package cache

import (
	"context"
	"fmt"
	"os"
	"testing"
	"time"
)

// TestDisabledFailsOpen verifies a Cache without a Redis backend never panics,
// always misses, and silently drops writes.
func TestDisabledFailsOpen(t *testing.T) {
	c := New("not-a-valid-url") // parse error => disabled
	if c.Enabled() {
		t.Fatal("expected cache to be disabled for invalid url")
	}
	c.SetJSON(context.Background(), "k", map[string]int{"a": 1}, time.Minute)
	var dst map[string]int
	if c.GetJSON(context.Background(), "k", &dst) {
		t.Fatalf("disabled cache must always miss, got %+v", dst)
	}
}

func testCache(t *testing.T) *Cache {
	t.Helper()
	url := os.Getenv("OPENGOODS_REDIS_URL")
	if url == "" {
		url = "redis://localhost:6379/0"
	}
	c := New(url)
	if !c.Enabled() {
		t.Skip("redis not configured")
	}
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	if err := c.rdb.Ping(ctx).Err(); err != nil {
		t.Skipf("redis not reachable: %v", err)
	}
	return c
}

// TestRoundTrip stores then reads a value back.
func TestRoundTrip(t *testing.T) {
	c := testCache(t)
	ctx := context.Background()
	suffix := fmt.Sprintf("test:rt:%d", time.Now().UnixNano())

	c.SetJSON(ctx, suffix, map[string]any{"name": "foo", "n": float64(3)}, time.Minute)
	got := map[string]any{}
	if !c.GetJSON(ctx, suffix, &got) {
		t.Fatal("expected cache hit after set")
	}
	if got["name"] != "foo" || got["n"] != float64(3) {
		t.Fatalf("unexpected payload: %+v", got)
	}
}

// TestEpochInvalidation verifies that bumping the epoch counter logically drops
// every previously cached entry.
func TestEpochInvalidation(t *testing.T) {
	c := testCache(t)
	ctx := context.Background()
	suffix := fmt.Sprintf("test:epoch:%d", time.Now().UnixNano())

	c.SetJSON(ctx, suffix, map[string]int{"v": 1}, time.Minute)
	var dst map[string]int
	if !c.GetJSON(ctx, suffix, &dst) {
		t.Fatal("expected hit before epoch bump")
	}

	// Simulate an ingestion write bumping the global epoch.
	if err := c.rdb.Incr(ctx, epochKey).Err(); err != nil {
		t.Fatalf("incr epoch: %v", err)
	}
	// Force the process to re-read the epoch rather than use its cached value.
	c.mu.Lock()
	c.epochOK = false
	c.mu.Unlock()

	if c.GetJSON(ctx, suffix, &dst) {
		t.Fatal("entry should be invisible after epoch bump")
	}
}