import { Parser } from 'expr-eval-fork';

import type { DashboardVariables } from '../custom/model/dashboard.types.js';

const LOOKUP_VARIABLE_PATH_RE = /lookup\(\s*\$variables((?:\.[a-zA-Z_][a-zA-Z0-9_]*)+)\s*,/g;

const CALC_PARSER_OPTIONS = {

allowMemberAccess: false,

operators: {

assignment: false,

concatenate: false,

conditional: true,

comparison: true,

fndef: false,

in: false,

logical: true,

random: false,

},

} as const;

export function evaluateCalc(

calc: string,

values: Record<string, unknown>,

variables: DashboardVariables = {},

) {

const parser = createCalcParser(variables);

return parser.parse(normalizeLookupPaths(calc)).evaluate(normalizeCalcValues(values));

}

function createCalcParser(variables: DashboardVariables) {

const parser = new Parser(CALC_PARSER_OPTIONS);

parser.functions.lookup = (path: string | number, key: string | number, defaultValue = 0) => {

const map = resolveVariablePath(variables, String(path));

const value = isRecord(map) && Object.prototype.hasOwnProperty.call(map, String(key))

? map[String(key)]

: defaultValue;

return toFiniteNumber(value);

};

return parser;

}

function normalizeLookupPaths(calc: string) {

return calc.replace(LOOKUP_VARIABLE_PATH_RE, (_match, path: string) => {

return `lookup("${path.replace(/^\./, '')}",`;

});

}

function normalizeCalcValues(values: Record<string, unknown>) {

return Object.fromEntries(Object.entries(values).map(([key, value]) => [

key,

typeof value === 'string' ? value : toFiniteNumber(value),

]));

}

function toFiniteNumber(value: unknown) {

const numberValue = typeof value === 'number' ? value : Number(value);

return Number.isFinite(numberValue) ? numberValue : 0;

}

function resolveVariablePath(variables: DashboardVariables, path: string) {

return path

.split('.')

.filter(Boolean)

.reduce<unknown>((current, segment) => isRecord(current) ? current[segment] : undefined, variables);

}

function isRecord(value: unknown): value is Record<string, any> {

return typeof value === 'object' && value !== null;

}