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

package payloads

import (
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"sourcedock.dev/petrbalvin/interpres/v2"
	"sourcedock.dev/petrbalvin/volumen/internal/frontmatter"
	"sourcedock.dev/petrbalvin/volumen/internal/post"
	"sourcedock.dev/petrbalvin/volumen/internal/store"
)

// An edit through the form only rewrites the fields the form names: a
// key the form does not carry keeps the comment written above it.
func TestPostFromParamsKeepsUntouchedComments(t *testing.T) {
	existing, _, err := frontmatter.Parse("+++\ntitle = \"Old\"\nslug = \"old\"\nlang = \"en\"\n\n# chapters live here\n[[chapters]]\nx = 1\n+++\n\nbody\n")
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	p, err := PostFromParams(map[string]string{
		"title": "New", "slug": "old", "lang": "en",
	}, post.New(existing, "body\n"))
	if err != nil {
		t.Fatalf("PostFromParams: %v", err)
	}
	if p.Title() != "New" {
		t.Fatalf("title = %q, want New", p.Title())
	}
	out, err := frontmatter.Dump(p.Metadata, "body\n")
	if err != nil {
		t.Fatalf("Dump: %v", err)
	}
	if !strings.Contains(out, "# chapters live here") || !strings.Contains(out, "[[chapters]]") {
		t.Fatalf("untouched frontmatter lost its comment:\n%s", out)
	}
}

// Every form field the editor saves is a key the engine consumes, so
// none of them may leak into the API's fields object: this guards the
// two lists against drifting apart.
func TestMetadataOrderStaysReserved(t *testing.T) {
	for _, key := range metadataOrder {
		if !post.ReservedMetadata[key] {
			t.Fatalf("form key %q is not in post.ReservedMetadata", key)
		}
	}
}

func newStoreWithPosts(t *testing.T, files map[string]string) *store.Store {
	t.Helper()
	dir := filepath.Join(t.TempDir(), "posts")
	if err := os.MkdirAll(dir, 0o755); err != nil {
		t.Fatalf("mkdir: %v", err)
	}
	for name, body := range files {
		target := filepath.Join(dir, name)
		if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
			t.Fatalf("mkdir: %v", err)
		}
		if err := os.WriteFile(target, []byte(body), 0o644); err != nil {
			t.Fatalf("write: %v", err)
		}
	}
	return store.New(store.Options{ContentDir: dir, DefaultLang: "en", RevisionLimit: 10})
}

const publishedFile = `+++
title = "Published"
slug = "published"
date = 2026-08-18
lang = "cs"
tags = ["go", "blog"]
series = "S"
series_order = 2
+++
published body
`

const draftFile = `+++
title = "Draft"
slug = "draft"
draft = true
+++
draft body
`

const scheduledFile = `+++
title = "Future"
slug = "future"
publish_at = 2999-01-01
+++
future body
`

func TestPublishedPostsExcludesDraftsAndScheduled(t *testing.T) {
	s := newStoreWithPosts(t, map[string]string{
		"published.md": publishedFile,
		"draft.md":     draftFile,
		"future.md":    scheduledFile,
	})
	posts := PublishedPosts(s)
	if len(posts) != 1 || posts[0].Slug() != "published" {
		t.Fatalf("published = %v", posts)
	}
}

func TestPublishedPostsSortsNewestFirst(t *testing.T) {
	s := newStoreWithPosts(t, map[string]string{
		"old.md": "+++\nslug = \"old\"\ndate = 2020-01-01\n+++\nx\n",
		"new.md": "+++\nslug = \"new\"\ndate = 2026-01-01\n+++\nx\n",
	})
	posts := PublishedPosts(s)
	if len(posts) != 2 || posts[0].Slug() != "new" {
		t.Fatalf("order = %v, %v", posts[0].Slug(), posts[1].Slug())
	}
}

