oxirs-fuseki 0.2.4

//! SAML 2.0 authentication support

#[cfg(feature = "saml")]
use async_trait::async_trait;
#[cfg(feature = "saml")]
use base64::{engine::general_purpose, Engine as _};
#[cfg(feature = "saml")]
use chrono::{DateTime, Utc};
#[cfg(feature = "saml")]
use serde::{Deserialize, Serialize};
#[cfg(feature = "saml")]
use std::{
    collections::HashMap,
    sync::Arc,
    time::{Duration, SystemTime, UNIX_EPOCH},
};
#[cfg(feature = "saml")]
use tokio::sync::RwLock;
#[cfg(feature = "saml")]
use url::Url;
#[cfg(feature = "saml")]
use uuid::Uuid;
// TODO: Uncomment when xmlsec crate is added and XML parsing is implemented
// #[cfg(feature = "saml")]
// use xmlsec::{XmlSecKey, XmlSecKeyFormat, XmlSecSignatureContext};

use crate::{
    auth::{AuthResult, User},
    error::{FusekiError, FusekiResult},
};

/// SAML 2.0 configuration
#[derive(Debug, Clone)]
pub struct SamlConfig {
    /// Service Provider (SP) configuration
    pub sp: ServiceProviderConfig,
    /// Identity Provider (IdP) configuration
    pub idp: IdentityProviderConfig,
    /// Attribute mapping configuration
    pub attribute_mapping: AttributeMapping,
    /// Session configuration
    pub session: SessionConfig,
}

/// Type alias for handler compatibility
pub type SamlSpConfig = ServiceProviderConfig;

/// Type alias for handler compatibility  
pub type SamlAttributeMappings = AttributeMapping;

/// Service Provider configuration
#[derive(Debug, Clone)]
pub struct ServiceProviderConfig {
    /// SP Entity ID
    pub entity_id: String,
    /// Assertion Consumer Service URL
    pub acs_url: Url,
    /// Single Logout Service URL
    pub sls_url: Option<Url>,
    /// SP Certificate for signing
    pub certificate: Option<String>,
    /// SP Private key for signing
    pub private_key: Option<String>,
}

/// Identity Provider configuration
#[derive(Debug, Clone)]
pub struct IdentityProviderConfig {
    /// IdP Entity ID
    pub entity_id: String,
    /// Single Sign-On Service URL
    pub sso_url: Url,
    /// Single Logout Service URL
    pub slo_url: Option<Url>,
    /// IdP Certificate for signature verification
    pub certificate: String,
    /// Metadata URL (optional)
    pub metadata_url: Option<Url>,
}

/// Attribute mapping from SAML assertions to user properties
#[derive(Debug, Clone)]
pub struct AttributeMapping {
    /// Username attribute name
    pub username: String,
    /// Email attribute name
    pub email: Option<String>,
    /// Display name attribute name
    pub display_name: Option<String>,
    /// Groups/roles attribute name
    pub groups: Option<String>,
    /// Additional custom attributes
    pub custom: HashMap<String, String>,
}

impl Default for AttributeMapping {
    fn default() -> Self {
        Self {
            username: "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name".to_string(),
            email: Some(
                "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress".to_string(),
            ),
            display_name: Some(
                "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/givenname".to_string(),
            ),
            groups: Some("http://schemas.xmlsoap.org/claims/Group".to_string()),
            custom: HashMap::new(),
        }
    }
}

/// SAML session configuration
#[derive(Debug, Clone)]
pub struct SessionConfig {
    /// Session timeout duration
    pub timeout: Duration,
    /// Allow IdP-initiated SSO
    pub allow_idp_initiated: bool,
    /// Force authentication
    pub force_authn: bool,
    /// Session index tracking
    pub track_session_index: bool,
}

impl Default for SessionConfig {
    fn default() -> Self {
        Self {
            timeout: Duration::from_secs(3600), // 1 hour
            allow_idp_initiated: false,
            force_authn: false,
            track_session_index: true,
        }
    }
}

