Add function to report devices activity

central_backend/src/logs/log_entry.rs

@@ -0,0 +1,17 @@
+use crate::devices::device::DeviceId;
+use crate::logs::severity::LogSeverity;
+
+#[derive(serde::Serialize, serde::Deserialize, Debug, Clone)]
+pub struct LogEntry {
+    /// If no device is specified then the message comes from the backend
+    pub device_id: Option<DeviceId>,
+    pub time: u64,
+    pub severity: LogSeverity,
+    pub message: String,
+}
+
+impl LogEntry {
+    pub fn serialize(&self) -> anyhow::Result<String> {
+        Ok(serde_json::to_string(self)?)
+    }
+}

central_backend/src/logs/logs_manager.rs

@@ -0,0 +1,41 @@
+use crate::app_config::AppConfig;
+use crate::devices::device::DeviceId;
+use crate::logs::log_entry::LogEntry;
+use crate::logs::severity::LogSeverity;
+use crate::utils::time_utils::{curr_day_number, time_secs};
+use fs4::fs_std::FileExt;
+use std::fs::OpenOptions;
+use std::io::{Seek, SeekFrom, Write};
+
+pub fn save_log(
+    device: Option<&DeviceId>,
+    severity: LogSeverity,
+    message: String,
+) -> anyhow::Result<()> {
+    let log_path = AppConfig::get().log_of_day(curr_day_number());
+
+    let mut file = OpenOptions::new()
+        .append(true)
+        .create(true)
+        .open(&log_path)?;
+
+    file.lock_exclusive()?;
+    file.seek(SeekFrom::End(0))?;
+    file.write_all(
+        format!(
+            "{}\n",
+            (LogEntry {
+                device_id: device.cloned(),
+                time: time_secs(),
+                severity,
+                message,
+            })
+            .serialize()?
+        )
+        .as_bytes(),
+    )?;
+    file.flush()?;
+    file.unlock()?;
+
+    Ok(())
+}

central_backend/src/logs/mod.rs

@@ -0,0 +1,3 @@
+pub mod log_entry;
+pub mod logs_manager;
+pub mod severity;

central_backend/src/logs/severity.rs

@@ -0,0 +1,7 @@
+#[derive(serde::Serialize, serde::Deserialize, Copy, Clone, Debug)]
+pub enum LogSeverity {
+    Debug,
+    Info,
+    Warn,
+    Error,
+}