Simplify RAM management

virtweb_backend/src/utils/file_size_utils.rs

@@ -1,3 +1,12 @@
+use std::ops::Mul;
+
+#[derive(thiserror::Error, Debug)]
+enum FilesSizeUtilsError {
+    #[error("UnitConvertError: {0}")]
+    UnitConvert(String),
+}
+
+/// Holds a data size, convertible in any form
 #[derive(
     serde::Serialize,
     serde::Deserialize,
@@ -25,6 +34,30 @@ impl FileSize {
         Self(gb * 1000 * 1000 * 1000)
     }
 
+    /// Convert size unit to MB
+    pub fn from_size_unit(unit: &str, value: usize) -> anyhow::Result<Self> {
+        let fact = match unit {
+            "bytes" | "b" => 1f64,
+            "KB" => 1000f64,
+            "MB" => 1000f64 * 1000f64,
+            "GB" => 1000f64 * 1000f64 * 1000f64,
+            "TB" => 1000f64 * 1000f64 * 1000f64 * 1000f64,
+
+            "k" | "KiB" => 1024f64,
+            "M" | "MiB" => 1024f64 * 1024f64,
+            "G" | "GiB" => 1024f64 * 1024f64 * 1024f64,
+            "T" | "TiB" => 1024f64 * 1024f64 * 1024f64 * 1024f64,
+
+            _ => {
+                return Err(
+                    FilesSizeUtilsError::UnitConvert(format!("Unknown size unit: {unit}")).into(),
+                );
+            }
+        };
+
+        Ok(Self((value as f64).mul(fact) as usize))
+    }
+
     /// Get file size as bytes
     pub fn as_bytes(&self) -> usize {
         self.0
@@ -35,3 +68,24 @@ impl FileSize {
         self.0 / (1000 * 1000)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::utils::file_size_utils::FileSize;
+
+    #[test]
+    fn convert_units_mb() {
+        assert_eq!(FileSize::from_size_unit("MB", 1).unwrap().as_mb(), 1);
+        assert_eq!(FileSize::from_size_unit("MB", 1000).unwrap().as_mb(), 1000);
+        assert_eq!(
+            FileSize::from_size_unit("GB", 1000).unwrap().as_mb(),
+            1000 * 1000
+        );
+        assert_eq!(FileSize::from_size_unit("GB", 1).unwrap().as_mb(), 1000);
+        assert_eq!(FileSize::from_size_unit("GiB", 3).unwrap().as_mb(), 3221);
+        assert_eq!(
+            FileSize::from_size_unit("KiB", 488281).unwrap().as_mb(),
+            499
+        );
+    }
+}