const _ = require("lodash");
const ptr = require("json-pointer");

function resolvePointer(data, rootPath, relativePath) {
    if (relativePath[0] === "/") return ptr.get(data, relativePath);

    const m = relativePath.match(/^(\d+)(.*)/);
    relativePath = m[2];
    for (let i = 0; i < parseInt(m[1]); i++) {
        rootPath = rootPath.replace(/\/[^\/]+$/, "");
    }

    return ptr.get(data, rootPath + relativePath);
}

module.exports = (ajv) =>
    ajv.addKeyword({
        keyword: "sumOf",
        validate: function validate(
            { list, map },
            total,
            _parent,
            { rootData, instancePath }
        ) {
            if (list.$data) {
                list = resolvePointer(rootData, instancePath, list.$data);
            }

            if (map) data = _.map(data, map);

            if (_.sum(list) === total) return true;

            validate.errors = [
                {
                    keyword: "sumOf",
                    message: "should add up to sum total",
                    params: {
                        list,
                    },
                },
            ];

            return false;
        },
        $data: true,
        errors: true,
    });