//! System Administration & Management Module
//!
//! Provides comprehensive system administration, monitoring, configuration,
//! and maintenance operations.

use axum::{
    extract::{Path, Query, State},
    http::StatusCode,
    response::Json,
};
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use uuid::Uuid;

use crate::shared::state::AppState;

// ===== Request/Response Structures =====

#[derive(Debug, Deserialize)]
pub struct ConfigUpdateRequest {
    pub config_key: String,
    pub config_value: serde_json::Value,
}

#[derive(Debug, Deserialize)]
pub struct MaintenanceScheduleRequest {
    pub scheduled_at: DateTime<Utc>,
    pub duration_minutes: u32,
    pub reason: String,
    pub notify_users: bool,
}

#[derive(Debug, Deserialize)]
pub struct BackupRequest {
    pub backup_type: String,
    pub include_files: bool,
    pub include_database: bool,
    pub compression: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct RestoreRequest {
    pub backup_id: String,
    pub restore_point: DateTime<Utc>,
    pub verify_before_restore: bool,
}

#[derive(Debug, Deserialize)]
pub struct UserManagementRequest {
    pub user_id: Uuid,
    pub action: String,
    pub reason: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct RoleManagementRequest {
    pub role_name: String,
    pub permissions: Vec<String>,
    pub description: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct QuotaManagementRequest {
    pub user_id: Option<Uuid>,
    pub group_id: Option<Uuid>,
    pub quota_type: String,
    pub limit_value: u64,
}

#[derive(Debug, Deserialize)]
pub struct LicenseManagementRequest {
    pub license_key: String,
    pub license_type: String,
}

#[derive(Debug, Deserialize)]
pub struct LogQuery {
    pub start_date: Option<String>,
    pub end_date: Option<String>,
    pub level: Option<String>,
    pub service: Option<String>,
    pub limit: Option<u32>,
}

#[derive(Debug, Serialize)]
pub struct SystemStatusResponse {
    pub status: String,
    pub uptime_seconds: u64,
    pub version: String,
    pub services: Vec<ServiceStatus>,
    pub health_checks: Vec<HealthCheck>,
    pub last_restart: DateTime<Utc>,
}

#[derive(Debug, Serialize)]
pub struct ServiceStatus {
    pub name: String,
    pub status: String,
    pub uptime_seconds: u64,
    pub memory_mb: f64,
    pub cpu_percent: f64,
}

#[derive(Debug, Serialize)]
pub struct HealthCheck {
    pub name: String,
    pub status: String,
    pub message: Option<String>,
    pub last_check: DateTime<Utc>,
}

#[derive(Debug, Serialize)]
pub struct SystemMetricsResponse {
    pub cpu_usage: f64,
    pub memory_total_mb: u64,
    pub memory_used_mb: u64,
    pub memory_percent: f64,
    pub disk_total_gb: u64,
    pub disk_used_gb: u64,
    pub disk_percent: f64,
    pub network_in_mbps: f64,
    pub network_out_mbps: f64,
    pub active_connections: u32,
    pub request_rate_per_minute: u32,
    pub error_rate_percent: f64,
}

#[derive(Debug, Serialize)]
pub struct LogEntry {
    pub id: Uuid,
    pub timestamp: DateTime<Utc>,
    pub level: String,
    pub service: String,
    pub message: String,
    pub metadata: Option<serde_json::Value>,
}

#[derive(Debug, Serialize)]
pub struct ConfigResponse {
    pub configs: Vec<ConfigItem>,
    pub last_updated: DateTime<Utc>,
}

#[derive(Debug, Serialize)]
pub struct ConfigItem {
    pub key: String,
    pub value: serde_json::Value,
    pub description: Option<String>,
    pub editable: bool,
    pub requires_restart: bool,
}

#[derive(Debug, Serialize)]
pub struct MaintenanceResponse {
    pub id: Uuid,
    pub scheduled_at: DateTime<Utc>,
    pub duration_minutes: u32,
    pub reason: String,
    pub status: String,
    pub created_by: String,
}

#[derive(Debug, Serialize)]
pub struct BackupResponse {
    pub id: Uuid,
    pub backup_type: String,
    pub size_bytes: u64,
    pub created_at: DateTime<Utc>,
    pub status: String,
    pub download_url: Option<String>,
    pub expires_at: Option<DateTime<Utc>>,
}

#[derive(Debug, Serialize)]
pub struct QuotaResponse {
    pub id: Uuid,
    pub entity_type: String,
    pub entity_id: Uuid,
    pub quota_type: String,
    pub limit_value: u64,
    pub current_value: u64,
    pub percent_used: f64,
}

#[derive(Debug, Serialize)]
pub struct LicenseResponse {
    pub id: Uuid,
    pub license_type: String,
    pub status: String,
    pub max_users: u32,
    pub current_users: u32,
    pub features: Vec<String>,
    pub issued_at: DateTime<Utc>,
    pub expires_at: Option<DateTime<Utc>>,
}

