Dealer: Rework context retrieval

connect/src/context_resolver.rs

@@ -0,0 +1,347 @@
+use crate::{
+    core::{Error, Session},
+    protocol::{
+        autoplay_context_request::AutoplayContextRequest, context::Context,
+        transfer_state::TransferState,
+    },
+    state::{
+        context::{ContextType, UpdateContext},
+        ConnectState,
+    },
+};
+use std::cmp::PartialEq;
+use std::{
+    collections::{HashMap, VecDeque},
+    fmt::{Display, Formatter},
+    hash::Hash,
+    time::Duration,
+};
+use thiserror::Error as ThisError;
+use tokio::time::Instant;
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
+enum Resolve {
+    Uri(String),
+    Context(Context),
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
+pub(super) enum ContextAction {
+    Append,
+    Replace,
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
+pub(super) struct ResolveContext {
+    resolve: Resolve,
+    fallback: Option<String>,
+    update: UpdateContext,
+    action: ContextAction,
+}
+
+impl ResolveContext {
+    fn append_context(uri: impl Into<String>) -> Self {
+        Self {
+            resolve: Resolve::Uri(uri.into()),
+            fallback: None,
+            update: UpdateContext::Default,
+            action: ContextAction::Append,
+        }
+    }
+
+    pub fn from_uri(
+        uri: impl Into<String>,
+        fallback: impl Into<String>,
+        update: UpdateContext,
+        action: ContextAction,
+    ) -> Self {
+        let fallback_uri = fallback.into();
+        Self {
+            resolve: Resolve::Uri(uri.into()),
+            fallback: (!fallback_uri.is_empty()).then_some(fallback_uri),
+            update,
+            action,
+        }
+    }
+
+    pub fn from_context(context: Context, update: UpdateContext, action: ContextAction) -> Self {
+        Self {
+            resolve: Resolve::Context(context),
+            fallback: None,
+            update,
+            action,
+        }
+    }
+
+    /// the uri which should be used to resolve the context, might not be the context uri
+    fn resolve_uri(&self) -> Option<&str> {
+        // it's important to call this always, or at least for every ResolveContext
+        // otherwise we might not even check if we need to fallback and just use the fallback uri
+        match self.resolve {
+            Resolve::Uri(ref uri) => ConnectState::valid_resolve_uri(uri),
+            Resolve::Context(ref ctx) => ConnectState::get_context_uri_from_context(ctx),
+        }
+        .or(self.fallback.as_deref())
+    }
+
+    /// the actual context uri
+    fn context_uri(&self) -> &str {
+        match self.resolve {
+            Resolve::Uri(ref uri) => uri,
+            Resolve::Context(ref ctx) => ctx.uri.as_deref().unwrap_or_default(),
+        }
+    }
+}
+
+impl Display for ResolveContext {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "resolve_uri: <{:?}>, context_uri: <{}>, update: <{:?}>",
+            self.resolve_uri(),
+            self.context_uri(),
+            self.update,
+        )
+    }
+}
+
+#[derive(Debug, ThisError)]
+enum ContextResolverError {
+    #[error("no next context to resolve")]
+    NoNext,
+    #[error("tried appending context with {0} pages")]
+    UnexpectedPagesSize(usize),
+    #[error("tried resolving not allowed context: {0:?}")]
+    NotAllowedContext(String),
+}
+
+impl From<ContextResolverError> for Error {
+    fn from(value: ContextResolverError) -> Self {
+        Error::failed_precondition(value)
+    }
+}
+
+pub struct ContextResolver {
+    session: Session,
+    queue: VecDeque<ResolveContext>,
+    unavailable_contexts: HashMap<ResolveContext, Instant>,
+}
+
+// time after which an unavailable context is retried
+const RETRY_UNAVAILABLE: Duration = Duration::from_secs(3600);
+
+impl ContextResolver {
+    pub fn new(session: Session) -> Self {
+        Self {
+            session,
+            queue: VecDeque::new(),
+            unavailable_contexts: HashMap::new(),
+        }
+    }
+
+    pub fn add(&mut self, resolve: ResolveContext) {
+        let last_try = self
+            .unavailable_contexts
+            .get(&resolve)
+            .map(|i| i.duration_since(Instant::now()));
+
+        let last_try = if matches!(last_try, Some(last_try) if last_try > RETRY_UNAVAILABLE) {
+            let _ = self.unavailable_contexts.remove(&resolve);
+            debug!(
+                "context was requested {}s ago, trying again to resolve the requested context",
+                last_try.expect("checked by condition").as_secs()
+            );
+            None
+        } else {
+            last_try
+        };
+
+        if last_try.is_some() {
+            debug!("tried loading unavailable context: {resolve}");
+            return;
+        } else if self.queue.contains(&resolve) {
+            debug!("update for {resolve} is already added");
+            return;
+        } else {
+            trace!(
+                "added {} to resolver queue",
+                resolve.resolve_uri().unwrap_or(resolve.context_uri())
+            )
+        }
+
+        self.queue.push_back(resolve)
+    }
+
+    pub fn add_list(&mut self, resolve: Vec<ResolveContext>) {
+        for resolve in resolve {
+            self.add(resolve)
+        }
+    }
+
+    pub fn remove_used_and_invalid(&mut self) {
+        if let Some((_, _, remove)) = self.find_next() {
+            let _ = self.queue.drain(0..remove); // remove invalid
+        }
+        self.queue.pop_front(); // remove used
+    }
+
+    pub fn clear(&mut self) {
+        self.queue = VecDeque::new()
+    }
+
+    fn find_next(&self) -> Option<(&ResolveContext, &str, usize)> {
