//go:build browser

package gallery

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"testing"
	"time"

	"github.com/chromedp/chromedp"

	"amadan.net/rastrillo/fiesta"
	"amadan.net/rastrillo/fiesta/internal/harness"
)

// The shell demos are the layout examples' frame documents opened full
// width, and they are the shell as an app gets it. Rastrillo's two
// drives on its shell demos, ported onto the layout documents.

// layoutDemos is every layout document's path in the tree, in day and
// English: the shell demos.
func layoutDemos(t *testing.T) []string {
	t.Helper()
	var out []string
	for _, e := range manifest(t).Examples {
		if e.Document {
			out = append(out, frameFile(fiesta.ThemeNames()[0], "en", e.Name, e.Default))
		}
	}
	if len(out) == 0 {
		t.Fatal("the manifest has no layout example; the drives below would read nothing")
	}
	return out
}

// mouseRig is a browser with a mouse, serving the tree.
func mouseRig(t *testing.T) *harness.Rig {
	t.Helper()
	return harness.New(t, func(string) http.Handler { return treeHandler(t) })
}

// TestTheWayBackFromAShellDemoIsATarget: the way back from a shell demo
// is a link in the shell's foot, and it is a target like any other: at
// least --rst-target tall, 32px with a mouse and 44px on a phone. Read
// on every shell demo that has a foot, with a mouse at 1280px and a
// coarse pointer at 390px; a demo whose foot link is not on screen is
// counted, so a selector that stopped matching cannot pass by measuring
// nothing. The link is found by where it goes, the Overview, so a foot
// link left dead at "#" measures nothing and fails.
func TestTheWayBackFromAShellDemoIsATarget(t *testing.T) {
	const read = `(() => [...document.querySelectorAll("[rst-shell-foot] a, [rst-stage-foot] a")]
	  .filter(a => a.getAttribute("href").endsWith("/index.html") && a.checkVisibility())
	  .map(a => ({H: a.getBoundingClientRect().height,
	    Floor: parseFloat(getComputedStyle(document.documentElement).getPropertyValue("--rst-target")) * parseFloat(getComputedStyle(document.documentElement).fontSize)})))()`
	for _, c := range []struct {
		name string
		rig  func(*testing.T) *harness.Rig
		w, h int64
		min  float64
	}{
		{"a mouse at 1280px", mouseRig, 1280, 800, 32},
		{"a coarse pointer at 390px", func(t *testing.T) *harness.Rig { return phoneRig(t) }, 390, 844, 44},
	} {
		rig := c.rig(t)
		ctx, cancel := context.WithTimeout(rig.Context(), 120*time.Second)
		measured := 0
		for _, demo := range layoutDemos(t) {
			where := fmt.Sprintf("%s with %s", demo, c.name)
			var raw string
			if err := chromedp.Run(ctx, chromedp.EmulateViewport(c.w, c.h),
				chromedp.Navigate(rig.Origin+href(demo)),
				chromedp.WaitReady("body"),
				chromedp.Evaluate(`JSON.stringify(`+read+`)`, &raw)); err != nil {
				cancel()
				t.Fatalf("%s: %v", where, err)
			}
			var links []struct{ H, Floor float64 }
			if err := json.Unmarshal([]byte(raw), &links); err != nil {
				cancel()
				t.Fatalf("%s: decoding %s: %v", where, raw, err)
			}
			for _, l := range links {
				measured++
				if l.Floor < c.min {
					t.Errorf("%s: --rst-target is %.0fpx, want at least %.0f", where, l.Floor, c.min)
				}
				if l.H < l.Floor-0.5 {
					t.Errorf("%s: the way back is %.1fpx tall, under the %.0fpx target", where, l.H, l.Floor)
				}
			}
		}
		cancel()
		if measured == 0 {
			t.Errorf("with %s no shell demo showed its way back, so this measured nothing", c.name)
		}
		t.Logf("%s: %d foot links measured", c.name, measured)
	}
}

