// Copyright (c) 2013-2017 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
	"net"
	"os"
	"os/user"
	"path/filepath"
	"runtime"
	"sort"
	"strings"
	"time"

	flags "github.com/jessevdk/go-flags"
	"github.com/lbryio/lbcd/version"
	btcutil "github.com/lbryio/lbcutil"
	"github.com/lbryio/lbcwallet/internal/cfgutil"
	"github.com/lbryio/lbcwallet/netparams"
	"github.com/lbryio/lbcwallet/wallet"
)

const (
	defaultCAFilename       = "lbcd.cert"
	defaultConfigFilename   = "lbcwallet.conf"
	defaultLogLevel         = "info"
	defaultLogDirname       = "logs"
	defaultLogFilename      = "lbcwallet.log"
	defaultRPCMaxClients    = 10
	defaultRPCMaxWebsockets = 25
)

var (
	lbcdDefaultCAFile  = filepath.Join(btcutil.AppDataDir("lbcd", false), "rpc.cert")
	defaultAppDataDir  = btcutil.AppDataDir("lbcwallet", false)
	defaultConfigFile  = filepath.Join(defaultAppDataDir, defaultConfigFilename)
	defaultRPCKeyFile  = filepath.Join(defaultAppDataDir, "rpc.key")
	defaultRPCCertFile = filepath.Join(defaultAppDataDir, "rpc.cert")
	defaultLogDir      = filepath.Join(defaultAppDataDir, defaultLogDirname)
)

type config struct {
	// General application behavior
	ConfigFile  *cfgutil.ExplicitString `short:"C" long:"configfile" description:"Path to configuration file"`
	ShowVersion bool                    `short:"V" long:"version" description:"Display version information and exit"`
	Create      bool                    `long:"create" description:"Create the wallet if it does not exist"`
	CreateTemp  bool                    `long:"createtemp" description:"Create a temporary simulation wallet (pass=password) in the data directory indicated; must call with --datadir"`
	AppDataDir  *cfgutil.ExplicitString `short:"A" long:"appdata" description:"Application data directory for wallet config, databases and logs"`
	TestNet3    bool                    `long:"testnet" description:"Use the test Bitcoin network (version 3) (default client port: 19244, server port: 19245)"`
	Regtest     bool                    `long:"regtest" description:"Use the regression test network (default client port: 29244, server port: 29245)"`
	DebugLevel  string                  `short:"d" long:"debuglevel" description:"Logging level {trace, debug, info, warn, error, critical}"`
	LogDir      string                  `long:"logdir" description:"Directory to log output."`
	Profile     string                  `long:"profile" description:"Enable HTTP profiling on given port -- NOTE port must be between 1024 and 65536"`
	DBTimeout   time.Duration           `long:"dbtimeout" description:"The timeout value to use when opening the wallet database."`

	// Wallet options
	WalletPass string `long:"walletpass" default-mask:"-" description:"The public wallet password -- Only required if the wallet was created with one"`

	// RPC client options
	RPCConnect       string                  `short:"c" long:"rpcconnect" description:"Hostname/IP and port of lbcd RPC server to connect to (default localhost:9245, testnet: localhost:19245, regtest: localhost:29245)"`
	CAFile           *cfgutil.ExplicitString `long:"cafile" description:"File containing root certificates to authenticate a TLS connections with lbcd"`
	DisableClientTLS bool                    `long:"noclienttls" description:"Disable TLS for the RPC client"`
	SkipVerify       bool                    `long:"skipverify" description:"Skip verifying TLS for the RPC client"`
	Proxy            string                  `long:"proxy" description:"Connect via SOCKS5 proxy (eg. 127.0.0.1:9050)"`
	ProxyUser        string                  `long:"proxyuser" description:"Username for proxy server"`
	ProxyPass        string                  `long:"proxypass" default-mask:"-" description:"Password for proxy server"`

