556 lines
19 KiB
Rust
556 lines
19 KiB
Rust
//! Maps retrieval and caching.
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//!
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//! This module provides a task that keeps maps up-to-date using a maps-specific refresh interval.
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//! It stores all the maps as [`DynamicImage`]s in memory.
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use std::collections::HashMap;
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use std::f64::consts::PI;
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use std::sync::{Arc, Mutex};
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use chrono::serde::ts_seconds;
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use chrono::{DateTime, Duration, Utc};
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use image::{DynamicImage, GenericImage, GenericImageView, ImageFormat, Pixel, Rgb, Rgba};
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use reqwest::Url;
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use rocket::serde::Serialize;
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use rocket::tokio;
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use rocket::tokio::time::sleep;
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use crate::forecast::Metric;
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use crate::position::Position;
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/// A handle to access the in-memory cached maps.
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pub(crate) type MapsHandle = Arc<Mutex<Maps>>;
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/// A histogram mapping map key colors to occurences/counts.
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type MapKeyHistogram = HashMap<Rgb<u8>, u32>;
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/// The Buienradar map key used for determining the score of a coordinate by mapping its color.
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///
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/// Note that the actual score starts from 1, not 0 as per this array.
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#[rustfmt::skip]
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const MAP_KEY: [[u8; 3]; 10] = [
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[ 73, 218, 33],
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[ 48, 210, 0],
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[255, 248, 139],
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[255, 246, 66],
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[253, 187, 49],
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[253, 142, 36],
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[252, 16, 62],
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[150, 10, 51],
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[166, 109, 188],
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[179, 48, 161],
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];
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/// The Buienradar map sample size.
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///
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/// Determiess the number of pixels in width/height that is samples around the sampling coordinate.
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const MAP_SAMPLE_SIZE: [u32; 2] = [11, 11];
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/// The interval between map refreshes (in seconds).
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const REFRESH_INTERVAL: tokio::time::Duration = tokio::time::Duration::from_secs(60);
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/// The base URL for retrieving the pollen maps from Buienradar.
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const POLLEN_BASE_URL: &str =
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"https://image.buienradar.nl/2.0/image/sprite/WeatherMapPollenRadarHourlyNL\
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?width=820&height=988&extension=png&renderBackground=False&renderBranding=False\
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&renderText=False&history=0&forecast=24&skip=0";
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/// The interval for retrieving pollen maps.
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///
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/// The endpoint provides a map for every hour, 24 in total.
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const POLLEN_INTERVAL: i64 = 3_600;
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/// The number of pollen maps retained.
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const POLLEN_MAP_COUNT: u32 = 24;
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/// The number of seconds each pollen map is for.
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const POLLEN_MAP_INTERVAL: i64 = 3_600;
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/// The position reference points for the pollen map.
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///
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/// Maps the gecoded positions of two reference points as follows:
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/// * Latitude and longitude of Vlissingen to its y- and x-position
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/// * Latitude of Lauwersoog to its y-position and longitude of Enschede to its x-position
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const POLLEN_MAP_REF_POINTS: [(Position, (u32, u32)); 2] = [
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(Position::new(51.44, 3.57), (745, 84)), // Vlissingen
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(Position::new(53.40, 6.90), (111, 694)), // Lauwersoog (lat/y) and Enschede (lon/x)
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];
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/// The base URL for retrieving the UV index maps from Buienradar.
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const UVI_BASE_URL: &str = "https://image.buienradar.nl/2.0/image/sprite/WeatherMapUVIndexNL\
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?width=820&height=988&extension=png&&renderBackground=False&renderBranding=False\
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&renderText=False&history=0&forecast=5&skip=0";
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/// The interval for retrieving UV index maps.
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///
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/// The endpoint provides a map for every day, 5 in total.
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const UVI_INTERVAL: i64 = 24 * 3_600;
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/// The number of UV index maps retained.
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const UVI_MAP_COUNT: u32 = 5;
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/// The number of seconds each UV index map is for.
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const UVI_MAP_INTERVAL: i64 = 24 * 3_600;
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/// The position reference points for the UV index map.
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const UVI_MAP_REF_POINTS: [(Position, (u32, u32)); 2] = POLLEN_MAP_REF_POINTS;
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/// The `MapsRefresh` trait is used to reduce the time a lock needs to be held when updating maps.
