package liber

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"html/template"
	"image"
	_ "image/gif"
	"image/jpeg"
	_ "image/png"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"git.autistici.org/ale/liber/Godeps/_workspace/src/github.com/gorilla/mux"
	"git.autistici.org/ale/liber/Godeps/_workspace/src/github.com/nfnt/resize"
)

var (
	htdocsDir = flag.String("htdocs", "/usr/share/liber/htdocs", "location of static html content")

	tpl *template.Template
)

type uiServer struct {
	db      *Database
	storage *RWFileStorage
	cache   *RWFileStorage
}

type pagination struct {
	PageSize int
	Page     int
	Total    int
}

func (p *pagination) IsFirstPage() bool {
	return p.Page == 0
}

func (p *pagination) IsLastPage() bool {
	return (p.PageSize * (p.Page + 1)) >= p.Total
}

func (p *pagination) Prev() int {
	return p.Page - 1
}

func (p *pagination) Next() int {
	return p.Page + 1
}

func (p *pagination) Start() int {
	return (p.PageSize * p.Page) + 1
}

func (p *pagination) End() int {
	end := (p.PageSize*(p.Page+1) - 1)
	if end >= p.Total {
		end = p.Total - 1
	}
	return end + 1
}

func (s *uiServer) handleSearch(w http.ResponseWriter, req *http.Request) {
	query := req.FormValue("q")
	page, _ := strconv.Atoi(req.FormValue("p"))
	pageSize := 15

	result, err := s.db.Search(query, page*pageSize, pageSize)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	ctx := struct {
		Query      string
		Results    []*Book
		Pagination *pagination
	}{
		Query:   query,
		Results: result.Results,
		Pagination: &pagination{
			PageSize: pageSize,
			Page:     page,
			Total:    result.NumResults,
		},
	}
	render("search.html", w, &ctx)
}

type autocompleteResult struct {
	// Id has to be a string since Javascript can't reliably
	// represent a uint64 (due to its usage of floating point
	// for all numbers).
	Id    string `json:"book_id"`
	Label string `json:"label"`
}

func (s *uiServer) handleSuggest(w http.ResponseWriter, req *http.Request) {
	term := req.FormValue("term")
	if term == "" {
		http.Error(w, "No Query", http.StatusBadRequest)
		return
	}

	result, err := s.db.Suggest(term)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	var out []autocompleteResult
	for _, book := range result.Results {
		out = append(out, autocompleteResult{
			Id:    book.Id.String(),
			Label: book.Metadata.String(),
		})
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(out)
}

func (s *uiServer) withBook(f func(*Book, http.ResponseWriter, *http.Request)) http.HandlerFunc {
	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		vars := mux.Vars(req)
		bookid := ParseID(vars["id"])
		if bookid == 0 {
			http.Error(w, "Bad ID", http.StatusBadRequest)
			return
		}
		book, err := s.db.GetBook(bookid)
		if err != nil {
			http.NotFound(w, req)
			return
		}
		f(book, w, req)
	})
}

func (s *uiServer) withFile(f func(*Book, *File, int, http.ResponseWriter, *http.Request)) http.HandlerFunc {
	return s.withBook(func(book *Book, w http.ResponseWriter, req *http.Request) {
		vars := mux.Vars(req)
		fileIndex, err := strconv.Atoi(vars["fid"])
		if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		files, err := s.db.GetBookFiles(book.Id)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if fileIndex < 0 || fileIndex >= len(files) {
			http.NotFound(w, req)
			return
		}

		f(book, files[fileIndex], fileIndex, w, req)
	})
}

func findEpub(files []*File) int {
	for i, f := range files {
		if f.FileType == ".epub" {
			return i
		}
	}
	return -1
}

func (s *uiServer) handleShowBook(book *Book, w http.ResponseWriter, req *http.Request) {
	files, err := s.db.GetBookFiles(book.Id)
	if err != nil {
		log.Printf("ShowBook(%d): %v", book.Id, err)
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Only offer the online reader if we have an EPUB file.
	epubIndex := findEpub(files)

	// The book's Description, if present, should be rendered
	// directly as HTML. So we deal with it separately.
	ctx := struct {
		Query       string
		Book        *Book
		Files       []*File
		Description template.HTML
		HasEpub     bool
		EpubIndex   int
	}{
		Book:        book,
		Files:       files,
		Description: template.HTML(book.Metadata.Description),
		HasEpub:     (epubIndex >= 0),
		EpubIndex:   epubIndex,
	}
	render("book.html", w, &ctx)
}

func (s *uiServer) handleReadBook(book *Book, file *File, fileIndex int, w http.ResponseWriter, req *http.Request) {
	if file.FileType != ".epub" {
		http.NotFound(w, req)
		return
	}

	ctx := struct {
		Book      *Book
		File      *File
		FileIndex int
	}{
		Book:      book,
		File:      file,
		FileIndex: fileIndex,
	}
	render("reader.html", w, &ctx)
}

var contentTypeMap = map[string]string{
	".epub": "application/epub+zip",
	".mobi": "application/octet-stream",
	".pdf":  "application/pdf",
}

func (s *uiServer) handleDownloadBook(book *Book, file *File, fileIndex int, w http.ResponseWriter, req *http.Request) {
	f, err := s.storage.Open(file.Path)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer f.Close()

