//! Functionality related to registering definitions of components. [ComponentInstanceProvider]s
//! should create [Component] instances based on those definitions, which can be registered
//! automatically or manually.

pub mod conditional;

use crate::component::{Component, ComponentDowncast, Injectable};
use crate::component_registry::conditional::{
    ComponentDefinitionRegistryFacade, ConditionMetadata, ContextFactory,
};
use crate::component_registry::internal::{
    ComponentAliasDefinition, ComponentAliasRegisterer, ComponentDefinitionRegisterer,
    TypedComponentDefinition,
};
use crate::component_registry::registry::NamedComponentDefinitionMap;
use crate::instance_provider::{
    CastFunction, ComponentInstanceAnyPtr, ComponentInstanceProvider,
    ComponentInstanceProviderError,
};
use derivative::Derivative;
#[cfg(feature = "async")]
use futures::future::BoxFuture;
use fxhash::{FxHashMap, FxHashSet};
use itertools::Itertools;
#[cfg(test)]
use mockall::automock;
use std::any::{type_name, TypeId};
use thiserror::Error;

#[cfg(not(feature = "async"))]
pub type Constructor = fn(
    instance_provider: &mut dyn ComponentInstanceProvider,
) -> Result<ComponentInstanceAnyPtr, ComponentInstanceProviderError>;
#[cfg(feature = "async")]
pub type Constructor =
    fn(
        instance_provider: &mut (dyn ComponentInstanceProvider + Sync + Send),
    ) -> BoxFuture<'_, Result<ComponentInstanceAnyPtr, ComponentInstanceProviderError>>;

/// Error related to component registries.
#[derive(Error, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug)]
pub enum ComponentDefinitionRegistryError {
    #[error("Attempted to register a duplicated component with name: {0}")]
    DuplicateComponentName(String),
    #[error("Attempted to re-register a concrete component type: {0}")]
    DuplicateComponentType(String),
    #[error("Missing base component of type {target_type} for alias: {alias_type}")]
    MissingBaseComponent {
        alias_type: String,
        target_type: String,
    },
    #[error(
        "Registering a duplicate primary component of type {target_type} for alias: {alias_type}"
    )]
    DuplicatePrimaryComponent {
        alias_type: String,
        target_type: String,
    },
}

/// Definition for a [Component] registered in a definition registry.
#[derive(Derivative, Clone)]
#[derivative(Debug)]
pub struct ComponentDefinition {
    /// Each component has at least one name, which can be used to request a specific instance.
    /// Derive-based components have their name generated from type name by converting it to snake
    /// case.
    pub names: FxHashSet<String>,

    /// With multiple components registered for a given type, one of them can be marked as primary
    /// and returned when requesting a single instance.
    pub is_primary: bool,

    /// Which type of [Scope](crate::scope::Scope) to use when requesting given component. Please
    /// see [scope](crate::scope) for details on scopes.
    pub scope: String,

    /// Concrete component type id. Since aliases can share definitions with their targets, there
    /// can be a need to find out what is the leaf type.
    pub resolved_type_id: TypeId,

    /// Constructor method for type-erased instances.
    #[derivative(Debug = "ignore")]
    pub constructor: Constructor,

    /// Cast function associated for given type. Please see the documentation for [CastFunction] for
    /// details on usage.
    #[derivative(Debug = "ignore")]
    pub cast: CastFunction,
}

/// Registration information for a [Component]. Please see [ComponentDefinition] for information
/// about the meaning of the fields.
#[derive(Derivative, Clone)]
#[derivative(Debug)]
pub struct ComponentMetadata {
    pub names: FxHashSet<String>,

    pub scope: String,

    #[derivative(Debug = "ignore")]
    pub constructor: Constructor,

    #[derivative(Debug = "ignore")]
    pub cast: CastFunction,
}

/// Registration information for an  alias for a [Component] registered in a definition registry.
/// Please see [ComponentDefinition] for information about the meaning of the fields.
#[derive(Clone, Derivative)]
#[derivative(Debug)]
pub struct ComponentAliasMetadata {
    pub is_primary: bool,

    pub scope: Option<String>,

    #[derivative(Debug = "ignore")]
    pub cast: CastFunction,
}

/// A registry of component definitions which can be used when requesting instances via a
/// [ComponentInstanceProvider].
#[cfg_attr(test, automock)]
pub trait ComponentDefinitionRegistry {
    /// Adds a new definition for a given type. Note: handling of duplicate component names is
    /// registry-dependent. Name is used for reporting purposes.
    fn register_component(
        &mut self,
        target: TypeId,
        target_name: &str,
        metadata: &ComponentMetadata,
    ) -> Result<(), ComponentDefinitionRegistryError>;

