nigig-org/crates/apps/map/src/scheduler.rs

use super::cache::TileCache;
use super::geometry::*;
use super::tile::*;
use super::viewport::ViewportState;
use makepad_widgets::*;
use std::collections::{HashMap, HashSet};
use std::path::PathBuf;
use std::time::Instant;

// Security: Rate limiting constants (Phase 4: Security Hardening)
const DEFAULT_REQUESTS_PER_SECOND: f64 = 10.0;
const MAX_BURST_SIZE: f64 = 10.0;

/// Token bucket rate limiter for HTTP requests.
/// Prevents API abuse and protects against IP bans.
pub struct RateLimiter {
    tokens: f64,
    max_tokens: f64,
    refill_rate: f64,  // tokens per second
    last_refill: Instant,
}

impl RateLimiter {
    pub fn new(requests_per_second: f64) -> Self {
        Self {
            tokens: requests_per_second.min(MAX_BURST_SIZE),
            max_tokens: requests_per_second.min(MAX_BURST_SIZE),
            refill_rate: requests_per_second,
            last_refill: Instant::now(),
        }
    }

    /// Try to acquire a token. Returns true if successful, false if rate limited.
    pub fn try_acquire(&mut self) -> bool {
        self.refill();
        if self.tokens >= 1.0 {
            self.tokens -= 1.0;
            true
        } else {
            false
        }
    }

    fn refill(&mut self) {
        let now = Instant::now();
        let elapsed = now.duration_since(self.last_refill).as_secs_f64();
        self.tokens = (self.tokens + elapsed * self.refill_rate).min(self.max_tokens);
        self.last_refill = now;
    }

    /// Get current token count (for testing/debugging)
    #[cfg(test)]
    pub fn tokens(&self) -> f64 {
        self.tokens
    }
}

/// Configuration for the tile scheduler. Decouples scheduling from live properties.
pub struct SchedulerConfig {
    pub use_network: bool,
    pub use_local_mbtiles: bool,
    pub max_pending_requests: usize,
    pub max_local_tile_batch: usize,
    pub max_tile_retries: u8,
    pub local_mbtiles_path: String,
    pub local_tile_cache_dir: String,
}

impl Default for SchedulerConfig {
    fn default() -> Self {
        Self {
            use_network: true,
            use_local_mbtiles: true,
            max_pending_requests: MAX_PENDING_REQUESTS,
            max_local_tile_batch: MAX_LOCAL_TILE_BATCH,
            max_tile_retries: MAX_TILE_RETRIES,
            local_mbtiles_path: LOCAL_MBTILES_PATH.to_string(),
            local_tile_cache_dir: TILE_CACHE_DIR.to_string(),
        }
    }
}

/// Actions that the scheduler requests the caller to execute.
/// This decouples the scheduler from Cx/HTTP/thread pool.
pub enum TileAction {
    /// Load a batch of tiles from local mbtiles source.
    LoadLocalBatch {
        mbtiles_path: PathBuf,
        cache_dir: String,
        requested: Vec<TileKey>,
        style_epoch: u64,
        generation: u64,
    },
    /// Load a single tile from disk cache.
    LoadFromDiskCache {
        tile_key: TileKey,
        cache_path: std::path::PathBuf,
        style_epoch: u64,
        generation: u64,
    },
    /// Load a tile from the network via HTTP.
    LoadFromNetwork {
        request_id: LiveId,
        http_request: HttpRequest,
        tile_key: TileKey,
        generation: u64,
    },
    /// Nothing to do right now.
    Nothing,
}

/// Owns the tile request queue, retry logic, prioritization, and cancellation.
///
/// Does NOT know about rendering. Produces `TileAction`s for the caller to execute.
pub struct TileScheduler {
    visible_tiles: Vec<TileKey>,
    local_requested: HashSet<TileKey>,
    local_missing: HashSet<TileKey>,
    request_to_tile: HashMap<LiveId, PendingTileRequest>,
    next_request_id: u64,
    local_source_missing_logged: bool,
    /// Generation counter: incremented on zoom/theme change.
    /// All requests carry this value; stale results are discarded on arrival.
    current_generation: u64,
    /// The zoom level at which the current generation was created.
    /// Used to detect zoom-level changes that should bump the generation.
    generation_zoom_level: u32,
    /// Rate limiter for HTTP requests (Phase 4: Security Hardening)
    rate_limiter: RateLimiter,
}

impl Default for TileScheduler {
    fn default() -> Self {
        Self {
            visible_tiles: Vec::new(),
            local_requested: HashSet::new(),
            local_missing: HashSet::new(),
            request_to_tile: HashMap::new(),
            next_request_id: 1,
            local_source_missing_logged: false,
            current_generation: 1,
            generation_zoom_level: 0,
            rate_limiter: RateLimiter::new(DEFAULT_REQUESTS_PER_SECOND),
        }
    }
}

impl TileScheduler {
    pub fn new() -> Self {
        Self::default()
    }

    /// The current generation counter. Worker results with a stale generation are discarded.
    pub fn current_generation(&self) -> u64 {
        self.current_generation
    }

