use std::marker::PhantomData;

use crate::lockable::{Lockable, OwnedLockable, RawLock, Sharable};
use crate::Keyable;

use super::{utils, LockGuard, OwnedLockCollection};

fn get_locks<L: Lockable>(data: &L) -> Vec<&dyn RawLock> {
	let mut locks = Vec::new();
	data.get_ptrs(&mut locks);
	locks
}

unsafe impl<L: Lockable + Send + Sync> RawLock for OwnedLockCollection<L> {
	unsafe fn lock(&self) {
		let locks = get_locks(&self.data);
		for lock in locks {
			lock.lock();
		}
	}

	unsafe fn try_lock(&self) -> bool {
		let locks = get_locks(&self.data);
		utils::ordered_try_lock(&locks)
	}

	unsafe fn unlock(&self) {
		let locks = get_locks(&self.data);
		for lock in locks {
			lock.unlock();
		}
	}

	unsafe fn read(&self) {
		let locks = get_locks(&self.data);
		for lock in locks {
			lock.read();
		}
	}

	unsafe fn try_read(&self) -> bool {
		let locks = get_locks(&self.data);
		utils::ordered_try_read(&locks)
	}

	unsafe fn unlock_read(&self) {
		let locks = get_locks(&self.data);
		for lock in locks {
			lock.unlock_read();
		}
	}
}

unsafe impl<L: Lockable> Lockable for OwnedLockCollection<L> {
	type Guard<'g> = L::Guard<'g> where Self: 'g;

	type ReadGuard<'g> = L::ReadGuard<'g> where Self: 'g;

	fn get_ptrs<'a>(&'a self, ptrs: &mut Vec<&'a dyn RawLock>) {
		self.data.get_ptrs(ptrs)
	}

	unsafe fn guard(&self) -> Self::Guard<'_> {
		self.data.guard()
	}

	unsafe fn read_guard(&self) -> Self::ReadGuard<'_> {
		self.data.read_guard()
	}
}

unsafe impl<L: Sharable> Sharable for OwnedLockCollection<L> {}

unsafe impl<L: OwnedLockable> OwnedLockable for OwnedLockCollection<L> {}

impl<L> IntoIterator for OwnedLockCollection<L>
where
	L: IntoIterator,
{
	type Item = <L as IntoIterator>::Item;
	type IntoIter = <L as IntoIterator>::IntoIter;

	fn into_iter(self) -> Self::IntoIter {
		self.data.into_iter()
	}
}

impl<L: OwnedLockable, I: FromIterator<L> + OwnedLockable> FromIterator<L>
	for OwnedLockCollection<I>
{
	fn from_iter<T: IntoIterator<Item = L>>(iter: T) -> Self {
		let iter: I = iter.into_iter().collect();
		Self::new(iter)
	}
}

impl<E: OwnedLockable + Extend<L>, L: OwnedLockable> Extend<L> for OwnedLockCollection<E> {
	fn extend<T: IntoIterator<Item = L>>(&mut self, iter: T) {
		self.data.extend(iter)
	}
}

impl<L: OwnedLockable> AsMut<L> for OwnedLockCollection<L> {
	fn as_mut(&mut self) -> &mut L {
		&mut self.data
	}
}

impl<L: OwnedLockable + Default> Default for OwnedLockCollection<L> {
	fn default() -> Self {
		Self::new(L::default())
	}
}

impl<L: OwnedLockable> From<L> for OwnedLockCollection<L> {
	fn from(value: L) -> Self {
		Self::new(value)
	}
}

impl<L: OwnedLockable> OwnedLockCollection<L> {
	/// Creates a new collection of owned locks.
	///
	/// Because the locks are owned, there's no need to do any checks for
	/// duplicate values. The locks also don't need to be sorted by memory
	/// address because they aren't used anywhere else.
	///
	/// # Examples
	///
	/// ```
	/// use happylock::Mutex;
	/// use happylock::collection::OwnedLockCollection;
	///
	/// let data = (Mutex::new(0), Mutex::new(""));
	/// let lock = OwnedLockCollection::new(data);
	/// ```
	#[must_use]
	pub const fn new(data: L) -> Self {
		Self { data }
	}

