use actix_web::{HttpResponse, Result, web};
use serde::{Deserialize, Serialize};
use std::time::{Duration, Instant};

#[derive(Debug, Serialize, Deserialize)]
pub struct HealthStatus {
    pub status: String,
    pub timestamp: String,
    pub version: String,
    pub uptime_seconds: u64,
    pub checks: Vec<HealthCheck>,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct HealthCheck {
    pub name: String,
    pub status: String,
    pub response_time_ms: u64,
    pub message: Option<String>,
    pub details: Option<serde_json::Value>,
}

impl HealthStatus {
    pub fn new() -> Self {
        Self {
            status: "unknown".to_string(),
            timestamp: chrono::Utc::now().to_rfc3339(),
            version: env!("CARGO_PKG_VERSION").to_string(),
            uptime_seconds: 0,
            checks: Vec::new(),
        }
    }

    pub fn set_uptime(&mut self, uptime: Duration) {
        self.uptime_seconds = uptime.as_secs();
    }

    pub fn add_check(&mut self, check: HealthCheck) {
        self.checks.push(check);
    }

    pub fn calculate_overall_status(&mut self) {
        let all_healthy = self.checks.iter().all(|check| check.status == "healthy");
        let any_degraded = self.checks.iter().any(|check| check.status == "degraded");

        self.status = if all_healthy {
            "healthy".to_string()
        } else if any_degraded {
            "degraded".to_string()
        } else {
            "unhealthy".to_string()
        };
    }
}

impl HealthCheck {
    pub fn new(name: &str) -> Self {
        Self {
            name: name.to_string(),
            status: "unknown".to_string(),
            response_time_ms: 0,
            message: None,
            details: None,
        }
    }

    pub fn healthy(name: &str, response_time_ms: u64) -> Self {
        Self {
            name: name.to_string(),
            status: "healthy".to_string(),
            response_time_ms,
            message: Some("OK".to_string()),
            details: None,
        }
    }

    pub fn degraded(name: &str, response_time_ms: u64, message: &str) -> Self {
        Self {
            name: name.to_string(),
            status: "degraded".to_string(),
            response_time_ms,
            message: Some(message.to_string()),
            details: None,
        }
    }

    pub fn unhealthy(name: &str, response_time_ms: u64, error: &str) -> Self {
        Self {
            name: name.to_string(),
            status: "unhealthy".to_string(),
            response_time_ms,
            message: Some(error.to_string()),
            details: None,
        }
    }

    pub fn with_details(mut self, details: serde_json::Value) -> Self {
        self.details = Some(details);
        self
    }
}

/// Health check endpoint
pub async fn health_check() -> Result<HttpResponse> {
    let start_time = Instant::now();
    let mut status = HealthStatus::new();

    // Set uptime (in a real app, you'd track this from startup)
    status.set_uptime(Duration::from_secs(3600)); // Placeholder

    // Check database connectivity
    let db_check = check_database_health().await;
    status.add_check(db_check);

    // Check Redis connectivity
    let redis_check = check_redis_health().await;
    status.add_check(redis_check);

    // Check Stripe connectivity
    let stripe_check = check_stripe_health().await;
    status.add_check(stripe_check);

    // Check file system
    let fs_check = check_filesystem_health().await;
    status.add_check(fs_check);

    // Check memory usage
    let memory_check = check_memory_health().await;
    status.add_check(memory_check);

    // Calculate overall status
    status.calculate_overall_status();

    let response_code = match status.status.as_str() {
        "healthy" => 200,
        "degraded" => 200, // Still operational
        _ => 503,          // Service unavailable
    };

    log::info!(
        "Health check completed in {}ms - Status: {}",
        start_time.elapsed().as_millis(),
        status.status
    );

    Ok(
        HttpResponse::build(actix_web::http::StatusCode::from_u16(response_code).unwrap())
            .json(status),
    )
}

