/*
 * 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 (
	"fmt"
	"os"

	"github.com/conformal/btclog"
	"github.com/conformal/btcwallet/chain"
	"github.com/conformal/btcwallet/txstore"
	"github.com/conformal/seelog"
)

const (
	// lockTimeThreshold is the number below which a lock time is
	// interpreted to be a block number.  Since an average of one block
	// is generated per 10 minutes, this allows blocks for about 9,512
	// years.  However, if the field is interpreted as a timestamp, given
	// the lock time is a uint32, the max is sometime around 2106.
	lockTimeThreshold uint32 = 5e8 // Tue Nov 5 00:53:20 1985 UTC
)

// Loggers per subsytem.  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
	log        = btclog.Disabled
	txstLog    = btclog.Disabled
	chainLog   = btclog.Disabled
)

// subsystemLoggers maps each subsystem identifier to its associated logger.
var subsystemLoggers = map[string]btclog.Logger{
	"BTCW": log,
	"TXST": txstLog,
	"CHNS": chainLog,
}

// 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 "BTCW":
		log = logger
	case "TXST":
		txstLog = logger
		txstore.UseLogger(logger)
	case "CHNS":
		chainLog = logger
		chain.UseLogger(logger)
	}
}

// initSeelogLogger initializes a new seelog logger that is used as the backend
// for all logging subsytems.
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)
	}
}

// pickNoun returns the singular or plural form of a noun depending
// on the count n.
func pickNoun(n int, singular, plural string) string {
	if n == 1 {
		return singular
	}
	return plural
}