package core

import "testing"

// --------------------------------------------------
// Buffer Tests (generated by ClaudeCode)
// --------------------------------------------------

func TestBuffer_InsertLine(t *testing.T) {
	t.Run("inserts at beginning", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"line 1", "line 2"}).
			Build()

		buf.InsertLine(0, "new line")

		if buf.LineCount() != 3 {
			t.Errorf("expected 3 lines, got %d", buf.LineCount())
		}
		if buf.Line(0) != "new line" {
			t.Errorf("expected 'new line', got '%s'", buf.Line(0))
		}
		if buf.Line(1) != "line 1" {
			t.Errorf("expected 'line 1' at index 1, got '%s'", buf.Line(1))
		}
	})

	t.Run("inserts at end", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"line 1", "line 2"}).
			Build()

		buf.InsertLine(2, "new line")

		if buf.LineCount() != 3 {
			t.Errorf("expected 3 lines, got %d", buf.LineCount())
		}
		if buf.Line(2) != "new line" {
			t.Errorf("expected 'new line' at end, got '%s'", buf.Line(2))
		}
	})

	t.Run("inserts in middle", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"line 1", "line 3"}).
			Build()

		buf.InsertLine(1, "line 2")

		if buf.LineCount() != 3 {
			t.Errorf("expected 3 lines, got %d", buf.LineCount())
		}
		if buf.Line(1) != "line 2" {
			t.Errorf("expected 'line 2' at index 1, got '%s'", buf.Line(1))
		}
	})

	t.Run("handles empty buffer", func(t *testing.T) {
		buf := NewBufferBuilder().Build()

		buf.InsertLine(0, "first line")

		if buf.LineCount() != 2 { // Original empty line + new line
			t.Errorf("expected 2 lines, got %d", buf.LineCount())
		}
	})
}

func TestBuffer_DeleteLine(t *testing.T) {
	t.Run("deletes from beginning", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"DELETE ME", "line 2", "line 3"}).
			Build()

		buf.DeleteLine(0)

		if buf.LineCount() != 2 {
			t.Errorf("expected 2 lines, got %d", buf.LineCount())
		}
		if buf.Line(0) != "line 2" {
			t.Errorf("expected 'line 2' at index 0, got '%s'", buf.Line(0))
		}
	})

	t.Run("deletes from middle", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"line 1", "DELETE ME", "line 3"}).
			Build()

		buf.DeleteLine(1)

		if buf.LineCount() != 2 {
			t.Errorf("expected 2 lines, got %d", buf.LineCount())
		}
		if buf.Line(1) != "line 3" {
			t.Errorf("expected 'line 3' at index 1, got '%s'", buf.Line(1))
		}
	})

	t.Run("deletes from end", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"line 1", "line 2", "DELETE ME"}).
			Build()

		buf.DeleteLine(2)

		if buf.LineCount() != 2 {
			t.Errorf("expected 2 lines, got %d", buf.LineCount())
		}
		if buf.Line(1) != "line 2" {
			t.Errorf("expected 'line 2' at index 1, got '%s'", buf.Line(1))
		}
	})

	t.Run("can delete all lines", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"only line"}).
			Build()

		buf.DeleteLine(0)

		// Buffer allows being completely empty (0 lines)
		if buf.LineCount() != 0 {
			t.Errorf("expected 0 lines after deleting last line, got %d", buf.LineCount())
		}
	})
}

func TestBuffer_SetLine(t *testing.T) {
	t.Run("updates existing line", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"old content"}).
			Build()

		buf.SetLine(0, "new content")

		if buf.Line(0) != "new content" {
			t.Errorf("expected 'new content', got '%s'", buf.Line(0))
		}
	})

	t.Run("updates middle line", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"line 1", "old", "line 3"}).
			Build()

		buf.SetLine(1, "new")