/// SAML 2.0 authentication provider
pub struct SamlProvider {
    pub config: SamlConfig,
    sessions: Arc<RwLock<HashMap<String, SamlSession>>>,
    pending_requests: Arc<RwLock<HashMap<String, PendingRequest>>>,
}

/// Active SAML session
#[derive(Debug, Clone)]
struct SamlSession {
    /// User information
    user: User,
    /// Session index from IdP
    session_index: Option<String>,
    /// Session creation time
    created_at: SystemTime,
    /// Session expiry time
    expires_at: SystemTime,
    /// SAML attributes
    attributes: HashMap<String, Vec<String>>,
}

/// Pending authentication request
#[derive(Debug, Clone)]
struct PendingRequest {
    /// Request ID
    id: String,
    /// Relay state
    relay_state: Option<String>,
    /// Request timestamp
    timestamp: SystemTime,
}

/// SAML AuthN request
#[derive(Debug, Serialize)]
pub struct AuthnRequest {
    /// Request ID
    pub id: String,
    /// Issue instant
    pub issue_instant: DateTime<Utc>,
    /// Destination URL
    pub destination: Url,
    /// Issuer (SP entity ID)
    pub issuer: String,
    /// Assertion Consumer Service URL
    pub acs_url: Url,
    /// Protocol binding
    pub protocol_binding: String,
    /// Force authentication
    pub force_authn: bool,
}

impl AuthnRequest {
    /// Create a new authentication request
    pub fn new(config: &SamlConfig) -> Self {
        Self {
            id: format!("_{}", Uuid::new_v4()),
            issue_instant: Utc::now(),
            destination: config.idp.sso_url.clone(),
            issuer: config.sp.entity_id.clone(),
            acs_url: config.sp.acs_url.clone(),
            protocol_binding: "urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST".to_string(),
            force_authn: config.session.force_authn,
        }
    }

    /// Generate XML for the request
    pub fn to_xml(&self) -> String {
        format!(
            r#"<samlp:AuthnRequest 
                xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol"
                xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
                ID="{}"
                Version="2.0"
                IssueInstant="{}"
                Destination="{}"
                ProtocolBinding="{}"
                AssertionConsumerServiceURL="{}"
                ForceAuthn="{}">
                <saml:Issuer>{}</saml:Issuer>
            </samlp:AuthnRequest>"#,
            self.id,
            self.issue_instant.to_rfc3339(),
            self.destination,
            self.protocol_binding,
            self.acs_url,
            self.force_authn,
            self.issuer
        )
    }
}

/// SAML Response
#[derive(Debug, Deserialize)]
pub struct SamlResponse {
    /// Response status
    pub status: ResponseStatus,
    /// Assertions
    pub assertions: Vec<Assertion>,
    /// In response to request ID
    pub in_response_to: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct ResponseStatus {
    /// Status code
    pub code: String,
    /// Status message
    pub message: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct Assertion {
    /// Subject information
    pub subject: Subject,
    /// Attributes
    pub attributes: Vec<Attribute>,
    /// Conditions
    pub conditions: Option<Conditions>,
    /// Authentication statement
    pub authn_statement: Option<AuthnStatement>,
}

#[derive(Debug, Deserialize)]
pub struct Subject {
    /// Name ID
    pub name_id: String,
    /// Name ID format
    pub format: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct Attribute {
    /// Attribute name
    pub name: String,
    /// Attribute values
    pub values: Vec<String>,
}

#[derive(Debug, Deserialize)]
pub struct Conditions {
    /// Not before time
    pub not_before: Option<DateTime<Utc>>,
    /// Not on or after time
    pub not_on_or_after: Option<DateTime<Utc>>,
}

