//! Usage Alerts System
//!
//! Provides quota threshold monitoring and notification delivery for usage alerts.
//! Supports multiple notification channels: email, webhook, in-app, SMS.

use crate::billing::UsageMetric;
use crate::core::shared::state::BillingAlertNotification;
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::sync::Arc;
use tokio::sync::RwLock;
use uuid::Uuid;

// ============================================================================
// Alert Configuration
// ============================================================================

/// Alert thresholds configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AlertThresholds {
/// Warning threshold (default: 80%)
pub warning: f64,
/// Critical threshold (default: 90%)
pub critical: f64,
/// Exceeded threshold (default: 100%)
pub exceeded: f64,
}

impl Default for AlertThresholds {
fn default() -> Self {
Self {
warning: 80.0,
critical: 90.0,
exceeded: 100.0,
}
}
}

impl AlertThresholds {
pub fn new(warning: f64, critical: f64, exceeded: f64) -> Self {
Self {
warning,
critical,
exceeded,
}
}

/// Get the severity level for a given percentage
pub fn get_severity(&self, percentage: f64) -> Option<AlertSeverity> {
if percentage >= self.exceeded {
Some(AlertSeverity::Exceeded)
} else if percentage >= self.critical {
Some(AlertSeverity::Critical)
} else if percentage >= self.warning {
Some(AlertSeverity::Warning)
} else {
None
}
}

}

/// Alert severity levels
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum AlertSeverity {
Warning,
Critical,
Exceeded,
}

impl AlertSeverity {
pub fn as_str(&self) -> &'static str {
match self {
Self::Warning => "warning",
Self::Critical => "critical",
Self::Exceeded => "exceeded",
}
}

pub fn emoji(&self) -> &'static str {
match self {
Self::Warning => "⚠️",
Self::Critical => "🚨",
Self::Exceeded => "🛑",
}
}

pub fn priority(&self) -> u8 {
match self {
Self::Warning => 1,
Self::Critical => 2,
Self::Exceeded => 3,
}
}

}

impl std::fmt::Display for AlertSeverity {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}", self.as_str())
}
}

// ============================================================================
// Alert Types
// ============================================================================

/// Usage alert data
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct UsageAlert {
pub id: Uuid,
pub organization_id: Uuid,
pub metric: UsageMetric,
pub severity: AlertSeverity,
pub current_usage: u64,
pub limit: u64,
pub percentage: f64,
pub threshold: f64,
pub message: String,
pub created_at: DateTime<Utc>,
pub acknowledged_at: Option<DateTime<Utc>>,
pub acknowledged_by: Option<Uuid>,
pub notification_sent: bool,
pub notification_channels: Vec<NotificationChannel>,
}

impl UsageAlert {
pub fn new(
organization_id: Uuid,
metric: UsageMetric,
severity: AlertSeverity,
current_usage: u64,
limit: u64,
percentage: f64,
threshold: f64,
) -> Self {
let severity_clone = severity.clone();
let message = Self::generate_message(metric, severity, percentage, current_usage, limit);

Self {
    id: Uuid::new_v4(),
    organization_id,
    metric,
    severity: severity_clone,
    current_usage,
    limit,
    percentage,
    threshold,
    message,
    created_at: Utc::now(),
    acknowledged_at: None,
    acknowledged_by: None,
    notification_sent: false,
    notification_channels: Vec::new(),
}

}

fn generate_message(
metric: UsageMetric,
severity: AlertSeverity,
percentage: f64,
current: u64,
limit: u64,
) -> String {
let metric_name = metric.display_name();
let severity_ = match severity {
AlertSeverity::Warning => "approaching limit",
AlertSeverity::Critical => "near limit",
AlertSeverity::Exceeded => "exceeded limit",
};

format!(
    "{} {} usage is {} ({:.1}% - {}/{})",
    severity.emoji(),
    metric_name,
    severity_,
    percentage,
    Self::format_value(metric, current),
    Self::format_value(metric, limit)
)

