// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0

package feeds

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"sourcedock.dev/petrbalvin/volumen/internal/config"
	"sourcedock.dev/petrbalvin/volumen/internal/frontmatter"
	"sourcedock.dev/petrbalvin/volumen/internal/post"
)

var testSite = config.Site{
	Title:       "Můj blog",
	Description: "Testovací blog",
	BaseURL:     "https://site.example",
	Language:    "cs",
	Author:      "Petr",
}

func samplePosts(t *testing.T) []*post.Post {
	t.Helper()
	p1 := parsePost(t, "+++\ntitle = \"První & <pos>\"\nslug = \"prvni\"\ndate = 2026-08-18\nlang = \"cs\"\ntags = [\"go\"]\nfediverse_creator = \"@petr@social\"\n+++\nTělo **jedna**.\n")
	p2 := parsePost(t, "+++\ntitle = \"Druhý\"\nslug = \"druhy\"\n+++\nTělo dva.\n")
	p1.Path = filepath.Join(t.TempDir(), "prvni.md")
	return []*post.Post{p1, p2}
}

func parsePost(t *testing.T, content string) *post.Post {
	t.Helper()
	p, err := post.Parse(content)
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	return p
}

func TestRenderRSSFeed(t *testing.T) {
	posts := samplePosts(t)
	out := RenderRSSFeed(posts, testSite, "https://site.example", "/api/volumen/feed.xml")
	for _, want := range []string{
		`<?xml version="1.0" encoding="UTF-8"?>`,
		`<rss version="2.0"`,
		`<title>Můj blog</title>`,
		`<title>První &amp; &lt;pos&gt;</title>`,
		`<link>https://site.example/prvni</link>`,
		`<guid>https://site.example/prvni</guid>`,
		`<pubDate>Tue, 18 Aug 2026 00:00:00 GMT</pubDate>`,
		`<dc:creator>@petr@social</dc:creator>`,
		`<dc:language>cs</dc:language>`,
		`<language>cs</language>`,
	} {
		if !strings.Contains(out, want) {
			t.Fatalf("rss missing %q:\n%s", want, out)
		}
	}
	// Post without a date has no pubDate.
	if strings.Contains(out, "druhý</title>") && strings.Count(out, "<pubDate>") != 1 {
		t.Fatalf("unexpected pubDate count:\n%s", out)
	}
}

func TestRenderRSSFeedItemLimit(t *testing.T) {
	var posts []*post.Post
	for range FeedItemLimit + 5 {
		p := parsePost(t, "+++\nslug = \"p\"\ntitle = \"t\"\n+++\nx\n")
		posts = append(posts, p)
	}
	out := RenderRSSFeed(posts, testSite, "https://site.example", "/api/volumen/feed.xml")
	if got := strings.Count(out, "<item>"); got != FeedItemLimit {
		t.Fatalf("items = %d, want %d", got, FeedItemLimit)
	}
}

func TestRenderAtomFeed(t *testing.T) {
	posts := samplePosts(t)
	out := RenderAtomFeed(posts, testSite, "https://site.example", "/api/volumen/feed.atom")
	for _, want := range []string{
		`<feed xmlns="http://www.w3.org/2005/Atom">`,
		`<link rel="self" type="application/atom+xml" href="https://site.example/api/volumen/feed.atom"/>`,
		`<id>https://site.example/</id>`,
		`<updated>2026-08-18T00:00:00+00:00</updated>`,
		`<title xml:lang="cs">První &amp; &lt;pos&gt;</title>`,
		`<published>2026-08-18T00:00:00+00:00</published>`,
		`<author><name>@petr@social</name></author>`,
		`<summary>Tělo jedna.</summary>`,
	} {
		if !strings.Contains(out, want) {
			t.Fatalf("atom missing %q:\n%s", want, out)
		}
	}
}

func TestRenderAtomFeedWithoutDates(t *testing.T) {
	p := parsePost(t, "+++\nslug = \"x\"\ntitle = \"X\"\n+++\nb\n")
	out := RenderAtomFeed([]*post.Post{p}, testSite, "https://site.example", "/api/volumen/feed.atom")
	// An entry without a date emits empty updated and published
	// elements, which consumers rely on.
	if !strings.Contains(out, "<updated></updated>") {
		t.Fatalf("empty updated element missing:\n%s", out)
	}
	if !strings.Contains(out, "<published></published>") {
		t.Fatalf("empty published element missing:\n%s", out)
	}
}

