feat: custom PTP implementation

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

src/camera/ptp/error.rs

@@ -0,0 +1,53 @@
+use std::{fmt, io};
+
+use crate::camera::ptp::enums::ResponseCode;
+
+#[derive(Debug)]
+pub enum Error {
+    Response(u16),
+    Malformed(String),
+    Usb(rusb::Error),
+    Io(io::Error),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Self::Response(r) => {
+                let name = ResponseCode::try_from(r)
+                    .map_or_else(|_| "Unknown".to_string(), |c| format!("{c:?}"));
+                write!(f, "{name} (0x{r:04x})")
+            }
+            Self::Usb(ref e) => write!(f, "USB error: {e}"),
+            Self::Io(ref e) => write!(f, "IO error: {e}"),
+            Self::Malformed(ref e) => write!(f, "{e}"),
+        }
+    }
+}
+
+impl ::std::error::Error for Error {
+    fn cause(&self) -> Option<&dyn (::std::error::Error)> {
+        match *self {
+            Self::Usb(ref e) => Some(e),
+            Self::Io(ref e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
+impl From<rusb::Error> for Error {
+    fn from(e: rusb::Error) -> Self {
+        Self::Usb(e)
+    }
+}
+
+impl From<io::Error> for Error {
+    fn from(e: io::Error) -> Self {
+        match e.kind() {
+            io::ErrorKind::UnexpectedEof => {
+                Self::Malformed("Unexpected end of message".to_string())
+            }
+            _ => Self::Io(e),
+        }
+    }
+}