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///
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/// When refreshing maps, the lock only needs to be held when checking whether a refresh is
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/// necessary and when the new maps have been retrieved and can be updated.
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trait MapsRefresh {
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/// Determines whether the pollen maps need to be refreshed.
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fn needs_pollen_refresh(&self) -> bool;
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/// Determines whether the UV index maps need to be refreshed.
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fn needs_uvi_refresh(&self) -> bool;
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/// Determines whether the pollen maps are stale.
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fn is_pollen_stale(&self) -> bool;
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/// Determines whether the UV index maps are stale.
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fn is_uvi_stale(&self) -> bool;
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/// Updates the pollen maps.
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fn set_pollen(&self, result: Option<(DynamicImage, DateTime<Utc>)>);
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/// Updates the UV index maps.
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fn set_uvi(&self, result: Option<(DynamicImage, DateTime<Utc>)>);
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}
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/// Container type for all in-memory cached maps.
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#[derive(Debug)]
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pub(crate) struct Maps {
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/// The pollen maps (from Buienradar).
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pub(crate) pollen: Option<DynamicImage>,
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/// The timestamp the pollen maps were last refreshed.
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pollen_stamp: DateTime<Utc>,
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/// The UV index maps (from Buienradar).
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pub(crate) uvi: Option<DynamicImage>,
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/// The timestamp the UV index maps were last refreshed.
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uvi_stamp: DateTime<Utc>,
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}
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impl Maps {
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/// Creates a new maps cache.
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///
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/// It contains an [`DynamicImage`] per maps type, if downloaded, and the timestamp of the last
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/// update.
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pub(crate) fn new() -> Self {
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let now = Utc::now();
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Self {
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pollen: None,
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pollen_stamp: now,
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uvi: None,
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uvi_stamp: now,
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}
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}
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/// Returns a current pollen map that marks the provided position.
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///
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/// This returns [`None`] if the maps are not in the cache yet, there is no matching map for
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/// the current moment or if the provided position is not within the bounds of the map.
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pub(crate) fn pollen_mark(&self, position: Position) -> Option<DynamicImage> {
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self.pollen.as_ref().and_then(|maps| {
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let map = map_at(
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maps,
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self.pollen_stamp,
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POLLEN_MAP_INTERVAL,
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POLLEN_MAP_COUNT,
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Utc::now(),
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)?;
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let coords = project(&map, POLLEN_MAP_REF_POINTS, position)?;
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Some(mark(map, coords))
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})
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}
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/// Samples the pollen maps for the given position.
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///
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/// This returns [`None`] if the maps are not in the cache yet.
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/// Otherwise, it returns [`Some`] with a list of pollen sample, one for each map
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/// in the series of maps.
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pub(crate) fn pollen_samples(&self, position: Position) -> Option<Vec<Sample>> {
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self.pollen.as_ref().and_then(|maps| {
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let map = maps.view(0, 0, maps.width() / UVI_MAP_COUNT, maps.height());
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let coords = project(&*map, POLLEN_MAP_REF_POINTS, position)?;
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sample(
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maps,
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self.pollen_stamp,
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POLLEN_MAP_INTERVAL,
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POLLEN_MAP_COUNT,
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coords,
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)
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})
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}
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/// Returns a current UV index map that marks the provided position.
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///
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/// This returns [`None`] if the maps are not in the cache yet, there is no matching map for
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/// the current moment or if the provided position is not within the bounds of the map.
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pub(crate) fn uvi_mark(&self, position: Position) -> Option<DynamicImage> {
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self.uvi.as_ref().and_then(|maps| {
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let map = map_at(
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maps,
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self.uvi_stamp,
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UVI_MAP_INTERVAL,
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UVI_MAP_COUNT,
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Utc::now(),
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)?;
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let coords = project(&map, POLLEN_MAP_REF_POINTS, position)?;
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Some(mark(map, coords))
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})
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}
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/// Samples the UV index maps for the given position.
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///
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/// This returns [`None`] if the maps are not in the cache yet.
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/// Otherwise, it returns [`Some`] with a list of UV index sample, one for each map
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/// in the series of maps.
