//! Audit Logging Module
//!
//! Comprehensive audit trail system for all KMS operations with
//! multiple backends and configurable retention policies.

use std::collections::HashMap;

use async_trait::async_trait;
use chrono::Utc;

use crate::kms::config::{AuditBackend, AuditConfig};
use crate::kms::error::KmsError;
use crate::kms::traits::AuditLog;
use crate::kms::types::{AuditEvent, AuditEventType, HealthStatus};

/// Audit logger with multiple backend support
pub struct AuditLogger {
    backend: Box<dyn AuditLog>,
    /// Configuration for audit backend and policies
    #[allow(dead_code)]
    config: AuditConfig,
}

impl AuditLogger {
    /// Create a new audit logger
    pub async fn new(config: AuditConfig) -> Result<Self, KmsError> {
        let backend = Self::create_backend(&config).await?;

        Ok(Self { backend, config })
    }

    /// Create audit backend based on configuration
    async fn create_backend(config: &AuditConfig) -> Result<Box<dyn AuditLog>, KmsError> {
        match config.backend {
            AuditBackend::File => Ok(Box::new(FileAuditBackend::new(config.clone()).await?)),
            AuditBackend::Database => {
                Ok(Box::new(DatabaseAuditBackend::new(config.clone()).await?))
            }
            AuditBackend::Syslog => Ok(Box::new(SyslogAuditBackend::new(config.clone()).await?)),
            AuditBackend::Stdout => Ok(Box::new(StdoutAuditBackend::new(config.clone()).await?)),
        }
    }

    /// Log an audit event
    pub async fn log_event(&self, event: AuditEvent) -> Result<(), KmsError> {
        self.backend.log_event(event).await
    }
}

/// File-based audit backend (planned feature)
#[allow(dead_code)]
struct FileAuditBackend {
    config: AuditConfig,
}

impl FileAuditBackend {
    async fn new(config: AuditConfig) -> Result<Self, KmsError> {
        Ok(Self { config })
    }
}

#[async_trait]
impl AuditLog for FileAuditBackend {
    async fn log_event(&self, _event: AuditEvent) -> Result<(), KmsError> {
        // TODO: Implement file-based audit logging
        Ok(())
    }

    async fn query_events(
        &self,
        _filters: Option<HashMap<String, String>>,
        _limit: Option<usize>,
        _offset: Option<usize>,
    ) -> Result<Vec<AuditEvent>, KmsError> {
        // TODO: Implement event querying
        Ok(Vec::new())
    }

    async fn get_stats(&self) -> Result<HashMap<String, i64>, KmsError> {
        // TODO: Implement audit statistics
        Ok(HashMap::new())
    }

    async fn archive_events(&self, _older_than_days: u32) -> Result<u64, KmsError> {
        // TODO: Implement event archiving
        Ok(0)
    }

    async fn health_check(&self) -> Result<HealthStatus, KmsError> {
        Ok(HealthStatus::healthy("File audit backend operational"))
    }
}

/// Database-based audit backend (planned feature)
#[allow(dead_code)]
struct DatabaseAuditBackend {
    config: AuditConfig,
}

impl DatabaseAuditBackend {
    async fn new(config: AuditConfig) -> Result<Self, KmsError> {
        Ok(Self { config })
    }
}

#[async_trait]
impl AuditLog for DatabaseAuditBackend {
    async fn log_event(&self, _event: AuditEvent) -> Result<(), KmsError> {
        // TODO: Implement database audit logging
        Ok(())
    }

    async fn query_events(
        &self,
        _filters: Option<HashMap<String, String>>,
        _limit: Option<usize>,
        _offset: Option<usize>,
    ) -> Result<Vec<AuditEvent>, KmsError> {
        // TODO: Implement event querying
        Ok(Vec::new())
    }

    async fn get_stats(&self) -> Result<HashMap<String, i64>, KmsError> {
        // TODO: Implement audit statistics
        Ok(HashMap::new())
    }

    async fn archive_events(&self, _older_than_days: u32) -> Result<u64, KmsError> {
        // TODO: Implement event archiving
        Ok(0)
    }

    async fn health_check(&self) -> Result<HealthStatus, KmsError> {
        Ok(HealthStatus::healthy("Database audit backend operational"))
    }
}

/// Syslog audit backend (planned feature)
#[allow(dead_code)]
struct SyslogAuditBackend {
    config: AuditConfig,
}

impl SyslogAuditBackend {
    async fn new(config: AuditConfig) -> Result<Self, KmsError> {
        Ok(Self { config })
    }
}

#[async_trait]
impl AuditLog for SyslogAuditBackend {
    async fn log_event(&self, _event: AuditEvent) -> Result<(), KmsError> {
        // TODO: Implement syslog audit logging
        Ok(())
    }

    async fn query_events(
        &self,
        _filters: Option<HashMap<String, String>>,
        _limit: Option<usize>,
        _offset: Option<usize>,
    ) -> Result<Vec<AuditEvent>, KmsError> {
        // TODO: Implement event querying
        Ok(Vec::new())
    }

    async fn get_stats(&self) -> Result<HashMap<String, i64>, KmsError> {
        // TODO: Implement audit statistics
        Ok(HashMap::new())
    }

    async fn archive_events(&self, _older_than_days: u32) -> Result<u64, KmsError> {
        // TODO: Implement event archiving
        Ok(0)
    }

    async fn health_check(&self) -> Result<HealthStatus, KmsError> {
        Ok(HealthStatus::healthy("Syslog audit backend operational"))
    }
}

/// Stdout audit backend for development (planned feature)
#[allow(dead_code)]
struct StdoutAuditBackend {
    config: AuditConfig,
}

impl StdoutAuditBackend {
    async fn new(config: AuditConfig) -> Result<Self, KmsError> {
        Ok(Self { config })
    }
}

