package docsite

import (
	"bytes"
	"context"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"
	"testing"
	"time"
)

// themeTree is a two-section fixture: the index (two H2 headings, a
// callout), two setup pages and one API page with a Go fence.
func themeTree(t *testing.T) string {
	t.Helper()
	return writeTree(t, map[string]string{
		"docs/site.yaml": fixtureSite + "edit_url: \"https://forge.example/edit/{path}\"\n",
		"docs/index.md": page("Acme docs", "index", 0,
			"## Alpha\n\nText.\n\n### Detail\n\n> [!NOTE]\n> A note.\n\n> [!TIP]\n> A tip.\n\n> [!WARNING]\n> Careful.\n\n"+
				"```sh\n$ summer docs:build\n```\n\n## Beta\n\nMore.\n"),
		"docs/setup/start.md":    page("Start", "setup", 10, "## Only heading\n\nText.\n"),
		"docs/setup/second.md":   page("Second", "setup", 20, "Text.\n"),
		"modules/alpha/alpha.go": "package alpha\n",
		"modules/alpha/README.md": "# alpha\n\nAlpha does one thing well.\n\n## Usage\n\n" +
			"```go\nfunc main() {\n\treturn \"x\" // done\n}\n```\n\n```yaml\nkey: true\n```\n",
	})
}

func buildTheme(t *testing.T) string {
	t.Helper()
	out := filepath.Join(t.TempDir(), "site")
	if _, problems, err := Build(Options{Root: themeTree(t), Commands: fixtureCommands, Out: out}); err != nil || len(problems) > 0 {
		t.Fatalf("Build: %v %q", err, problemLines(problems))
	}
	return out
}

func readOut(t *testing.T, out, name string) string {
	t.Helper()
	b, err := os.ReadFile(filepath.Join(out, name))
	if err != nil {
		t.Fatal(err)
	}
	return string(b)
}

var (
	scriptTag   = regexp.MustCompile(`<script[^>]*>`)
	anyTag      = regexp.MustCompile(`<[a-zA-Z][^>]*>`)
	styleAttr   = regexp.MustCompile(`\sstyle=`)
	handlerAttr = regexp.MustCompile(`\son[a-z]+=`)
)

// assertCSPSafe fails on inline script bodies, inline styles and inline
// event handlers (script-src 'self'; style-src 'self').
func assertCSPSafe(t *testing.T, name, html string) {
	t.Helper()
	for _, loc := range scriptTag.FindAllStringIndex(html, -1) {
		tag := html[loc[0]:loc[1]]
		if !strings.Contains(tag, ` src="`) || !strings.HasPrefix(html[loc[1]:], "</script>") {
			t.Errorf("%s has an inline script: %s", name, tag)
		}
	}
	for _, tag := range anyTag.FindAllString(html, -1) {
		if styleAttr.MatchString(tag) || handlerAttr.MatchString(tag) {
			t.Errorf("%s has an inline style or handler: %s", name, tag)
		}
	}
	if strings.Contains(html, "<style") {
		t.Errorf("%s has a <style> element", name)
	}
}

