minfac 0.1.5

#![doc = include_str!("../README.md")]
#![cfg_attr(not(feature = "std"), no_std)]
extern crate alloc;

use alloc::{boxed::Box, rc::Rc, string::String, vec::Vec};
use core::{any::type_name, cell::RefCell, fmt::Debug, marker::PhantomData};
use std::sync::OnceLock;

use abi_stable::std_types::{RArc, RVec};

use ffi::{
    FfiResult::{self, FfiErr, FfiOk},
    FfiStr,
};
use service_provider_factory::ServiceProviderFactoryBuilder;
use strategy::{Identifyable, Strategy};
use untyped::{ArcAutoFreePointer, AutoFreePointer, FromArcAutoFreePointer, UntypedFn};

mod binary_search;
mod cycle_detection;
mod ffi;
mod lifetime;
mod registrar;
mod resolvable;
mod service_provider;
mod service_provider_factory;
mod shared;
#[cfg(feature = "stable_abi")]
pub mod stable_abi;
mod strategy;
mod untyped;

pub use lifetime::LifetimeError;
pub use resolvable::Resolvable;
pub use service_provider::ServiceIterator;
pub use service_provider::ServiceProvider;
pub use service_provider::WeakServiceProvider;
pub use service_provider_factory::ServiceProviderFactory;
pub use shared::ShareInner;
pub use strategy::AnyStrategy;

use crate::{
    cycle_detection::{CycleChecker, CycleDetectionInserter},
    ffi::FfiUsizeIterator,
    resolvable::SealedResolvable,
};
pub type ServiceCollection = GenericServiceCollection<AnyStrategy>;

type InternalBuildResult<TS> = FfiResult<UntypedFn<TS>, MissingDependencyWithDependee<TS>>;

type AnyPtr = *const ();

/// Handles lifetime errors, which cannot be enforced using the type system. This is the case when:
/// - WeakServiceProvider outlives the `ServiceProvider` its created from
/// - `ServiceIterator<T>`, which owns a `WeakServiceProvider` internally, outlives its `ServiceProvider`
/// - Any shared service outlives its ServiceProvidevaluer
///
/// Ignoring errors is strongly discouraged, but doesn't cause any undefined behavior or memory leaks by the framework.
/// However, leaking context specific services often lead to memory leaks in user code which are difficult to find:
/// All shared references of a `ServiceProvider` are kept alvalueive if the result of a single `provider::get::<AllRegistered<i32>>()` call
/// is leaking it's provider. This can easily happen, if you forget to collect the results into a vector.
/// To prevent these sneaky errors, `ServiceProvider::drop()` ensures that none of it's internals are kept alive when debug_assertions are enabled.
///
/// The default implementation panics, if the std-feature is enabled (on by default). Otherwise this is a no_op
/// For custom implementations, be aware that this function could be called while panicking already.
/// In std, panic!(), when the thread is panicking already, terminates the entire program immediately.
///
/// This variable only exists, if debug_assertions are enabled
#[cfg(debug_assertions)]
pub static mut MINFAC_ERROR_HANDLER: extern "C-unwind" fn(&LifetimeError) =
    lifetime::default_error_handler;

/// Represents a query for the last registered instance of `T`
#[derive(Debug, PartialEq, Eq)]
pub struct Registered<T>(pub T);

/// Represents a query for all registered instances of Type `T`.
pub struct AllRegistered<T>(pub Box<dyn Iterator<Item = T>>);

/// Collection of constructors for different types of services. Registered constructors are never called in this state.
/// Instances can only be received by a ServiceProvider, which can be created by calling `build`
#[repr(C)]
pub struct GenericServiceCollection<TS: Strategy + 'static> {
    strategy: PhantomData<TS>,
    producer_factories: RVec<ServiceProducer<TS>>,
}

/// Alias builder is used to register services, which depend on the previous service.
/// This is especially useful, if the previous service contains an anonymous type like a lambda
pub struct AliasBuilder<'a, T: ?Sized, TS: Strategy + 'static>(
    Rc<RefCell<&'a mut GenericServiceCollection<TS>>>,
    PhantomData<T>,
);

impl<'a, T: Identifyable<TS::Id>, TS: Strategy + 'static> AliasBuilder<'a, T, TS> {
    fn new(col: &'a mut GenericServiceCollection<TS>) -> Self {
        Self(Rc::new(RefCell::new(col)), PhantomData)
    }

