ploidy_core/ir/views/

operation.rs

//! Operations: per-path methods with parameter, request, and response schemas.
//!
//! In OpenAPI, each path item defines operations for HTTP methods like
//! `GET` and `POST`. An operation has path and query parameters, an
//! optional request body, and an optional response body:
//!
//! ```yaml
//! paths:
//!   /pets/{pet_id}:
//!     post:
//!       operationId: updatePet
//!       parameters:
//!         - name: pet_id
//!           in: path
//!           required: true
//!           schema:
//!             type: string
//!         - name: expand
//!           in: query
//!           schema:
//!             type: boolean
//!       requestBody:
//!         content:
//!           application/json:
//!             schema:
//!               $ref: '#/components/schemas/PetUpdate'
//!       responses:
//!         '200':
//!           content:
//!             application/json:
//!               schema:
//!                 $ref: '#/components/schemas/Pet'
//! ```
//!
//! Ploidy represents this as an [`OperationView`] with:
//!
//! * An [ID], an [HTTP method], and a [path template] with
//!   segments and path parameters.
//! * [Query parameters], each with a name, type, and
//!   optional serialization style.
//! * An optional [request] and [response] body, each wrapping
//!   a [`TypeView`] of the body schema.
//! * An optional [resource name] from the `x-resource-name` extension,
//!   used to group operations by resource.
//!
//! Unlike types, operations are not nodes in Ploidy's dependency graph,
//! but they implement [`View`] for traversal.
//!
//! [ID]: OperationView::id
//! [HTTP method]: OperationView::method
//! [path template]: OperationView::path
//! [Query parameters]: OperationView::query
//! [request]: OperationView::request
//! [response]: OperationView::response
//! [resource name]: OperationView::resource

use std::{collections::VecDeque, marker::PhantomData};

use petgraph::{
    graph::NodeIndex,
    visit::{Bfs, EdgeFiltered, EdgeRef, Visitable},
};

use crate::{
    ir::{
        graph::CookedGraph,
        types::{
            GraphOperation, GraphParameter, GraphParameterInfo, GraphRequest, GraphResponse,
            GraphType, ParameterStyle,
        },
    },
    parse::{
        Method,
        path::{PathQueryParameter, PathSegment},
    },
};

use super::{View, inline::InlineTypeView, ir::TypeView};

/// A graph-aware view of an [operation][GraphOperation].
#[derive(Debug)]
pub struct OperationView<'graph, 'a> {
    cooked: &'graph CookedGraph<'a>,
    op: &'graph GraphOperation<'a>,
}

impl<'graph, 'a> OperationView<'graph, 'a> {
    #[inline]
    pub(in crate::ir) fn new(
        cooked: &'graph CookedGraph<'a>,
        op: &'graph GraphOperation<'a>,
    ) -> Self {
        Self { cooked, op }
    }

    /// Returns the `operationId`.
    #[inline]
    pub fn id(&self) -> &'a str {
        self.op.id
    }

    /// Returns the HTTP method.
    #[inline]
    pub fn method(&self) -> Method {
        self.op.method
    }

    /// Returns a view of this operation's path template.
    #[inline]
    pub fn path(&self) -> OperationViewPath<'_, 'graph, 'a> {
        OperationViewPath(self)
    }

    /// Returns the description, if present in the spec.
    #[inline]
    pub fn description(&self) -> Option<&'a str> {
        self.op.description
    }

    /// Returns an iterator over this operation's query parameters.
    #[inline]
    pub fn query(&self) -> impl Iterator<Item = ParameterView<'_, 'graph, 'a, QueryParameter>> {
        self.op.params.iter().filter_map(|param| match param {
            GraphParameter::Query(info) => Some(ParameterView::new(self, info)),
            _ => None,
        })
    }

    /// Returns a view of the request body, if present.
    #[inline]
    pub fn request(&self) -> Option<RequestView<'graph, 'a>> {
        self.op.request.as_ref().map(|ty| match ty {
            GraphRequest::Json(index) => RequestView::Json(TypeView::new(self.cooked, *index)),
            GraphRequest::Multipart => RequestView::Multipart,
        })
    }

