onetaskgraph-plugin-api 0.9.2

//! The by-origin listings' default bodies, met the way a plugin that implements neither meets
//! them: through `dyn`, over a listing that pages, so the default's walk and its own cursor are
//! what is proven.

use std::sync::atomic::{AtomicUsize, Ordering};

use onetaskgraph_plugin_api::{
    Capabilities, Cursor, DependencyEdge, DependencySupport, Direction, Document, DocumentQuery,
    Health, Label, NativeId, Page, PageRequest, Project, ProjectQuery, SourceError, Status,
    StatusCategory, Support, Task, TaskQuery, TaskSource,
};
use serde_json::json;

/// A source holding `projects` and `documents`, each listed two a page whatever the caller
/// asks for — or, as `paging` says, listed the way a defective source lists them. One holding
/// no documents records none at all, and refuses a document listing as such a source does.
struct Listing {
    projects: Vec<Project>,
    documents: Vec<Document>,
    paging: Paging,
    pages: AtomicUsize,
}

/// How a [`Listing`] pages what it holds.
#[derive(Clone, Copy, PartialEq, Eq)]
enum Paging {
    /// Two a page, and the position of the next as its cursor.
    Honest,
    /// Three a page, one more than any page the caller asks for here.
    Overran,
    /// Two a page, and the cursor `0` after every one — the cursor it was given, from the
    /// second page on.
    Repeats,
    /// Two a page, and cursors that cycle: `2` after the first page and `0` after the second,
    /// so no page repeats the cursor it was just given and the walk still never ends.
    Cycles,
}

impl Listing {
    fn of(projects: Vec<Project>, documents: Vec<Document>, paging: Paging) -> Self {
        Self {
            projects,
            documents,
            paging,
            pages: AtomicUsize::new(0),
        }
    }

    fn page<T: Clone>(&self, held: &[T], page: &PageRequest) -> Page<T> {
        self.pages.fetch_add(1, Ordering::SeqCst);
        let start: usize = page.cursor.as_ref().map_or(0, |cursor| {
            cursor.0.parse().expect("a cursor this source gave")
        });
        let size = if self.paging == Paging::Overran { 3 } else { 2 };
        let end = (start + size).min(held.len());
        let next = match self.paging {
            Paging::Repeats => Some(Cursor("0".to_owned())),
            Paging::Cycles => Some(Cursor(if start == 0 { "2" } else { "0" }.to_owned())),
            _ => (end < held.len()).then(|| Cursor(end.to_string())),
        };
        Page {
            items: held[start..end].to_vec(),
            next,
        }
    }
}

fn document(id: &str, origin: Option<serde_json::Value>) -> Document {
    Document {
        version: None,
        id: NativeId::from(id),
        title: format!("Document {id}"),
        content: None,
        project: None,
        labels: Vec::new(),
        url: None,
        location: None,
        created_at: None,
        updated_at: None,
        metadata: origin
            .map(|origin| [(TaskQuery::ORIGIN_KEY.to_owned(), origin)].into())
            .unwrap_or_default(),
        repositories: Vec::new(),
        classification: Default::default(),
    }
}

fn project(id: &str, origin: Option<serde_json::Value>) -> Project {
    Project {
        version: None,
        id: NativeId::from(id),
        title: format!("Project {id}"),
        content: None,
        status: Status {
            category: StatusCategory::Todo,
            name: "Todo".to_owned(),
        },
        labels: Vec::new(),
        url: None,
        location: None,
        created_at: None,
        updated_at: None,
        metadata: origin
            .map(|origin| [(TaskQuery::ORIGIN_KEY.to_owned(), origin)].into())
            .unwrap_or_default(),
        repositories: Vec::new(),
        classification: Default::default(),
    }
}

