package main

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/xml"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"testing"
)

func newTestServer(t *testing.T, files map[string]string) (*httptest.Server, string) {
	t.Helper()
	dir := t.TempDir()
	for name, src := range files {
		writeFile(t, dir, name, src)
	}
	a, err := newApp(dir, "https://posts.example.com/")
	if err != nil {
		t.Fatal(err)
	}
	srv := httptest.NewServer(a.routes())
	t.Cleanup(srv.Close)
	return srv, dir
}

func writeFile(t *testing.T, dir, name, src string) {
	t.Helper()
	if err := os.WriteFile(filepath.Join(dir, name), []byte(src), 0o644); err != nil {
		t.Fatal(err)
	}
}

func get(t *testing.T, srv *httptest.Server, path string) (int, http.Header, string) {
	t.Helper()
	resp, err := http.Get(srv.URL + path)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		t.Fatal(err)
	}
	return resp.StatusCode, resp.Header, string(body)
}

var sample = map[string]string{
	"2026-01-01-oldest.md": "# Oldest\n",
	"2026-02-01-middle.md": "---\ntitle: Middle\nsummary: The middle one.\n---\nMiddle body\n",
	"2026-03-01-newest.md": "# Newest\n",
	"2026-04-01-draft.md":  "---\ndraft: true\n---\n# Secret draft\n",
	"Bad Name.md":          "# Broken\n",
	"notes.txt":            "not a post",
}

func TestIndex(t *testing.T) {
	srv, _ := newTestServer(t, sample)
	status, h, body := get(t, srv, "/")
	if status != 200 {
		t.Fatalf("status = %d", status)
	}
	if h.Get("Content-Security-Policy") == "" || h.Get("X-Content-Type-Options") != "nosniff" {
		t.Errorf("missing security headers: %v", h)
	}
	n, m, o := strings.Index(body, "Newest"), strings.Index(body, "Middle"), strings.Index(body, "Oldest")
	if n < 0 || m < 0 || o < 0 || !(n < m && m < o) {
		t.Errorf("posts missing or out of order:\n%s", body)
	}
	if !strings.Contains(body, "The middle one.") {
		t.Error("summary not shown")
	}
	for _, hidden := range []string{"Secret draft", "Broken"} {
		if strings.Contains(body, hidden) {
			t.Errorf("%q should not be listed", hidden)
		}
	}
}

func TestEmptyIndex(t *testing.T) {
	srv, _ := newTestServer(t, nil)
	if status, _, body := get(t, srv, "/"); status != 200 || !strings.Contains(body, "No posts yet") {
		t.Errorf("status = %d, body:\n%s", status, body)
	}
}

func TestPostPage(t *testing.T) {
	srv, _ := newTestServer(t, sample)
	status, _, body := get(t, srv, "/posts/middle")
	if status != 200 {
		t.Fatalf("status = %d", status)
	}
	for _, want := range []string{
		"<title>Middle · posts.example.com</title>",
		"<p>Middle body</p>",
		`<a class="newer" href="/posts/newest">`,
		`<a class="older" href="/posts/oldest">`,
	} {
		if !strings.Contains(body, want) {
			t.Errorf("missing %q in:\n%s", want, body)
		}
	}

	_, _, newest := get(t, srv, "/posts/newest")
	if strings.Contains(newest, `class="newer"`) {
		t.Error("newest post should have no newer link")
	}
	_, _, oldest := get(t, srv, "/posts/oldest")
	if strings.Contains(oldest, `class="older"`) {
		t.Error("oldest post should have no older link")
	}
}

func TestNotFound(t *testing.T) {
	srv, _ := newTestServer(t, sample)
	for _, path := range []string{
		"/posts/nope",
		"/posts/draft",
		"/posts/2026-01-01-oldest",
		"/posts/..%2f..%2fetc%2fpasswd",
		"/posts/",
		"/static/",
		"/static/missing.css",
		"/whatever",
	} {
		status, _, body := get(t, srv, path)
		if status != 404 {
			t.Errorf("%s: status = %d, want 404", path, status)
		}
		if path != "/static/missing.css" && !strings.Contains(body, "<h1>404</h1>") {
			t.Errorf("%s: expected styled 404 page", path)
		}
	}
}

func TestStatic(t *testing.T) {
	srv, _ := newTestServer(t, nil)
	status, h, body := get(t, srv, "/static/style.css")
	if status != 200 || !strings.HasPrefix(h.Get("Content-Type"), "text/css") || !strings.Contains(body, ":root") {
		t.Errorf("status = %d, type = %q", status, h.Get("Content-Type"))
	}
}