	// RPC server options
	RPCCert                *cfgutil.ExplicitString `long:"rpccert" description:"File containing the certificate file"`
	RPCKey                 *cfgutil.ExplicitString `long:"rpckey" description:"File containing the certificate key"`
	OneTimeTLSKey          bool                    `long:"onetimetlskey" description:"Generate a new TLS certpair at startup, but only write the certificate to disk"`
	DisableServerTLS       bool                    `long:"noservertls" description:"Disable TLS for the RPC server"`
	LegacyRPCListeners     []string                `long:"rpclisten" description:"Listen for legacy RPC connections on this interface/port (default port: 9244, testnet: 19244, regtest: 29244)"`
	LegacyRPCMaxClients    int64                   `long:"rpcmaxclients" description:"Max number of legacy RPC clients for standard connections"`
	LegacyRPCMaxWebsockets int64                   `long:"rpcmaxwebsockets" description:"Max number of RPC websocket connections"`
	RPCUser                string                  `short:"u" long:"rpcuser" description:"Username for RPC and lbcd authentication"`
	RPCPass                string                  `short:"P" long:"rpcpass" default-mask:"-" description:"Password for RPC and lbcd authentication"`

	// Deprecated options
	DataDir *cfgutil.ExplicitString `short:"b" long:"datadir" default-mask:"-" description:"DEPRECATED -- use appdata instead"`
}

// cleanAndExpandPath expands environement variables and leading ~ in the
// passed path, cleans the result, and returns it.
func cleanAndExpandPath(path string) string {
	// NOTE: The os.ExpandEnv doesn't work with Windows cmd.exe-style
	// %VARIABLE%, but they variables can still be expanded via POSIX-style
	// $VARIABLE.
	path = os.ExpandEnv(path)

	if !strings.HasPrefix(path, "~") {
		return filepath.Clean(path)
	}

	// Expand initial ~ to the current user's home directory, or ~otheruser
	// to otheruser's home directory.  On Windows, both forward and backward
	// slashes can be used.
	path = path[1:]

	var pathSeparators string
	if runtime.GOOS == "windows" {
		pathSeparators = string(os.PathSeparator) + "/"
	} else {
		pathSeparators = string(os.PathSeparator)
	}

	userName := ""
	if i := strings.IndexAny(path, pathSeparators); i != -1 {
		userName = path[:i]
		path = path[i:]
	}

	homeDir := ""
	var u *user.User
	var err error
	if userName == "" {
		u, err = user.Current()
	} else {
		u, err = user.Lookup(userName)
	}
	if err == nil {
		homeDir = u.HomeDir
	}
	// Fallback to CWD if user lookup fails or user has no home directory.
	if homeDir == "" {
		homeDir = "."
	}

	return filepath.Join(homeDir, path)
}

// validLogLevel returns whether or not logLevel is a valid debug log level.
func validLogLevel(logLevel string) bool {
	switch logLevel {
	case "trace":
		fallthrough
	case "debug":
		fallthrough
	case "info":
		fallthrough
	case "warn":
		fallthrough
	case "error":
		fallthrough
	case "critical":
		return true
	}
	return false
}

// supportedSubsystems returns a sorted slice of the supported subsystems for
// logging purposes.
func supportedSubsystems() []string {
	// Convert the subsystemLoggers map keys to a slice.
	subsystems := make([]string, 0, len(subsystemLoggers))
	for subsysID := range subsystemLoggers {
		subsystems = append(subsystems, subsysID)
	}

	// Sort the subsytems for stable display.
	sort.Strings(subsystems)
	return subsystems
}

// parseAndSetDebugLevels attempts to parse the specified debug level and set
// the levels accordingly.  An appropriate error is returned if anything is
// invalid.
func parseAndSetDebugLevels(debugLevel string) error {
	// When the specified string doesn't have any delimters, treat it as
	// the log level for all subsystems.
	if !strings.Contains(debugLevel, ",") && !strings.Contains(debugLevel, "=") {
		// Validate debug log level.
		if !validLogLevel(debugLevel) {
			str := "the specified debug level [%v] is invalid"
			return fmt.Errorf(str, debugLevel)
		}

		// Change the logging level for all subsystems.
		setLogLevels(debugLevel)

		return nil
	}

	// Split the specified string into subsystem/level pairs while detecting
	// issues and update the log levels accordingly.
	for _, logLevelPair := range strings.Split(debugLevel, ",") {
		if !strings.Contains(logLevelPair, "=") {
			str := "the specified debug level contains an invalid " +
				"subsystem/level pair [%v]"
			return fmt.Errorf(str, logLevelPair)
		}

		// Extract the specified subsystem and log level.
		fields := strings.Split(logLevelPair, "=")
		subsysID, logLevel := fields[0], fields[1]