    /// Registers an aliased service. The returned AliasBuilder refers to the new type
    /// ``` rust
    /// let mut col = minfac::ServiceCollection::new();
    /// let mut i8alias = col.register(|| 1i8)
    ///     .alias(|a| a as i16 * 2)
    ///     .alias(|a| a as i32 * 2);
    /// let prov = col.build().unwrap();
    /// assert_eq!(Some(2i16), prov.get());
    /// assert_eq!(Some(4i32), prov.get());
    /// ```
    pub fn alias<TNew: Identifyable<TS::Id>>(
        &mut self,
        creator: fn(T) -> TNew,
    ) -> AliasBuilder<'a, TNew, TS> {
        self.0
            .borrow_mut()
            .with::<Registered<T>>()
            .register(creator);
        AliasBuilder::<_, TS>(self.0.clone(), PhantomData)
    }
}

#[repr(C)]
struct ServiceProducer<TS: Strategy + 'static> {
    identifier: TS::Id,
    factory: UntypedFnFactory<TS>,
}

impl<TS: Strategy + 'static> ServiceProducer<TS> {
    fn new<T: Identifyable<TS::Id>>(factory: UntypedFnFactory<TS>) -> Self {
        Self::new_with_type(factory, T::get_id())
    }
    fn new_with_type(factory: UntypedFnFactory<TS>, type_id: TS::Id) -> Self {
        Self {
            identifier: type_id,
            factory,
        }
    }
}

type UntypedFnFactoryCreator<TS> = extern "C" fn(
    outer_context: AutoFreePointer,
    inner_context: &mut UntypedFnFactoryContext<TS>,
) -> InternalBuildResult<TS>;

#[repr(C)]
struct UntypedFnFactory<TS: Strategy + 'static> {
    creator: UntypedFnFactoryCreator<TS>,
    context: AutoFreePointer,
}

impl<TS: Strategy + 'static> UntypedFnFactory<TS> {
    fn no_alloc(context: AnyPtr, creator: UntypedFnFactoryCreator<TS>) -> Self {
        Self {
            creator,
            context: AutoFreePointer::no_alloc(context),
        }
    }
    fn boxed<T>(input: T, creator: UntypedFnFactoryCreator<TS>) -> Self {
        Self {
            creator,
            context: AutoFreePointer::boxed(input),
        }
    }
    fn call(self, ctx: &mut UntypedFnFactoryContext<TS>) -> InternalBuildResult<TS> {
        (self.creator)(self.context, ctx)
    }
}
#[repr(C)]
struct UntypedFnFactoryContext<'a, TS: Strategy + 'static> {
    state_counter: &'a mut usize,
    final_ordered_types: &'a RVec<TS::Id>,
    cyclic_reference_candidates: CycleDetectionInserter<'a>,
}

impl<TS: Strategy + 'static> UntypedFnFactoryContext<'_, TS> {
    fn reserve_state_space(&mut self) -> usize {
        let result: usize = *self.state_counter;
        *self.state_counter += 1;
        result
    }
}

impl<TS: Strategy + 'static> Default for GenericServiceCollection<TS> {
    fn default() -> Self {
        Self::new()
    }
}

impl<TS: Strategy + 'static> GenericServiceCollection<TS> {
    /// Creates an empty ServiceCollection
    pub fn new() -> Self {
        Self {
            strategy: PhantomData,
            producer_factories: RVec::new(),
        }
    }