func TestBuildSiteMarkers(t *testing.T) {
	out := buildTheme(t)
	index := readOut(t, out, "index.html")
	for _, marker := range []string{
		`<body class="docs">`,
		`<header class="site-header">`,
		`<nav class="sidebar" aria-label="Documentation">`,
		`<aside class="toc" aria-label="On this page">`,
		`<details class="toc-inline">`,
		`<div class="page-actions">`,
		`<nav class="pager" aria-label="Previous and next page">`,
		`<footer class="site-footer">`,
		`<dialog class="search" id="search">`,
		`<button class="theme-toggle"`,
		`<figure class="code">`,
		`<aside class="callout callout-note" role="note">`,
		`<aside class="callout callout-tip" role="note">`,
		`<aside class="callout callout-warning" role="note">`,
		`<a class="heading-anchor" href="#alpha" aria-label="Link to section: Alpha">#</a>`,
		`<svg class="icon icon-`,
		`<link rel="stylesheet" href="/assets/site.css">`,
		`<script src="/assets/theme-init.js"></script>`,
		`<meta name="color-scheme" content="light dark">`,
		`<meta property="og:title" content="Acme docs">`,
		`<link rel="alternate" type="text/markdown" href="/index.md">`,
		`href="https://forge.example/edit/docs/index.md"`,
		`View as Markdown`,
		`aria-label="SummerCMS documentation home"`,
		`aria-controls="sidebar"`,
		`<span class="tok-prompt">$ </span><span class="tok-kw">summer</span>`,
		`href="/llms.txt"`,
		`href="/llms-full.txt"`,
		`class="toc-h3"`,
	} {
		if !strings.Contains(index, marker) {
			t.Errorf("index.html missing %s", marker)
		}
	}
	if strings.Contains(index, "[!NOTE]") {
		t.Error("callout marker line rendered")
	}
	if i, j := strings.Index(index, "theme-init.js"), strings.Index(index, "site.css"); i < 0 || j < 0 || i > j {
		t.Error("theme-init.js must load before the stylesheet")
	}

	// First page: Next only (the empty Previous cell keeps Next on the right).
	if !strings.Contains(index, `<span class="pager-empty"></span>`) || strings.Contains(index, "pager-prev") || !strings.Contains(index, "pager-next") {
		t.Error("index.html pager should hold Next only")
	}
	// One H2 and no H3: no TOC; the pager crosses into the API section.
	start := readOut(t, out, "setup/start.html")
	if strings.Contains(start, `class="toc"`) || strings.Contains(start, "toc-inline") {
		t.Error("setup/start.html has a TOC with one heading")
	}
	if !strings.Contains(start, `<p class="eyebrow">Setup</p>`) {
		t.Error("setup/start.html has no section eyebrow")
	}
	second := readOut(t, out, "setup/second.html")
	if !strings.Contains(second, `<span class="pager-section">API reference</span>`) {
		t.Error("cross-section Next has no section line")
	}
	if strings.Count(second, `class="pager-section"`) != 1 {
		t.Error("same-section Previous must not carry a section line")
	}
	// Last page: Previous only.
	api := readOut(t, out, "api/alpha.html")
	if !strings.Contains(api, "pager-prev") || strings.Contains(api, "pager-next") {
		t.Error("api/alpha.html pager should hold Previous only")
	}
	for _, want := range []string{
		`<span class="tok-kw">func</span>`,
		`<span class="tok-str">&#34;x&#34;</span>`,
		`<span class="tok-com">// done</span>`,
		`<span class="tok-key">key</span>`,
		`<span class="tok-num">true</span>`,
		`<code class="language-go">`,
		`<button type="button" class="copy-button" aria-label="Copy code" hidden>`,
		`<div class="sidebar-section sidebar-api">`,
		`aria-current="page"`,
	} {
		if !strings.Contains(api, want) {
			t.Errorf("api/alpha.html missing %s", want)
		}
	}

	notFound := readOut(t, out, "404.html")
	for _, want := range []string{`<body class="docs docs-404">`, "<h1>Page not found</h1>", "This page does not exist or has moved.", `>documentation home</a>`} {
		if !strings.Contains(notFound, want) {
			t.Errorf("404.html missing %s", want)
		}
	}
	for _, not := range []string{`aria-current="page"`, `class="toc"`, `class="pager"`, "page-actions"} {
		if strings.Contains(notFound, not) {
			t.Errorf("404.html must not contain %s", not)
		}
	}

	for _, name := range []string{"index.html", "setup/start.html", "setup/second.html", "api/alpha.html", "404.html"} {
		html := readOut(t, out, name)
		assertCSPSafe(t, name, html)
		if strings.Contains(html, "//fonts.") || strings.Contains(html, "cdn") {
			t.Errorf("%s references a third-party asset origin", name)
		}
	}
	for _, name := range []string{"assets/site.js", "assets/search.js", "assets/theme-init.js", "assets/fonts/dm-mono-latin-400-normal.woff2"} {
		if _, err := os.Stat(filepath.Join(out, name)); err != nil {
			t.Errorf("missing %s", name)
		}
	}

