// Copyright © 2020 Attestant Limited.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package standard

import (
	eth2client "github.com/attestantio/go-eth2-client"
	"github.com/attestantio/vouch/services/accountmanager"
	"github.com/attestantio/vouch/services/attestationaggregator"
	"github.com/attestantio/vouch/services/attester"
	"github.com/attestantio/vouch/services/beaconblockproposer"
	"github.com/attestantio/vouch/services/beaconcommitteesubscriber"
	"github.com/attestantio/vouch/services/chaintime"
	"github.com/attestantio/vouch/services/metrics"
	"github.com/attestantio/vouch/services/scheduler"
	"github.com/pkg/errors"
	"github.com/rs/zerolog"
)

type parameters struct {
	logLevel                     zerolog.Level
	monitor                      metrics.ControllerMonitor
	slotDurationProvider         eth2client.SlotDurationProvider
	slotsPerEpochProvider        eth2client.SlotsPerEpochProvider
	chainTimeService             chaintime.Service
	proposerDutiesProvider       eth2client.ProposerDutiesProvider
	attesterDutiesProvider       eth2client.AttesterDutiesProvider
	validatingAccountsProvider   accountmanager.ValidatingAccountsProvider
	scheduler                    scheduler.Service
	beaconChainHeadUpdatedSource eth2client.BeaconChainHeadUpdatedSource
	attester                     attester.Service
	beaconBlockProposer          beaconblockproposer.Service
	attestationAggregator        attestationaggregator.Service
	beaconCommitteeSubscriber    beaconcommitteesubscriber.Service
}

// Parameter is the interface for service parameters.
type Parameter interface {
	apply(*parameters)
}

type parameterFunc func(*parameters)

func (f parameterFunc) apply(p *parameters) {
	f(p)
}

// WithLogLevel sets the log level for the module.
func WithLogLevel(logLevel zerolog.Level) Parameter {
	return parameterFunc(func(p *parameters) {
		p.logLevel = logLevel
	})
}

// WithMonitor sets the monitor for the module.
func WithMonitor(monitor metrics.ControllerMonitor) Parameter {
	return parameterFunc(func(p *parameters) {
		p.monitor = monitor
	})
}

// WithSlotDurationProvider sets the slot duration provider.
func WithSlotDurationProvider(provider eth2client.SlotDurationProvider) Parameter {
	return parameterFunc(func(p *parameters) {
		p.slotDurationProvider = provider
	})
}

// WithSlotsPerEpochProvider sets the slots per epoch provider.
func WithSlotsPerEpochProvider(provider eth2client.SlotsPerEpochProvider) Parameter {
	return parameterFunc(func(p *parameters) {
		p.slotsPerEpochProvider = provider
	})
}

// WithChainTimeService sets the chain time service.
func WithChainTimeService(service chaintime.Service) Parameter {
	return parameterFunc(func(p *parameters) {
		p.chainTimeService = service
	})
}

// WithProposerDutiesProvider sets the proposer duties provider.
func WithProposerDutiesProvider(provider eth2client.ProposerDutiesProvider) Parameter {
	return parameterFunc(func(p *parameters) {
		p.proposerDutiesProvider = provider
	})
}

// WithAttesterDutiesProvider sets the attester duties provider.
func WithAttesterDutiesProvider(provider eth2client.AttesterDutiesProvider) Parameter {
	return parameterFunc(func(p *parameters) {
		p.attesterDutiesProvider = provider
	})
}

// WithBeaconChainHeadUpdatedSource sets the source for an OnBeaconChainHeadUpdated request
func WithBeaconChainHeadUpdatedSource(source eth2client.BeaconChainHeadUpdatedSource) Parameter {
	return parameterFunc(func(p *parameters) {
		p.beaconChainHeadUpdatedSource = source
	})
}

// WithValidatingAccountsProvider sets the validating accounts provider.
func WithValidatingAccountsProvider(provider accountmanager.ValidatingAccountsProvider) Parameter {
	return parameterFunc(func(p *parameters) {
		p.validatingAccountsProvider = provider
	})
}

// WithScheduler sets the scheduler.
func WithScheduler(scheduler scheduler.Service) Parameter {
	return parameterFunc(func(p *parameters) {
		p.scheduler = scheduler
	})
}

// WithAttester sets the attester.
func WithAttester(attester attester.Service) Parameter {
	return parameterFunc(func(p *parameters) {
		p.attester = attester
	})
}

// WithBeaconBlockProposer sets the beacon block propser.
func WithBeaconBlockProposer(proposer beaconblockproposer.Service) Parameter {
	return parameterFunc(func(p *parameters) {
		p.beaconBlockProposer = proposer
	})
}

// WithAttestationAggregator sets the attestation aggregator.
func WithAttestationAggregator(aggregator attestationaggregator.Service) Parameter {
	return parameterFunc(func(p *parameters) {
		p.attestationAggregator = aggregator
	})
}

// WithBeaconCommitteeSubscriber sets the beacon committee subscriber.
func WithBeaconCommitteeSubscriber(subscriber beaconcommitteesubscriber.Service) Parameter {
	return parameterFunc(func(p *parameters) {
		p.beaconCommitteeSubscriber = subscriber
	})
}

// parseAndCheckParameters parses and checks parameters to ensure that mandatory parameters are present and correct.
func parseAndCheckParameters(params ...Parameter) (*parameters, error) {
	parameters := parameters{
		logLevel: zerolog.GlobalLevel(),
	}
	for _, p := range params {
		if params != nil {
			p.apply(&parameters)
		}
	}

	if parameters.monitor == nil {
		return nil, errors.New("no monitor specified")
	}
	if parameters.slotDurationProvider == nil {
		return nil, errors.New("no slot duration provider specified")
	}
	if parameters.slotsPerEpochProvider == nil {
		return nil, errors.New("no slots per epoch provider specified")
	}
	if parameters.chainTimeService == nil {
		return nil, errors.New("no chain time service specified")
	}
	if parameters.proposerDutiesProvider == nil {
		return nil, errors.New("no proposer duties provider specified")
	}
	if parameters.attesterDutiesProvider == nil {
		return nil, errors.New("no attester duties provider specified")
	}
	if parameters.beaconChainHeadUpdatedSource == nil {
		return nil, errors.New("no beacon chain head updated source specified")
	}
	if parameters.scheduler == nil {
		return nil, errors.New("no scheduler service specified")
	}
	if parameters.attester == nil {
		return nil, errors.New("no attester specified")
	}
	if parameters.beaconBlockProposer == nil {
		return nil, errors.New("no beacon block proposer specified")
	}
	if parameters.attestationAggregator == nil {
		return nil, errors.New("no attestation aggregator specified")
	}
	if parameters.beaconCommitteeSubscriber == nil {
		return nil, errors.New("no beacon committee subscriber specified")
	}

	return &parameters, nil
}