    /// Generate a ServiceBuilder with `T` as a dependency.
    /// An instance of T is provided as an argument to the factory fn:
    /// ``` rust
    /// use {minfac::{AllRegistered, Registered, ServiceCollection, ServiceIterator, WeakServiceProvider}};
    ///
    /// let mut collection = ServiceCollection::new();
    ///
    /// // No dependency
    /// collection.register(|| 42u8);
    /// // Single Dependency
    /// collection.with::<Registered<u8>>().register(|i: u8| i as u16);
    /// // All of a type
    /// collection.with::<AllRegistered<u8>>().register(|i: ServiceIterator<u8>| i.map(|i| i as u32).sum::<u32>());
    /// // Multiple (max tupple size == 4)
    /// collection.with::<(Registered<u8>, Registered<u16>)>().register(|(byte, short)| (byte as u64));
    /// // Nested tuples for more than 4 Dependencies
    /// collection.with::<((Registered<u8>, Registered<u16>), (Registered<u32>, Registered<u64>))>()
    ///     .register(|((byte, short), (integer, long))| (byte as u128 + short as u128 + integer as u128 + long as u128));
    /// collection.with::<WeakServiceProvider>().register(|s: WeakServiceProvider| s.get::<u16>().expect("<i16> is available as optional parameter ") as u32);
    ///
    /// let provider = collection.build().expect("Dependencies are ok");
    /// assert_eq!(Some(42 * 4), provider.get::<u128>());
    /// ```
    pub fn with<T: Resolvable<TS>>(&mut self) -> ServiceBuilder<'_, T, TS> {
        ServiceBuilder(self, PhantomData)
    }

    /// Register an instance to be resolvable
    /// If a ServiceProviderFactory is used, all ServicesProviders will clone from the same origin
    pub fn register_instance<T: Identifyable<TS::Id> + Clone + 'static + Send + Sync>(
        &mut self,
        instance: T,
    ) {
        extern "C" fn factory<
            T: Identifyable<TS::Id> + Clone + 'static + Send + Sync,
            TS: Strategy + 'static,
        >(
            outer_ctx: AutoFreePointer,
            _ctx: &mut UntypedFnFactoryContext<TS>,
        ) -> InternalBuildResult<TS> {
            extern "C" fn func<
                T: Identifyable<TS::Id> + Clone + 'static + Send + Sync,
                TS: Strategy + 'static,
            >(
                _: *const ServiceProvider<TS>,
                outer_ctx: *const AutoFreePointer,
            ) -> T {
                let outer_ctx = unsafe { &*outer_ctx as &AutoFreePointer };
                unsafe { &*(outer_ctx.get_pointer() as *const T) }.clone()
            }
            FfiOk(UntypedFn::create(func::<T, TS>, outer_ctx))
        }

        let factory = UntypedFnFactory::boxed(instance, factory::<T, TS>);
        self.producer_factories
            .push(ServiceProducer::<TS>::new::<T>(factory));
    }

    /// Registers a transient service. In contrast to `with::<Registered<T>>().register(|d| {...})`, the lambda
    /// specifies the dependencies, which might be handy if the factory-fn is defined somewhere else.
    ///
    /// ``` rust
    /// use {minfac::{AllRegistered,Registered, ServiceCollection, ServiceIterator, WeakServiceProvider}};
    ///
    /// let mut collection = ServiceCollection::new();
    /// collection.register_with(routine as fn(_) -> _);
    /// collection.register(|| 20u8);
    /// collection.register(|| 22u16);
    /// let provider = collection.build().unwrap();
    /// assert_eq!(Some(42u32), provider.get::<u32>());
    ///
    /// fn routine((Registered(byte), AllRegistered(shorts)): (Registered<u8>, AllRegistered<u16>)) -> u32 {
    ///     byte as u32 + shorts.map(|x| x as u32).sum::<u32>()
    /// }
    /// ```
    pub fn register_with<T: registrar::Registrar<TS>>(
        &mut self,
        registrar: T,
    ) -> AliasBuilder<'_, T::Item, TS> {
        registrar.register(self)
    }

    /// Registers a transient service without dependencies.
    /// To add dependencies, use `with` to generate a ServiceBuilder.
    pub fn register<T: Identifyable<TS::Id>>(
        &mut self,
        creator: fn() -> T,
    ) -> AliasBuilder<'_, T, TS> {
        self.register_with(creator)
    }

