martin-core 0.5.0

use std::sync::Arc;
use std::time::Duration;

use actix_web::web::Bytes;
use moka::future::Cache;
use tracing::{info, trace};

#[cfg(feature = "metrics")]
use crate::metrics::CACHE_REQUESTS_TOTAL;

/// Sprite cache for storing generated sprite sheets.
#[derive(Clone)]
pub struct SpriteCache {
    cache: Cache<SpriteCacheKey, Bytes>,
}

impl std::fmt::Debug for SpriteCache {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("SpriteCache")
            .field("entry_count", &self.cache.entry_count())
            .field("weighted_size", &self.cache.weighted_size())
            .finish()
    }
}

impl SpriteCache {
    /// Creates a new sprite cache with the specified maximum size in bytes.
    #[must_use]
    pub fn new(
        max_size_bytes: u64,
        expiry: Option<Duration>,
        idle_timeout: Option<Duration>,
    ) -> Self {
        let mut builder = Cache::builder()
            .name("sprite_cache")
            .weigher(|key: &SpriteCacheKey, value: &Bytes| -> u32 {
                size_of_val(key).try_into().unwrap_or(u32::MAX)
                    + value.len().try_into().unwrap_or(u32::MAX)
            })
            .max_capacity(max_size_bytes);
        if let Some(ttl) = expiry {
            builder = builder.time_to_live(ttl);
        }
        if let Some(tti) = idle_timeout {
            builder = builder.time_to_idle(tti);
        }
        Self {
            cache: builder.build(),
        }
    }

    /// Gets a json sprite sheet from cache or computes it using the provided function.
    pub async fn get_or_insert<F, Fut, E>(
        &self,
        ids: String,
        as_sdf: bool,
        as_json: bool,
        compute: F,
    ) -> Result<Bytes, Arc<E>>
    where
        F: FnOnce() -> Fut,
        Fut: Future<Output = Result<Bytes, E>>,
        E: Send + Sync + 'static,
    {
        let key = SpriteCacheKey::new(ids, as_sdf, as_json);
        let entry = self
            .cache
            .entry(key.clone())
            .or_try_insert_with(async move { compute().await })
            .await?;

        if entry.is_fresh() {
            #[cfg(feature = "metrics")]
            CACHE_REQUESTS_TOTAL
                .with_label_values(&["sprite", "miss"])
                .inc();
            hotpath::gauge!("sprite_cache_misses").inc(1.0);
            trace!("Sprite cache MISS for {key:?}");
        } else {
            #[cfg(feature = "metrics")]
            CACHE_REQUESTS_TOTAL
                .with_label_values(&["sprite", "hit"])
                .inc();
            hotpath::gauge!("sprite_cache_hits").inc(1.0);
            trace!(
                "Sprite cache HIT for {key:?} (entries={}, size={})",
                self.cache.entry_count(),
                self.cache.weighted_size()
            );
        }

        Ok(entry.into_value())
    }

    /// Invalidates all cached sprites that use the specified source ID.
    pub fn invalidate_source(&self, source_id: &str) {
        let source_id_owned = source_id.to_string();
        self.cache
            .invalidate_entries_if(move |key, _| key.ids.contains(&source_id_owned))
            .expect("invalidate_entries_if predicate should not error");
        info!("Invalidated sprite cache for source: {source_id}");
    }

    /// Invalidates all cached sprites.
    pub fn invalidate_all(&self) {
        self.cache.invalidate_all();
        info!("Invalidated all sprite cache entries");
    }

    /// Returns the number of cached entries.
    #[must_use]
    pub fn entry_count(&self) -> u64 {
        self.cache.entry_count()
    }

    /// Returns the total size of cached data in bytes.
    #[must_use]
    pub fn weighted_size(&self) -> u64 {
        self.cache.weighted_size()
    }

    /// Runs pending maintenance tasks (e.g. processing invalidation predicates).
    pub async fn run_pending_tasks(&self) {
        self.cache.run_pending_tasks().await;
    }
}

/// Optional wrapper for `SpriteCache`.
pub type OptSpriteCache = Option<SpriteCache>;

/// Constant representing no sprite cache configuration.
pub const NO_SPRITE_CACHE: OptSpriteCache = None;

/// Cache key for sprite data.
#[derive(Debug, Hash, PartialEq, Eq, Clone)]
struct SpriteCacheKey {
    ids: String,
    as_sdf: bool,
    as_json: bool,
}

impl SpriteCacheKey {
    fn new(ids: String, as_sdf: bool, as_json: bool) -> Self {
        Self {
            ids,
            as_sdf,
            as_json,
        }
    }
}