add persistent state

src/state.rs

@@ -0,0 +1,108 @@
+use std::{collections::HashMap, io::ErrorKind};
+
+use log::{info, error};
+use tokio::{fs::File, io::{AsyncReadExt, AsyncWriteExt}};
+
+use crate::{DownloadableFile, storage_dir};
+
+const STATE_FILE_NAME: &str = "files.json";
+
+pub(crate) mod timestamp {
+    use core::fmt;
+
+    use serde::{Serializer, Deserializer, de::Visitor};
+    use time::OffsetDateTime;
+
+    pub(crate) fn serialize<S: Serializer>(time: &OffsetDateTime, ser: S) -> Result<S::Ok, S::Error> {
+        ser.serialize_i64(time.unix_timestamp())
+    }
+
+    struct I64Visitor;
+
+    impl<'de> Visitor<'de> for I64Visitor {
+        type Value = i64;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            write!(formatter, "a signed integer")
+        }
+
+        fn visit_i64<E>(self, v: i64) -> Result<Self::Value, E> {
+            Ok(v)
+        }
+    }
+
+    pub(crate) fn deserialize<'de, D: Deserializer<'de>>(de: D) -> Result<OffsetDateTime, D::Error> {
+        Ok(OffsetDateTime::from_unix_timestamp(de.deserialize_i64(I64Visitor)?).unwrap_or_else(|_| OffsetDateTime::now_utc()))
+    }
+}
+
+pub(crate) struct PersistentState(HashMap<String, DownloadableFile>);
+impl PersistentState {
+    pub(crate) async fn load() -> std::io::Result<Self> {
+        let open_result = File::open(storage_dir().join(STATE_FILE_NAME)).await;
+        match open_result {
+            Ok(mut f) => {
+                let mut buf = String::new();
+                f.read_to_string(&mut buf).await?;
+                let map: HashMap<String, DownloadableFile> = serde_json::from_str(&buf)?;
+                info!("Loaded {} file entries from persistent storage", map.len());
+                let mut filtered: HashMap<String, DownloadableFile> = HashMap::new();
+                for (key, info) in map.into_iter() {
+                    if !crate::util::is_ascii_alphanumeric(&key) {
+                        error!("Invalid key in persistent storage: {}", key);
+                        continue;
+                    }
+                    let file = if let Ok(f) = File::open(storage_dir().join(&key)).await {
+                        f
+                    } else {
+                        error!("Unable to open file {} referenced in persistent storage", key);
+                        continue;
+                    };
+                    let metadata = if let Ok(md) = file.metadata().await {
+                        md
+                    } else {
+                        error!("Unable to get metadata for file {} referenced in persistent storage", key);
+                        continue;
+                    };
+                    if metadata.len() != info.size {
+                        error!("Mismatched file size for file {} referenced in persistent storage: expected {}, found {}", key, info.size, metadata.len());
+                        continue
+                    }
+                    filtered.insert(key, info);
+                }
+                Ok(Self(filtered))
+            }
+            Err(e) => {
+                if let ErrorKind::NotFound = e.kind() {
+                    Ok(Self(HashMap::new()))
+                } else {
+                    Err(e)
+                }
+            }
+        }
+    }
+
+    async fn save(&mut self) -> std::io::Result<()> {
+        File::create(storage_dir().join(STATE_FILE_NAME)).await?.write_all(&serde_json::to_vec_pretty(&self.0)?).await
+    }
+
+    pub(crate) async fn add_file(&mut self, key: String, file: DownloadableFile) -> std::io::Result<()> {
+        self.0.insert(key, file);
+        self.save().await
+    }
+
+    pub(crate) fn lookup_file(&self, key: &str) -> Option<DownloadableFile> {
+        self.0.get(key).map(|f| f.clone())
+    }
+
+    pub(crate) async fn remove_file(&mut self, key: &str) -> std::io::Result<()> {
+        self.0.remove(key);
+        self.save().await
+    }
+
+    pub(crate) fn remove_uploader(&mut self, key: &str) {
+        if let Some(f) = self.0.get_mut(key) {
+            f.uploader.take();
+        }
+    }
+}