Tagbox combined with imagesnap using Go

tagbox-imagesnap.go

package main

import (
	"bufio"
	"bytes"
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"time"

	"github.com/machinebox/sdk-go/tagbox"
)

var (
	images   = map[string][]byte{}
	imageURL *url.URL
	tbox     *tagbox.Client
)

func main() {
	var ip, port, tb string

	flag.StringVar(&ip, "ip", "10.0.0.86", "")
	flag.StringVar(&port, "port", "8081", "")
	flag.StringVar(&tb, "tb", "http://localhost:8080", "Tagbox URL")

	flag.Parse()

	imageURL = &url.URL{Scheme: "http", Host: ip + ":" + port, Path: "/image"}

	http.HandleFunc("/image", image)
	http.HandleFunc("/", index)

	tbox = tagbox.New(tb)

	fmt.Fprintf(os.Stderr, "Listening on http://0.0.0.0:%s\n", port)

	http.ListenAndServe(":"+port, nil)
}

func snap(ctx context.Context, w io.Writer) error {
	cmd := exec.CommandContext(ctx, "imagesnap", "-w", "1", "-")
	cmd.Stdout = w

	return cmd.Run()
}

func image(w http.ResponseWriter, r *http.Request) {
	at := requestAt(r, time.Now().UTC())

	if b, found := images[at]; found {
		w.Write(b)
		return
	}

	var buf bytes.Buffer

	bw := bufio.NewWriter(&buf)

	if err := snap(r.Context(), bw); err != nil {
		log.Println("[ERROR] capturing webcam", err)
		return
	}

	bw.Flush()

	b := buf.Bytes()

	images[at] = b

	w.Write(b)
}

func index(w http.ResponseWriter, r *http.Request) {
	timestamp := time.Now().UTC()
	meta := Meta{"timestamp": timestamp}

	u := imageURL

	u.RawQuery = "at=" + requestAt(r, timestamp)

	fmt.Fprintf(os.Stderr, "Checking %s\n", u.String())

	tags, err := tbox.CheckURL(u)
	if err != nil {
		log.Println("[ERROR]", err)

		writeJSON(w, errorResponse(err, 500, meta), 500)

		return
	}

	resp := Response{
		Meta: meta,
		Data: Data{
			"image": u.String(),
			"tags":  tags,
		},
	}

	go func() {
		for _, tag := range tags {
			if tag.Confidence > 0.3 {
				exec.Command("say", tag.Tag, "-v", "Samantha", "-r", "160").Run()
				break
			}
		}
	}()

	json.NewEncoder(os.Stdout).Encode(resp)

	writeJSON(w, resp)

}

func requestAt(r *http.Request, t time.Time) string {
	if at := r.URL.Query().Get("at"); at != "" {
		return at
	}

	return fmt.Sprintf("%d", t.Nanosecond())
}

func writeJSON(w http.ResponseWriter, v interface{}, statuses ...int) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Add("Vary", "Accept-Encoding")

	if len(statuses) > 0 {
		w.WriteHeader(statuses[0])
	}

	enc := json.NewEncoder(w)

	enc.SetIndent("", "  ")
	enc.Encode(v)
}

type Response struct {
	Meta   Meta    `json:"meta,omitempty"`
	Data   Data    `json:"data,omitempty"`
	Errors []Error `json:"errors,omitempty"`
}

func errorResponse(err error, status int, meta Meta) Response {
	return Response{
		Meta: meta,
		Errors: []Error{
			{
				Status: status,
				Title:  http.StatusText(status),
				Detail: err.Error(),
			},
		},
	}
}

// Meta is a meta object that contains non-standard meta-information.
type Meta map[string]interface{}

// Data is the primary data of the Response
type Data map[string]interface{}

// Error objects provide additional information about problems encountered while performing an operation.
type Error struct {
	Status int    `json:"status"`
	Title  string `json:"title"`
	Detail string `json:"detail,omitempty"`
}

{
    "meta": {
        "timestamp": "2017-09-01T17:19:35.557356552Z"
    },
    "data": {
        "image": "http://10.0.0.86:8081/image?at=557356552",
        "tags": [
            {
                "Tag": "cellular_telephone",
                "Confidence": 0.533503532409668
            },
            {
                "Tag": "iPod",
                "Confidence": 0.22914648056030273
            },
            {
                "Tag": "microphone",
                "Confidence": 0.014935246668756008
            },
            {
                "Tag": "hand_blower",
                "Confidence": 0.013065827079117298
            },
            {
                "Tag": "banjo",
                "Confidence": 0.008280351758003235
            }
        ]
    }
}

{
    "meta": {
        "timestamp": "2017-09-01T17:29:52.302810177Z"
    },
    "data": {
        "image": "http://10.0.0.86:8081/image?at=302810177",
        "tags": [
            {
                "Tag": "orange",
                "Confidence": 0.9756798148155212
            },
            {
                "Tag": "ping-pong_ball",
                "Confidence": 0.009037220850586891
            },
            {
                "Tag": "lemon",
                "Confidence": 0.0031082637142390013
            },
            {
                "Tag": "pomegranate",
                "Confidence": 0.002462725155055523
            },
            {
                "Tag": "banana",
                "Confidence": 0.001104470225982368
            }
        ]
    }
}

{
    "meta": {
        "timestamp": "2017-09-01T17:37:40.171699873Z"
    },
    "data": {
        "image": "http://10.0.0.86:8081/image?at=171699873",
        "tags": [
            {
                "Tag": "rubber_eraser",
                "Confidence": 0.36174893379211426
            },
            {
                "Tag": "paintbrush",
                "Confidence": 0.17667531967163086
            },
            {
                "Tag": "screwdriver",
                "Confidence": 0.13990812003612518
            },
            {
                "Tag": "syringe",
                "Confidence": 0.12272959202528
            },
            {
                "Tag": "pencil_sharpener",
                "Confidence": 0.049953900277614594
            }
        ]
    }
}

Not totally sure how it “figured” out that the pen has a rubber eraser tip… even with such a low confidence value.

{
    "meta": {
        "timestamp": "2017-09-01T17:45:47.514745238Z"
    },
    "data": {
        "image": "http://10.0.0.86:8081/image?at=514745238",
        "tags": [
            {
                "Tag": "king_penguin",
                "Confidence": 0.9592017531394958
            },
            {
                "Tag": "killer_whale",
                "Confidence": 0.020975982770323753
            },
            {
                "Tag": "toucan",
                "Confidence": 0.005348627455532551
            },
            {
                "Tag": "sombrero",
                "Confidence": 0.0010137950303032994
            },
            {
                "Tag": "goose",
                "Confidence": 0.0009246725821867585
            }
        ]
    }
}

{
    "meta": {
        "timestamp": "2017-09-01T18:06:32.109913137Z"
    },
    "data": {
        "image": "http://10.0.0.86:8081/image?at=109913137",
        "tags": [
            {
                "Tag": "coffee_mug",
                "Confidence": 0.7345199584960938
            },
            {
                "Tag": "cup",
                "Confidence": 0.1498795747756958
            },
            {
                "Tag": "toilet_tissue",
                "Confidence": 0.027606995776295662
            },
            {
                "Tag": "cowboy_hat",
                "Confidence": 0.023174552246928215
            },
            {
                "Tag": "sombrero",
                "Confidence": 0.018557647243142128
            }
        ]
    }
}