package service

import (
	"archive/zip"
	"bytes"
	"encoding/json"
	"errors"
	"io"
	"os"
	"path/filepath"
	"testing"
)

// readZipEntry 读取 ZIP 内指定名称的文件内容（不存在返回 nil, false）
func readZipEntry(t *testing.T, zr *zip.Reader, name string) ([]byte, bool) {
	t.Helper()
	for _, f := range zr.File {
		if f.Name == name {
			rc, err := f.Open()
			if err != nil {
				t.Fatalf("open zip entry %s: %v", name, err)
			}
			defer rc.Close()
			data, err := io.ReadAll(rc)
			if err != nil {
				t.Fatalf("read zip entry %s: %v", name, err)
			}
			return data, true
		}
	}
	return nil, false
}

func buildExportZip(t *testing.T, exp *LibraryExport) *zip.Reader {
	t.Helper()
	var buf bytes.Buffer
	if err := exp.WriteZip(&buf); err != nil {
		t.Fatalf("write zip: %v", err)
	}
	zr, err := zip.NewReader(bytes.NewReader(buf.Bytes()), int64(buf.Len()))
	if err != nil {
		t.Fatalf("read exported zip: %v", err)
	}
	return zr
}

// seedBookForExport 造一本含章节（章 + 小节）、附件与本地封面的书籍
func seedBookForExport(t *testing.T, s *LibraryService, uploads string) (docID uint, storedName string) {
	t.Helper()
	pub := true
	doc, err := s.Create(&LibraryInput{Slug: "dao-jia", Title: "道家研究", Author: "老子", Description: "# 介绍"})
	if err != nil {
		t.Fatalf("create doc: %v", err)
	}

	coverDir := filepath.Join(uploads, "images")
	if err := os.MkdirAll(coverDir, 0o755); err != nil {
		t.Fatalf("mkdir uploads: %v", err)
	}
	coverBytes := encodeJPEGBytes(t, 120, 160)
	if err := os.WriteFile(filepath.Join(coverDir, "cover.jpg"), coverBytes, 0o644); err != nil {
		t.Fatalf("write cover: %v", err)
	}
	if _, err := s.Update(doc.ID, &LibraryInput{
		Slug: "dao-jia", Title: "道家研究", Author: "老子", Description: "# 介绍",
		CoverURL: "/uploads/images/cover.jpg", CoverWidth: 120, CoverHeight: 160,
		Published: &pub,
	}); err != nil {
		t.Fatalf("update cover: %v", err)
	}

	chapter, err := s.CreateSection(doc.ID, &SectionInput{Title: "第一章", Content: "章正文"})
	if err != nil {
		t.Fatalf("create chapter: %v", err)
	}
	if _, err := s.CreateSection(doc.ID, &SectionInput{
		ParentID: &chapter.ID, Title: "小节", Content: "小节正文",
	}); err != nil {
		t.Fatalf("create section: %v", err)
	}

	f, err := s.AddFile(doc.ID, 1, "manual.epub", bytes.NewReader([]byte("EPUB-FILE-BYTES")))
	if err != nil {
		t.Fatalf("add file: %v", err)
	}
	return doc.ID, f.StoredName
}

func TestLibraryExportBook(t *testing.T) {
	s, _ := newLibraryTestService(t)
	uploads := t.TempDir()
	s.WithUploadsDir(uploads)
	docID, storedName := seedBookForExport(t, s, uploads)

	exp, err := s.BuildBookExport(docID)
	if err != nil {
		t.Fatalf("build export: %v", err)
	}
	defer exp.Close()
	if exp.Filename != "dao-jia.zip" {
		t.Fatalf("filename = %q, want dao-jia.zip", exp.Filename)
	}
	zr := buildExportZip(t, exp)