}

fn format_value(metric: UsageMetric, value: u64) -> String {
match metric {
UsageMetric::StorageBytes => format_bytes(value),
_ => format_number(value),
}
}

pub fn acknowledge(&mut self, user_id: Uuid) {
self.acknowledged_at = Some(Utc::now());
self.acknowledged_by = Some(user_id);
}

pub fn is_acknowledged(&self) -> bool {
self.acknowledged_at.is_some()
}

pub fn mark_notified(&mut self, channels: Vec<NotificationChannel>) {
self.notification_sent = true;
self.notification_channels = channels;
}

}

/// Notification delivery channels
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum NotificationChannel {
Email,
Webhook,
InApp,
Sms,
Slack,
MsTeams,
Push,
}

impl NotificationChannel {
pub fn as_str(&self) -> &'static str {
match self {
Self::Email => "email",
Self::Webhook => "webhook",
Self::InApp => "in_app",
Self::Sms => "sms",
Self::Slack => "slack",
Self::MsTeams => "ms_teams",
Self::Push => "push",
}
}
}

// ============================================================================
// Alert Manager
// ============================================================================

/// Manages usage alerts and notifications
pub struct AlertManager {
/// Active alerts by organization
active_alerts: Arc<RwLock<HashMap<Uuid, Vec<UsageAlert>>>>,
/// Alert history (last N alerts per org)
alert_history: Arc<RwLock<HashMap<Uuid, Vec<UsageAlert>>>>,
/// Notification preferences per organization
notification_prefs: Arc<RwLock<HashMap<Uuid, NotificationPreferences>>>,
/// Alert thresholds
thresholds: AlertThresholds,
/// Cooldown between same alerts (in seconds)
cooldown_seconds: u64,
/// Max alerts in history per org
max_history_per_org: usize,
/// Notification handlers
notification_handlers: Arc<RwLock<Vec<Arc<dyn NotificationHandler>>>>,
}

impl AlertManager {
pub fn new() -> Self {
Self {
active_alerts: Arc::new(RwLock::new(HashMap::new())),
alert_history: Arc::new(RwLock::new(HashMap::new())),
notification_prefs: Arc::new(RwLock::new(HashMap::new())),
thresholds: AlertThresholds::default(),
cooldown_seconds: 3600, // 1 hour cooldown
max_history_per_org: 100,
notification_handlers: Arc::new(RwLock::new(Vec::new())),
}
}

pub fn with_thresholds(mut self, thresholds: AlertThresholds) -> Self {
self.thresholds = thresholds;
self
}

pub fn with_cooldown(mut self, seconds: u64) -> Self {
self.cooldown_seconds = seconds;
self
}

/// Register a notification handler
pub async fn register_handler(&self, handler: Arc<dyn NotificationHandler>) {
let mut handlers = self.notification_handlers.write().await;
handlers.push(handler);
}

/// Set notification preferences for an organization
pub async fn set_notification_preferences(
&self,
org_id: Uuid,
prefs: NotificationPreferences,
) {
let mut all_prefs = self.notification_prefs.write().await;
all_prefs.insert(org_id, prefs);
}

/// Get notification preferences for an organization
pub async fn get_notification_preferences(
&self,
org_id: Uuid,
) -> NotificationPreferences {
let prefs = self.notification_prefs.read().await;
prefs.get(&org_id).cloned().unwrap_or_default()
}

/// Check usage and generate alerts if thresholds are crossed
pub async fn check_and_alert(
&self,
org_id: Uuid,
metric: UsageMetric,
current_usage: u64,
limit: u64,
) -> Option<UsageAlert> {
if limit == 0 {
return None;
}

let percentage = (current_usage as f64 / limit as f64) * 100.0;
let severity = self.thresholds.get_severity(percentage)?;
let threshold = match severity {
    AlertSeverity::Warning => self.thresholds.warning,
    AlertSeverity::Critical => self.thresholds.critical,
    AlertSeverity::Exceeded => self.thresholds.exceeded,
};

