package store

import (
	"context"
	"testing"
	"time"

	"github.com/alicebob/miniredis/v2"
	"github.com/cosmic-clash/cosmic-clash/server/domain"
	"github.com/redis/go-redis/v9"
)

func TestCandidateProjectionRepairsPartialRedisStateFromDurableSource(t *testing.T) {
	mini, err := miniredis.Run()
	if err != nil {
		t.Fatal(err)
	}
	defer mini.Close()
	client := redis.NewClient(&redis.Options{Addr: mini.Addr()})
	defer client.Close()
	now := time.Unix(1000, 0).UTC()
	candidate := domain.Candidate{TicketID: "repair-ticket", PlayerID: "repair-player", EnqueuedAt: now}
	index := RedisCandidateIndex{Client: client, Prefix: "repair", TTL: time.Minute}
	_, orderKey := index.keys()
	if err := client.ZAdd(context.Background(), orderKey, redis.Z{Score: float64(now.UnixNano()), Member: candidate.TicketID}).Err(); err != nil {
		t.Fatal(err)
	}
	projection := CandidateProjection{Index: index, Source: func(context.Context, time.Time) ([]domain.Candidate, error) {
		return []domain.Candidate{candidate}, nil
	}}
	got, err := projection.Snapshot(context.Background(), now)
	if err != nil {
		t.Fatal(err)
	}
	if len(got) != 1 || got[0].TicketID != candidate.TicketID {
		t.Fatalf("repaired projection = %+v", got)
	}
}

func TestCandidateProjectionDoesNotReturnCacheWhenRepairSourceFails(t *testing.T) {
	index := RedisCandidateIndex{TTL: time.Minute}
	projection := CandidateProjection{Index: index, Source: func(context.Context, time.Time) ([]domain.Candidate, error) {
		return nil, context.DeadlineExceeded
	}}
	if _, err := projection.Snapshot(context.Background(), time.Unix(1000, 0)); err == nil {
		t.Fatal("cache projection succeeded without a usable Redis/index source")
	}
}

// TestCandidateProjectionFallsBackToSourceWhenRedisIsEntirelyUnreachable
// covers the gap multiplayer-next.md §8.46 named "live Redis failover":
// Redis is documented everywhere (RedisCandidateIndex's own comment,
// cmd/matcher, cmd/control-plane) as an optional, rebuildable acceleration
// layer over PostgreSQL authority. Before this fix, Snapshot funnelled a
// genuine Redis connection failure into the same Repair path as an empty
// cache -- but Repair's own Index.Rebuild call also needs Redis, so it failed
// for the identical reason, and Snapshot returned an error even though the
// authoritative Source was perfectly healthy. A real Redis outage or
// mid-failover window would have taken matchmaking down completely.
func TestCandidateProjectionFallsBackToSourceWhenRedisIsEntirelyUnreachable(t *testing.T) {
	mini, err := miniredis.Run()
	if err != nil {
		t.Fatal(err)
	}
	client := redis.NewClient(&redis.Options{Addr: mini.Addr()})
	defer client.Close()
	mini.Close() // Redis is now entirely unreachable, not merely empty or stale.

	now := time.Unix(1000, 0).UTC()
	candidate := domain.Candidate{TicketID: "down-ticket", PlayerID: "down-player", EnqueuedAt: now}
	sourceCalls := 0
	projection := CandidateProjection{
		Index: RedisCandidateIndex{Client: client, Prefix: "down", TTL: time.Minute},
		Source: func(context.Context, time.Time) ([]domain.Candidate, error) {
			sourceCalls++
			return []domain.Candidate{candidate}, nil
		},
	}
	got, err := projection.Snapshot(context.Background(), now)
	if err != nil {
		t.Fatalf("Snapshot failed while Redis was down, even though Source (PostgreSQL) was healthy: %v", err)
	}
	if len(got) != 1 || got[0].TicketID != candidate.TicketID {
		t.Fatalf("fallback snapshot = %+v, want the durable candidate served directly", got)
	}
	if sourceCalls != 1 {
		t.Fatalf("Source calls = %d, want exactly 1", sourceCalls)
	}
}

// TestCandidateProjectionStillFailsWhenBothRedisAndSourceAreDown proves the
// fallback isn't unconditional: if PostgreSQL itself is also unavailable,
// Snapshot must still fail rather than silently return an empty match pool.
func TestCandidateProjectionStillFailsWhenBothRedisAndSourceAreDown(t *testing.T) {
	mini, err := miniredis.Run()
	if err != nil {
		t.Fatal(err)
	}
	client := redis.NewClient(&redis.Options{Addr: mini.Addr()})
	defer client.Close()
	mini.Close()

	projection := CandidateProjection{
		Index: RedisCandidateIndex{Client: client, Prefix: "down", TTL: time.Minute},
		Source: func(context.Context, time.Time) ([]domain.Candidate, error) {
			return nil, context.DeadlineExceeded
		},
	}
	if _, err := projection.Snapshot(context.Background(), time.Unix(1000, 0)); err == nil {
		t.Fatal("Snapshot succeeded with both Redis and the durable source unavailable")
	}
}

func TestCandidateProjectionRepairsEmptyIndexFromDurableSource(t *testing.T) {
	mini, err := miniredis.Run()
	if err != nil {
		t.Fatal(err)
	}
	defer mini.Close()
	client := redis.NewClient(&redis.Options{Addr: mini.Addr()})
	defer client.Close()
	now := time.Unix(1000, 0).UTC()
	candidate := domain.Candidate{TicketID: "miss-ticket", PlayerID: "miss-player", EnqueuedAt: now}
	projection := CandidateProjection{
		Index: RedisCandidateIndex{Client: client, Prefix: "miss", TTL: time.Minute},
		Source: func(context.Context, time.Time) ([]domain.Candidate, error) {
			return []domain.Candidate{candidate}, nil
		},
	}
	got, err := projection.Snapshot(context.Background(), now)
	if err != nil {
		t.Fatal(err)
	}
	if len(got) != 1 || got[0].TicketID != candidate.TicketID {
		t.Fatalf("empty-index repair = %+v", got)
	}
}