package config

import (
	"context"
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/fsnotify/fsnotify"

	"git.daviestechlabs.io/daviestechlabs/ntfy-discord/internal/vault"
)

// Config holds the application configuration
type Config struct {
	NtfyURL     string
	NtfyTopics  []string
	SecretsPath string
	HTTPPort    string

	// Vault configuration
	VaultEnabled bool
	vaultClient  *vault.Client

	mu         sync.RWMutex
	webhookURL string
}

// Load creates a new Config from environment variables
func Load(ctx context.Context) (*Config, error) {
	cfg := &Config{
		NtfyURL:      getEnv("NTFY_URL", "http://ntfy.observability.svc.cluster.local"),
		SecretsPath:  getEnv("SECRETS_PATH", ""),
		HTTPPort:     getEnv("HTTP_PORT", "8080"),
		VaultEnabled: getEnv("VAULT_ENABLED", "false") == "true",
	}

	// Parse topics
	topics := getEnv("NTFY_TOPICS", "")
	if topics != "" {
		cfg.NtfyTopics = strings.Split(topics, ",")
		for i := range cfg.NtfyTopics {
			cfg.NtfyTopics[i] = strings.TrimSpace(cfg.NtfyTopics[i])
		}
	}

	// Try Vault first if enabled
	if cfg.VaultEnabled {
		if err := cfg.initVault(ctx); err != nil {
			slog.Warn("vault init failed, falling back to file/env", "error", err)
		} else {
			// Load webhook from Vault
			if webhookURL, err := cfg.vaultClient.GetSecret(ctx, "webhook-url"); err == nil {
				cfg.mu.Lock()
				cfg.webhookURL = webhookURL
				cfg.mu.Unlock()
				slog.Info("loaded webhook URL from vault")
			} else {
				slog.Warn("failed to get webhook from vault", "error", err)
			}
		}
	}

	// Fall back to file-based secret
	if cfg.webhookURL == "" && cfg.SecretsPath != "" {
		if err := cfg.loadWebhookFromSecret(); err != nil {
			slog.Warn("failed to load webhook from secret, trying env", "error", err)
		}
	}

	// Fall back to environment variable
	if cfg.webhookURL == "" {
		cfg.webhookURL = getEnv("DISCORD_WEBHOOK_URL", "")
	}

	if cfg.webhookURL == "" {
		slog.Warn("no Discord webhook URL configured")
	}

	slog.Info("config loaded",
		"ntfy_url", cfg.NtfyURL,
		"topics", cfg.NtfyTopics,
		"secrets_path", cfg.SecretsPath,
		"vault_enabled", cfg.VaultEnabled,
	)

	return cfg, nil
}

// initVault initializes the Vault client
func (c *Config) initVault(ctx context.Context) error {
	vaultCfg := vault.Config{
		Address:    getEnv("VAULT_ADDR", "http://vault.vault.svc.cluster.local:8200"),
		AuthMethod: getEnv("VAULT_AUTH_METHOD", "kubernetes"),
		Role:       getEnv("VAULT_ROLE", "ntfy-discord"),
		MountPath:  getEnv("VAULT_MOUNT_PATH", "secret"),
		SecretPath: getEnv("VAULT_SECRET_PATH", "ntfy-discord"),
		TokenPath:  getEnv("VAULT_TOKEN_PATH", ""),
	}

	client, err := vault.NewClient(vaultCfg)
	if err != nil {
		return err
	}

	c.vaultClient = client
	return nil
}

// WebhookURL returns the current webhook URL (thread-safe)
func (c *Config) WebhookURL() string {
	c.mu.RLock()
	defer c.mu.RUnlock()
	return c.webhookURL
}

// loadWebhookFromSecret reads the webhook URL from the mounted secret
func (c *Config) loadWebhookFromSecret() error {
	path := filepath.Join(c.SecretsPath, "webhook-url")
	data, err := os.ReadFile(path)
	if err != nil {
		return err
	}

	c.mu.Lock()
	c.webhookURL = strings.TrimSpace(string(data))
	c.mu.Unlock()

	slog.Debug("loaded webhook URL from secret")
	return nil
}

// WatchSecrets watches the secrets directory for changes and reloads
func (c *Config) WatchSecrets(ctx context.Context) {
	// Start Vault watcher if enabled
	if c.vaultClient != nil {
		go c.watchVaultSecrets(ctx)
	}

	// Start file watcher if secrets path is set
	if c.SecretsPath != "" {
		go c.watchFileSecrets(ctx)
	}
}

// watchVaultSecrets periodically refreshes secrets from Vault
func (c *Config) watchVaultSecrets(ctx context.Context) {
	interval := 30 * time.Second
	ticker := time.NewTicker(interval)
	defer ticker.Stop()

	slog.Info("watching vault secrets", "interval", interval)

	for {
		select {
		case <-ticker.C:
			if webhookURL, err := c.vaultClient.GetSecret(ctx, "webhook-url"); err == nil {
				c.mu.Lock()
				if c.webhookURL != webhookURL {
					c.webhookURL = webhookURL
					slog.Info("webhook URL updated from vault")
				}
				c.mu.Unlock()
			} else {
				slog.Error("failed to refresh webhook from vault", "error", err)
			}
		case <-ctx.Done():
			return
		}
	}
}

// watchFileSecrets watches the secrets directory for changes
func (c *Config) watchFileSecrets(ctx context.Context) {
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		slog.Error("failed to create fsnotify watcher", "error", err)
		return
	}
	defer func() { _ = watcher.Close() }()

	// Watch the secrets directory
	// Kubernetes updates secrets by changing the symlink, so watch the parent
	if err := watcher.Add(c.SecretsPath); err != nil {
		slog.Error("failed to watch secrets path", "error", err, "path", c.SecretsPath)
		return
	}

	slog.Info("watching secrets for changes", "path", c.SecretsPath)

	for {
		select {
		case event, ok := <-watcher.Events:
			if !ok {
				return
			}
			// Kubernetes updates secrets via symlink, which triggers Create events
			if event.Has(fsnotify.Create) || event.Has(fsnotify.Write) {
				slog.Info("secret changed, reloading", "event", event.Name)
				if err := c.loadWebhookFromSecret(); err != nil {
					slog.Error("failed to reload webhook from secret", "error", err)
				} else {
					slog.Info("webhook URL reloaded successfully")
				}
			}
		case err, ok := <-watcher.Errors:
			if !ok {
				return
			}
			slog.Error("fsnotify error", "error", err)
		case <-ctx.Done():
			return
		}
	}
}

// Close cleans up resources
func (c *Config) Close() error {
	if c.vaultClient != nil {
		return c.vaultClient.Close()
	}
	return nil
}

func getEnv(key, defaultVal string) string {
	if val := os.Getenv(key); val != "" {
		return val
	}
	return defaultVal
}