#!/usr/bin/env node

// Lightweight, dependency-free OpenAPI consistency check: valid YAML, every internal
// $ref resolves, and every path/schema referenced by a $ref actually exists. This is
// not a full OpenAPI 3.1 schema validator, but it catches the class of error that
// actually breaks generated clients and docs sites: dangling references and typos.

import fs from "node:fs";
import process from "node:process";
import yaml from "js-yaml";

const path = "docs/api/openapi.yaml";
const document = yaml.load(fs.readFileSync(path, "utf8"));

const errors = [];

function resolveRef(ref) {
  if (!ref.startsWith("#/")) {
    errors.push(`External or malformed $ref not supported: ${ref}`);
    return;
  }

  const segments = ref
    .slice(2)
    .split("/")
    .map((segment) => segment.replace(/~1/g, "/").replace(/~0/g, "~"));

  let cursor = document;
  for (const segment of segments) {
    if (cursor === undefined || cursor === null || !(segment in cursor)) {
      errors.push(`Dangling $ref: ${ref}`);
      return;
    }
    cursor = cursor[segment];
  }
}

function walk(node) {
  if (Array.isArray(node)) {
    for (const item of node) {
      walk(item);
    }
    return;
  }

  if (node && typeof node === "object") {
    for (const [key, value] of Object.entries(node)) {
      if (key === "$ref" && typeof value === "string") {
        resolveRef(value);
      } else {
        walk(value);
      }
    }
  }
}

if (!document || typeof document !== "object") {
  errors.push("Document did not parse to an object.");
} else {
  if (document.openapi === undefined) {
    errors.push("Missing top-level 'openapi' version field.");
  }
  if (!document.paths || Object.keys(document.paths).length === 0) {
    errors.push("No paths defined.");
  }
  walk(document);
}

if (errors.length > 0) {
  console.error("OpenAPI validation failed:");
  for (const error of errors) {
    console.error(`- ${error}`);
  }
  process.exit(1);
}

const pathCount = Object.keys(document.paths ?? {}).length;
const schemaCount = Object.keys(document.components?.schemas ?? {}).length;
console.log(`OpenAPI document is well-formed: ${pathCount} paths, ${schemaCount} schemas, all $ref pointers resolve.`);