    /// Force-increment the generation (e.g. on theme change or explicit user action).
    pub fn reset_generation(&mut self) {
        self.current_generation = self.current_generation.wrapping_add(1);
        if self.current_generation == 0 {
            self.current_generation = 1;
        }
    }

    pub fn visible_tiles(&self) -> &[TileKey] {
        &self.visible_tiles
    }

    pub fn is_local_missing(&self, key: TileKey) -> bool {
        self.local_missing.contains(&key)
    }

    pub fn is_local_requested(&self, key: TileKey) -> bool {
        self.local_requested.contains(&key)
    }

    /// Recompute visible tiles from viewport, update scheduler state.
    /// Returns true if the visible set changed.
    /// Automatically bumps generation if the zoom level changed.
    /// Only recomputes visible tiles when viewport is dirty (Phase 4 optimization).
    pub fn update_visible(&mut self, viewport: &mut ViewportState) -> bool {
        // Always compute on first call (visible_tiles is empty)
        // Only skip recomputation if viewport unchanged AND we have tiles
        if !self.visible_tiles.is_empty() && !viewport.dirty {
            return false;
        }
        
        // Use non-allocating method: reuse self.visible_tiles buffer
        viewport.visible_tile_keys_into(&mut self.visible_tiles);
        let changed = true; // We always recompute when called

        // Bump generation on zoom level change (prevents stale results)
        let new_zoom = self.visible_tiles.first().map(|k| k.z).unwrap_or(0);
        if new_zoom != self.generation_zoom_level && self.generation_zoom_level != 0 {
            self.current_generation = self.current_generation.wrapping_add(1);
            if self.current_generation == 0 {
                self.current_generation = 1;
            }
        }
        self.generation_zoom_level = new_zoom;

        viewport.clear_dirty();
        changed
    }

    /// Core scheduling: determine what tiles need loading and return actions.
    pub fn schedule(
        &mut self,
        cache: &TileCache,
        config: &SchedulerConfig,
        style_epoch: u64,
    ) -> Vec<TileAction> {
        let mut actions = Vec::new();
        let generation = self.current_generation;
        let _target_zoom = self
            .visible_tiles
            .first()
            .map(|k| k.z)
            .unwrap_or(0);

        // 1. Try local mbtiles batch loading
        if config.use_local_mbtiles {
            if let Some(action) = self.schedule_local_batch(cache, config, style_epoch, generation) {
                actions.push(action);
            }
        }

        // 2. Schedule individual tile requests
        let mut pending = cache.pending_loading();
        for key in self.visible_tiles.clone() {
            // Check retry
            if let Some(attempts) = cache.should_retry(key, config.max_tile_retries) {
                if pending < config.max_pending_requests {
                    if let Some(action) =
                        self.schedule_single_tile(key, attempts, config, style_epoch, generation)
                    {
                        actions.push(action);
                        pending += 1;
                    }
                }
                continue;
            }

            // Skip if already in cache or requested
            if cache.contains(key) {
                continue;
            }
            if self.local_missing.contains(&key) {
                if config.use_network && pending < config.max_pending_requests {
                    if let Some(action) =
                        self.schedule_single_tile(key, 0, config, style_epoch, generation)
                    {
                        actions.push(action);
                        pending += 1;
                    }
                }
                continue;
            }

            // New tile
            if let Some(action) =
                self.schedule_single_tile(key, 0, config, style_epoch, generation)
            {
                actions.push(action);
                pending += 1;
            }
        }

        actions
    }

    fn schedule_local_batch(
        &mut self,
        cache: &TileCache,
        config: &SchedulerConfig,
        style_epoch: u64,
        generation: u64,
    ) -> Option<TileAction> {
        let mut missing = Vec::new();
        for &key in &self.visible_tiles {
            if cache.contains(key)
                || self.local_requested.contains(&key)
                || self.local_missing.contains(&key)
            {
                continue;
            }
            missing.push(key);
        }
        if missing.is_empty() {
            return None;
        }
        if missing.len() > config.max_local_tile_batch {
            missing.truncate(config.max_local_tile_batch);
        }

