monosecret 0.3.1

use std::borrow::Cow;
use std::collections::HashMap;
use std::sync::Arc;
use std::sync::LazyLock;
use std::sync::Mutex;
use std::sync::OnceLock;

use secrecy::SecretString;

use super::Address;
use super::DiscoveryContext;
use super::ProducedValuePersistence;
use super::Provider;
use super::ProviderCredentials;
use crate::MonosecretError;
use crate::Result;
use crate::config::NativeAddress;

/// Return type from provider factories that pairs a provider with an
/// optional preflight check (e.g. authentication verification).
pub(crate) struct ProviderWithPreflight {
	pub provider: Box<dyn Provider>,
	pub preflight: Option<Box<dyn Fn() -> Result<()> + Send + Sync>>,
}

/// Process-wide deduplication of provider auth probes.
///
/// Caching the preflight check per provider *instance* was enough when one
/// instance served every secret, but a secret's `providers` fallback chain
/// builds a fresh instance per (secret, URI) pair, so N secrets would run N
/// identical auth probes (each a CLI round-trip). Providers whose auth state is
/// shared across instances advertise that via [`Provider::auth_scope_key`], and
/// [`PreflightGuard`] keys their probe here instead: the first caller per key
/// runs it, concurrent callers block on the same cell, and later callers
/// reuse the result.
///
/// Failures are returned to every caller waiting on the in-flight probe but
/// are not cached beyond that: the user may fix auth mid-process (e.g. unlock
/// the desktop app in a long-lived SDK process), so the next check re-probes.
type AuthCheckResult = std::result::Result<(), String>;
type AuthCheckCell = Arc<OnceLock<AuthCheckResult>>;

pub(crate) struct AuthCheckCache<K> {
	cells: Mutex<HashMap<K, AuthCheckCell>>,
}

impl<K> Default for AuthCheckCache<K> {
	fn default() -> Self {
		Self {
			cells: Mutex::new(HashMap::new()),
		}
	}
}

impl<K: std::hash::Hash + Eq + Clone> AuthCheckCache<K> {
	pub(crate) fn check(
		&self,
		key: K,
		probe: impl FnOnce() -> std::result::Result<(), String>,
	) -> std::result::Result<(), String> {
		let cell = self
			.cells
			.lock()
			.unwrap()
			.entry(key.clone())
			.or_default()
			.clone();
		let result = cell.get_or_init(probe).clone();
		if result.is_err() {
			// Drop the failed cell so a later retry re-probes, but only if it
			// is still ours: another thread may have already replaced it.
			let mut cells = self.cells.lock().unwrap();
			if let Some(existing) = cells.get(&key)
				&& Arc::ptr_eq(existing, &cell)
			{
				cells.remove(&key);
			}
		}
		result
	}
}

/// Auth probes shared across provider instances (see
/// [`Provider::auth_scope_key`]), keyed by provider name plus scope.
static PREFLIGHT_AUTH_CACHE: LazyLock<AuthCheckCache<(&'static str, String)>> =
	LazyLock::new(AuthCheckCache::default);

/// Wrapper that runs a preflight check exactly once before any provider
/// operation, caching the result for all subsequent calls.
pub(super) struct PreflightGuard {
	inner: Box<dyn Provider>,
	preflight: Option<Box<dyn Fn() -> Result<()> + Send + Sync>>,
	result: OnceLock<std::result::Result<(), String>>,
}

impl PreflightGuard {
	pub(super) fn new(pwp: ProviderWithPreflight) -> Self {
		Self {
			inner: pwp.provider,
			preflight: pwp.preflight,
			result: OnceLock::new(),
		}
	}

