//! Authentication: `AuthContext`, `Identity`, `IdentityProvider`, `AuthToken`,
//! `ConfigIdentityProvider`.
//!
//! See `docs/architecture/crates/core/auth.md` for the full specification.

use std::collections::HashMap;
use std::net::SocketAddr;
use std::sync::Arc;

use arc_swap::ArcSwap;

use crate::config::DynamicConfig;

#[derive(Debug, Clone, PartialEq)]
pub struct Identity {
    pub id: String,
    pub scopes: Vec<String>,
    pub resources: HashMap<String, Vec<String>>,
}

#[derive(Debug, Clone)]
pub struct AuthToken {
    pub raw: Vec<u8>,
}

#[derive(Clone)]
pub struct AuthContext {
    pub identity: Option<Identity>,
    pub alpn: Vec<u8>,
    pub remote_addr: Option<SocketAddr>,
    pub tls_client_fingerprint: Option<String>,
}

pub trait IdentityProvider: Send + Sync + 'static {
    fn resolve_from_fingerprint(&self, fingerprint: &str) -> Option<Identity>;
    fn resolve_from_token(&self, token: &AuthToken) -> Option<Identity>;
}

pub struct ConfigIdentityProvider {
    dynamic: Arc<ArcSwap<DynamicConfig>>,
}

impl ConfigIdentityProvider {
    pub fn new(dynamic: Arc<ArcSwap<DynamicConfig>>) -> Self {
        Self { dynamic }
    }
}

impl IdentityProvider for ConfigIdentityProvider {
    fn resolve_from_fingerprint(&self, fingerprint: &str) -> Option<Identity> {
        let config = self.dynamic.load();
        config.auth.resolve_identity_from_fingerprint(fingerprint)
    }

    fn resolve_from_token(&self, token: &AuthToken) -> Option<Identity> {
        let config = self.dynamic.load();
        let token_str = String::from_utf8_lossy(&token.raw);
        config.auth.resolve_identity_from_token(&token_str)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::config::{ApiKeyEntry, AuthPolicy, DynamicConfig, PeerEntry, RateLimitConfig};

    fn compute_api_key_hash(token: &str) -> String {
        use sha2::{Digest, Sha256};
        let mut hasher = Sha256::new();
        hasher.update(token.as_bytes());
        let result = hasher.finalize();
        format!("sha256:{}", hex::encode(result))
    }

    fn make_provider(
        config: DynamicConfig,
    ) -> (ConfigIdentityProvider, Arc<ArcSwap<DynamicConfig>>) {
        let arc_swap = Arc::new(ArcSwap::new(Arc::new(config)));
        let provider = ConfigIdentityProvider::new(Arc::clone(&arc_swap));
        (provider, arc_swap)
    }

    fn peer_entry_with_fingerprint(peer_id: &str, fingerprint: &str) -> PeerEntry {
        PeerEntry {
            peer_id: peer_id.to_string(),
            fingerprints: vec![fingerprint.to_string()],
            auth_token_hash: None,
            scopes: vec!["relay:connect".to_string()],
            resources: std::collections::HashMap::new(),
            display_name: None,
            enabled: true,
        }
    }

    fn config_with_fingerprint(peer_id: &str, fingerprint: &str) -> DynamicConfig {
        DynamicConfig {
            auth: AuthPolicy {
                peers: vec![peer_entry_with_fingerprint(peer_id, fingerprint)],
                api_keys: Vec::new(),
            },
            rate_limits: RateLimitConfig::default(),
        }
    }

    fn config_with_api_key(entry: ApiKeyEntry) -> DynamicConfig {
        DynamicConfig {
            auth: AuthPolicy {
                peers: Vec::new(),
                api_keys: vec![entry],
            },
            rate_limits: RateLimitConfig::default(),
        }
    }

    #[test]
    fn identity_fields_and_equality() {
        let mut resources = HashMap::new();
        resources.insert(
            "service".to_string(),
            vec!["gitea".to_string(), "registry".to_string()],
        );
        let id = Identity {
            id: "SHA256:abc123".to_string(),
            scopes: vec!["relay:connect".to_string()],
            resources,
        };
        let id2 = id.clone();
        assert_eq!(id, id2);
        assert_eq!(id.id, "SHA256:abc123");
    }

    #[test]
    fn auth_token_is_clone() {
        let token = AuthToken {
            raw: b"alk_test".to_vec(),
        };
        let cloned = token.clone();
        assert_eq!(token.raw, cloned.raw);
    }

    #[test]
    fn auth_context_is_clone() {
        let ctx = AuthContext {
            identity: None,
            alpn: b"alknet/test".to_vec(),
            remote_addr: None,
            tls_client_fingerprint: None,
        };
        let cloned = ctx.clone();
        assert_eq!(cloned.alpn, b"alknet/test");
        assert!(cloned.identity.is_none());
    }

