//go:build browser

// The presenting screens with their script on. The Go tests read the
// markup; only a browser runs static/present.js against it, and the
// failure this file was written for (polish audit B3, 2026-09-23) was
// the script and the markup disagreeing: the presenter view and the
// remote carried no data-slide, so the page believed it was on slide
// 0, the stream's first event said slide 1, and the page reloaded —
// and did the same on every load after, about fifty times a second.
package slidestest

import (
	"fmt"
	"regexp"
	"sync/atomic"
	"testing"
	"time"

	"github.com/chromedp/cdproto/emulation"
	"github.com/chromedp/cdproto/page"
	"github.com/chromedp/chromedp"
	"github.com/chromedp/chromedp/kb"
)

// TestBrowserProjectorFitsTheViewport keeps the projector a stage rather
// than a long document: its slide is bounded by the viewport and its
// controls are overlaid where the presenter can still reach them.
func TestBrowserProjectorFitsTheViewport(t *testing.T) {
	rig, mailer := newRig(t)
	browserSignIn(t, rig, mailer)

	var deck string
	rig.Run(chromedp.Evaluate(`(document.querySelector('a[href^="/d/"]')?.getAttribute('href') ?? '')`, &deck))
	if !deckPath.MatchString(deck) {
		t.Fatalf("the deck list links no deck: %q", deck)
	}

	var path string
	rig.Run(
		chromedp.Navigate(rig.Origin+deck),
		chromedp.Click(`form[action$="/present"] button`, chromedp.ByQuery),
		waitFor(`location.pathname.endsWith('/notes')`),
		chromedp.Evaluate(`location.pathname + location.search`, &path),
	)
	m := notesLocation.FindStringSubmatch(path)
	if m == nil {
		t.Fatalf("Present landed on %q, want /p/{session}/notes?t={token}", path)
	}

	for _, viewport := range []struct{ width, height int }{{1920, 1080}, {1280, 720}} {
		t.Run(fmt.Sprintf("%dx%d", viewport.width, viewport.height), func(t *testing.T) {
			var geometry struct {
				ScrollHeight float64 `json:"scrollHeight"`
				Viewport     float64 `json:"viewport"`
				ScrollY      float64 `json:"scrollY"`
				Top          float64 `json:"top"`
				Bottom       float64 `json:"bottom"`
			}
			rig.Run(
				emulation.SetDeviceMetricsOverride(int64(viewport.width), int64(viewport.height), 1, false),
				chromedp.Navigate(rig.Origin+m[1]+"?t="+m[2]),
				chromedp.WaitVisible(`[slides-bar]`, chromedp.ByQuery),
				chromedp.Evaluate(`(() => {
					window.scrollTo(0, 1);
					const controls = document.querySelector('[slides-bar]').getBoundingClientRect();
					return {
						scrollHeight: document.documentElement.scrollHeight,
						viewport: window.innerHeight,
						scrollY: window.scrollY,
						top: controls.top,
						bottom: controls.bottom,
					};
				})()`, &geometry),
			)
			if geometry.ScrollHeight > geometry.Viewport || geometry.ScrollY != 0 {
				t.Errorf("projector scrolls: document %.0fpx, viewport %.0fpx, scrollY %.0f", geometry.ScrollHeight, geometry.Viewport, geometry.ScrollY)
			}
			if geometry.Top < 0 || geometry.Bottom > geometry.Viewport {
				t.Errorf("controls are outside the viewport: top %.0fpx, bottom %.0fpx, viewport %.0fpx", geometry.Top, geometry.Bottom, geometry.Viewport)
			}
		})
	}
}

var notesLocation = regexp.MustCompile(`^(/p/[23456789abcdefghjkmnpqrstuvwxyz]{10})/notes\?t=([A-Za-z0-9_-]{43})$`)

// TestBrowserPresentingScreensHoldStill: the presenter view and the
// phone remote each load once and then stay put while nothing
// changes, and each reloads exactly once when the slide does move —
// which is how those two pages follow a talk (present.js reloads them
// rather than re-rendering two slides and the notes itself).
func TestBrowserPresentingScreensHoldStill(t *testing.T) {
	rig, mailer := newRig(t)
	browserSignIn(t, rig, mailer)

	// Every top-level navigation the tab makes, reloads included.
	var loads atomic.Int64
	chromedp.ListenTarget(rig.Context(), func(ev any) {
		if e, ok := ev.(*page.EventFrameNavigated); ok && e.Frame.ParentID == "" {
			loads.Add(1)
		}
	})

	var deck string
	rig.Run(chromedp.Evaluate(`(document.querySelector('a[href^="/d/"]')?.getAttribute('href') ?? '')`, &deck))
	if !deckPath.MatchString(deck) {
		t.Fatalf("the deck list links no deck: %q", deck)
	}

	var path string
	rig.Run(
		chromedp.Navigate(rig.Origin+deck),
		chromedp.Click(`form[action$="/present"] button`, chromedp.ByQuery),
		waitFor(`location.pathname.endsWith('/notes')`),
		chromedp.Evaluate(`location.pathname + location.search`, &path),
	)
	m := notesLocation.FindStringSubmatch(path)
	if m == nil {
		t.Fatalf("Present landed on %q, want /p/{session}/notes?t={token}", path)
	}
	session, token := m[1], m[2]

	// holdsStill waits for the page to settle and the stream to have
	// said its piece (one event on connect), then counts loads over a
	// window long enough for the broken page to have reloaded hundreds
	// of times.
	holdsStill := func(name string) {
		t.Helper()
		rig.Run(chromedp.Sleep(1500 * time.Millisecond))
		before := loads.Load()
		rig.Run(chromedp.Sleep(3 * time.Second))
		if n := loads.Load() - before; n != 0 {
			t.Errorf("the %s loaded %d more times in 3s with nothing changing, want 0", name, n)
		}
		// And it holds still because it knows where it is, not only
		// because present.js refuses to reload twice for one slide:
		// the script's root names the slide the counter shows.
		var marked, counter string
		rig.Run(
			chromedp.Evaluate(`document.querySelector('[data-session]')?.getAttribute('data-slide') ?? 'missing'`, &marked),
			chromedp.Evaluate(`(document.querySelector('[slides-counter]')?.textContent ?? '').trim().split(' ')[0]`, &counter),
		)
		if marked != counter {
			t.Errorf("the %s's script root says data-slide=%q; the counter shows slide %q", name, marked, counter)
		}
	}
	// movesOnce presses the right arrow — present.js posts `next` — and
	// the page must reload onto the new slide once, and only once.
	movesOnce := func(name, counter string) {
		t.Helper()
		before := loads.Load()
		rig.Run(
			chromedp.KeyEvent(kb.ArrowRight),
			waitFor(`document.querySelector('[slides-counter]')?.textContent.trim().startsWith('`+counter+` /')`),
			chromedp.Sleep(3*time.Second),
		)
		if n := loads.Load() - before; n != 1 {
			t.Errorf("the %s loaded %d times after one slide change, want exactly 1", name, n)
		}
	}

	holdsStill("presenter view")
	rig.Screen("body", "presenter view")
	movesOnce("presenter view", "2")

	rig.Run(chromedp.Navigate(rig.Origin + session + "/remote?t=" + token))
	holdsStill("remote")
	rig.Screen("body", "remote")
	movesOnce("remote", "3")
}