func TestFilterPosts(t *testing.T) {
	s := newStoreWithPosts(t, map[string]string{
		"a.md": "+++\nslug = \"a\"\nlang = \"cs\"\ntags = [\"go\"]\ntitle = \"Go tipy\"\n+++\nbody here\n",
		"b.md": "+++\nslug = \"b\"\nlang = \"en\"\ntags = [\"life\"]\ntitle = \"Hello\"\n+++\nother\n",
		"c.md": "+++\nslug = \"c\"\nall_langs = true\nlang = \"cs\"\ntags = [\"go\"]\ntitle = \"CS GO\"\n+++\nxx\n",
	})
	all := PublishedPosts(s)
	if got := FilterPosts(all, "en", "", ""); len(got) != 2 {
		t.Fatalf("lang filter = %v", slugs(got))
	}
	if got := FilterPosts(all, "", "go", ""); len(got) != 2 {
		t.Fatalf("tag filter = %v", slugs(got))
	}
	if got := FilterPosts(all, "", "", "body here"); len(got) != 1 || got[0].Slug() != "a" {
		t.Fatalf("query filter = %v", slugs(got))
	}
	if got := FilterPosts(all, "", "", "HELLO"); len(got) != 1 || got[0].Slug() != "b" {
		t.Fatalf("case-insensitive query = %v", slugs(got))
	}
}

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 slugs(posts []*post.Post) []string {
	out := make([]string, len(posts))
	for i, p := range posts {
		out[i] = p.Slug()
	}
	return out
}

func TestPostsPayloadPagination(t *testing.T) {
	files := map[string]string{}
	for i, slug := range []string{"one", "two", "three", "four", "five"} {
		files[slug+".md"] = "+++\nslug = \"" + slug + "\"\ntitle = \"" + slug +
			"\"\ndate = 2026-01-0" + string(rune('1'+i)) + "\n+++\nx\n"
	}
	s := newStoreWithPosts(t, files)

	first, ok := PostsPayload(s, "", "", "", 1, 2, "").(PageList)
	if !ok {
		t.Fatal("page mode must return a PageList")
	}
	if first.Total != 5 || first.Page != 1 || !first.HasNext || first.HasPrev {
		t.Fatalf("first page = %+v", first)
	}
	if len(first.Posts) != 2 {
		t.Fatalf("posts = %v", first.Posts)
	}
	if !first.HasNext {
		t.Fatalf("first page must have a next page: %+v", first)
	}

	last, ok := PostsPayload(s, "", "", "", 3, 2, "").(PageList)
	if !ok {
		t.Fatal("page mode must return a PageList")
	}
	if last.HasNext || !last.HasPrev {
		t.Fatalf("last page = %+v", last)
	}

	cursorPage, ok := PostsPayload(s, "", "", "", 1, 2, "five").(CursorList)
	if !ok {
		t.Fatal("cursor mode must return a CursorList")
	}
	if cursorPage.NextCursor == nil {
		t.Fatalf("cursor page = %+v", cursorPage)
	}
}

func TestPostsPayloadLimitClamping(t *testing.T) {
	s := newStoreWithPosts(t, map[string]string{
		"a.md": "+++\nslug = \"a\"\n+++\nx\n",
	})
	huge, ok := PostsPayload(s, "", "", "", 1, 5000, "").(PageList)
	if !ok || huge.PageSize != 100 {
		t.Fatalf("page_size = %v, want 100", huge.PageSize)
	}
	zero, ok := PostsPayload(s, "", "", "", 1, 0, "").(PageList)
	if !ok || zero.PageSize != 1 {
		t.Fatalf("page_size = %v, want 1", zero.PageSize)
	}
}

func TestPostsPayloadIsEmpty(t *testing.T) {
	s := newStoreWithPosts(t, nil)
	if !IsEmpty(PostsPayload(s, "", "", "", 1, 20, "")) {
		t.Fatal("empty store must yield an empty payload")
	}
	if IsEmpty("not a payload") {
		t.Fatal("unknown types count as empty")
	}
}

