package app

import (
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path"
	"syscall"
	"time"

	"git.blackforestbytes.com/BlackForestBytes/goext/exerr"
	"git.blackforestbytes.com/BlackForestBytes/goext/langext"
	"git.blackforestbytes.com/BlackForestBytes/goext/timeext"
	"mikescher.com/kpsync/assets"
)

type InitSyncResponse string //@enum:type

const (
	InitSyncResponseOkay     InitSyncResponse = "OKAY"
	InitSyncResponseFallback InitSyncResponse = "FALLBACK"
	InitSyncResponseAbort    InitSyncResponse = "ABORT"
)

func (app *Application) initSync() (InitSyncResponse, error) {

	err := os.MkdirAll(app.config.WorkDir, os.ModePerm)
	if err != nil {
		return "", exerr.Wrap(err, "").Build()
	}

	app.dbFile = path.Join(app.config.WorkDir, path.Base(app.config.LocalFallback))
	app.stateFile = path.Join(app.config.WorkDir, "kpsync.state")

	if app.isKeepassRunning() {
		app.LogError("keepassxc is already running!", nil)
		app.showErrorNotification("KeePassSync: Error", "An keepassxc instance is already running!\nPlease close it before starting kpsync.")
		return "", exerr.New(exerr.TypeInternal, "keepassxc is already running").Build()
	}

	state := app.readState()

	needsDownload := true

	if state != nil && fileExists(app.dbFile) {
		localCS, err := app.calcLocalChecksum()
		if err != nil {
			app.LogError("Failed to calculate local database checksum", err)
		} else if localCS == state.Checksum {
			remoteETag, remoteLM, err := app.getRemoteState()
			if err != nil {
				app.LogError("Failed to get remote ETag", err)
			} else if remoteETag == state.ETag {

				app.LogInfo(fmt.Sprintf("Found local database matching remote database - skip initial download"))
				app.LogDebug(fmt.Sprintf("Checksum (cached)     := %s", state.Checksum))
				app.LogDebug(fmt.Sprintf("Checksum (local)      := %s", localCS))
				app.LogDebug(fmt.Sprintf("ETag (cached)         := %s", state.ETag))
				app.LogDebug(fmt.Sprintf("ETag (remote)         := %s", remoteETag))
				app.LogDebug(fmt.Sprintf("LastModified (cached) := %s", state.LastModified.Format(time.RFC3339)))
				app.LogDebug(fmt.Sprintf("LastModified (remote) := %s", remoteLM.Format(time.RFC3339)))
				app.LogLine()
				needsDownload = false

			}
		}
	}

	if needsDownload {
		err = func() error {
			fin := app.setTrayState("Downloading database", assets.IconDownload)
			defer fin()

			app.LogInfo(fmt.Sprintf("Downloading remote database to %s", app.dbFile))

			etag, lm, sha, sz, err := app.downloadDatabase()
			if err != nil {
				app.LogError("Failed to download remote database", err)
				return exerr.Wrap(err, "Failed to download remote database").Build()
			}

			app.LogInfo(fmt.Sprintf("Downloaded remote database to %s", app.dbFile))
			app.LogInfo(fmt.Sprintf("Checksum     := %s", sha))
			app.LogInfo(fmt.Sprintf("ETag         := %s", etag))
			app.LogInfo(fmt.Sprintf("Size         := %s (%d)", langext.FormatBytes(sz), sz))
			app.LogInfo(fmt.Sprintf("LastModified := %s", lm.Format(time.RFC3339)))

			err = app.saveState(etag, lm, sha, sz)
			if err != nil {
				app.LogError("Failed to save state", err)
				return exerr.Wrap(err, "Failed to save state").Build()
			}

			app.LogLine()

			return nil
		}()
		if err != nil {

			r, err := app.showChoiceNotification("KeePassSync", "Failed to download remote database.\nUse local fallback?", map[string]string{"y": "Yes", "n": "Abort"})
			if err != nil {
				app.LogError("Failed to show choice notification", err)
				return "", exerr.Wrap(err, "Failed to show choice notification").Build()
			}

			if r == "y" {
				return InitSyncResponseFallback, nil
			} else if r == "n" {
				return InitSyncResponseAbort, nil
			} else {
				return "", exerr.Wrap(err, "").Build()
			}

		}

		return InitSyncResponseOkay, nil

	} else {
		app.LogInfo(fmt.Sprintf("Skip download - use existing local database %s", app.dbFile))
		app.LogLine()

		return InitSyncResponseOkay, nil
	}
}

func (app *Application) runKeepass(fallback bool) {
	app.LogInfo("Starting keepassxc...")

