Scanyonero/server.go

package main

import (
	"fmt"
	"image/jpeg"
	"log"
	"net/http"
	"strconv"

	"github.com/nfnt/resize"
)

type Server struct {
	http.ServeMux

	Documents Queue
}

func NewServer() *Server {
	s := &Server{}

	s.Handle("/", http.FileServer(http.Dir("./static")))
	s.HandleFunc("GET /api/queue-entry-page/{id}/image", s.handleGetQueueEntryImage)
	s.HandleFunc("GET /api/queue-entry-page/{id}/preview", s.handleGetQueueEntryPreview)
	//s.HandleFunc("PUT /documents/{id}", addItem)
	//s.HandleFunc("DELETE /documents/{id}", s.handleRemoveDocument)
	s.HandleFunc("/ws", s.handleWebSocket)

	return s
}

func (s *Server) handleGetQueueEntryImage(w http.ResponseWriter, r *http.Request) {
	var id QueueEntryID
	if i, err := strconv.ParseInt(r.PathValue("id"), 10, 0); err != nil {
		w.WriteHeader(http.StatusBadRequest)
		msg := fmt.Sprintf("Failed to parse document id: %v.", err)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	} else {
		id = QueueEntryID(i)
	}

	s.Documents.Lock()
	defer s.Documents.Unlock()

	entry := s.Documents.QueueEntryByID(id)
	if entry == nil {
		w.WriteHeader(http.StatusNotFound)
		msg := fmt.Sprintf("Failed to find %T with ID %v.", entry, id)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}

	page, ok := entry.QueueEntryData.(QueueEntryDataPage)
	if !ok {
		w.WriteHeader(http.StatusInternalServerError)
		msg := fmt.Sprintf("Entry %d isn't a page.", entry.ID)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}

	if page.Page == nil {
		w.WriteHeader(http.StatusInternalServerError)
		msg := fmt.Sprintf("Entry %d doesn't contain any page data.", entry.ID)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}

	if page.Page.Image == nil {
		w.WriteHeader(http.StatusInternalServerError)
		msg := fmt.Sprintf("Page %d doesn't contain any image.", entry.ID)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}

	w.Header().Set("Content-Type", "image/jpeg")
	if err := jpeg.Encode(w, page.Page.Image, nil); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		msg := fmt.Sprintf("Failed to encode JPEG: %v.", err)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}
}

func (s *Server) handleGetQueueEntryPreview(w http.ResponseWriter, r *http.Request) {
	var id QueueEntryID
	if i, err := strconv.ParseInt(r.PathValue("id"), 10, 0); err != nil {
		w.WriteHeader(http.StatusBadRequest)
		msg := fmt.Sprintf("Failed to parse document id: %v.", err)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	} else {
		id = QueueEntryID(i)
	}

	s.Documents.Lock()
	defer s.Documents.Unlock()

	entry := s.Documents.QueueEntryByID(id)
	if entry == nil {
		w.WriteHeader(http.StatusNotFound)
		msg := fmt.Sprintf("Failed to find %T with ID %v.", entry, id)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}

	page, ok := entry.QueueEntryData.(QueueEntryDataPage)
	if !ok {
		w.WriteHeader(http.StatusInternalServerError)
		msg := fmt.Sprintf("Entry %d isn't a page.", entry.ID)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}

	if page.Page == nil {
		w.WriteHeader(http.StatusInternalServerError)
		msg := fmt.Sprintf("Entry %d doesn't contain any page data.", entry.ID)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}

	if page.Page.Image == nil {
		w.WriteHeader(http.StatusInternalServerError)
		msg := fmt.Sprintf("Page %d doesn't contain any image.", entry.ID)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}

	// Resize image to a preview with a width of about 512 pixels.
	img := resize.Resize(512, 0, page.Page.Image, resize.Lanczos2)

	w.Header().Set("Content-Type", "image/jpeg")
	if err := jpeg.Encode(w, img, nil); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		msg := fmt.Sprintf("Failed to encode JPEG: %v.", err)
		w.Write([]byte(msg))
		log.Print(msg)
		return
	}
}