/*
goredo -- djb's redo implementation on pure Go
Copyright (C) 2020-2021 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/>.
*/

package main

import (
	"crypto/rand"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"path"
	"path/filepath"
	"strconv"

	"go.cypherpunks.ru/recfile"
)

var (
	Cwd       string
	BuildUUID string
)

func mustSetenv(key, value string) {
	if err := os.Setenv(key, value); err != nil {
		panic(err)
	}
}

func mustParseFd(v, name string) *os.File {
	ptr, err := strconv.ParseUint(v, 10, 64)
	if err != nil {
		panic(err)
	}
	fd := os.NewFile(uintptr(ptr), name)
	if fd == nil {
		panic("can not parse fd: " + name)
	}
	return fd
}

func main() {
	version := flag.Bool("version", false, "print version")
	warranty := flag.Bool("warranty", false, "print warranty information")
	symlinks := flag.Bool("symlinks", false, "create necessary symlinks in current directory")

	flag.Usage = usage
	flag.Parse()
	if *warranty {
		fmt.Println(Warranty)
		return
	}
	if *version {
		fmt.Println(versionGet())
		return
	}
	if *symlinks {
		rc := 0
		for _, cmdName := range []string{
			"redo",
			"redo-always",
			"redo-cleanup",
			"redo-dot",
			"redo-ifchange",
			"redo-ifcreate",
			"redo-log",
			"redo-stamp",
			"redo-whichdo",
		} {
			fmt.Println(os.Args[0], "<-", cmdName)
			if err := os.Symlink(os.Args[0], cmdName); err != nil {
				rc = 1
				log.Println(err)
			}
		}
		os.Exit(rc)
	}
	log.SetFlags(0)

	var err error
	Cwd, err = os.Getwd()
	if err != nil {
		log.Fatalln(err)
	}

	NoColor = os.Getenv(EnvNoColor) != ""
	NoSync = os.Getenv(EnvNoSync) == "1"
	InodeTrust = os.Getenv(EnvInodeNoTrust) == ""

	TopDir = os.Getenv(EnvTopDir)
	if TopDir == "" {
		TopDir = "/"
	} else {
		TopDir, err = filepath.Abs(TopDir)
		if err != nil {
			panic(err)
		}
	}
	DirPrefix = os.Getenv(EnvDirPrefix)

	if *flagStderrKeep {
		mustSetenv(EnvStderrKeep, "1")
	}
	if *flagStderrSilent {
		mustSetenv(EnvStderrSilent, "1")
	}
	if *flagNoProgress {
		mustSetenv(EnvNoProgress, "1")
	}
	if *flagDebug {
		mustSetenv(EnvDebug, "1")
	}
	if *flagLogWait {
		mustSetenv(EnvLogWait, "1")
	}
	if *flagLogLock {
		mustSetenv(EnvLogLock, "1")
	}
	if *flagLogPid {
		mustSetenv(EnvLogPid, "1")
	}
	if *flagLogJS {
		mustSetenv(EnvLogJS, "1")
	}
	StderrKeep = os.Getenv(EnvStderrKeep) == "1"
	StderrSilent = os.Getenv(EnvStderrSilent) == "1"
	NoProgress = os.Getenv(EnvNoProgress) == "1"
	Debug = os.Getenv(EnvDebug) == "1"
	LogWait = os.Getenv(EnvLogWait) == "1"
	LogLock = os.Getenv(EnvLogLock) == "1"
	LogJS = os.Getenv(EnvLogJS) == "1"
	if Debug || os.Getenv(EnvLogPid) == "1" {
		MyPid = os.Getpid()
	}
	var traced bool
	if *flagTraceAll {
		mustSetenv(EnvTrace, "1")
	}
	if *flagTrace {
		traced = true
	} else {
		traced = os.Getenv(EnvTrace) == "1"
	}

