feat(cph): add outline export command

crates/cph-cli/src/main.rs

@@ -7,11 +7,14 @@
 //! exits 1 when there is any `Error`-severity diagnostic (warnings alone exit
 //! 0); `build` exits 1 when the PDF could not be produced.
 
+use std::fs::OpenOptions;
+use std::io::Write;
 use std::path::PathBuf;
 use std::process::ExitCode;
 
 use clap::{Parser, Subcommand};
 use cph_check::CheckReport;
+use cph_model::OutlineDocument;
 use cph_typst::Engine;
 
 /// The `cph` checker for curriculum engineering files.
@@ -70,6 +73,21 @@ enum Command {
         #[arg(short = 'o', long, value_name = "OUT")]
         out: Option<PathBuf>,
     },
+    /// Export the teacher-facing outline as Markdown, PDF, or JSON.
+    Outline {
+        /// Path to the engineering-file root. Defaults to the current directory.
+        #[arg(default_value = ".")]
+        path: PathBuf,
+        /// Output format. Defaults to PDF.
+        #[arg(long, value_enum, default_value_t = OutlineFormat::Pdf)]
+        format: OutlineFormat,
+        /// Output path. Defaults to `<PATH>/outline.<format>`.
+        #[arg(short = 'o', long, value_name = "OUT")]
+        out: Option<PathBuf>,
+        /// Allow replacing an existing output file.
+        #[arg(long)]
+        force: bool,
+    },
     /// Print a shell-completion script to stdout (clap_complete; ADR-0013 opt-in
     /// sibling: a local convenience, no lesson involved). Pipe to your shell's
     /// completion file, e.g. `cph completions zsh > ~/.zfunc/_cph`.
@@ -79,6 +97,23 @@ enum Command {
     },
 }
 
+#[derive(Debug, Clone, Copy, clap::ValueEnum)]
+enum OutlineFormat {
+    Md,
+    Pdf,
+    Json,
+}
+
+impl OutlineFormat {
+    fn extension(self) -> &'static str {
+        match self {
+            Self::Md => "md",
+            Self::Pdf => "pdf",
+            Self::Json => "json",
+        }
+    }
+}
+
 #[derive(Debug, Clone, Copy, clap::ValueEnum)]
 enum CompletionTarget {
     Bash,
@@ -100,6 +135,12 @@ fn main() -> ExitCode {
         Command::Check { path } => run_check(&path, &engine),
         Command::Build { path, targets, out } => run_build_command(&path, &engine, targets, out),
         Command::Bundle { path, targets, out } => run_bundle_command(&path, &engine, targets, out),
+        Command::Outline {
+            path,
+            format,
+            out,
+            force,
+        } => run_outline(&path, &engine, format, out, force),
         Command::Completions { shell } => run_completions(shell),
     }
 }
@@ -157,6 +198,135 @@ fn run_check(path: &std::path::Path, engine: &Engine) -> ExitCode {
     }
 }
 
+fn run_outline(
+    path: &std::path::Path,
+    engine: &Engine,
+    format: OutlineFormat,
+    out: Option<PathBuf>,
+    force: bool,
+) -> ExitCode {
+    let out_path = out.unwrap_or_else(|| path.join(format!("outline.{}", format.extension())));
+
+    if out_path.exists() && !force {
+        eprintln!(
+            "warning: output '{}' already exists; pass --force to overwrite",
+            out_path.display()
+        );
+        return ExitCode::FAILURE;
+    }
+
+    let (outline, report) = cph_check::outline(path);
+    print_diagnostics(&report);
+    let Some(outline) = outline else {
+        eprintln!("outline failed: fix the lesson before exporting");
+        return ExitCode::FAILURE;
+    };
+
+    let bytes = match format {
+        OutlineFormat::Md => render_outline_markdown(&outline).into_bytes(),
+        OutlineFormat::Json => match serde_json::to_vec_pretty(&outline) {
+            Ok(mut bytes) => {
+                bytes.push(b'\n');
+                bytes
+            }
+            Err(e) => {
+                eprintln!("outline failed: cannot serialize JSON: {e}");
+                return ExitCode::FAILURE;
+            }
+        },
+        OutlineFormat::Pdf => match engine.build_outline_pdf(&outline) {
+            Ok(bytes) => bytes,
+            Err(diags) => {
+                for diagnostic in &diags {
+                    eprintln!("{diagnostic}");
+                }
+                eprintln!("outline failed: PDF compilation failed");
+                return ExitCode::FAILURE;
+            }
+        },
+    };
+
+    if force && out_path.exists() {
+        eprintln!(
+            "warning: overwriting existing output '{}'",
+            out_path.display()
+        );
+    }
+    if let Err(e) = write_outline_output(&out_path, &bytes, force) {
+        eprintln!("outline failed: {e}");
+        return ExitCode::FAILURE;
+    }
+    println!("wrote {} ({} bytes)", out_path.display(), bytes.len());
+    ExitCode::SUCCESS
+}
+
+fn render_outline_markdown(outline: &OutlineDocument) -> String {
+    let mut body = format!("# {}\n\n", outline.title.trim());
+    if !outline.authors.is_empty() {
+        body.push_str("作者：");
+        body.push_str(&outline.authors.join("、"));
+        body.push_str("\n\n");
+    }
+    for child in &outline.children {
+        append_outline_markdown(&mut body, child, 2);
+    }
+    body
+}
+
+fn append_outline_markdown(body: &mut String, node: &cph_model::OutlineNode, level: usize) {
+    let level = level.min(6);
+    body.push_str(&"#".repeat(level));
+    body.push(' ');
+    body.push_str(&node.title);
+    if !node.kind.is_empty() {
+        body.push_str(" `[");
+        body.push_str(&node.kind);
+        body.push_str("]`");
+    }
+    body.push_str("\n\n");
+
+    if let Some(notes) = node.notes.as_deref() {
+        body.push_str("> 教学提示：\n");
+        for line in notes.lines() {
+            body.push_str("> ");
+            body.push_str(line);
+            body.push('\n');
+        }
+        body.push('\n');
+    }
+
+    for child in &node.children {
+        append_outline_markdown(body, child, level + 1);
+    }
+}
+
+fn write_outline_output(path: &std::path::Path, bytes: &[u8], force: bool) -> Result<(), String> {
+    if let Some(parent) = path
+        .parent()
+        .filter(|parent| !parent.as_os_str().is_empty())
+    {
+        std::fs::create_dir_all(parent)
+            .map_err(|e| format!("cannot create output directory '{}': {e}", parent.display()))?;
+    }
+
+    if force {
+        std::fs::write(path, bytes).map_err(|e| format!("cannot write '{}': {e}", path.display()))
+    } else {
+        let mut file = match OpenOptions::new().write(true).create_new(true).open(path) {
+            Ok(file) => file,
+            Err(e) if e.kind() == std::io::ErrorKind::AlreadyExists => {
+                return Err(format!(
+                    "output '{}' already exists; pass --force to overwrite",
+                    path.display()
+                ));
+            }
+            Err(e) => return Err(format!("cannot create '{}': {e}", path.display())),
+        };
+        file.write_all(bytes)
+            .map_err(|e| format!("cannot write '{}': {e}", path.display()))
+    }
+}
+
 /// Dispatch `cph build` (ADR-0030): with an explicit `--target` (repeatable),
 /// build exactly that ordered set; with none, batch every target the lesson
 /// declares. Each target builds **independently** — one failing does not stop