Go Screenshot API

package main

import (
    "encoding/json"
    "fmt"
    "net/http"
    "net/url"
    "time"

    "github.com/gin-gonic/gin"
)

type response struct {
    Data struct {
        Screenshot struct {
            URL string `json:"url"`
        } `json:"screenshot"`
    } `json:"data"`
}

var client = &http.Client{Timeout: 90 * time.Second} // above the API budget: 30s free, 60s pro

func screenshotURL(target string) (string, error) {
    query := url.Values{
        "url":        {target},
        "screenshot": {"true"},
        "meta":       {"false"},
    }

    res, err := client.Get("https://api.microlink.io?" + query.Encode())
    if err != nil {
        return "", err
    }
    defer res.Body.Close()

    if res.StatusCode != http.StatusOK {
        return "", fmt.Errorf("microlink: unexpected status %d", res.StatusCode)
    }

    var body response
    if err := json.NewDecoder(res.Body).Decode(&body); err != nil {
        return "", err
    }

    if body.Data.Screenshot.URL == "" {
        return "", fmt.Errorf("microlink: no screenshot for %s", target)
    }

    return body.Data.Screenshot.URL, nil
}

func main() {
    router := gin.Default()

    // GET /screenshot?url=https://example.com
    router.GET("/screenshot", func(c *gin.Context) {
        image, err := screenshotURL(c.Query("url"))
        if err != nil {
            c.AbortWithError(http.StatusBadGateway, err)
            return
        }
        c.Redirect(http.StatusFound, image)
    })

    router.Run(":3000")
}