	// A one-page site renders no pager.
	var buf bytes.Buffer
	if err := pageTmpl.ExecuteTemplate(&buf, "pager", pageView{}); err != nil {
		t.Fatal(err)
	}
	if strings.TrimSpace(buf.String()) != "" {
		t.Errorf("pager without prev/next = %q, want nothing", buf.String())
	}
}

func TestServeHandler(t *testing.T) {
	srv := httptest.NewServer(Handler(buildTheme(t)))
	defer srv.Close()
	get := func(p string) (int, string) {
		t.Helper()
		res, err := http.Get(srv.URL + p)
		if err != nil {
			t.Fatal(err)
		}
		defer res.Body.Close()
		body, _ := io.ReadAll(res.Body)
		return res.StatusCode, string(body)
	}
	for _, p := range []string{"/index.html", "/", "/setup/start.html", "/assets/site.css", "/search-index.json"} {
		if code, _ := get(p); code != http.StatusOK {
			t.Errorf("GET %s = %d, want 200", p, code)
		}
	}
	for _, p := range []string{"/missing.html", "/setup/", "/.summer-docs", "/assets/../.summer-docs", "/%2e%2e/etc/passwd"} {
		code, body := get(p)
		if code != http.StatusNotFound || !strings.Contains(body, "Page not found") {
			t.Errorf("GET %s = %d, want 404 with the Page not found body", p, code)
		}
	}
}

// syncBuffer is a goroutine-safe bytes.Buffer.
type syncBuffer struct {
	mu  sync.Mutex
	buf bytes.Buffer
}

func (b *syncBuffer) Write(p []byte) (int, error) {
	b.mu.Lock()
	defer b.mu.Unlock()
	return b.buf.Write(p)
}

func (b *syncBuffer) String() string {
	b.mu.Lock()
	defer b.mu.Unlock()
	return b.buf.String()
}

var servingLine = regexp.MustCompile(`Serving docs at (http://\S+) \(press Ctrl\+C to stop\)`)

func TestServeRefusesNonLoopback(t *testing.T) {
	opts := Options{Root: themeTree(t), Commands: fixtureCommands}
	for _, addr := range []string{"0.0.0.0:8088", "192.0.2.1:8088", "example.com:8088", ":8088"} {
		var out bytes.Buffer
		err := Serve(context.Background(), opts, addr, false, &out)
		want := "docs:serve: refusing to listen on " + addr + ": not a loopback address. Pass --allow-remote to serve on the network."
		if err == nil || err.Error() != want {
			t.Errorf("Serve(%s) = %v, want %q", addr, err, want)
		}
	}
	if err := checkServeAddr("0.0.0.0:0", true); err != nil {
		t.Errorf("--allow-remote still refused: %v", err)
	}

	for _, addr := range []string{"127.0.0.1:0", "localhost:0"} {
		ctx, cancel := context.WithCancel(context.Background())
		out := &syncBuffer{}
		done := make(chan error, 1)
		go func() { done <- Serve(ctx, opts, addr, false, out) }()
		var base string
		for deadline := time.Now().Add(20 * time.Second); time.Now().Before(deadline); time.Sleep(20 * time.Millisecond) {
			if m := servingLine.FindStringSubmatch(out.String()); m != nil {
				base = m[1]
				break
			}
		}
		if base == "" {
			cancel()
			t.Fatalf("Serve(%s) printed no serving line: %s", addr, out.String())
		}
		res, err := http.Get(base + "/index.html")
		if err != nil {
			cancel()
			t.Fatal(err)
		}
		res.Body.Close()
		if res.StatusCode != http.StatusOK {
			t.Errorf("Serve(%s) GET /index.html = %d", addr, res.StatusCode)
		}
		cancel()
		select {
		case err := <-done:
			if err != nil {
				t.Errorf("Serve(%s) = %v after cancel", addr, err)
			}
		case <-time.After(10 * time.Second):
			t.Fatalf("Serve(%s) did not return after cancel", addr)
		}
	}
}