refactor: make crawler importable and add export pipeline

Move monkeyd and pdfout out of internal/ so other modules can import them,
and add export.Export, which holds the crawl-to-PDF sequence the CLI used to
inline. The CLI now parses flags and delegates, so an embedding program gets
the same defaults and validation.

monkeyd-crawler/export/export_test.go

@@ -0,0 +1,187 @@
+package export
+
+import (
+	"testing"
+	"time"
+)
+
+func TestApplyDefaultsFillsUnsetFields(t *testing.T) {
+	req := Request{NovelURL: "https://monkeydd.com/example.html"}
+	req.applyDefaults()
+
+	if req.Page != DefaultPage {
+		t.Errorf("Page = %q, want %q", req.Page, DefaultPage)
+	}
+	if req.FontSize != DefaultFontSize {
+		t.Errorf("FontSize = %v, want %v", req.FontSize, DefaultFontSize)
+	}
+	if req.LineSpacing != DefaultLineSpacing {
+		t.Errorf("LineSpacing = %v, want %v", req.LineSpacing, DefaultLineSpacing)
+	}
+	if req.Margin != DefaultMargin {
+		t.Errorf("Margin = %v, want %v", req.Margin, DefaultMargin)
+	}
+	if req.Workers != DefaultWorkers {
+		t.Errorf("Workers = %v, want %v", req.Workers, DefaultWorkers)
+	}
+	if req.Delay != DefaultDelay {
+		t.Errorf("Delay = %v, want %v", req.Delay, DefaultDelay)
+	}
+	if req.Retries != DefaultRetries {
+		t.Errorf("Retries = %v, want %v", req.Retries, DefaultRetries)
+	}
+	if req.CacheDir != DefaultCacheDir {
+		t.Errorf("CacheDir = %q, want %q", req.CacheDir, DefaultCacheDir)
+	}
+}
+
+func TestApplyDefaultsKeepsExplicitValues(t *testing.T) {
+	req := Request{
+		NovelURL:    "https://monkeydd.com/example.html",
+		Page:        "a5",
+		FontSize:    14,
+		LineSpacing: 1.4,
+		Margin:      10,
+		Workers:     2,
+		Delay:       time.Second,
+		Retries:     1,
+		CacheDir:    "/tmp/pages",
+	}
+	req.applyDefaults()
+
+	if req.Page != "a5" || req.FontSize != 14 || req.LineSpacing != 1.4 {
+		t.Errorf("layout fields overwritten: %+v", req)
+	}
+	if req.Margin != 10 || req.Workers != 2 || req.Delay != time.Second || req.Retries != 1 {
+		t.Errorf("fetch fields overwritten: %+v", req)
+	}
+	if req.CacheDir != "/tmp/pages" {
+		t.Errorf("CacheDir = %q, want /tmp/pages", req.CacheDir)
+	}
+}
+
+// A zero Margin is indistinguishable from "unset", so it becomes the default.
+// NoCache and NoDelay exist precisely because "none" must survive that rule.
+func TestApplyDefaultsHonoursOptOuts(t *testing.T) {
+	req := Request{NovelURL: "https://monkeydd.com/example.html", NoCache: true, NoDelay: true}
+	req.applyDefaults()
+
+	if req.CacheDir != "" {
+		t.Errorf("NoCache left CacheDir = %q, want empty", req.CacheDir)
+	}
+	if req.Delay != 0 {
+		t.Errorf("NoDelay left Delay = %v, want 0", req.Delay)
+	}
+}
+
+// Opt-outs win over an explicitly set value so a caller cannot end up with both.
+func TestApplyDefaultsOptOutsOverrideExplicitValues(t *testing.T) {
+	req := Request{
+		NovelURL: "https://monkeydd.com/example.html",
+		CacheDir: "/tmp/pages",
+		NoCache:  true,
+		Delay:    time.Second,
+		NoDelay:  true,
+	}
+	req.applyDefaults()
+
+	if req.CacheDir != "" {
+		t.Errorf("CacheDir = %q, want empty", req.CacheDir)
+	}
+	if req.Delay != 0 {
+		t.Errorf("Delay = %v, want 0", req.Delay)
+	}
+}
+
+func TestValidate(t *testing.T) {
+	tests := []struct {
+		name    string
+		req     Request
+		wantErr bool
+	}{
+		{
+			name: "defaults are valid",
+			req:  Request{NovelURL: "https://monkeydd.com/example.html"},
+		},
+		{
+			name:    "missing url",
+			req:     Request{},
+			wantErr: true,
+		},
+		{
+			name:    "non-http scheme",
+			req:     Request{NovelURL: "ftp://monkeydd.com/example.html"},
+			wantErr: true,
+		},
+		{
+			name:    "scheme-less url",
+			req:     Request{NovelURL: "monkeydd.com/example.html"},
+			wantErr: true,
+		},
+		{
+			name:    "unknown page preset",
+			req:     Request{NovelURL: "https://monkeydd.com/example.html", Page: "letter"},
+			wantErr: true,
+		},
+		{
+			name:    "negative font size",
+			req:     Request{NovelURL: "https://monkeydd.com/example.html", FontSize: -1},
+			wantErr: true,
+		},
+		{
+			name:    "negative line spacing",
+			req:     Request{NovelURL: "https://monkeydd.com/example.html", LineSpacing: -1},
+			wantErr: true,
+		},
+		{
+			name:    "negative margin",
+			req:     Request{NovelURL: "https://monkeydd.com/example.html", Margin: -1},
+			wantErr: true,
+		},
+		{
+			name:    "zero workers is filled by defaults, negative is not",
+			req:     Request{NovelURL: "https://monkeydd.com/example.html", Workers: -1},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := tt.req
+			req.applyDefaults()
+			err := req.validate()
+			if tt.wantErr && err == nil {
+				t.Error("validate() = nil, want error")
+			}
+			if !tt.wantErr && err != nil {
+				t.Errorf("validate() = %v, want nil", err)
+			}
+		})
+	}
+}
+
+func TestSafeFileName(t *testing.T) {
+	tests := []struct {
+		title    string
+		fallback string
+		want     string
+	}{
+		{"Trở Lại Năm Tháng Cũ", "slug", "Trở-Lại-Năm-Tháng-Cũ"},
+		{"Chapter: One / Two", "slug", "Chapter-One-Two"},
+		{"  ---  ", "slug", "slug"},
+		{"", "slug", "slug"},
+	}
+	for _, tt := range tests {
+		if got := SafeFileName(tt.title, tt.fallback); got != tt.want {
+			t.Errorf("SafeFileName(%q, %q) = %q, want %q", tt.title, tt.fallback, got, tt.want)
+		}
+	}
+}
+
+func TestResultSummary(t *testing.T) {
+	r := &Result{Title: "Example", Chapters: 12, Words: 3400}
+	want := "Example — 12 chapters, 3400 words"
+	if got := r.Summary(); got != want {
+		t.Errorf("Summary() = %q, want %q", got, want)
+	}
+}