package core

import "testing"

// TestCommandOutputHeight tests the Height() method for various configurations
func TestCommandOutputHeight(t *testing.T) {
	t.Run("inline mode returns 1", func(t *testing.T) {
		co := &CommandOutput{
			Title:  "Test Title",
			Lines:  []string{"line1", "line2", "line3"},
			Inline: true,
		}

		if got := co.Height(); got != 1 {
			t.Errorf("Height() = %d, want 1 for inline mode", got)
		}
	})

	t.Run("empty output with no title", func(t *testing.T) {
		co := &CommandOutput{
			Lines:  []string{},
			Inline: false,
		}

		// 0 lines + 0 title + 2 padding = 2
		want := 2
		if got := co.Height(); got != want {
			t.Errorf("Height() = %d, want %d", got, want)
		}
	})

	t.Run("one line with title", func(t *testing.T) {
		co := &CommandOutput{
			Title:  "Test",
			Lines:  []string{"line1"},
			Inline: false,
		}

		// 1 line + 1 title + 2 padding = 4
		want := 4
		if got := co.Height(); got != want {
			t.Errorf("Height() = %d, want %d", got, want)
		}
	})

	t.Run("one line without title", func(t *testing.T) {
		co := &CommandOutput{
			Lines:  []string{"line1"},
			Inline: false,
		}

		// 1 line + 0 title + 2 padding = 3
		want := 3
		if got := co.Height(); got != want {
			t.Errorf("Height() = %d, want %d", got, want)
		}
	})

	t.Run("multiple lines with title", func(t *testing.T) {
		co := &CommandOutput{
			Title:  "Output",
			Lines:  []string{"line1", "line2", "line3", "line4", "line5"},
			Inline: false,
		}

		// 5 lines + 1 title + 2 padding = 8
		want := 8
		if got := co.Height(); got != want {
			t.Errorf("Height() = %d, want %d", got, want)
		}
	})

	t.Run("whitespace-only title counts as no title", func(t *testing.T) {
		co := &CommandOutput{
			Title:  "   ",
			Lines:  []string{"line1"},
			Inline: false,
		}

		// 1 line + 0 title (whitespace) + 2 padding = 3
		want := 3
		if got := co.Height(); got != want {
			t.Errorf("Height() = %d, want %d", got, want)
		}
	})

	t.Run("empty string title counts as no title", func(t *testing.T) {
		co := &CommandOutput{
			Title:  "",
			Lines:  []string{"line1", "line2"},
			Inline: false,
		}

		// 2 lines + 0 title + 2 padding = 4
		want := 4
		if got := co.Height(); got != want {
			t.Errorf("Height() = %d, want %d", got, want)
		}
	})
}

// TestCommandOutputIsActive tests the IsActive() method
func TestCommandOutputIsActive(t *testing.T) {
	t.Run("active with lines", func(t *testing.T) {
		co := &CommandOutput{
			Lines: []string{"line1"},
		}

		if !co.IsActive() {
			t.Error("IsActive() = false, want true when lines present")
		}
	})

	t.Run("inactive with no lines", func(t *testing.T) {
		co := &CommandOutput{
			Lines: []string{},
		}

		if co.IsActive() {
			t.Error("IsActive() = true, want false when no lines")
		}
	})

	t.Run("inactive with nil lines", func(t *testing.T) {
		co := &CommandOutput{
			Lines: nil,
		}

		if co.IsActive() {
			t.Error("IsActive() = true, want false when lines is nil")
		}
	})

	t.Run("active with multiple lines", func(t *testing.T) {
		co := &CommandOutput{
			Lines: []string{"line1", "line2", "line3"},
		}

		if !co.IsActive() {
			t.Error("IsActive() = false, want true when multiple lines present")
		}
	})
}

