package game

import "sync"

// FlagChangeCallback is invoked when a world flag value actually changes
// (old value differs from new, or new flag is created with a truthy value).
type FlagChangeCallback func(name string, value any)

// FlagStore holds world flags — shared mutable state visible to all players
// (e.g. opened doors, quest state). Player-specific flags live on
// *player.Player.Flags instead. FlagStore is safe for concurrent use.
type FlagStore struct {
	mu        sync.Mutex
	flags     map[string]any
	callbacks []FlagChangeCallback
}

func NewFlagStore() *FlagStore {
	return &FlagStore{flags: make(map[string]any)}
}

func (f *FlagStore) OnChange(cb FlagChangeCallback) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.callbacks = append(f.callbacks, cb)
}

func (f *FlagStore) Get(name string) (any, bool) {
	f.mu.Lock()
	defer f.mu.Unlock()
	v, ok := f.flags[name]
	return v, ok
}

func (f *FlagStore) Set(name string, value any) {
	f.mu.Lock()
	old, existed := f.flags[name]
	f.flags[name] = value
	cbs := f.callbacks
	f.mu.Unlock()

	if !existed || !valuesEqual(old, value) {
		for _, cb := range cbs {
			cb(name, value)
		}
	}
}

func (f *FlagStore) SetAll(m map[string]any) {
	f.mu.Lock()
	changed := make(map[string]any)
	for k, v := range m {
		old, existed := f.flags[k]
		f.flags[k] = v
		if !existed || !valuesEqual(old, v) {
			changed[k] = v
		}
	}
	cbs := f.callbacks
	f.mu.Unlock()

	for k, v := range changed {
		for _, cb := range cbs {
			cb(k, v)
		}
	}
}

func (f *FlagStore) Delete(name string) {
	f.mu.Lock()
	defer f.mu.Unlock()
	delete(f.flags, name)
}

func (f *FlagStore) All() map[string]any {
	f.mu.Lock()
	defer f.mu.Unlock()
	out := make(map[string]any, len(f.flags))
	for k, v := range f.flags {
		out[k] = v
	}
	return out
}