web.go 5.34 KB
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package liber

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"html/template"
	"io"
	"log"
	"net/http"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/gorilla/mux"
)

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

	tpl *template.Template
)

type uiServer struct {
	db      *Database
	storage *FileStorage
}

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

	result, err := s.db.Autocomplete(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) handleShowBook(book *Book, w http.ResponseWriter, req *http.Request) {
	ctx := struct {
		Query string
		Book  *Book
	}{Book: book}
	render("book.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, w http.ResponseWriter, req *http.Request) {
	f, err := s.storage.Open(book.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[book.FileType])
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%d%s\"", book.Id, book.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)
}

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 NewHttpServer(db *Database, storage *FileStorage, 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}

	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/{id:[0-9]+}", uisrv.withBook(uisrv.handleShowBook))
	r.Handle("/dl/{id:[0-9]+}", uisrv.withBook(uisrv.handleDownloadBook))
	r.HandleFunc("/suggest", uisrv.handleAutocomplete)
	r.HandleFunc("/search", uisrv.handleSearch)
	r.HandleFunc("/", uisrv.handleHome)

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