// TestMaxOutputWindowHeight tests the maxOutputWindowHeight helper function
func TestMaxOutputWindowHeight(t *testing.T) {
	tests := []struct {
		name       string
		termHeight int
		want       int
	}{
		{"100 height terminal", 100, 75},
		{"80 height terminal", 80, 60},
		{"40 height terminal", 40, 30},
		{"24 height terminal", 24, 18},
		{"20 height terminal", 20, 15},
		{"10 height terminal", 10, 7},
		{"1 height terminal", 1, 0},
		{"0 height terminal", 0, 0},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := maxOutputWindowHeight(tt.termHeight)
			if got != tt.want {
				t.Errorf("maxOutputWindowHeight(%d) = %d, want %d", tt.termHeight, got, tt.want)
			}
		})
	}
}

// TestCommandOutputViewport tests the Viewport() method
func TestCommandOutputViewport(t *testing.T) {
	t.Run("viewport at start with small content", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"line1", "line2", "line3"},
			ScrollOffset: 0,
		}

		// Terminal height 100 → max window = 75, viewport shows all 3 lines
		viewport := co.Viewport(100)

		if len(viewport) != 3 {
			t.Errorf("Viewport() returned %d lines, want 3", len(viewport))
		}

		want := []string{"line1", "line2", "line3"}
		for i, line := range viewport {
			if line != want[i] {
				t.Errorf("Viewport()[%d] = %q, want %q", i, line, want[i])
			}
		}
	})

	t.Run("viewport at start with large content", func(t *testing.T) {
		lines := make([]string, 100)
		for i := range lines {
			lines[i] = string(rune('A' + (i % 26)))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 0,
		}

		// Terminal height 100 → max window = 75
		viewport := co.Viewport(100)

		if len(viewport) != 75 {
			t.Errorf("Viewport() returned %d lines, want 75", len(viewport))
		}

		// Should start with first line
		if viewport[0] != "A" {
			t.Errorf("Viewport()[0] = %q, want 'A'", viewport[0])
		}
	})

	t.Run("viewport scrolled down", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"A", "B", "C", "D", "E", "F", "G", "H", "I", "J"},
			ScrollOffset: 3,
		}

		// Terminal height 20 → max window = 15
		viewport := co.Viewport(20)

		// Should start at offset 3 (line "D")
		if viewport[0] != "D" {
			t.Errorf("Viewport()[0] = %q, want 'D' (offset 3)", viewport[0])
		}
	})

	t.Run("viewport with different terminal heights", func(t *testing.T) {
		lines := make([]string, 100)
		for i := range lines {
			lines[i] = string(rune('0' + (i % 10)))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 0,
		}

		// Small terminal (40 lines) → max window = 30
		viewport := co.Viewport(40)
		if len(viewport) != 30 {
			t.Errorf("Viewport(40) returned %d lines, want 30", len(viewport))
		}

		// Large terminal (200 lines) → max window = 150, but only 100 lines available
		viewport = co.Viewport(200)
		if len(viewport) != 100 {
			t.Errorf("Viewport(200) returned %d lines, want 100 (all available)", len(viewport))
		}
	})

	t.Run("viewport at maximum scroll", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"A", "B", "C", "D", "E"},
			ScrollOffset: 2, // Showing lines from index 2 onwards
		}

		// Terminal height 20 → max window = 15 (but only 3 lines available from offset 2)
		viewport := co.Viewport(20)

		want := []string{"C", "D", "E"}
		if len(viewport) != len(want) {
			t.Errorf("Viewport() returned %d lines, want %d", len(viewport), len(want))
		}

		for i, line := range viewport {
			if line != want[i] {
				t.Errorf("Viewport()[%d] = %q, want %q", i, line, want[i])
			}
		}
	})
}

// TestCommandOutputScrollDown tests the ScrollDown() method
func TestCommandOutputScrollDown(t *testing.T) {
	t.Run("scroll down with space available", func(t *testing.T) {
		lines := make([]string, 100)
		for i := range lines {
			lines[i] = string(rune('A' + (i % 26)))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 0,
		}

		// Terminal height 100 → max window = 75
		// Can scroll since 100 lines > 75 viewport
		co.ScrollDown(100)

		if co.ScrollOffset != 1 {
			t.Errorf("ScrollOffset = %d after ScrollDown, want 1", co.ScrollOffset)
		}
	})

	t.Run("scroll down multiple times", func(t *testing.T) {
		lines := make([]string, 100)
		for i := range lines {
			lines[i] = string(rune('A' + (i % 26)))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 0,
		}