		// Validate subsystem.
		if _, exists := subsystemLoggers[subsysID]; !exists {
			str := "the specified subsystem [%v] is invalid -- " +
				"supported subsytems %v"
			return fmt.Errorf(str, subsysID, supportedSubsystems())
		}

		// Validate log level.
		if !validLogLevel(logLevel) {
			str := "the specified debug level [%v] is invalid"
			return fmt.Errorf(str, logLevel)
		}

		setLogLevel(subsysID, logLevel)
	}

	return nil
}

// loadConfig initializes and parses the config using a config file and command
// line options.
//
// The configuration proceeds as follows:
//  1. Start with a default config with sane settings
//  2. Pre-parse the command line to check for an alternative config file
//  3. Load configuration file overwriting defaults with any specified options
//  4. Parse CLI options and overwrite/add any specified options
//
// The above results in lbcwallet functioning properly without any config
// settings while still allowing the user to override settings with config files
// and command line options.  Command line options always take precedence.
func loadConfig() (*config, []string, error) {
	// Default config.
	cfg := config{
		DebugLevel:             defaultLogLevel,
		ConfigFile:             cfgutil.NewExplicitString(defaultConfigFile),
		AppDataDir:             cfgutil.NewExplicitString(defaultAppDataDir),
		LogDir:                 defaultLogDir,
		CAFile:                 cfgutil.NewExplicitString(""),
		RPCKey:                 cfgutil.NewExplicitString(defaultRPCKeyFile),
		RPCCert:                cfgutil.NewExplicitString(defaultRPCCertFile),
		LegacyRPCMaxClients:    defaultRPCMaxClients,
		LegacyRPCMaxWebsockets: defaultRPCMaxWebsockets,
		DataDir:                cfgutil.NewExplicitString(defaultAppDataDir),
		DBTimeout:              wallet.DefaultDBTimeout,
	}

	// Pre-parse the command line options to see if an alternative config
	// file or the version flag was specified.
	preCfg := cfg
	preParser := flags.NewParser(&preCfg, flags.Default)
	_, err := preParser.Parse()
	if err != nil {
		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
			preParser.WriteHelp(os.Stderr)
		}
		return nil, nil, err
	}

	// Show the version and exit if the version flag was specified.
	funcName := "loadConfig"
	appName := filepath.Base(os.Args[0])
	appName = strings.TrimSuffix(appName, filepath.Ext(appName))
	usageMessage := fmt.Sprintf("Use %s -h to show usage", appName)
	if preCfg.ShowVersion {
		fmt.Println(appName, "version", version.Full())
		os.Exit(0)
	}

	// Load additional config from file.
	var configFileError error
	parser := flags.NewParser(&cfg, flags.Default)
	configFilePath := preCfg.ConfigFile.Value
	if preCfg.ConfigFile.ExplicitlySet() {
		configFilePath = cleanAndExpandPath(configFilePath)
	} else {
		appDataDir := preCfg.AppDataDir.Value
		if !preCfg.AppDataDir.ExplicitlySet() && preCfg.DataDir.ExplicitlySet() {
			appDataDir = cleanAndExpandPath(preCfg.DataDir.Value)
		}
		if appDataDir != defaultAppDataDir {
			configFilePath = filepath.Join(appDataDir, defaultConfigFilename)
		}
	}
	err = flags.NewIniParser(parser).ParseFile(configFilePath)
	if err != nil {
		if _, ok := err.(*os.PathError); !ok {
			fmt.Fprintln(os.Stderr, err)
			parser.WriteHelp(os.Stderr)
			return nil, nil, err
		}
		configFileError = err
	}

	// Parse command line options again to ensure they take precedence.
	remainingArgs, err := parser.Parse()
	if err != nil {
		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
			parser.WriteHelp(os.Stderr)
		}
		return nil, nil, err
	}

	// Check deprecated aliases.  The new options receive priority when both
	// are changed from the default.
	if cfg.DataDir.ExplicitlySet() {
		fmt.Fprintln(os.Stderr, "datadir option has been replaced by "+
			"appdata -- please update your config")
		if !cfg.AppDataDir.ExplicitlySet() {
			cfg.AppDataDir.Value = cfg.DataDir.Value
		}
	}