#[async_trait::async_trait]
impl TaskSource for Listing {
    fn kind(&self) -> &'static str {
        "listing"
    }
    fn capabilities(&self) -> Capabilities {
        Capabilities {
            projects: Support::Native,
            documents: if self.documents.is_empty() {
                Support::Unsupported
            } else {
                Support::Native
            },
            comments: Support::Unsupported,
            assets: Support::Unsupported,
            priority: Support::Unsupported,
            filter_by_priority: Support::Unsupported,
            filter_by_comment_activity: Support::Unsupported,
            filter_by_metadata: Support::Unsupported,
            filter_by_origin: Support::Unsupported,
            reconcile_status: Support::Unsupported,
            complete_by_issue: Support::Unsupported,
            orphan_tasks: Support::Native,
            filter_by_label: Support::Unsupported,
            filter_by_status: Support::Unsupported,
            search_title: Support::Unsupported,
            search_content: Support::Unsupported,
            task_dependencies: DependencySupport::BothDirections,
            project_dependencies: DependencySupport::BothDirections,
            max_page_size: 2,
        }
    }
    async fn health(&self) -> Result<Health, SourceError> {
        Ok(Health {
            reachable: true,
            detail: None,
        })
    }
    async fn get_task(&self, _id: &NativeId) -> Result<Option<Task>, SourceError> {
        Ok(None)
    }
    async fn get_project(&self, _id: &NativeId) -> Result<Option<Project>, SourceError> {
        Ok(None)
    }
    async fn query_tasks(
        &self,
        _query: &TaskQuery,
        _page: &PageRequest,
    ) -> Result<Page<Task>, SourceError> {
        Ok(Page::last(Vec::new()))
    }
    async fn query_projects(
        &self,
        _query: &ProjectQuery,
        page: &PageRequest,
    ) -> Result<Page<Project>, SourceError> {
        Ok(self.page(&self.projects, page))
    }
    async fn query_documents(
        &self,
        _query: &DocumentQuery,
        page: &PageRequest,
    ) -> Result<Page<Document>, SourceError> {
        if self.documents.is_empty() {
            return Err(onetaskgraph_plugin_api::documentless(self.kind()));
        }
        Ok(self.page(&self.documents, page))
    }
    async fn labels(&self, _page: &PageRequest) -> Result<Page<Label>, SourceError> {
        Ok(Page::last(Vec::new()))
    }
    async fn task_dependencies(
        &self,
        _id: &NativeId,
        _direction: Direction,
        _page: &PageRequest,
    ) -> Result<Page<DependencyEdge>, SourceError> {
        Ok(Page::last(Vec::new()))
    }
    async fn project_dependencies(
        &self,
        _id: &NativeId,
        _direction: Direction,
        _page: &PageRequest,
    ) -> Result<Page<DependencyEdge>, SourceError> {
        Ok(Page::last(Vec::new()))
    }
}

fn ids(page: &Page<Project>) -> Vec<&str> {
    page.items
        .iter()
        .map(|project| project.id.0.as_str())
        .collect()
}

#[tokio::test]
async fn the_default_lists_exactly_the_projects_recording_that_origin_across_its_own_pages() {
    let source: Box<dyn TaskSource> = Box::new(Listing::of(
        vec![
            project("A", Some(json!("plans:P-1"))),
            project("B", None),
            project("C", Some(json!("plans:P-10"))),
            project("D", Some(json!("plans:P-1"))),
            project("E", Some(json!(["plans:P-1"]))),
            project("F", Some(json!("plans:P-1"))),
        ],
        Vec::new(),
        Paging::Honest,
    ));

    // A page smaller than the matches walks them in the listing's order, by a cursor of the
    // default's own, and every page reads the listing to its end.
    let first = source
        .query_projects_by_origin(
            "plans:P-1",
            &PageRequest {
                cursor: None,
                limit: 2,
            },
        )
        .await
        .expect("the default answers");
    assert_eq!(ids(&first), ["A", "D"]);
    let second = source
        .query_projects_by_origin(
            "plans:P-1",
            &PageRequest {
                cursor: first.next.clone(),
                limit: 2,
            },
        )
        .await
        .expect("the default answers its own cursor");
    assert_eq!(
        ids(&second),
        ["F"],
        "a prefix of the origin, another origin and a value that is no string never match"
    );
    assert_eq!(second.next, None);

