most done.

src/main.rs

@@ -1,3 +1,97 @@
-fn main() {
-    println!("Hello, world!");
+mod cli;
+mod constants;
+mod head_hash;
+mod meta;
+mod utils;
+
+use std::fs::{self, File};
+use std::io::Write;
+use std::path::{Path, PathBuf};
+use std::time::Instant;
+
+use anyhow::{Context, Result};
+use clap::Parser;
+use meta::{DirSnapshot, FileMeta};
+
+fn main() -> Result<()> {
+    let started = Instant::now();
+    let cli = cli::Cli::parse();
+    let target = cli.resolve_path()?;
+    println!("目标: {}", target.display());
+
+    if target.is_dir() {
+        process_dir(&target)?;
+    } else {
+        process_file(&target)?;
+    }
+
+    println!("耗时: {:?}", started.elapsed());
+    Ok(())
+}
+
+fn process_file(path: &Path) -> Result<()> {
+    let meta = FileMeta::from_path(path)?;
+    let meta_dir = path
+        .parent()
+        .map(Path::to_path_buf)
+        .unwrap_or_else(|| PathBuf::from("."))
+        .join("meta");
+    fs::create_dir_all(&meta_dir)
+        .with_context(|| format!("无法创建目录: {}", meta_dir.display()))?;
+
+    let save_path = meta_dir.join(format!("{}.json", meta.basename));
+    if !save_path.exists() {
+        let json = meta.to_pretty_json()?;
+        println!("{}", json);
+        fs::write(&save_path, json)?;
+        return Ok(());
+    }
+
+    let existing = File::open(&save_path)
+        .with_context(|| format!("无法读取历史元数据: {}", save_path.display()))?;
+    let old_meta = FileMeta::from_reader(existing)?;
+    if meta.matches(&old_meta) {
+        println!("校验通过.");
+    } else {
+        println!("校验失败!");
+        println!("现校验文件:");
+        println!("{}", meta.to_pretty_json()?);
+        println!("原校验文件:");
+        println!("{}", old_meta.to_pretty_json()?);
+    }
+
+    Ok(())
+}
+
+fn process_dir(path: &Path) -> Result<()> {
+    let save_path = path.join("meta.json");
+    let old_path = path.join("meta-old.json");
+    let has_old = save_path.exists();
+
+    if has_old {
+        if old_path.exists() {
+            fs::remove_file(&old_path)?;
+        }
+        fs::rename(&save_path, &old_path)
+            .with_context(|| format!("无法备份旧文件: {}", save_path.display()))?;
+    }
+
+    let snapshot = DirSnapshot::build_root(path)?;
+    let json = serde_json::to_string_pretty(&snapshot)?;
+    let mut file =
+        File::create(&save_path).with_context(|| format!("无法写入: {}", save_path.display()))?;
+    file.write_all(json.as_bytes())?;
+
+    if has_old {
+        let old_meta = FileMeta::from_path(&old_path)?;
+        let new_meta = FileMeta::from_path(&save_path)?;
+        if old_meta.matches(&new_meta) {
+            println!("校验通过.");
+            fs::remove_file(&old_path)?;
+        } else {
+            println!("校验失败!");
+        }
+    }
+
+    Ok(())
 }