// adapted from https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-source-graphql/src/batching/merge-queries.js
export function createPrefix(index) {
    return `_${index}_`;
}
function matchKey(prefixedKey) {
    const match = /^_(\d+)_(.*)$/.exec(prefixedKey);
    if (match && match.length === 3 && !isNaN(Number(match[1])) && match[2]) {
        return { index: Number(match[1]), originalKey: match[2] };
    }
    return null;
}
export function parseKey(prefixedKey) {
    const match = matchKey(prefixedKey);
    if (!match) {
        throw new Error(`Key ${prefixedKey} is not correctly prefixed`);
    }
    return match;
}
export function parseKeyFromPath(path) {
    let keyOffset = 0;
    let match = null;
    // Keep looping over path until we've found a match or path has no more items left
    for (; !match && keyOffset < path.length; keyOffset++) {
        const pathKey = path[keyOffset];
        if (typeof pathKey === 'string') {
            match = matchKey(pathKey);
        }
    }
    if (!match) {
        throw new Error(`Path ${path.join('.')} does not contain correctly prefixed key`);
    }
    return {
        ...match,
        keyOffset,
    };
}