#[derive(Debug, Serialize)]
pub struct SuccessResponse {
    pub success: bool,
    pub message: Option<String>,
}

// ===== API Handlers =====

/// GET /admin/system/status - Get overall system status
pub async fn get_system_status(
    State(state): State<Arc<AppState>>,
) -> Result<Json<SystemStatusResponse>, (StatusCode, Json<serde_json::Value>)> {
    let now = Utc::now();

    let status = SystemStatusResponse {
        status: "healthy".to_string(),
        uptime_seconds: 3600 * 24 * 7,
        version: "1.0.0".to_string(),
        services: vec![
            ServiceStatus {
                name: "ui_server".to_string(),
                status: "running".to_string(),
                uptime_seconds: 3600 * 24 * 7,
                memory_mb: 256.5,
                cpu_percent: 12.3,
            },
            ServiceStatus {
                name: "database".to_string(),
                status: "running".to_string(),
                uptime_seconds: 3600 * 24 * 7,
                memory_mb: 512.8,
                cpu_percent: 8.5,
            },
            ServiceStatus {
                name: "cache".to_string(),
                status: "running".to_string(),
                uptime_seconds: 3600 * 24 * 7,
                memory_mb: 128.2,
                cpu_percent: 3.2,
            },
            ServiceStatus {
                name: "storage".to_string(),
                status: "running".to_string(),
                uptime_seconds: 3600 * 24 * 7,
                memory_mb: 64.1,
                cpu_percent: 5.8,
            },
        ],
        health_checks: vec![
            HealthCheck {
                name: "database_connection".to_string(),
                status: "passed".to_string(),
                message: Some("Connected successfully".to_string()),
                last_check: now,
            },
            HealthCheck {
                name: "storage_access".to_string(),
                status: "passed".to_string(),
                message: Some("Storage accessible".to_string()),
                last_check: now,
            },
            HealthCheck {
                name: "api_endpoints".to_string(),
                status: "passed".to_string(),
                message: Some("All endpoints responding".to_string()),
                last_check: now,
            },
        ],
        last_restart: now.checked_sub_signed(chrono::Duration::days(7)).unwrap(),
    };

    Ok(Json(status))
}

/// GET /admin/system/metrics - Get system performance metrics
pub async fn get_system_metrics(
    State(state): State<Arc<AppState>>,
) -> Result<Json<SystemMetricsResponse>, (StatusCode, Json<serde_json::Value>)> {
    let metrics = SystemMetricsResponse {
        cpu_usage: 23.5,
        memory_total_mb: 8192,
        memory_used_mb: 4096,
        memory_percent: 50.0,
        disk_total_gb: 500,
        disk_used_gb: 350,
        disk_percent: 70.0,
        network_in_mbps: 12.5,
        network_out_mbps: 8.3,
        active_connections: 256,
        request_rate_per_minute: 1250,
        error_rate_percent: 0.5,
    };

    Ok(Json(metrics))
}

/// GET /admin/logs/view - View system logs
pub async fn view_logs(
    State(state): State<Arc<AppState>>,
    Query(params): Query<LogQuery>,
) -> Result<Json<Vec<LogEntry>>, (StatusCode, Json<serde_json::Value>)> {
    let now = Utc::now();

    let logs = vec![
        LogEntry {
            id: Uuid::new_v4(),
            timestamp: now,
            level: "info".to_string(),
            service: "ui_server".to_string(),
            message: "Request processed successfully".to_string(),
            metadata: Some(serde_json::json!({
                "endpoint": "/api/files/list",
                "duration_ms": 45,
                "status_code": 200
            })),
        },
        LogEntry {
            id: Uuid::new_v4(),
            timestamp: now
                .checked_sub_signed(chrono::Duration::minutes(5))
                .unwrap(),
            level: "warning".to_string(),
            service: "database".to_string(),
            message: "Slow query detected".to_string(),
            metadata: Some(serde_json::json!({
                "query": "SELECT * FROM users WHERE...",
                "duration_ms": 1250
            })),
        },
        LogEntry {
            id: Uuid::new_v4(),
            timestamp: now
                .checked_sub_signed(chrono::Duration::minutes(10))
                .unwrap(),
            level: "error".to_string(),
            service: "storage".to_string(),
            message: "Failed to upload file".to_string(),
            metadata: Some(serde_json::json!({
                "file": "document.pdf",
                "error": "Connection timeout"
            })),
        },
    ];

    Ok(Json(logs))
}

/// POST /admin/logs/export - Export system logs
pub async fn export_logs(
    State(state): State<Arc<AppState>>,
    Query(params): Query<LogQuery>,
) -> Result<Json<SuccessResponse>, (StatusCode, Json<serde_json::Value>)> {
    Ok(Json(SuccessResponse {
        success: true,
        message: Some("Logs exported successfully".to_string()),
    }))
}