	raw, ok := readZipEntry(t, zr, "book.json")
	if !ok {
		t.Fatal("缺少 book.json")
	}
	var manifest libraryExportManifest
	if err := json.Unmarshal(raw, &manifest); err != nil {
		t.Fatalf("parse book.json: %v", err)
	}
	if manifest.Format != libraryExportBookFormat || manifest.FormatVersion != libraryExportVersion {
		t.Fatalf("清单格式异常: %s v%d", manifest.Format, manifest.FormatVersion)
	}
	b := manifest.Doc
	if b == nil {
		t.Fatal("book.json 缺少 doc")
	}
	if b.Title != "道家研究" || b.Slug != "dao-jia" || b.Author != "老子" || !b.Published {
		t.Fatalf("元信息导出不正确: %+v", b)
	}
	if b.CoverFile != "cover.jpg" || b.CoverWidth != 120 || b.CoverHeight != 160 {
		t.Fatalf("封面信息导出不正确: %+v", b)
	}
	if len(b.Sections) != 2 || b.Sections[0].Key != "s0" || b.Sections[1].ParentKey != "s0" {
		t.Fatalf("章节树导出不正确: %+v", b.Sections)
	}
	if len(b.Files) != 1 || b.Files[0].Stored != "files/"+storedName || b.Files[0].Missing {
		t.Fatalf("附件清单导出不正确: %+v", b.Files)
	}

	if data, ok := readZipEntry(t, zr, "files/"+storedName); !ok || string(data) != "EPUB-FILE-BYTES" {
		t.Fatalf("附件内容导出不正确（ok=%v）", ok)
	}
	if data, ok := readZipEntry(t, zr, "cover.jpg"); !ok || !bytes.HasPrefix(data, []byte{0xff, 0xd8, 0xff}) {
		t.Fatalf("封面内容导出不正确（ok=%v）", ok)
	}
	// 单本包不应出现全库索引
	if _, ok := readZipEntry(t, zr, "library.json"); ok {
		t.Fatal("单本包不应包含 library.json")
	}
}

func TestLibraryExportAll(t *testing.T) {
	s, _ := newLibraryTestService(t)
	uploads := t.TempDir()
	s.WithUploadsDir(uploads)
	docID, storedName := seedBookForExport(t, s, uploads)
	_ = docID

	exp, err := s.BuildAllExport()
	if err != nil {
		t.Fatalf("build all export: %v", err)
	}
	defer exp.Close()
	zr := buildExportZip(t, exp)

	raw, ok := readZipEntry(t, zr, "library.json")
	if !ok {
		t.Fatal("缺少 library.json")
	}
	var manifest libraryExportManifest
	if err := json.Unmarshal(raw, &manifest); err != nil {
		t.Fatalf("parse library.json: %v", err)
	}
	if manifest.Format != libraryExportFormat || len(manifest.Docs) != 1 {
		t.Fatalf("全库索引异常: %+v", manifest)
	}
	idx := manifest.Docs[0]
	if idx.Dir != "docs/dao-jia/" || idx.FileCount != 1 || idx.SectionCount != 2 {
		t.Fatalf("索引条目异常: %+v", idx)
	}

	bookRaw, ok := readZipEntry(t, zr, "docs/dao-jia/book.json")
	if !ok {
		t.Fatal("缺少 docs/dao-jia/book.json")
	}
	var book libraryExportBook
	if err := json.Unmarshal(bookRaw, &book); err != nil {
		t.Fatalf("parse nested book.json: %v", err)
	}
	if book.Slug != "dao-jia" || book.CoverFile != "cover.jpg" {
		t.Fatalf("嵌套书籍清单异常: %+v", book)
	}
	if _, ok := readZipEntry(t, zr, "docs/dao-jia/files/"+storedName); !ok {
		t.Fatal("缺少嵌套附件")
	}
	if _, ok := readZipEntry(t, zr, "docs/dao-jia/cover.jpg"); !ok {
		t.Fatal("缺少嵌套封面")
	}
}

func TestLibraryExportMissingDoc(t *testing.T) {
	s, _ := newLibraryTestService(t)
	if _, err := s.BuildBookExport(999); !errors.Is(err, ErrLibraryNotFound) {
		t.Fatalf("不存在的条目应返回 ErrLibraryNotFound，got %v", err)
	}
}