	/// Gets the underlying collection, consuming this collection.
	///
	/// # Examples
	///
	/// ```
	/// use happylock::{Mutex, ThreadKey};
	/// use happylock::collection::OwnedLockCollection;
	///
	/// let data = (Mutex::new(42), Mutex::new(""));
	/// let lock = OwnedLockCollection::new(data);
	///
	/// let key = ThreadKey::get().unwrap();
	/// let inner = lock.into_inner();
	/// let guard = inner.0.lock(key);
	/// assert_eq!(*guard, 42);
	/// ```
	#[must_use]
	pub fn into_inner(self) -> L {
		self.data
	}

	/// Locks the collection
	///
	/// This function returns a guard that can be used to access the underlying
	/// data. When the guard is dropped, the locks in the collection are also
	/// dropped.
	///
	/// # Examples
	///
	/// ```
	/// use happylock::{Mutex, ThreadKey};
	/// use happylock::collection::OwnedLockCollection;
	///
	/// let key = ThreadKey::get().unwrap();
	/// let data = (Mutex::new(0), Mutex::new(""));
	/// let lock = OwnedLockCollection::new(data);
	///
	/// let mut guard = lock.lock(key);
	/// *guard.0 += 1;
	/// *guard.1 = "1";
	/// ```
	pub fn lock<'g, 'key, Key: Keyable + 'key>(
		&'g self,
		key: Key,
	) -> LockGuard<'key, L::Guard<'g>, Key> {
		let locks = get_locks(&self.data);
		for lock in locks {
			// safety: we have the thread key, and these locks happen in a
			//         predetermined order
			unsafe { lock.lock() };
		}

		// safety: we've locked all of this already
		let guard = unsafe { self.data.guard() };
		LockGuard {
			guard,
			key,
			_phantom: PhantomData,
		}
	}

	/// Attempts to lock the without blocking.
	///
	/// If successful, this method returns a guard that can be used to access
	/// the data, and unlocks the data when it is dropped. Otherwise, `None` is
	/// returned.
	///
	/// # Examples
	///
	/// ```
	/// use happylock::{Mutex, ThreadKey};
	/// use happylock::collection::OwnedLockCollection;
	///
	/// let key = ThreadKey::get().unwrap();
	/// let data = (Mutex::new(0), Mutex::new(""));
	/// let lock = OwnedLockCollection::new(data);
	///
	/// match lock.try_lock(key) {
	///     Some(mut guard) => {
	///         *guard.0 += 1;
	///         *guard.1 = "1";
	///     },
	///     None => unreachable!(),
	/// };
	///
	/// ```
	pub fn try_lock<'g, 'key: 'g, Key: Keyable + 'key>(
		&'g self,
		key: Key,
	) -> Option<LockGuard<'key, L::Guard<'g>, Key>> {
		let locks = get_locks(&self.data);
		let guard = unsafe {
			if !utils::ordered_try_lock(&locks) {
				return None;
			}

			// safety: we've acquired the locks
			self.data.guard()
		};

		Some(LockGuard {
			guard,
			key,
			_phantom: PhantomData,
		})
	}

	/// Unlocks the underlying lockable data type, returning the key that's
	/// associated with it.
	///
	/// # Examples
	///
	/// ```
	/// use happylock::{Mutex, ThreadKey};
	/// use happylock::collection::OwnedLockCollection;
	///
	/// let key = ThreadKey::get().unwrap();
	/// let data = (Mutex::new(0), Mutex::new(""));
	/// let lock = OwnedLockCollection::new(data);
	///
	/// let mut guard = lock.lock(key);
	/// *guard.0 += 1;
	/// *guard.1 = "1";
	/// let key = OwnedLockCollection::<(Mutex<i32>, Mutex<&str>)>::unlock(guard);
	/// ```
	#[allow(clippy::missing_const_for_fn)]
	pub fn unlock<'g, 'key: 'g, Key: Keyable + 'key>(
		guard: LockGuard<'key, L::Guard<'g>, Key>,
	) -> Key {
		drop(guard.guard);
		guard.key
	}
}

