//! Hand-written query plans composed from `scan_atom`, `semijoin`, and `natural_join`.
//!
//! Schema:
//! - `edge(src, dst)`: directed edges
//! - `labeled(node)`: a set of labeled nodes
//!
//! Two rules are executed against the same fixture:
//! - `Q1(X)   :- edge(X, X), labeled(X).`  (labeled self-loops)
//! - `Q2(X, Y) :- edge(X, Y), labeled(Y).`  (edges whose destination is labeled)

use query_ops::atom::{scan_atom, AtomPattern, Term};
use query_ops::join::{natural_join, semijoin};
use query_ops::table::Table;
use query_ops::value::Value;

fn var(name: &str) -> Term {
    Term::Var(name.to_string())
}

fn int(value: i64) -> Value {
    Value::Int(value)
}

#[test]
fn labeled_self_loops_and_edges_into_labeled_nodes() {
    let edge = Table::from_rows(
        2,
        vec![
            vec![int(1), int(2)],
            vec![int(2), int(3)],
            vec![int(3), int(3)],
            vec![int(4), int(1)],
            vec![int(2), int(2)],
        ],
    );
    let labeled = Table::from_rows(1, vec![vec![int(2)], vec![int(3)]]);

    let self_loops = scan_atom(
        &edge,
        &AtomPattern {
            columns: vec![var("X"), var("X")],
        },
    );
    let labeled_x = scan_atom(
        &labeled,
        &AtomPattern {
            columns: vec![var("X")],
        },
    );
    let q1 = semijoin(&self_loops, &labeled_x);
    assert_eq!(q1.columns, vec!["X".to_string()]);
    assert_eq!(q1.rows, vec![vec![int(3)], vec![int(2)]]);

    let edge_xy = scan_atom(
        &edge,
        &AtomPattern {
            columns: vec![var("X"), var("Y")],
        },
    );
    let labeled_y = scan_atom(
        &labeled,
        &AtomPattern {
            columns: vec![var("Y")],
        },
    );
    let q2 = natural_join(&edge_xy, &labeled_y);
    assert_eq!(q2.columns, vec!["X".to_string(), "Y".to_string()]);
    assert_eq!(
        q2.rows,
        vec![
            vec![int(1), int(2)],
            vec![int(2), int(3)],
            vec![int(3), int(3)],
            vec![int(2), int(2)],
        ],
    );
}