#[derive(Debug, Deserialize)]
pub struct AuthnStatement {
    /// Session index
    pub session_index: Option<String>,
    /// Authentication instant
    pub authn_instant: DateTime<Utc>,
}

impl SamlProvider {
    /// Create a new SAML provider
    pub fn new(config: SamlConfig) -> Self {
        Self {
            config,
            sessions: Arc::new(RwLock::new(HashMap::new())),
            pending_requests: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    /// Generate login URL
    pub async fn generate_login_url(&self, relay_state: Option<String>) -> FusekiResult<Url> {
        let request = AuthnRequest::new(&self.config);
        let request_xml = request.to_xml();

        // Store pending request
        let pending = PendingRequest {
            id: request.id.clone(),
            relay_state,
            timestamp: SystemTime::now(),
        };

        let relay_state_clone = pending.relay_state.clone();
        let mut pending_requests = self.pending_requests.write().await;
        pending_requests.insert(request.id.clone(), pending);

        // Encode request
        let encoded = general_purpose::STANDARD.encode(request_xml.as_bytes());

        // Build redirect URL
        let mut url = self.config.idp.sso_url.clone();
        url.query_pairs_mut().append_pair("SAMLRequest", &encoded);

        if let Some(relay) = &relay_state_clone {
            url.query_pairs_mut().append_pair("RelayState", relay);
        }

        Ok(url)
    }

    /// Process SAML response
    pub async fn process_response(
        &self,
        saml_response: &str,
        relay_state: Option<&str>,
    ) -> FusekiResult<User> {
        // Decode response
        let decoded = general_purpose::STANDARD
            .decode(saml_response)
            .map_err(|e| {
                FusekiError::authentication(format!("Failed to decode SAML response: {}", e))
            })?;

        let response_xml = String::from_utf8(decoded).map_err(|e| {
            FusekiError::authentication(format!("Invalid UTF-8 in SAML response: {}", e))
        })?;

        // Parse and validate response
        let response = self.parse_response(&response_xml)?;
        self.validate_response(&response)?;

        // Extract user information
        let user = self.extract_user_info(&response)?;

        // Create session
        let session = SamlSession {
            user: user.clone(),
            session_index: response
                .assertions
                .first()
                .and_then(|a| a.authn_statement.as_ref())
                .and_then(|s| s.session_index.clone()),
            created_at: SystemTime::now(),
            expires_at: SystemTime::now() + self.config.session.timeout,
            attributes: self.extract_attributes(&response),
        };

        // Store session
        let session_id = Uuid::new_v4().to_string();
        let mut sessions = self.sessions.write().await;
        sessions.insert(session_id, session);

        // Clean up pending request
        if let Some(in_response_to) = &response.in_response_to {
            let mut pending = self.pending_requests.write().await;
            pending.remove(in_response_to);
        }

        Ok(user)
    }

    /// Parse SAML response XML
    fn parse_response(&self, _xml: &str) -> FusekiResult<SamlResponse> {
        // TODO: Implement proper XML parsing with xmlsec
        // For now, return a dummy response
        Err(FusekiError::service_unavailable(
            "SAML response parsing not yet implemented",
        ))
    }

    /// Validate SAML response
    fn validate_response(&self, response: &SamlResponse) -> FusekiResult<()> {
        // Check status
        if response.status.code != "urn:oasis:names:tc:SAML:2.0:status:Success" {
            return Err(FusekiError::authentication(format!(
                "SAML authentication failed: {}",
                response
                    .status
                    .message
                    .as_ref()
                    .unwrap_or(&"Unknown error".to_string())
            )));
        }

        // Validate assertions
        if response.assertions.is_empty() {
            return Err(FusekiError::authentication(
                "No assertions in SAML response",
            ));
        }

        // Check conditions
        for assertion in &response.assertions {
            if let Some(conditions) = &assertion.conditions {
                let now = Utc::now();

                if let Some(not_before) = &conditions.not_before {
                    if now < *not_before {
                        return Err(FusekiError::authentication("SAML assertion not yet valid"));
                    }
                }

                if let Some(not_after) = &conditions.not_on_or_after {
                    if now >= *not_after {
                        return Err(FusekiError::authentication("SAML assertion expired"));
                    }
                }
            }
        }