		if buf.Line(1) != "new" {
			t.Errorf("expected 'new', got '%s'", buf.Line(1))
		}
		// Verify other lines unchanged
		if buf.Line(0) != "line 1" {
			t.Error("line 0 should be unchanged")
		}
		if buf.Line(2) != "line 3" {
			t.Error("line 2 should be unchanged")
		}
	})

	t.Run("can set to empty string", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"has content"}).
			Build()

		buf.SetLine(0, "")

		if buf.Line(0) != "" {
			t.Errorf("expected empty line, got '%s'", buf.Line(0))
		}
	})
}

func TestBuffer_LineCount(t *testing.T) {
	t.Run("empty buffer has one line", func(t *testing.T) {
		buf := NewBufferBuilder().Build()

		if buf.LineCount() != 1 {
			t.Errorf("expected 1 line in empty buffer, got %d", buf.LineCount())
		}
	})

	t.Run("counts multiple lines", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"a", "b", "c", "d", "e"}).
			Build()

		if buf.LineCount() != 5 {
			t.Errorf("expected 5 lines, got %d", buf.LineCount())
		}
	})

	t.Run("counts after insertions", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"line 1"}).
			Build()

		buf.InsertLine(1, "line 2")
		buf.InsertLine(2, "line 3")

		if buf.LineCount() != 3 {
			t.Errorf("expected 3 lines, got %d", buf.LineCount())
		}
	})

	t.Run("counts after deletions", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"a", "b", "c", "d", "e"}).
			Build()

		buf.DeleteLine(2)
		buf.DeleteLine(2)

		if buf.LineCount() != 3 {
			t.Errorf("expected 3 lines after 2 deletions, got %d", buf.LineCount())
		}
	})
}

func TestBuffer_Line(t *testing.T) {
	t.Run("retrieves correct line", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"first", "second", "third"}).
			Build()

		if buf.Line(0) != "first" {
			t.Errorf("expected 'first', got '%s'", buf.Line(0))
		}
		if buf.Line(1) != "second" {
			t.Errorf("expected 'second', got '%s'", buf.Line(1))
		}
		if buf.Line(2) != "third" {
			t.Errorf("expected 'third', got '%s'", buf.Line(2))
		}
	})

	t.Run("handles special characters", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"hello\tworld", "foo\nbar"}).
			Build()

		if buf.Line(0) != "hello\tworld" {
			t.Errorf("expected tabs preserved, got '%s'", buf.Line(0))
		}
	})

	t.Run("handles unicode", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"hello 世界", "emoji 🎉"}).
			Build()

		if buf.Line(0) != "hello 世界" {
			t.Errorf("expected unicode preserved, got '%s'", buf.Line(0))
		}
		if buf.Line(1) != "emoji 🎉" {
			t.Errorf("expected emoji preserved, got '%s'", buf.Line(1))
		}
	})
}

func TestBufferBuilder(t *testing.T) {
	t.Run("builds with default values", func(t *testing.T) {
		buf := NewBufferBuilder().Build()

		if buf.LineCount() != 1 {
			t.Errorf("expected 1 empty line, got %d", buf.LineCount())
		}
		if buf.Filename != "" {
			t.Errorf("expected empty filename, got '%s'", buf.Filename)
		}
	})

	t.Run("builds with custom lines", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithLines([]string{"line 1", "line 2"}).
			Build()

		if buf.LineCount() != 2 {
			t.Errorf("expected 2 lines, got %d", buf.LineCount())
		}
	})

	t.Run("builds with filename", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithFilename("test.txt").
			Build()

		if buf.Filename != "test.txt" {
			t.Errorf("expected filename 'test.txt', got '%s'", buf.Filename)
		}
	})

	t.Run("builds with filetype", func(t *testing.T) {
		buf := NewBufferBuilder().
			WithFiletype("go").
			Build()

		if buf.Filetype != "go" {
			t.Errorf("expected filetype 'go', got '%s'", buf.Filetype)
		}
	})
}