	// Those are internal envs
	StderrPrefix = os.Getenv(EnvStderrPrefix)
	if v := os.Getenv(EnvLevel); v != "" {
		Level, err = strconv.Atoi(v)
		if err != nil {
			panic(err)
		}
		if Level < 0 {
			panic("negative " + EnvLevel)
		}
	}
	var fdDep *os.File
	if v := os.Getenv(EnvDepFd); v != "" {
		fdDep = mustParseFd(v, EnvDepFd)
	}
	BuildUUID = os.Getenv(EnvBuildUUID)
	tgts := flag.Args()
	if BuildUUID == "" {
		raw := new([16]byte)
		if _, err = io.ReadFull(rand.Reader, raw[:]); err != nil {
			log.Fatalln(err)
		}
		raw[6] = (raw[6] & 0x0F) | uint8(4<<4) // version 4
		BuildUUID = fmt.Sprintf(
			"%x-%x-%x-%x-%x",
			raw[0:4], raw[4:6], raw[6:8], raw[8:10], raw[10:],
		)
		if len(tgts) == 0 {
			tgts = []string{"all"}
		}
	}
	statusInit()

	for i, tgt := range tgts {
		if path.IsAbs(tgt) {
			tgts[i] = cwdMustRel(tgt)
		}
	}

	ok := true
	err = nil
	cmdName := path.Base(os.Args[0])
	trace(
		CDebug, "[%s] run: %s %s cwd:%s dirprefix:%s",
		BuildUUID, cmdName, tgts, Cwd, DirPrefix,
	)

CmdSwitch:
	switch cmdName {
	case "redo":
		for _, tgt := range tgts {
			ok, err = ifchange([]string{tgt}, true, traced)
			if err != nil || !ok {
				break
			}
		}
	case "redo-ifchange":
		ok, err = ifchange(tgts, false, traced)
		if err == nil {
			err = writeDeps(fdDep, tgts)
		}
	case "redo-ifcreate":
		if fdDep == nil {
			log.Fatalln("no", EnvDepFd)
		}
		for _, tgt := range tgts {
			err = ifcreate(fdDep, tgt)
			if err != nil {
				break
			}
		}
	case "redo-always":
		if fdDep == nil {
			log.Fatalln("no", EnvDepFd)
		}
		err = always(fdDep)
	case "redo-cleanup":
		for _, what := range tgts {
			err = cleanupWalker(Cwd, what)
			if err != nil {
				break
			}
		}
	case "redo-dot":
		err = dotPrint(tgts)
	case "redo-stamp":
		if fdDep == nil {
			log.Fatalln("no", EnvDepFd)
		}
		err = stamp(fdDep, os.Stdin)
	case "redo-log":
		if len(tgts) != 1 {
			log.Fatalln("single target expected")
		}
		d, t := cwdAndTgt(tgts[0])
		var fd *os.File
		fd, err = os.Open(path.Join(d, RedoDir, t+LogSuffix))
		if err != nil {
			break
		}
		_, err = io.Copy(os.Stdout, fd)
	case "redo-whichdo":
		if len(tgts) != 1 {
			log.Fatalln("single target expected")
		}
		var fdTmp *os.File
		fdTmp, err = ioutil.TempFile("", "")
		if err != nil {
			break
		}
		os.Remove(fdTmp.Name())
		cwd, tgt := cwdAndTgt(tgts[0])
		doFile, upLevels, err := findDo(fdTmp, cwd, tgt)
		if err != nil {
			break
		}
		_, err = fdTmp.Seek(0, 0)
		if err != nil {
			break
		}
		r := recfile.NewReader(fdTmp)
		for {
			m, err := r.NextMap()
			if err != nil {
				if err == io.EOF {
					break
				}
				break CmdSwitch
			}
			fmt.Println(cwdMustRel(cwd, m["Target"]))
		}
		if doFile == "" {
			ok = false
		} else {
			p := make([]string, 0, upLevels+2)
			p = append(p, cwd)
			for i := 0; i < upLevels; i++ {
				p = append(p, "..")
			}
			p = append(p, doFile)
			rel, err := filepath.Rel(Cwd, path.Join(p...))
			if err != nil {
				panic(err)
			}
			fmt.Println(rel)
		}
	default:
		log.Fatalln("unknown command", cmdName)
	}
	if err != nil {
		log.Println(err)
	}
	rc := 0
	if !ok || err != nil {
		rc = 1
	}
	trace(CDebug, "[%s] finished: %s %s", BuildUUID, cmdName, tgts)
	os.Exit(rc)
}