func TestTagCountsAndSeries(t *testing.T) {
	s := newStoreWithPosts(t, map[string]string{
		"a.md": "+++\nslug = \"a\"\ntags = [\"go\", \"blog\"]\nseries = \"S\"\nseries_order = 2\ndate = 2026-01-02\n+++\nx\n",
		"b.md": "+++\nslug = \"b\"\ntags = [\"go\"]\nseries = \"S\"\nseries_order = 1\ndate = 2026-01-03\n+++\nx\n",
		"c.md": "+++\nslug = \"c\"\ntags = [\"zz\"]\nseries = \"T\"\ndate = 2026-01-04\n+++\nx\n",
	})
	tags := BuildTagCounts(PublishedPosts(s))
	if len(tags) != 3 || tags[0].Name != "go" || tags[0].Count != 2 {
		t.Fatalf("tags = %v", tags)
	}
	series := BuildSeriesList(s)
	if len(series) != 2 || series[0].Name != "S" || series[0].Count != 2 {
		t.Fatalf("series = %v", series)
	}
	posts := SeriesPosts(s, "S")
	if len(posts) != 2 || posts[0].Slug() != "b" || posts[1].Slug() != "a" {
		t.Fatalf("series posts = %v", slugs(posts))
	}
}

func TestSeriesPostsOrderFallbacks(t *testing.T) {
	s := newStoreWithPosts(t, map[string]string{
		"a.md": "+++\nslug = \"a\"\nseries = \"S\"\ndate = 2026-01-02\n+++\nx\n",
		"b.md": "+++\nslug = \"b\"\nseries = \"S\"\ndate = 2026-01-01\n+++\nx\n",
	})
	posts := SeriesPosts(s, "S")
	// No series_order: date ascending.
	if posts[0].Slug() != "b" || posts[1].Slug() != "a" {
		t.Fatalf("order = %v", slugs(posts))
	}
}

func TestPresenceAndParsers(t *testing.T) {
	if Presence("  x ") != "x" || Presence(nil) != "" || Presence("   ") != "" {
		t.Fatal("Presence wrong")
	}
	if _, ok := ParseDate("2026-08-18"); !ok {
		t.Fatal("ParseDate failed")
	}
	if _, ok := ParseDate("nonsense"); ok {
		t.Fatal("ParseDate accepted nonsense")
	}
	if _, ok := ParseDate(""); ok {
		t.Fatal("ParseDate accepted empty")
	}
	if n, ok := ParseInt(" 42 "); !ok || n != 42 {
		t.Fatalf("ParseInt = %d, %v", n, ok)
	}
	if _, ok := ParseInt("x"); ok {
		t.Fatal("ParseInt accepted nonsense")
	}
	if _, ok := ParseInt(""); ok {
		t.Fatal("ParseInt accepted empty")
	}
	tags := ParseTags("go, blog ,,rust")
	if len(tags) != 3 || tags[1] != "blog" {
		t.Fatalf("ParseTags = %v", tags)
	}
	if ParseTags("") != nil {
		t.Fatal("ParseTags empty should be nil")
	}
}

func TestPostFromParams(t *testing.T) {
	form := map[string]string{
		"title":             "Nadpis",
		"slug":              "nadpis",
		"lang":              "cs",
		"author":            "Petr",
		"fediverse_creator": "@petr@social",
		"date":              "2026-08-18",
		"publish_at":        "",
		"tags":              "go, blog",
		"excerpt":           "Perex",
		"cover":             "/media/c.webp",
		"cover_alt":         "alt",
		"cover_caption":     "caption",
		"series":            "S",
		"series_order":      "3",
		"draft":             "on",
		"all_langs":         "on",
		"body":              "obsah",
	}
	p, err := PostFromParams(form, nil)
	if err != nil {
		t.Fatalf("PostFromParams: %v", err)
	}
	if p.Slug() != "nadpis" || p.Title() != "Nadpis" || p.Body != "obsah" {
		t.Fatalf("post = %v", p)
	}
	if !p.Draft() || !p.AllLangs() {
		t.Fatal("flags not set")
	}
	if p.DateString() != "2026-08-18" {
		t.Fatalf("date = %q", p.DateString())
	}
	if order, ok := p.SeriesOrder(); !ok || order != 3 {
		t.Fatalf("series_order = %d, %v", order, ok)
	}
	if _, present := p.Metadata.Get("publish_at"); present {
		t.Fatal("empty publish_at kept")
	}
	if len(p.Tags()) != 2 {
		t.Fatalf("tags = %v", p.Tags())
	}