		// Scroll down 5 times
		for i := 0; i < 5; i++ {
			co.ScrollDown(100)
		}

		if co.ScrollOffset != 5 {
			t.Errorf("ScrollOffset = %d after 5 ScrollDown calls, want 5", co.ScrollOffset)
		}
	})

	t.Run("cannot scroll past end of content", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"A", "B", "C", "D", "E"},
			ScrollOffset: 0,
		}

		// Terminal height 20 → max window = 15
		// 5 lines fit entirely in viewport, should not scroll
		co.ScrollDown(20)

		if co.ScrollOffset != 0 {
			t.Errorf("ScrollOffset = %d, want 0 (should not scroll when content fits)", co.ScrollOffset)
		}
	})

	t.Run("scroll down to maximum", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"A", "B", "C", "D", "E", "F", "G", "H", "I", "J"},
			ScrollOffset: 0,
		}

		// Terminal height 16 → max window = 12
		// 10 lines total, can scroll down until offset + 12 >= 10
		// Max offset = 10 - 12 = -2, but we can't go negative
		// Actually: can scroll while (offset + 12) < 10
		// So max offset before stopping = 10 - 12 = can't scroll at all? Let me recalculate
		// offset=0: show lines 0-11 (but only 10 exist) → shows all 10
		// Can't scroll since viewport > content

		// Let's use different numbers: 20 lines, window of 12
		lines := make([]string, 20)
		for i := range lines {
			lines[i] = string(rune('A' + i))
		}
		co.Lines = lines

		// Max scroll: offset + 12 < 20 → offset < 8 → max offset = 7
		// But the function allows offset until (offset + 12) < 20
		// So when offset = 8, offset + 12 = 20, not < 20, stops
		for i := 0; i < 20; i++ {
			co.ScrollDown(16)
		}

		// Maximum offset should be 8 (showing lines 8-19, which is 12 lines)
		want := 8
		if co.ScrollOffset != want {
			t.Errorf("ScrollOffset = %d after scrolling to max, want %d", co.ScrollOffset, want)
		}
	})

	t.Run("scroll down at maximum has no effect", func(t *testing.T) {
		lines := make([]string, 20)
		for i := range lines {
			lines[i] = string(rune('A' + i))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 8, // Already at max for height 16 (window 12)
		}

		co.ScrollDown(16)

		if co.ScrollOffset != 8 {
			t.Errorf("ScrollOffset = %d, want 8 (should not scroll past end)", co.ScrollOffset)
		}
	})

	t.Run("scroll with different terminal heights", func(t *testing.T) {
		lines := make([]string, 100)
		for i := range lines {
			lines[i] = string(rune('A' + (i % 26)))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 0,
		}

		// Small terminal (height 40 → window 30)
		co.ScrollDown(40)
		if co.ScrollOffset != 1 {
			t.Errorf("ScrollOffset = %d for height 40, want 1", co.ScrollOffset)
		}

		// Reset
		co.ScrollOffset = 0

		// Large terminal (height 200 → window 150)
		co.ScrollDown(200)
		if co.ScrollOffset != 0 {
			t.Errorf("ScrollOffset = %d for height 200, want 0 (content fits entirely)", co.ScrollOffset)
		}
	})
}

// TestCommandOutputScrollUp tests the ScrollUp() method
func TestCommandOutputScrollUp(t *testing.T) {
	t.Run("scroll up from offset", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"A", "B", "C", "D", "E"},
			ScrollOffset: 3,
		}

		co.ScrollUp()

		if co.ScrollOffset != 2 {
			t.Errorf("ScrollOffset = %d after ScrollUp, want 2", co.ScrollOffset)
		}
	})

	t.Run("scroll up multiple times", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"A", "B", "C", "D", "E"},
			ScrollOffset: 5,
		}