    #[test]
    fn fingerprint_resolution_known_returns_some() {
        let (provider, _) = make_provider(config_with_fingerprint("worker-a", "SHA256:abc123"));
        let identity = provider
            .resolve_from_fingerprint("SHA256:abc123")
            .expect("known fingerprint resolves");
        assert_eq!(identity.id, "worker-a");
        assert_eq!(identity.scopes, vec!["relay:connect".to_string()]);
        assert!(identity.resources.is_empty());
    }

    #[test]
    fn fingerprint_resolution_unknown_returns_none() {
        let (provider, _) = make_provider(config_with_fingerprint("worker-a", "SHA256:abc123"));
        assert!(provider
            .resolve_from_fingerprint("SHA256:unknown")
            .is_none());
    }

    #[test]
    fn fingerprint_resolution_empty_config_returns_none() {
        let (provider, _) = make_provider(DynamicConfig::default());
        assert!(provider
            .resolve_from_fingerprint("SHA256:anything")
            .is_none());
    }

    #[test]
    fn token_resolution_valid_non_expired_returns_some() {
        let token_str = "alk_testsecret123";
        let hash = compute_api_key_hash(token_str);
        let entry = ApiKeyEntry {
            prefix: "alk_test".to_string(),
            hash,
            scopes: vec!["relay:connect".to_string()],
            description: "test key".to_string(),
            expires_at: None,
        };
        let (provider, _) = make_provider(config_with_api_key(entry));
        let token = AuthToken {
            raw: token_str.as_bytes().to_vec(),
        };
        let identity = provider
            .resolve_from_token(&token)
            .expect("valid non-expired token resolves");
        assert_eq!(identity.id, "alk_test");
        assert_eq!(identity.scopes, vec!["relay:connect".to_string()]);
    }

    #[test]
    fn token_resolution_expired_returns_none() {
        let token_str = "alk_testsecret123";
        let hash = compute_api_key_hash(token_str);
        let entry = ApiKeyEntry {
            prefix: "alk_test".to_string(),
            hash,
            scopes: vec!["relay:connect".to_string()],
            description: "expired key".to_string(),
            expires_at: Some(1),
        };
        let (provider, _) = make_provider(config_with_api_key(entry));
        let token = AuthToken {
            raw: token_str.as_bytes().to_vec(),
        };
        assert!(provider.resolve_from_token(&token).is_none());
    }

    #[test]
    fn token_resolution_unknown_returns_none() {
        let token_str = "alk_testsecret123";
        let hash = compute_api_key_hash(token_str);
        let entry = ApiKeyEntry {
            prefix: "alk_test".to_string(),
            hash,
            scopes: vec!["relay:connect".to_string()],
            description: "test key".to_string(),
            expires_at: None,
        };
        let (provider, _) = make_provider(config_with_api_key(entry));
        let token = AuthToken {
            raw: b"alk_unknown".to_vec(),
        };
        assert!(provider.resolve_from_token(&token).is_none());
    }

    #[test]
    fn token_resolution_wrong_hash_returns_none() {
        let entry = ApiKeyEntry {
            prefix: "alk_test".to_string(),
            hash: "sha256:deadbeef".to_string(),
            scopes: vec!["relay:connect".to_string()],
            description: "wrong hash".to_string(),
            expires_at: None,
        };
        let (provider, _) = make_provider(config_with_api_key(entry));
        let token = AuthToken {
            raw: b"alk_testsecret123".to_vec(),
        };
        assert!(provider.resolve_from_token(&token).is_none());
    }

    #[test]
    fn token_resolution_non_alk_prefix_returns_none() {
        let (provider, _) = make_provider(DynamicConfig::default());
        let token = AuthToken {
            raw: b"bearer_token".to_vec(),
        };
        assert!(provider.resolve_from_token(&token).is_none());
    }

    #[test]
    fn config_reload_changes_resolution_immediately() {
        let (provider, arc_swap) = make_provider(DynamicConfig::default());
        assert!(provider.resolve_from_fingerprint("SHA256:abc123").is_none());

        let new_config = config_with_fingerprint("worker-a", "SHA256:abc123");
        arc_swap.store(Arc::new(new_config));

        assert!(provider.resolve_from_fingerprint("SHA256:abc123").is_some());
    }

    #[test]
    fn config_reload_removes_fingerprint_access_immediately() {
        let (provider, arc_swap) =
            make_provider(config_with_fingerprint("worker-a", "SHA256:abc123"));
        assert!(provider.resolve_from_fingerprint("SHA256:abc123").is_some());

        arc_swap.store(Arc::new(DynamicConfig::default()));

        assert!(provider.resolve_from_fingerprint("SHA256:abc123").is_none());
    }

    #[test]
    fn config_reload_handle_reloads_config() {
        use crate::config::ConfigReloadHandle;
        let arc_swap = Arc::new(ArcSwap::new(Arc::new(DynamicConfig::default())));
        let provider = ConfigIdentityProvider::new(Arc::clone(&arc_swap));
        let handle = ConfigReloadHandle::new(arc_swap);

        assert!(provider.resolve_from_fingerprint("SHA256:abc123").is_none());

        handle.reload(config_with_fingerprint("worker-a", "SHA256:abc123"));

        assert!(provider.resolve_from_fingerprint("SHA256:abc123").is_some());
    }
}