,
                edit_fn: None,
                avatar_fn: None,
                banner_fn: None,
                chatinfo_fn: None,
                typing_fn: None,
                temp_reply_fn: None,
                user_avatar_fn: None,
                image_fn: None,
                has_image: false,
            }),
        }
    }

    /// Same as [`Ctx::new_full`], plus an `edit_fn` that rewrites one of
    /// the bot's own messages. Adapters use this on callback updates (edit
    /// the button-bearing message) and on regular messages (edit the last
    /// reply sent through this context).
    #[allow(clippy::too_many_arguments)]
    pub fn new_with_edit(
        platform: PlatformKind,
        chat_id: impl Into<String>,
        user_id: impl Into<String>,
        text: impl Into<String>,
        reply_fn: ReplyFn,
        is_dm: Option<bool>,
        callback_data: Option<String>,
        edit_fn: Option<EditFn>,
    ) -> Self {
        Self {
            inner: Arc::new(CtxInner {
                platform,
                chat_id: chat_id.into(),
                user_id: user_id.into(),
                text: text.into(),
                reply_fn,
                user_name: None,
                is_reply_to_bot: false,
                is_dm,
                callback_data,
                edit_fn,
                avatar_fn: None,
                banner_fn: None,
                chatinfo_fn: None,
                typing_fn: None,
                temp_reply_fn: None,
                user_avatar_fn: None,
                image_fn: None,
                has_image: false,
            }),
        }
    }

    /// Attach adapter capability lookups (avatar/banner/chat-info) to a
    /// freshly built `Ctx`. Adapters call this right after construction,
    /// before the context is cloned into handlers, so the in-place update
    /// through `Arc::get_mut` always succeeds. Pass `None` for anything the
    /// platform can't provide.
    pub fn with_lookups(
        mut self,
        avatar_fn: Option<UrlFn>,
        banner_fn: Option<UrlFn>,
        chatinfo_fn: Option<ChatInfoFn>,
    ) -> Self {
        if let Some(inner) = Arc::get_mut(&mut self.inner) {
            inner.avatar_fn = avatar_fn;
            inner.banner_fn = banner_fn;
            inner.chatinfo_fn = chatinfo_fn;
        }
        self
    }

    /// Attach a typing-indicator callback. Adapters set this right after
    /// construction, same as [`Ctx::with_lookups`].
    pub fn with_typing(mut self, typing_fn: Option<TypingFn>) -> Self {
        if let Some(inner) = Arc::get_mut(&mut self.inner) {
            inner.typing_fn = typing_fn;
        }
        self
    }

    /// Attach a self-deleting message sender for transient notices.
    pub fn with_temp_reply(mut self, temp_reply_fn: Option<TempReplyFn>) -> Self {
        if let Some(inner) = Arc::get_mut(&mut self.inner) {
            inner.temp_reply_fn = temp_reply_fn;
        }
        self
    }

    /// Attach a by-id avatar lookup for other users.
    pub fn with_user_avatar(mut self, user_avatar_fn: Option<UserUrlFn>) -> Self {
        if let Some(inner) = Arc::get_mut(&mut self.inner) {
            inner.user_avatar_fn = user_avatar_fn;
        }
        self
    }

    /// Attach the incoming-image capability: `has` says whether the
    /// update carries an image (known up front), `image_fn` downloads
    /// its bytes on demand. Adapters set both together.
    pub(crate) fn with_incoming_image(mut self, has: bool, image_fn: Option<ImageFn>) -> Self {
        if let Some(inner) = Arc::get_mut(&mut self.inner) {
            inner.has_image = has;
            inner.image_fn = image_fn;
        }
        self
    }

    /// Record the sender's display name. Adapters set this at construction.
    pub fn with_user_name(mut self, name: Option<String>) -> Self {
        if let Some(inner) = Arc::get_mut(&mut self.inner) {
            inner.user_name = name;
        }
        self
    }

    /// Mark this update as a reply to one of the bot's own messages.
    pub fn with_reply_to_bot(mut self, yes: bool) -> Self {
        if let Some(inner) = Arc::get_mut(&mut self.inner) {
            inner.is_reply_to_bot = yes;
        }
        self
    }

    /// `true` when the user replied to a message the bot sent.
    pub fn is_reply_to_bot(&self) -> bool {
        self.inner.is_reply_to_bot
    }

    /// The sender's display name, if the platform provided one.
    pub fn user_name(&self) -> Option<&str> {
        self.inner.user_name.as_deref()
    }

    /// Which platform sent this update.
    pub fn platform(&self) -> PlatformKind {
        self.inner.platform
    }

    /// The chat/channel id this update came from, as a string so it's
    /// platform-agnostic.
    pub fn chat_id(&self) -> &str {
        &self.inner.chat_id
    }

    /// Id of the user who sent this update.
    pub fn user_id(&self) -> &str {
        &self.inner.user_id
    }

    /// Raw text of the incoming message.
    pub fn text(&self) -> &str {
        &self.inner.text
    }

    /// Everything after the command, trimmed.
    ///
    /// For `"/roll 3d6"` this returns `"3d6"`.
    /// For `"/help"` it returns `""`.
    pub fn args(&self) -> &str {
        self.inner
            .text
            .split_once(char::is_whitespace)
            .map(|(_, rest)| rest.trim())
            .unwrap_or("")
    }

    /// `true` when we are certain this update is a direct/private chat with
    /// the bot (one-on-one conversation). `false` when it's definitely a
    /// group/channel. Adapters that can't tell return `false` conservatively,
    /// so treat the answer as "is this safe to post private info into?".
    pub fn is_dm(&self) -> bool {
        match self.inner.is_dm {
            Some(v) => v,
            None => {
                // Fallback heuristic. Telegram uses the same id for private
                // chat and user, so they happen to match. Discord/Matrix
                // channels have distinct ids, so we bail.
                matches!(self.inner.platform, PlatformKind::Telegram)
                    && self.inner.chat_id == self.inner.user_id
            }
        }
    }