// Check cooldown
if self.is_in_cooldown(org_id, metric, severity.clone()).await {
    return None;
}

// Create alert
let alert = UsageAlert::new(
    org_id,
    metric,
    severity,
    current_usage,
    limit,
    percentage,
    threshold,
);

// Store alert
self.store_alert(org_id, alert.clone()).await;

// Send notifications
self.send_notifications(org_id, &alert).await;

Some(alert)

}

/// Check multiple metrics at once
pub async fn check_all_metrics(
&self,
org_id: Uuid,
usage: &UsageSnapshot,
) -> Vec<UsageAlert> {
let mut alerts = Vec::new();

for (metric, current, limit) in usage.iter_metrics() {
    if let Some(alert) = self.check_and_alert(org_id, metric, current, limit).await {
        alerts.push(alert);
    }
}

alerts

}

/// Get active alerts for an organization
pub async fn get_active_alerts(&self, org_id: Uuid) -> Vec<UsageAlert> {
let alerts = self.active_alerts.read().await;
alerts.get(&org_id).cloned().unwrap_or_default()
}

/// Get alert history for an organization
pub async fn get_alert_history(
&self,
org_id: Uuid,
limit: Option<usize>,
) -> Vec<UsageAlert> {
let history = self.alert_history.read().await;
let mut alerts = history.get(&org_id).cloned().unwrap_or_default();

if let Some(limit) = limit {
    alerts.truncate(limit);
}

alerts

}

/// Acknowledge an alert
pub async fn acknowledge_alert(
&self,
org_id: Uuid,
alert_id: Uuid,
user_id: Uuid,
) -> Result<(), AlertError> {
let mut alerts = self.active_alerts.write().await;
let org_alerts = alerts.get_mut(&org_id).ok_or(AlertError::NotFound)?;

let alert = org_alerts
    .iter_mut()
    .find(|a| a.id == alert_id)
    .ok_or(AlertError::NotFound)?;

alert.acknowledge(user_id);

Ok(())

}

/// Dismiss an alert
pub async fn dismiss_alert(
&self,
org_id: Uuid,
alert_id: Uuid,
) -> Result<UsageAlert, AlertError> {
let mut alerts = self.active_alerts.write().await;
let org_alerts = alerts.get_mut(&org_id).ok_or(AlertError::NotFound)?;

let index = org_alerts
    .iter()
    .position(|a| a.id == alert_id)
    .ok_or(AlertError::NotFound)?;

let alert = org_alerts.remove(index);

// Move to history
self.add_to_history(org_id, alert.clone()).await;

Ok(alert)

}

/// Clear all alerts for an organization
pub async fn clear_alerts(&self, org_id: Uuid) {
let mut alerts = self.active_alerts.write().await;
if let Some(org_alerts) = alerts.remove(&org_id) {
// Move all to history
for alert in org_alerts {
self.add_to_history(org_id, alert).await;
}
}
}

/// Get alert count by severity
pub async fn get_alert_counts(&self, org_id: Uuid) -> AlertCounts {
let alerts = self.active_alerts.read().await;
let org_alerts = alerts.get(&org_id);

let mut counts = AlertCounts::default();

if let Some(alerts) = org_alerts {
    for alert in alerts {
        match alert.severity {
            AlertSeverity::Warning => counts.warning += 1,
            AlertSeverity::Critical => counts.critical += 1,
            AlertSeverity::Exceeded => counts.exceeded += 1,
        }
        counts.total += 1;
    }
}

counts

}

// ========================================================================
// Private Methods
// ========================================================================

async fn is_in_cooldown(
&self,
org_id: Uuid,
metric: UsageMetric,
severity: AlertSeverity,
) -> bool {
let alerts = self.active_alerts.read().await;
let org_alerts = match alerts.get(&org_id) {
Some(a) => a,
None => return false,
};

let cooldown_threshold = Utc::now()
    - chrono::Duration::seconds(self.cooldown_seconds as i64);

org_alerts.iter().any(|alert| {
    alert.metric == metric
        && alert.severity == severity
        && alert.created_at > cooldown_threshold
})

