middleware.go

package main

import (
    "database/sql"
    "encoding/json"
    "fmt"
    "net/http"
)

func tokenMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        decoder := json.NewDecoder(r.Body)
        req := struct {
            APIToken string `json:"api_token"`
        }{""}

        err := decoder.Decode(&req)

        if err != nil {
            failWithStatusCode(err, "Token Error", w, http.StatusForbidden)
        }

        if tokenCache[req.APIToken] == false {
            // Have to get from DB
            apiToken := ""
            queryString := "SELECT current_status FROM users WHERE api_token LIKE $1;"
            stmt, _ := db.Prepare(queryString)
            err = stmt.QueryRow(req.APIToken).Scan(&apiToken)

            if err == sql.ErrNoRows {
                w.WriteHeader(http.StatusForbidden)
                fmt.Fprintf(w, "Token Validation failed")
            }
            tokenCache[apiToken] = true
        }
        next.ServeHTTP(w, r)
    })
}