    /// Adds an alias for a component of target type. This is useful when registering
    /// `dyn Trait` as an alias for a given concrete type. If alias cannot by cast to target,
    /// component creation will fail. Names are used for reporting purposes.
    fn register_alias(
        &mut self,
        alias_type: TypeId,
        target_type: TypeId,
        alias_name: &str,
        target_name: &str,
        metadata: &ComponentAliasMetadata,
    ) -> Result<(), ComponentDefinitionRegistryError>;

    /// Returns all registered definitions for a given type.
    fn components_by_type(&self, type_id: TypeId) -> Vec<ComponentDefinition>;

    /// Returns a definition with given name.
    fn component_by_name(&self, name: &str, type_id: TypeId) -> Option<ComponentDefinition>;

    /// Returns primary component for a given type.
    fn primary_component(&self, type_id: TypeId) -> Option<ComponentDefinition>;

    /// Checks if given type is present in this registry.
    fn is_registered(&self, type_id: TypeId) -> bool;

    /// Checks if there's a definition with given name.
    fn is_name_registered(&self, name: &str) -> bool;

    /// Returns a copy of the whole registry as a map.
    fn all_definitions(&self) -> FxHashMap<TypeId, Vec<ComponentDefinition>>;
}

/// Helper trait for [ComponentDefinitionRegistry] providing strongly-typed access.
pub trait TypedComponentDefinitionRegistry {
    /// Typesafe version of [ComponentDefinitionRegistry::register_component].
    fn register_component_typed<T: Component>(
        &mut self,
        metadata: &ComponentMetadata,
    ) -> Result<(), ComponentDefinitionRegistryError>;

    /// Typesafe version of [ComponentDefinitionRegistry::register_alias].
    fn register_alias_typed<Source: ComponentDowncast<Target> + ?Sized, Target: Component>(
        &mut self,
        metadata: &ComponentAliasMetadata,
    ) -> Result<(), ComponentDefinitionRegistryError>;

    /// Typesafe version of [ComponentDefinitionRegistry::components_by_type].
    fn components_by_type_typed<T: Injectable + ?Sized>(&self) -> Vec<ComponentDefinition>;

    /// Typesafe version of [ComponentDefinitionRegistry::primary_component].
    fn primary_component_typed<T: Injectable + ?Sized>(&self) -> Option<ComponentDefinition>;

    /// Typesafe version of [ComponentDefinitionRegistry::is_registered].
    fn is_registered_typed<T: Injectable>(&self) -> bool;
}

impl<CDR: ComponentDefinitionRegistry + ?Sized> TypedComponentDefinitionRegistry for CDR {
    #[inline]
    fn register_component_typed<T: Component>(
        &mut self,
        metadata: &ComponentMetadata,
    ) -> Result<(), ComponentDefinitionRegistryError> {
        self.register_component(TypeId::of::<T>(), type_name::<T>(), metadata)
    }

    #[inline]
    fn register_alias_typed<Source: ComponentDowncast<Target> + ?Sized, Target: Component>(
        &mut self,
        metadata: &ComponentAliasMetadata,
    ) -> Result<(), ComponentDefinitionRegistryError> {
        self.register_alias(
            TypeId::of::<Source>(),
            TypeId::of::<Target>(),
            type_name::<Source>(),
            type_name::<Target>(),
            metadata,
        )
    }

    #[inline]
    fn components_by_type_typed<T: Injectable + ?Sized>(&self) -> Vec<ComponentDefinition> {
        self.components_by_type(TypeId::of::<T>())
    }

    #[inline]
    fn primary_component_typed<T: Injectable + ?Sized>(&self) -> Option<ComponentDefinition> {
        self.primary_component(TypeId::of::<T>())
    }

