package client

import (
	"context"

	pb "github.com/prysmaticlabs/prysm/proto/beacon/rpc/v1"
	"github.com/prysmaticlabs/prysm/shared/params"
	"github.com/sirupsen/logrus"
	"go.opencensus.io/trace"
)

// Validator interface defines the primary methods of a validator client.
type Validator interface {
	Done()
	WaitForChainStart(ctx context.Context) error
	WaitForActivation(ctx context.Context) error
	NextSlot() <-chan uint64
	UpdateAssignments(ctx context.Context, slot uint64) error
	RoleAt(slot uint64) pb.ValidatorRole
	AttestToBlockHead(ctx context.Context, slot uint64)
	ProposeBlock(ctx context.Context, slot uint64)
}

// Run the main validator routine. This routine exits if the context is
// cancelled.
//
// Order of operations:
// 1 - Initialize validator data
// 2 - Wait for validator activation
// 3 - Wait for the next slot start
// 4 - Update assignments
// 5 - Determine role at current slot
// 6 - Perform assigned role, if any
func run(ctx context.Context, v Validator) {
	defer v.Done()
	if err := v.WaitForChainStart(ctx); err != nil {
		log.Fatalf("Could not determine if beacon chain started: %v", err)
	}
	if err := v.WaitForActivation(ctx); err != nil {
		log.Fatalf("Could not wait for validator activation: %v", err)
	}
	if err := v.UpdateAssignments(ctx, params.BeaconConfig().GenesisSlot); err != nil {
		log.WithField("error", err).Error("Failed to update assignments")
	}
	for {
		ctx, span := trace.StartSpan(ctx, "processSlot")
		defer span.End()

		select {
		case <-ctx.Done():
			log.Info("Context cancelled, stopping validator")
			return // Exit if context is cancelled.
		case slot := <-v.NextSlot():
			span.AddAttributes(trace.Int64Attribute("slot", int64(slot)))

			if err := v.UpdateAssignments(ctx, slot); err != nil {
				log.WithField("error", err).Error("Failed to update assignments")
				continue
			}
			role := v.RoleAt(slot)

			switch role {
			case pb.ValidatorRole_BOTH:
				v.ProposeBlock(ctx, slot)
				v.AttestToBlockHead(ctx, slot)
			case pb.ValidatorRole_ATTESTER:
				v.AttestToBlockHead(ctx, slot)
			case pb.ValidatorRole_PROPOSER:
				v.ProposeBlock(ctx, slot)
			case pb.ValidatorRole_UNKNOWN:
				// This shouldn't happen normally, so it is considered a warning.
				log.WithFields(logrus.Fields{
					"slot": slot - params.BeaconConfig().GenesisSlot,
					"role": role,
				}).Info("Unknown role, doing nothing")
			default:
				// Do nothing :)
			}
		}
	}
}