    /// Returns a view of the response body, if present.
    #[inline]
    pub fn response(&self) -> Option<ResponseView<'graph, 'a>> {
        self.op.response.as_ref().map(|ty| match ty {
            GraphResponse::Json(index) => ResponseView::Json(TypeView::new(self.cooked, *index)),
        })
    }

    /// Returns the resource name that this operation declares
    /// in its `x-resource-name` extension field.
    #[inline]
    pub fn resource(&self) -> Option<&'a str> {
        self.op.resource
    }
}

impl<'graph, 'a> View<'graph, 'a> for OperationView<'graph, 'a> {
    /// Returns an iterator over all the inline types that are
    /// contained within this operation's referenced types.
    #[inline]
    fn inlines(&self) -> impl Iterator<Item = InlineTypeView<'graph, 'a>> + use<'graph, 'a> {
        let cooked = self.cooked;
        // Follow edges to inline schemas, skipping shadow edges.
        // See `GraphEdge::shadow()` for an explanation.
        let filtered = EdgeFiltered::from_fn(&cooked.graph, |e| {
            !e.weight().shadow() && matches!(cooked.graph[e.target()], GraphType::Inline(_))
        });
        let mut bfs = {
            let stack: VecDeque<_> = self
                .op
                .types()
                .copied()
                .filter(|&index| {
                    // Exclude operation types that aren't inline schemas;
                    // those types, and their inlines, are already emitted
                    // as named schema types.
                    matches!(cooked.graph[index], GraphType::Inline(_))
                })
                .collect();
            let mut discovered = self.cooked.graph.visit_map();
            discovered.extend(stack.iter().copied().map(NodeIndex::index));
            Bfs { stack, discovered }
        };
        // Unlike `View::inlines()`, we include the starting nodes:
        // the operation contains types; it's not a type itself.
        std::iter::from_fn(move || bfs.next(&filtered)).filter_map(|index| {
            match cooked.graph[index] {
                GraphType::Inline(ty) => Some(InlineTypeView::new(cooked, index, ty)),
                _ => None,
            }
        })
    }

    /// Returns an empty iterator. Operations aren't "used by" other operations;
    /// they use types.
    #[inline]
    fn used_by(&self) -> impl Iterator<Item = OperationView<'graph, 'a>> + use<'graph, 'a> {
        std::iter::empty()
    }

    #[inline]
    fn dependencies(&self) -> impl Iterator<Item = TypeView<'graph, 'a>> + use<'graph, 'a> {
        let cooked = self.cooked;
        cooked.metadata.uses[self.op]
            .ones()
            .map(NodeIndex::new)
            .map(|index| TypeView::new(cooked, index))
    }

    /// Returns an empty iterator. Operations don't have dependents.
    #[inline]
    fn dependents(&self) -> impl Iterator<Item = TypeView<'graph, 'a>> + use<'graph, 'a> {
        std::iter::empty()
    }

    #[inline]
    fn hashable(&self) -> bool {
        false
    }

    #[inline]
    fn defaultable(&self) -> bool {
        false
    }
}

/// A graph-aware view of operation's path template and parameters.
#[derive(Clone, Copy, Debug)]
pub struct OperationViewPath<'view, 'graph, 'a>(&'view OperationView<'graph, 'a>);

impl<'view, 'graph, 'a> OperationViewPath<'view, 'graph, 'a> {
    /// Returns an iterator over this path's segments.
    #[inline]
    pub fn segments(self) -> std::slice::Iter<'view, PathSegment<'a>> {
        self.0.op.path.segments.iter()
    }

    /// Returns an iterator over any literal query parameters
    /// after the path template.
    #[inline]
    pub fn query(self) -> std::slice::Iter<'view, PathQueryParameter<'a>> {
        self.0.op.path.query.iter()
    }

    /// Returns an iterator over this operation's path parameters.
    #[inline]
    pub fn params(self) -> impl Iterator<Item = ParameterView<'view, 'graph, 'a, PathParameter>> {
        self.0.op.params.iter().filter_map(|param| match param {
            GraphParameter::Path(info) => Some(ParameterView::new(self.0, info)),
            _ => None,
        })
    }
}

