package main

import (
	"context"
	"errors"
	"strings"
	"testing"

	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/metrics"
)

func TestProcessFastMessageWritesTDengineAndRedisBeforeAck(t *testing.T) {
	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolGB32960, VIN: "VIN001", EventID: "evt-1"}
	payload, err := env.MarshalJSONBytes()
	if err != nil {
		t.Fatal(err)
	}
	appender := &recordingFastAppender{}
	updater := &recordingFastUpdater{}
	ackCount := 0
	msg := &fastMessage{data: payload, ack: func() error {
		ackCount++
		return nil
	}}

	if err := processFastMessage(context.Background(), nil, appender, updater, msg); err != nil {
		t.Fatalf("processFastMessage() error = %v", err)
	}
	if appender.count != 1 || updater.count != 1 || ackCount != 1 {
		t.Fatalf("appends=%d updates=%d acks=%d", appender.count, updater.count, ackCount)
	}
}

func TestProcessFastMessageDoesNotAckWhenRedisFails(t *testing.T) {
	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808, VIN: "VIN001", EventID: "evt-2"}
	payload, err := env.MarshalJSONBytes()
	if err != nil {
		t.Fatal(err)
	}
	appender := &recordingFastAppender{}
	updater := &recordingFastUpdater{err: errors.New("redis down")}
	ackCount := 0
	msg := &fastMessage{data: payload, ack: func() error {
		ackCount++
		return nil
	}}

	if err := processFastMessage(context.Background(), nil, appender, updater, msg); err == nil {
		t.Fatal("processFastMessage() error = nil, want redis failure")
	}
	if ackCount != 0 {
		t.Fatalf("ack count = %d, want 0", ackCount)
	}
}

func TestProcessFastMessageRecordsStageDurationMetrics(t *testing.T) {
	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808, VIN: "VIN001", EventID: "evt-3"}
	payload, err := env.MarshalJSONBytes()
	if err != nil {
		t.Fatal(err)
	}
	registry := metrics.NewRegistry()
	msg := &fastMessage{subject: "vehicle.raw.go.jt808.v1", data: payload, ack: func() error { return nil }}

	if err := processFastMessage(context.Background(), registry, &recordingFastAppender{}, &recordingFastUpdater{}, msg); err != nil {
		t.Fatalf("processFastMessage() error = %v", err)
	}

	text := registry.Render()
	for _, want := range []string{
		`vehicle_fast_writer_stage_duration_ms_histogram_bucket{le="+Inf",stage="tdengine",status="ok",subject="vehicle.raw.go.jt808.v1"} 1`,
		`vehicle_fast_writer_stage_duration_ms_histogram_count{stage="tdengine",status="ok",subject="vehicle.raw.go.jt808.v1"} 1`,
		`vehicle_fast_writer_stage_duration_ms_histogram_bucket{le="+Inf",stage="redis",status="ok",subject="vehicle.raw.go.jt808.v1"} 1`,
		`vehicle_fast_writer_stage_duration_ms_histogram_bucket{le="+Inf",stage="ack",status="ok",subject="vehicle.raw.go.jt808.v1"} 1`,
	} {
		if !strings.Contains(text, want) {
			t.Fatalf("fast writer stage metric missing %s:\n%s", want, text)
		}
	}
}

type recordingFastAppender struct {
	count int
	err   error
}

func (a *recordingFastAppender) AppendAll(context.Context, envelope.FrameEnvelope) error {
	a.count++
	return a.err
}

type recordingFastUpdater struct {
	count int
	err   error
}

func (u *recordingFastUpdater) FastUpdate(context.Context, envelope.FrameEnvelope) error {
	u.count++
	return u.err
}