/// Detailed health check endpoint for monitoring systems
pub async fn health_check_detailed() -> Result<HttpResponse> {
    let start_time = Instant::now();
    let mut status = HealthStatus::new();

    // Set uptime
    status.set_uptime(Duration::from_secs(3600)); // Placeholder

    // Detailed database check
    let db_check = check_database_health_detailed().await;
    status.add_check(db_check);

    // Detailed Redis check
    let redis_check = check_redis_health_detailed().await;
    status.add_check(redis_check);

    // Detailed Stripe check
    let stripe_check = check_stripe_health_detailed().await;
    status.add_check(stripe_check);

    // Check external dependencies
    let external_check = check_external_dependencies().await;
    status.add_check(external_check);

    // Performance metrics
    let perf_check = check_performance_metrics().await;
    status.add_check(perf_check);

    status.calculate_overall_status();

    log::info!(
        "Detailed health check completed in {}ms - Status: {}",
        start_time.elapsed().as_millis(),
        status.status
    );

    Ok(HttpResponse::Ok().json(status))
}

/// Simple readiness check for load balancers
pub async fn readiness_check() -> Result<HttpResponse> {
    // Quick checks for essential services
    let db_ok = check_database_connectivity().await;
    let redis_ok = check_redis_connectivity().await;

    if db_ok && redis_ok {
        Ok(HttpResponse::Ok().json(serde_json::json!({
            "status": "ready",
            "timestamp": chrono::Utc::now().to_rfc3339()
        })))
    } else {
        Ok(HttpResponse::ServiceUnavailable().json(serde_json::json!({
            "status": "not_ready",
            "timestamp": chrono::Utc::now().to_rfc3339()
        })))
    }
}

/// Simple liveness check
pub async fn liveness_check() -> Result<HttpResponse> {
    Ok(HttpResponse::Ok().json(serde_json::json!({
        "status": "alive",
        "timestamp": chrono::Utc::now().to_rfc3339(),
        "version": env!("CARGO_PKG_VERSION")
    })))
}

// Health check implementations

async fn check_database_health() -> HealthCheck {
    let start = Instant::now();

    match crate::db::db::get_db() {
        Ok(_) => HealthCheck::healthy("database", start.elapsed().as_millis() as u64),
        Err(e) => HealthCheck::unhealthy(
            "database",
            start.elapsed().as_millis() as u64,
            &format!("Database connection failed: {}", e),
        ),
    }
}

async fn check_database_health_detailed() -> HealthCheck {
    let start = Instant::now();

    match crate::db::db::get_db() {
        Ok(db) => {
            // Try to perform a simple operation
            let details = serde_json::json!({
                "connection_pool_size": "N/A", // Would need to expose from heromodels
                "active_connections": "N/A",
                "database_size": "N/A"
            });

            HealthCheck::healthy("database", start.elapsed().as_millis() as u64)
                .with_details(details)
        }
        Err(e) => HealthCheck::unhealthy(
            "database",
            start.elapsed().as_millis() as u64,
            &format!("Database connection failed: {}", e),
        ),
    }
}

async fn check_redis_health() -> HealthCheck {
    let start = Instant::now();

    // Try to connect to Redis
    match crate::utils::redis_service::get_connection() {
        Ok(_) => HealthCheck::healthy("redis", start.elapsed().as_millis() as u64),
        Err(e) => HealthCheck::unhealthy(
            "redis",
            start.elapsed().as_millis() as u64,
            &format!("Redis connection failed: {}", e),
        ),
    }
}

async fn check_redis_health_detailed() -> HealthCheck {
    let start = Instant::now();

    match crate::utils::redis_service::get_connection() {
        Ok(_) => {
            let details = serde_json::json!({
                "connection_status": "connected",
                "memory_usage": "N/A",
                "connected_clients": "N/A"
            });

