benepass.js

function http_request({url}) {
    console.log("running get-text")
    if (url === "https://www.example.com") {
        return "Hello, world!"
    }
    throw Error('Bad url')
}

function string_reverse({string = ''}) {
    console.log("running reverse-text");
    return string.split('').reverse().join('')
}

function string_length(string = '') {
    return string.length
}

function save_file({filename = "", contents = ""}) {
    console.log("running save-file");
    console.log({filename, contents})
}

const methods = {
    "reverse-string": string_reverse,
    "http-request": http_request,
    "save-file": save_file,
}

const results = {
    "reverse-text": null,
    "get-text": null,
    "save-file": null,
}

const argsResult = {
    "reverse-text": null,
    "get-text": null,
    "save-file": null,
}

function parse_step(step_name, previous_step, graph) {

    if (results[step_name]) return results[step_name]

    const stepType = graph.steps[step_name].type
    const stepArgs = graph.steps[step_name].args

    const argsList = Object.keys(stepArgs)

    for (let argName of argsList) {
        const argType = stepArgs[argName].type
        const argValue = stepArgs[argName].value


        if (argType === 'reference') {
            const parseResult = parse_step(argValue, step_name, graph)
            argsResult[step_name] = argsResult[step_name] ?
                {...argsResult[step_name], [argName]: parseResult} : {[argName]: parseResult}

        } else {
            argsResult[step_name] = {[argName]: argValue}
        }
    }

    results[step_name] = methods[stepType](argsResult[step_name])
    return results[step_name]
}

function solution(graph) {
    const stepNames = Object.keys(graph.steps)

    for (let stepName of stepNames) {
        if (!results[stepName]) {
            results[stepName] = parse_step(stepName, null, graph)
        }
    }
}


const graph = {
    "steps": {
        "reverse-text": {
            "type": "reverse-string",
            "args": {
                "string": {
                    "type": "reference",
                    "value": "get-text"
                }
            }
        },
        "get-text": {
            "type": "http-request",
            "args": {
                "url": {
                    "type": "value",
                    "value": "https://www.example.com"
                }
            }
        },
        "save-file": {
            "type": "save-file",
            "args": {
                "filename": {
                    "type": "value",
                    "value": "/foo.txt"
                },
                "contents": {
                    "type": "reference",
                    "value": "reverse-text"
                }
            }
        }
    }
}


solution(graph)