    #[inline]
    fn is_registered_typed<T: Injectable>(&self) -> bool {
        self.is_registered(TypeId::of::<T>())
    }
}

/// Registry of component definitions initialized from statically registered definitions.
#[derive(Clone, Debug)]
pub struct StaticComponentDefinitionRegistry {
    definition_map: NamedComponentDefinitionMap,
    allow_definition_overriding: bool,
}

impl StaticComponentDefinitionRegistry {
    pub fn new<CF: ContextFactory>(
        allow_definition_overriding: bool,
        context_factory: &CF,
    ) -> Result<Self, ComponentDefinitionRegistryError> {
        let component_definitions: Vec<TypedComponentDefinition> =
            inventory::iter::<ComponentDefinitionRegisterer>
                .into_iter()
                .map(|registerer| (registerer.register)())
                .collect_vec();

        let alias_definitions: Vec<ComponentAliasDefinition> =
            inventory::iter::<ComponentAliasRegisterer>
                .into_iter()
                .map(|registerer| (registerer.register)())
                .collect_vec();

        // components need to be registered in appropriate order to ensure dependencies are met:
        // 1. unconditional components - they depend on nothing, so can go first
        // 2. unconditional aliases for unconditional components - they only depend on the above
        // 3. conditional components - they might depend on the above or each other
        // 4. unconditional aliases for conditional components - they might depend on the above only
        // 5. conditional aliases - they might depend on anything

        let (definition_map, enabled_types) = Self::register_unconditional_components(
            &component_definitions,
            allow_definition_overriding,
        )?;

        let mut registry = Self {
            definition_map,
            allow_definition_overriding,
        };

        // register aliases for unconditionally registered components
        registry.register_unconditional_aliases(&alias_definitions, &enabled_types)?;

        registry.register_conditional_components_with_dependents(
            component_definitions,
            alias_definitions.clone(),
            enabled_types,
            context_factory,
        )?;

        Ok(registry)
    }

    fn register_conditional_components_with_dependents<CF: ContextFactory>(
        &mut self,
        component_definitions: Vec<TypedComponentDefinition>,
        alias_definitions: Vec<ComponentAliasDefinition>,
        mut enabled_types: FxHashSet<TypeId>,
        context_factory: &CF,
    ) -> Result<(), ComponentDefinitionRegistryError> {
        if component_definitions.is_empty() && alias_definitions.is_empty() {
            return Ok(());
        }

        let mut new_enabled_types = FxHashSet::default();

        for (definition, condition) in component_definitions
            .iter()
            .filter_map(|definition| {
                definition
                    .condition
                    .map(|condition| (definition, condition))
            })
            .sorted_by_key(|(definition, _)| -definition.priority)
        {
            if (condition)(
                context_factory.create_context(self).as_ref(),
                ConditionMetadata::Component {
                    type_id: definition.target,
                    metadata: &definition.metadata,
                },
            ) {
                self.definition_map.try_register_component(
                    definition.target,
                    definition.target_name,
                    &definition.metadata,
                    self.allow_definition_overriding,
                )?;

                new_enabled_types.insert(definition.target);
            }
        }

        self.register_unconditional_aliases(&alias_definitions, &new_enabled_types)?;

        enabled_types.extend(new_enabled_types.into_iter());

        for (definition, condition) in alias_definitions
            .iter()
            .filter(|definition| enabled_types.contains(&definition.target_type))
            .filter_map(|definition| {
                definition
                    .condition
                    .map(|condition| (definition, condition))
            })
            .sorted_by_key(|(definition, _)| -definition.priority)
        {
            if (condition)(
                context_factory.create_context(self).as_ref(),
                ConditionMetadata::Alias {
                    alias_type: definition.alias_type,
                    target_type: definition.target_type,
                    metadata: &definition.metadata,
                },
            ) {
                self.definition_map.try_register_alias(
                    definition.alias_type,
                    definition.target_type,
                    definition.alias_name,
                    definition.target_name,
                    &definition.metadata,
                )?;
            }
        }

