package backend

import (
	"context"
	"io"
	"log/slog"
	"testing"
	"time"

	"github.com/eclipse/paho.golang/paho"
	"robot-market/test-mqtt-5/internal/config"
	"robot-market/test-mqtt-5/internal/contracts"
	"robot-market/test-mqtt-5/internal/events"
	"robot-market/test-mqtt-5/internal/mqtt"
)

func testBackend() *Backend {
	c := config.Defaults()
	return New(mqtt.New(c, events.NewStore(32, slog.New(slog.NewTextHandler(io.Discard, nil)))))
}
func TestNativeCorrelationAndResult(t *testing.T) {
	for _, bad := range []string{"topic", "device", "correlation", "retained", "response", "result", "expired"} {
		t.Run(bad, func(t *testing.T) {
			b := testBackend()
			cmd := NewCommand("sim-001", "ping", ID(), 15*time.Second)
			p, err := b.register(cmd)
			if err != nil {
				t.Fatal(err)
			}
			yes := true
			ack := contracts.Ack{Envelope: cmd.Envelope, RequestID: cmd.RequestID, Timestamp: Timestamp(time.Now()), Stage: "completed", OK: &yes, Result: &contracts.Result{Pong: &yes}}
			if bad == "device" {
				ack.DeviceID = "other"
			}
			if bad == "result" {
				ack.Result = &contracts.Result{Version: "1.0.0"}
			}
			packet := mqtt.Packet(mqtt.Topic(b.Client.Config, "acks"), 1, false, ack)
			packet.Properties.CorrelationData = []byte(cmd.RequestID)
			switch bad {
			case "topic":
				packet.Topic = "robot-market/test/v1/other/acks"
			case "correlation":
				packet.Properties.CorrelationData = []byte("wrong")
			case "retained":
				packet.Retain = true
			case "response":
				packet.Properties.ResponseTopic = "unexpected"
			case "expired":
				p.expires = time.Now().Add(-time.Second)
			}
			b.Handle(packet)
			select {
			case <-p.result:
				t.Fatal("invalid ACK completed request")
			default:
			}
		})
	}
	b := testBackend()
	cmd := NewCommand("sim-001", "ping", ID(), 15*time.Second)
	p, _ := b.register(cmd)
	yes := true
	ack := contracts.Ack{Envelope: cmd.Envelope, RequestID: cmd.RequestID, Timestamp: Timestamp(time.Now()), Stage: "completed", OK: &yes, Result: &contracts.Result{Pong: &yes}}
	packet := mqtt.Packet(mqtt.Topic(b.Client.Config, "acks"), 1, false, ack)
	packet.Properties.CorrelationData = []byte(cmd.RequestID)
	// Completion may precede accepted. A subsequent accepted/duplicate cannot regress it.
	b.Handle(packet)
	ack.Stage = "accepted"
	ack.Result = nil
	accepted := mqtt.Packet(packet.Topic, 1, false, ack)
	accepted.Properties.CorrelationData = []byte(cmd.RequestID)
	b.Handle(accepted)
	b.Handle(packet)
	select {
	case result := <-p.result:
		if result.Err != nil || result.Ack.Stage != "completed" {
			t.Fatal("wrong completion")
		}
	default:
		t.Fatal("valid completion ignored")
	}
	select {
	case <-p.result:
		t.Fatal("completion delivered twice")
	default:
	}
}
func TestPendingLimitsAndDisconnect(t *testing.T) {
	b := testBackend()
	b.Client.Config.Limits.PendingCommands = 1
	cmd := NewCommand("sim-001", "ping", ID(), 15*time.Second)
	p, _ := b.register(cmd)
	if _, err := b.register(NewCommand("sim-001", "ping", ID(), 15*time.Second)); err == nil {
		t.Fatal("capacity ignored")
	}
	b.Disconnect()
	b.Disconnect()
	result := <-p.result
	if result.Err == nil {
		t.Fatal("disconnect claimed success")
	}
	if _, err := b.Command(context.Background(), cmd); err == nil {
		t.Fatal("disconnected command admitted")
	}
}

func TestObserveDeviceAndInvalidPayloadDiagnostics(t *testing.T) {
	b := testBackend()
	b.Client.Config.Topics.ObserveDevices = "sim-001,esp32-lab-001"
	b.Client.Config.Logging.RawPayloads = true
	payload := []byte(`{"schema_version":1,"device_id":"esp32-lab-001","message_id":"real-device","boot_id":"boot-1","sequence":1,"timestamp":"2026-10-07T00:00:00Z","readings":{"uptime_s":12}}`)
	b.Handle(&paho.Publish{Topic: "robot-market/test/v1/esp32-lab-001/telemetry", Payload: payload})
	b.Handle(&paho.Publish{Topic: "robot-market/test/v1/esp32-lab-001/telemetry", Payload: []byte("hello from esp32")})
	history, counts := b.Client.Events.Snapshot()
	if counts[events.MessageReceived] != 1 || counts[events.ValidationFailed] != 1 {
		t.Fatal("device receipt and contract failure must be distinct")
	}
	if history[0].DeviceID != "esp32-lab-001" || history[0].Payload.Text != string(payload) {
		t.Fatal("ESP32 identity/payload was lost")
	}
	if history[1].Payload.Text != "hello from esp32" || history[1].Outcome == "" {
		t.Fatal("invalid external payload needs diagnostic visibility")
	}
	b.Client.Config.Logging.RawPayloads = false
	b.Handle(&paho.Publish{Topic: "robot-market/test/v1/esp32-lab-001/telemetry", Payload: []byte("private invalid input")})
	history, _ = b.Client.Events.Snapshot()
	if !history[2].Payload.Omitted || history[2].Payload.Text != "" {
		t.Fatal("raw payload display must require explicit opt-in")
	}
}

func TestOtherObservedDeviceCannotCompletePendingCommand(t *testing.T) {
	b := testBackend()
	b.Client.Config.Topics.ObserveDevices = "esp32-lab-001"
	cmd := NewCommand("sim-001", "ping", ID(), 15*time.Second)
	pending, _ := b.register(cmd)
	yes := true
	ack := contracts.Ack{Envelope: contracts.Envelope{SchemaVersion: 1, DeviceID: "esp32-lab-001"}, RequestID: cmd.RequestID, Timestamp: Timestamp(time.Now()), Stage: "completed", OK: &yes, Result: &contracts.Result{Pong: &yes}}
	packet := mqtt.Packet("robot-market/test/v1/esp32-lab-001/acks", 1, false, ack)
	packet.Properties.CorrelationData = []byte(cmd.RequestID)
	b.Handle(packet)
	select {
	case <-pending.result:
		t.Fatal("another device completed an own command")
	default:
	}
}

func TestRawObservationAcceptsArbitraryPayloadsAndTopics(t *testing.T) {
	b := testBackend()
	b.Client.Config.Topics.ObserveAll = true
	for _, payload := range []string{"hello", `{"device_id":"different","timestamp":"{{$isoTimestamp}}"}`, "", "[1,2,3]"} {
		b.Handle(&paho.Publish{Topic: "robot-market/test/v1/arbitrary/custom-topic", Payload: []byte(payload)})
	}
	history, counts := b.Client.Events.Snapshot()
	if counts[events.MessageReceived] != 4 || counts[events.ValidationFailed] != 0 {
		t.Fatal("raw observation incorrectly validated a payload")
	}
	if history[1].Payload.Text != `{"device_id":"different","timestamp":"{{$isoTimestamp}}"}` || history[1].DeviceID != "arbitrary" {
		t.Fatal("raw observation lost payload or topic metadata")
	}
}