	// Cleaned metadata drops empties and keeps date as a bare TOML date.
	out, err := p.ToFile()
	if err != nil {
		t.Fatalf("ToFile: %v", err)
	}
	if !strings.Contains(out, "date = 2026-08-18") {
		t.Fatalf("date not written bare:\n%s", out)
	}
	if strings.Contains(out, "excerpt = \"\"") {
		t.Fatalf("empty values kept:\n%s", out)
	}
}

func TestPostFromParamsKeepsExistingPathAndSlug(t *testing.T) {
	existing := parsePost(t, "+++\nslug = \"old\"\n+++\nx\n")
	p, err := PostFromParams(map[string]string{"title": "T", "body": "b"}, existing)
	if err != nil {
		t.Fatalf("PostFromParams: %v", err)
	}
	if p.Slug() != "old" {
		t.Fatalf("slug = %q, want fallback to existing", p.Slug())
	}
	if p.Path != existing.Path {
		t.Fatalf("path not carried: %q", p.Path)
	}
}

func TestCreationError(t *testing.T) {
	s := newStoreWithPosts(t, map[string]string{
		"taken.md": "+++\nslug = \"taken\"\n+++\nx\n",
	})
	newPost := func(slug, lang, fediverse string) *post.Post {
		meta := frontmatter.NewMeta()
		meta.Set("slug", slug)
		if lang != "" {
			meta.Set("lang", lang)
		}
		if fediverse != "" {
			meta.Set("fediverse_creator", fediverse)
		}
		return post.New(meta, "x")
	}

	check := func(err error, want string) {
		t.Helper()
		if want == "" {
			if err != nil {
				t.Fatalf("err = %v, want nil", err)
			}
			return
		}
		validation, ok := errors.AsType[*ValidationError](err)
		if err == nil || !ok {
			t.Fatalf("err = %v, want a ValidationError", err)
		}
		if validation.Message != want {
			t.Fatalf("message = %q, want %q", validation.Message, want)
		}
	}

	check(CreationError(newPost("", "", ""), s, nil), "Slug is required.")
	check(CreationError(newPost("Upper!", "", ""), s, nil), "Invalid slug.")
	if err := CreationError(newPost(strings.Repeat("a", MaxSlugLength+1), "", ""), s, nil); err == nil {
		t.Fatal("want slug length error")
	}
	check(CreationError(newPost("ok", "bad lang!", ""), s, nil), "Invalid language.")
	check(CreationError(newPost("taken", "", ""), s, nil), "A post with that slug already exists.")
	// Editing the same post keeps its own slug.
	existing := s.Find("taken", "")
	check(CreationError(newPost("taken", "", ""), s, existing), "")
	check(CreationError(newPost("fresh", "", "not-a-handle"), s, nil),
		"Fediverse creator must look like @user@host.")
	check(CreationError(newPost("fresh", "cs", "@ok@host"), s, nil), "")
	check(CreationError(newPost("a.b_c-d", "", ""), s, nil), "")
}

func TestSlugAndLangRegexes(t *testing.T) {
	if SlugRegex.MatchString("-leading") || SlugRegex.MatchString("trailing-") || SlugRegex.MatchString("UPPER") {
		t.Fatal("SlugRegex too permissive")
	}
	if !SlugRegex.MatchString("a") || !SlugRegex.MatchString("a.b-c_d") {
		t.Fatal("SlugRegex too strict")
	}
	if LangRegex.MatchString("cs CS") || !LangRegex.MatchString("pt-BR") {
		t.Fatal("LangRegex wrong")
	}
}

func TestLocalDateDumpShape(t *testing.T) {
	// Guard: form dates must serialise as bare TOML dates, not RFC3339.
	d := time.Date(2026, 3, 4, 0, 0, 0, 0, time.UTC)
	meta := frontmatter.NewMeta()
	meta.Set("date", interpres.LocalDate{Time: d})
	out, err := frontmatter.Dump(meta, "x")
	if err != nil {
		t.Fatalf("Dump: %v", err)
	}
	if !strings.Contains(out, "date = 2026-03-04") {
		t.Fatalf("out = %s", out)
	}
}

