/*
 * Copyright (c) 2013, 2014 Conformal Systems LLC <info@conformal.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

package main

import (
	"io/ioutil"
	"net"
	"net/http"
	_ "net/http/pprof"
	"os"
	"runtime"

	"github.com/conformal/btcwallet/chain"
)

var (
	cfg          *config
	shutdownChan = make(chan struct{})
)

func main() {
	// Use all processor cores.
	runtime.GOMAXPROCS(runtime.NumCPU())

	// Work around defer not working after os.Exit.
	if err := walletMain(); err != nil {
		os.Exit(1)
	}
}

// walletMain is a work-around main function that is required since deferred
// functions (such as log flushing) are not called with calls to os.Exit.
// Instead, main runs this function and checks for a non-nil error, at which
// point any defers have already run, and if the error is non-nil, the program
// can be exited with an error exit status.
func walletMain() error {
	// Load configuration and parse command line.  This function also
	// initializes logging and configures it accordingly.
	tcfg, _, err := loadConfig()
	if err != nil {
		return err
	}
	cfg = tcfg
	defer backendLog.Flush()

	if cfg.Profile != "" {
		go func() {
			listenAddr := net.JoinHostPort("", cfg.Profile)
			log.Infof("Profile server listening on %s", listenAddr)
			profileRedirect := http.RedirectHandler("/debug/pprof",
				http.StatusSeeOther)
			http.Handle("/", profileRedirect)
			log.Errorf("%v", http.ListenAndServe(listenAddr, nil))
		}()
	}

	// Create and start HTTP server to serve wallet client connections.
	// This will be updated with the wallet and chain server RPC client
	// created below after each is created.
	server, err := newRPCServer(cfg.SvrListeners, cfg.RPCMaxClients,
		cfg.RPCMaxWebsockets)
	if err != nil {
		log.Errorf("Unable to create HTTP server: %v", err)
		return err
	}
	server.Start()

	// Shutdown the server if an interrupt signal is received.
	addInterruptHandler(server.Stop)

	// Create channel so that the goroutine which opens the chain server
	// connection can pass the conn to the goroutine which opens the wallet.
	// Buffer the channel so sends are not blocked, since if the wallet is
	// not yet created, the wallet open goroutine does not read this.
	chainSvrChan := make(chan *chain.Client, 1)

	go func() {
		// Read CA certs and create the RPC client.
		certs, err := ioutil.ReadFile(cfg.CAFile)
		if err != nil {
			log.Errorf("Cannot open CA file: %v", err)
			close(chainSvrChan)
			return
		}
		rpcc, err := chain.NewClient(activeNet.Params, cfg.RPCConnect,
			cfg.BtcdUsername, cfg.BtcdPassword, certs)
		if err != nil {
			log.Errorf("Cannot create chain server RPC client: %v", err)
			close(chainSvrChan)
			return
		}
		err = rpcc.Start()
		if err != nil {
			log.Warnf("Connection to Bitcoin RPC chain server " +
				"unsuccessful -- available RPC methods will be limited")
		}
		// Even if Start errored, we still add the server disconnected.
		// All client methods will then error, so it's obvious to a
		// client that the there was a connection problem.
		server.SetChainServer(rpcc)

		chainSvrChan <- rpcc
	}()

	// Create a channel to report unrecoverable errors during the loading of
	// the wallet files.  These may include OS file handling errors or
	// issues deserializing the wallet files, but does not include missing
	// wallet files (as that must be handled by creating a new wallet).
	walletOpenErrors := make(chan error)

	go func() {
		defer close(walletOpenErrors)

		// Open wallet structures from disk.
		w, err := openWallet()
		if err != nil {
			if os.IsNotExist(err) {
				// If the keystore file is missing, notify the server
				// that generating new wallets is ok.
				server.SetWallet(nil)
				return
			} else {
				// If the keystore file exists but another error was
				// encountered, we cannot continue.
				log.Errorf("Cannot load wallet files: %v", err)
				walletOpenErrors <- err
				return
			}
		}

		server.SetWallet(w)

		// Start wallet goroutines and handle RPC client notifications
		// if the chain server connection was opened.
		select {
		case chainSvr := <-chainSvrChan:
			w.Start(chainSvr)
		case <-server.quit:
		}
	}()

	// Check for unrecoverable errors during the wallet startup, and return
	// the error, if any.
	err, ok := <-walletOpenErrors
	if ok {
		return err
	}

	// Wait for the server to shutdown either due to a stop RPC request
	// or an interrupt.
	server.WaitForShutdown()
	log.Info("Shutdown complete")
	return nil
}