		for i := 0; i < 3; i++ {
			co.ScrollUp()
		}

		if co.ScrollOffset != 2 {
			t.Errorf("ScrollOffset = %d after 3 ScrollUp calls, want 2", co.ScrollOffset)
		}
	})

	t.Run("cannot scroll up past zero", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"A", "B", "C", "D", "E"},
			ScrollOffset: 0,
		}

		co.ScrollUp()

		if co.ScrollOffset != 0 {
			t.Errorf("ScrollOffset = %d, want 0 (should not go negative)", co.ScrollOffset)
		}
	})

	t.Run("scroll up to zero", func(t *testing.T) {
		co := &CommandOutput{
			Lines:        []string{"A", "B", "C", "D", "E"},
			ScrollOffset: 3,
		}

		// Scroll up 3 times to reach 0
		for i := 0; i < 3; i++ {
			co.ScrollUp()
		}

		if co.ScrollOffset != 0 {
			t.Errorf("ScrollOffset = %d after scrolling to top, want 0", co.ScrollOffset)
		}

		// Try scrolling up one more time
		co.ScrollUp()

		if co.ScrollOffset != 0 {
			t.Errorf("ScrollOffset = %d after scrolling past top, want 0", co.ScrollOffset)
		}
	})

	t.Run("scroll up from large offset", func(t *testing.T) {
		lines := make([]string, 100)
		for i := range lines {
			lines[i] = string(rune('A' + (i % 26)))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 50,
		}

		co.ScrollUp()

		if co.ScrollOffset != 49 {
			t.Errorf("ScrollOffset = %d after ScrollUp, want 49", co.ScrollOffset)
		}
	})
}

// TestCommandOutputScrollingIntegration tests combined scrolling behavior
func TestCommandOutputScrollingIntegration(t *testing.T) {
	t.Run("scroll down and up", func(t *testing.T) {
		lines := make([]string, 50)
		for i := range lines {
			lines[i] = string(rune('A' + (i % 26)))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 0,
		}

		termHeight := 40 // max window = 30

		// Scroll down 5 times
		for i := 0; i < 5; i++ {
			co.ScrollDown(termHeight)
		}

		if co.ScrollOffset != 5 {
			t.Errorf("ScrollOffset = %d after 5 down, want 5", co.ScrollOffset)
		}

		// Scroll up 2 times
		for i := 0; i < 2; i++ {
			co.ScrollUp()
		}

		if co.ScrollOffset != 3 {
			t.Errorf("ScrollOffset = %d after 2 up, want 3", co.ScrollOffset)
		}

		// Scroll back to top
		for i := 0; i < 10; i++ {
			co.ScrollUp()
		}

		if co.ScrollOffset != 0 {
			t.Errorf("ScrollOffset = %d after scrolling to top, want 0", co.ScrollOffset)
		}
	})

	t.Run("scroll to bottom and back to top", func(t *testing.T) {
		lines := make([]string, 30)
		for i := range lines {
			lines[i] = string(rune('A' + i))
		}

		co := &CommandOutput{
			Lines:        lines,
			ScrollOffset: 0,
		}

		termHeight := 28 // max window = 21

		// Scroll to bottom (max offset = 30 - 21 = 9)
		for i := 0; i < 20; i++ {
			co.ScrollDown(termHeight)
		}

		want := 9
		if co.ScrollOffset != want {
			t.Errorf("ScrollOffset = %d after scrolling to bottom, want %d", co.ScrollOffset, want)
		}

		// Verify viewport shows last lines
		viewport := co.Viewport(termHeight)
		if len(viewport) != 21 {
			t.Errorf("Viewport length = %d, want 21", len(viewport))
		}
		if viewport[len(viewport)-1] != string(rune('A'+29)) {
			t.Errorf("Last viewport line = %q, want %q", viewport[len(viewport)-1], string(rune('A'+29)))
		}

		// Scroll back to top
		for i := 0; i < 20; i++ {
			co.ScrollUp()
		}

		if co.ScrollOffset != 0 {
			t.Errorf("ScrollOffset = %d after scrolling back to top, want 0", co.ScrollOffset)
		}
	})
}