package maintenance

import (
	"context"
	"sync"

	"evobgp/internal/store"
)

// ConfigProvider caches maintenance policies from store.Backend with hot reload.
type ConfigProvider struct {
	store store.Backend
	mu    sync.RWMutex
	items []*store.MaintenancePolicy
}

// NewConfigProvider constructs a provider; call Reload before use.
func NewConfigProvider(st store.Backend) *ConfigProvider {
	return &ConfigProvider{store: st}
}

// Reload loads all policies from the database into memory.
func (c *ConfigProvider) Reload(ctx context.Context) error {
	if c == nil || c.store == nil {
		return nil
	}
	_ = ctx
	items, _, _, err := c.store.ListMaintenancePolicies("", 1000)
	if err != nil {
		return err
	}
	cp := make([]*store.MaintenancePolicy, len(items))
	copy(cp, items)
	c.mu.Lock()
	c.items = cp
	c.mu.Unlock()
	return nil
}

// Snapshot returns a copy of cached policies.
func (c *ConfigProvider) Snapshot() []*store.MaintenancePolicy {
	if c == nil {
		return nil
	}
	c.mu.RLock()
	defer c.mu.RUnlock()
	out := make([]*store.MaintenancePolicy, len(c.items))
	copy(out, c.items)
	return out
}

// Get returns one policy by id from cache or store.
func (c *ConfigProvider) Get(ctx context.Context, id string) (*store.MaintenancePolicy, error) {
	if c == nil || c.store == nil {
		return nil, store.ErrNotFound
	}
	c.mu.RLock()
	for _, p := range c.items {
		if p.ID == id {
			cp := *p
			c.mu.RUnlock()
			return &cp, nil
		}
	}
	c.mu.RUnlock()
	return c.store.GetMaintenancePolicy(id)
}