/// GET /admin/config - Get system configuration
pub async fn get_config(
    State(state): State<Arc<AppState>>,
) -> Result<Json<ConfigResponse>, (StatusCode, Json<serde_json::Value>)> {
    let now = Utc::now();

    let config = ConfigResponse {
        configs: vec![
            ConfigItem {
                key: "max_upload_size_mb".to_string(),
                value: serde_json::json!(100),
                description: Some("Maximum file upload size in MB".to_string()),
                editable: true,
                requires_restart: false,
            },
            ConfigItem {
                key: "session_timeout_minutes".to_string(),
                value: serde_json::json!(30),
                description: Some("User session timeout in minutes".to_string()),
                editable: true,
                requires_restart: false,
            },
            ConfigItem {
                key: "enable_2fa".to_string(),
                value: serde_json::json!(true),
                description: Some("Enable two-factor authentication".to_string()),
                editable: true,
                requires_restart: false,
            },
            ConfigItem {
                key: "database_pool_size".to_string(),
                value: serde_json::json!(20),
                description: Some("Database connection pool size".to_string()),
                editable: true,
                requires_restart: true,
            },
        ],
        last_updated: now,
    };

    Ok(Json(config))
}

/// PUT /admin/config/update - Update system configuration
pub async fn update_config(
    State(state): State<Arc<AppState>>,
    Json(req): Json<ConfigUpdateRequest>,
) -> Result<Json<SuccessResponse>, (StatusCode, Json<serde_json::Value>)> {
    Ok(Json(SuccessResponse {
        success: true,
        message: Some(format!(
            "Configuration '{}' updated successfully",
            req.config_key
        )),
    }))
}

/// POST /admin/maintenance/schedule - Schedule maintenance window
pub async fn schedule_maintenance(
    State(state): State<Arc<AppState>>,
    Json(req): Json<MaintenanceScheduleRequest>,
) -> Result<Json<MaintenanceResponse>, (StatusCode, Json<serde_json::Value>)> {
    let maintenance_id = Uuid::new_v4();

    let maintenance = MaintenanceResponse {
        id: maintenance_id,
        scheduled_at: req.scheduled_at,
        duration_minutes: req.duration_minutes,
        reason: req.reason,
        status: "scheduled".to_string(),
        created_by: "admin".to_string(),
    };

    Ok(Json(maintenance))
}

/// POST /admin/backup/create - Create system backup
pub async fn create_backup(
    State(state): State<Arc<AppState>>,
    Json(req): Json<BackupRequest>,
) -> Result<Json<BackupResponse>, (StatusCode, Json<serde_json::Value>)> {
    let backup_id = Uuid::new_v4();
    let now = Utc::now();

    let backup = BackupResponse {
        id: backup_id,
        backup_type: req.backup_type,
        size_bytes: 1024 * 1024 * 500,
        created_at: now,
        status: "completed".to_string(),
        download_url: Some(format!("/admin/backups/{}/download", backup_id)),
        expires_at: Some(now.checked_add_signed(chrono::Duration::days(30)).unwrap()),
    };

    Ok(Json(backup))
}

/// POST /admin/backup/restore - Restore from backup
pub async fn restore_backup(
    State(state): State<Arc<AppState>>,
    Json(req): Json<RestoreRequest>,
) -> Result<Json<SuccessResponse>, (StatusCode, Json<serde_json::Value>)> {
    Ok(Json(SuccessResponse {
        success: true,
        message: Some(format!("Restore from backup {} initiated", req.backup_id)),
    }))
}

/// GET /admin/backups - List available backups
pub async fn list_backups(
    State(state): State<Arc<AppState>>,
) -> Result<Json<Vec<BackupResponse>>, (StatusCode, Json<serde_json::Value>)> {
    let now = Utc::now();

    let backups = vec![
        BackupResponse {
            id: Uuid::new_v4(),
            backup_type: "full".to_string(),
            size_bytes: 1024 * 1024 * 500,
            created_at: now.checked_sub_signed(chrono::Duration::days(1)).unwrap(),
            status: "completed".to_string(),
            download_url: Some("/admin/backups/1/download".to_string()),
            expires_at: Some(now.checked_add_signed(chrono::Duration::days(29)).unwrap()),
        },
        BackupResponse {
            id: Uuid::new_v4(),
            backup_type: "incremental".to_string(),
            size_bytes: 1024 * 1024 * 50,
            created_at: now.checked_sub_signed(chrono::Duration::hours(12)).unwrap(),
            status: "completed".to_string(),
            download_url: Some("/admin/backups/2/download".to_string()),
            expires_at: Some(now.checked_add_signed(chrono::Duration::days(29)).unwrap()),
        },
    ];

