Login light
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/

// See page 194.

// Http3 is an e-commerce server that registers the /list and /price
// endpoints by calling (*http.ServeMux).Handle.
package main

import (
    "fmt"
    "log"
    "net/http"
)

type dollars float32

func (d dollars) String() string { return fmt.Sprintf("$%.2f", d) }

//!+main

func main() {
    db := database{"shoes": 50, "socks": 5}
    mux := http.NewServeMux()
    mux.Handle("/list", http.HandlerFunc(db.list))
    mux.Handle("/price", http.HandlerFunc(db.price))
    log.Fatal(http.ListenAndServe("localhost:8000", mux))
}

type database map[string]dollars

func (db database) list(w http.ResponseWriter, req *http.Request) {
    for item, price := range db {
        fmt.Fprintf(w, "%s: %s\n", item, price)
    }
}

func (db database) price(w http.ResponseWriter, req *http.Request) {
    item := req.URL.Query().Get("item")
    price, ok := db[item]
    if !ok {
        w.WriteHeader(http.StatusNotFound) // 404
        fmt.Fprintf(w, "no such item: %q\n", item)
        return
    }
    fmt.Fprintf(w, "%s\n", price)
}

//!-main

/*
//!+handlerfunc
package http

type HandlerFunc func(w ResponseWriter, r *Request)

func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) {
    f(w, r)
}
//!-handlerfunc
*/