package protocol

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"sync"
)

type MethodEntry struct {
	Name string `json:"name"`
	ID   uint32 `json:"id"`
	Hex  string `json:"hex"`
}

type MethodIdCatalog struct {
	ClientBuild uint32        `json:"clientBuild"`
	Source      string        `json:"source"`
	Methods     []MethodEntry `json:"methods"`
}

var (
	methodRegistryLock sync.RWMutex
	idToNameMap        = make(map[uint32]string)
	nameToIdMap        = make(map[string]uint32)
	isRegistryLoaded   bool
)

func init() {
	for name, id := range canonicalMethodIDs {
		nameToIdMap[name] = id
		idToNameMap[id] = name
	}
}

// LoadMethodCatalog loads the method catalog from a JSON file (e.g. data/client_data/MethodIds.json).
func LoadMethodCatalog(path string) error {
	data, err := os.ReadFile(path)
	if err != nil {
		return fmt.Errorf("failed to read method catalog from %s: %w", path, err)
	}

	var catalog MethodIdCatalog
	if err := json.Unmarshal(data, &catalog); err != nil {
		return fmt.Errorf("failed to parse method catalog JSON: %w", err)
	}

	methodRegistryLock.Lock()
	defer methodRegistryLock.Unlock()

	for _, m := range catalog.Methods {
		idToNameMap[m.ID] = m.Name
		nameToIdMap[m.Name] = m.ID
	}
	isRegistryLoaded = true

	log.Printf("[PROTOCOL] Loaded %d RPC method definitions from %s (Build %d)", len(catalog.Methods), path, catalog.ClientBuild)
	return nil
}

// GetMethodName returns the friendly name of a Method ID, or a formatted fallback.
func GetMethodName(id uint32) string {
	methodRegistryLock.RLock()
	defer methodRegistryLock.RUnlock()

	if name, ok := idToNameMap[id]; ok {
		return name
	}
	return fmt.Sprintf("UnknownMethod_0x%08X(%d)", id, id)
}

// GetMethodID returns the numeric ID for a method name.
func GetMethodID(name string) (uint32, bool) {
	methodRegistryLock.RLock()
	defer methodRegistryLock.RUnlock()

	id, ok := nameToIdMap[name]
	return id, ok
}

// MethodGetMethodIDDefault resolves a verified name. Legacy callers still pass
// a fallback, but guessed IDs must never be sent to an unrelated client handler.
func MethodGetMethodIDDefault(name string, fallback uint32) uint32 {
	if id, ok := GetMethodID(name); ok {
		return id
	}
	return 0
}