lref 0.3.0

//! Model metadata types for describing entities, properties, and relationships.
//!
//! These types form the metadata layer of lref, analogous to EFCore's
//! `IEntityType`, `IProperty`, `INavigation`, etc.

use std::borrow::Cow;
use std::any::TypeId;

// ---------------------------------------------------------------------------
// PropertyMeta — describes a single column / property
// ---------------------------------------------------------------------------

/// Metadata describing a property (column) of an entity type.
/// Corresponds to EFCore's `IProperty`.
#[derive(Debug, Clone)]
pub struct PropertyMeta {
    /// The Rust field name.
    pub field_name: Cow<'static, str>,
    /// The database column name (may differ from field_name via #[column]).
    pub column_name: Cow<'static, str>,
    /// The Rust type identifier.
    pub type_id: TypeId,
    /// Human-readable type name for debugging.
    pub type_name: Cow<'static, str>,
    /// Whether this property is part of the primary key.
    pub is_primary_key: bool,
    /// Whether this property is auto-increment / identity.
    pub is_auto_increment: bool,
    /// Whether this property is required (NOT NULL).
    pub is_required: bool,
    /// Whether this property is a foreign key.
    pub is_foreign_key: bool,
    /// Whether this property is used for optimistic concurrency control.
    pub is_concurrency_token: bool,
    /// Maximum length for string columns (None = unbounded).
    pub max_length: Option<usize>,
    /// Whether this property has a unique index.
    pub is_unique: bool,
    /// Whether this property has a regular index.
    pub has_index: bool,
    /// Whether this property is excluded from mapping (NotMapped).
    pub is_not_mapped: bool,
}

/// Builder for configuring [`PropertyMeta`].
pub struct PropertyMetaBuilder {
    meta: PropertyMeta,
}

impl PropertyMetaBuilder {
    pub fn new(field_name: &'static str, type_id: TypeId, type_name: &'static str) -> Self {
        Self {
            meta: PropertyMeta {
                field_name: Cow::Borrowed(field_name),
                column_name: Cow::Borrowed(field_name),
                type_id,
                type_name: Cow::Borrowed(type_name),
                is_primary_key: false,
                is_auto_increment: false,
                is_required: false,
                is_foreign_key: false,
                is_concurrency_token: false,
                max_length: None,
                is_unique: false,
                has_index: false,
                is_not_mapped: false,
            },
        }
    }

    pub fn column_name(mut self, name: &'static str) -> Self {
        self.meta.column_name = Cow::Borrowed(name);
        self
    }

    pub fn is_primary_key(mut self, v: bool) -> Self {
        self.meta.is_primary_key = v;
        self
    }

    pub fn is_auto_increment(mut self, v: bool) -> Self {
        self.meta.is_auto_increment = v;
        self
    }

    pub fn is_required(mut self, v: bool) -> Self {
        self.meta.is_required = v;
        self
    }

    pub fn is_foreign_key(mut self, v: bool) -> Self {
        self.meta.is_foreign_key = v;
        self
    }

    pub fn is_concurrency_token(mut self, v: bool) -> Self {
        self.meta.is_concurrency_token = v;
        self
    }

    pub fn max_length(mut self, n: usize) -> Self {
        self.meta.max_length = Some(n);
        self
    }

    pub fn is_unique(mut self, v: bool) -> Self {
        self.meta.is_unique = v;
        self
    }

    pub fn has_index(mut self, v: bool) -> Self {
        self.meta.has_index = v;
        self
    }

    pub fn is_not_mapped(mut self, v: bool) -> Self {
        self.meta.is_not_mapped = v;
        self
    }

    pub fn build(self) -> PropertyMeta {
        self.meta
    }
}

// ---------------------------------------------------------------------------
// NavigationMeta — describes a navigation property (relationship)
// ---------------------------------------------------------------------------

/// Describes the type of navigation.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum NavigationKind {
    /// BelongsTo<T> — reference to a single related entity (FK on this side).
    BelongsTo,
    /// HasOne<T> — reference to a single related entity (FK on other side).
    HasOne,
    /// HasMany<T> — collection of related entities.
    HasMany,
}

/// Metadata describing a navigation property (relationship).
/// Corresponds to EFCore's `INavigation`.
#[derive(Debug, Clone)]
pub struct NavigationMeta {
    /// The Rust field name of this navigation property.
    pub field_name: Cow<'static, str>,
    /// The kind of navigation (BelongsTo, HasOne, HasMany).
    pub kind: NavigationKind,
    /// The related entity's TypeId.
    pub related_type_id: TypeId,
    /// The related entity's type name.
    pub related_type_name: Cow<'static, str>,
    /// The foreign key property name on the dependent entity.
    pub foreign_key_field: Option<Cow<'static, str>>,
    /// The inverse navigation field name on the related entity.
    pub inverse_navigation: Option<Cow<'static, str>>,
    /// For many-to-many: the join entity TypeId.
    pub through_type_id: Option<TypeId>,
}

// ---------------------------------------------------------------------------
// EntityTypeMeta — describes an entity type as a whole
// ---------------------------------------------------------------------------

/// Metadata describing an entity type.
/// Corresponds to EFCore's `IEntityType`.
#[derive(Debug, Clone)]
pub struct EntityTypeMeta {
    /// The Rust type identifier.
    pub type_id: TypeId,
    /// The Rust struct name.
    pub type_name: Cow<'static, str>,
    /// The database table name.
    pub table_name: Cow<'static, str>,
    /// Properties (columns) of this entity.
    pub properties: Vec<PropertyMeta>,
    /// Navigation properties (relationships) of this entity.
    pub navigations: Vec<NavigationMeta>,
    /// The name of the primary key property (simplified; multi-key via Vec<String> in practice).
    pub primary_keys: Vec<Cow<'static, str>>,
}

impl EntityTypeMeta {
    /// Find a property by field name.
    pub fn find_property(&self, field_name: &str) -> Option<&PropertyMeta> {
        self.properties.iter().find(|p| p.field_name == field_name)
    }

    /// Find a navigation by field name.
    pub fn find_navigation(&self, field_name: &str) -> Option<&NavigationMeta> {
        self.navigations.iter().find(|n| n.field_name == field_name)
    }

    /// Get the primary key property.
    pub fn primary_key_property(&self) -> Option<&PropertyMeta> {
        self.properties.iter().find(|p| p.is_primary_key)
    }

    /// Returns properties that are not navigation and not mapped.
    pub fn mapped_scalar_properties(&self) -> impl Iterator<Item = &PropertyMeta> {
        self.properties.iter().filter(|p| !p.is_not_mapped)
    }
}