Cargo.lock

@@ -142,6 +142,7 @@ dependencies = [
  "iana-time-zone",
  "js-sys",
  "num-traits",
+ "serde",
  "wasm-bindgen",
  "windows-link",
 ]

Cargo.toml

@@ -9,7 +9,7 @@ toml = "0.8"
 # Only keep one of blocking+async if all features converted
 reqwest = { version = "0.12", features = ["json", "rustls-tls" ] }
 dirs = "5"
-chrono = "0.4"
+chrono = { version = "0.4", features = ["serde"] }
 serde_json = "1.0"
 chrono-tz = "0.8"
 tokio = { version = "1.37", features = ["full"] }

src/cache.rs

@@ -0,0 +1,52 @@
+use serde::{Deserialize, Serialize};
+use std::{
+    fs,
+    path::PathBuf,
+    time::{SystemTime, UNIX_EPOCH},
+};
+
+#[derive(Serialize, Deserialize)]
+pub struct Cache<T> {
+    pub timestamp: u64,
+    pub data: T,
+}
+
+fn get_cache_path(report_type: &str) -> PathBuf {
+    let home = std::env::var("HOME").expect("HOME not set");
+    let cache_dir = PathBuf::from(format!("{}/.local/state/trmnl", home));
+    let _ = fs::create_dir_all(&cache_dir);
+    cache_dir.join(format!("{}.json", report_type))
+}
+
+use serde::de::DeserializeOwned;
+pub fn load_cache<T: Serialize + DeserializeOwned>(
+    report_type: &str,
+    expiry_secs: u64,
+) -> Option<T> {
+    let path = get_cache_path(report_type);
+    let contents = fs::read_to_string(&path).ok()?;
+    let parsed: Cache<T> = serde_json::from_str(&contents).ok()?;
+    let now = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap()
+        .as_secs();
+    if now - parsed.timestamp <= expiry_secs {
+        println!("(using cached {} report)", report_type);
+        Some(parsed.data)
+    } else {
+        None
+    }
+}
+
+pub fn save_cache<T: Serialize>(report_type: &str, data: &T) {
+    let path = get_cache_path(report_type);
+    let to_save = Cache {
+        timestamp: SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .unwrap()
+            .as_secs(),
+        data: data,
+    };
+    let json = serde_json::to_string_pretty(&to_save).unwrap();
+    let _ = fs::write(path, json);
+}

src/calendar.rs

@@ -1,8 +1,10 @@
 use chrono::{DateTime, FixedOffset, NaiveDate, Offset, TimeZone, Utc};
 use ical::IcalParser;
 use rrule::{RRule, RRuleSet, Unvalidated};
+use serde::{Deserialize, Serialize};
 use std::error::Error;
 
+#[derive(Serialize, Deserialize)]
 pub struct CalendarEventSummary {
     pub start: Option<DateTime<FixedOffset>>,
     pub summary: String,

src/config.rs

@@ -5,6 +5,9 @@ use std::path::PathBuf;
 
 #[derive(Debug, Deserialize)]
 pub struct Config {
+    pub cache_weather_secs: Option<u64>,
+    pub cache_pollen_secs: Option<u64>,
+    pub cache_calendar_secs: Option<u64>,
     pub weather_api_key: String,
     pub pollen_api_key: String,
     pub calendar_api_key: String,

src/main.rs

@@ -1,3 +1,4 @@
+mod cache;
 mod calendar;
 mod config;
 mod pollen;
@@ -20,12 +21,21 @@ async fn main() {
         }
     };
 
+    // Weather - with cache
+    let cache_weather_secs = config.cache_weather_secs.unwrap_or(300);
     let weather: Option<WeatherSummary> =
-        match fetch_weather(&config.location, &config.weather_api_key).await {
-            Ok(data) => Some(data),
-            Err(e) => {
-                eprintln!("Failed to fetch weather: {e}");
-                None
+        if let Some(w) = cache::load_cache::<WeatherSummary>("weather", cache_weather_secs) {
+            Some(w)
+        } else {
+            match fetch_weather(&config.location, &config.weather_api_key).await {
+                Ok(data) => {
+                    cache::save_cache("weather", &data);
+                    Some(data)
+                }
+                Err(e) => {
+                    eprintln!("Failed to fetch weather: {e}");
+                    None
+                }
             }
         };
     let (_lat, _lon) = if weather.is_some() {
@@ -66,7 +76,19 @@ async fn main() {
         println!("Weather: N/A");
     }
 
-    match fetch_pollen_api(&config.pollen_zip).await {
+    // Pollen - with cache
+    let cache_pollen_secs = config.cache_pollen_secs.unwrap_or(300);
+    match if let Some(p) = cache::load_cache::<pollen::PollenSummary>("pollen", cache_pollen_secs) {
+        Ok(p)
+    } else {
+        match fetch_pollen_api(&config.pollen_zip).await {
+            Ok(data) => {
+                cache::save_cache("pollen", &data);
+                Ok(data)
+            }
+            Err(e) => Err(e),
+        }
+    } {
         Ok(p) => {
             if let Ok(dt) = DateTime::parse_from_rfc3339(&p.forecast_date) {
                 match config.timezone.parse::<Tz>() {
@@ -110,16 +132,29 @@ async fn main() {
         }
     }
 
-    println!();
-    println!("Upcoming calendar events:");
+    // Calendar - with cache
+    let cache_calendar_secs = config.cache_calendar_secs.unwrap_or(300);
+    println!("\nUpcoming calendar events:");
 
-    match fetch_next_events(
-        &config.calendar_url,
-        config.calendar_event_count,
-        &config.timezone,
-    )
-    .await
+    match if let Some(events) =
+        cache::load_cache::<Vec<calendar::CalendarEventSummary>>("calendar", cache_calendar_secs)
     {
+        Ok(events)
+    } else {
+        match fetch_next_events(
+            &config.calendar_url,
+            config.calendar_event_count,
+            &config.timezone,
+        )
+        .await
+        {
+            Ok(data) => {
+                cache::save_cache("calendar", &data);
+                Ok(data)
+            }
+            Err(e) => Err(e),
+        }
+    } {
         Ok(events) if !events.is_empty() => {
             for (i, event) in events.iter().enumerate() {
                 let day = event

src/pollen.rs

@@ -1,4 +1,4 @@
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::error::Error;
 
@@ -34,11 +34,13 @@ struct Trigger {
     genus: String,
 }
 
+#[derive(Serialize, Deserialize)]
 pub struct PollenPeriod {
     pub index: f32,
     pub triggers: Vec<String>,
 }
 
+#[derive(Serialize, Deserialize)]
 pub struct PollenSummary {
     pub location: String,
     pub forecast_date: String,

src/weather.rs

@@ -1,4 +1,4 @@
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 use std::error::Error;
 
 #[allow(dead_code)]
@@ -72,6 +72,7 @@ pub struct OneCallResult {
     pub daily: Vec<WeatherDaily>,
 }
 
+#[derive(Serialize, Deserialize)]
 pub struct WeatherSummary {
     pub temp: String,
     pub current_desc: String,