package editor

import (
	"testing"
	"time"

	"github.com/gdamore/tcell/v2"
)

// clickingView returns a view onto text with a clock the test drives, so a
// double click is a matter of what the test says rather than of how fast the
// machine is.
func clickingView(t *testing.T, text string) (*View, tcell.SimulationScreen, *time.Time) {
	t.Helper()

	view, screen, _ := newTestView(t, text, 40, 8)
	moment := time.Date(2026, 9, 2, 12, 0, 0, 0, time.UTC)
	view.SetClock(func() time.Time { return moment })
	return view, screen, &moment
}

// press sends one button-down at a cell, then the button-up that ends it.
func pressAt(view *View, x, y int) {
	view.HandleMouse(tcell.NewEventMouse(x, y, tcell.Button1, tcell.ModNone))
	view.HandleMouse(tcell.NewEventMouse(x, y, tcell.ButtonNone, tcell.ModNone))
}

func TestADoubleClickSelectsTheWord(t *testing.T) {
	view, _, _ := clickingView(t, "func mainLoop() {}\n")
	x := view.gutterWidth() + 8 // inside "mainLoop"

	pressAt(view, x, 0)
	pressAt(view, x, 0)

	if got := view.Buffer().SelectedText(); got != "mainLoop" {
		t.Errorf("the selection is %q, want %q", got, "mainLoop")
	}
}

func TestASingleClickSelectsNothing(t *testing.T) {
	view, _, _ := clickingView(t, "func mainLoop() {}\n")

	pressAt(view, view.gutterWidth()+8, 0)

	if got := view.Buffer().SelectedText(); got != "" {
		t.Errorf("one click selected %q", got)
	}
}

func TestTwoSlowClicksAreTwoClicks(t *testing.T) {
	// Two unrelated clicks in the same place happen all the time while
	// reading, and selecting a word each time would be noise.
	view, _, moment := clickingView(t, "func mainLoop() {}\n")
	x := view.gutterWidth() + 8

	pressAt(view, x, 0)
	*moment = moment.Add(doubleClickWithin + time.Millisecond)
	pressAt(view, x, 0)

	if got := view.Buffer().SelectedText(); got != "" {
		t.Errorf("two clicks %v apart selected %q", doubleClickWithin, got)
	}
}

func TestTwoClicksOnDifferentCellsAreTwoClicks(t *testing.T) {
	// A press one column over is a different word, and selecting the first
	// because the pointer drifted is worse than selecting nothing.
	view, _, _ := clickingView(t, "alpha beta\n")

	pressAt(view, view.gutterWidth()+1, 0)
	pressAt(view, view.gutterWidth()+2, 0)

	if got := view.Buffer().SelectedText(); got != "" {
		t.Errorf("two clicks on different cells selected %q", got)
	}
}

func TestADragIsNotASecondClick(t *testing.T) {
	// tcell sends Button1 for every event of a drag. Counting those would
	// turn a slow drag into a double click halfway through.
	view, _, _ := clickingView(t, "alpha beta gamma\n")
	x := view.gutterWidth()

	view.HandleMouse(tcell.NewEventMouse(x+1, 0, tcell.Button1, tcell.ModNone))
	for column := 2; column <= 9; column++ {
		view.HandleMouse(tcell.NewEventMouse(x+column, 0, tcell.Button1, tcell.ModNone))
	}
	view.HandleMouse(tcell.NewEventMouse(x+9, 0, tcell.ButtonNone, tcell.ModNone))

	if got := view.Buffer().SelectedText(); got != "lpha bet" {
		t.Errorf("the drag selected %q, want the characters it crossed", got)
	}
}

func TestADoubleClickOffAWordSelectsNothing(t *testing.T) {
	view, _, _ := clickingView(t, "alpha beta\n")
	x := view.gutterWidth() + 5 // the space

	pressAt(view, x, 0)
	pressAt(view, x, 0)

	if got := view.Buffer().SelectedText(); got != "" {
		t.Errorf("a double click on a space selected %q", got)
	}
}

func TestHoldingAfterADoubleClickExtendsFromTheWordsStart(t *testing.T) {
	// Not the word-by-word drag a large editor does — the cheap half of it.
	// The alternative is the word collapsing back to a single character the
	// moment the pointer twitches, which is worse than either.
	view, _, _ := clickingView(t, "alpha beta\n")
	x := view.gutterWidth() + 1

	pressAt(view, x, 0)                                                         // first click, released
	view.HandleMouse(tcell.NewEventMouse(x, 0, tcell.Button1, tcell.ModNone))   // second, and held
	view.HandleMouse(tcell.NewEventMouse(x+7, 0, tcell.Button1, tcell.ModNone)) // dragged
	view.HandleMouse(tcell.NewEventMouse(x+7, 0, tcell.ButtonNone, tcell.ModNone))

	if got := view.Buffer().SelectedText(); got != "alpha be" {
		t.Errorf("dragging after a double click left %q, want it extended from the word's start", got)
	}
}

func TestAThirdClickIsCountedButDoesNothingYet(t *testing.T) {
	// The counter keeps going so that a triple click can be given a meaning
	// later without reworking any of this. Today it selects the word again.
	view, _, _ := clickingView(t, "alpha beta\n")
	x := view.gutterWidth() + 1

	pressAt(view, x, 0)
	pressAt(view, x, 0)
	pressAt(view, x, 0)

	if got := view.lastClick.count; got != 3 {
		t.Errorf("the click count is %d, want 3", got)
	}
	if got := view.Buffer().SelectedText(); got != "alpha" {
		t.Errorf("the third click left %q selected", got)
	}
}