	filePath := app.dbFile
	if fallback {
		filePath = app.config.LocalFallback
	}

	cmd := exec.Command("keepassxc", filePath)

	bgStop := make(chan bool, 128)

	go func() {
		select {
		case <-bgStop:
			return
		case <-app.sigTermKeepassChan:
			app.LogInfo("Received signal to terminate keepassxc")
			if cmd != nil && cmd.Process != nil {
				app.LogInfo(fmt.Sprintf("Terminating keepassxc %d", cmd.Process.Pid))
				err := cmd.Process.Signal(syscall.SIGTERM)
				if errors.Is(err, os.ErrProcessDone) {
					app.LogInfo("keepassxc already terminated")
				} else if err != nil {
					app.LogError("Failed to terminate keepassxc", err)
				} else {
					app.LogInfo("keepassxc terminated successfully")
				}
			} else {
				app.LogInfo("No keepassxc process to terminate")
			}
		}
	}()

	err := cmd.Start()
	if err != nil {
		app.LogError("Failed to start keepassxc", err)
		app.sigErrChan <- exerr.Wrap(err, "Failed to start keepassxc").Build()
		return
	}

	app.LogInfo(fmt.Sprintf("keepassxc started with PID %d", cmd.Process.Pid))
	app.LogLine()

	err = cmd.Wait()

	bgStop <- true

	exitErr := &exec.ExitError{}
	if errors.As(err, &exitErr) {

		app.LogInfo(fmt.Sprintf("keepass exited with code %d", exitErr.ExitCode()))
		app.sigKPExitChan <- true
		return

	}

	if err != nil {
		app.LogError("Failed to run keepassxc", err)
		app.sigErrChan <- exerr.Wrap(err, "Failed to run keepassxc").Build()
		return
	}

	app.LogInfo("keepassxc exited successfully")
	app.LogLine()

	app.sigKPExitChan <- true
	return

}

func (app *Application) onDBFileChanged() {
	app.masterLock.Lock()
	app.uploadRunning.Wait(false)
	app.uploadRunning.Set(true)
	app.masterLock.Unlock()

	defer app.uploadRunning.Set(false)

	fin1 := app.setTrayState("Uploading database", assets.IconUpload)
	defer fin1()

	app.LogInfo("Database file was modified")
	app.LogInfo(fmt.Sprintf("Sleeping for %d ms", app.config.Debounce))

	time.Sleep(timeext.FromMilliseconds(app.config.Debounce))

	state := app.readState()
	localCS, err := app.calcLocalChecksum()
	if err != nil {
		app.LogError("Failed to calculate local database checksum", err)
		app.showErrorNotification("KeePassSync: Error", "Failed to calculate local database checksum")
		return
	}

	if state != nil && localCS == state.Checksum {
		app.LogInfo("Local database still matches remote (via checksum) - no need to upload")
		app.LogInfo(fmt.Sprintf("Checksum (remote/cached) := %s", state.Checksum))
		app.LogInfo(fmt.Sprintf("Checksum (local)         := %s", localCS))
		return
	}

	app.doDBUpload(state, fin1, true)
}

func (app *Application) doDBUpload(state *State, stateClear func(), allowConflictResolution bool) {
	app.LogInfo("Uploading database to remote")

	var eTagPtr *string = nil
	if state != nil {
		eTagPtr = langext.Ptr(state.ETag)
	}

	etag, lm, sha, sz, err := app.uploadDatabase(eTagPtr)
	if errors.Is(err, ETagConflictError) && allowConflictResolution {

		stateClear()
		fin2 := app.setTrayState("Uploading database (conflict", assets.IconUploadConflict)
		defer fin2()

		r, err := app.showChoiceNotification("KeePassSync: Upload failed", "Conflict with remote file.\n[1] Overwrite remote file\n[2] Download remote and sync manually", map[string]string{"o": "Overwrite", "d": "Download", "a": "Abort"})
		if err != nil {
			app.LogError("Failed to show choice notification", err)
			return
		}

		if r == "o" {

			app.LogInfo("Uploading database to remote (unchecked)")

			etag, lm, sha, sz, err := app.uploadDatabase(nil) // unchecked upload
			if err != nil {
				app.LogError("Failed to upload remote database", err)
				app.showErrorNotification("KeePassSync: Error", "Failed to upload remote database")
				return
			}

			app.LogInfo(fmt.Sprintf("Uploaded database to remote"))
			app.LogDebug(fmt.Sprintf("Checksum     := %s", sha))
			app.LogDebug(fmt.Sprintf("ETag         := %s", etag))
			app.LogDebug(fmt.Sprintf("Size         := %s (%d)", langext.FormatBytes(sz), sz))
			app.LogDebug(fmt.Sprintf("LastModified := %s", lm.Format(time.RFC3339)))

			err = app.saveState(etag, lm, sha, sz)
			if err != nil {
				app.LogError("Failed to save state", err)
				app.showErrorNotification("KeePassSync: Error", "Failed to save state")
				return
			}

			app.showSuccessNotification("KeePassSync", "Uploaded database successfully (overwrite remote)")

			app.LogLine()

			return

		} else if r == "d" {

			app.LogInfo(fmt.Sprintf("Re-Downloading remote database to %s", app.dbFile))