    // An origin nothing records is an empty answer, never a failure.
    let none = source
        .query_projects_by_origin(
            "plans:P-2",
            &PageRequest {
                cursor: None,
                limit: 10,
            },
        )
        .await
        .expect("the default answers");
    assert!(none.items.is_empty() && none.next.is_none());

    // A cursor it did not hand out is refused rather than read as a position.
    let refused = source
        .query_projects_by_origin(
            "plans:P-1",
            &PageRequest {
                cursor: Some(Cursor("4".to_owned())),
                limit: 2,
            },
        )
        .await
        .expect_err("a foreign cursor");
    assert!(
        matches!(refused, SourceError::Refused { .. }),
        "{refused:?}"
    );
}

#[tokio::test]
async fn the_document_default_refuses_on_a_source_with_no_documents_as_its_listing_does() {
    let source: Box<dyn TaskSource> = Box::new(Listing::of(Vec::new(), Vec::new(), Paging::Honest));
    let refused = source
        .query_documents_by_origin(
            "plans:D-1",
            &PageRequest {
                cursor: None,
                limit: 2,
            },
        )
        .await
        .expect_err("a source with no documents");
    assert_eq!(refused, onetaskgraph_plugin_api::documentless("listing"));
}

fn first(limit: u32) -> PageRequest {
    PageRequest {
        cursor: None,
        limit,
    }
}

#[tokio::test]
async fn the_document_default_lists_exactly_the_documents_recording_that_origin_across_pages() {
    let source: Box<dyn TaskSource> = Box::new(Listing::of(
        Vec::new(),
        vec![
            document("A", Some(json!("plans:D-1"))),
            document("B", Some(json!("plans:D-10"))),
            document("C", None),
            document("D", Some(json!("plans:D-1"))),
            document("E", Some(json!("other:D-1"))),
            document("F", Some(json!("plans:D-1"))),
        ],
        Paging::Honest,
    ));
    let page_one = source
        .query_documents_by_origin("plans:D-1", &first(2))
        .await
        .expect("the default answers");
    let ids = |page: &Page<Document>| -> Vec<String> {
        page.items
            .iter()
            .map(|document| document.id.0.clone())
            .collect()
    };
    assert_eq!(ids(&page_one), ["A", "D"]);
    let page_two = source
        .query_documents_by_origin(
            "plans:D-1",
            &PageRequest {
                cursor: page_one.next.clone(),
                limit: 2,
            },
        )
        .await
        .expect("the default answers its own cursor");
    assert_eq!(ids(&page_two), ["F"]);
    assert_eq!(page_two.next, None);
}

#[tokio::test]
async fn a_listing_that_overruns_its_page_or_repeats_its_cursor_is_refused_by_either_default() {
    for paging in [Paging::Overran, Paging::Repeats, Paging::Cycles] {
        let source: Box<dyn TaskSource> = Box::new(Listing::of(
            (0..6)
                .map(|n| project(&format!("P{n}"), Some(json!("plans:X"))))
                .collect(),
            (0..6)
                .map(|n| document(&format!("D{n}"), Some(json!("plans:X"))))
                .collect(),
            paging,
        ));
        let projects = source
            .query_projects_by_origin("plans:X", &first(2))
            .await
            .expect_err("a defective listing is refused, not narrowed");
        let documents = source
            .query_documents_by_origin("plans:X", &first(2))
            .await
            .expect_err("a defective listing is refused, not narrowed");
        let said = match paging {
            Paging::Overran => "never more",
            _ => "would never end",
        };
        for refused in [projects, documents] {
            assert!(
                matches!(&refused, SourceError::Malformed { message } if message.contains(said)),
                "{refused:?}"
            );
        }
    }
}