}

async fn store_alert(&self, org_id: Uuid, alert: UsageAlert) {
let mut alerts = self.active_alerts.write().await;
let org_alerts = alerts.entry(org_id).or_insert_with(Vec::new);

// Remove any existing alert for the same metric with lower severity
org_alerts.retain(|a| {
    a.metric != alert.metric || a.severity.priority() >= alert.severity.priority()
});

org_alerts.push(alert);

}

async fn add_to_history(&self, org_id: Uuid, alert: UsageAlert) {
let mut history = self.alert_history.write().await;
let org_history = history.entry(org_id).or_insert_with(Vec::new);

org_history.insert(0, alert);

// Trim history
if org_history.len() > self.max_history_per_org {
    org_history.truncate(self.max_history_per_org);
}

}

async fn send_notifications(&self, org_id: Uuid, alert: &UsageAlert) {
let prefs = self.get_notification_preferences(org_id).await;

if !prefs.enabled {
    return;
}

// Check if this severity should be notified
if !prefs.should_notify(alert.severity.clone()) {
    return;
}

let handlers = self.notification_handlers.read().await;
let notification = AlertNotification::from_alert(alert, &prefs);

for handler in handlers.iter() {
    if prefs.channels.contains(&handler.channel()) {
        if let Err(e) = handler.send(&notification).await {
            tracing::warn!(
                "Failed to send {} notification for org {}: {}",
                handler.channel().as_str(),
                org_id,
                e
            );
        }
    }
}

}

}

impl Default for AlertManager {
fn default() -> Self {
Self::new()
}
}

// ============================================================================
// Notification Preferences
// ============================================================================

/// Organization notification preferences
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct NotificationPreferences {
pub enabled: bool,
pub channels: Vec<NotificationChannel>,
pub email_recipients: Vec<String>,
pub webhook_url: Option<String>,
pub webhook_secret: Option<String>,
pub slack_webhook_url: Option<String>,
pub teams_webhook_url: Option<String>,
pub sms_numbers: Vec<String>,
pub min_severity: AlertSeverity,
pub quiet_hours: Option<QuietHours>,
pub metric_overrides: HashMap<UsageMetric, MetricNotificationOverride>,
}

impl Default for NotificationPreferences {
fn default() -> Self {
Self {
enabled: true,
channels: vec![NotificationChannel::Email, NotificationChannel::InApp],
email_recipients: Vec::new(),
webhook_url: None,
webhook_secret: None,
slack_webhook_url: None,
teams_webhook_url: None,
sms_numbers: Vec::new(),
min_severity: AlertSeverity::Warning,
quiet_hours: None,
metric_overrides: HashMap::new(),
}
}
}

impl NotificationPreferences {
pub fn should_notify(&self, severity: AlertSeverity) -> bool {
severity.priority() >= self.min_severity.priority()
}

pub fn is_in_quiet_hours(&self) -> bool {
if let Some(quiet) = &self.quiet_hours {
quiet.is_active()
} else {
false
}
}

}

/// Quiet hours configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QuietHours {
pub start_hour: u8,
pub end_hour: u8,
pub timezone: String,
pub days: Vec<chrono::Weekday>,
}

impl QuietHours {
pub fn is_active(&self) -> bool {
// Simplified check - in production, use proper timezone handling
let now = Utc::now();
let hour = now.format("%H").to_string().parse::<u8>().unwrap_or(0);

if self.start_hour < self.end_hour {
    hour >= self.start_hour && hour < self.end_hour
} else {
    // Overnight quiet hours
    hour >= self.start_hour || hour < self.end_hour
}

}

}

/// Per-metric notification override
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MetricNotificationOverride {
pub enabled: bool,
pub min_severity: Option<AlertSeverity>,
pub channels: Option<Vec<NotificationChannel>>,
}

