refactor: make GenerateDiagram pure — return RenderOutput instead of writing files

crates/presentation/src/lib.rs

@@ -6,13 +6,13 @@ use archlens_application::queries::AnalyzeCodebase;
 use archlens_application::use_cases::{
     check_freshness::CheckFreshness,
     diff_diagram::DiffDiagram,
-    generate_diagram::{GenerateDiagram, write_split},
+    generate_diagram::GenerateDiagram,
 };
 use archlens_ascii::AsciiRenderer;
 use archlens_cargo_workspace::CargoWorkspaceAnalyzer;
 use archlens_d2::D2Renderer;
 use archlens_domain::{
-    BoundaryRule, DiagramLevel, NormalizedGraph,
+    BoundaryRule, DiagramLevel, NormalizedGraph, RenderOutput,
     ports::{ConfigLoader, ProjectAnalyzer},
 };
 use archlens_html::HtmlRenderer;
@@ -70,7 +70,6 @@ pub fn run(args: Cli) -> Result<()> {
         .iter()
         .filter_map(|s| BoundaryRule::parse(s))
         .collect();
-    let output_dir = args.output.as_ref().map(std::path::PathBuf::from);
 
     let use_case = GenerateDiagram {
         graph,
@@ -78,22 +77,44 @@ pub fn run(args: Cli) -> Result<()> {
         allow_rules: allow,
         deny_rules: deny,
         split_by_module: args.split_by_module,
-        format_ext: format_extension(&args.format).to_string(),
-        output_dir,
     };
 
-    let violations = use_case.check_violations_only();
-    if args.strict && !violations.is_empty() {
+    let result = use_case.execute()?;
+    if args.strict && !result.violations.is_empty() {
         bail!(
             "{} boundary rule violation(s) in strict mode",
-            violations.len()
+            result.violations.len()
         );
     }
-    use_case.execute()?;
+    for v in &result.violations {
+        eprintln!("RULE VIOLATION: {}", v.message());
+    }
+    write_diagram_output(&result.output, args.output.as_deref(), args.split_by_module)?;
 
     Ok(())
 }
 
+fn write_diagram_output(output: &RenderOutput, output_path: Option<&str>, split: bool) -> Result<()> {
+    if split {
+        let dir = std::path::PathBuf::from(output_path.unwrap_or("."));
+        std::fs::create_dir_all(&dir)?;
+        for file in output.files() {
+            std::fs::write(dir.join(file.name()), file.content())?;
+        }
+    } else if let Some(path) = output_path {
+        let p = std::path::Path::new(path);
+        if let Some(parent) = p.parent() {
+            std::fs::create_dir_all(parent)?;
+        }
+        let content = output.files().first().map(|f| f.content()).unwrap_or("");
+        std::fs::write(p, content)?;
+    } else {
+        let content = output.files().first().map(|f| f.content()).unwrap_or("");
+        print!("{content}");
+    }
+    Ok(())
+}
+
 fn load_config(args: &Cli) -> Result<TomlConfigLoader> {
     match &args.config {
         Some(path) => Ok(TomlConfigLoader::from_path(std::path::Path::new(path))?),
@@ -194,15 +215,6 @@ fn create_renderer(
     }
 }
 
-fn format_extension(format: &str) -> &str {
-    match format {
-        "mermaid" => "mmd",
-        "d2" => "d2",
-        "html" => "html",
-        _ => "txt",
-    }
-}
-
 fn run_diff(args: &Cli, existing_path: &std::path::Path) -> Result<()> {
     init_tracing(args.verbose);
 
@@ -332,25 +344,12 @@ fn run_watch(args: Cli) -> Result<()> {
     use std::time::{Duration, Instant};
 
     let level = parse_level(&args.level);
-    let ext = format_extension(&args.format);
     let debounce = Duration::from_millis(500);
 
     let run_once = |args: &Cli| -> Result<()> {
         let config_loader = load_config(args)?;
         let graph = build_graph(args, level)?;
         let renderer = create_renderer(&args.format, level, !args.no_weights)?;
-        let output_dir = args.output.as_ref().map(std::path::PathBuf::from);
-
-        if args.split_by_module {
-            write_split(&graph, &*renderer, &output_dir, ext)?;
-        } else {
-            let rendered = renderer.render(graph.as_graph())?;
-            let content = rendered.files().first().map(|f| f.content()).unwrap_or("");
-            match &output_dir {
-                Some(path) => std::fs::write(path, content)?,
-                None => print!("{content}"),
-            }
-        }
 
         let (raw_allow, raw_deny) = config_loader.load_rules();
         let allow: Vec<BoundaryRule> = raw_allow
@@ -361,19 +360,18 @@ fn run_watch(args: Cli) -> Result<()> {
             .iter()
             .filter_map(|s| BoundaryRule::parse(s))
             .collect();
-        if !allow.is_empty() || !deny.is_empty() {
-            let use_case = GenerateDiagram {
-                graph,
-                renderer,
-                allow_rules: allow,
-                deny_rules: deny,
-                split_by_module: false,
-                format_ext: ext.to_string(),
-                output_dir: None,
-            };
-            for v in use_case.check_violations_only() {
-                eprintln!("RULE VIOLATION: {v}");
-            }
+
+        let use_case = GenerateDiagram {
+            graph,
+            renderer,
+            allow_rules: allow,
+            deny_rules: deny,
+            split_by_module: args.split_by_module,
+        };
+        let result = use_case.execute()?;
+        write_diagram_output(&result.output, args.output.as_deref(), args.split_by_module)?;
+        for v in &result.violations {
+            eprintln!("RULE VIOLATION: {}", v.message());
         }
         Ok(())
     };