//go:build linux || freebsd
// +build linux freebsd

package protocol

import (
	"fmt"
	"net/url"
	"sort"
	"strings"
	"sync"

	"codeberg.org/petrbalvin/goget/internal/core"
)

// Registry manages all registered protocols
type Registry struct {
	mu        sync.RWMutex
	protocols map[string]core.Protocol
}

// NewRegistry creates a new registry
func NewRegistry() *Registry {
	return &Registry{
		protocols: make(map[string]core.Protocol),
	}
}

// Register registers a protocol under its primary scheme
func (r *Registry) Register(p core.Protocol) error {
	r.mu.Lock()
	defer r.mu.Unlock()

	scheme := p.Scheme()
	if scheme == "" {
		return fmt.Errorf("protocol scheme cannot be empty")
	}

	if _, exists := r.protocols[scheme]; exists {
		return fmt.Errorf("protocol already registered: %s", scheme)
	}

	r.protocols[scheme] = p
	return nil
}

// normalizeScheme normalizes a scheme for lookup (https -> http, webdavs -> webdav, etc.)
func normalizeScheme(scheme string) string {
	scheme = strings.ToLower(scheme)
	switch scheme {
	case "https":
		return "http"
	case "webdavs":
		return "webdav"
	case "ftps":
		return "ftp"
	default:
		return scheme
	}
}

// Get gets a protocol for a given URL with scheme normalization
func (r *Registry) Get(u *url.URL) (core.Protocol, error) {
	r.mu.RLock()
	defer r.mu.RUnlock()

	if u == nil {
		return nil, fmt.Errorf("url cannot be nil")
	}

	scheme := normalizeScheme(u.Scheme)
	p, exists := r.protocols[scheme]
	if !exists {
		return nil, fmt.Errorf("unsupported protocol: %s", u.Scheme)
	}

	// Additional validation via CanHandle
	if !p.CanHandle(u) {
		return nil, fmt.Errorf("protocol %s cannot handle url: %s", scheme, u.String())
	}

	return p, nil
}

// List returns a list of all registered protocols
func (r *Registry) List() []string {
	r.mu.RLock()
	defer r.mu.RUnlock()

	schemes := make([]string, 0, len(r.protocols))
	for scheme := range r.protocols {
		schemes = append(schemes, scheme)
	}

	sort.Strings(schemes)
	return schemes
}

// Supports determines whether a protocol is supported (with normalization)
func (r *Registry) Supports(scheme string) bool {
	r.mu.RLock()
	defer r.mu.RUnlock()

	_, exists := r.protocols[normalizeScheme(scheme)]
	return exists
}

// Capabilities returns the capabilities of all protocols
func (r *Registry) Capabilities() map[string][]string {
	r.mu.RLock()
	defer r.mu.RUnlock()

	caps := make(map[string][]string)
	for scheme, p := range r.protocols {
		caps[scheme] = p.Capabilities()
	}

	return caps
}

// GlobalRegistry is the global registry instance
var GlobalRegistry = NewRegistry()

// Register is a helper for registering in the global registry
func Register(p core.Protocol) error {
	return GlobalRegistry.Register(p)
}

// Get is a helper for getting a protocol from the global registry
func Get(u *url.URL) (core.Protocol, error) {
	return GlobalRegistry.Get(u)
}