package redisstate_test

import (
	"context"
	"strconv"
	"testing"
	"time"

	"galaxy/lobby/internal/adapters/redisstate"

	"github.com/alicebob/miniredis/v2"
	"github.com/redis/go-redis/v9"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func newLagTestProbe(t *testing.T, now time.Time) (*redisstate.StreamLagProbe, *miniredis.Miniredis, *redis.Client) {
	t.Helper()
	server := miniredis.RunT(t)
	client := redis.NewClient(&redis.Options{Addr: server.Addr()})
	t.Cleanup(func() {
		_ = client.Close()
	})
	probe, err := redisstate.NewStreamLagProbe(client, func() time.Time { return now })
	require.NoError(t, err)
	return probe, server, client
}

func TestStreamLagProbeReturnsAgeOfNextEntry(t *testing.T) {
	now := time.UnixMilli(2_000_000_000_000).UTC()
	probe, _, client := newLagTestProbe(t, now)
	ctx := context.Background()

	addEntry := func(ms int64) string {
		id, err := client.XAdd(ctx, &redis.XAddArgs{
			Stream: "demo",
			ID:     formatEntryID(ms, 0),
			Values: map[string]any{"k": "v"},
		}).Result()
		require.NoError(t, err)
		return id
	}

	saved := addEntry(now.UnixMilli() - 5_000) // already processed
	addEntry(now.UnixMilli() - 1_500)          // first unprocessed → 1.5s old

	age, ok, err := probe.OldestUnprocessedAge(ctx, "demo", saved)
	require.NoError(t, err)
	require.True(t, ok)
	assert.InDelta(t, (1_500 * time.Millisecond).Milliseconds(), age.Milliseconds(), 50)
}

func TestStreamLagProbeReturnsFalseWhenAtTail(t *testing.T) {
	now := time.UnixMilli(2_000_000_000_000).UTC()
	probe, _, client := newLagTestProbe(t, now)
	ctx := context.Background()

	id, err := client.XAdd(ctx, &redis.XAddArgs{
		Stream: "demo",
		ID:     formatEntryID(now.UnixMilli()-2_000, 0),
		Values: map[string]any{"k": "v"},
	}).Result()
	require.NoError(t, err)

	age, ok, err := probe.OldestUnprocessedAge(ctx, "demo", id)
	require.NoError(t, err)
	require.False(t, ok)
	assert.Zero(t, age)
}

func TestStreamLagProbeFallsBackToHeadOnEmptyOffset(t *testing.T) {
	now := time.UnixMilli(2_000_000_000_000).UTC()
	probe, _, client := newLagTestProbe(t, now)
	ctx := context.Background()

	_, err := client.XAdd(ctx, &redis.XAddArgs{
		Stream: "demo",
		ID:     formatEntryID(now.UnixMilli()-3_000, 0),
		Values: map[string]any{"k": "v"},
	}).Result()
	require.NoError(t, err)

	age, ok, err := probe.OldestUnprocessedAge(ctx, "demo", "")
	require.NoError(t, err)
	require.True(t, ok)
	assert.InDelta(t, (3 * time.Second).Milliseconds(), age.Milliseconds(), 50)
}

func TestStreamLagProbeReturnsFalseOnEmptyStream(t *testing.T) {
	now := time.UnixMilli(2_000_000_000_000).UTC()
	probe, _, _ := newLagTestProbe(t, now)
	ctx := context.Background()

	age, ok, err := probe.OldestUnprocessedAge(ctx, "demo", "")
	require.NoError(t, err)
	require.False(t, ok)
	assert.Zero(t, age)
}

func formatEntryID(ms int64, seq int64) string {
	return strconv.FormatInt(ms, 10) + "-" + strconv.FormatInt(seq, 10)
}