    /// Registers a shared service without dependencies.
    /// To add dependencies, use `with` to generate a ServiceBuilder.
    ///
    /// Shared services must have a reference count == 0 after dropping the ServiceProvider. If an Arc is
    /// cloned and thus kept alive, ServiceProvider::drop will panic to prevent service leaking in std.
    pub fn register_shared<T: Send + Sync + Identifyable<TS::Id> + FromArcAutoFreePointer>(
        &mut self,
        creator: fn() -> T,
    ) -> AliasBuilder<'_, T, TS> {
        type InnerContext = (usize, AnyPtr);
        extern "C" fn factory<
            T: Send + Sync + FromArcAutoFreePointer + Identifyable<TS::Id>,
            TS: Strategy + 'static,
        >(
            outer_ctx: AutoFreePointer, // No-Alloc
            ctx: &mut UntypedFnFactoryContext<TS>,
        ) -> InternalBuildResult<TS> {
            extern "C" fn func<
                T: Send + Sync + 'static + FromArcAutoFreePointer + Identifyable<TS::Id>,
                TS: Strategy + 'static,
            >(
                provider: *const ServiceProvider<TS>,
                outer_ctx: *const AutoFreePointer,
            ) -> T {
                let provider = unsafe { &*provider as &ServiceProvider<TS> };
                let outer_ctx = unsafe { &*outer_ctx as &AutoFreePointer };
                let (service_state_idx, fnptr) =
                    unsafe { &*(outer_ctx.get_pointer() as *const InnerContext) };
                let creator: fn() -> T = unsafe { core::mem::transmute(*fnptr) };
                provider.get_or_initialize_pos(*service_state_idx, creator)
            }
            let service_state_idx = ctx.reserve_state_space();
            let inner: InnerContext = (service_state_idx, outer_ctx.get_pointer());
            FfiOk(UntypedFn::create(
                func::<T, TS>,
                AutoFreePointer::boxed(inner),
            ))
        }

        let factory = UntypedFnFactory::no_alloc(creator as AnyPtr, factory::<T, TS>);
        self.producer_factories
            .push(ServiceProducer::<TS>::new::<T>(factory));

        AliasBuilder::new(self)
    }

    /// Checks, if all dependencies of registered services are available.
    /// If no errors occured, Ok(ServiceProvider) is returned.
    pub fn build(self) -> Result<ServiceProvider<TS>, BuildError<TS>> {
        let validation = self.validate_producers(Vec::new())?;
        let shared_services = (0..validation.service_states_count)
            .map(|_| OnceLock::default())
            .collect();
        let immutable_state = service_provider::ServiceProviderImmutableState::new(
            validation.types,
            validation.producers,
            RVec::new(),
        );
        Ok(ServiceProvider::<TS>::new(
            RArc::new(immutable_state),
            shared_services,
            None,
        ))
    }

    ///
    /// Returns a factory which can efficiently create ServiceProviders from
    /// ServiceCollections which are missing one dependent service T (e.g. HttpRequest, StartupConfiguration)
    /// The missing service must implement `Any` + `Clone`.
    ///
    /// Unlike shared services, this service's reference counter isn't checked to equal zero when the provider is dropped
    ///
    pub fn build_factory<T: Clone + Identifyable<TS::Id> + Send + Sync>(
        self,
    ) -> Result<ServiceProviderFactory<T, TS>, BuildError<TS>> {
        ServiceProviderFactory::<_, TS>::create(self, RVec::new())
    }

    pub fn with_parent(
        self,
        provider: impl Into<WeakServiceProvider<TS>>,
    ) -> ServiceProviderFactoryBuilder<TS> {
        ServiceProviderFactoryBuilder::create(self, provider.into())
    }

    fn validate_producers(
        self,
        mut factories: Vec<ServiceProducer<TS>>,
    ) -> Result<ProducerValidationResult<TS>, BuildError<TS>> {
        let mut service_states_count: usize = 0;
        factories.extend(self.producer_factories);

        factories.sort_by_key(|a| a.identifier);

        let types: RVec<_> = factories.iter().map(|f| f.identifier).collect();

        let mut cyclic_reference_candidates = CycleChecker::default();
        let producers = factories
            .into_iter()
            .enumerate()
            .map(|(i, x)| {
                let mut ctx = UntypedFnFactoryContext {
                    state_counter: &mut service_states_count,
                    final_ordered_types: &types,
                    cyclic_reference_candidates: cyclic_reference_candidates.create_inserter(i),
                };

                match x.factory.call(&mut ctx) {
                    FfiOk(producer) => {
                        debug_assert_eq!(&x.identifier, producer.get_result_type_id());
                        Ok(producer)
                    }
                    FfiErr(e) => Err(e.into_build_error()),
                }
            })
            .collect::<Result<_, _>>()?;

        cyclic_reference_candidates
            .ok()
            .map_err(|description| BuildError::CyclicDependency { description })?;

