Fix cache bug

Fix bug where a potentially incorrect resolution would be assumed.

src/cache/cache.rs

@@ -0,0 +1,96 @@
+use std::fs;
+use std::io::{BufReader, BufWriter};
+use std::path::Path;
+
+use anyhow::Context;
+use serde::{Deserialize, Serialize};
+
+use crate::cli::Resolution;
+use crate::os::Os;
+
+use super::CacheLine;
+
+const FILE_NAME: &'static str = "cache.json";
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct Cache {
+    day: Option<CacheLine>,
+    hist_90: Option<CacheLine>,
+    hist_day: Option<CacheLine>,
+}
+
+impl Cache {
+    pub fn load() -> Option<Self> {
+        let config_opt = Os::get_current()?.get_config_path();
+        let mut config_path = match config_opt {
+            Ok(k) => k,
+            Err(e) => {
+                eprintln!("Failed to locate config dir: {:?}", e);
+                return None;
+            }
+        };
+        if let Err(e) = fs::create_dir_all(&config_path) {
+            eprintln!("Failed to create config dir: {:?}", e);
+            return None;
+        }
+        config_path.push(FILE_NAME);
+        if !config_path.try_exists().unwrap_or_default() {
+            return Some(Self {
+                day: None,
+                hist_90: None,
+                hist_day: None,
+            });
+        }
+
+        match Self::read_config(&config_path) {
+            Ok(k) => Some(k),
+            Err(e) => {
+                eprintln!("Config path is invalid, or cannot be created: {:?}", e);
+                None
+            }
+        }
+    }
+
+    pub fn get_cache_line(&self, resolution: Resolution) -> Option<&CacheLine> {
+        match resolution {
+            Resolution::TODAY => self.day.as_ref(),
+            Resolution::HistDays90 => self.hist_90.as_ref(),
+            Resolution::HistDay => self.hist_day.as_ref(),
+        }
+    }
+
+    pub fn set_cache_line(&mut self, resolution: Resolution, cache_line: CacheLine) {
+        let cache_line_opt = Some(cache_line);
+        match resolution {
+            Resolution::TODAY => self.day = cache_line_opt,
+            Resolution::HistDays90 => self.hist_90 = cache_line_opt,
+            Resolution::HistDay => self.hist_day = cache_line_opt,
+        }
+    }
+
+    pub fn save(&self) -> anyhow::Result<()> {
+        let mut config_path = Os::get_current()
+            .context("Failed to get config home")?
+            .get_config_path()?;
+        fs::create_dir_all(&config_path)?;
+
+        config_path.push(FILE_NAME);
+
+        let file = fs::File::options()
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open(&config_path)?;
+
+        let writer = BufWriter::new(file);
+        serde_json::to_writer(writer, self)?;
+
+        Ok(())
+    }
+
+    fn read_config(path: &Path) -> anyhow::Result<Self> {
+        let file = fs::File::open(path)?;
+        let reader = BufReader::new(file);
+        Ok(serde_json::from_reader(reader)?)
+    }
+}