package types

import (
	"encoding/json"
	"fmt"
	"reflect"
	"slices"
	"strings"

	abci "github.com/cometbft/cometbft/api/cometbft/abci/v1"
	"github.com/cosmos/gogoproto/jsonpb"
	"github.com/cosmos/gogoproto/proto"
	"golang.org/x/exp/maps"

	"github.com/cosmos/cosmos-sdk/codec"
)

type EventManagerI interface {
	Events() Events
	ABCIEvents() []abci.Event
	EmitTypedEvent(tev proto.Message) error
	EmitTypedEvents(tevs ...proto.Message) error
	EmitEvent(event Event)
	EmitEvents(events Events)
}

// ----------------------------------------------------------------------------
// Event Manager
// ----------------------------------------------------------------------------

var _ EventManagerI = (*EventManager)(nil)

// EventManager implements a simple wrapper around a slice of Event objects that
// can be emitted from.
type EventManager struct {
	events Events
}

func NewEventManager() *EventManager {
	return &EventManager{EmptyEvents()}
}

func (em *EventManager) Events() Events { return em.events }

// EmitEvent stores a single Event object.
// Deprecated: Use EmitTypedEvent
func (em *EventManager) EmitEvent(event Event) {
	em.events = em.events.AppendEvent(event)
}

// EmitEvents stores a series of Event objects.
// Deprecated: Use EmitTypedEvents
func (em *EventManager) EmitEvents(events Events) {
	em.events = em.events.AppendEvents(events)
}

// ABCIEvents returns all stored Event objects as abci.Event objects.
func (em EventManager) ABCIEvents() []abci.Event {
	return em.events.ToABCIEvents()
}

// EmitTypedEvent takes typed event and emits converting it into Event
func (em *EventManager) EmitTypedEvent(tev proto.Message) error {
	event, err := TypedEventToEvent(tev)
	if err != nil {
		return err
	}

	em.EmitEvent(event)
	return nil
}

// EmitTypedEvents takes series of typed events and emit
func (em *EventManager) EmitTypedEvents(tevs ...proto.Message) error {
	events := make(Events, len(tevs))
	for i, tev := range tevs {
		res, err := TypedEventToEvent(tev)
		if err != nil {
			return err
		}
		events[i] = res
	}

	em.EmitEvents(events)
	return nil
}

// TypedEventToEvent takes typed event and converts to Event object
func TypedEventToEvent(tev proto.Message) (Event, error) {
	evtType := proto.MessageName(tev)
	evtJSON, err := codec.ProtoMarshalJSON(tev, nil)
	if err != nil {
		return Event{}, err
	}

	var attrMap map[string]json.RawMessage
	err = json.Unmarshal(evtJSON, &attrMap)
	if err != nil {
		return Event{}, err
	}

	// sort the keys to ensure the order is always the same
	keys := maps.Keys(attrMap)
	slices.Sort(keys)

	attrs := make([]abci.EventAttribute, 0, len(attrMap))
	for _, k := range keys {
		v := attrMap[k]
		attrs = append(attrs, abci.EventAttribute{
			Key:   k,
			Value: string(v),
		})
	}

	return Event{
		Type:       evtType,
		Attributes: attrs,
	}, nil
}

// ParseTypedEvent converts abci.Event back to a typed event.
func ParseTypedEvent(event abci.Event) (proto.Message, error) {
	concreteGoType := proto.MessageType(event.Type)
	if concreteGoType == nil {
		return nil, fmt.Errorf("failed to retrieve the message of type %q", event.Type)
	}

	var value reflect.Value
	if concreteGoType.Kind() == reflect.Ptr {
		value = reflect.New(concreteGoType.Elem())
	} else {
		value = reflect.Zero(concreteGoType)
	}

	protoMsg, ok := value.Interface().(proto.Message)
	if !ok {
		return nil, fmt.Errorf("%q does not implement proto.Message", event.Type)
	}

	attrMap := make(map[string]json.RawMessage)
	for _, attr := range event.Attributes {
		attrMap[attr.Key] = json.RawMessage(attr.Value)
	}

	attrBytes, err := json.Marshal(attrMap)
	if err != nil {
		return nil, err
	}

	unmarshaler := jsonpb.Unmarshaler{AllowUnknownFields: true}
	if err := unmarshaler.Unmarshal(strings.NewReader(string(attrBytes)), protoMsg); err != nil {
		return nil, err
	}

	return protoMsg, nil
}

// ----------------------------------------------------------------------------
// Events
// ----------------------------------------------------------------------------

type (
	// Event is a type alias for an ABCI Event
	Event abci.Event

	// Events defines a slice of Event objects
	Events []Event
)