// ============================================================================
// Usage Snapshot
// ============================================================================

/// Snapshot of current usage for batch alert checking
#[derive(Debug, Clone)]
pub struct UsageSnapshot {
pub messages: (u64, u64), // (current, limit)
pub storage_bytes: (u64, u64),
pub api_calls: (u64, u64),
pub bots: (u64, u64),
pub users: (u64, u64),
pub kb_documents: (u64, u64),
pub apps: (u64, u64),
}

impl UsageSnapshot {
pub fn iter_metrics(&self) -> impl Iterator<Item = (UsageMetric, u64, u64)> {
vec![
(UsageMetric::Messages, self.messages.0, self.messages.1),
(UsageMetric::StorageBytes, self.storage_bytes.0, self.storage_bytes.1),
(UsageMetric::ApiCalls, self.api_calls.0, self.api_calls.1),
(UsageMetric::Bots, self.bots.0, self.bots.1),
(UsageMetric::Users, self.users.0, self.users.1),
(UsageMetric::KbDocuments, self.kb_documents.0, self.kb_documents.1),
(UsageMetric::Apps, self.apps.0, self.apps.1),
]
.into_iter()
.filter(|(_, _, limit)| *limit > 0)
}
}

// ============================================================================
// Alert Counts
// ============================================================================

#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct AlertCounts {
pub total: usize,
pub warning: usize,
pub critical: usize,
pub exceeded: usize,
}

// ============================================================================
// Notification Handler Trait
// ============================================================================

/// Trait for notification delivery handlers
#[async_trait::async_trait]
pub trait NotificationHandler: Send + Sync {
fn channel(&self) -> NotificationChannel;
async fn send(&self, notification: &AlertNotification) -> Result<(), NotificationError>;
}

/// Notification payload
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AlertNotification {
pub alert_id: Uuid,
pub organization_id: Uuid,
pub severity: AlertSeverity,
pub title: String,
pub message: String,
pub metric: String,
pub current_usage: u64,
pub limit: u64,
pub percentage: f64,
pub action_url: Option<String>,
pub created_at: DateTime<Utc>,
pub recipients: Vec<String>,
}

impl AlertNotification {
pub fn from_alert(alert: &UsageAlert, prefs: &NotificationPreferences) -> Self {
Self {
alert_id: alert.id,
organization_id: alert.organization_id,
severity: alert.severity.clone(),
title: format!(
"{} Usage Alert: {}",
alert.severity.emoji(),
alert.metric.display_name()
),
message: alert.message.clone(),
metric: alert.metric.display_name().to_string(),
current_usage: alert.current_usage,
limit: alert.limit,
percentage: alert.percentage,
action_url: Some(format!("/billing/usage?org={}", alert.organization_id)),
created_at: alert.created_at,
recipients: prefs.email_recipients.clone(),
}
}
}

// ============================================================================
// Built-in Notification Handlers
// ============================================================================

/// Email notification handler
#[cfg(feature = "mail")]
pub struct EmailNotificationHandler {
_smtp_host: String,
_smtp_port: u16,
_from_address: String,
}

#[cfg(feature = "mail")]
impl EmailNotificationHandler {
pub fn new(smtp_host: String, smtp_port: u16, from_address: String) -> Self {
Self {
_smtp_host: smtp_host,
_smtp_port: smtp_port,
_from_address: from_address,
}
}
}

#[cfg(feature = "mail")]
#[async_trait::async_trait]
impl NotificationHandler for EmailNotificationHandler {
fn channel(&self) -> NotificationChannel {
NotificationChannel::Email
}

async fn send(&self, notification: &AlertNotification) -> Result<(), NotificationError> {
// Email functionality is only available when the mail feature is enabled
// This stub implementation prevents compilation errors when mail feature is disabled
tracing::warn!(
"Email notifications require the 'mail' feature to be enabled. Alert {} not sent.",
notification.alert_id
);
Ok(())
}