func TestStylesheetCacheBusting(t *testing.T) {
	srv, _ := newTestServer(t, nil)
	_, _, page := get(t, srv, "/")
	m := regexp.MustCompile(`<link rel="stylesheet" href="(/static/style\.css\?v=([0-9a-f]{10}))">`).FindStringSubmatch(page)
	if m == nil {
		t.Fatalf("no hashed stylesheet link in:\n%s", page)
	}
	b, err := staticFS.ReadFile("static/style.css")
	if err != nil {
		t.Fatal(err)
	}
	sum := sha256.Sum256(b)
	if want := hex.EncodeToString(sum[:])[:10]; m[2] != want {
		t.Errorf("hash = %s, want %s", m[2], want)
	}

	for path, want := range map[string]string{
		m[1]:                             "public, max-age=31536000, immutable",
		"/static/style.css":              "public, max-age=3600",
		"/static/style.css?v=0000000000": "public, max-age=3600",
	} {
		status, h, _ := get(t, srv, path)
		if status != 200 || h.Get("Cache-Control") != want {
			t.Errorf("%s: status = %d, Cache-Control = %q, want %q", path, status, h.Get("Cache-Control"), want)
		}
	}
}

func TestFeed(t *testing.T) {
	srv, _ := newTestServer(t, sample)
	status, h, body := get(t, srv, "/feed.xml")
	if status != 200 || !strings.HasPrefix(h.Get("Content-Type"), "application/rss+xml") {
		t.Fatalf("status = %d, type = %q", status, h.Get("Content-Type"))
	}
	var feed rss
	if err := xml.Unmarshal([]byte(body), &feed); err != nil {
		t.Fatalf("invalid XML: %v\n%s", err, body)
	}
	items := feed.Channel.Items
	if len(items) != 3 {
		t.Fatalf("got %d items, want 3", len(items))
	}
	if items[0].Link != "https://posts.example.com/posts/newest" {
		t.Errorf("first link = %q", items[0].Link)
	}
	if items[1].Description != "The middle one." {
		t.Errorf("description = %q", items[1].Description)
	}
}

func TestHeaderAndFooter(t *testing.T) {
	srv, dir := newTestServer(t, sample)
	for _, path := range []string{"/", "/posts/middle", "/about", "/nope"} {
		_, _, body := get(t, srv, path)
		for _, want := range []string{
			`<a class="home" href="/">Home</a>`,
			`<nav><a href="/about">About</a></nav>`,
			"<footer class=\"site\">\n  <a href=\"/feed.xml\">RSS</a>\n</footer>",
		} {
			if !strings.Contains(body, want) {
				t.Errorf("%s: missing %q", path, want)
			}
		}
	}

	writeFile(t, dir, "site.json", `{"homeText": "All <posts>"}`)
	if _, _, body := get(t, srv, "/"); !strings.Contains(body, `<a class="home" href="/">All &lt;posts&gt;</a>`) {
		t.Errorf("configured home text not used (or not escaped):\n%s", body)
	}
	if status, _, _ := get(t, srv, "/posts/site"); status != 404 {
		t.Error("site.json should not be treated as a post")
	}
}

func TestAboutPage(t *testing.T) {
	srv, _ := newTestServer(t, sample)
	status, _, body := get(t, srv, "/about")
	if status != 200 {
		t.Fatalf("status = %d", status)
	}
	for _, want := range []string{
		"<title>About · posts.example.com</title>",
		"<dt>Version</dt>\n    <dd>" + version,
		"<dt>Posts</dt>\n    <dd>3</dd>",
		`<dd><a href="/posts/newest">Newest</a>`,
		`<h2 id="the-header-block">The header block</h2>`,
		`<h2 id="what-markdown-works">What Markdown works</h2>`,
	} {
		if !strings.Contains(body, want) {
			t.Errorf("missing %q in:\n%s", want, body)
		}
	}

	empty, _ := newTestServer(t, nil)
	_, _, body = get(t, empty, "/about")
	if !strings.Contains(body, "<dd>0</dd>") || strings.Contains(body, "Latest post") {
		t.Errorf("empty site: expected 0 posts and no latest post:\n%s", body)
	}
}

func TestReloadsWhenContentChanges(t *testing.T) {
	srv, dir := newTestServer(t, map[string]string{"2026-01-01-one.md": "# One\n"})
	if _, _, body := get(t, srv, "/"); strings.Contains(body, "Two") {
		t.Fatal("unexpected post")
	}
	writeFile(t, dir, "2026-01-02-two.md", "# Two\n")
	if status, _, _ := get(t, srv, "/posts/two"); status != 200 {
		t.Errorf("new post not picked up: status = %d", status)
	}
	if err := os.Remove(filepath.Join(dir, "2026-01-01-one.md")); err != nil {
		t.Fatal(err)
	}
	if status, _, _ := get(t, srv, "/posts/one"); status != 404 {
		t.Errorf("removed post still served: status = %d", status)
	}
}