// Package p contains an HTTP Cloud Function.
package p

import (
    "encoding/json"
    "fmt"
    "html"
    "net/http"
)

// HelloWorld prints the JSON encoded "message" field in the body
// of the request or "Hello, World!" if there isn't one.
func HelloWorld(w http.ResponseWriter, r *http.Request) {
    var d struct {
        Message string `json:"message"`
    }
    if err := json.NewDecoder(r.Body).Decode(&d); err != nil {
        fmt.Fprint(w, "Hello World!")
        return
    }
    if d.Message == "" {
        fmt.Fprint(w, "Hello World!")
        return
    }
    fmt.Fprint(w, html.EscapeString(d.Message))
}