	fn check(&self) -> Result<()> {
		let Some(f) = &self.preflight else {
			return Ok(());
		};
		// A provider with a shared auth scope dedupes the probe process-wide
		// in PREFLIGHT_AUTH_CACHE, so the per-instance providers that a
		// secret's `providers` chain creates all reuse one probe.
		if let Some(scope) = self.inner.auth_scope_key() {
			return PREFLIGHT_AUTH_CACHE
				.check((self.inner.name(), scope), || {
					f().map_err(|e| crate::error::display_error_chain(&e))
				})
				.map_err(MonosecretError::ProviderOperationFailed);
		}
		let result = self
			.result
			.get_or_init(|| f().map_err(|e| crate::error::display_error_chain(&e)));
		match result {
			Ok(()) => Ok(()),
			Err(msg) => Err(MonosecretError::ProviderOperationFailed(msg.clone())),
		}
	}
}

impl Provider for PreflightGuard {
	fn convention_address(&self, project: &str, profile: &str, key: &str) -> Result<NativeAddress> {
		// Pure naming, no I/O: needs no auth preflight.
		self.inner.convention_address(project, profile, key)
	}

	fn supported_coords(&self) -> &'static [&'static str] {
		self.inner.supported_coords()
	}

	fn resolve_coords<'a>(&self, addr: Address<'a>) -> Result<Cow<'a, NativeAddress>> {
		// Pure naming, no I/O: needs no auth preflight.
		self.inner.resolve_coords(addr)
	}

	fn entry_coordinates<'a>(&self, addr: Address<'a>) -> Result<Cow<'a, NativeAddress>> {
		// Pure naming, no I/O: needs no auth preflight.
		self.inner.entry_coordinates(addr)
	}

	fn get(&self, addr: Address<'_>) -> Result<Option<SecretString>> {
		self.check()?;
		self.inner.get(addr)
	}

	fn set(&self, addr: Address<'_>, value: &SecretString) -> Result<()> {
		self.check()?;
		self.inner.set(addr, value)
	}

	/// Forwarded rather than left to the trait default, which would call
	/// `self.set` and drop the expiry the inner provider can honor.
	fn set_expiring(
		&self,
		addr: Address<'_>,
		value: &SecretString,
		max_age: std::time::Duration,
	) -> Result<()> {
		self.check()?;
		self.inner.set_expiring(addr, value, max_age)
	}

	fn delete(&self, addr: Address<'_>) -> Result<bool> {
		self.check()?;
		self.inner.delete(addr)
	}

	fn supports_delete(&self) -> bool {
		self.inner.supports_delete()
	}

	fn check_deletable(&self, addr: Address<'_>) -> Result<()> {
		self.inner.check_deletable(addr)
	}

	fn check_writable(&self, addr: Address<'_>) -> Result<()> {
		self.inner.check_writable(addr)
	}

	fn generated_value_persistence(&self) -> ProducedValuePersistence {
		// Capability inspection is pure and must not trigger authentication.
		self.inner.generated_value_persistence()
	}

	fn prompted_value_persistence(&self) -> ProducedValuePersistence {
		// Capability inspection is pure and must not trigger authentication.
		self.inner.prompted_value_persistence()
	}

	fn describe_write_target(&self, addr: Address<'_>) -> Result<String> {
		self.inner.describe_write_target(addr)
	}

	fn auth_scope_key(&self) -> Option<String> {
		self.inner.auth_scope_key()
	}

	fn name(&self) -> &'static str {
		self.inner.name()
	}

	fn uri(&self) -> String {
		self.inner.uri()
	}

	fn same_entry(&self, other: &dyn Provider, addr: Address<'_>) -> Result<bool> {
		self.inner.same_entry(other, addr)
	}

	fn same_entries(
		&self,
		self_addr: Address<'_>,
		other: &dyn Provider,
		other_addr: Address<'_>,
	) -> Result<bool> {
		self.inner.same_entries(self_addr, other, other_addr)
	}

	fn storage_identity(&self) -> String {
		self.inner.storage_identity()
	}

	fn entry_container_identity(&self) -> String {
		self.inner.entry_container_identity()
	}

	fn physical_store_path(&self) -> Option<&std::path::Path> {
		self.inner.physical_store_path()
	}

	fn set_reason(&self, reason: Option<String>) {
		self.inner.set_reason(reason);
	}