// A malformed date in the form must be rejected rather than dropped:
// dropping it would delete an inherited schedule and publish the post.
func TestPostFromParamsRejectsAMalformedDate(t *testing.T) {
	existing := parsePost(t, "+++\nslug = \"s\"\ntitle = \"T\"\npublish_at = 2999-01-01\n+++\nx\n")
	p, err := PostFromParams(map[string]string{"title": "T", "publish_at": "not a date", "body": "b"}, existing)
	if err == nil {
		t.Fatal("a malformed publish_at was accepted")
	}
	if want := "publish_at must be an ISO 8601 date."; err.Error() != want {
		t.Fatalf("error = %q, want %q", err.Error(), want)
	}
	// The post comes back for the form re-render; the schedule is kept
	// because the form value never reached the metadata.
	if _, ok := p.DueAt(); !ok {
		t.Fatal("the inherited schedule was dropped on a rejected form")
	}
}

// Two published posts may share a slug across languages; the cursor must
// then name the exact post or the walk serves the second variant twice
// and, with a tight limit, never advances.
func TestCursorPaginationAcrossSameSlugTranslations(t *testing.T) {
	s := newStoreWithPosts(t, map[string]string{
		"en/shared.md": "+++\nslug = \"shared\"\ntitle = \"EN\"\nlang = \"en\"\ndate = 2026-01-03\n+++\nx\n",
		"cs/shared.md": "+++\nslug = \"shared\"\ntitle = \"CS\"\nlang = \"cs\"\ndate = 2026-01-02\n+++\nx\n",
		"other.md":     "+++\nslug = \"other\"\ntitle = \"O\"\ndate = 2026-01-01\n+++\nx\n",
	})
	seen := map[string]bool{}
	// The walk starts after the first variant, as it would for a client
	// that paged one post at a time and just received the EN variant.
	cursor := "shared"
	pages := 0
	for {
		payload := PostsPayload(s, "", "", "", 1, 1, cursor).(CursorList)
		for _, post := range payload.Posts {
			key := post.Slug + "|" + post.Lang
			if seen[key] {
				t.Fatalf("post %s served twice", key)
			}
			seen[key] = true
		}
		pages++
		if payload.NextCursor == nil {
			break
		}
		cursor = *payload.NextCursor
		if pages > 10 {
			t.Fatal("the cursor walk does not terminate")
		}
	}
	if len(seen) != 2 {
		t.Fatalf("walked %d posts, want the CS variant and one more: %v", len(seen), seen)
	}
}

// Invalid UTF-8 typed into a form field is rejected rather than saved:
// the writer would otherwise silently replace the bytes with U+FFFD.
func TestPostFromParamsRejectsInvalidUTF8(t *testing.T) {
	p, err := PostFromParams(map[string]string{
		"title": "Bad \xff\xfe", "slug": "utf8-test", "body": "ok",
	}, nil)
	if err == nil {
		t.Fatal("invalid UTF-8 was accepted")
	}
	if want := "title must be valid UTF-8 text."; err.Error() != want {
		t.Fatalf("error = %q, want %q", err.Error(), want)
	}
	if p == nil {
		t.Fatal("the post must come back for the form re-render")
	}
	// A clean body alone is fine.
	if _, err := PostFromParams(map[string]string{"title": "Ok", "body": "ok"}, nil); err != nil {
		t.Fatalf("clean form rejected: %v", err)
	}
}