package domain

import (
	"context"
	"sync"
	"time"

	"gitea.nik4nao.com/nik/home-services/ai-gateway/internal/core/ports/driven"
)

// LightCache keeps recently-fetched light discovery data in memory.
type LightCache struct {
	ttl      time.Duration
	loadFunc func(context.Context) ([]driven.Light, error)

	mu       sync.RWMutex
	lights   []driven.Light
	loadedAt time.Time
}

// NewLightCache constructs a TTL-based in-memory light cache.
func NewLightCache(ttl time.Duration, loadFunc func(context.Context) ([]driven.Light, error)) *LightCache {
	return &LightCache{ttl: ttl, loadFunc: loadFunc}
}

// Get returns the cached lights, refreshing lazily when empty or stale.
func (c *LightCache) Get(ctx context.Context) ([]driven.Light, error) {
	c.mu.RLock()
	if len(c.lights) > 0 && time.Since(c.loadedAt) < c.ttl {
		lights := append([]driven.Light(nil), c.lights...)
		c.mu.RUnlock()
		return lights, nil
	}
	c.mu.RUnlock()

	c.mu.Lock()
	defer c.mu.Unlock()
	if len(c.lights) > 0 && time.Since(c.loadedAt) < c.ttl {
		return append([]driven.Light(nil), c.lights...), nil
	}

	lights, err := c.loadFunc(ctx)
	if err != nil {
		return nil, err
	}
	c.lights = append([]driven.Light(nil), lights...)
	c.loadedAt = time.Now()
	return append([]driven.Light(nil), c.lights...), nil
}