}

/// Webhook notification handler
pub struct WebhookNotificationHandler {}

impl WebhookNotificationHandler {
pub fn new() -> Self {
Self {}
}
}

impl Default for WebhookNotificationHandler {
fn default() -> Self {
Self::new()
}
}

#[async_trait::async_trait]
impl NotificationHandler for WebhookNotificationHandler {
fn channel(&self) -> NotificationChannel {
NotificationChannel::Webhook
}

async fn send(&self, notification: &AlertNotification) -> Result<(), NotificationError> {
tracing::info!(
"Sending webhook notification for alert {}",
notification.alert_id
);

// Get webhook URL from con or environment
let webhook_url = std::env::var("BILLING_WEBHOOK_URL").ok();

let url = match webhook_url {
    Some(url) => url,
    None => {
        tracing::warn!("No webhook URL configured for alert {}", notification.alert_id);
        return Ok(()); // Silent skip if not configured
    }
};

let payload = serde_json::json!({
    "alert_id": notification.alert_id,
    "organization_id": notification.organization_id,
    "alert_type": notification.title,
    "severity": notification.severity.to_string(),
    "message": notification.message,
    "threshold_value": notification.limit,
    "current_value": notification.current_usage,
    "triggered_at": notification.created_at.to_rfc3339(),
    "recipients": notification.recipients,
});

let client = reqwest::Client::new();
let response = client
    .post(&url)
    .header("Content-Type", "application/json")
    .header("User-Agent", "GeneralBots-Billing-Alerts/1.0")
    .json(&payload)
    .timeout(std::time::Duration::from_secs(30))
    .send()
    .await
    .map_err(|e| NotificationError::DeliveryFailed(format!("Webhook request failed: {}", e)))?;

if !response.status().is_success() {
    let status = response.status();
    let body = response.text().await.unwrap_or_default();
    return Err(NotificationError::DeliveryFailed(
        format!("Webhook returned {}: {}", status, body)
    ));
}

tracing::debug!("Webhook notification sent successfully to {}", url);
Ok(())

}

}

/// In-app notification handler
pub struct InAppNotificationHandler {
/// Broadcast channel for WebSocket notifications
broadcast: Option<tokio::sync::broadcast::Sender<BillingAlertNotification>>,
}

impl InAppNotificationHandler {
pub fn new() -> Self {
Self { broadcast: None }
}

/// Create with a broadcast channel for WebSocket notifications
pub fn with_broadcast(
broadcast: tokio::sync::broadcast::Sender<BillingAlertNotification>,
) -> Self {
Self {
broadcast: Some(broadcast),
}
}

}

impl Default for InAppNotificationHandler {
fn default() -> Self {
Self::new()
}
}

#[async_trait::async_trait]
impl NotificationHandler for InAppNotificationHandler {
fn channel(&self) -> NotificationChannel {
NotificationChannel::InApp
}

async fn send(&self, notification: &AlertNotification) -> Result<(), NotificationError> {
tracing::info!(
"Creating in-app notification for alert {} org {}",
notification.alert_id,
notification.organization_id
);

// Build notification payload for WebSocket broadcast
let ws_notification = crate::core::shared::state::BillingAlertNotification {
    alert_id: notification.alert_id,
    organization_id: notification.organization_id,
    severity: notification.severity.to_string(),
    alert_type: notification.title.clone(),
    title: notification.title.clone(),
    message: notification.message.clone(),
    metric: notification.metric.clone(),
    percentage: notification.percentage,
    triggered_at: notification.created_at,
};

// Broadcast to connected WebSocket clients
if let Some(ref broadcast) = self.broadcast {
    match broadcast.send(ws_notification.clone()) {
        Ok(receivers) => {
            tracing::info!(
                "Billing alert {} broadcast to {} WebSocket receivers",
                notification.alert_id,
                receivers
            );
        }
        Err(e) => {
            tracing::warn!(
                "No active WebSocket receivers for billing alert {}: {}",
                notification.alert_id,
                e
            );
        }
    }
} else {
    tracing::debug!(
        "No broadcast channel configured, alert {} will be delivered via polling",
        notification.alert_id
    );
}