        Ok(())
    }

    fn register_unconditional_components(
        component_definitions: &[TypedComponentDefinition],
        allow_definition_overriding: bool,
    ) -> Result<(NamedComponentDefinitionMap, FxHashSet<TypeId>), ComponentDefinitionRegistryError>
    {
        let mut definition_map = NamedComponentDefinitionMap::default();
        let mut enabled_types = FxHashSet::default();

        for definition in component_definitions
            .iter()
            .filter(|definition| definition.condition.is_none())
        {
            definition_map.try_register_component(
                definition.target,
                definition.target_name,
                &definition.metadata,
                allow_definition_overriding,
            )?;

            enabled_types.insert(definition.target);
        }

        Ok((definition_map, enabled_types))
    }

    fn register_unconditional_aliases(
        &mut self,
        alias_definitions: &[ComponentAliasDefinition],
        enabled_types: &FxHashSet<TypeId>,
    ) -> Result<(), ComponentDefinitionRegistryError> {
        for definition in alias_definitions.iter().filter(|definition| {
            definition.condition.is_none() && enabled_types.contains(&definition.target_type)
        }) {
            self.definition_map.try_register_alias(
                definition.alias_type,
                definition.target_type,
                definition.alias_name,
                definition.target_name,
                &definition.metadata,
            )?;
        }

        Ok(())
    }
}

impl ComponentDefinitionRegistry for StaticComponentDefinitionRegistry {
    #[inline]
    fn register_component(
        &mut self,
        target: TypeId,
        target_name: &str,
        metadata: &ComponentMetadata,
    ) -> Result<(), ComponentDefinitionRegistryError> {
        self.definition_map.try_register_component(
            target,
            target_name,
            metadata,
            self.allow_definition_overriding,
        )
    }

    #[inline]
    fn register_alias(
        &mut self,
        alias_type: TypeId,
        target_type: TypeId,
        alias_name: &str,
        target_name: &str,
        metadata: &ComponentAliasMetadata,
    ) -> Result<(), ComponentDefinitionRegistryError> {
        self.definition_map.try_register_alias(
            alias_type,
            target_type,
            alias_name,
            target_name,
            metadata,
        )
    }

    #[inline]
    fn components_by_type(&self, type_id: TypeId) -> Vec<ComponentDefinition> {
        self.definition_map.components_by_type(type_id)
    }

    #[inline]
    fn component_by_name(&self, name: &str, type_id: TypeId) -> Option<ComponentDefinition> {
        self.definition_map.component_by_name(name, type_id)
    }

    #[inline]
    fn primary_component(&self, type_id: TypeId) -> Option<ComponentDefinition> {
        self.definition_map.primary_component(type_id)
    }

    #[inline]
    fn is_registered(&self, type_id: TypeId) -> bool {
        <Self as ComponentDefinitionRegistryFacade>::is_registered(self, type_id)
    }

    #[inline]
    fn is_name_registered(&self, name: &str) -> bool {
        <Self as ComponentDefinitionRegistryFacade>::is_name_registered(self, name)
    }

    #[inline]
    fn all_definitions(&self) -> FxHashMap<TypeId, Vec<ComponentDefinition>> {
        self.definition_map.all_definitions()
    }
}

impl ComponentDefinitionRegistryFacade for StaticComponentDefinitionRegistry {
    #[inline]
    fn is_registered(&self, target: TypeId) -> bool {
        self.definition_map.is_registered(target)
    }

    #[inline]
    fn is_name_registered(&self, name: &str) -> bool {
        self.definition_map.is_name_registered(name)
    }
}

mod registry {
    use crate::component_registry::ComponentDefinitionRegistryError;
    use crate::component_registry::{
        ComponentAliasMetadata, ComponentDefinition, ComponentMetadata,
    };
    use fxhash::{FxHashMap, FxHashSet};
    use std::any::TypeId;

