package sources

import (
	"fmt"
	"strings"

	"gitea.maximumdirect.net/ejr/feedkit/config"
)

// Factory constructs a configured Source instance from config.
//
// This is how concrete daemons (weatherfeeder/newsfeeder/...) register their
// domain-specific source drivers (Open-Meteo, NWS, RSS, etc.) while feedkit
// remains domain-agnostic.
type Factory func(cfg config.SourceConfig) (Source, error)
type StreamFactory func(cfg config.SourceConfig) (StreamSource, error)

type Registry struct {
	byDriver       map[string]Factory
	byStreamDriver map[string]StreamFactory
}

func NewRegistry() *Registry {
	return &Registry{
		byDriver:       map[string]Factory{},
		byStreamDriver: map[string]StreamFactory{},
	}
}

// Register associates a driver name (e.g. "openmeteo_observation") with a factory.
//
// The driver string is the "lookup key" used by config.sources[].driver.
func (r *Registry) Register(driver string, f Factory) {
	driver = strings.TrimSpace(driver)
	if driver == "" {
		// Panic is appropriate here: registering an empty driver is always a programmer error,
		// and it will lead to extremely confusing runtime behavior if allowed.
		panic("sources.Registry.Register: driver cannot be empty")
	}
	if f == nil {
		panic(fmt.Sprintf("sources.Registry.Register: factory cannot be nil (driver=%q)", driver))
	}
	if _, exists := r.byStreamDriver[driver]; exists {
		panic(fmt.Sprintf("sources.Registry.Register: driver %q already registered as a stream source", driver))
	}
	r.byDriver[driver] = f
}

// RegisterStream is the StreamSource equivalent of Register.
func (r *Registry) RegisterStream(driver string, f StreamFactory) {
	driver = strings.TrimSpace(driver)
	if driver == "" {
		panic("sources.Registry.RegisterStream: driver cannot be empty")
	}
	if f == nil {
		panic(fmt.Sprintf("sources.Registry.RegisterStream: factory cannot be nil (driver=%q)", driver))
	}
	if _, exists := r.byDriver[driver]; exists {
		panic(fmt.Sprintf("sources.Registry.RegisterStream: driver %q already registered as a polling source", driver))
	}
	r.byStreamDriver[driver] = f
}

// Build constructs a Source from a SourceConfig by looking up cfg.Driver.
func (r *Registry) Build(cfg config.SourceConfig) (Source, error) {
	f, ok := r.byDriver[cfg.Driver]
	if !ok {
		return nil, fmt.Errorf("unknown source driver: %q", cfg.Driver)
	}
	return f(cfg)
}

// BuildInput can return either a polling Source or a StreamSource.
func (r *Registry) BuildInput(cfg config.SourceConfig) (Input, error) {
	if f, ok := r.byStreamDriver[cfg.Driver]; ok {
		return f(cfg)
	}
	if f, ok := r.byDriver[cfg.Driver]; ok {
		return f(cfg)
	}
	return nil, fmt.Errorf("unknown source driver: %q", cfg.Driver)
}