package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/fsnotify/fsnotify"
	lm "github.com/hrfee/jfa-go/logmessages"
	pollingWatcher "github.com/radovskyb/watcher"
)

const (
	RetryCount    = 2
	RetryInterval = time.Second
)

// GenInternalReset generates a local password reset PIN, for use with the PWR option on the Admin page.
func (app *appContext) GenInternalReset(userID string) (InternalPWR, error) {
	pin := genAuthToken()
	user, err := app.jf.UserByID(userID, false)
	if err != nil {
		return InternalPWR{}, err
	}
	pwr := InternalPWR{
		PIN:      pin,
		Username: user.Name,
		ID:       userID,
		Expiry:   time.Now().Add(30 * time.Minute),
	}
	return pwr, nil
}

// GenResetLink generates and returns a password reset link.
func GenResetLink(pin string) (string, error) {
	url := ExternalURI(nil)
	var pinLink string
	if url == "" {
		return pinLink, errors.New(lm.NoExternalHost)
	}
	// Strip /invite from end of this URL, ik it's ugly.
	pinLink = fmt.Sprintf("%s/reset?pin=%s", url, pin)
	return pinLink, nil
}

func (app *appContext) StartPWR() {
	app.info.Printf(lm.StartDaemon, "PWR")
	path := app.config.Section("password_resets").Key("watch_directory").String()
	if _, err := os.Stat(path); os.IsNotExist(err) {
		app.err.Printf(lm.FailedStartDaemon, "PWR", fmt.Sprintf(lm.PathNotFound, path))
		return
	}

	usePolling := app.config.Section("password_resets").Key("watch_polling").MustBool(false)

	if !messagesEnabled {
		return
	}
	if usePolling {
		watcher := pollingWatcher.New()
		watcher.FilterOps(pollingWatcher.Write)

		go monitorPolling(app, watcher)
		if err := watcher.Add(path); err != nil {
			app.err.Printf(lm.FailedStartDaemon, "PWR (polling)", err)
		}
		if err := watcher.Start(time.Second * 5); err != nil {
			app.err.Printf(lm.FailedStartDaemon, "PWR (polling)", err)
		}
	} else {
		watcher, err := fsnotify.NewWatcher()
		if err != nil {
			app.err.Printf(lm.FailedStartDaemon, "PWR", err)
			return
		}
		defer watcher.Close()

		go monitorFS(app, watcher)
		err = watcher.Add(path)
		if err != nil {
			app.err.Printf(lm.FailedStartDaemon, "PWR", err)
		}
	}

	waitForRestart()
}

// PasswordReset represents a passwordreset-xyz.json file generated by Jellyfin.
type PasswordReset struct {
	Pin      string    `json:"Pin"`
	Username string    `json:"UserName"`
	Expiry   time.Time `json:"ExpirationDate"`
	Internal bool      `json:"Internal,omitempty"`
}

func validatePWR(app *appContext, fname string, attempt int) {
	currentTime := time.Now()
	if !strings.Contains(fname, "passwordreset") {
		return
	}
	var pwr PasswordReset
	data, err := os.ReadFile(fname)
	if err != nil {
		app.debug.Printf(lm.FailedReading, fname, err)
		return
	}
	err = json.Unmarshal(data, &pwr)
	if len(pwr.Pin) == 0 || err != nil {
		app.debug.Printf(lm.FailedReading, fname, err)
		return
	}
	app.info.Printf(lm.NewPWRForUser, pwr.Username)
	if pwr.Expiry.Before(currentTime) {
		app.err.Printf(lm.PWRExpired, pwr.Username, pwr.Expiry)
		return
	}
	user, err := app.jf.UserByName(pwr.Username, false)
	if err != nil || user.ID == "" {
		app.err.Printf(lm.FailedGetUser, pwr.Username, lm.Jellyfin, err)
		return
	}
	name := app.getAddressOrName(user.ID)
	if name != "" {
		msg, err := app.email.constructReset(pwr, false)

		if err != nil {
			app.err.Printf(lm.FailedConstructPWRMessage, pwr.Username, err)
		} else if err := app.sendByID(msg, user.ID); err != nil {
			app.err.Printf(lm.FailedSendPWRMessage, pwr.Username, name, err)
		} else {
			app.err.Printf(lm.SentPWRMessage, pwr.Username, name)
		}
	}
}

func monitorFS(app *appContext, watcher *fsnotify.Watcher) {
	for {
		select {
		case event, ok := <-watcher.Events:
			if !ok {
				return
			}
			if event.Has(fsnotify.Write) {
				validatePWR(app, event.Name, 0)
			}
		case err, ok := <-watcher.Errors:
			if !ok {
				return
			}
			app.err.Printf(lm.FailedStartDaemon, "PWR", err)
		}
	}
}

func monitorPolling(app *appContext, watcher *pollingWatcher.Watcher) {
	for {
		select {
		case event := <-watcher.Event:
			validatePWR(app, event.Path, 0)
		case err := <-watcher.Error:
			app.err.Printf(lm.FailedStartDaemon, "PWR (polling)", err)
			return
		case <-watcher.Closed:
			return
		}
	}
}