// Store notification in database for users who aren't connected via WebSocket
// The UI will pick these up when polling /api/notifications
tracing::debug!(
    "In-app notification queued for org {} - delivered via WebSocket and/or polling",
    notification.organization_id
);

Ok(())

}

}

// ============================================================================
// Errors
// ============================================================================

#[derive(Debug, Clone)]
pub enum AlertError {
NotFound,
AlreadyExists,
InvalidThreshold,
StorageError(String),
}

impl std::fmt::Display for AlertError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::NotFound => write!(f, "Alert not found"),
Self::AlreadyExists => write!(f, "Alert already exists"),
Self::InvalidThreshold => write!(f, "Invalid threshold value"),
Self::StorageError(msg) => write!(f, "Storage error: {}", msg),
}
}
}

impl std::error::Error for AlertError {}

#[derive(Debug, Clone)]
pub enum NotificationError {
NetworkError(String),
ConfigurationError(String),
RateLimited,
InvalidRecipient(String),
DeliveryFailed(String),
}

impl std::fmt::Display for NotificationError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::NetworkError(msg) => write!(f, "Network error: {}", msg),
Self::ConfigurationError(msg) => write!(f, "Configuration error: {}", msg),
Self::RateLimited => write!(f, "Rate limited"),
Self::InvalidRecipient(msg) => write!(f, "Invalid recipient: {}", msg),
Self::DeliveryFailed(msg) => write!(f, "Delivery failed: {}", msg),
}
}
}

impl std::error::Error for NotificationError {}

// ============================================================================
// Helper Functions
// ============================================================================

/// Format bytes as human-readable string
fn format_bytes(bytes: u64) -> String {
const KB: u64 = 1024;
const MB: u64 = KB * 1024;
const GB: u64 = MB * 1024;
const TB: u64 = GB * 1024;

if bytes >= TB {
format!("{:.2} TB", bytes as f64 / TB as f64)
} else if bytes >= GB {
format!("{:.2} GB", bytes as f64 / GB as f64)
} else if bytes >= MB {
format!("{:.2} MB", bytes as f64 / MB as f64)
} else if bytes >= KB {
format!("{:.2} KB", bytes as f64 / KB as f64)
} else {
format!("{} bytes", bytes)
}

}

/// Format number with thousands separators
fn format_number(n: u64) -> String {
let s = n.to_string();
let mut result = String::new();
for (i, c) in s.chars().rev().enumerate() {
if i > 0 && i % 3 == 0 {
result.push(',');
}
result.push(c);
}
result.chars().rev().collect()
}

// ============================================================================
// UsageMetric Extension
// ============================================================================

impl UsageMetric {
/// Get human-readable display name for the metric
pub fn display_name(&self) -> &'static str {
match self {
Self::Messages => "Messages",
Self::StorageBytes => "Storage",
Self::ApiCalls => "API Calls",
Self::Bots => "Bots",
Self::Users => "Users",
Self::KbDocuments => "KB Documents",
Self::Apps => "Apps",
}
}
}

// ============================================================================
// Alert Service Factory
// ============================================================================

/// Create a fully configured alert manager with all handlers
pub fn create_alert_manager(
thresholds: Option<AlertThresholds>,
cooldown_seconds: Option<u64>,
) -> AlertManager {
let mut manager = AlertManager::new();

if let Some(t) = thresholds {
manager = manager.with_thresholds(t);
}

if let Some(c) = cooldown_seconds {
manager = manager.with_cooldown(c);
}

manager

}

/// Create default notification handlers
pub async fn register_default_handlers(manager: &AlertManager) {
manager
.register_handler(Arc::new(InAppNotificationHandler::new()))
.await;
manager
.register_handler(Arc::new(WebhookNotificationHandler::new()))
.await;
}