    #[derive(Default, Clone, Debug)]
    pub(super) struct NamedComponentDefinitionMap {
        definitions: FxHashMap<TypeId, Vec<ComponentDefinition>>,
        names: FxHashSet<String>,
    }

    impl NamedComponentDefinitionMap {
        pub(super) fn component_by_name(
            &self,
            name: &str,
            type_id: TypeId,
        ) -> Option<ComponentDefinition> {
            self.definitions
                .get(&type_id)
                .and_then(|definitions| {
                    definitions
                        .iter()
                        .find(|definition| definition.names.contains(name))
                })
                .cloned()
        }

        pub(super) fn components_by_type(&self, type_id: TypeId) -> Vec<ComponentDefinition> {
            self.definitions.get(&type_id).cloned().unwrap_or_default()
        }

        pub(super) fn primary_component(&self, type_id: TypeId) -> Option<ComponentDefinition> {
            self.definitions.get(&type_id).and_then(|definitions| {
                (if definitions.len() == 1 {
                    definitions.get(0)
                } else {
                    definitions.iter().find(|definition| definition.is_primary)
                })
                .cloned()
            })
        }

        pub(super) fn try_register_alias(
            &mut self,
            alias_type: TypeId,
            target_type: TypeId,
            alias_name: &str,
            target_name: &str,
            metadata: &ComponentAliasMetadata,
        ) -> Result<(), ComponentDefinitionRegistryError> {
            let mut target_definitions = self
                .definitions
                .get(&target_type)
                .ok_or(ComponentDefinitionRegistryError::MissingBaseComponent {
                    alias_type: alias_name.to_string(),
                    target_type: target_name.to_string(),
                })
                .cloned()?;

            // this should not be possible, since we don't allow removing definitions, but better
            // be safe
            if target_definitions.is_empty() {
                return Err(ComponentDefinitionRegistryError::MissingBaseComponent {
                    alias_type: alias_name.to_string(),
                    target_type: target_name.to_string(),
                });
            }

            // if we're registering a primary alias, there needs to be a single target
            if metadata.is_primary && target_definitions.len() > 1 {
                return Err(
                    ComponentDefinitionRegistryError::DuplicatePrimaryComponent {
                        alias_type: alias_name.to_string(),
                        target_type: target_name.to_string(),
                    },
                );
            }

            // should run once due to above anyway
            for definition in &mut target_definitions {
                definition.is_primary = metadata.is_primary;
                definition.cast = metadata.cast;

                if let Some(scope) = &metadata.scope {
                    definition.scope = scope.clone();
                }
            }

            if let Some(alias_definitions) = self.definitions.get_mut(&alias_type) {
                if metadata.is_primary
                    && alias_definitions
                        .iter()
                        .any(|definition| definition.is_primary)
                {
                    return Err(
                        ComponentDefinitionRegistryError::DuplicatePrimaryComponent {
                            alias_type: alias_name.to_string(),
                            target_type: target_name.to_string(),
                        },
                    );
                }

                alias_definitions.append(&mut target_definitions);
            } else {
                self.definitions.insert(alias_type, target_definitions);
            }

            Ok(())
        }

        pub(super) fn try_register_component(
            &mut self,
            target: TypeId,
            target_name: &str,
            metadata: &ComponentMetadata,
            allow_definition_overriding: bool,
        ) -> Result<(), ComponentDefinitionRegistryError> {
            if !allow_definition_overriding {
                if let Some(name) = metadata.names.iter().find_map(|name| {
                    if self.names.contains(name) {
                        Some(name.clone())
                    } else {
                        None
                    }
                }) {
                    return Err(ComponentDefinitionRegistryError::DuplicateComponentName(
                        name,
                    ));
                }
            }

            let definition = ComponentDefinition {
                names: metadata.names.clone(),
                is_primary: false,
                scope: metadata.scope.clone(),
                resolved_type_id: target,
                constructor: metadata.constructor,
                cast: metadata.cast,
            };

            let names = definition.names.clone();

            if let Some(entries) = self.definitions.get_mut(&target) {
                // concrete component types should not have multiple definitions
                debug_assert!(entries.len() <= 1);

                if !allow_definition_overriding && !entries.is_empty() {
                    return Err(ComponentDefinitionRegistryError::DuplicateComponentType(
                        target_name.to_string(),
                    ));
                }

                entries
                    .iter()
                    .flat_map(|entry| entry.names.iter())
                    .for_each(|name| {
                        self.names.remove(name);
                    });

                *entries = vec![definition];
            } else {
                self.definitions.insert(target, vec![definition]);
            }

            self.names.extend(names.into_iter());
            Ok(())
        }

        #[inline]
        pub(super) fn is_registered(&self, target: TypeId) -> bool {
            self.definitions
                .get(&target)
                .map(|definitions| !definitions.is_empty())
                .unwrap_or(false)
        }

