package templates_test

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

	"git.eeqj.de/sneak/routewatch/internal/database"
	"git.eeqj.de/sneak/routewatch/internal/templates"
)

// renderPage renders a page with the data every page needs, and the visitor's
// address, which the home page also needs.
func renderPage(t *testing.T, tmpl *template.Template) string {
	t.Helper()

	var page bytes.Buffer

	err := tmpl.Execute(&page, struct{ CSPNonce, ClientIP string }{})
	if err != nil {
		t.Fatalf("rendering the page: %v", err)
	}

	return page.String()
}

// TestFooterLicense renders the home and status pages and expects each footer
// to name the licence in LICENSE, MIT, and not WTFPL.
func TestFooterLicense(t *testing.T) {
	t.Parallel()

	const (
		license      = "MIT"
		wrongLicense = "WTFPL"
	)

	pages := map[string]*template.Template{
		"index":  templates.IndexTemplate(),
		"status": templates.StatusTemplate(),
	}

	for name, tmpl := range pages {
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			_, footer, found := strings.Cut(renderPage(t, tmpl), "<footer")
			if !found {
				t.Fatal("the page has no footer")
			}

			footer, _, _ = strings.Cut(footer, "</footer>")

			if !strings.Contains(footer, license) {
				t.Errorf("footer does not name %s: %q", license, footer)
			}

			if strings.Contains(footer, wrongLicense) {
				t.Errorf("footer names %s: %q", wrongLicense, footer)
			}
		})
	}
}

// TestFreshnessIndicator renders the home and status pages and expects each to
// have, right after the status element, the element where the page's script
// shows its spinner or "stale".
func TestFreshnessIndicator(t *testing.T) {
	t.Parallel()

	pages := map[string]struct {
		tmpl      *template.Template
		status    string
		indicator string
	}{
		"index": {
			tmpl:      templates.IndexTemplate(),
			status:    `<span id="stat-status">-</span>`,
			indicator: `<span id="freshness"></span>`,
		},
		"status": {
			tmpl:      templates.StatusTemplate(),
			status:    `<span class="metric-value" id="connected">-</span>`,
			indicator: `<span class="metric-value" id="freshness"></span>`,
		},
	}

	for name, page := range pages {
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			_, afterStatus, found := strings.Cut(renderPage(t, page.tmpl), page.status)
			if !found {
				t.Fatalf("the page has no status element %s", page.status)
			}

			if !strings.HasPrefix(strings.TrimSpace(afterStatus), page.indicator) {
				t.Errorf("the status element is not followed by %s", page.indicator)
			}
		})
	}
}

// TestASDetailPrefixListsFold renders the AS page with one IPv4 and one IPv6
// prefix. It expects each prefix list inside its own <details> element that
// starts open and whose <summary> holds the list's heading, so that a click on
// the heading folds the list.
func TestASDetailPrefixListsFold(t *testing.T) {
	t.Parallel()

	const (
		asn      = 64500
		prefixV4 = "192.0.2.0/24"
		prefixV6 = "2001:db8::/32"
	)

	ipv4 := []database.LiveRoute{{Prefix: prefixV4}}
	ipv6 := []database.LiveRoute{{Prefix: prefixV6}}

	// The fields the AS page handler gives the template.
	data := struct {
		ASN          *database.ASN
		IPv4Prefixes []database.LiveRoute
		IPv6Prefixes []database.LiveRoute
		TotalCount   int
		IPv4Count    int
		IPv6Count    int
		Peers        []database.ASPeer
		PeerCount    int
		CSPNonce     string
	}{
		ASN:          &database.ASN{ASN: asn},
		IPv4Prefixes: ipv4,
		IPv6Prefixes: ipv6,
		TotalCount:   len(ipv4) + len(ipv6),
		IPv4Count:    len(ipv4),
		IPv6Count:    len(ipv6),
	}

	var rendered bytes.Buffer

	err := templates.ASDetailTemplate().Execute(&rendered, data)
	if err != nil {
		t.Fatalf("rendering the page: %v", err)
	}

	page := rendered.String()

	lists := []struct{ heading, prefix string }{
		{"IPv4 Prefixes", prefixV4},
		{"IPv6 Prefixes", prefixV6},
	}

	for _, list := range lists {
		before, _, found := strings.Cut(page, list.prefix)
		if !found {
			t.Fatalf("the page does not list %s", list.prefix)
		}

		// The list's section starts at the last <details before its prefix.
		start := strings.LastIndex(before, "<details")
		if start < 0 || strings.Contains(before[start:], "</details>") {
			t.Errorf("%s: the list is not inside a <details> element", list.heading)

			continue
		}

		tag, section, _ := strings.Cut(before[start:], ">")
		if !strings.Contains(tag, " open") {
			t.Errorf("%s: the <details> element does not start open: %s>",
				list.heading, tag)
		}

		_, summary, _ := strings.Cut(section, "<summary")
		summary, _, _ = strings.Cut(summary, "</summary>")

		if !strings.Contains(summary, list.heading) {
			t.Errorf("%s: the <summary> does not hold the heading", list.heading)
		}
	}
}