/// A graph-aware view of an operation parameter.
#[derive(Debug)]
pub struct ParameterView<'view, 'graph, 'a, T> {
    op: &'view OperationView<'graph, 'a>,
    info: &'a GraphParameterInfo<'a>,
    phantom: PhantomData<T>,
}

impl<'view, 'graph, 'a, T> ParameterView<'view, 'graph, 'a, T> {
    #[inline]
    pub(in crate::ir) fn new(
        op: &'view OperationView<'graph, 'a>,
        info: &'a GraphParameterInfo<'a>,
    ) -> Self {
        Self {
            op,
            info,
            phantom: PhantomData,
        }
    }

    /// Returns the parameter name.
    #[inline]
    pub fn name(&self) -> &'a str {
        self.info.name
    }

    /// Returns a view of the parameter's type.
    #[inline]
    pub fn ty(&self) -> TypeView<'graph, 'a> {
        TypeView::new(self.op.cooked, self.info.ty)
    }

    /// Returns `true` if this parameter is required.
    #[inline]
    pub fn required(&self) -> bool {
        self.info.required
    }

    /// Returns the serialization style, if specified.
    #[inline]
    pub fn style(&self) -> Option<ParameterStyle> {
        self.info.style
    }
}

impl<'view, 'graph, 'a, T> View<'graph, 'a> for ParameterView<'view, 'graph, 'a, T> {
    fn inlines(
        &self,
    ) -> impl Iterator<Item = InlineTypeView<'graph, 'a>> + use<'view, 'graph, 'a, T> {
        let cooked = self.op.cooked;
        let start = self.info.ty;
        // Follow edges to inline schemas, skipping shadow edges.
        // See `GraphEdge::shadow()` for an explanation.
        let filtered = EdgeFiltered::from_fn(&cooked.graph, |e| {
            !e.weight().shadow() && matches!(cooked.graph[e.target()], GraphType::Inline(_))
        });
        let mut bfs = {
            // Exclude parameter types that aren't inline schemas;
            // those types, and their inlines, are already emitted as
            // named schema types.
            let stack = match cooked.graph[start] {
                GraphType::Inline(_) => std::iter::once(start).collect(),
                _ => VecDeque::new(),
            };
            let mut discovered = cooked.graph.visit_map();
            discovered.extend(stack.iter().copied().map(NodeIndex::index));
            Bfs { stack, discovered }
        };
        // Unlike `View::inlines()`, we include the starting node:
        // the parameter references a type; it's not a type itself.
        std::iter::from_fn(move || bfs.next(&filtered)).filter_map(|index| {
            match cooked.graph[index] {
                GraphType::Inline(ty) => Some(InlineTypeView::new(cooked, index, ty)),
                _ => None,
            }
        })
    }

    fn used_by(
        &self,
    ) -> impl Iterator<Item = OperationView<'graph, 'a>> + use<'view, 'graph, 'a, T> {
        std::iter::once(OperationView::new(self.op.cooked, self.op.op))
    }

    fn dependencies(
        &self,
    ) -> impl Iterator<Item = TypeView<'graph, 'a>> + use<'view, 'graph, 'a, T> {
        let cooked = self.op.cooked;
        cooked
            .metadata
            .closure
            .dependencies_of(self.info.ty)
            .map(|index| TypeView::new(cooked, index))
    }

    /// Returns an empty iterator; other types don't depend on parameters.
    fn dependents(&self) -> impl Iterator<Item = TypeView<'graph, 'a>> + use<'view, 'graph, 'a, T> {
        std::iter::empty()
    }

    #[inline]
    fn hashable(&self) -> bool {
        self.op.cooked.metadata.hashable[self.info.ty.index()]
    }

    #[inline]
    fn defaultable(&self) -> bool {
        self.op.cooked.metadata.defaultable[self.info.ty.index()]
    }
}

/// A marker type for a path parameter.
#[derive(Clone, Copy, Debug)]
pub enum PathParameter {}

/// A marker type for a query parameter.
#[derive(Clone, Copy, Debug)]
pub enum QueryParameter {}

/// A graph-aware view of an operation's request body.
#[derive(Debug)]
pub enum RequestView<'graph, 'a> {
    Json(TypeView<'graph, 'a>),
    Multipart,
}

/// A graph-aware view of an operation's response body.
#[derive(Debug)]
pub enum ResponseView<'graph, 'a> {
    Json(TypeView<'graph, 'a>),
}