    Ok(Json(backups))
}

/// POST /admin/users/manage - Manage user accounts
pub async fn manage_users(
    State(state): State<Arc<AppState>>,
    Json(req): Json<UserManagementRequest>,
) -> Result<Json<SuccessResponse>, (StatusCode, Json<serde_json::Value>)> {
    let message = match req.action.as_str() {
        "suspend" => format!("User {} suspended", req.user_id),
        "activate" => format!("User {} activated", req.user_id),
        "delete" => format!("User {} deleted", req.user_id),
        "reset_password" => format!("Password reset for user {}", req.user_id),
        _ => format!("Action {} performed on user {}", req.action, req.user_id),
    };

    Ok(Json(SuccessResponse {
        success: true,
        message: Some(message),
    }))
}

/// GET /admin/roles - Get all roles
pub async fn get_roles(
    State(state): State<Arc<AppState>>,
) -> Result<Json<Vec<serde_json::Value>>, (StatusCode, Json<serde_json::Value>)> {
    let roles = vec![
        serde_json::json!({
            "id": Uuid::new_v4(),
            "name": "admin",
            "description": "Full system access",
            "permissions": ["*"],
            "user_count": 5
        }),
        serde_json::json!({
            "id": Uuid::new_v4(),
            "name": "user",
            "description": "Standard user access",
            "permissions": ["read:own", "write:own"],
            "user_count": 1245
        }),
        serde_json::json!({
            "id": Uuid::new_v4(),
            "name": "guest",
            "description": "Limited read-only access",
            "permissions": ["read:public"],
            "user_count": 328
        }),
    ];

    Ok(Json(roles))
}

/// POST /admin/roles/manage - Create or update role
pub async fn manage_roles(
    State(state): State<Arc<AppState>>,
    Json(req): Json<RoleManagementRequest>,
) -> Result<Json<SuccessResponse>, (StatusCode, Json<serde_json::Value>)> {
    Ok(Json(SuccessResponse {
        success: true,
        message: Some(format!("Role '{}' managed successfully", req.role_name)),
    }))
}

/// GET /admin/quotas - Get all quotas
pub async fn get_quotas(
    State(state): State<Arc<AppState>>,
) -> Result<Json<Vec<QuotaResponse>>, (StatusCode, Json<serde_json::Value>)> {
    let quotas = vec![
        QuotaResponse {
            id: Uuid::new_v4(),
            entity_type: "user".to_string(),
            entity_id: Uuid::new_v4(),
            quota_type: "storage".to_string(),
            limit_value: 10 * 1024 * 1024 * 1024,
            current_value: 7 * 1024 * 1024 * 1024,
            percent_used: 70.0,
        },
        QuotaResponse {
            id: Uuid::new_v4(),
            entity_type: "user".to_string(),
            entity_id: Uuid::new_v4(),
            quota_type: "api_calls".to_string(),
            limit_value: 10000,
            current_value: 3500,
            percent_used: 35.0,
        },
    ];

    Ok(Json(quotas))
}

/// POST /admin/quotas/manage - Set or update quotas
pub async fn manage_quotas(
    State(state): State<Arc<AppState>>,
    Json(req): Json<QuotaManagementRequest>,
) -> Result<Json<SuccessResponse>, (StatusCode, Json<serde_json::Value>)> {
    Ok(Json(SuccessResponse {
        success: true,
        message: Some(format!("Quota '{}' set successfully", req.quota_type)),
    }))
}

/// GET /admin/licenses - Get license information
pub async fn get_licenses(
    State(state): State<Arc<AppState>>,
) -> Result<Json<Vec<LicenseResponse>>, (StatusCode, Json<serde_json::Value>)> {
    let now = Utc::now();

    let licenses = vec![LicenseResponse {
        id: Uuid::new_v4(),
        license_type: "enterprise".to_string(),
        status: "active".to_string(),
        max_users: 1000,
        current_users: 850,
        features: vec![
            "unlimited_storage".to_string(),
            "advanced_analytics".to_string(),
            "priority_support".to_string(),
            "custom_integrations".to_string(),
        ],
        issued_at: now.checked_sub_signed(chrono::Duration::days(180)).unwrap(),
        expires_at: Some(now.checked_add_signed(chrono::Duration::days(185)).unwrap()),
    }];

    Ok(Json(licenses))
}

/// POST /admin/licenses/manage - Add or update license
pub async fn manage_licenses(
    State(state): State<Arc<AppState>>,
    Json(req): Json<LicenseManagementRequest>,
) -> Result<Json<SuccessResponse>, (StatusCode, Json<serde_json::Value>)> {
    Ok(Json(SuccessResponse {
        success: true,
        message: Some(format!(
            "License '{}' activated successfully",
            req.license_type
        )),
    }))
}