package promptkit

import (
	"gitea.maximumdirect.net/eric/ConfigKit"
	"gitea.maximumdirect.net/eric/promptkit/internal/backend"
)

// BackendOpenRouter identifies the maintained OpenRouter backend.
const BackendOpenRouter = backend.OpenRouterID

// BackendRakestrawHome identifies the maintained Rakestrawhome backend.
const BackendRakestrawHome = backend.RakestrawHomeID

// BackendLocal is a conventional ID for a caller-configured local backend.
const BackendLocal = "local"

// BackendConfig is a presence-aware convenience value for a keyed backend
// definition. Nil pointer fields are omitted, while non-nil pointers preserve
// explicit zero or blank values. A nil ExtraParams map is omitted; a non-nil
// empty map supplies an empty mapping. Use raw ConfigKit Mapping inputs for
// explicit null. BackendConfig has no stable JSON representation.
type BackendConfig struct {
	// Endpoint is the required absolute HTTP(S) base URL after all layers merge.
	Endpoint *string
	// APIKeyEnv optionally names an environment variable, not a credential.
	APIKeyEnv *string
	// ConcurrencyLimit is zero for unlimited generation; negative is invalid.
	ConcurrencyLimit *int
	// QueueCapacity defaults to 1024 for positive concurrency when omitted.
	// An explicit value, including zero, requires positive concurrency.
	QueueCapacity *int
	// ExtraParams supplies JSON-compatible provider request defaults.
	ExtraParams map[string]any
}

// BackendSource creates a labeled ConfigKit mapping from keyed backend values.
// It encodes fields without validating them; NewEngine validates the final
// effective configuration after all selected source layers are combined.
// Mapping captures a copy of supported input values at creation; unsupported
// values fail when the source is loaded.
func BackendSource(label string, backends map[string]BackendConfig) configkit.Source {
	definitions := make(map[string]any, len(backends))
	for id, config := range backends {
		fields := make(map[string]any)
		if config.Endpoint != nil {
			fields["endpoint"] = *config.Endpoint
		}
		if config.APIKeyEnv != nil {
			fields["api_key_env"] = *config.APIKeyEnv
		}
		if config.ConcurrencyLimit != nil {
			fields["concurrency_limit"] = *config.ConcurrencyLimit
		}
		if config.QueueCapacity != nil {
			fields["queue_capacity"] = *config.QueueCapacity
		}
		if config.ExtraParams != nil {
			fields["extra_params"] = providerMapForMapping(config.ExtraParams)
		}
		definitions[id] = fields
	}
	return configkit.Mapping(label, map[string]any{"backends": definitions})
}

// LocalBackend supplies endpoint and concurrency pointers for a caller-chosen
// backend ID; it does not select an ID or validate either value.
func LocalBackend(endpoint string, concurrencyLimit int) BackendConfig {
	return BackendConfig{Endpoint: &endpoint, ConcurrencyLimit: &concurrencyLimit}
}