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pub(crate) fn uvi_samples(&self, position: Position) -> Option<Vec<Sample>> {
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self.uvi.as_ref().and_then(|maps| {
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let map = maps.view(0, 0, maps.width() / UVI_MAP_COUNT, maps.height());
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let coords = project(&*map, UVI_MAP_REF_POINTS, position)?;
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sample(
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maps,
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self.uvi_stamp,
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UVI_MAP_INTERVAL,
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UVI_MAP_COUNT,
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coords,
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)
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})
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}
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}
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impl MapsRefresh for MapsHandle {
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fn is_pollen_stale(&self) -> bool {
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let maps = self.lock().expect("Maps handle mutex was poisoned");
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Utc::now().signed_duration_since(maps.pollen_stamp)
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> Duration::seconds(POLLEN_MAP_COUNT as i64 * POLLEN_MAP_INTERVAL)
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}
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fn is_uvi_stale(&self) -> bool {
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let maps = self.lock().expect("Maps handle mutex was poisoned");
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Utc::now().signed_duration_since(maps.uvi_stamp)
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> Duration::seconds(UVI_MAP_COUNT as i64 * UVI_MAP_INTERVAL)
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}
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fn needs_pollen_refresh(&self) -> bool {
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let maps = self.lock().expect("Maps handle mutex was poisoned");
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maps.pollen.is_none()
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|| Utc::now()
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.signed_duration_since(maps.pollen_stamp)
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.num_seconds()
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> POLLEN_INTERVAL
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}
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fn needs_uvi_refresh(&self) -> bool {
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let maps = self.lock().expect("Maps handle mutex was poisoned");
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maps.uvi.is_none()
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|| Utc::now()
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.signed_duration_since(maps.uvi_stamp)
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.num_seconds()
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> UVI_INTERVAL
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}
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fn set_pollen(&self, result: Option<(DynamicImage, DateTime<Utc>)>) {
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if result.is_some() || self.is_pollen_stale() {
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let mut maps = self.lock().expect("Maps handle mutex was poisoned");
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if let Some((pollen, pollen_stamp)) = result {
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maps.pollen = Some(pollen);
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maps.pollen_stamp = pollen_stamp
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} else {
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maps.pollen = None
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}
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}
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}
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fn set_uvi(&self, result: Option<(DynamicImage, DateTime<Utc>)>) {
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if result.is_some() || self.is_uvi_stale() {
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let mut maps = self.lock().expect("Maps handle mutex was poisoned");
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if let Some((uvi, uvi_stamp)) = result {
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maps.uvi = Some(uvi);
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maps.uvi_stamp = uvi_stamp
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} else {
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maps.uvi = None
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}
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}
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}
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}
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/// A Buienradar map sample.
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///
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/// This represents a value at a given time.
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#[derive(Clone, Debug, Serialize)]
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#[serde(crate = "rocket::serde")]
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pub(crate) struct Sample {
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/// The time(stamp) of the forecast.
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#[serde(serialize_with = "ts_seconds::serialize")]
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pub(crate) time: DateTime<Utc>,
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/// The forecasted score.
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///
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/// A value in the range `1..=10`.
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#[serde(rename(serialize = "value"))]
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pub(crate) score: u8,
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}
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/// Builds a scoring histogram for the map key.
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fn map_key_histogram() -> MapKeyHistogram {
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MAP_KEY
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.into_iter()
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.fold(HashMap::new(), |mut hm, channels| {
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hm.insert(Rgb::from(channels), 0);
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hm
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})
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}
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/// Samples the provided maps at the given (map-relative) coordinates and starting timestamp.
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/// It assumes the provided coordinates are within bounds of at least one map.
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/// The interval is the number of seconds the timestamp is bumped for each map.
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///
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/// Returns [`None`] if it encounters no known colors in any of the samples.
