package terrace

import (
	"io"
	"testing"
)

// MockReader is a mock implementation of the Reader interface for testing.
type MockReader struct {
	lines []string
	index int
}

// Read returns the next line from the mock reader.
func (r *MockReader) Read() (string, error) {
	if r.index >= len(r.lines) {
		return "", io.EOF
	}
	line := r.lines[r.index]
	r.index++
	return line, nil
}

func TestTerraceDocument(t *testing.T) {
	tests := []struct {
		name  string
		lines []string
	}{
		{
			name:  "simple document",
			lines: []string{"hello world", "  child1", "  child2", "another top-level"},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			reader := &MockReader{lines: tt.lines}
			doc := NewTerraceDocument(reader, ' ')

			// Read all nodes
			var nodes []*TerraceNode
			for {
				node, err := doc.Next()
				if err == io.EOF {
					break
				}
				if err != nil {
					t.Fatalf("Unexpected error: %v", err)
				}
				nodes = append(nodes, node)
			}

			if len(nodes) != len(tt.lines) {
				t.Errorf("Expected %d nodes, but got %d", len(tt.lines), len(nodes))
			}

			// Push back a node
			if len(nodes) > 0 {
				lastNode := nodes[len(nodes)-1]
				doc.PushBack(lastNode)

				node, err := doc.Next()
				if err != nil {
					t.Fatalf("Unexpected error: %v", err)
				}

				if node != lastNode {
					t.Errorf("Expected to read the pushed back node")
				}
			}
		})
	}
}

func TestTerraceNode(t *testing.T) {
	lineData := &LineData{Indent: ' ', Level: 2, OffsetHead: 2, OffsetTail: 7}
	node := &TerraceNode{
		lineData:   lineData,
		content:    "  hello world",
		lineNumber: 1,
	}

	if node.Head() != "hello" {
		t.Errorf("Expected head to be 'hello', but got '%s'", node.Head())
	}

	if node.Tail() != "world" {
		t.Errorf("Expected tail to be 'world', but got '%s'", node.Tail())
	}

	if node.Content() != "hello world" {
		t.Errorf("Expected content to be 'hello world', but got '%s'", node.Content())
	}

	if node.Level() != 2 {
		t.Errorf("Expected level to be 2, but got %d", node.Level())
	}

	if node.LineNumber() != 1 {
		t.Errorf("Expected line number to be 1, but got %d", node.LineNumber())
	}
}