package scheduler

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

	"github.com/go-co-op/gocron/v2"
	"go.mongodb.org/mongo-driver/bson/primitive"

	"scheduler-backend/internal/executor"
	"scheduler-backend/internal/jobdef"
	"scheduler-backend/internal/store/model"
)

type JobConfigStore interface {
	ListEnabled(ctx context.Context) ([]model.JobConfig, error)
	UpdateRunState(ctx context.Context, id primitive.ObjectID, status string, lastRunAt *time.Time) error
	UpdateNextRunAt(ctx context.Context, id primitive.ObjectID, nextRunAt *time.Time) error
}

type JobExecutionStore interface {
	Create(ctx context.Context, item *model.JobExecution) error
	UpdateResult(ctx context.Context, item *model.JobExecution) error
}

type Service struct {
	scheduler      gocron.Scheduler
	jobConfigStore JobConfigStore
	executionStore JobExecutionStore
	executor       *executor.Service
	runtime        jobdef.Runtime
}

func NewService(
	scheduler gocron.Scheduler,
	jobConfigStore JobConfigStore,
	executionStore JobExecutionStore,
	executor *executor.Service,
	runtime jobdef.Runtime,
) *Service {
	return &Service{
		scheduler:      scheduler,
		jobConfigStore: jobConfigStore,
		executionStore: executionStore,
		executor:       executor,
		runtime:        runtime,
	}
}

func (s *Service) RegisterEnabledJobs(ctx context.Context) error {
	items, err := s.jobConfigStore.ListEnabled(ctx)
	if err != nil {
		return err
	}

	for _, item := range items {
		if err := s.registerJob(ctx, item); err != nil {
			return err
		}
	}

	s.scheduler.Start()
	return nil
}

func (s *Service) Shutdown() error {
	return s.scheduler.Shutdown()
}

func (s *Service) registerJob(ctx context.Context, item model.JobConfig) error {
	switch item.ScheduleType {
	case "manual":
		return s.jobConfigStore.UpdateNextRunAt(ctx, item.ID, nil)
	case "cron":
		job, err := s.scheduler.NewJob(
			gocron.CronJob(item.ScheduleValue, false),
			gocron.NewTask(func() {
				s.runScheduledJob(context.Background(), item)
			}),
		)
		if err != nil {
			return fmt.Errorf("register cron job %s: %w", item.Name, err)
		}
		next, err := job.NextRun()
		if err != nil {
			return err
		}
		return s.jobConfigStore.UpdateNextRunAt(ctx, item.ID, &next)
	case "interval":
		duration, err := time.ParseDuration(item.ScheduleValue)
		if err != nil {
			return fmt.Errorf("parse interval for %s: %w", item.Name, err)
		}
		job, err := s.scheduler.NewJob(
			gocron.DurationJob(duration),
			gocron.NewTask(func() {
				s.runScheduledJob(context.Background(), item)
			}),
		)
		if err != nil {
			return fmt.Errorf("register interval job %s: %w", item.Name, err)
		}
		next, err := job.NextRun()
		if err != nil {
			return err
		}
		return s.jobConfigStore.UpdateNextRunAt(ctx, item.ID, &next)
	default:
		return fmt.Errorf("unsupported schedule type %s", item.ScheduleType)
	}
}

func (s *Service) runScheduledJob(ctx context.Context, job model.JobConfig) {
	now := time.Now()
	params := json.RawMessage(job.DefaultParams)
	record := model.JobExecution{
		JobConfigID:    job.ID,
		TriggerType:    "schedule",
		Status:         "running",
		ParamsSnapshot: string(params),
		StartedAt:      &now,
		CreatedAt:      now,
	}

	if err := s.executionStore.Create(ctx, &record); err != nil {
		s.runtime.Logger.Error("create scheduled execution failed", "jobID", job.ID.Hex(), "error", err)
		return
	}

	execReq := jobdef.ExecuteRequest{
		ExecutionID:  record.ID.Hex(),
		JobID:        job.ID.Hex(),
		TriggerType:  "schedule",
		Params:       params,
		LogCollector: jobdef.NewLogCollector(),
	}
	runErr := s.executor.Execute(ctx, job.HandlerKey, execReq)

	finishedAt := time.Now()
	record.FinishedAt = &finishedAt
	record.DurationMs = finishedAt.Sub(now).Milliseconds()
	flushed := execReq.LogCollector.Flush(record.ID.Hex())
	if runErr != nil {
		record.Status = "failed"
		record.ErrorMessage = runErr.Error()
		record.ResultSummary = "scheduled execution failed"
		if flushed.LogText != "" {
			record.LogText = flushed.LogText
		} else {
			record.LogText = runErr.Error()
		}
		record.LogFile = flushed.LogFile
		_ = s.jobConfigStore.UpdateRunState(ctx, job.ID, "failed", &finishedAt)
	} else {
		record.Status = "success"
		record.ResultSummary = "scheduled execution succeeded"
		if flushed.LogText != "" {
			record.LogText = flushed.LogText
		} else {
			record.LogText = "handler executed successfully"
		}
		record.LogFile = flushed.LogFile
		_ = s.jobConfigStore.UpdateRunState(ctx, job.ID, "success", &finishedAt)
	}

	if err := s.executionStore.UpdateResult(ctx, &record); err != nil {
		s.runtime.Logger.Error("update scheduled execution failed", "executionID", record.ID.Hex(), "error", err)
	}
}