	fn set_caller(&self, caller: Option<crate::CallerContext>) {
		self.inner.set_caller(caller);
	}

	fn set_profile(&self, profile: &str) {
		self.inner.set_profile(profile);
	}

	fn with_base_dir(&mut self, base_dir: &std::path::Path) {
		self.inner.with_base_dir(base_dir);
	}

	fn with_credentials(&mut self, credentials: ProviderCredentials) {
		self.inner.with_credentials(credentials);
	}

	fn reflect(&self, context: DiscoveryContext<'_>) -> Result<HashMap<String, crate::Secret>> {
		self.check()?;
		self.inner.reflect(context)
	}

	fn get_many(&self, requests: &[(&str, Address<'_>)]) -> Result<HashMap<String, SecretString>> {
		self.check()?;
		self.inner.get_many(requests)
	}
}

#[cfg(test)]
mod tests {
	use std::cell::Cell;
	use std::sync::Arc;
	use std::sync::Mutex;

	use secrecy::SecretString;

	use super::AuthCheckCache;
	use super::PreflightGuard;
	use super::ProviderWithPreflight;
	use crate::Result;
	use crate::config::NativeAddress;
	use crate::provider::Address;
	use crate::provider::Provider;

	struct ProfileRecordingProvider {
		profile: Arc<Mutex<Option<String>>>,
	}

	impl Provider for ProfileRecordingProvider {
		fn convention_address(
			&self,
			_project: &str,
			_profile: &str,
			key: &str,
		) -> Result<NativeAddress> {
			Ok(NativeAddress {
				item: key.to_string(),
				..Default::default()
			})
		}

		fn get(&self, _addr: Address<'_>) -> Result<Option<SecretString>> {
			Ok(None)
		}

		fn set(&self, _addr: Address<'_>, _value: &SecretString) -> Result<()> {
			Ok(())
		}

		fn name(&self) -> &'static str {
			"profile-recording"
		}

		fn uri(&self) -> String {
			"profile-recording://".to_string()
		}

		fn set_profile(&self, profile: &str) {
			*self.profile.lock().unwrap() = Some(profile.to_string());
		}
	}

	#[test]
	fn success_probes_once_per_key() {
		let cache = AuthCheckCache::default();
		let probes = Cell::new(0);
		for _ in 0..3 {
			let result = cache.check("key", || {
				probes.set(probes.get() + 1);
				Ok(())
			});
			assert_eq!(result, Ok(()));
		}
		assert_eq!(probes.get(), 1);
	}

	#[test]
	fn failure_is_not_cached() {
		let cache = AuthCheckCache::default();
		assert_eq!(
			cache.check("key", || Err("not signed in".to_string())),
			Err("not signed in".to_string())
		);
		assert_eq!(cache.check("key", || Ok(())), Ok(()));

		let probes = Cell::new(0);
		assert_eq!(
			cache.check("key", || {
				probes.set(probes.get() + 1);
				Ok(())
			}),
			Ok(())
		);
		assert_eq!(probes.get(), 0);
	}

	#[test]
	fn keys_are_independent() {
		let cache = AuthCheckCache::default();
		assert_eq!(cache.check("a", || Ok(())), Ok(()));
		assert_eq!(
			cache.check("b", || Err("nope".to_string())),
			Err("nope".to_string())
		);
		assert_eq!(cache.check("a", || Err("unused".to_string())), Ok(()));
	}

	#[test]
	fn set_profile_reaches_the_provider_through_preflight_guard() {
		let profile = Arc::new(Mutex::new(None));
		let guard = PreflightGuard::new(ProviderWithPreflight {
			provider: Box::new(ProfileRecordingProvider {
				profile: Arc::clone(&profile),
			}),
			preflight: Some(Box::new(|| panic!("set_profile must not run preflight"))),
		});

		guard.set_profile("production");

		assert_eq!(profile.lock().unwrap().as_deref(), Some("production"));
	}
}