// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"fmt"
	"io/fs"
	"net/http"
	"net/url"
	"time"

	"golang.org/x/tools/godoc/static"
	"golang.org/x/tools/playground/socket"
	"golang.org/x/tools/present"

	// This will register a handler at /compile that will proxy to the
	// respective endpoints at play.golang.org. This allows the frontend to call
	// these endpoints without needing cross-origin request sharing (CORS).
	// Note that this is imported regardless of whether the endpoints are used or
	// not (in the case of a local socket connection, they are not called).
	_ "golang.org/x/tools/playground"
)

var scripts = []string{"jquery.js", "jquery-ui.js", "playground.js", "play.js"}

// playScript registers an HTTP handler at /play.js that serves all the
// scripts specified by the variable above, and appends a line that
// initializes the playground with the specified transport.
func playScript(fsys fs.FS, transport string) {
	modTime := time.Now()
	var buf bytes.Buffer
	for _, p := range scripts {
		if s, ok := static.Files[p]; ok {
			buf.WriteString(s)
			continue
		}
		b, err := fs.ReadFile(fsys, "static/"+p)
		if err != nil {
			panic(err)
		}
		buf.Write(b)
	}
	fmt.Fprintf(&buf, "\ninitPlayground(new %v());\n", transport)
	b := buf.Bytes()
	http.HandleFunc("/play.js", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-type", "application/javascript")
		http.ServeContent(w, r, "", modTime, bytes.NewReader(b))
	})
}

func initPlayground(fsys fs.FS, origin *url.URL) {
	if !present.PlayEnabled {
		return
	}
	if *usePlayground {
		playScript(fsys, "HTTPTransport")
		return
	}

	playScript(fsys, "SocketTransport")
	http.Handle("/socket", socket.NewHandler(origin))
}

func playable(c present.Code) bool {
	play := present.PlayEnabled && c.Play

	// Restrict playable files to only Go source files when using play.golang.org,
	// since there is no method to execute shell scripts there.
	if *usePlayground {
		return play && c.Ext == ".go"
	}
	return play
}