        // TODO: Verify signature

        Ok(())
    }

    /// Extract user information from SAML response
    fn extract_user_info(&self, response: &SamlResponse) -> FusekiResult<User> {
        let assertion = response
            .assertions
            .first()
            .ok_or_else(|| FusekiError::authentication("No assertion found"))?;

        let mut user = User {
            username: assertion.subject.name_id.clone(),
            email: None,
            full_name: None,
            roles: vec!["user".to_string()],
            last_login: Some(chrono::Utc::now()),
            permissions: vec![],
        };

        // Map attributes
        for attr in &assertion.attributes {
            if attr.name == self.config.attribute_mapping.username && !attr.values.is_empty() {
                user.username = attr.values[0].clone();
            }

            if let Some(email_attr) = &self.config.attribute_mapping.email {
                if attr.name == *email_attr && !attr.values.is_empty() {
                    user.email = Some(attr.values[0].clone());
                }
            }

            if let Some(display_attr) = &self.config.attribute_mapping.display_name {
                if attr.name == *display_attr && !attr.values.is_empty() {
                    user.full_name = Some(attr.values[0].clone());
                }
            }

            if let Some(groups_attr) = &self.config.attribute_mapping.groups {
                if attr.name == *groups_attr {
                    // Map groups to roles
                    for group in &attr.values {
                        match group.as_str() {
                            "admin" | "administrators" => user.roles.push("admin".to_string()),
                            "editor" | "editors" => user.roles.push("editor".to_string()),
                            _ => {}
                        }
                    }
                }
            }

            // Note: User struct doesn't have attributes field, so we skip storing them
        }

        Ok(user)
    }

    /// Extract all attributes from response
    fn extract_attributes(&self, response: &SamlResponse) -> HashMap<String, Vec<String>> {
        let mut attributes = HashMap::new();

        for assertion in &response.assertions {
            for attr in &assertion.attributes {
                attributes.insert(attr.name.clone(), attr.values.clone());
            }
        }

        attributes
    }

    /// Generate logout URL
    pub async fn generate_logout_url(&self, user: &User) -> FusekiResult<Option<Url>> {
        if let Some(slo_url) = &self.config.idp.slo_url {
            // TODO: Generate proper logout request
            Ok(Some(slo_url.clone()))
        } else {
            Ok(None)
        }
    }

    /// Clean up expired sessions
    pub async fn cleanup_sessions(&self) {
        let mut sessions = self.sessions.write().await;
        let now = SystemTime::now();

        sessions.retain(|_, session| session.expires_at > now);

        // Also clean up old pending requests
        let mut pending = self.pending_requests.write().await;
        let timeout = Duration::from_secs(300); // 5 minutes

        pending.retain(|_, request| {
            now.duration_since(request.timestamp)
                .unwrap_or(Duration::MAX)
                < timeout
        });
    }

    /// Get session ID by SAML session index
    pub async fn get_session_by_index(&self, session_index: &str) -> FusekiResult<Option<String>> {
        let sessions = self.sessions.read().await;

        for (session_id, session) in sessions.iter() {
            if let Some(index) = &session.session_index {
                if index == session_index {
                    return Ok(Some(session_id.clone()));
                }
            }
        }

        Ok(None)
    }

    /// Generate SAML logout request
    pub async fn generate_logout_request(
        &self,
        session_index: &str,
        name_id: &str,
    ) -> FusekiResult<String> {
        let slo_url = self
            .config
            .idp
            .slo_url
            .as_ref()
            .ok_or_else(|| FusekiError::configuration("SAML SLO not configured"))?;

