package scheduler

import (
	"context"
	"time"

	"github.com/robfig/cron/v3"
	"go.uber.org/zap"

	"codeberg.org/mapleopentech/monorepo/cloud/maplepress-backend/config"
	"codeberg.org/mapleopentech/monorepo/cloud/maplepress-backend/pkg/leaderelection"
	siteusecase "codeberg.org/mapleopentech/monorepo/cloud/maplepress-backend/internal/usecase/site"
)

// QuotaResetScheduler handles scheduled usage resets for billing cycles
type QuotaResetScheduler struct {
	cron            *cron.Cron
	resetUsageUC    *siteusecase.ResetMonthlyUsageUseCase
	leaderElection  leaderelection.LeaderElection
	logger          *zap.Logger
	enabled         bool
	schedulePattern string
}

// cronLogger is a simple adapter for cron to use zap logger
type cronLogger struct {
	logger *zap.Logger
}

func (l *cronLogger) Info(msg string, keysAndValues ...interface{}) {
	l.logger.Sugar().Infow(msg, keysAndValues...)
}

func (l *cronLogger) Error(err error, msg string, keysAndValues ...interface{}) {
	l.logger.Sugar().Errorw(msg, append(keysAndValues, "error", err)...)
}

// ProvideQuotaResetScheduler creates a new QuotaResetScheduler from config
func ProvideQuotaResetScheduler(
	cfg *config.Config,
	resetUsageUC *siteusecase.ResetMonthlyUsageUseCase,
	leaderElection leaderelection.LeaderElection,
	logger *zap.Logger,
) *QuotaResetScheduler {
	enabled := cfg.Scheduler.QuotaResetEnabled
	schedulePattern := cfg.Scheduler.QuotaResetSchedule

	// Create cron with logger
	cronLog := &cronLogger{logger: logger.Named("cron")}
	c := cron.New(
		cron.WithLogger(cronLog),
		cron.WithChain(
			cron.Recover(cronLog),
		),
	)

	return &QuotaResetScheduler{
		cron:            c,
		resetUsageUC:    resetUsageUC,
		leaderElection:  leaderElection,
		logger:          logger.Named("usage-reset-scheduler"),
		enabled:         enabled,
		schedulePattern: schedulePattern,
	}
}

// Start starts the quota reset scheduler
func (s *QuotaResetScheduler) Start() error {
	if !s.enabled {
		s.logger.Info("quota reset scheduler is disabled")
		return nil
	}

	s.logger.Info("starting quota reset scheduler",
		zap.String("schedule", s.schedulePattern))

	// Schedule the quota reset job
	_, err := s.cron.AddFunc(s.schedulePattern, s.resetQuotas)
	if err != nil {
		s.logger.Error("failed to schedule quota reset job", zap.Error(err))
		return err
	}

	// Start the cron scheduler
	s.cron.Start()

	s.logger.Info("quota reset scheduler started successfully")
	return nil
}

// Stop stops the quota reset scheduler
func (s *QuotaResetScheduler) Stop() {
	if !s.enabled {
		return
	}

	s.logger.Info("stopping quota reset scheduler")
	ctx := s.cron.Stop()
	<-ctx.Done()
	s.logger.Info("quota reset scheduler stopped")
}

// resetQuotas is the cron job function that resets monthly usage counters
func (s *QuotaResetScheduler) resetQuotas() {
	// Only execute if this instance is the leader
	if !s.leaderElection.IsLeader() {
		s.logger.Debug("skipping quota reset - not the leader instance",
			zap.String("instance_id", s.leaderElection.GetInstanceID()))
		return
	}

	s.logger.Info("executing scheduled usage reset as leader instance",
		zap.String("instance_id", s.leaderElection.GetInstanceID()))

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
	defer cancel()

	output, err := s.resetUsageUC.Execute(ctx)
	if err != nil {
		s.logger.Error("usage reset failed", zap.Error(err))
		return
	}

	s.logger.Info("usage reset completed",
		zap.Int("processed_sites", output.ProcessedSites),
		zap.Int("reset_count", output.ResetCount),
		zap.Int("failed_count", output.FailedCount),
		zap.Time("processed_at", output.ProcessedAt))
}