    /// Callback data attached to this update, when the user pressed a
    /// button registered via [`crate::Keyboard`]. `None` for regular text.
    pub fn callback_data(&self) -> Option<&str> {
        self.inner.callback_data.as_deref()
    }

    /// `true` when this update came from a button press (as opposed to
    /// a typed message). Convenience wrapper around
    /// [`Ctx::callback_data`].
    pub fn is_callback(&self) -> bool {
        self.inner.callback_data.is_some()
    }

    /// Send a plain-text reply back to the same chat on the same platform.
    pub async fn reply(&self, text: impl Into<String>) -> Result<()> {
        (self.inner.reply_fn)(Reply::text(text)).await
    }

    /// Send a reply with attached buttons / keyboard.
    pub async fn reply_with(&self, reply: impl Into<Reply>) -> Result<()> {
        (self.inner.reply_fn)(reply.into()).await
    }

    /// Rewrite the bot's own message in place with `reply`'s text /
    /// keyboard instead of sending a new one. On a callback update
    /// that's the message that carried the pressed button; on a regular
    /// message it's the last reply the bot sent through this `Ctx` -
    /// which is what makes streaming (send a placeholder, then keep
    /// editing it) work in plain chats. Falls back to a fresh message
    /// when there's nothing to edit yet (no reply sent, platform
    /// doesn't support editing, original message gone, etc.) so callers
    /// don't need to branch. Text longer than one message is truncated:
    /// edits can't split into several messages the way sends do.
    pub async fn edit_reply(&self, reply: impl Into<Reply>) -> Result<()> {
        let r = reply.into();
        if let Some(edit) = &self.inner.edit_fn {
            return (edit)(r).await;
        }
        (self.inner.reply_fn)(r).await
    }

    /// URL of the sending user's avatar, when the platform can supply one.
    /// Returns `Ok(None)` if it can't (e.g. no adapter support).
    pub async fn avatar_url(&self) -> Result<Option<String>> {
        match &self.inner.avatar_fn {
            Some(f) => f().await,
            None => Ok(None),
        }
    }

    /// URL of *another* user's avatar, looked up by their platform id.
    /// May make a network request. `Ok(None)` when the user can't be
    /// resolved or the platform has no adapter support for this.
    pub async fn avatar_url_of(&self, user_id: &str) -> Result<Option<String>> {
        match &self.inner.user_avatar_fn {
            Some(f) => f(user_id.to_owned()).await,
            None => Ok(None),
        }
    }

    /// URL of the sending user's profile banner, when available. May make a
    /// network request on platforms that don't include it in the event.
    pub async fn banner_url(&self) -> Result<Option<String>> {
        match &self.inner.banner_fn {
            Some(f) => f().await,
            None => Ok(None),
        }
    }

    /// Info about the chat/server this update came from. Returns
    /// [`ChatInfo`] with whatever fields the platform can determine; errors
    /// only if the lookup itself fails. Without adapter support you get a
    /// minimal `ChatInfo` carrying just the chat id.
    pub async fn chat_info(&self) -> Result<ChatInfo> {
        match &self.inner.chatinfo_fn {
            Some(f) => f().await,
            None => Ok(ChatInfo {
                id: self.inner.chat_id.clone(),
                is_private: self.is_dm(),
                ..Default::default()
            }),
        }
    }

    /// Show a "typing..." indicator in the chat, if the platform supports it.
    /// Handy right before a slow operation so the user knows the bot is
    /// working. A no-op where it isn't supported; errors are swallowed so a
    /// failed indicator never breaks the actual reply.
    pub async fn typing(&self) {
        if let Some(f) = &self.inner.typing_fn {
            let _ = f().await;
        }
    }

    /// Send a notice that removes itself after `secs` seconds - for
    /// transient warnings ("slow down", "not your button") that would
    /// otherwise pile up in the chat. Falls back to a normal reply where
    /// the platform can't delete messages.
    pub async fn reply_temporary(&self, reply: impl Into<Reply>, secs: u64) -> Result<()> {
        let r = reply.into();
        if let Some(f) = &self.inner.temp_reply_fn {
            return f(r, secs).await;
        }
        (self.inner.reply_fn)(r).await
    }

    /// Bytes of the first image attached to the incoming message (photo,
    /// image document/attachment), if any. Lazy: downloads on first call.
    pub async fn incoming_image(&self) -> Result<Option<Vec<u8>>> {
        match &self.inner.image_fn {
            Some(f) => f().await,
            None => Ok(None),
        }
    }

    /// True when the incoming message carries an image (no download).
    pub fn has_incoming_image(&self) -> bool {
        self.inner.has_image
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn noop_reply() -> ReplyFn {
        Box::new(|_| Box::pin(async { Ok(()) }))
    }

    #[tokio::test]
    async fn no_incoming_image_by_default() {
        let ctx = Ctx::new(PlatformKind::Telegram, "1", "2", "hi", noop_reply());
        assert!(!ctx.has_incoming_image());
        assert!(ctx.incoming_image().await.unwrap().is_none());
    }

    #[tokio::test]
    async fn incoming_image_capability_resolves() {
        let lookup: ImageFn = Arc::new(|| Box::pin(async { Ok(Some(vec![1, 2, 3])) }));
        let ctx = Ctx::new(PlatformKind::Discord, "1", "2", "", noop_reply())
            .with_incoming_image(true, Some(lookup));
        assert!(ctx.has_incoming_image());
        assert_eq!(ctx.incoming_image().await.unwrap(), Some(vec![1, 2, 3]));
    }
}