display file targeted and improve error handling

src/finder_errors.rs

@@ -8,6 +8,8 @@ pub enum FinderError {
     StdIoError { e: std::io::Error },
     #[error("Invalid zip file error - {message}")]
     InvalidZip { message: String },
+    #[error("File number not found within archive error - '{file_number}'")]
+    FileNotFoundInArchive { file_number: usize },
     #[error("CLI argument error - {message:?}")]
     CliArgumentError { message: String },
     #[error("CLI argument error ({e})")]
@@ -20,6 +22,10 @@ impl FinderError {
     pub fn invalid_zip_error(message: String) -> Self {
         InvalidZip { message }
     }
+
+    pub fn file_not_found_error(file_number: usize) -> Self {
+        FinderError::FileNotFoundInArchive { file_number }
+    }
 }
 
 impl From<std::io::Error> for FinderError {

src/password_finder.rs

@@ -39,7 +39,17 @@ pub fn password_finder(
     progress_bar.set_draw_target(draw_target);
 
     // Fail early if the zip file is not valid
-    let aes_info = validate_zip(file_path, file_number)?;
+    let validated_zip = validate_zip(file_path, file_number)?;
+    match &validated_zip.file_name {
+        Some(file_name) => {
+            progress_bar.println(format!("Targeting file '{file_name}' within the archive"))
+        }
+        None => progress_bar.println(format!(
+            "Cannot get file name from archive for --fileNumber {file_number}"
+        )),
+    }
+
+    let aes_info = validated_zip.aes_info;
     match &aes_info {
         Some(aes_info) => progress_bar.println(format!(
             "Archive encrypted with AES{} - expect a long wait time",

src/zip_utils.rs

@@ -1,6 +1,7 @@
 use crate::finder_errors::FinderError;
 use std::fs::File;
 use std::path::Path;
+use zip::result::ZipError;
 use zip::result::ZipError::UnsupportedArchive;
 
 #[derive(Clone, Debug)]
@@ -25,11 +26,26 @@ impl AesInfo {
     }
 }
 
+pub struct ValidatedZip {
+    pub aes_info: Option<AesInfo>,
+    pub file_name: Option<String>,
+}
+
+impl ValidatedZip {
+    pub fn new(aes_info: Option<AesInfo>, file_name: Option<String>) -> Self {
+        ValidatedZip {
+            aes_info,
+            file_name,
+        }
+    }
+}
+
 // validate that the zip requires a password
-pub fn validate_zip(file_path: &Path, file_number: usize) -> Result<Option<AesInfo>, FinderError> {
+pub fn validate_zip(file_path: &Path, file_number: usize) -> Result<ValidatedZip, FinderError> {
     let file = File::open(file_path)?;
     let mut archive = zip::ZipArchive::new(file)?;
     let aes_data = archive.get_aes_verification_key_and_salt(file_number);
+    let file_name = archive.name_for_index(file_number).map(|s| s.to_string());
     let zip_result = archive.by_index(file_number);
     match zip_result {
         Ok(z) => Err(FinderError::invalid_zip_error(format!(
@@ -38,17 +54,20 @@ pub fn validate_zip(file_path: &Path, file_number: usize) -> Result<Option<AesIn
             z.name()
         ))),
         Err(UnsupportedArchive("Password required to decrypt file")) => {
-            if let Some(aes_zip_info) = aes_data.expect("Archive validated before-hand") {
-                let aes_key_length = aes_zip_info.aes_mode.key_length();
-                let verification_value = aes_zip_info.verification_value;
-                let salt = aes_zip_info.salt;
-                Ok(Some(AesInfo::new(aes_key_length, verification_value, salt)))
-            } else {
-                Ok(None)
-            }
+            let aes_info =
+                if let Some(aes_zip_info) = aes_data.expect("Archive validated before-hand") {
+                    let aes_key_length = aes_zip_info.aes_mode.key_length();
+                    let verification_value = aes_zip_info.verification_value;
+                    let salt = aes_zip_info.salt;
+                    Some(AesInfo::new(aes_key_length, verification_value, salt))
+                } else {
+                    None
+                };
+            Ok(ValidatedZip::new(aes_info, file_name))
         }
-        Err(e) => Err(FinderError::invalid_zip_error(format!(
-            "unexpected error while opening archive: {e:?}"
+        Err(ZipError::FileNotFound) => Err(FinderError::file_not_found_error(file_number)),
+        Err(other) => Err(FinderError::invalid_zip_error(format!(
+            "unexpected error while opening archive: {other:?}"
         ))),
     }
 }