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fn sample<I: GenericImageView<Pixel = Rgba<u8>>>(
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maps: &I,
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stamp: DateTime<Utc>,
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interval: i64,
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count: u32,
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coords: (u32, u32),
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) -> Option<Vec<Sample>> {
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let (x, y) = coords;
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let width = maps.width() / count;
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let height = maps.height();
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let max_sample_width = (width - x).min(MAP_SAMPLE_SIZE[0]);
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let max_sample_height = (height - y).min(MAP_SAMPLE_SIZE[1]);
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let mut samples = Vec::with_capacity(count as usize);
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let mut time = stamp;
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let mut offset = 0;
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while offset < maps.width() {
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let map = maps.view(
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x.saturating_sub(MAP_SAMPLE_SIZE[0] / 2) + offset,
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y.saturating_sub(MAP_SAMPLE_SIZE[1] / 2),
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max_sample_width,
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max_sample_height,
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);
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let histogram = map
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.pixels()
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.fold(map_key_histogram(), |mut h, (_px, _py, color)| {
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h.entry(color.to_rgb()).and_modify(|count| *count += 1);
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h
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});
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let (max_color, &count) = histogram
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.iter()
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.max_by_key(|(_color, count)| *count)
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.expect("Map key is never empty");
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if count == 0 {
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return None;
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}
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let score = MAP_KEY
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.iter()
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.position(|&color| &Rgb::from(color) == max_color)
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.map(|score| score + 1) // Scores go from 1..=10, not 0..=9!
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.expect("Maximum color is always a map key color") as u8;
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samples.push(Sample { time, score });
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time = time + chrono::Duration::seconds(interval as i64);
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offset += width;
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}
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Some(samples)
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}
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/// Retrieves an image from the provided URL.
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///
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/// This returns [`None`] if it fails in either performing the request, parsing the `Last-Modified`
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/// reponse HTTP header, retrieving the bytes from the image or loading and the decoding the data
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/// into [`DynamicImage`].
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async fn retrieve_image(url: Url) -> Option<(DynamicImage, DateTime<Utc>)> {
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// TODO: Handle or log errors!
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let response = reqwest::get(url).await.ok()?;
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let mtime = response
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.headers()
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.get(reqwest::header::LAST_MODIFIED)
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.and_then(|dt| dt.to_str().ok())
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.map(chrono::DateTime::parse_from_rfc2822)?
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.map(DateTime::<Utc>::from)
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.ok()?;
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let bytes = response.bytes().await.ok()?;
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tokio::task::spawn_blocking(move || {
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if let Ok(image) = image::load_from_memory_with_format(&bytes, ImageFormat::Png) {
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Some((image, mtime))
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} else {
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None
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}
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})
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.await
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.ok()?
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}
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/// Retrieves the pollen maps from Buienradar.
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///
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/// See [`POLLEN_BASE_URL`] for the base URL and [`retrieve_image`] for the retrieval function.
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async fn retrieve_pollen_maps() -> Option<(DynamicImage, DateTime<Utc>)> {
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let timestamp = format!("{}", chrono::Local::now().format("%y%m%d%H%M"));
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let mut url = Url::parse(POLLEN_BASE_URL).unwrap();
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url.query_pairs_mut().append_pair("timestamp", ×tamp);
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println!("🔽 Refreshing pollen maps from: {}", url);
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retrieve_image(url).await
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}
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/// Retrieves the UV index maps from Buienradar.
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///
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/// See [`UVI_BASE_URL`] for the base URL and [`retrieve_image`] for the retrieval function.
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async fn retrieve_uvi_maps() -> Option<(DynamicImage, DateTime<Utc>)> {
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let timestamp = format!("{}", chrono::Local::now().format("%y%m%d%H%M"));
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let mut url = Url::parse(UVI_BASE_URL).unwrap();
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url.query_pairs_mut().append_pair("timestamp", ×tamp);
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println!("🔽 Refreshing UV index maps from: {}", url);
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retrieve_image(url).await
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}
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/// Returns the map for the given instant.
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///
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/// This returns [`None`] if `instant` is too far in the future with respect to the number of
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/// cached maps.
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fn map_at(
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maps: &DynamicImage,
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maps_stamp: DateTime<Utc>,
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interval: i64,
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count: u32,
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instant: DateTime<Utc>,
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) -> Option<DynamicImage> {
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let duration = instant.signed_duration_since(maps_stamp);
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let offset = (duration.num_seconds() / interval) as u32;
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// Check if out of bounds.
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if offset >= count {
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return None;
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}
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let width = maps.width() / count;
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Some(maps.crop_imm(offset * width, 0, width, maps.height()))
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}
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/// Marks the provided coordinates on the map using a horizontal and vertical line.
