@simulacrum/github-api-simulator/dist/esm/graphql/relay.js

Provides common functionality to frontend app and plugins.

const identity = (a) => a;
export function applyRelayPagination(nodes, args, mapper = identity) {
    let range = applyCursorsToEdges(nodes, args.before, args.after);
    let edges = edgesToReturn(range, args.first, args.last).map(edge => ({
        ...edge,
        node: mapper(edge.node),
    }));
    let [first] = edges;
    let last = edges.slice().pop();
    return {
        totalCount: nodes.length,
        edges,
        nodes: edges.map(e => e.node),
        pageInfo: {
            get hasNextPage() {
                let { first, before } = args;
                if (first != null) {
                    return range.length > first;
                }
                else if (before != null) {
                    return Number(before) < range.length - 1;
                }
                return false;
            },
            get hasPreviousPage() {
                let { last, after } = args;
                if (last != null) {
                    return range.length > last;
                }
                else if (after != null) {
                    return Number(after) > 0;
                }
                return false;
            },
            startCursor: first?.cursor,
            endCursor: last?.cursor,
        },
    };
}
function applyCursorsToEdges(nodes, before, after) {
    let afterIdx = !!after ? Number(after) : -1;
    let beforeIdx = !!before ? Number(before) : nodes.length;
    let edges = nodes.slice(afterIdx + 1, beforeIdx).map((node, i) => ({
        node,
        cursor: (afterIdx + 1 + i).toString(),
    }));
    return edges;
}
function edgesToReturn(edges, first, last) {
    let newEdges = [];
    if (first == null && last == null) {
        first = 100;
    }
    if (first != null) {
        if (first < 0) {
            throw new Error(`value of first must be greater than 0, was ${first}`);
        }
        newEdges = edges.slice(0, first);
    }
    if (last != null) {
        if (last < 0) {
            throw new Error(`value of 'after' must be greater than 0, was ${last}`);
        }
        newEdges = edges.slice(-last);
    }
    return newEdges;
}
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