Huge refactor. Introduce anyhow for error handling.

src/io.rs

@@ -1,4 +1,5 @@
 use std::io::{self, Seek, SeekFrom};
+use std::path::{Path, PathBuf};
 
 /// Get length of data stream.
 /// Physical length of data stream in bytes
@@ -13,3 +14,23 @@ pub fn get_stream_length<S: Seek>(stream: &mut S) -> io::Result<u64> {
 
     len
 }
+
+/// Generates a file path if one not provided.
+/// source_name for fallback name.
+pub fn get_path<P>(file_path: &Option<P>, source_name: &P, extension: &str) -> Option<PathBuf>
+where
+    P: AsRef<Path>,
+{
+    if let Some(f) = file_path {
+        return f.as_ref().to_path_buf().into();
+    }
+
+    PathBuf::from(format!(
+        "{:?}.{}",
+        source_name.as_ref().to_str()?,
+        extension
+    ))
+    .as_path()
+    .to_owned()
+    .into()
+}