package sync

import (
	"os"
	"path/filepath"
	"strings"
	"time"

	"git.csclub.uwaterloo.ca/public/merlin/config"
)

func cscTraceArchLinux(repo *config.Repo, newTime string) []string {
	args := []string{
		"curl",
		"--interface", config.Conf.IPv4Address,
		"-s", repo.TraceHost,
		"-o", newTime,
	}

	return args
}

// return false iff both files exist, are non-empty, and have the same contents
func cscTraceArchLinuxDiff(repo *config.Repo, newTime string) bool {
	readFile := func(file string) string {
		f, err := os.ReadFile(file)
		if err != nil {
			repo.Logger.Debug(err.Error())
			return ""
		}
		return strings.TrimSpace(string(f))
	}

	file1 := readFile(newTime)
	file2 := readFile(filepath.Join(buildDownloadDir(repo), "lastupdate"))

	if file1 == "" || file2 == "" {
		return true
	}
	return file1 != file2
}

// update the lastsync file
func cscTraceArchLinuxUpdate(repo *config.Repo) (args []string) {
	rsyncDir := repo.RsyncDir
	localDir := repo.LocalDir

	repo.RsyncDir = repo.RsyncDir + "/lastsync"
	repo.LocalDir = repo.LocalDir + "/lastsync"

	args = cscSyncArchLinux(repo)

	repo.RsyncDir = rsyncDir
	repo.LocalDir = localDir

	return args
}

func cscTraceDebian(repo *config.Repo, newTime string) []string {
	args := []string{
		"nice", "rsync", "-tv", "-4",
		"--address=" + config.Conf.IPv4Address,
		"--quiet",
		repo.RsyncHost + "::" + filepath.Join(repo.RsyncDir, "project/trace", repo.TraceHost),
		newTime,
	}

	return args
}

// return false iff both files exist and were modified at the same time
func cscTraceDebianDiff(repo *config.Repo, newTime string) bool {
	statFile := func(file string) int64 {
		f, err := os.Stat(file)
		if err != nil {
			repo.Logger.Debug("Error while trying to stat file: " + file)
			return 0
		}

		return f.ModTime().Unix()
	}

	file1 := statFile(newTime)
	file2 := statFile(filepath.Join(buildDownloadDir(repo), "project/trace", repo.TraceHost))

	if file1 == 0 || file2 == 0 {
		return true
	}

	return file1 != file2
}

// update our trace file's modification date by writing the current time
func cscTraceDebianUpdate(repo *config.Repo) {
	target := filepath.Join(buildDownloadDir(repo), "project/trace", config.Conf.Hostname)

	os.MkdirAll(filepath.Join(buildDownloadDir(repo), "project/trace"), 0755)

	f, err := os.OpenFile(target, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
	if err != nil {
		repo.Logger.Error("Unable to open trace file: " + target)
		return
	}
	if _, err = f.WriteString(time.Now().UTC().Format(time.RFC1123)); err != nil {
		repo.Logger.Error("Unable to write to trace file: " + target)
		return
	}
}

// some repos want us to check a last modification time file before performing a full sync
// returns a status to update the original sync's status along with if the sync should continue
func checkIfSyncNeeded(repo *config.Repo) (status int, continueSync bool) {
	// default return values are the default status and to continue the sync
	status = config.FAILURE
	continueSync = true
	if repo.DryRun {
		return
	}
	runCommand := func(args []string) int {
		ch := spawnProcess(repo, args)
		if ch == nil {
			// spawnSyncProcess will have already logged error
			return 1
		}
		cmd := <-ch
		return cmd.ProcessState.ExitCode()
	}

	// create a temp file
	temp, err := os.CreateTemp("/tmp", "merlin-"+repo.Name+"-trace-*")
	if err != nil {
		repo.Logger.Error(err.Error())
		return
	}
	temp.Close()
	defer os.Remove(temp.Name())

	// get the trace command to copy a last updated file
	var args []string
	switch repo.SyncType {
	case "csc-sync-archlinux":
		args = cscTraceArchLinux(repo, temp.Name())
	case "csc-sync-debian":
		args = cscTraceDebian(repo, temp.Name())
	default:
		repo.Logger.Error("Trace files are not implemented for sync type '" + repo.SyncType + "'")
		return
	}

	exit := runCommand(args)
	if exit != 0 {
		// if the process was terminated then don't continue to sync
		if exit == -1 {
			return config.TERMINATED, false
		}
		return
	}

	filesDiffer := true
	switch repo.SyncType {
	case "csc-sync-archlinux":
		filesDiffer = cscTraceArchLinuxDiff(repo, temp.Name())
	case "csc-sync-debian":
		filesDiffer = cscTraceDebianDiff(repo, temp.Name())
	}
	// debian still syncs even if the trace file is the same
	if !filesDiffer && repo.SyncType == "csc-sync-debian" {
		repo.Logger.Error("trace file for " + repo.RsyncHost + " unchanged")
		return
	}
	if filesDiffer {
		// continue sync if files differ
		return
	}

	repo.Logger.Debug("No changes found; full sync will not be made")

	// archlinux wants to sync a "lastsync" file if lastupdate prevents sync
	switch repo.SyncType {
	case "csc-sync-archlinux":
		args = cscTraceArchLinuxUpdate(repo)
	default:
		return config.SUCCESS, false
	}

	exit = runCommand(args)
	if exit != 0 {
		// if the process was terminated then don't continue to sync
		if exit == -1 {
			return config.TERMINATED, false
		}
		return
	}

	return config.SUCCESS, false
}

// csc-sync-debian wants to update a trace file after the repo is done syncing
func postSyncTraceUpdate(repo *config.Repo) {
	if repo.SyncType == "csc-sync-debian" {
		cscTraceDebianUpdate(repo)
	}
}