implement session cache

src/list/cache.rs

@@ -0,0 +1,68 @@
+use anyhow::{Result, bail};
+use std::{collections::HashSet, path::PathBuf};
+use tokio::fs;
+
+pub struct Cache(Option<PathBuf>);
+
+impl Cache {
+    pub async fn from_path(path: Option<PathBuf>) -> Result<Self> {
+        Ok(Self(match path {
+            Some(p) => {
+                init_file(&p).await?;
+                Some(p)
+            }
+            None => None,
+        }))
+    }
+    pub async fn read(&self) -> Result<Option<String>> {
+        Ok(if let Some(ref p) = self.0 {
+            init_file(p).await?;
+            Some(fs::read_to_string(p).await?)
+        } else {
+            None
+        })
+    }
+    pub async fn allow(&self, rule: &str) -> Result<()> {
+        if let Some(ref p) = self.0 {
+            init_file(p).await?;
+            let mut rules = HashSet::new();
+            let lines = fs::read_to_string(p).await?;
+            for line in lines.lines() {
+                rules.insert(line);
+            }
+            rules.insert(rule);
+            fs::write(p, rules.into_iter().collect::<Vec<_>>().join("\n")).await?;
+        }
+        Ok(())
+    }
+    pub async fn block(&self, rule: &str) -> Result<()> {
+        if let Some(ref p) = self.0 {
+            init_file(p).await?;
+            let mut rules = HashSet::new();
+            let lines = fs::read_to_string(p).await?;
+            for line in lines.lines() {
+                if line != rule {
+                    rules.insert(line);
+                }
+            }
+            fs::write(p, rules.into_iter().collect::<Vec<_>>().join("\n")).await?;
+        }
+        Ok(())
+    }
+}
+
+/// Make sure that cache file is always exist (e.g. user may remove it when the daemon is running)
+async fn init_file(path: &PathBuf) -> Result<()> {
+    if path.exists() {
+        if path.is_file() {
+            return Ok(());
+        } else {
+            bail!(
+                "Cache path `{}` exist but it is not a file!",
+                path.to_string_lossy()
+            )
+        }
+    }
+    fs::write(path, "").await?;
+    Ok(())
+}