            HealthCheck::healthy("redis", start.elapsed().as_millis() as u64).with_details(details)
        }
        Err(e) => HealthCheck::unhealthy(
            "redis",
            start.elapsed().as_millis() as u64,
            &format!("Redis connection failed: {}", e),
        ),
    }
}

async fn check_stripe_health() -> HealthCheck {
    let start = Instant::now();

    // Check if Stripe configuration is available
    let config = crate::config::get_config();
    if !config.stripe.secret_key.is_empty() {
        HealthCheck::healthy("stripe", start.elapsed().as_millis() as u64)
    } else {
        HealthCheck::degraded(
            "stripe",
            start.elapsed().as_millis() as u64,
            "Stripe secret key not configured",
        )
    }
}

async fn check_stripe_health_detailed() -> HealthCheck {
    let start = Instant::now();

    let config = crate::config::get_config();
    let has_secret = !config.stripe.secret_key.is_empty();
    let has_webhook_secret = config.stripe.webhook_secret.is_some();

    let details = serde_json::json!({
        "secret_key_configured": has_secret,
        "webhook_secret_configured": has_webhook_secret,
        "api_version": "2023-10-16" // Current Stripe API version
    });

    if has_secret && has_webhook_secret {
        HealthCheck::healthy("stripe", start.elapsed().as_millis() as u64).with_details(details)
    } else {
        HealthCheck::degraded(
            "stripe",
            start.elapsed().as_millis() as u64,
            "Stripe configuration incomplete",
        )
        .with_details(details)
    }
}

async fn check_filesystem_health() -> HealthCheck {
    let start = Instant::now();

    // Check if we can write to the data directory
    match std::fs::create_dir_all("data") {
        Ok(_) => {
            // Try to write a test file
            match std::fs::write("data/.health_check", "test") {
                Ok(_) => {
                    // Clean up
                    let _ = std::fs::remove_file("data/.health_check");
                    HealthCheck::healthy("filesystem", start.elapsed().as_millis() as u64)
                }
                Err(e) => HealthCheck::unhealthy(
                    "filesystem",
                    start.elapsed().as_millis() as u64,
                    &format!("Cannot write to data directory: {}", e),
                ),
            }
        }
        Err(e) => HealthCheck::unhealthy(
            "filesystem",
            start.elapsed().as_millis() as u64,
            &format!("Cannot create data directory: {}", e),
        ),
    }
}

async fn check_memory_health() -> HealthCheck {
    let start = Instant::now();

    // Basic memory check (in a real app, you'd use system metrics)
    let details = serde_json::json!({
        "status": "basic_check_only",
        "note": "Detailed memory metrics require system integration"
    });

    HealthCheck::healthy("memory", start.elapsed().as_millis() as u64).with_details(details)
}

async fn check_external_dependencies() -> HealthCheck {
    let start = Instant::now();

    // Check external services (placeholder)
    let details = serde_json::json!({
        "external_apis": "not_implemented",
        "third_party_services": "not_implemented"
    });

    HealthCheck::healthy("external_dependencies", start.elapsed().as_millis() as u64)
        .with_details(details)
}

async fn check_performance_metrics() -> HealthCheck {
    let start = Instant::now();

    let details = serde_json::json!({
        "avg_response_time_ms": "N/A",
        "requests_per_second": "N/A",
        "error_rate": "N/A",
        "cpu_usage": "N/A"
    });

    HealthCheck::healthy("performance", start.elapsed().as_millis() as u64).with_details(details)
}

// Quick connectivity checks for readiness

async fn check_database_connectivity() -> bool {
    crate::db::db::get_db().is_ok()
}

async fn check_redis_connectivity() -> bool {
    crate::utils::redis_service::get_connection().is_ok()
}

/// Configure health check routes
pub fn configure_health_routes(cfg: &mut web::ServiceConfig) {
    cfg.service(
        web::scope("/health")
            .route("", web::get().to(health_check))
            .route("/detailed", web::get().to(health_check_detailed))
            .route("/ready", web::get().to(readiness_check))
            .route("/live", web::get().to(liveness_check)),
    );
}