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fn mark(mut map: DynamicImage, coords: (u32, u32)) -> DynamicImage {
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let (x, y) = coords;
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for py in 0..map.height() {
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map.put_pixel(x, py, Rgba::from([0x00, 0x00, 0x00, 0x70]));
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}
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for px in 0..map.width() {
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map.put_pixel(px, y, Rgba::from([0x00, 0x00, 0x00, 0x70]));
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}
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map
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}
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/// Projects the provided geocoded position to a coordinate on a map.
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///
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/// This uses two reference points and a Mercator projection on the y-coordinates of those points
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/// to calculate how the map scales with respect to the provided position.
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///
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/// Returns [`None`] if the resulting coordinate is not within the bounds of the map.
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fn project<I: GenericImageView>(
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map: &I,
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ref_points: [(Position, (u32, u32)); 2],
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pos: Position,
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) -> Option<(u32, u32)> {
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// Get the data from the reference points.
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let (ref1, (ref1_y, ref1_x)) = ref_points[0];
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let (ref2, (ref2_y, ref2_x)) = ref_points[1];
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// For the x-coordinate, use a linear scale.
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|
let scale_x = ((ref2_x - ref1_x) as f64) / (ref2.lon_as_rad() - ref1.lon_as_rad());
|
|
let x = ((pos.lon_as_rad() - ref1.lon_as_rad()) * scale_x + ref1_x as f64).round() as u32;
|
|
|
|
// For the y-coordinate, use a Mercator-projected scale.
|
|
let mercator_y = |lat: f64| (lat / 2.0 + PI / 4.0).tan().ln();
|
|
let ref1_merc_y = mercator_y(ref1.lat_as_rad());
|
|
let ref2_merc_y = mercator_y(ref2.lat_as_rad());
|
|
let scale_y = ((ref1_y - ref2_y) as f64) / (ref2_merc_y - ref1_merc_y);
|
|
let y = ((ref2_merc_y - mercator_y(pos.lat_as_rad())) * scale_y + ref2_y as f64).round() as u32;
|
|
|
|
if map.in_bounds(x, y) {
|
|
Some((x, y))
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Returns the data of a map with a crosshair drawn on it for the given position.
|
|
///
|
|
/// The map that is used is determined by the provided metric.
|
|
pub(crate) async fn mark_map(
|
|
position: Position,
|
|
metric: Metric,
|
|
maps_handle: &MapsHandle,
|
|
) -> Option<Vec<u8>> {
|
|
use std::io::Cursor;
|
|
|
|
let maps_handle = Arc::clone(maps_handle);
|
|
tokio::task::spawn_blocking(move || {
|
|
let maps = maps_handle.lock().expect("Maps handle lock was poisoned");
|
|
let image = match metric {
|
|
Metric::PAQI => maps.pollen_mark(position),
|
|
Metric::Pollen => maps.pollen_mark(position),
|
|
Metric::UVI => maps.uvi_mark(position),
|
|
_ => return None, // Unsupported metric
|
|
}?;
|
|
drop(maps);
|
|
|
|
// Encode the image as PNG image data.
|
|
let mut image_data = Cursor::new(Vec::new());
|
|
image
|
|
.write_to(
|
|
&mut image_data,
|
|
image::ImageOutputFormat::from(image::ImageFormat::Png),
|
|
)
|
|
.ok()?;
|
|
|
|
Some(image_data.into_inner())
|
|
})
|
|
.await
|
|
.ok()
|
|
.flatten()
|
|
}
|
|
|
|
/// Runs a loop that keeps refreshing the maps when necessary.
|
|
///
|
|
/// Use [`MapsRefresh`] trait methods on `maps_handle` to check whether each maps type needs to be
|
|
/// refreshed and uses its retrieval function to update it if necessary.
|
|
pub(crate) async fn run(maps_handle: MapsHandle) {
|
|
loop {
|
|
println!("🕔 Refreshing the maps (if necessary)...");
|
|
|
|
if maps_handle.needs_pollen_refresh() {
|
|
let result = retrieve_pollen_maps().await;
|
|
maps_handle.set_pollen(result);
|
|
}
|
|
|
|
if maps_handle.needs_uvi_refresh() {
|
|
let result = retrieve_uvi_maps().await;
|
|
maps_handle.set_uvi(result);
|
|
}
|
|
|
|
sleep(REFRESH_INTERVAL).await;
|
|
}
|
|
}
|