// TestAShellDemoLaysOutAsAnAppWould: a shell demo is the shell as an
// app gets it, so nothing of the gallery's own styling may move it.
// Rastrillo's demos once linked gallery.css and its bar layout took
// hold of the sidebar demo. Fiesta's frame documents link no gallery
// stylesheet; what they do carry of the gallery's is the frame style
// in their head, whose rules are meant to leave a shell exactly as it
// is. Every element's box is read as served and again with every
// gallery stylesheet and the frame style switched off; the two must
// agree, on every layout document, the column shell included, whose
// body has no wrapper for a markup rule to name and is filled by the
// document mark instead. At 1280 and 900 with a mouse, either side of
// the gallery bar's two-row band, and at 390 with a coarse pointer.
//
// Red first on the column shell, whose body sat in 16px of padding
// before the document mark. Its mutation, run and reverted: dropping
// "> [rst-shell-sidebar]" from the fill rule's :has() list, which gave
// the sidebar demo 1rem of padding and moved every box in it once the
// style was switched off, reported here per element.
func TestAShellDemoLaysOutAsAnAppWould(t *testing.T) {
	const read = `(() => {
	  const boxes = () => [...document.querySelectorAll("body *")].map(e => {
	    const b = e.getBoundingClientRect();
	    return (e.getAttribute("id") || e.tagName.toLowerCase()) + " " + [b.left, b.top, b.width, b.height].map(n => Math.round(n)).join(",");
	  });
	  const served = boxes();
	  const gallery = [...document.styleSheets].filter(s => (s.href && /gallery[^/]*\.css/.test(s.href)) || (!s.href && s.ownerNode && s.ownerNode.tagName === "STYLE"));
	  gallery.forEach(s => { s.disabled = true; });
	  const bare = boxes();
	  gallery.forEach(s => { s.disabled = false; });
	  const diff = [];
	  served.forEach((s, i) => { if (s !== bare[i]) diff.push(s + " (without the gallery's styling: " + bare[i] + ")"); });
	  return JSON.stringify({Main: !!document.querySelector("main"), Sheets: gallery.length, Diff: diff.slice(0, 5)});
	})()`
	for _, c := range []struct {
		name string
		rig  func(*testing.T) *harness.Rig
		w, h int64
	}{
		{"a mouse at 1280px", mouseRig, 1280, 800},
		{"a mouse at 900px", mouseRig, 900, 800},
		{"a coarse pointer at 390px", func(t *testing.T) *harness.Rig { return phoneRig(t) }, 390, 844},
	} {
		rig := c.rig(t)
		ctx, cancel := context.WithTimeout(rig.Context(), 120*time.Second)
		for _, demo := range layoutDemos(t) {
			where := fmt.Sprintf("%s with %s", demo, c.name)
			var raw string
			if err := chromedp.Run(ctx, chromedp.EmulateViewport(c.w, c.h),
				chromedp.Navigate(rig.Origin+href(demo)),
				chromedp.WaitReady("body"),
				chromedp.Evaluate(read, &raw)); err != nil {
				cancel()
				t.Fatalf("%s: %v", where, err)
			}
			var got struct {
				Main   bool
				Sheets int
				Diff   []string
			}
			if err := json.Unmarshal([]byte(raw), &got); err != nil {
				cancel()
				t.Fatalf("%s: decoding %s: %v", where, raw, err)
			}
			if !got.Main {
				t.Errorf("%s: no main element; the demo is not the page this test knows", where)
			}
			if got.Sheets == 0 {
				t.Errorf("%s: no gallery styling was switched off, so the two readings are the same reading", where)
			}
			for _, d := range got.Diff {
				t.Errorf("%s: the gallery's styling moves %s", where, d)
			}
		}
		cancel()
		t.Logf("%s: %d demos read with the frame style switched off", c.name, len(layoutDemos(t)))
	}
}