package models

import (
	"sync"

	"gorm.io/gorm"
)

// configCache holds process-level caches of platform configuration so that
// per-request rendering and upload validation do not hit the database. The
// cache is populated once at startup and refreshed whenever an admin saves a
// settings page (see RefreshConfigCache / the admin handlers).
var configCache = struct {
	mu       sync.RWMutex
	site     *SiteSetting
	upload   *UploadConfig
	types    []UploadFileType
	baseURLs []DownloadBaseURL
}{
	site:   &SiteSetting{},
	upload: &UploadConfig{Enabled: true, DefaultMaxSize: DefaultUploadMaxSize, StorageDir: "attachments"},
}

// LoadConfigCache reads all platform configuration from the database into the
// process cache. Called once at startup after InitDB.
func LoadConfigCache(db *gorm.DB) {
	configCache.mu.Lock()
	defer configCache.mu.Unlock()

	var s SiteSetting
	if err := db.First(&s, 1).Error; err == nil {
		configCache.site = &s
	} else {
		configCache.site = &SiteSetting{ID: 1}
	}

	var u UploadConfig
	if err := db.First(&u, 1).Error; err == nil {
		configCache.upload = &u
	} else {
		configCache.upload = &UploadConfig{ID: 1, Enabled: true, DefaultMaxSize: DefaultUploadMaxSize, StorageDir: "attachments"}
	}

	var t []UploadFileType
	if err := db.Order("sort asc, id asc").Find(&t).Error; err == nil {
		configCache.types = t
	}

	var b []DownloadBaseURL
	if err := db.Order("is_default desc, priority asc, id asc").Find(&b).Error; err == nil {
		configCache.baseURLs = b
	}
}

// RefreshConfigCache reloads all cached platform configuration. Admin handlers
// call this after writing changes so the next request sees them.
func RefreshConfigCache(db *gorm.DB) {
	LoadConfigCache(db)
}

// GetSiteSetting returns a pointer to the cached site settings (read-only copy
// semantics: callers must not mutate).
func GetSiteSetting() *SiteSetting {
	configCache.mu.RLock()
	defer configCache.mu.RUnlock()
	return configCache.site
}

// GetUploadConfig returns the cached upload policy.
func GetUploadConfig() *UploadConfig {
	configCache.mu.RLock()
	defer configCache.mu.RUnlock()
	return configCache.upload
}

// GetUploadFileTypes returns the cached list of permitted file types.
func GetUploadFileTypes() []UploadFileType {
	configCache.mu.RLock()
	defer configCache.mu.RUnlock()
	return configCache.types
}

// GetDownloadBaseURLs returns the cached list of download base URLs.
func GetDownloadBaseURLs() []DownloadBaseURL {
	configCache.mu.RLock()
	defer configCache.mu.RUnlock()
	return configCache.baseURLs
}

// DefaultDownloadBaseURL returns the base URL used to build attachment download
// links: the enabled row marked IsDefault, else the highest-priority enabled
// row. Returns an empty string if none is configured.
func DefaultDownloadBaseURL() string {
	configCache.mu.RLock()
	defer configCache.mu.RUnlock()

	// Rows are ordered is_default desc, priority asc, so the first enabled row
	// is the right pick.
	for _, b := range configCache.baseURLs {
		if b.Enabled {
			return b.BaseURL
		}
	}
	return ""
}