package batch

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

	"git.cactoz.su/cacto/home_automatization/services/ingest-service/internal/telemetry"
)

func discardLogger() *slog.Logger {
	return slog.New(slog.NewTextHandler(io.Discard, nil))
}

func reading(deviceID string) telemetry.Reading {
	return telemetry.Reading{DeviceID: deviceID, ZoneID: "z1", SensorType: "temperature", Value: 1}
}

func awaitBatch(t *testing.T, flushed chan []telemetry.Reading, timeout time.Duration) []telemetry.Reading {
	t.Helper()
	select {
	case batch := <-flushed:
		return batch
	case <-time.After(timeout):
		t.Fatal("timed out waiting for flush")
		return nil
	}
}

func TestBatcher_FlushesOnSize(t *testing.T) {
	flushed := make(chan []telemetry.Reading, 1)
	b := New(3, time.Hour, time.Second, func(_ context.Context, r []telemetry.Reading) error {
		flushed <- r
		return nil
	}, discardLogger())
	b.Start()
	defer b.Stop()

	b.Add(reading("a"))
	b.Add(reading("b"))
	b.Add(reading("c")) // hits maxSize, should trigger an immediate flush

	batch := awaitBatch(t, flushed, time.Second)
	if len(batch) != 3 {
		t.Fatalf("got %d readings, want 3", len(batch))
	}
}

func TestBatcher_FlushesOnInterval(t *testing.T) {
	flushed := make(chan []telemetry.Reading, 1)
	b := New(100, 20*time.Millisecond, time.Second, func(_ context.Context, r []telemetry.Reading) error {
		flushed <- r
		return nil
	}, discardLogger())
	b.Start()
	defer b.Stop()

	b.Add(reading("a"))

	batch := awaitBatch(t, flushed, time.Second)
	if len(batch) != 1 {
		t.Fatalf("got %d readings, want 1", len(batch))
	}
}

func TestBatcher_StopFlushesRemainder(t *testing.T) {
	flushed := make(chan []telemetry.Reading, 1)
	b := New(100, time.Hour, time.Second, func(_ context.Context, r []telemetry.Reading) error {
		flushed <- r
		return nil
	}, discardLogger())
	b.Start()

	b.Add(reading("a"))
	b.Add(reading("b"))
	b.Stop()

	batch := awaitBatch(t, flushed, time.Second)
	if len(batch) != 2 {
		t.Fatalf("got %d readings, want 2", len(batch))
	}
}