impl<L: Sharable> OwnedLockCollection<L> {
	/// Locks the collection, so that other threads can still read from it
	///
	/// This function returns a guard that can be used to access the underlying
	/// data immutably. When the guard is dropped, the locks in the collection
	/// are also dropped.
	///
	/// # Examples
	///
	/// ```
	/// use happylock::{RwLock, ThreadKey};
	/// use happylock::collection::OwnedLockCollection;
	///
	/// let key = ThreadKey::get().unwrap();
	/// let data = (RwLock::new(0), RwLock::new(""));
	/// let lock = OwnedLockCollection::new(data);
	///
	/// let mut guard = lock.read(key);
	/// assert_eq!(*guard.0, 0);
	/// assert_eq!(*guard.1, "");
	/// ```
	pub fn read<'g, 'key, Key: Keyable + 'key>(
		&'g self,
		key: Key,
	) -> LockGuard<'key, L::ReadGuard<'g>, Key> {
		let locks = get_locks(&self.data);
		for lock in locks {
			// safety: we have the thread key, and these locks happen in a
			//         predetermined order
			unsafe { lock.read() };
		}

		// safety: we've locked all of this already
		let guard = unsafe { self.data.read_guard() };
		LockGuard {
			guard,
			key,
			_phantom: PhantomData,
		}
	}

	/// Attempts to lock the without blocking, in such a way that other threads
	/// can still read from the collection.
	///
	/// If successful, this method returns a guard that can be used to access
	/// the data immutably, and unlocks the data when it is dropped. Otherwise,
	/// `None` is returned.
	///
	/// # Examples
	///
	/// ```
	/// use happylock::{RwLock, ThreadKey};
	/// use happylock::collection::OwnedLockCollection;
	///
	/// let key = ThreadKey::get().unwrap();
	/// let data = (RwLock::new(5), RwLock::new("6"));
	/// let lock = OwnedLockCollection::new(data);
	///
	/// match lock.try_read(key) {
	///     Some(mut guard) => {
	///         assert_eq!(*guard.0, 5);
	///         assert_eq!(*guard.1, "6");
	///     },
	///     None => unreachable!(),
	/// };
	///
	/// ```
	pub fn try_read<'g, 'key: 'g, Key: Keyable + 'key>(
		&'g self,
		key: Key,
	) -> Option<LockGuard<'key, L::ReadGuard<'g>, Key>> {
		let locks = get_locks(&self.data);
		let guard = unsafe {
			if !utils::ordered_try_read(&locks) {
				return None;
			}

			// safety: we've acquired the locks
			self.data.read_guard()
		};

		Some(LockGuard {
			guard,
			key,
			_phantom: PhantomData,
		})
	}

	/// Unlocks the underlying lockable data type, returning the key that's
	/// associated with it.
	///
	/// # Examples
	///
	/// ```
	/// use happylock::{RwLock, ThreadKey};
	/// use happylock::collection::OwnedLockCollection;
	///
	/// let key = ThreadKey::get().unwrap();
	/// let data = (RwLock::new(0), RwLock::new(""));
	/// let lock = OwnedLockCollection::new(data);
	///
	/// let mut guard = lock.read(key);
	/// let key = OwnedLockCollection::<(RwLock<i32>, RwLock<&str>)>::unlock_read(guard);
	/// ```
	#[allow(clippy::missing_const_for_fn)]
	pub fn unlock_read<'g, 'key: 'g, Key: Keyable + 'key>(
		guard: LockGuard<'key, L::ReadGuard<'g>, Key>,
	) -> Key {
		drop(guard.guard);
		guard.key
	}
}