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

// See page 195.

// Http3a is an e-commerce server that registers the /list and /price
// endpoints by calling (*http.ServeMux).HandleFunc.
package main

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

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

type database map[string]int

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

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

/*
//!+handlerfunc
package http

type HandlerFunc func(w ResponseWriter, r *Request)

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