        Ok(ProducerValidationResult {
            producers,
            types,
            service_states_count,
        })
    }
}

pub(crate) struct ProducerValidationResult<TS: Strategy + 'static> {
    producers: RVec<UntypedFn<TS>>,
    types: RVec<TS::Id>,
    service_states_count: usize,
}

/// Possible errors when calling ServiceCollection::build() or ServiceCollection::build_factory().
#[non_exhaustive]
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum BuildError<TS: Strategy> {
    /// `name`-format is subject of change and should only be used for debugging purpose
    #[non_exhaustive]
    MissingDependency {
        id: TS::Id,
        name: &'static str,
        dependee_name: &'static str,
    },
    /// `description`-format is subject of change and should only be used for debugging purpose
    #[non_exhaustive]
    CyclicDependency { description: String },
}

impl<TS: Strategy + Debug> core::fmt::Display for BuildError<TS> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            BuildError::MissingDependency {
                id,
                name,
                dependee_name,
            } => f.write_fmt(format_args!(
                "{dependee_name} is missing dependency {name} ({id:?})"
            )),
            BuildError::CyclicDependency { description } => {
                f.write_fmt(format_args!("detected cyclic dependency: {description}"))
            }
        }
    }
}

impl<TS: Strategy + Debug> core::error::Error for BuildError<TS> {}

#[derive(Debug)]
#[repr(C)]
pub struct MissingDependencyWithDependee<TS: Strategy> {
    id: <TS as Strategy>::Id,
    name: FfiStr<'static>,
    dependee_name: FfiStr<'static>,
}

impl<TS: Strategy + 'static> MissingDependencyWithDependee<TS> {
    fn into_build_error(self) -> BuildError<TS> {
        BuildError::MissingDependency {
            id: self.id,
            name: self.name.into(),
            dependee_name: self.dependee_name.into(),
        }
    }
}

#[derive(Debug)]
#[repr(C)]
pub struct MissingDependency<TS: Strategy> {
    id: <TS as Strategy>::Id,
    name: FfiStr<'static>,
}

impl<TS: Strategy + 'static> MissingDependency<TS> {
    fn new_missing_dependency<T: Identifyable<TS::Id>>() -> Self {
        MissingDependency {
            name: FfiStr::from(type_name::<T>()),
            id: T::get_id(),
        }
    }

    fn with_dependee<TDependee: core::any::Any>(self) -> MissingDependencyWithDependee<TS> {
        MissingDependencyWithDependee {
            id: self.id,
            name: self.name.into(),
            dependee_name: core::any::type_name::<TDependee>().into(),
        }
    }
}

#[doc(hidden)]
pub struct ServiceBuilder<'col, T: Resolvable<TS>, TS: Strategy + 'static = AnyStrategy>(
    pub &'col mut GenericServiceCollection<TS>,
    PhantomData<T>,
);