+        for idx in 0..self.queue.len() {
+            let next = self.queue.get(idx)?;
+            match next.resolve_uri() {
+                None => {
+                    warn!("skipped {idx} because of invalid resolve_uri: {next}");
+                    continue;
+                }
+                Some(uri) => return Some((next, uri, idx)),
+            }
+        }
+        None
+    }
+
+    pub fn has_next(&self) -> bool {
+        self.find_next().is_some()
+    }
+
+    pub async fn get_next_context(
+        &self,
+        recent_track_uri: impl Fn() -> Vec<String>,
+    ) -> Result<Context, Error> {
+        let (next, resolve_uri, _) = self.find_next().ok_or(ContextResolverError::NoNext)?;
+
+        match next.update {
+            UpdateContext::Default => {
+                let mut ctx = self.session.spclient().get_context(resolve_uri).await;
+                if let Ok(ctx) = ctx.as_mut() {
+                    ctx.uri = Some(next.context_uri().to_string());
+                    ctx.url = ctx.uri.as_ref().map(|s| format!("context://{s}"));
+                }
+
+                ctx
+            }
+            UpdateContext::Autoplay => {
+                if resolve_uri.contains("spotify:show:") || resolve_uri.contains("spotify:episode:")
+                {
+                    // autoplay is not supported for podcasts
+                    Err(ContextResolverError::NotAllowedContext(
+                        resolve_uri.to_string(),
+                    ))?
+                }
+
+                let request = AutoplayContextRequest {
+                    context_uri: Some(resolve_uri.to_string()),
+                    recent_track_uri: recent_track_uri(),
+                    ..Default::default()
+                };
+                self.session.spclient().get_autoplay_context(&request).await
+            }
+        }
+    }
+
+    pub fn mark_next_unavailable(&mut self) {
+        if let Some((next, _, _)) = self.find_next() {
+            self.unavailable_contexts
+                .insert(next.clone(), Instant::now());
+        }
+    }
+
+    pub fn apply_next_context(
+        &self,
+        state: &mut ConnectState,
+        mut context: Context,
+    ) -> Result<Option<Vec<ResolveContext>>, Error> {
+        let (next, _, _) = self.find_next().ok_or(ContextResolverError::NoNext)?;
+
+        let remaining = match next.action {
+            ContextAction::Append if context.pages.len() == 1 => state
+                .fill_context_from_page(context.pages.remove(0))
+                .map(|_| None),
+            ContextAction::Replace => {
+                let remaining = state.update_context(context, next.update);
+                if let Resolve::Context(ref ctx) = next.resolve {
+                    state.merge_context(Some(ctx.clone()));
+                }
+
+                remaining
+            }
+            ContextAction::Append => {
+                warn!("unexpected page size: {context:#?}");
+                Err(ContextResolverError::UnexpectedPagesSize(context.pages.len()).into())
+            }
+        }?;
+
+        Ok(remaining.map(|remaining| {
+            remaining
+                .into_iter()
+                .map(ResolveContext::append_context)
+                .collect::<Vec<_>>()
+        }))
+    }
+
+    pub fn try_finish(
+        &self,
+        state: &mut ConnectState,
+        transfer_state: &mut Option<TransferState>,
+    ) -> bool {
+        let (next, _, _) = match self.find_next() {
+            None => return false,
+            Some(next) => next,
+        };
+
+        // when there is only one update type, we are the last of our kind, so we should update the state
+        if self
+            .queue
+            .iter()
+            .filter(|resolve| resolve.update == next.update)
+            .count()
+            != 1
+        {
+            return false;
+        }
+
+        match (next.update, state.active_context) {
+            (UpdateContext::Default, ContextType::Default) | (UpdateContext::Autoplay, _) => {
+                debug!(
+                    "last item of type <{:?}>, finishing state setup",
+                    next.update
+                );
+            }
+            (UpdateContext::Default, _) => {
+                debug!("skipped finishing default, because it isn't the active context");
+                return false;
+            }
+        }
+
+        let active_ctx = state.get_context(state.active_context);
+        let res = if let Some(transfer_state) = transfer_state.take() {
+            state.finish_transfer(transfer_state)
+        } else if state.shuffling_context() {
+            state.shuffle()
+        } else if matches!(active_ctx, Ok(ctx) if ctx.index.track == 0) {
+            // has context, and context is not touched
+            // when the index is not zero, the next index was already evaluated elsewhere
+            let ctx = active_ctx.expect("checked by precondition");
+            let idx = ConnectState::find_index_in_context(ctx, |t| {
+                state.current_track(|c| t.uri == c.uri)
+            })
+            .ok();
+
+            state.reset_playback_to_position(idx)
+        } else {
+            state.fill_up_next_tracks()
+        };
+
+        if let Err(why) = res {
+            error!("setup of state failed: {why}, last used resolve {next:#?}")
+        }
+
+        state.update_restrictions();
+        state.update_queue_revision();
+
+        true
+    }
+}

connect/src/lib.rs

@@ -5,6 +5,7 @@ use librespot_core as core;
 use librespot_playback as playback;
 use librespot_protocol as protocol;
 
+mod context_resolver;
 mod model;
 pub mod spirc;
 pub mod state;