        // Check mbtiles path exists
        let mbtiles_path = resolve_mbtiles_path(
            &config.local_mbtiles_path,
            &config.local_tile_cache_dir,
        );
        if !mbtiles_path.is_file() {
            if !self.local_source_missing_logged {
                log!(
                    "NigigMapView: local mbtiles source missing at {} (resolved from: {})",
                    mbtiles_path.display(),
                    config.local_mbtiles_path
                );
                self.local_source_missing_logged = true;
            }
            return None;
        }

        for key in &missing {
            self.local_requested.insert(*key);
        }

        Some(TileAction::LoadLocalBatch {
            mbtiles_path,
            cache_dir: config.local_tile_cache_dir.clone(),
            requested: missing,
            style_epoch,
            generation,
        })
    }

    fn schedule_single_tile(
        &mut self,
        tile_key: TileKey,
        attempts: u8,
        config: &SchedulerConfig,
        style_epoch: u64,
        generation: u64,
    ) -> Option<TileAction> {
        // Disk cache path (only for network tiles without local mbtiles)
        if attempts == 0 && !config.use_local_mbtiles {
            let cache_path = tile_data_cache_path_for(tile_key);
            if cache_path.is_file() {
                return Some(TileAction::LoadFromDiskCache {
                    tile_key,
                    cache_path,
                    style_epoch,
                    generation,
                });
            }
        }

        if !config.use_network {
            return None;
        }

        // Security: Rate limiting (Phase 4: Security Hardening)
        if !self.rate_limiter.try_acquire() {
            log!("NigigMapView: rate limit exceeded, deferring tile request for {:?}", tile_key);
            return None;
        }

        let request_id = LiveId(self.next_request_id);
        self.next_request_id = self.next_request_id.wrapping_add(1);
        if self.next_request_id == 0 {
            self.next_request_id = 1;
        }

        let query = overpass_query(tile_key);
        let endpoint = overpass_endpoint(attempts);
        let mut http_request = HttpRequest::new(endpoint.to_string(), HttpMethod::POST);
        http_request.set_header("Content-Type".to_string(), "text/plain".to_string());
        http_request.set_header("Accept".to_string(), "application/json".to_string());
        http_request.set_header("User-Agent".to_string(), "makepad-map-view".to_string());
        http_request.set_body_string(&query);

        self.request_to_tile
            .insert(request_id, PendingTileRequest { tile_key, endpoint, generation });

        Some(TileAction::LoadFromNetwork {
            request_id,
            http_request,
            tile_key,
            generation,
        })
    }

    // --- Worker message handling ---

    pub fn on_batch_loaded(&mut self, requested: Vec<TileKey>, loaded_keys: &HashSet<TileKey>) {
        for key in &requested {
            self.local_requested.remove(key);
            if !loaded_keys.contains(key) {
                self.local_missing.insert(*key);
            }
        }
    }

    pub fn on_batch_failed(&mut self, requested: Vec<TileKey>) {
        for key in &requested {
            self.local_requested.remove(&key);
        }
    }

    pub fn on_tile_loaded(&mut self, _tile_key: TileKey) {
        // Nothing to clean up for network tiles
    }

    pub fn on_tile_failed(&mut self, _tile_key: TileKey) {
    }

    // --- HTTP integration ---

    pub fn on_http_response(&mut self, request_id: LiveId) -> Option<(TileKey, u64)> {
        self.request_to_tile.remove(&request_id).map(|p| (p.tile_key, p.generation))
    }

    pub fn on_http_error(&mut self, request_id: LiveId) -> Option<(TileKey, u64)> {
        self.request_to_tile.remove(&request_id).map(|p| (p.tile_key, p.generation))
    }

    pub fn register_http_request(&mut self, request_id: LiveId, tile_key: TileKey) {
        // Already registered in schedule_single_tile
        let _ = (request_id, tile_key);
    }

    // --- Theme change ---

    pub fn reset(&mut self) {
        self.local_requested.clear();
        self.local_missing.clear();
        self.request_to_tile.clear();
    }

    /// Remove all entries from local_missing so tiles can be re-requested.
    pub fn clear_missing(&mut self) {
        self.local_missing.clear();
    }
}