impl<TDep: Resolvable<TS> + 'static, TS: Strategy + 'static> ServiceBuilder<'_, TDep, TS> {
    pub fn register<T: Identifyable<TS::Id>>(
        &mut self,
        creator: fn(TDep::ItemPreChecked) -> T,
    ) -> AliasBuilder<'_, T, TS> {
        type InnerContext<TDep, TS> = (<TDep as SealedResolvable<TS>>::PrecheckResult, AnyPtr);
        extern "C" fn factory<
            T: Identifyable<TS::Id>,
            TDep: Resolvable<TS> + 'static,
            TS: Strategy + 'static,
        >(
            outer_ctx: AutoFreePointer, // No-Alloc
            ctx: &mut UntypedFnFactoryContext<TS>,
        ) -> InternalBuildResult<TS> {
            let key = match TDep::precheck(ctx.final_ordered_types) {
                Ok(x) => x,
                Err(x) => return FfiErr(x.with_dependee::<T>()),
            };
            let data = TDep::iter_positions(ctx.final_ordered_types);
            ctx.cyclic_reference_candidates.insert(
                type_name::<TDep::ItemPreChecked>().into(),
                FfiUsizeIterator::from_iter(data),
            );
            extern "C" fn func<
                T: Identifyable<TS::Id>,
                TDep: Resolvable<TS> + 'static,
                TS: Strategy + 'static,
            >(
                provider: *const ServiceProvider<TS>,
                outer_ctx: *const AutoFreePointer,
            ) -> T {
                let provider = unsafe { &*provider as &ServiceProvider<TS> };
                let outer_ctx = unsafe { &*outer_ctx as &AutoFreePointer };
                let (key, c): &InnerContext<TDep, TS> =
                    unsafe { &*(outer_ctx.get_pointer() as *const InnerContext<TDep, TS>) };
                let creator: fn(TDep::ItemPreChecked) -> T = unsafe { core::mem::transmute(*c) };
                let arg = TDep::resolve_prechecked(provider, key);
                creator(arg)
            }
            let inner: InnerContext<TDep, TS> = (key, outer_ctx.get_pointer());
            FfiOk(UntypedFn::create(
                func::<T, TDep, TS>,
                AutoFreePointer::boxed(inner),
            ))
        }
        let factory = UntypedFnFactory::no_alloc(creator as AnyPtr, factory::<T, TDep, TS>);
        self.0
            .producer_factories
            .push(ServiceProducer::<TS>::new::<T>(factory));

        AliasBuilder::new(self.0)
    }
    pub fn register_shared<T: Send + Sync + Identifyable<TS::Id> + FromArcAutoFreePointer>(
        &mut self,
        creator: fn(TDep::ItemPreChecked) -> T,
    ) -> AliasBuilder<'_, T, TS> {
        type InnerContext<TDep, TS> = (
            <TDep as SealedResolvable<TS>>::PrecheckResult,
            AnyPtr,
            usize,
        );
        extern "C" fn factory<
            T: Send + Sync + FromArcAutoFreePointer + Identifyable<TS::Id>,
            TDep: Resolvable<TS> + 'static,
            TS: Strategy + 'static,
        >(
            outer_ctx: AutoFreePointer,
            ctx: &mut UntypedFnFactoryContext<TS>,
        ) -> InternalBuildResult<TS> {
            let service_state_idx = ctx.reserve_state_space();
            let key = match TDep::precheck(ctx.final_ordered_types) {
                Ok(x) => x,
                Err(x) => return FfiErr(x.with_dependee::<T>()),
            };
            let data = TDep::iter_positions(ctx.final_ordered_types);
            ctx.cyclic_reference_candidates.insert(
                type_name::<TDep::ItemPreChecked>().into(),
                FfiUsizeIterator::from_iter(data),
            );
            extern "C" fn func<
                T: Send + Sync + 'static + FromArcAutoFreePointer + Identifyable<TS::Id>,
                TDep: Resolvable<TS> + 'static,
                TS: Strategy + 'static,
            >(
                provider: *const ServiceProvider<TS>,
                outer_ctx: *const AutoFreePointer,
            ) -> T {
                let provider = unsafe { &*provider as &ServiceProvider<TS> };
                let outer_ctx = unsafe { &*outer_ctx as &AutoFreePointer };
                let (key, c, service_state_idx): &InnerContext<TDep, TS> =
                    unsafe { &*(outer_ctx.get_pointer() as *const InnerContext<TDep, TS>) };
                provider.get_or_initialize_pos(*service_state_idx, || {
                    let creator: fn(TDep::ItemPreChecked) -> T =
                        unsafe { core::mem::transmute(*c) };
                    creator(TDep::resolve_prechecked(provider, key))
                })
            }
            let inner: InnerContext<TDep, TS> = (key, outer_ctx.get_pointer(), service_state_idx);
            FfiOk(UntypedFn::create(
                func::<T, TDep, TS>,
                AutoFreePointer::boxed(inner),
            ))
        }
        let factory = UntypedFnFactory::no_alloc(creator as AnyPtr, factory::<T, TDep, TS>);
        self.0
            .producer_factories
            .push(ServiceProducer::<TS>::new::<T>(factory));

        AliasBuilder::new(self.0)
    }
}

// At the time of writing, core::any::type_name_of_val was behind a nightly feature flag
#[repr(C)]
struct TypeNamed<T> {
    inner: T,
    type_name: FfiStr<'static>,
}