/*
goredo -- redo implementation on pure Go
Copyright (C) 2020 Sergey Matveev <stargrave@stargrave.org>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

// Logging facilities

package main

import (
	"bytes"
	"flag"
	"fmt"
	"os"
	"strings"
	"sync"

	"golang.org/x/term"
)

const (
	EnvLevel   = "REDO_LEVEL"
	EnvDebug   = "REDO_DEBUG"
	EnvLogWait = "REDO_LOG_WAIT"
	EnvLogLock = "REDO_LOG_LOCK"
	EnvLogPid  = "REDO_LOG_PID"
	EnvLogJS   = "REDO_LOG_JS"
	EnvNoColor = "NO_COLOR"
)

var (
	Level   = 0
	NoColor bool
	Debug   bool
	LogWait bool
	LogLock bool
	LogJS   bool
	MyPid   int

	CDebug string
	CRedo  string
	CWait  string
	CLock  string
	CErr   string
	CWarn  string
	CJS    string
	CReset string
	CNone  string = "NONE"

	flagDebug   = flag.Bool("debug", false, fmt.Sprintf("enable debug logging (%s=1)", EnvDebug))
	flagLogWait = flag.Bool("log-wait", false, fmt.Sprintf("enable wait messages logging (%s=1)", EnvLogWait))
	flagLogLock = flag.Bool("log-lock", false, fmt.Sprintf("enable lock messages logging (%s=1)", EnvLogLock))
	flagLogPid  = flag.Bool("log-pid", false, fmt.Sprintf("append PIDs (%s=1)", EnvLogPid))
	flagLogJS   = flag.Bool("log-js", false, fmt.Sprintf("enable jobserver messages logging (%s=1)", EnvLogJS))

	LogMutex   sync.Mutex
	LogLenPrev int
)

func init() {
	var b bytes.Buffer
	t := term.NewTerminal(&b, "")
	CDebug = string(t.Escape.Yellow)
	CRedo = string(t.Escape.Green)
	CWait = string(t.Escape.Blue)
	CLock = string(t.Escape.Cyan)
	CErr = string(t.Escape.Red)
	CWarn = string(t.Escape.Magenta)
	CJS = string(t.Escape.White)
	CReset = string(t.Escape.Reset)
}

func fillUpToTermSize(s, end string) string {
	sLen := len(s)
	if sLen < LogLenPrev {
		s += strings.Repeat(" ", LogLenPrev-sLen)
		LogLenPrev = sLen
	} else {
		LogLenPrev = sLen
	}
	return s + end
}

func trace(level, format string, args ...interface{}) {
	var p string
	if MyPid != 0 {
		p = fmt.Sprintf("[%d] ", MyPid)
	}
	switch level {
	case CNone:
		LogMutex.Lock()
		os.Stderr.WriteString(fillUpToTermSize(
			StderrPrefix+p+fmt.Sprintf(format, args...), "\n",
		))
		LogMutex.Unlock()
		return
	case CDebug:
		if !Debug {
			return
		}
		p += "dbg  "
	case CWait:
		if !(LogWait || Debug) {
			return
		}
		p += "wait "
	case CRedo:
		p += "redo "
	case CLock:
		if !(LogLock || Debug) {
			return
		}
		p += "lock "
	case CJS:
		if !(LogJS || Debug) {
			return
		}
		p += "js   "
	case CErr:
		p += "err  "
	case CWarn:
		p += "warn "
	}
	msg := fmt.Sprintf(format, args...)
	msg = StderrPrefix + colourize(level, p+strings.Repeat(". ", Level)+msg)
	LogMutex.Lock()
	os.Stderr.WriteString(fillUpToTermSize(msg, "\n"))
	LogMutex.Unlock()
}

func colourize(colour, s string) string {
	if NoColor {
		return s
	}
	return colour + s + CReset
}