/// Resolve the mbtiles path using multiple fallback locations.
pub fn resolve_mbtiles_path(local_mbtiles_path: &str, cache_dir: &str) -> PathBuf {
    let p = std::path::Path::new(local_mbtiles_path);
    if p.is_file() {
        return p.to_path_buf();
    }
    let name = match p.file_name() {
        Some(n) => n,
        None => return p.to_path_buf(),
    };
    let cache = std::path::Path::new(cache_dir);
    let candidate = cache.join("mbtiles").join(name);
    if candidate.is_file() {
        return candidate;
    }
    if let Ok(env_dir) = std::env::var("ROBRIX_MAP_DATA_DIR") {
        let candidate = PathBuf::from(env_dir).join("mbtiles").join(name);
        if candidate.is_file() {
            return candidate;
        }
    }
    p.to_path_buf()
}

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

    fn make_config() -> SchedulerConfig {
        SchedulerConfig {
            use_network: true,
            use_local_mbtiles: true,
            max_pending_requests: 2,
            max_local_tile_batch: 10,
            max_tile_retries: 6,
            local_mbtiles_path: "test.mbtiles".to_string(),
            local_tile_cache_dir: "local/tilecache_v5".to_string(),
        }
    }

    #[test]
    fn scheduler_default_visible_empty() {
        let s = TileScheduler::new();
        assert!(s.visible_tiles().is_empty());
    }

    #[test]
    fn on_batch_loaded_clears_local_requested() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 0, y: 0 };
        s.local_requested.insert(k);
        let loaded = HashSet::new();
        s.on_batch_loaded(vec![k], &loaded);
        assert!(!s.local_requested.contains(&k));
        assert!(s.local_missing.contains(&k), "should be marked missing");
    }

    #[test]
    fn on_batch_loaded_with_found_tile() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 0, y: 0 };
        s.local_requested.insert(k);
        let mut loaded = HashSet::new();
        loaded.insert(k);
        s.on_batch_loaded(vec![k], &loaded);
        assert!(!s.local_missing.contains(&k));
    }

    #[test]
    fn on_batch_failed_clears_local_requested() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 0, y: 0 };
        s.local_requested.insert(k);
        s.on_batch_failed(vec![k]);
        assert!(!s.local_requested.contains(&k));
        assert!(!s.local_missing.contains(&k));
    }

    #[test]
    fn on_http_response_returns_tile_key() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 1, y: 2 };
        s.request_to_tile.insert(
            LiveId(42),
            PendingTileRequest {
                tile_key: k,
                endpoint: "https://test.com",
                generation: 7,
            },
        );
        assert_eq!(s.on_http_response(LiveId(42)), Some((k, 7)));
        assert_eq!(s.on_http_response(LiveId(42)), None); // consumed
    }

    #[test]
    fn on_http_error_returns_tile_key() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 1, y: 2 };
        s.request_to_tile.insert(
            LiveId(99),
            PendingTileRequest {
                tile_key: k,
                endpoint: "https://test.com",
                generation: 3,
            },
        );
        assert_eq!(s.on_http_error(LiveId(99)), Some((k, 3)));
        assert_eq!(s.on_http_error(LiveId(99)), None);
    }

    #[test]
    fn reset_clears_all() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 0, y: 0 };
        s.local_requested.insert(k);
        s.local_missing.insert(k);
        s.request_to_tile.insert(
            LiveId(1),
            PendingTileRequest {
                tile_key: k,
                endpoint: "test",
                generation: 1,
            },
        );
        s.reset();
        assert!(s.local_requested.is_empty());
        assert!(s.local_missing.is_empty());
        assert!(s.request_to_tile.is_empty());
    }

    #[test]
    fn clear_missing_resets() {
        let mut s = TileScheduler::new();
        s.local_missing.insert(TileKey { z: 14, x: 0, y: 0 });
        s.local_missing.insert(TileKey { z: 14, x: 1, y: 0 });
        s.clear_missing();
        assert!(s.local_missing.is_empty());
    }

    #[test]
    fn request_id_increments() {
        let mut s = TileScheduler::new();
        let id1 = s.next_request_id;
        // Simulate a schedule call that generates a request
        let _ = s.schedule_single_tile(
            TileKey { z: 14, x: 0, y: 0 },
            0,
            &make_config(),
            1,
            1,
        );
        assert!(s.next_request_id > id1);
    }