#[async_trait]
impl AuditLog for StdoutAuditBackend {
    async fn log_event(&self, event: AuditEvent) -> Result<(), KmsError> {
        println!(
            "[AUDIT] {}",
            serde_json::to_string(&event).unwrap_or_default()
        );
        Ok(())
    }

    async fn query_events(
        &self,
        _filters: Option<HashMap<String, String>>,
        _limit: Option<usize>,
        _offset: Option<usize>,
    ) -> Result<Vec<AuditEvent>, KmsError> {
        // Cannot query stdout events
        Ok(Vec::new())
    }

    async fn get_stats(&self) -> Result<HashMap<String, i64>, KmsError> {
        Ok(HashMap::new())
    }

    async fn archive_events(&self, _older_than_days: u32) -> Result<u64, KmsError> {
        // Cannot archive stdout events
        Ok(0)
    }

    async fn health_check(&self) -> Result<HealthStatus, KmsError> {
        Ok(HealthStatus::healthy("Stdout audit backend operational"))
    }
}

// Vault Secrets Audit Helpers
impl AuditLogger {
    /// Log vault secret created
    pub async fn log_secret_created(
        &self,
        secret_id: &str,
        path: &str,
        user_id: &str,
    ) -> Result<(), KmsError> {
        let event = AuditEvent {
            event_id: uuid::Uuid::new_v4(),
            timestamp: Utc::now(),
            event_type: AuditEventType::KeyAccessed,
            user_id: Some(user_id.to_string()),
            resource_id: Some(secret_id.to_string()),
            action: "create".to_string(),
            result: "success".to_string(),
            details: serde_json::json!({
                "secret_id": secret_id,
                "path": path,
            }),
            ip_address: None,
            user_agent: None,
            success: true,
            message: format!("Vault secret {} created at path {}", secret_id, path),
            metadata: std::collections::HashMap::new(),
            source_ip: None,
        };

        self.log_event(event).await
    }

    /// Log vault secret accessed
    pub async fn log_secret_accessed(
        &self,
        secret_id: &str,
        path: &str,
        user_id: &str,
    ) -> Result<(), KmsError> {
        let event = AuditEvent {
            event_id: uuid::Uuid::new_v4(),
            timestamp: Utc::now(),
            event_type: AuditEventType::KeyAccessed,
            user_id: Some(user_id.to_string()),
            resource_id: Some(secret_id.to_string()),
            action: "read".to_string(),
            result: "success".to_string(),
            details: serde_json::json!({
                "secret_id": secret_id,
                "path": path,
            }),
            ip_address: None,
            user_agent: None,
            success: true,
            message: format!("Vault secret {} accessed at path {}", secret_id, path),
            metadata: std::collections::HashMap::new(),
            source_ip: None,
        };

        self.log_event(event).await
    }

    /// Log vault secret updated
    pub async fn log_secret_updated(
        &self,
        secret_id: &str,
        path: &str,
        new_version: i32,
        user_id: &str,
    ) -> Result<(), KmsError> {
        let event = AuditEvent {
            event_id: uuid::Uuid::new_v4(),
            timestamp: Utc::now(),
            event_type: AuditEventType::KeyAccessed,
            user_id: Some(user_id.to_string()),
            resource_id: Some(secret_id.to_string()),
            action: "update".to_string(),
            result: "success".to_string(),
            details: serde_json::json!({
                "secret_id": secret_id,
                "path": path,
                "new_version": new_version,
            }),
            ip_address: None,
            user_agent: None,
            success: true,
            message: format!(
                "Vault secret {} updated at path {} to version {}",
                secret_id, path, new_version
            ),
            metadata: std::collections::HashMap::new(),
            source_ip: None,
        };

        self.log_event(event).await
    }

    /// Log vault secret deleted
    pub async fn log_secret_deleted(
        &self,
        secret_id: &str,
        path: &str,
        user_id: &str,
    ) -> Result<(), KmsError> {
        let event = AuditEvent {
            event_id: uuid::Uuid::new_v4(),
            timestamp: Utc::now(),
            event_type: AuditEventType::KeyAccessed,
            user_id: Some(user_id.to_string()),
            resource_id: Some(secret_id.to_string()),
            action: "delete".to_string(),
            result: "success".to_string(),
            details: serde_json::json!({
                "secret_id": secret_id,
                "path": path,
            }),
            ip_address: None,
            user_agent: None,
            success: true,
            message: format!("Vault secret {} deleted at path {}", secret_id, path),
            metadata: std::collections::HashMap::new(),
            source_ip: None,
        };

        self.log_event(event).await
    }

    /// Log vault secret version restored
    pub async fn log_secret_restored(
        &self,
        secret_id: &str,
        path: &str,
        restored_version: i32,
        new_version: i32,
        user_id: &str,
    ) -> Result<(), KmsError> {
        let event = AuditEvent {
            event_id: uuid::Uuid::new_v4(),
            timestamp: Utc::now(),
            event_type: AuditEventType::KeyAccessed,
            user_id: Some(user_id.to_string()),
            resource_id: Some(secret_id.to_string()),
            action: "restore".to_string(),
            result: "success".to_string(),
            details: serde_json::json!({
                "secret_id": secret_id,
                "path": path,
                "restored_from_version": restored_version,
                "new_version": new_version,
            }),
            ip_address: None,
            user_agent: None,
            success: true,
            message: format!(
                "Vault secret {} restored at path {} from version {} to version {}",
                secret_id, path, restored_version, new_version
            ),
            metadata: std::collections::HashMap::new(),
            source_ip: None,
        };

        self.log_event(event).await
    }
}
