package orchestrator

import (
	"context"
	"fmt"
	"time"

	v1 "github.com/garethgeorge/resticui/gen/go/v1"
	"github.com/garethgeorge/resticui/internal/oplog"
	"github.com/hashicorp/go-multierror"
)

type Task interface {
	Name() string                               // huamn readable name for this task.
	Next(now time.Time) *time.Time              // when this task would like to be run.
	Run(ctx context.Context) error              // run the task.
	Cancel(withStatus v1.OperationStatus) error // cancel the task's execution with the given status (either STATUS_USER_CANCELLED or STATUS_SYSTEM_CANCELLED).
}

// WithOperation is a utility that creates an operation to track the function's execution.
// timestamps are automatically added and the status is automatically updated if an error occurs.
func WithOperation(oplog *oplog.OpLog, op *v1.Operation, do func() error) error {
	if op.Id != 0 {
		if err := oplog.Update(op); err != nil {
			return fmt.Errorf("failed to add operation to oplog: %w", err)
		}
	} else {
		if err := oplog.Add(op); err != nil {
			return fmt.Errorf("failed to add operation to oplog: %w", err)
		}
	}

	if op.Status == v1.OperationStatus_STATUS_PENDING || op.Status == v1.OperationStatus_STATUS_UNKNOWN {
		op.Status = v1.OperationStatus_STATUS_INPROGRESS
	}
	err := do()
	if err != nil {
		op.Status = v1.OperationStatus_STATUS_ERROR
		op.DisplayMessage = err.Error()
	}
	op.UnixTimeEndMs = curTimeMillis()
	if op.Status == v1.OperationStatus_STATUS_INPROGRESS {
		op.Status = v1.OperationStatus_STATUS_SUCCESS
	}
	if e := oplog.Update(op); e != nil {
		return multierror.Append(err, fmt.Errorf("failed to update operation in oplog: %w", e))
	}
	return err
}

func timeToUnixMillis(t time.Time) int64 {
	return t.Unix()*1000 + int64(t.Nanosecond()/1000000)
}

func curTimeMillis() int64 {
	return timeToUnixMillis(time.Now())
}