    #[test]
    fn schedule_no_action_when_cache_full() {
        let mut s = TileScheduler::new();
        let mut cache = TileCache::new(100);
        // Fill cache with all visible tiles
        let visible = vec![
            TileKey { z: 14, x: 0, y: 0 },
            TileKey { z: 14, x: 1, y: 0 },
        ];
        for k in &visible {
            cache.tiles.insert(
                *k,
                TileEntry {
                    state: TileLoadState::Ready {
                        fill_geometry: None,
                        stroke_geometry: None,
                        feature_count: 5,
                        labels: vec![],
                        pois: vec![],
                    },
                    last_used: 0,
                    attempts: 0,
                },
            );
        }
        s.visible_tiles = visible;
        let config = make_config();
        let actions = s.schedule(&cache, &config, 1);
        assert!(actions.is_empty());
    }

    #[test]
    fn schedule_requests_missing_tiles() {
        let mut s = TileScheduler::new();
        let cache = TileCache::new(100);
        let k = TileKey { z: 14, x: 0, y: 0 };
        s.visible_tiles = vec![k];
        // Network only, no mbtiles
        let mut config = make_config();
        config.use_local_mbtiles = false;
        config.use_network = true;
        let actions = s.schedule(&cache, &config, 1);
        assert!(!actions.is_empty(), "should request missing tile");
    }

    #[test]
    fn schedule_skips_when_nothing_enabled() {
        let mut s = TileScheduler::new();
        let cache = TileCache::new(100);
        s.visible_tiles = vec![TileKey { z: 14, x: 0, y: 0 }];
        let mut config = make_config();
        config.use_local_mbtiles = false;
        config.use_network = false;
        let actions = s.schedule(&cache, &config, 1);
        assert!(actions.is_empty());
    }

    #[test]
    fn schedule_respects_pending_limit() {
        let mut s = TileScheduler::new();
        let mut cache = TileCache::new(100);
        // Add 3 loading tiles
        for i in 0..3 {
            cache.tiles.insert(
                TileKey { z: 14, x: i, y: 0 },
                TileEntry {
                    state: TileLoadState::LoadingNetwork,
                    last_used: 0,
                    attempts: 0,
                },
            );
        }
        s.visible_tiles = (0..5)
            .map(|i| TileKey { z: 14, x: i, y: 0 })
            .collect();
        let mut config = make_config();
        config.use_local_mbtiles = false;
        config.use_network = true;
        config.max_pending_requests = 2;
        let actions = s.schedule(&cache, &config, 1);
        // Should not exceed max pending
        let network_actions = actions
            .iter()
            .filter(|a| matches!(a, TileAction::LoadFromNetwork { .. }))
            .count();
        assert!(network_actions <= config.max_pending_requests);
    }

    #[test]
    fn schedule_doesnt_retry_exhausted() {
        let mut s = TileScheduler::new();
        let mut cache = TileCache::new(100);
        let k = TileKey { z: 14, x: 0, y: 0 };
        // Fail with max attempts
        cache.tiles.insert(
            k,
            TileEntry {
                state: TileLoadState::Failed { retry_after: 0 },
                last_used: 0,
                attempts: 6,
            },
        );
        s.visible_tiles = vec![k];
        let mut config = make_config();
        config.use_local_mbtiles = false;
        config.use_network = true;
        config.max_tile_retries = 6;
        let actions = s.schedule(&cache, &config, 1);
        assert!(actions.is_empty(), "should not retry exhausted tile");
    }

    #[test]
    fn scheduler_is_local_missing_check() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 0, y: 0 };
        assert!(!s.is_local_missing(k));
        s.local_missing.insert(k);
        assert!(s.is_local_missing(k));
    }

    #[test]
    fn scheduler_is_local_requested_check() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 0, y: 0 };
        assert!(!s.is_local_requested(k));
        s.local_requested.insert(k);
        assert!(s.is_local_requested(k));
    }

    #[test]
    fn generation_starts_at_1() {
        let s = TileScheduler::new();
        assert_eq!(s.current_generation(), 1);
    }

    #[test]
    fn reset_generation_increments() {
        let mut s = TileScheduler::new();
        let g1 = s.current_generation();
        s.reset_generation();
        assert_eq!(s.current_generation(), g1 + 1);
    }

    #[test]
    fn reset_generation_wraps_to_1() {
        let mut s = TileScheduler::new();
        s.current_generation = u64::MAX;
        s.reset_generation();
        assert_eq!(s.current_generation(), 1);
    }