func TestRenderJSONFeed(t *testing.T) {
	posts := samplePosts(t)
	out := RenderJSONFeed(posts, testSite, "https://site.example", "/api/volumen/feed.json")
	if out.Version != "https://jsonfeed.org/version/1.1" {
		t.Fatalf("version = %v", out.Version)
	}
	if out.Title != "Můj blog" || out.Language != "cs" {
		t.Fatalf("feed = %+v", out)
	}
	if out.FeedURL != "https://site.example/api/volumen/feed.json" {
		t.Fatalf("feed_url = %v", out.FeedURL)
	}
	if len(out.Items) != 2 {
		t.Fatalf("items = %v", out.Items)
	}
	first := out.Items[0]
	if first.ID != "https://site.example/prvni" {
		t.Fatalf("item = %+v", first)
	}
	if !strings.Contains(first.ContentHTML, "<strong>jedna</strong>") {
		t.Fatalf("content_html = %v", first.ContentHTML)
	}
	if first.DatePublished != "2026-08-18" {
		t.Fatalf("date_published = %v", first.DatePublished)
	}
	if len(first.Authors) != 1 || first.Authors[0].Name != "@petr@social" {
		t.Fatalf("authors = %v", first.Authors)
	}
	if second := out.Items[1]; second.DatePublished != "" {
		t.Fatalf("date_published should be empty: %+v", second)
	}
}

func TestRenderJSONFeedSiteAuthorFallback(t *testing.T) {
	p := parsePost(t, "+++\nslug = \"x\"\ntitle = \"X\"\n+++\nb\n")
	site := config.Site{Title: "T", FediverseCreator: "@site@host"}
	out := RenderJSONFeed([]*post.Post{p}, site, "https://site.example", "/api/volumen/feed.json")
	if len(out.Items) != 1 || out.Items[0].Authors[0].Name != "@site@host" {
		t.Fatalf("authors = %v", out.Items)
	}
}

func TestRenderSitemap(t *testing.T) {
	posts := samplePosts(t)
	out := RenderSitemap(posts, "https://site.example")
	for _, want := range []string{
		`<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">`,
		`<loc>https://site.example/prvni</loc>`,
		`<lastmod>`,
		`<loc>https://site.example/druhy</loc>`,
	} {
		if !strings.Contains(out, want) {
			t.Fatalf("sitemap missing %q:\n%s", want, out)
		}
	}
}

func TestSitemapLastmodFallsBackToDate(t *testing.T) {
	p := parsePost(t, "+++\nslug = \"x\"\ndate = 2026-01-02\n+++\nb\n")
	out := RenderSitemap([]*post.Post{p}, "https://site.example")
	if !strings.Contains(out, "<lastmod>2026-01-02</lastmod>") {
		t.Fatalf("sitemap = %s", out)
	}
}

func TestUnparseableDatePassesThrough(t *testing.T) {
	if got := rfc822Date("not-a-date"); got != "not-a-date" {
		t.Fatalf("rfc822Date = %q", got)
	}
	if got := rfc3339Date("not-a-date"); got != "not-a-date" {
		t.Fatalf("rfc3339Date = %q", got)
	}
}

func TestSitemapLastmodFromRealFile(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "x.md")
	if err := os.WriteFile(path, []byte("x"), 0o644); err != nil {
		t.Fatalf("write: %v", err)
	}
	p := parsePost(t, "+++\nslug = \"x\"\n+++\nb\n")
	p.Path = path
	out := RenderSitemap([]*post.Post{p}, "https://site.example")
	if !strings.Contains(out, "<lastmod>") {
		t.Fatalf("sitemap = %s", out)
	}
}

func TestMarshalJSONFeedNoHTMLEscaping(t *testing.T) {
	posts := samplePosts(t)
	feed := RenderJSONFeed(posts, testSite, "https://site.example", "/api/volumen/feed.json")
	out, err := MarshalJSONFeed(feed)
	if err != nil {
		t.Fatalf("MarshalJSONFeed: %v", err)
	}
	if strings.Contains(string(out), `\u0026`) || strings.Contains(string(out), `\u003c`) {
		t.Fatalf("HTML escaping leaked in: %s", out)
	}
	if !strings.Contains(string(out), `"title":"První & <pos>"`) {
		t.Fatalf("literal characters missing: %s", out)
	}
}

// One sitemap document carries at most SitemapURLLimit URLs, the
// sitemaps.org protocol ceiling.
func TestRenderSitemapCapsURLs(t *testing.T) {
	posts := make([]*post.Post, SitemapURLLimit+250)
	for i := range posts {
		meta := frontmatter.NewMeta()
		meta.Set("slug", fmt.Sprintf("post-%d", i))
		posts[i] = post.New(meta, "body")
	}
	out := RenderSitemap(posts, "https://site.example")
	if got := strings.Count(out, "<url>"); got != SitemapURLLimit {
		t.Fatalf("sitemap holds %d URLs, want %d", got, SitemapURLLimit)
	}
}