package web

import (
	"bytes"
	"html/template"
	"strings"
	"testing"

	"gitea.dooplex.hu/admin/felhom-controller/internal/system"
)

// R-259 — a disk we could not measure must not be drawn as a healthy empty one.
//
// These render the REAL dashboard template block against a real SystemInfo, because the defect was
// entirely in what the markup does with a zero. A test on the Go struct alone cannot see it.

// diskMeterBlock EXTRACTS the system-disk block from the SHIPPED dashboard.html, rather than
// duplicating it here. A copied block drifts, and a drifted copy is a test that passes while the
// page it claims to cover has changed — the fixture-is-not-the-wire mistake, which this project has
// now hit twice (R-262, and the OOB fixture in hub v0.99.0).
func diskMeterBlock(t *testing.T) string {
	t.Helper()
	raw, err := templateFS.ReadFile("templates/dashboard.html")
	if err != nil {
		t.Fatalf("read dashboard.html: %v", err)
	}
	src := string(raw)
	const startMark = `{{if not .SystemInfo.DiskKnown}}`
	i := strings.Index(src, startMark)
	if i < 0 {
		t.Fatalf("the DiskKnown guard is not in dashboard.html — R-259's fix is not in the shipped markup")
	}
	// the guard's matching {{end}} is the one closing the if/else chain: take through the
	// "Kritikusan kevés hely" branch and its two closers
	const endMark = `Kritikusan kevés hely</div>{{end}}`
	j := strings.Index(src[i:], endMark)
	if j < 0 {
		t.Fatal("could not find the end of the disk meter block")
	}
	block := src[i : i+j+len(endMark)]
	// close the outer if/else opened by startMark
	return block + "\n        </div>\n        {{end}}"
}

// renderDiskMeter renders just the system-disk block of dashboard.html with the production funcmap.
func renderDiskMeter(t *testing.T, info system.SystemInfo) string {
	t.Helper()
	// the block under test, copied verbatim from dashboard.html by the guard below
	src := diskMeterBlock(t)
	tpl, err := template.New("m").Funcs((&Server{}).templateFuncMap()).Parse(src)
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	var buf bytes.Buffer
	if err := tpl.Execute(&buf, map[string]any{"SystemInfo": info}); err != nil {
		t.Fatalf("execute: %v", err)
	}
	return buf.String()
}

func healthyDisk() system.SystemInfo {
	return system.SystemInfo{
		DiskTotalGB: 100, DiskUsedGB: 42, DiskAvailGB: 58, DiskPercent: 42, DiskKnown: true,
	}
}

// SCENARIO D — a disk we could not read says so, and draws nothing.
func TestDiskMeter_UnknownDrawsNoPictureAndSaysSo(t *testing.T) {
	// exactly what a failed statfs leaves behind: every figure zero, and now DiskKnown=false
	out := renderDiskMeter(t, system.SystemInfo{DiskKnown: false})

	if strings.Contains(out, "0.0 GB") || strings.Contains(out, "(0%)") {
		t.Errorf("a failed measurement printed a figure — „0.0 GB / 0.0 GB (0%%)\" is R-259, "+
			"and it is the healthy-looking picture of an unread disk.\n%s", out)
	}
	if strings.Contains(out, "meter-fill") {
		t.Errorf("a meter fill was drawn for a disk that was never measured — a 0%%-wide bar over an "+
			"unread store is a picture of emptiness, and a picture is a claim.\n%s", out)
	}
	if strings.Contains(out, "nominal") {
		t.Errorf("an unmeasured disk was coloured as healthy.\n%s", out)
	}
	if !strings.Contains(out, "nem olvashat") { // ASCII-safe fragment of „nem olvasható ki"
		t.Errorf("the customer is not told the measurement could not be taken.\n%s", out)
	}
}

// SCENARIO E — a disk we CAN read is unchanged, including its colour band.
func TestDiskMeter_KnownIsUnchanged(t *testing.T) {
	out := renderDiskMeter(t, healthyDisk())

	// fmtGB: >=100 renders whole, >=10 renders one decimal (funcmap.go:208-215)
	for _, want := range []string{"42.0 GB", "100 GB", "(42%)", "meter-fill", "nominal"} {
		if !strings.Contains(out, want) {
			t.Errorf("a healthy box lost %q from its meter — this change must be invisible on a "+
				"machine that is fine.\n%s", want, out)
		}
	}
	if strings.Contains(out, "nem olvashat") {
		t.Errorf("a healthy box gained the could-not-measure caveat.\n%s", out)
	}
}

// The colour bands still work on a known disk — the guard must not have swallowed them.
func TestDiskMeter_KnownStillBands(t *testing.T) {
	crit := healthyDisk()
	crit.DiskPercent = 92
	out := renderDiskMeter(t, crit)
	if !strings.Contains(out, "crit") || !strings.Contains(out, "Kritikusan") {
		t.Errorf("a critically full KNOWN disk lost its warning.\n%s", out)
	}
}