    #[test]
    fn zoom_change_bumps_generation() {
        let mut s = TileScheduler::new();
        let mut vp = ViewportState::new(36.8, -1.3, 14.0, 0.0, 20.0);
        vp.set_rect(Rect { pos: dvec2(0.0, 0.0), size: dvec2(1080.0, 1920.0) });
        // First call sets generation_zoom_level
        s.update_visible(&mut vp);
        let g1 = s.current_generation();
        // Change zoom
        let mut vp2 = ViewportState::new(36.8, -1.3, 16.0, 0.0, 20.0);
        vp2.set_rect(Rect { pos: dvec2(0.0, 0.0), size: dvec2(1080.0, 1920.0) });
        s.update_visible(&mut vp2);
        assert!(s.current_generation() > g1, "zoom change should bump generation");
    }

    #[test]
    fn same_zoom_does_not_bump_generation() {
        let mut s = TileScheduler::new();
        let mut vp = ViewportState::new(36.8, -1.3, 14.0, 0.0, 20.0);
        vp.set_rect(Rect { pos: dvec2(0.0, 0.0), size: dvec2(1080.0, 1920.0) });
        s.update_visible(&mut vp);
        let g1 = s.current_generation();
        // Same zoom, different pan
        let mut vp2 = ViewportState::new(37.0, -1.5, 14.0, 0.0, 20.0);
        vp2.set_rect(Rect { pos: dvec2(0.0, 0.0), size: dvec2(1080.0, 1920.0) });
        s.update_visible(&mut vp2);
        assert_eq!(s.current_generation(), g1, "same zoom should not bump generation");
    }

    #[test]
    fn schedule_actions_carry_generation() {
        let mut s = TileScheduler::new();
        let mut vp = ViewportState::new(36.8, -1.3, 14.0, 0.0, 20.0);
        vp.set_rect(Rect { pos: dvec2(0.0, 0.0), size: dvec2(1080.0, 1920.0) });
        s.update_visible(&mut vp);
        let gen = s.current_generation();

        let cache = TileCache::new(100);
        let mut config = make_config();
        config.use_local_mbtiles = false;
        config.use_network = true;
        let actions = s.schedule(&cache, &config, 1);
        for action in &actions {
            match action {
                TileAction::LoadFromNetwork { generation: g, .. } => {
                    assert_eq!(*g, gen);
                }
                TileAction::LoadLocalBatch { generation: g, .. } => {
                    assert_eq!(*g, gen);
                }
                TileAction::LoadFromDiskCache { generation: g, .. } => {
                    assert_eq!(*g, gen);
                }
                _ => {}
            }
        }
    }

    #[test]
    fn http_response_includes_generation() {
        let mut s = TileScheduler::new();
        let k = TileKey { z: 14, x: 1, y: 2 };
        s.request_to_tile.insert(
            LiveId(10),
            PendingTileRequest {
                tile_key: k,
                endpoint: "https://test.com",
                generation: 5,
            },
        );
        let (key, gen) = s.on_http_response(LiveId(10)).unwrap();
        assert_eq!(key, k);
        assert_eq!(gen, 5);
    }

    #[test]
    fn update_visible_skips_when_not_dirty() {
        let mut s = TileScheduler::new();
        let mut vp = ViewportState::new(36.8, -1.3, 14.0, 0.0, 20.0);
        vp.set_rect(Rect { pos: dvec2(0.0, 0.0), size: dvec2(1080.0, 1920.0) });
        // First call: dirty=true, computes visible tiles
        let changed = s.update_visible(&mut vp);
        assert!(changed, "first call should compute and return changed");
        assert!(!vp.dirty, "dirty should be cleared after update");
        assert!(!s.visible_tiles().is_empty());
        
        // Second call without changes: dirty=false, should skip recomputation
        let changed2 = s.update_visible(&mut vp);
        assert!(!changed2, "should skip when not dirty");
    }

    #[test]
    fn update_visible_recomputes_when_dirty() {
        let mut s = TileScheduler::new();
        let mut vp = ViewportState::new(36.8, -1.3, 14.0, 0.0, 20.0);
        vp.set_rect(Rect { pos: dvec2(0.0, 0.0), size: dvec2(1080.0, 1920.0) });
        s.update_visible(&mut vp);
        assert!(!vp.dirty);
        
        // Apply a drag to set dirty
        vp.apply_drag(dvec2(100.0, 0.0));
        assert!(vp.dirty, "drag should set dirty");
        
        // Update should recompute
        let changed = s.update_visible(&mut vp);
        assert!(changed, "should recompute when dirty");
        assert!(!vp.dirty, "dirty should be cleared");
    }
}