        #[inline]
        pub(super) fn is_name_registered(&self, name: &str) -> bool {
            self.names.contains(name)
        }

        #[inline]
        pub(super) fn all_definitions(&self) -> FxHashMap<TypeId, Vec<ComponentDefinition>> {
            self.definitions.clone()
        }
    }

    #[cfg(test)]
    mod tests {
        #[cfg(not(feature = "async"))]
        mod sync {
            use crate::component_registry::registry::NamedComponentDefinitionMap;
            use crate::component_registry::{
                ComponentAliasMetadata, ComponentDefinitionRegistryError, ComponentMetadata,
            };
            use crate::instance_provider::{
                ComponentInstanceAnyPtr, ComponentInstanceProvider, ComponentInstanceProviderError,
                ComponentInstancePtr,
            };
            use std::any::{Any, TypeId};

            fn cast(
                instance: ComponentInstanceAnyPtr,
            ) -> Result<Box<dyn Any>, ComponentInstanceAnyPtr> {
                Err(instance)
            }

            fn constructor(
                _instance_provider: &mut dyn ComponentInstanceProvider,
            ) -> Result<ComponentInstanceAnyPtr, ComponentInstanceProviderError> {
                Ok(ComponentInstancePtr::new(0) as ComponentInstanceAnyPtr)
            }

            fn create_metadata() -> (ComponentMetadata, TypeId) {
                (
                    ComponentMetadata {
                        names: ["name".to_string()].into_iter().collect(),
                        scope: "".to_string(),
                        constructor,
                        cast,
                    },
                    TypeId::of::<i8>(),
                )
            }

            #[test]
            fn should_reject_primary_alias_for_ambiguous_target() {
                let definition = ComponentMetadata {
                    names: Default::default(),
                    scope: "".to_string(),
                    constructor,
                    cast,
                };
                let alias_id_1 = TypeId::of::<u8>();
                let alias_id_2 = TypeId::of::<u16>();
                let target_id_1 = TypeId::of::<i16>();
                let target_id_2 = TypeId::of::<u16>();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(target_id_1, "", &definition, false)
                    .unwrap();
                registry
                    .try_register_component(target_id_2, "", &definition, false)
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id_1,
                        target_id_1,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: false,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id_1,
                        target_id_2,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: false,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();

                assert!(matches!(
                    registry
                        .try_register_alias(
                            alias_id_2,
                            alias_id_1,
                            "",
                            "",
                            &ComponentAliasMetadata {
                                is_primary: true,
                                scope: None,
                                cast,
                            },
                        )
                        .unwrap_err(),
                    ComponentDefinitionRegistryError::DuplicatePrimaryComponent { .. }
                ));
            }

            #[test]
            fn should_register_definition() {
                let (definition, id) = create_metadata();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id, "", &definition, false)
                    .unwrap();

                assert_eq!(registry.components_by_type(id)[0].names, definition.names);
                assert_eq!(
                    registry.component_by_name("name", id).unwrap().names,
                    definition.names
                );
                assert!(registry.is_registered(id));
                assert!(registry.is_name_registered("name"));
            }

            #[test]
            fn should_not_register_duplicate_name() {
                let (definition, id) = create_metadata();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id, "", &definition, false)
                    .unwrap();

                assert!(matches!(
                    registry
                        .try_register_component(id, "", &definition, false)
                        .unwrap_err(),
                    ComponentDefinitionRegistryError::DuplicateComponentName(..)
                ));
            }

            #[test]
            fn should_override_duplicate_name() {
                let (definition, id) = create_metadata();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id, "", &definition, true)
                    .unwrap();
                registry
                    .try_register_component(id, "", &definition, true)
                    .unwrap();
            }

            #[test]
            fn should_register_alias() {
                let (definition, id) = create_metadata();
                let alias_id = TypeId::of::<u8>();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id, "", &definition, false)
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id,
                        id,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: false,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();

                assert_eq!(
                    registry.components_by_type(alias_id)[0].names,
                    definition.names
                );
            }