			etag, lm, sha, sz, err := app.downloadDatabase()
			if err != nil {
				app.LogError("Failed to download remote database", err)
				return
			}

			app.LogInfo(fmt.Sprintf("Downloaded remote database to %s", app.dbFile))
			app.LogInfo(fmt.Sprintf("Checksum     := %s", sha))
			app.LogInfo(fmt.Sprintf("ETag         := %s", etag))
			app.LogInfo(fmt.Sprintf("Size         := %s (%d)", langext.FormatBytes(sz), sz))
			app.LogInfo(fmt.Sprintf("LastModified := %s", lm.Format(time.RFC3339)))

			err = app.saveState(etag, lm, sha, sz)
			if err != nil {
				app.LogError("Failed to save state", err)
				return
			}

			app.showSuccessNotification("KeePassSync", "Re-Downloaded database successfully")

			app.LogLine()

		} else if r == "a" {

			app.sigManualStopChan <- true
			return

		} else {
			app.LogError("Unknown choice in notification: '"+r+"'", nil)
			app.showErrorNotification("KeePassSync: Error", "Unknown choice in notification: '"+r+"'")
			return
		}

	} else if err != nil {
		app.LogError("Failed to upload remote database", err)
		app.showErrorNotification("KeePassSync: Error", "Failed to upload remote database")
		return
	}

	app.LogInfo(fmt.Sprintf("Uploaded database to remote"))
	app.LogDebug(fmt.Sprintf("Checksum     := %s", sha))
	app.LogDebug(fmt.Sprintf("ETag         := %s", etag))
	app.LogDebug(fmt.Sprintf("Size         := %s (%d)", langext.FormatBytes(sz), sz))
	app.LogDebug(fmt.Sprintf("LastModified := %s", lm.Format(time.RFC3339)))

	err = app.saveState(etag, lm, sha, sz)
	if err != nil {
		app.LogError("Failed to save state", err)
		app.showErrorNotification("KeePassSync: Error", "Failed to save state")
		return
	}

	app.showSuccessNotification("KeePassSync", "Uploaded database successfully")

	app.LogLine()
}

func (app *Application) runFinalSync() {
	app.masterLock.Lock()
	app.uploadRunning.Wait(false)
	app.uploadRunning.Set(true)
	app.masterLock.Unlock()

	defer app.uploadRunning.Set(false)

	fin1 := app.setTrayState("Uploading database", assets.IconUpload)
	defer fin1()

	app.LogInfo("Starting final sync...")

	remoteETag, _, err := app.getRemoteState()
	if err != nil {
		app.LogError("Failed to get remote ETag", err)
	}

	state := app.readState()
	localCS, err := app.calcLocalChecksum()
	if err != nil {
		app.LogError("Failed to calculate local database checksum", err)
		app.showErrorNotification("KeePassSync: Error", "Failed to calculate local database checksum")
		return
	}

	if state != nil && localCS == state.Checksum && remoteETag == state.ETag {
		app.LogInfo("Local database still matches remote (via checksum+etag) - no need to upload")
		app.LogInfo(fmt.Sprintf("Checksum (remote/cached) := %s", state.Checksum))
		app.LogInfo(fmt.Sprintf("Checksum (local)         := %s", localCS))
		app.LogDebug(fmt.Sprintf("ETag (local)            := %s", state.ETag))
		app.LogDebug(fmt.Sprintf("ETag (remote)           := %s", remoteETag))
		return
	}

	app.doDBUpload(state, fin1, false)
}

func (app *Application) runExplicitSync(force bool) {
	app.masterLock.Lock()
	app.uploadRunning.Wait(false)
	app.uploadRunning.Set(true)
	app.masterLock.Unlock()

	defer app.uploadRunning.Set(false)

	state := app.readState()

	if !force {

		remoteETag, _, err := app.getRemoteState()
		if err != nil {
			app.LogError("Failed to get remote ETag", err)
			app.showErrorNotification("KeePassSync: Error", "Failed to get status from remote")
			return
		}

		localCS, err := app.calcLocalChecksum()
		if err != nil {
			app.LogError("Failed to calculate local database checksum", err)
			app.showErrorNotification("KeePassSync: Error", "Failed to calculate local database checksum")
			return
		}

		if state != nil && localCS == state.Checksum {
			app.LogInfo("Local database still matches remote (via checksum+etag) - no need to upload")
			app.LogInfo(fmt.Sprintf("Checksum (remote/cached) := %s", state.Checksum))
			app.LogInfo(fmt.Sprintf("Checksum (local)         := %s", localCS))
			app.LogDebug(fmt.Sprintf("ETag (local)            := %s", state.ETag))
			app.LogDebug(fmt.Sprintf("ETag (remote)           := %s", remoteETag))

			app.showErrorNotification("KeePassSync", "No sync necessary - file is up-to-date with remote")
			return
		}

	}

	app.doDBUpload(state, func() {}, true)
}