// Command example is a sample application built with Goji. Its goal is to give
// you a taste for what Goji looks like in the real world by artificially using
// all of its features.
//
// In particular, this is a complete working site for gritter.com, a site where
// users can post 140-character "greets". Any resemblance to real websites,
// alive or dead, is purely coincidental.
package main

import (
	"fmt"
	"io"
	"net/http"
	"regexp"
	"strconv"

	"github.com/zenazn/goji"
	"github.com/zenazn/goji/param"
	"github.com/zenazn/goji/web"
)

// Note: the code below cuts a lot of corners to make the example app simple.

func main() {
	// Add routes to the global handler
	goji.Get("/", Root)
	// Fully backwards compatible with net/http's Handlers
	goji.Get("/greets", http.RedirectHandler("/", 301))
	// Use your favorite HTTP verbs
	goji.Post("/greets", NewGreet)
	// Use Sinatra-style patterns in your URLs
	goji.Get("/users/:name", GetUser)
	// Goji also supports regular expressions with named capture groups.
	goji.Get(regexp.MustCompile(`^/greets/(?P<id>\d+)$`), GetGreet)

	// Middleware can be used to inject behavior into your app. The
	// middleware for this application are defined in middleware.go, but you
	// can put them wherever you like.
	goji.Use("PlainText", PlainText)

	// Sub-routes can be used to set custom middleware on sub-applications.
	// Goji's interfaces are completely composable.
	admin := web.New()
	goji.Sub("/admin", admin)
	admin.Use("SuperSecure", SuperSecure)

	// Set up admin routes. Note that sub-routes do *not* mutate the path in
	// any way, so we need to supply full ("/admin" prefixed) paths.
	admin.Get("/admin", AdminRoot)
	admin.Get("/admin/finances", AdminFinances)

	// Use a custom 404 handler
	goji.NotFound(NotFound)

	// Call Serve() at the bottom of your main() function, and it'll take
	// care of everything else for you, including binding to a socket (with
	// automatic support for systemd and Einhorn) and supporting graceful
	// shutdown on SIGINT. Serve() is appropriate for both development and
	// production.
	goji.Serve()
}

// Root route (GET "/"). Print a list of greets.
func Root(w http.ResponseWriter, r *http.Request) {
	// In the real world you'd probably use a template or something.
	io.WriteString(w, "Gritter\n======\n\n")
	for i := len(Greets) - 1; i >= 0; i-- {
		Greets[i].Write(w)
	}
}

// Create a new greet (POST "/greets"). Creates a greet and redirects you to the
// created greet.
//
// To post a new greet, try this at a shell:
// $ now=$(date +'%Y-%m-%mT%H:%M:%SZ')
// $ curl -i -d "user=carl&message=Hello+World&time=$now" localhost:8000/greets
func NewGreet(w http.ResponseWriter, r *http.Request) {
	var greet Greet

	// Parse the POST body into the Greet struct. The format is the same as
	// is emitted by (e.g.) jQuery.param.
	r.ParseForm()
	err := param.Parse(r.Form, &greet)

	if err != nil || len(greet.Message) > 140 {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	// We make no effort to prevent races against other insertions.
	Greets = append(Greets, greet)
	url := fmt.Sprintf("/greets/%d", len(Greets)-1)
	http.Redirect(w, r, url, http.StatusCreated)
}

// Get a given user and her greets (GET "/user/:name")
func GetUser(c web.C, w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, "Gritter\n======\n\n")
	handle := c.UrlParams["name"]
	user, ok := Users[handle]
	if !ok {
		http.Error(w, http.StatusText(404), 404)
		return
	}

	user.Write(w, handle)

	io.WriteString(w, "\nGreets:\n")
	for i := len(Greets) - 1; i >= 0; i-- {
		if Greets[i].User == handle {
			Greets[i].Write(w)
		}
	}
}

// Get a particular greet by ID (GET "/greet/\d+"). Does no bounds checking, so
// will probably panic.
func GetGreet(c web.C, w http.ResponseWriter, r *http.Request) {
	id, err := strconv.Atoi(c.UrlParams["id"])
	if err != nil {
		http.Error(w, http.StatusText(404), 404)
		return
	}
	// This will panic if id is too big. Try it out!
	greet := Greets[id]

	io.WriteString(w, "Gritter\n======\n\n")
	greet.Write(w)
}

// Admin root (GET "/admin/root"). Much secret. Very administrate. Wow.
func AdminRoot(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, "Gritter\n======\n\nSuper secret admin page!\n")
}

// How are we doing? (GET "/admin/finances")
func AdminFinances(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, "Gritter\n======\n\nWe're broke! :(\n")
}

// 404 handler.
func NotFound(w http.ResponseWriter, r *http.Request) {
	http.Error(w, "Umm... have you tried turning it off and on again?", 404)
}