	// If an alternate data directory was specified, and paths with defaults
	// relative to the data dir are unchanged, modify each path to be
	// relative to the new data dir.
	if cfg.AppDataDir.ExplicitlySet() {
		cfg.AppDataDir.Value = cleanAndExpandPath(cfg.AppDataDir.Value)
		if !cfg.RPCKey.ExplicitlySet() {
			cfg.RPCKey.Value = filepath.Join(cfg.AppDataDir.Value, "rpc.key")
		}
		if !cfg.RPCCert.ExplicitlySet() {
			cfg.RPCCert.Value = filepath.Join(cfg.AppDataDir.Value, "rpc.cert")
		}
	}

	// Choose the active network params based on the selected network.
	// Multiple networks can't be selected simultaneously.
	numNets := 0
	if cfg.TestNet3 {
		activeNet = &netparams.TestNet3Params
		numNets++
	}
	if cfg.Regtest {
		activeNet = &netparams.RegTestParams
		numNets++
	}
	if numNets > 1 {
		str := "%s: more than one networks has been specified"
		err := fmt.Errorf(str, "loadConfig")
		fmt.Fprintln(os.Stderr, err)
		parser.WriteHelp(os.Stderr)
		return nil, nil, err
	}

	// Append the network type to the log directory so it is "namespaced"
	// per network.
	cfg.LogDir = cleanAndExpandPath(cfg.LogDir)
	cfg.LogDir = filepath.Join(cfg.LogDir, activeNet.Params.Name)

	// Special show command to list supported subsystems and exit.
	if cfg.DebugLevel == "show" {
		fmt.Println("Supported subsystems", supportedSubsystems())
		os.Exit(0)
	}

	// Initialize log rotation.  After log rotation has been initialized, the
	// logger variables may be used.
	initLogRotator(filepath.Join(cfg.LogDir, defaultLogFilename))

	// Parse, validate, and set debug log level(s).
	if err := parseAndSetDebugLevels(cfg.DebugLevel); err != nil {
		err := fmt.Errorf("%s: %v", "loadConfig", err.Error())
		fmt.Fprintln(os.Stderr, err)
		parser.WriteHelp(os.Stderr)
		return nil, nil, err
	}

	if cfg.CreateTemp {
		errMsg := "Tried to create a temporary simulation wallet"
		// Exit if you try to use a simulation wallet with a standard
		// data directory.
		if !(cfg.AppDataDir.ExplicitlySet() || cfg.DataDir.ExplicitlySet()) {
			errMsg += ", but failed to specify data directory!"
			fmt.Fprintln(os.Stderr, errMsg)
			os.Exit(0)
		}

		// Exit if you try to use a simulation wallet on anything other than
		// regtest or testnet3.
		if !(cfg.Regtest || cfg.TestNet3) {
			errMsg += "for network other than regtest, or testnet3"
			fmt.Fprintln(os.Stderr, errMsg)
			os.Exit(0)
		}
	}

	// Ensure the wallet exists or create it when the create flag is set.
	netDir := networkDir(cfg.AppDataDir.Value, activeNet.Params)
	dbPath := filepath.Join(netDir, wallet.WalletDBName)

	if cfg.CreateTemp && cfg.Create {
		err := fmt.Errorf("the flags --create and --createtemp can not " +
			"be specified together. Use --help for more information")
		fmt.Fprintln(os.Stderr, err)
		return nil, nil, err
	}

	dbFileExists, err := cfgutil.FileExists(dbPath)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		return nil, nil, err
	}

	if cfg.CreateTemp { // nolint:gocritic
		tempWalletExists := false

		if dbFileExists {
			str := fmt.Sprintf("The wallet already exists. Loading this " +
				"wallet instead.")
			fmt.Fprintln(os.Stdout, str)
			tempWalletExists = true
		}

		// Ensure the data directory for the network exists.
		if err := checkCreateDir(netDir); err != nil {
			fmt.Fprintln(os.Stderr, err)
			return nil, nil, err
		}

		if !tempWalletExists {
			// Perform the initial wallet creation wizard.
			if err := createSimulationWallet(&cfg); err != nil {
				fmt.Fprintln(os.Stderr, "Unable to create wallet:", err)
				return nil, nil, err
			}
		}
	} else if cfg.Create {
		// Error if the create flag is set and the wallet already
		// exists.
		if dbFileExists {
			err := fmt.Errorf("the wallet database file `%v` "+
				"already exists", dbPath)
			fmt.Fprintln(os.Stderr, err)
			return nil, nil, err
		}