// NewEvent creates a new Event object with a given type and slice of one or more
// attributes.
func NewEvent(ty string, attrs ...Attribute) Event {
	e := Event{Type: ty}

	for _, attr := range attrs {
		e.Attributes = append(e.Attributes, attr.ToKVPair())
	}

	return e
}

// NewAttribute returns a new key/value Attribute object.
func NewAttribute(k, v string) Attribute {
	return Attribute{k, v}
}

// EmptyEvents returns an empty slice of events.
func EmptyEvents() Events {
	return make(Events, 0)
}

func (a Attribute) String() string {
	return fmt.Sprintf("%s: %s", a.Key, a.Value)
}

// ToKVPair converts an Attribute object into a CometBFT key/value pair.
func (a Attribute) ToKVPair() abci.EventAttribute {
	return abci.EventAttribute{Key: a.Key, Value: a.Value}
}

// AppendAttributes adds one or more attributes to an Event.
func (e Event) AppendAttributes(attrs ...Attribute) Event {
	for _, attr := range attrs {
		e.Attributes = append(e.Attributes, attr.ToKVPair())
	}
	return e
}

// GetAttribute returns an attribute for a given key present in an event.
// If the key is not found, the boolean value will be false.
func (e Event) GetAttribute(key string) (Attribute, bool) {
	for _, attr := range e.Attributes {
		if attr.Key == key {
			return Attribute{Key: attr.Key, Value: attr.Value}, true
		}
	}
	return Attribute{}, false
}

// AppendEvent adds an Event to a slice of events.
func (e Events) AppendEvent(event Event) Events {
	return append(e, event)
}

// AppendEvents adds a slice of Event objects to an exist slice of Event objects.
func (e Events) AppendEvents(events Events) Events {
	return append(e, events...)
}

// ToABCIEvents converts a slice of Event objects to a slice of abci.Event
// objects.
func (e Events) ToABCIEvents() []abci.Event {
	res := make([]abci.Event, len(e))
	for i, ev := range e {
		res[i] = abci.Event{Type: ev.Type, Attributes: ev.Attributes}
	}

	return res
}

// GetAttributes returns all attributes matching a given key present in events.
// If the key is not found, the boolean value will be false.
func (e Events) GetAttributes(key string) ([]Attribute, bool) {
	attrs := make([]Attribute, 0)
	for _, event := range e {
		if attr, found := event.GetAttribute(key); found {
			attrs = append(attrs, attr)
		}
	}

	return attrs, len(attrs) > 0
}

// Common event types and attribute keys
const (
	EventTypeTx = "tx"

	AttributeKeyAccountSequence = "acc_seq"
	AttributeKeySignature       = "signature"
	AttributeKeyFee             = "fee"
	AttributeKeyFeePayer        = "fee_payer"

	EventTypeMessage = "message"

	AttributeKeyAction = "action"
	AttributeKeyModule = "module"
	AttributeKeySender = "sender"
	AttributeKeyAmount = "amount"
)

type (
	// StringAttributes defines a slice of StringEvents objects.
	StringEvents []StringEvent
)

func (se StringEvents) String() string {
	var sb strings.Builder

	for _, e := range se {
		fmt.Fprintf(&sb, "\t\t- %s\n", e.Type)

		for _, attr := range e.Attributes {
			fmt.Fprintf(&sb, "\t\t\t- %s\n", attr)
		}
	}

	return strings.TrimRight(sb.String(), "\n")
}

// StringifyEvent converts an Event object to a StringEvent object.
func StringifyEvent(e abci.Event) StringEvent {
	res := StringEvent{Type: e.Type}

	for _, attr := range e.Attributes {
		res.Attributes = append(
			res.Attributes,
			Attribute{Key: attr.Key, Value: attr.Value},
		)
	}

	return res
}

// StringifyEvents converts a slice of Event objects into a slice of StringEvent
// objects.
func StringifyEvents(events []abci.Event) StringEvents {
	res := make(StringEvents, 0, len(events))

	for _, e := range events {
		res = append(res, StringifyEvent(e))
	}

	return res
}

// MarkEventsToIndex returns the set of ABCI events, where each event's attribute
// has it's index value marked based on the provided set of events to index.
func MarkEventsToIndex(events []abci.Event, indexSet map[string]struct{}) []abci.Event {
	indexAll := len(indexSet) == 0
	updatedEvents := make([]abci.Event, len(events))

	for i, e := range events {
		updatedEvent := abci.Event{
			Type:       e.Type,
			Attributes: make([]abci.EventAttribute, len(e.Attributes)),
		}

		for j, attr := range e.Attributes {
			_, index := indexSet[fmt.Sprintf("%s.%s", e.Type, attr.Key)]
			updatedAttr := abci.EventAttribute{
				Key:   attr.Key,
				Value: attr.Value,
				Index: index || indexAll,
			}

			updatedEvent.Attributes[j] = updatedAttr
		}

		updatedEvents[i] = updatedEvent
	}

	return updatedEvents
}