package state

import (
	memdb "github.com/hashicorp/go-memdb"
	"github.com/hashicorp/nomad/nomad/structs"
)

var MsgTypeEvents = map[structs.MessageType]string{
	structs.NodeRegisterRequestType:                 structs.TypeNodeRegistration,
	structs.NodeDeregisterRequestType:               structs.TypeNodeDeregistration,
	structs.UpsertNodeEventsType:                    structs.TypeNodeEvent,
	structs.EvalUpdateRequestType:                   structs.TypeEvalUpdated,
	structs.AllocClientUpdateRequestType:            structs.TypeAllocationUpdated,
	structs.JobRegisterRequestType:                  structs.TypeJobRegistered,
	structs.AllocUpdateRequestType:                  structs.TypeAllocationUpdated,
	structs.NodeUpdateStatusRequestType:             structs.TypeNodeEvent,
	structs.JobDeregisterRequestType:                structs.TypeJobDeregistered,
	structs.JobBatchDeregisterRequestType:           structs.TypeJobBatchDeregistered,
	structs.AllocUpdateDesiredTransitionRequestType: structs.TypeAllocationUpdateDesiredStatus,
	structs.NodeUpdateEligibilityRequestType:        structs.TypeNodeDrain,
	structs.NodeUpdateDrainRequestType:              structs.TypeNodeDrain,
	structs.BatchNodeUpdateDrainRequestType:         structs.TypeNodeDrain,
	structs.DeploymentStatusUpdateRequestType:       structs.TypeDeploymentUpdate,
	structs.DeploymentPromoteRequestType:            structs.TypeDeploymentPromotion,
	structs.DeploymentAllocHealthRequestType:        structs.TypeDeploymentAllocHealth,
	structs.ApplyPlanResultsRequestType:             structs.TypePlanResult,
	structs.ACLTokenDeleteRequestType:               structs.TypeACLTokenDeleted,
	structs.ACLTokenUpsertRequestType:               structs.TypeACLTokenUpserted,
	structs.ACLPolicyDeleteRequestType:              structs.TypeACLPolicyDeleted,
	structs.ACLPolicyUpsertRequestType:              structs.TypeACLPolicyUpserted,
}

func eventsFromChanges(tx ReadTxn, changes Changes) *structs.Events {
	eventType, ok := MsgTypeEvents[changes.MsgType]
	if !ok {
		return nil
	}

	var events []structs.Event
	for _, change := range changes.Changes {
		if event, ok := eventFromChange(change); ok {
			event.Type = eventType
			event.Index = changes.Index
			events = append(events, event)
		}
	}

	return &structs.Events{Index: changes.Index, Events: events}
}

func eventFromChange(change memdb.Change) (structs.Event, bool) {
	if change.Deleted() {
		switch change.Table {
		case "acl_token":
			before, ok := change.Before.(*structs.ACLToken)
			if !ok {
				return structs.Event{}, false
			}
			return structs.Event{
				Topic: structs.TopicACLToken,
				Key:   before.AccessorID,
				Payload: structs.ACLTokenEvent{
					ACLToken: before,
				},
			}, true
		case "acl_policy":
			before, ok := change.Before.(*structs.ACLPolicy)
			if !ok {
				return structs.Event{}, false
			}
			return structs.Event{
				Topic: structs.TopicACLPolicy,
				Key:   before.Name,
				Payload: structs.ACLPolicyEvent{
					ACLPolicy: before,
				},
			}, true
		case "nodes":
			before, ok := change.Before.(*structs.Node)
			if !ok {
				return structs.Event{}, false
			}
			return structs.Event{
				Topic: structs.TopicNode,
				Key:   before.ID,
				Payload: &structs.NodeStreamEvent{
					Node: before,
				},
			}, true
		}
		return structs.Event{}, false
	}

	switch change.Table {
	case "acl_token":
		after, ok := change.After.(*structs.ACLToken)
		if !ok {
			return structs.Event{}, false
		}
		return structs.Event{
			Topic: structs.TopicACLToken,
			Key:   after.AccessorID,
			Payload: structs.ACLTokenEvent{
				ACLToken: after,
			},
		}, true
	case "acl_policy":
		after, ok := change.After.(*structs.ACLPolicy)
		if !ok {
			return structs.Event{}, false
		}
		return structs.Event{
			Topic: structs.TopicACLPolicy,
			Key:   after.Name,
			Payload: structs.ACLPolicyEvent{
				ACLPolicy: after,
			},
		}, true
	case "evals":
		after, ok := change.After.(*structs.Evaluation)
		if !ok {
			return structs.Event{}, false
		}
		return structs.Event{
			Topic: structs.TopicEvaluation,
			Key:   after.ID,
			FilterKeys: []string{
				after.JobID,
				after.DeploymentID,
			},
			Namespace: after.Namespace,
			Payload: &structs.EvaluationEvent{
				Evaluation: after,
			},
		}, true
	case "allocs":
		after, ok := change.After.(*structs.Allocation)
		if !ok {
			return structs.Event{}, false
		}
		alloc := after.Copy()

		filterKeys := []string{
			alloc.JobID,
			alloc.DeploymentID,
		}

		// remove job info to help keep size of alloc event down
		alloc.Job = nil

		return structs.Event{
			Topic:      structs.TopicAllocation,
			Key:        after.ID,
			FilterKeys: filterKeys,
			Namespace:  after.Namespace,
			Payload: &structs.AllocationEvent{
				Allocation: alloc,
			},
		}, true
	case "jobs":
		after, ok := change.After.(*structs.Job)
		if !ok {
			return structs.Event{}, false
		}
		return structs.Event{
			Topic:     structs.TopicJob,
			Key:       after.ID,
			Namespace: after.Namespace,
			Payload: &structs.JobEvent{
				Job: after,
			},
		}, true
	case "nodes":
		after, ok := change.After.(*structs.Node)
		if !ok {
			return structs.Event{}, false
		}
		return structs.Event{
			Topic: structs.TopicNode,
			Key:   after.ID,
			Payload: &structs.NodeStreamEvent{
				Node: after,
			},
		}, true
	case "deployment":
		after, ok := change.After.(*structs.Deployment)
		if !ok {
			return structs.Event{}, false
		}
		return structs.Event{
			Topic:      structs.TopicDeployment,
			Key:        after.ID,
			Namespace:  after.Namespace,
			FilterKeys: []string{after.JobID},
			Payload: &structs.DeploymentEvent{
				Deployment: after,
			},
		}, true
	}

	return structs.Event{}, false
}