package main

import (
    "bytes"
    "fmt"
    "io"
    "io/ioutil"
    "log"
    "mime/multipart"
    "net/http"
    "os"
)

func main() {

    domainPrefix := os.Getenv("VEND_DOMAIN_PREFIX")
    productID := os.Getenv("VEND_PRODUCT_ID")    // this wouldn't usually come from an evironment variable
    filePath := os.Getenv("VEND_IMAGE_FILEPATH") // ditto
    token := os.Getenv("VEND_TOKEN")

    var body bytes.Buffer
    writer := multipart.NewWriter(&body)

    file, err := os.Open(filePath)
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()

    part, err := writer.CreateFormFile("image", filePath)
    if err != nil {
        log.Fatal(err)
    }

    _, err = io.Copy(part, file)
    if err != nil {
        log.Fatal(err)
    }

    err = writer.Close()

    if err != nil {
        log.Fatal(err)
    }

    url := fmt.Sprintf("https://%s.vendhq.com/api/2.0/products/%s/actions/image_upload", domainPrefix, productID)

    req, err := http.NewRequest("POST", url, &body)
    if err != nil {
        log.Fatal(err)
    }

    req.Header.Set("Content-Type", writer.FormDataContentType())
    req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))

    res, err := http.DefaultClient.Do(req)
    if err != nil {
        log.Fatal(err)
    }
    defer res.Body.Close()

    resBody, err := ioutil.ReadAll(res.Body)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(string(resBody))
}