            #[test]
            fn should_register_alias_scope() {
                let (definition, id) = create_metadata();
                let alias_id = TypeId::of::<u8>();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id, "", &definition, false)
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id,
                        id,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: false,
                            scope: Some("scope".to_string()),
                            cast,
                        },
                    )
                    .unwrap();

                assert_eq!(registry.components_by_type(alias_id)[0].scope, "scope");
            }

            #[test]
            fn should_reject_duplicate_primary_alias() {
                let (definition, id) = create_metadata();
                let alias_id = TypeId::of::<u8>();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id, "", &definition, false)
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id,
                        id,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: true,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();

                assert!(matches!(
                    registry
                        .try_register_alias(
                            alias_id,
                            id,
                            "",
                            "",
                            &ComponentAliasMetadata {
                                is_primary: true,
                                scope: None,
                                cast
                            },
                        )
                        .unwrap_err(),
                    ComponentDefinitionRegistryError::DuplicatePrimaryComponent { .. }
                ));
            }

            #[test]
            fn should_return_primary_single_definition() {
                let (definition, id) = create_metadata();
                let alias_id = TypeId::of::<u8>();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id, "", &definition, false)
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id,
                        id,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: false,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();

                assert!(registry.primary_component(alias_id).is_some());
            }

            #[test]
            fn should_return_explicit_primary_definition() {
                let (definition, id_1) = create_metadata();
                let id_2 = TypeId::of::<u16>();
                let alias_id = TypeId::of::<u8>();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id_1, "", &definition, false)
                    .unwrap();
                registry
                    .try_register_component(id_2, "", &definition, true)
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id,
                        id_1,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: false,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id,
                        id_2,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: true,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();

                assert!(registry.primary_component(alias_id).is_some());
            }

            #[test]
            fn should_not_return_unknown_primary_definition() {
                let (definition, id_1) = create_metadata();
                let id_2 = TypeId::of::<u16>();
                let alias_id = TypeId::of::<u8>();

                let mut registry = NamedComponentDefinitionMap::default();
                registry
                    .try_register_component(id_1, "", &definition, false)
                    .unwrap();
                registry
                    .try_register_component(id_2, "", &definition, true)
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id,
                        id_1,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: false,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();
                registry
                    .try_register_alias(
                        alias_id,
                        id_2,
                        "",
                        "",
                        &ComponentAliasMetadata {
                            is_primary: false,
                            scope: None,
                            cast,
                        },
                    )
                    .unwrap();

                assert!(registry.primary_component(alias_id).is_none());
            }
        }
    }
}

#[doc(hidden)]
pub mod internal {
    use crate::component_registry::conditional::ComponentCondition;
    use crate::component_registry::{ComponentAliasMetadata, ComponentMetadata};
    use inventory::collect;
    pub use inventory::submit;
    use std::any::TypeId;

    #[derive(Clone)]
    pub struct TypedComponentDefinition {
        pub target: TypeId,
        pub target_name: &'static str,
        pub condition: Option<ComponentCondition>,
        pub priority: i8,
        pub metadata: ComponentMetadata,
    }

    pub struct ComponentDefinitionRegisterer {
        pub register: fn() -> TypedComponentDefinition,
    }

    #[derive(Clone)]
    pub struct ComponentAliasDefinition {
        pub alias_type: TypeId,
        pub target_type: TypeId,
        pub alias_name: &'static str,
        pub target_name: &'static str,
        pub condition: Option<ComponentCondition>,
        pub priority: i8,
        pub metadata: ComponentAliasMetadata,
    }

    pub struct ComponentAliasRegisterer {
        pub register: fn() -> ComponentAliasDefinition,
    }

    collect!(ComponentDefinitionRegisterer);
    collect!(ComponentAliasRegisterer);
}

