//go:build e2e

package e2e

import (
	"testing"

	"github.com/mxschmitt/playwright-go"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// TestEmbed_PlaceholderGivesWayToOneOwnedIframe covers #2192 together with the placeholder
// support #2002 added. createInstance took root.firstElementChild as its iframe, so anything the
// integrator left in the root was adopted instead: a <noscript> fallback became "the iframe",
// createIframe never ran, and the height messages went to an element that cannot show comments.
// The same defect defeated the placeholder promise, since an element placeholder is mistaken for
// the iframe and inited never arrives to clear it.
//
// A text node and an element, because only the element was ever adopted and a test carrying text
// alone passes against the defect.
func TestEmbed_PlaceholderGivesWayToOneOwnedIframe(t *testing.T) {
	page := newPage(t)
	stubSignedOut(t, page)
	embedConfig(t, page, map[string]any{},
		`loading the comments`, `<div id="element-placeholder">a spinner of the integrator's own</div>`)

	widget(t, page)

	// the placeholder goes only when the document reports itself inited, so reaching this means
	// the message arrived from a real widget document and not from an adopted div
	waitHidden(t, page.Locator("#element-placeholder"),
		"the element placeholder survived, so the widget never reported itself inited")

	frames, err := page.Locator("#remark42 iframe").Count()
	require.NoError(t, err)
	assert.Equal(t, 1, frames, "the root should hold exactly the one iframe the embed created")

	owned, err := page.Locator("#remark42 iframe[data-remark42-iframe]").Count()
	require.NoError(t, err)
	assert.Equal(t, 1, owned, "the iframe is not marked as the embed's own, so the next "+
		"createInstance cannot tell it from whatever else is in the root")

	text, err := page.Locator("#remark42").InnerText()
	require.NoError(t, err)
	assert.NotContains(t, text, "loading the comments", "the text placeholder was never cleared")

	// a second instance has to reuse the marked iframe, not add another. this is what a
	// single-page app does on every navigation
	_, err = page.Evaluate(`() => window.REMARK42.createInstance(window.remark_config)`)
	require.NoError(t, err)

	frames, err = page.Locator("#remark42 iframe").Count()
	require.NoError(t, err)
	assert.Equal(t, 1, frames, "a second createInstance added an iframe instead of reusing the one there")
}

// TestEmbed_DestroyRemovesTheWidgetAndCreateInstanceBringsItBack covers the rest of the surface a
// single-page app holds, documented in configuration/frontend/spa.md and exercised by nothing.
// Neither half is observable from inside the widget, which is where the rest of this suite looks
func TestEmbed_DestroyRemovesTheWidgetAndCreateInstanceBringsItBack(t *testing.T) {
	page := newPage(t)
	stubSignedOut(t, page)
	embedConfig(t, page, map[string]any{})
	widget(t, page)

	_, err := page.Evaluate(`() => window.REMARK42.destroy()`)
	require.NoError(t, err)

	waitHidden(t, page.Locator("#remark42 iframe"), "destroy left the iframe in the page")

	// and destroy drops the two functions it documents dropping, so a caller can tell a live
	// instance from a destroyed one
	live, err := page.Evaluate(`() => typeof window.REMARK42.destroy`)
	require.NoError(t, err)
	assert.Equal(t, "undefined", live, "destroy left its own handle behind")

	_, err = page.Evaluate(`() => window.REMARK42.createInstance(window.remark_config)`)
	require.NoError(t, err)
	widget(t, page)
}

// TestEmbed_ThemeChangesReachTheWidgetAfterLoad covers the runtime half of the color-scheme
// contract. The iframe cases assert what a load with a theme parameter produces; this is the
// path the demo page's own toggle takes, and the one an integrator calls when a reader switches
// themes on the host page
func TestEmbed_ThemeChangesReachTheWidgetAfterLoad(t *testing.T) {
	page := newPage(t)
	stubSignedOut(t, page)
	embedConfig(t, page, map[string]any{"theme": "light"})
	widget(t, page)

	require.Equal(t, "light", widgetColorScheme(t, page), "the widget did not start in the theme it was given")

	_, err := page.Evaluate(`() => window.REMARK42.changeTheme('dark')`)
	require.NoError(t, err)

	// both sides, since it is the disagreement between them that paints the opaque canvas the
	// iframe cases are about
	eventually(t, waitTimeout, "the widget document never took the new theme", func() bool {
		return widgetColorScheme(t, page) == "dark"
	})

	onElement, err := page.Evaluate(`() => document.querySelector('#remark42 iframe').style.colorScheme`)
	require.NoError(t, err)
	assert.Equal(t, "dark", onElement, "the parent left the old scheme on the iframe element")
}

// widgetColorScheme is the color-scheme in force inside the widget document
func widgetColorScheme(t *testing.T, page playwright.Page) string {
	t.Helper()

	v, err := page.FrameLocator("#remark42 iframe").Locator(":root").Evaluate(
		`(el) => getComputedStyle(el).colorScheme`, nil,
		playwright.LocatorEvaluateOptions{Timeout: playwright.Float(float64(pollTimeout.Milliseconds()))})
	if err != nil {
		return ""
	}
	scheme, _ := v.(string)
	return scheme
}