package html

import (
	"errors"
	"strings"
	"testing"
)

func TestLayout_HLCRF(t *testing.T) {
	ctx := NewContext()
	layout := NewLayout("HLCRF").
		H(Raw("header")).L(Raw("left")).C(Raw("main")).R(Raw("right")).F(Raw("footer"))
	got := layout.Render(ctx)

	// Must contain semantic elements
	for _, want := range []string{"<header", "<aside", "<main", "<footer"} {
		if !strings.Contains(got, want) {
			t.Errorf("HLCRF layout missing %q in:\n%s", want, got)
		}
	}

	// Must contain ARIA roles
	for _, want := range []string{`role="banner"`, `role="complementary"`, `role="main"`, `role="contentinfo"`} {
		if !strings.Contains(got, want) {
			t.Errorf("HLCRF layout missing role %q in:\n%s", want, got)
		}
	}

	// Must contain data-block IDs
	for _, want := range []string{`data-block="H-0"`, `data-block="L-0"`, `data-block="C-0"`, `data-block="R-0"`, `data-block="F-0"`} {
		if !strings.Contains(got, want) {
			t.Errorf("HLCRF layout missing %q in:\n%s", want, got)
		}
	}

	// Must contain content
	for _, want := range []string{"header", "left", "main", "right", "footer"} {
		if !strings.Contains(got, want) {
			t.Errorf("HLCRF layout missing content %q in:\n%s", want, got)
		}
	}
}

func TestLayout_HCF(t *testing.T) {
	ctx := NewContext()
	layout := NewLayout("HCF").
		H(Raw("header")).L(Raw("left")).C(Raw("main")).R(Raw("right")).F(Raw("footer"))
	got := layout.Render(ctx)

	// HCF should have header, main, footer
	for _, want := range []string{`data-block="H-0"`, `data-block="C-0"`, `data-block="F-0"`} {
		if !strings.Contains(got, want) {
			t.Errorf("HCF layout missing %q in:\n%s", want, got)
		}
	}

	// HCF must NOT have L or R slots
	for _, unwanted := range []string{`data-block="L-0"`, `data-block="R-0"`} {
		if strings.Contains(got, unwanted) {
			t.Errorf("HCF layout should NOT contain %q in:\n%s", unwanted, got)
		}
	}
}

func TestLayout_ContentOnly(t *testing.T) {
	ctx := NewContext()
	layout := NewLayout("C").
		H(Raw("header")).L(Raw("left")).C(Raw("main")).R(Raw("right")).F(Raw("footer"))
	got := layout.Render(ctx)

	// Only C slot should render
	if !strings.Contains(got, `data-block="C-0"`) {
		t.Errorf("C layout missing data-block=\"C-0\" in:\n%s", got)
	}
	if !strings.Contains(got, "<main") {
		t.Errorf("C layout missing <main in:\n%s", got)
	}

	// No other slots
	for _, unwanted := range []string{`data-block="H-0"`, `data-block="L-0"`, `data-block="R-0"`, `data-block="F-0"`} {
		if strings.Contains(got, unwanted) {
			t.Errorf("C layout should NOT contain %q in:\n%s", unwanted, got)
		}
	}
}

func TestLayout_FluentAPI(t *testing.T) {
	layout := NewLayout("HLCRF")

	// Fluent methods should return the same layout for chaining
	result := layout.H(Raw("h")).L(Raw("l")).C(Raw("c")).R(Raw("r")).F(Raw("f"))
	if result != layout {
		t.Error("fluent methods must return the same *Layout for chaining")
	}

	got := layout.Render(NewContext())
	if got == "" {
		t.Error("fluent chain should produce non-empty output")
	}
}

func TestLayout_IgnoresInvalidSlots(t *testing.T) {
	ctx := NewContext()
	// "C" variant: populating L and R should have no effect
	layout := NewLayout("C").L(Raw("left")).C(Raw("main")).R(Raw("right"))
	got := layout.Render(ctx)

	if !strings.Contains(got, "main") {
		t.Errorf("C variant should render main content, got:\n%s", got)
	}
	if strings.Contains(got, "left") {
		t.Errorf("C variant should ignore L slot content, got:\n%s", got)
	}
	if strings.Contains(got, "right") {
		t.Errorf("C variant should ignore R slot content, got:\n%s", got)
	}
}

func TestLayout_RendersEmptySlots(t *testing.T) {
	ctx := NewContext()
	layout := NewLayout("HCF")

	got := layout.Render(ctx)

	for _, want := range []string{`<header role="banner" data-block="H-0"></header>`, `<main role="main" data-block="C-0"></main>`, `<footer role="contentinfo" data-block="F-0"></footer>`} {
		if !strings.Contains(got, want) {
			t.Errorf("empty slot should still render %q in:\n%s", want, got)
		}
	}
}

func TestValidateLayoutVariant(t *testing.T) {
	tests := []struct {
		name    string
		variant string
		wantErr bool
	}{
		{name: "valid", variant: "HCF", wantErr: false},
		{name: "invalid", variant: "HXC", wantErr: true},
		{name: "empty", variant: "", wantErr: false},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			err := ValidateLayoutVariant(tt.variant)
			if tt.wantErr {
				if err == nil {
					t.Fatalf("ValidateLayoutVariant(%q) = nil, want error", tt.variant)
				}
				if !errors.Is(err, ErrInvalidLayoutVariant) {
					t.Fatalf("ValidateLayoutVariant(%q) = %v, want ErrInvalidLayoutVariant", tt.variant, err)
				}
				return
			}