#[cfg(test)]
//noinspection DuplicatedCode
mod tests {
    #[cfg(not(feature = "async"))]
    mod sync {
        use crate::component::{Component, ComponentDowncast, Injectable};
        use crate::component_registry::conditional::{
            ComponentDefinitionRegistryFacade, SimpleContextFactory,
        };
        use crate::component_registry::ComponentDefinitionRegistryError;
        use crate::component_registry::{
            ComponentDefinition, ComponentDefinitionRegistry, ComponentMetadata,
            StaticComponentDefinitionRegistry, TypedComponentDefinitionRegistry,
        };
        use crate::instance_provider::{
            ComponentInstanceAnyPtr, ComponentInstanceProvider, ComponentInstanceProviderError,
            ComponentInstancePtr,
        };
        use std::any::{Any, TypeId};

        struct TestComponent;

        impl Injectable for TestComponent {}

        impl ComponentDowncast<TestComponent> for TestComponent {
            fn downcast(
                source: ComponentInstanceAnyPtr,
            ) -> Result<ComponentInstancePtr<Self>, ComponentInstanceAnyPtr> {
                source.downcast()
            }
        }

        impl Component for TestComponent {
            fn create(
                _instance_provider: &mut dyn ComponentInstanceProvider,
            ) -> Result<Self, ComponentInstanceProviderError>
            where
                Self: Sized,
            {
                Ok(TestComponent)
            }
        }

        fn test_constructor(
            instance_provider: &mut dyn ComponentInstanceProvider,
        ) -> Result<ComponentInstanceAnyPtr, ComponentInstanceProviderError> {
            TestComponent::create(instance_provider)
                .map(|p| ComponentInstancePtr::new(p) as ComponentInstanceAnyPtr)
        }

        fn test_cast(
            instance: ComponentInstanceAnyPtr,
        ) -> Result<Box<dyn Any>, ComponentInstanceAnyPtr> {
            TestComponent::downcast(instance).map(|p| Box::new(p) as Box<dyn Any>)
        }

        #[test]
        fn should_register_definition() {
            let mut registry =
                StaticComponentDefinitionRegistry::new(false, &SimpleContextFactory::default())
                    .unwrap();
            registry
                .register_component_typed::<TestComponent>(&ComponentMetadata {
                    names: ["a".to_string()].into_iter().collect(),
                    scope: "".to_string(),
                    constructor: test_constructor,
                    cast: test_cast,
                })
                .unwrap();

            assert!(!registry
                .components_by_type_typed::<TestComponent>()
                .is_empty());
            assert!(TypedComponentDefinitionRegistry::is_registered_typed::<
                TestComponent,
            >(&registry));
            assert!(ComponentDefinitionRegistryFacade::is_registered(
                &registry,
                TypeId::of::<TestComponent>(),
            ));
            assert!(ComponentDefinitionRegistry::is_name_registered(
                &registry, "a",
            ));
        }

        #[test]
        fn should_not_register_duplicate_name() {
            let definition = ComponentDefinition {
                names: ["name".to_string()].into_iter().collect(),
                is_primary: false,
                scope: "".to_string(),
                resolved_type_id: TypeId::of::<TestComponent>(),
                constructor: test_constructor,
                cast: test_cast,
            };

            let mut registry =
                StaticComponentDefinitionRegistry::new(false, &SimpleContextFactory::default())
                    .unwrap();
            registry
                .register_component_typed::<TestComponent>(&ComponentMetadata {
                    names: definition.names.clone(),
                    scope: "".to_string(),
                    constructor: test_constructor,
                    cast: test_cast,
                })
                .unwrap();

            assert_eq!(
                registry
                    .register_component_typed::<TestComponent>(&ComponentMetadata {
                        names: definition.names,
                        scope: "".to_string(),
                        constructor: test_constructor,
                        cast: test_cast,
                    })
                    .unwrap_err(),
                ComponentDefinitionRegistryError::DuplicateComponentName("name".to_string())
            );
        }

        #[test]
        fn should_override_duplicate_name() {
            let mut registry =
                StaticComponentDefinitionRegistry::new(true, &SimpleContextFactory::default())
                    .unwrap();
            registry
                .register_component_typed::<TestComponent>(&ComponentMetadata {
                    names: ["name".to_string()].into_iter().collect(),
                    scope: "".to_string(),
                    constructor: test_constructor,
                    cast: test_cast,
                })
                .unwrap();
            registry
                .register_component_typed::<TestComponent>(&ComponentMetadata {
                    names: ["name2".to_string()].into_iter().collect(),
                    scope: "".to_string(),
                    constructor: test_constructor,
                    cast: test_cast,
                })
                .unwrap();

            registry
                .component_by_name("name2", TypeId::of::<TestComponent>())
                .unwrap();
        }
    }
}