		// Ensure the data directory for the network exists.
		if err := checkCreateDir(netDir); err != nil {
			fmt.Fprintln(os.Stderr, err)
			return nil, nil, err
		}

		// Perform the initial wallet creation wizard.
		if err := createWallet(&cfg); err != nil {
			fmt.Fprintln(os.Stderr, "Unable to create wallet:", err)
			return nil, nil, err
		}

		// Created successfully, so exit now with success.
		os.Exit(0)
	}

	localhostListeners := map[string]struct{}{
		"localhost": {},
		"127.0.0.1": {},
		"::1":       {},
	}

	if cfg.RPCConnect == "" {
		cfg.RPCConnect = net.JoinHostPort("localhost", activeNet.RPCClientPort)
	}

	// Add default port to connect flag if missing.
	cfg.RPCConnect, err = cfgutil.NormalizeAddress(cfg.RPCConnect,
		activeNet.RPCClientPort)
	if err != nil {
		fmt.Fprintf(os.Stderr,
			"Invalid rpcconnect network address: %v\n", err)
		return nil, nil, err
	}

	RPCHost, _, err := net.SplitHostPort(cfg.RPCConnect)
	if err != nil {
		return nil, nil, err
	}
	if !cfg.DisableClientTLS {
		// If CAFile is unset, choose either the copy or local lbcd cert.
		if !cfg.CAFile.ExplicitlySet() {
			cfg.CAFile.Value = filepath.Join(cfg.AppDataDir.Value, defaultCAFilename)

			// If the CA copy does not exist, check if we're connecting to
			// a local lbcd and switch to its RPC cert if it exists.
			certExists, err := cfgutil.FileExists(cfg.CAFile.Value)
			if err != nil {
				fmt.Fprintln(os.Stderr, err)
				return nil, nil, err
			}
			if !certExists {
				if _, ok := localhostListeners[RPCHost]; ok {
					lbcdCertExists, err := cfgutil.FileExists(
						lbcdDefaultCAFile)
					if err != nil {
						fmt.Fprintln(os.Stderr, err)
						return nil, nil, err
					}
					if lbcdCertExists {
						cfg.CAFile.Value = lbcdDefaultCAFile
					}
				}
			}
		}
	}

	if len(cfg.LegacyRPCListeners) == 0 {
		addrs, err := net.LookupHost("localhost")
		if err != nil {
			return nil, nil, err
		}
		cfg.LegacyRPCListeners = make([]string, 0, len(addrs))
		for _, addr := range addrs {
			addr = net.JoinHostPort(addr, activeNet.RPCServerPort)
			cfg.LegacyRPCListeners = append(cfg.LegacyRPCListeners, addr)
		}
	}

	// Add default port to all rpc listener addresses if needed and remove
	// duplicate addresses.
	cfg.LegacyRPCListeners, err = cfgutil.NormalizeAddresses(
		cfg.LegacyRPCListeners, activeNet.RPCServerPort)
	if err != nil {
		fmt.Fprintf(os.Stderr,
			"Invalid network address in legacy RPC listeners: %v\n", err)
		return nil, nil, err
	}

	if cfg.DisableServerTLS {
		for _, addr := range cfg.LegacyRPCListeners {
			_, _, err := net.SplitHostPort(addr)
			if err != nil {
				str := "%s: RPC listen interface '%s' is " +
					"invalid: %v"
				err := fmt.Errorf(str, funcName, addr, err)
				fmt.Fprintln(os.Stderr, err)
				fmt.Fprintln(os.Stderr, usageMessage)
				return nil, nil, err
			}
		}
	}

	// Expand environment variable and leading ~ for filepaths.
	cfg.CAFile.Value = cleanAndExpandPath(cfg.CAFile.Value)
	cfg.RPCCert.Value = cleanAndExpandPath(cfg.RPCCert.Value)
	cfg.RPCKey.Value = cleanAndExpandPath(cfg.RPCKey.Value)

	// Warn about missing config file after the final command line parse
	// succeeds.  This prevents the warning on help messages and invalid
	// options.
	if configFileError != nil {
		log.Warnf("%v", configFileError)
	}

	return &cfg, remainingArgs, nil
}