cache

type Config struct {
	// Store is the cache backend. Default: [NewMemoryStore].
	Store store.KV

	// TTL is the default cache entry lifetime. Default: 1 minute.
	// Per-response Cache-Control: max-age directives, when respected,
	// cap the effective TTL to min(TTL, max-age).
	TTL time.Duration

	// KeyGenerator derives the cache key from a request. When nil, the
	// default uses method + path + sorted query string + values of every
	// header listed in [VaryHeaders].
	KeyGenerator func(*celeris.Context) string

	// Singleflight coalesces concurrent cache-miss requests for the same
	// key so only one handler invocation runs; waiters reuse the
	// resulting response. Default: true.
	Singleflight bool

	// Methods lists HTTP methods eligible for caching. Default: GET, HEAD.
	// Methods not in this list pass through without interacting with
	// the cache.
	Methods []string

	// StatusFilter decides whether a computed response should be stored.
	// When nil, only 2xx responses are cached.
	StatusFilter func(status int) bool

	// VaryHeaders are included in the default cache key. Callers who
	// provide their own [KeyGenerator] can ignore this field.
	VaryHeaders []string

	// HeaderName is the response header populated with "HIT" or "MISS".
	// Default: "X-Cache". Set to "" to disable.
	HeaderName string

	// MaxBodyBytes caps the response body size eligible for caching.
	// Responses larger than this pass through uncached. Default: 1 MiB.
	MaxBodyBytes int

	// IncludeHeaders, when non-empty, whitelists response headers that
	// are stored alongside the body. When nil, all response headers
	// are stored except those in [ExcludeHeaders] (default: Set-Cookie).
	IncludeHeaders []string

	// ExcludeHeaders, when non-empty, is subtracted from the stored
	// header set after applying [IncludeHeaders]. Default: "set-cookie".
	ExcludeHeaders []string

	// RespectCacheControl, when true (default), honors the response's
	// Cache-Control directive:
	//   - no-store or private → skip caching
	//   - max-age=N           → cap TTL to min(cfg.TTL, N)
	RespectCacheControl bool

	// Skip defines a function to skip this middleware for certain
	// requests.
	Skip func(*celeris.Context) bool

	// SkipPaths lists paths to skip (exact match).
	SkipPaths []string
}

type MemoryStore struct {
	// contains filtered or unexported fields
}

type MemoryStoreConfig struct {
	// Shards is the number of lock shards. Default: runtime.NumCPU(),
	// rounded up to the next power of two.
	Shards int

	// MaxEntries is the total cache entry count across all shards.
	// Zero means unlimited. Per-shard capacity is MaxEntries/Shards
	// rounded up.
	MaxEntries int

	// CleanupInterval is how often expired entries are evicted.
	// Default: 1 minute.
	CleanupInterval time.Duration

	// CleanupContext, when set, stops the cleanup goroutine when the
	// context is cancelled.
	CleanupContext context.Context
}