Import in separate crate and change source ID calculation

import/src/folder.rs

@@ -0,0 +1,64 @@
+use crate::error::{Error, Result};
+use crate::session::{ImportSession, ImportTrack};
+use gstreamer::ClockTime;
+use gstreamer_pbutils::Discoverer;
+use log::{warn, info};
+use sha2::{Sha256, Digest};
+use std::path::PathBuf;
+
+/// Create a new import session for the specified folder.
+pub(super) fn new(path: PathBuf) -> Result<ImportSession> {
+    let mut tracks = Vec::new();
+    let mut number: u32 = 1;
+    let mut hasher = Sha256::new();
+    let discoverer = Discoverer::new(ClockTime::from_seconds(1))?;
+
+    for entry in std::fs::read_dir(path)? {
+        let entry = entry?;
+
+        if entry.file_type()?.is_file() {
+            let path = entry.path();
+
+            let uri = glib::filename_to_uri(&path, None)
+                .or(Err(Error::u(format!("Failed to create URI from path: {:?}", path))))?;
+
+            let info = discoverer.discover_uri(&uri)?;
+
+            if !info.get_audio_streams().is_empty() {
+                let duration = info.get_duration().mseconds()
+                    .ok_or(Error::u(format!("Failed to get duration for {}.", uri)))?;
+
+                let file_name = entry.file_name();
+                let name = file_name.into_string()
+                    .or(Err(Error::u(format!(
+                        "Failed to convert OsString to String: {:?}", entry.file_name()))))?;
+
+                hasher.update(duration.to_le_bytes());
+
+                let track = ImportTrack {
+                    number,
+                    name,
+                    path,
+                    duration,
+                };
+
+                tracks.push(track);
+                number += 1;
+            } else {
+                warn!("File {} skipped, because it doesn't contain any audio streams.", uri);
+            }
+        }
+    }
+
+    let source_id = base64::encode_config(hasher.finalize(), base64::URL_SAFE);
+
+    info!("Source ID: {}", source_id);
+
+    let session = ImportSession {
+        source_id,
+        tracks,
+        copy: None,
+    };
+
+    Ok(session)
+}