First one-shot pass

src/store/json_store.rs

@@ -0,0 +1,75 @@
+use std::fs;
+use std::io::Write;
+use std::path::PathBuf;
+
+use anyhow::Result;
+use serde::{de::DeserializeOwned, Serialize};
+
+use crate::store::schema::{KeyStatsData, LessonHistoryData, ProfileData};
+
+pub struct JsonStore {
+    base_dir: PathBuf,
+}
+
+impl JsonStore {
+    pub fn new() -> Result<Self> {
+        let base_dir = dirs::data_dir()
+            .unwrap_or_else(|| PathBuf::from("."))
+            .join("keydr");
+        fs::create_dir_all(&base_dir)?;
+        Ok(Self { base_dir })
+    }
+
+    fn file_path(&self, name: &str) -> PathBuf {
+        self.base_dir.join(name)
+    }
+
+    fn load<T: DeserializeOwned + Default>(&self, name: &str) -> T {
+        let path = self.file_path(name);
+        if path.exists() {
+            match fs::read_to_string(&path) {
+                Ok(content) => serde_json::from_str(&content).unwrap_or_default(),
+                Err(_) => T::default(),
+            }
+        } else {
+            T::default()
+        }
+    }
+
+    fn save<T: Serialize>(&self, name: &str, data: &T) -> Result<()> {
+        let path = self.file_path(name);
+        let tmp_path = path.with_extension("tmp");
+
+        let json = serde_json::to_string_pretty(data)?;
+        let mut file = fs::File::create(&tmp_path)?;
+        file.write_all(json.as_bytes())?;
+        file.sync_all()?;
+
+        fs::rename(&tmp_path, &path)?;
+        Ok(())
+    }
+
+    pub fn load_profile(&self) -> ProfileData {
+        self.load("profile.json")
+    }
+
+    pub fn save_profile(&self, data: &ProfileData) -> Result<()> {
+        self.save("profile.json", data)
+    }
+
+    pub fn load_key_stats(&self) -> KeyStatsData {
+        self.load("key_stats.json")
+    }
+
+    pub fn save_key_stats(&self, data: &KeyStatsData) -> Result<()> {
+        self.save("key_stats.json", data)
+    }
+
+    pub fn load_lesson_history(&self) -> LessonHistoryData {
+        self.load("lesson_history.json")
+    }
+
+    pub fn save_lesson_history(&self, data: &LessonHistoryData) -> Result<()> {
+        self.save("lesson_history.json", data)
+    }
+}