package events

import (
	"context"
	"encoding/json"
	"fmt"

	"github.com/redis/go-redis/v9"
)

const channel = "agent-mgr:events"

type Bus struct {
	rdb *redis.Client
}

type Event struct {
	Type      string `json:"type"` // "session.started", "session.completed", "session.failed", "session.stopped", "app.status"
	SessionID string `json:"session_id,omitempty"`
	AppID     string `json:"app_id,omitempty"`
	Status    string `json:"status,omitempty"`
	Message   string `json:"message,omitempty"`
}

func NewBus(addr, password string) *Bus {
	return &Bus{
		rdb: redis.NewClient(&redis.Options{
			Addr:     addr,
			Password: password,
		}),
	}
}

func (b *Bus) Publish(ctx context.Context, evt Event) error {
	data, err := json.Marshal(evt)
	if err != nil {
		return fmt.Errorf("marshal event: %w", err)
	}
	return b.rdb.Publish(ctx, channel, data).Err()
}

func (b *Bus) Subscribe(ctx context.Context) (<-chan Event, error) {
	sub := b.rdb.Subscribe(ctx, channel)
	ch := make(chan Event, 64)

	go func() {
		defer close(ch)
		defer sub.Close()
		for {
			msg, err := sub.ReceiveMessage(ctx)
			if err != nil {
				return
			}
			var evt Event
			if err := json.Unmarshal([]byte(msg.Payload), &evt); err != nil {
				continue
			}
			select {
			case ch <- evt:
			case <-ctx.Done():
				return
			}
		}
	}()

	return ch, nil
}

func (b *Bus) Close() error {
	return b.rdb.Close()
}