	w.Header().Set("ETag", book.Id.String())
	w.Header().Set("Content-Type", contentTypeMap[file.FileType])
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%d%s\"", book.Id, file.FileType))

	http.ServeContent(w, req, "", time.Time{}, f)
}

func (s *uiServer) handleShowCover(book *Book, w http.ResponseWriter, req *http.Request) {
	if book.CoverPath == "" {
		http.NotFound(w, req)
		return
	}

	f, err := s.storage.Open(book.CoverPath)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer f.Close()

	w.Header().Set("ETag", "C"+book.Id.String())
	w.Header().Set("Cache-Control", "public")
	http.ServeContent(w, req, "", time.Time{}, f)
}

var thumbnailSize uint = 150

func makeThumbnail(inputfile string) ([]byte, error) {
	file, err := os.Open(inputfile)
	if err != nil {
		return nil, err
	}
	defer file.Close()
	img, _, err := image.Decode(file)
	if err != nil {
		return nil, err
	}

	thumb := resize.Thumbnail(thumbnailSize, thumbnailSize, img, resize.Lanczos2)
	var buf bytes.Buffer
	if err := jpeg.Encode(&buf, thumb, &jpeg.Options{Quality: 65}); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}

func (s *uiServer) handleShowThumbnail(book *Book, w http.ResponseWriter, req *http.Request) {
	if book.CoverPath == "" {
		http.NotFound(w, req)
		return
	}

	w.Header().Set("Cache-Control", "public")

	cachedPath := s.cache.Path(fmt.Sprintf("%d.thumb.jpg", book.Id))
	if cachedFile, err := s.cache.Open(cachedPath); err == nil {
		// Thumbnail is cached.
		defer cachedFile.Close()
		w.Header().Set("ETag", "T"+book.Id.String())
		http.ServeContent(w, req, "", time.Time{}, cachedFile)
		return
	}

	cachedFile, err := s.cache.Create(cachedPath)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer cachedFile.Close()

	data, err := makeThumbnail(s.storage.Abs(book.CoverPath))
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "image/jpeg")
	w.Header().Set("Content-Length", strconv.Itoa(len(data)))
	w.Header().Set("ETag", "T"+book.Id.String())
	cachedFile.Write(data)
	w.Write(data)
}

func (s *uiServer) handleHome(w http.ResponseWriter, req *http.Request) {
	render("index.html", w, nil)
}

func render(templateName string, w http.ResponseWriter, ctx interface{}) {
	var buf bytes.Buffer
	if err := tpl.ExecuteTemplate(&buf, templateName, ctx); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	io.Copy(w, &buf)
}

func fullURL(req *http.Request) *url.URL {
	u := *req.URL
	u.Host = req.Host
	if req.TLS != nil || req.Header.Get("X-Forwarded-Proto") == "https" {
		u.Scheme = "https"
	} else {
		u.Scheme = "http"
	}
	return &u
}

func handleOpenSearchXml(w http.ResponseWriter, req *http.Request) {
	searchURL := fullURL(req)
	searchURL.Path = "/search"
	searchURL.RawQuery = "q={searchTerms}&pw={startPage}"
	ctx := struct {
		URL string
	}{searchURL.String()}
	w.Header().Set("Content-Type", "application/opensearchdescription+xml")
	render("opensearch_xml.html", w, &ctx)
}

func NewHttpServer(db *Database, storage, cache *RWFileStorage, addr string) *http.Server {
	var err error
	tpl, err = template.New("liber").Funcs(template.FuncMap{
		"join": strings.Join,
	}).ParseGlob(filepath.Join(*htdocsDir, "templates", "*.html"))
	if err != nil {
		log.Fatal(err)
	}

	syncsrv := &syncServer{db, storage}
	uisrv := &uiServer{db, storage, cache}

	r := mux.NewRouter()
	r.Handle("/static/{path:.*}", http.StripPrefix("/static/",
		http.FileServer(http.Dir(filepath.Join(*htdocsDir, "static")))))
	r.HandleFunc("/api/sync/upload", syncsrv.handleSyncUpload).Methods("POST")
	r.HandleFunc("/api/sync/diff", syncsrv.handleDiffRequest).Methods("POST")
	r.Handle("/book/cover/{id:[0-9]+}", uisrv.withBook(uisrv.handleShowCover))
	r.Handle("/book/thumb/{id:[0-9]+}", uisrv.withBook(uisrv.handleShowThumbnail))
	r.Handle("/book/{id:[0-9]+}", uisrv.withBook(uisrv.handleShowBook))
	r.Handle("/read/{id:[0-9]+}/{fid:[0-9]+}", uisrv.withFile(uisrv.handleReadBook))
	r.Handle("/dl/{id:[0-9]+}/{fid:[0-9]+}", uisrv.withFile(uisrv.handleDownloadBook))
	r.HandleFunc("/opensearch.xml", handleOpenSearchXml)
	r.HandleFunc("/suggest", uisrv.handleSuggest)
	r.HandleFunc("/search", uisrv.handleSearch)
	r.HandleFunc("/", uisrv.handleHome)

	return &http.Server{
		Addr:    addr,
		Handler: r,
	}
}