        // Generate logout request XML
        let request_id = format!("_{}", Uuid::new_v4());
        let logout_request = format!(
            r#"<?xml version="1.0" encoding="UTF-8"?>
<samlp:LogoutRequest
    xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol"
    xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
    ID="{}"
    Version="2.0"
    IssueInstant="{}"
    Destination="{}">
    <saml:Issuer>{}</saml:Issuer>
    <saml:NameID>{}</saml:NameID>
    <samlp:SessionIndex>{}</samlp:SessionIndex>
</samlp:LogoutRequest>"#,
            request_id,
            chrono::Utc::now().to_rfc3339(),
            slo_url,
            self.config.sp.entity_id,
            name_id,
            session_index
        );

        // Encode the request
        let encoded = general_purpose::STANDARD.encode(logout_request.as_bytes());

        // Build the logout URL
        let mut logout_url = slo_url.clone();
        logout_url
            .query_pairs_mut()
            .append_pair("SAMLRequest", &encoded);

        Ok(logout_url.to_string())
    }

    /// Get SAML metadata XML
    pub fn get_metadata(&self) -> String {
        format!(
            r#"<?xml version="1.0" encoding="UTF-8"?>
<md:EntityDescriptor xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata"
                     entityID="{}">
  <md:SPSSODescriptor AuthnRequestsSigned="false" WantAssertionsSigned="true"
                      protocolSupportEnumeration="urn:oasis:names:tc:SAML:2.0:protocol">
    <md:NameIDFormat>urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress</md:NameIDFormat>
    <md:AssertionConsumerService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST"
                                 Location="{}" index="1" isDefault="true"/>
    {}
  </md:SPSSODescriptor>
</md:EntityDescriptor>"#,
            self.config.sp.entity_id,
            self.config.sp.acs_url,
            self.config.sp.sls_url.as_ref()
                .map(|url| format!(r#"<md:SingleLogoutService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect" Location="{}"/>"#, url))
                .unwrap_or_default()
        )
    }
}

impl SamlProvider {
    /// Authenticate user with username/password (not applicable for SAML)
    pub async fn authenticate(&self, _username: &str, _password: &str) -> FusekiResult<AuthResult> {
        // SAML doesn't use username/password authentication
        Ok(AuthResult::Invalid)
    }

    /// Validate SAML session token
    pub async fn validate_token(&self, token: &str) -> FusekiResult<AuthResult> {
        let sessions = self.sessions.read().await;

        if let Some(session) = sessions.get(token) {
            if session.expires_at > SystemTime::now() {
                Ok(AuthResult::Authenticated(session.user.clone()))
            } else {
                Ok(AuthResult::Expired)
            }
        } else {
            Ok(AuthResult::Invalid)
        }
    }

    /// Refresh token (not applicable for SAML)
    pub async fn refresh_token(&self, _token: &str) -> FusekiResult<String> {
        // SAML doesn't support token refresh - need to re-authenticate
        Err(FusekiError::bad_request(
            "SAML does not support token refresh",
        ))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_authn_request_generation() {
        let config = SamlConfig {
            sp: ServiceProviderConfig {
                entity_id: "http://sp.example.com".to_string(),
                acs_url: Url::parse("http://sp.example.com/acs").unwrap(),
                sls_url: None,
                certificate: None,
                private_key: None,
            },
            idp: IdentityProviderConfig {
                entity_id: "http://idp.example.com".to_string(),
                sso_url: Url::parse("http://idp.example.com/sso").unwrap(),
                slo_url: None,
                certificate: "dummy-cert".to_string(),
                metadata_url: None,
            },
            attribute_mapping: AttributeMapping::default(),
            session: SessionConfig::default(),
        };

        let request = AuthnRequest::new(&config);
        let xml = request.to_xml();

        assert!(xml.contains(&config.sp.entity_id));
        assert!(xml.contains(&config.sp.acs_url.to_string()));
    }

    #[test]
    fn test_attribute_mapping() {
        let mapping = AttributeMapping::default();
        assert_eq!(
            mapping.username,
            "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name"
        );
        assert!(mapping.email.is_some());
    }
}