feat: argparse and dry-run.

src/dry_run.rs

@@ -0,0 +1,48 @@
+use std::path::Path;
+
+pub struct ShellScript {
+    lines: Vec<String>,
+}
+
+impl ShellScript {
+    pub fn new() -> Self {
+        Self {
+            lines: Vec::new(),
+        }
+    }
+
+    pub fn add_comment(&mut self, comment: &str) {
+        self.lines.push(format!("# {}", comment));
+    }
+
+    pub fn add_variable(&mut self, name: &str, value: &Path) {
+        let escaped = escape_path(value);
+        self.lines.push(format!("{}=\"{}\"", name, escaped));
+    }
+
+    pub fn add_command(&mut self, command: &str) {
+        self.lines.push(command.to_string());
+    }
+
+    pub fn add_empty_line(&mut self) {
+        self.lines.push(String::new());
+    }
+
+    pub fn output(&self) -> String {
+        self.lines.join("\n")
+    }
+}
+
+fn escape_path(path: &Path) -> String {
+    path.display().to_string().replace('"', r#"\""#).replace('$', r#"\$"#)
+}
+
+pub fn print_shell_script_header() {
+    println!("#!/bin/sh");
+    println!("# Generated by bilibili-merge dry-run mode");
+    println!();
+}
+
+pub fn print_shell_script(script: &ShellScript) {
+    println!("{}", script.output());
+}