			if err != nil {
				t.Fatalf("ValidateLayoutVariant(%q) = %v, want nil", tt.variant, err)
			}
		})
	}
}

func TestLayout_VariantError(t *testing.T) {
	tests := []struct {
		name          string
		variant       string
		wantErr       bool
		wantErrString string
		wantRender    string
	}{
		{
			name:    "valid variant",
			variant: "HCF",
			wantRender: `<header role="banner" data-block="H-0">header</header>` +
				`<main role="main" data-block="C-0">main</main>` +
				`<footer role="contentinfo" data-block="F-0">footer</footer>`,
		},
		{
			name:          "mixed invalid variant",
			variant:       "HXC",
			wantErr:       true,
			wantErrString: "html: invalid layout variant HXC (invalid slot: 'X' at position 2)",
			wantRender: `<header role="banner" data-block="H-0">header</header>` +
				`<main role="main" data-block="C-0">main</main>`,
		},
		{
			name:          "multiple invalid slots",
			variant:       "H1X?",
			wantErr:       true,
			wantErrString: "html: invalid layout variant H1X? (invalid slots: '1' at position 2, 'X' at position 3, '?' at position 4)",
			wantRender:    `<header role="banner" data-block="H-0">header</header>`,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			layout := NewLayout(tt.variant)
			layout.H(Raw("header")).C(Raw("main")).F(Raw("footer"))

			if tt.wantErr {
				if layout.VariantError() == nil {
					t.Fatalf("VariantError() = nil, want sentinel error for %q", tt.variant)
				}
				if !errors.Is(layout.VariantError(), ErrInvalidLayoutVariant) {
					t.Fatalf("VariantError() = %v, want errors.Is(..., ErrInvalidLayoutVariant)", layout.VariantError())
				}
				if got := layout.VariantError().Error(); got != tt.wantErrString {
					t.Fatalf("VariantError().Error() = %q, want %q", got, tt.wantErrString)
				}
				if err, ok := layout.VariantError().(*LayoutVariantError); ok {
					switch tt.variant {
					case "HXC":
						if got := string(err.InvalidSlots()); got != "X" {
							t.Fatalf("InvalidSlots() = %q, want %q", got, "X")
						}
						if got := err.InvalidPositions(); len(got) != 1 || got[0] != 2 {
							t.Fatalf("InvalidPositions() = %v, want %v", got, []int{2})
						}
					case "H1X?":
						if got := string(err.InvalidSlots()); got != "1X?" {
							t.Fatalf("InvalidSlots() = %q, want %q", got, "1X?")
						}
						if got := err.InvalidPositions(); len(got) != 3 || got[0] != 2 || got[1] != 3 || got[2] != 4 {
							t.Fatalf("InvalidPositions() = %v, want %v", got, []int{2, 3, 4})
						}
					}
				} else {
					t.Fatalf("VariantError() has unexpected concrete type %T", layout.VariantError())
				}
			} else if layout.VariantError() != nil {
				t.Fatalf("VariantError() = %v, want nil", layout.VariantError())
			}
			if got := layout.VariantValid(); got != !tt.wantErr {
				t.Fatalf("VariantValid() = %v, want %v", got, !tt.wantErr)
			}

			got := layout.Render(NewContext())
			if got != tt.wantRender {
				t.Fatalf("Render() = %q, want %q", got, tt.wantRender)
			}
		})
	}
}

func TestLayout_RenderNilReceiver(t *testing.T) {
	var layout *Layout
	got := layout.Render(NewContext())
	if got != "" {
		t.Fatalf("nil Layout should render empty string, got %q", got)
	}
}

func TestLayout_BuilderNilReceiver(t *testing.T) {
	var layout *Layout

	if got := layout.H(Raw("header")); got != nil {
		t.Fatalf("nil Layout.H() should return nil, got %v", got)
	}
	if got := layout.L(Raw("left")); got != nil {
		t.Fatalf("nil Layout.L() should return nil, got %v", got)
	}
	if got := layout.C(Raw("main")); got != nil {
		t.Fatalf("nil Layout.C() should return nil, got %v", got)
	}
	if got := layout.R(Raw("right")); got != nil {
		t.Fatalf("nil Layout.R() should return nil, got %v", got)
	}
	if got := layout.F(Raw("footer")); got != nil {
		t.Fatalf("nil Layout.F() should return nil, got %v", got)
	}
}

func TestLayout_RenderNilContext(t *testing.T) {
	layout := NewLayout("C").C(Raw("content"))
	got := layout.Render(nil)

	if !strings.Contains(got, `data-block="C-0"`) {
		t.Fatalf("Layout.Render(nil) should still render the block ID, got:\n%s", got)
	}
	if !strings.Contains(got, "content") {
		t.Fatalf("Layout.Render(nil) should still render content, got:\n%s", got)
	}
}