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package editor

import (
	"testing"

	tea "github.com/charmbracelet/bubbletea"
)

func altUp(e *Editor)   { e.HandleKey(tea.KeyMsg{Type: tea.KeyUp, Alt: true}) }
func altDown(e *Editor) { e.HandleKey(tea.KeyMsg{Type: tea.KeyDown, Alt: true}) }

func TestMoveLineUpSwapsWithLineAbove(t *testing.T) {
	e := New()
	e.SetContent([]byte("a\nb\nc"))
	e.Cursor = Position{Row: 1, Col: 1}
	if !e.MoveLineUp() {
		t.Fatal("MoveLineUp returned false")
	}
	if e.Lines[0] != "b" || e.Lines[1] != "a" {
		t.Fatalf("lines = %q, want [b a c]", e.Lines)
	}
	if e.Cursor.Row != 0 || e.Cursor.Col != 1 {
		t.Fatalf("cursor = %+v, want row 0 col 1 (follows the moved line)", e.Cursor)
	}
}

func TestMoveLineDownSwapsWithLineBelow(t *testing.T) {
	e := New()
	e.SetContent([]byte("a\nb\nc"))
	e.Cursor = Position{Row: 1, Col: 1}
	if !e.MoveLineDown() {
		t.Fatal("MoveLineDown returned false")
	}
	if e.Lines[1] != "c" || e.Lines[2] != "b" {
		t.Fatalf("lines = %q, want [a c b]", e.Lines)
	}
	if e.Cursor.Row != 2 || e.Cursor.Col != 1 {
		t.Fatalf("cursor = %+v, want row 2 col 1", e.Cursor)
	}
}

func TestMoveLineUpNoOpAtTop(t *testing.T) {
	e := New()
	e.SetContent([]byte("a\nb"))
	e.Cursor = Position{Row: 0, Col: 0}
	if e.MoveLineUp() {
		t.Fatal("MoveLineUp at top should be a no-op")
	}
	if e.Lines[0] != "a" || e.Lines[1] != "b" {
		t.Fatalf("lines = %q, want unchanged", e.Lines)
	}
}

func TestMoveLineDownNoOpAtBottom(t *testing.T) {
	e := New()
	e.SetContent([]byte("a\nb"))
	e.Cursor = Position{Row: 1, Col: 0}
	if e.MoveLineDown() {
		t.Fatal("MoveLineDown at bottom should be a no-op")
	}
	if e.Lines[0] != "a" || e.Lines[1] != "b" {
		t.Fatalf("lines = %q, want unchanged", e.Lines)
	}
}

// Repeated presses walk a line several positions in one direction.
func TestMoveLineUpRepeatsWalkUp(t *testing.T) {
	e := New()
	e.SetContent([]byte("a\nb\nc\nd"))
	e.Cursor = Position{Row: 3, Col: 0} // "d"
	altUp(e)
	altUp(e)
	altUp(e)
	if e.Lines[0] != "d" {
		t.Fatalf("lines = %q, want d walked to top", e.Lines)
	}
	if e.Cursor.Row != 0 {
		t.Fatalf("cursor row = %d, want 0", e.Cursor.Row)
	}
}

// Each move is one undo step that reverts exactly one swap.
func TestMoveLineDownIsOneUndoStep(t *testing.T) {
	e := New()
	e.SetContent([]byte("a\nb\nc"))
	e.Cursor = Position{Row: 0, Col: 0}
	altDown(e)
	if e.Lines[0] != "b" || e.Lines[1] != "a" {
		t.Fatalf("after move lines = %q, want [b a c]", e.Lines)
	}
	e.Undo()
	if e.Lines[0] != "a" || e.Lines[1] != "b" || e.Lines[2] != "c" {
		t.Fatalf("after undo lines = %q, want [a b c]", e.Lines)
	}
}

// A move past the document edge records no undo checkpoint (no-op key).
func TestMoveLineUpAtTopRecordsNoUndo(t *testing.T) {
	e := New()
	e.SetContent([]byte("a\nb"))
	e.Cursor = Position{Row: 0, Col: 0}
	altUp(e)
	if len(e.undo) != 0 {
		t.Fatalf("undo stack = %d, want 0 (no-op move records nothing)", len(e.undo))
	}
}