package pipeline

import (
	"fmt"
	"sort"
	"strings"

	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
)

type InputAdapterConstructor func() (contracts.InputAdapter, error)

type InputAdapterRegistry struct {
	constructors map[string]InputAdapterConstructor
}

func NewInputAdapterRegistry() *InputAdapterRegistry {
	return &InputAdapterRegistry{
		constructors: make(map[string]InputAdapterConstructor),
	}
}

func (r *InputAdapterRegistry) Register(key string, constructor InputAdapterConstructor) error {
	if r == nil {
		return fmt.Errorf("input adapter registry must not be nil")
	}

	normalizedKey := strings.TrimSpace(key)
	if normalizedKey == "" {
		return fmt.Errorf("input adapter key must not be empty")
	}
	if constructor == nil {
		return fmt.Errorf("input adapter constructor for %q must not be nil", normalizedKey)
	}
	if _, ok := r.constructors[normalizedKey]; ok {
		return fmt.Errorf("input adapter %q is already registered", normalizedKey)
	}

	r.constructors[normalizedKey] = constructor
	return nil
}

func (r *InputAdapterRegistry) Build(key string) (contracts.InputAdapter, error) {
	if r == nil {
		return nil, fmt.Errorf("input adapter registry must not be nil")
	}

	normalizedKey := strings.TrimSpace(key)
	if normalizedKey == "" {
		return nil, fmt.Errorf("input adapter key must not be empty")
	}

	constructor, ok := r.constructors[normalizedKey]
	if !ok {
		return nil, fmt.Errorf("input adapter %q is not registered", normalizedKey)
	}

	adapter, err := constructor()
	if err != nil {
		return nil, fmt.Errorf("build input adapter %q: %w", normalizedKey, err)
	}
	if adapter == nil {
		return nil, fmt.Errorf("input adapter %q constructor returned nil", normalizedKey)
	}
	if adapter.Key() != normalizedKey {
		return nil, fmt.Errorf("input adapter %q returned key %q", normalizedKey, adapter.Key())
	}

	return adapter, nil
}

func (r *InputAdapterRegistry) RegisteredKeys() []string {
	if r == nil {
		return nil
	}

	keys := make([]string, 0, len(r.constructors))
	for key := range r.constructors {
		keys = append(keys, key)
	}
	sort.Strings(keys)
	return keys
}