// Copyright (c) 2013-2016 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"
	"os"

	"github.com/btcsuite/btcd/addrmgr"
	"github.com/btcsuite/btcd/blockchain"
	"github.com/btcsuite/btcd/blockchain/indexers"
	"github.com/btcsuite/btcd/connmgr"
	"github.com/btcsuite/btcd/database"
	"github.com/btcsuite/btcd/mempool"
	"github.com/btcsuite/btcd/peer"
	"github.com/btcsuite/btcd/txscript"
	"github.com/btcsuite/btclog"
	"github.com/btcsuite/seelog"
)

const (
	// maxRejectReasonLen is the maximum length of a sanitized reject reason
	// that will be logged.
	maxRejectReasonLen = 250
)

// Loggers per subsystem.  Note that backendLog is a seelog logger that all of
// the subsystem loggers route their messages to.  When adding new subsystems,
// add a reference here, to the subsystemLoggers map, and the useLogger
// function.
var (
	backendLog = seelog.Disabled
	adxrLog    = btclog.Disabled
	amgrLog    = btclog.Disabled
	cmgrLog    = btclog.Disabled
	bcdbLog    = btclog.Disabled
	bmgrLog    = btclog.Disabled
	btcdLog    = btclog.Disabled
	chanLog    = btclog.Disabled
	discLog    = btclog.Disabled
	indxLog    = btclog.Disabled
	minrLog    = btclog.Disabled
	peerLog    = btclog.Disabled
	rpcsLog    = btclog.Disabled
	scrpLog    = btclog.Disabled
	srvrLog    = btclog.Disabled
	txmpLog    = btclog.Disabled
)

// subsystemLoggers maps each subsystem identifier to its associated logger.
var subsystemLoggers = map[string]btclog.Logger{
	"ADXR": adxrLog,
	"AMGR": amgrLog,
	"CMGR": cmgrLog,
	"BCDB": bcdbLog,
	"BMGR": bmgrLog,
	"BTCD": btcdLog,
	"CHAN": chanLog,
	"DISC": discLog,
	"INDX": indxLog,
	"MINR": minrLog,
	"PEER": peerLog,
	"RPCS": rpcsLog,
	"SCRP": scrpLog,
	"SRVR": srvrLog,
	"TXMP": txmpLog,
}

// logClosure is used to provide a closure over expensive logging operations
// so don't have to be performed when the logging level doesn't warrant it.
type logClosure func() string

// String invokes the underlying function and returns the result.
func (c logClosure) String() string {
	return c()
}

// newLogClosure returns a new closure over a function that returns a string
// which itself provides a Stringer interface so that it can be used with the
// logging system.
func newLogClosure(c func() string) logClosure {
	return logClosure(c)
}

// useLogger updates the logger references for subsystemID to logger.  Invalid
// subsystems are ignored.
func useLogger(subsystemID string, logger btclog.Logger) {
	if _, ok := subsystemLoggers[subsystemID]; !ok {
		return
	}
	subsystemLoggers[subsystemID] = logger

	switch subsystemID {
	case "ADXR":
		adxrLog = logger

	case "AMGR":
		amgrLog = logger
		addrmgr.UseLogger(logger)

	case "CMGR":
		cmgrLog = logger
		connmgr.UseLogger(logger)

	case "BCDB":
		bcdbLog = logger
		database.UseLogger(logger)

	case "BMGR":
		bmgrLog = logger

	case "BTCD":
		btcdLog = logger

	case "CHAN":
		chanLog = logger
		blockchain.UseLogger(logger)

	case "DISC":
		discLog = logger

	case "INDX":
		indxLog = logger
		indexers.UseLogger(logger)

	case "MINR":
		minrLog = logger

	case "PEER":
		peerLog = logger
		peer.UseLogger(logger)

	case "RPCS":
		rpcsLog = logger

	case "SCRP":
		scrpLog = logger
		txscript.UseLogger(logger)

	case "SRVR":
		srvrLog = logger

	case "TXMP":
		txmpLog = logger
		mempool.UseLogger(logger)
	}
}

// initSeelogLogger initializes a new seelog logger that is used as the backend
// for all logging subsystems.
func initSeelogLogger(logFile string) {
	config := `
	<seelog type="adaptive" mininterval="2000000" maxinterval="100000000"
		critmsgcount="500" minlevel="trace">
		<outputs formatid="all">
			<console />
			<rollingfile type="size" filename="%s" maxsize="10485760" maxrolls="3" />
		</outputs>
		<formats>
			<format id="all" format="%%Time %%Date [%%LEV] %%Msg%%n" />
		</formats>
	</seelog>`
	config = fmt.Sprintf(config, logFile)

	logger, err := seelog.LoggerFromConfigAsString(config)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create logger: %v", err)
		os.Exit(1)
	}

	backendLog = logger
}

// setLogLevel sets the logging level for provided subsystem.  Invalid
// subsystems are ignored.  Uninitialized subsystems are dynamically created as
// needed.
func setLogLevel(subsystemID string, logLevel string) {
	// Ignore invalid subsystems.
	logger, ok := subsystemLoggers[subsystemID]
	if !ok {
		return
	}

	// Default to info if the log level is invalid.
	level, ok := btclog.LogLevelFromString(logLevel)
	if !ok {
		level = btclog.InfoLvl
	}

	// Create new logger for the subsystem if needed.
	if logger == btclog.Disabled {
		logger = btclog.NewSubsystemLogger(backendLog, subsystemID+": ")
		useLogger(subsystemID, logger)
	}
	logger.SetLevel(level)
}

// setLogLevels sets the log level for all subsystem loggers to the passed
// level.  It also dynamically creates the subsystem loggers as needed, so it
// can be used to initialize the logging system.
func setLogLevels(logLevel string) {
	// Configure all sub-systems with the new logging level.  Dynamically
	// create loggers as needed.
	for subsystemID := range subsystemLoggers {
		setLogLevel(subsystemID, logLevel)
	}
}

// directionString is a helper function that returns a string that represents
// the direction of a connection (inbound or outbound).
func directionString(inbound bool) string {
	if inbound {
		return "inbound"
	}
	return "outbound"
}