feat: argparse and dry-run.

src/main.rs

@@ -1,15 +1,52 @@
+mod audio_converter;
+mod dry_run;
+mod ffmpeg;
+mod file_finder;
 mod merge;
+mod video_merger;
 
-use std::env;
+use clap::Parser;
 use std::io::Result;
 use std::path::PathBuf;
 
-fn main() -> Result<()> {
-    let args: Vec<String> = env::args().collect();
-    let merge_path = if args.len() > 1 {
-        PathBuf::from(args[1].as_str())
-    } else {
-        PathBuf::from(".")
-    };
-    merge::merge_video_from_path(&merge_path)
+#[derive(Parser)]
+#[command(name = "bilibili-merge")]
+#[command(about = "Merge bilibili downloaded videos with audio")]
+#[command(long_about = "Merge bilibili downloaded videos with audio.
+
+This tool automatically:
+1. Finds the largest video file in the specified directory (by file size)
+2. Looks for the corresponding audio file (.m4a) with the same base name
+3. Converts the audio to AAC format
+4. Merges the video and audio into a single file
+
+The original video file will be renamed to 'original.<extension>' as a backup.
+The merged file will be saved as '<original_name>.mp4' regardless of the input format.")]
+struct Args {
+    /// Path to the directory containing video and audio files
+    ///
+    /// The tool will automatically select the largest file (by size) in this directory
+    /// as the video file to merge. Make sure only one video file exists, or the largest
+    /// one will be selected.
+    #[arg(default_value = ".")]
+    path: PathBuf,
+
+    /// Dry run mode: show what would be done without actually doing it
+    ///
+    /// In dry-run mode, the tool will output a shell script showing all operations
+    /// that would be performed. You can copy and execute this script manually if needed.
+    #[arg(short = 'n', long = "dry-run")]
+    dry_run: bool,
+
+    /// Force overwrite existing files
+    ///
+    /// By default, the tool will not overwrite existing files. Use this flag to
+    /// force overwrite if the output file already exists.
+    #[arg(short = 'f', long = "force")]
+    force: bool,
+}
+
+fn main() -> Result<()> {
+    let args = Args::parse();
+    merge::merge_video_from_path(&args.path, args.dry_run, args.force)
 }