/**
 * Key conversion between the SDK's camelCase declarations and the platform's
 * snake_case API. Purely mechanical — the same rule the HTTP client applies —
 * so a field added to the API is usable from the SDK the day it ships, under
 * its camelCase twin, with no glossary and no SDK release.
 *
 * JSON Schema subtrees are never touched: property names are the author's
 * (and already snake_case by convention), and schema keywords such as
 * `additionalProperties`, `visibleOn` or `$schema` must survive verbatim.
 */

const SCHEMA_KEYS = new Set([
  "schema",
  "values",
  "uiSchema",
  "ui_schema",
  "parameters",
  "results",
]);

export const snakeCase = (key: string): string =>
  key
    .replace(/([a-z0-9])([A-Z])/g, "$1_$2")
    .replace(/([A-Z])([A-Z][a-z])/g, "$1_$2")
    .toLowerCase();

export const camelCase = (key: string): string =>
  key.replace(/_([a-z0-9])/g, (_, c: string) => c.toUpperCase());

type Json = unknown;

/**
 * Deep camelCase → snake_case on object keys. Values under a schema-carrying
 * key (`schema`, `values`, `uiSchema`) are copied as they are. `parameters`
 * and `results` are action-spec envelopes: their own keys convert (`schema`),
 * what is inside `schema` does not.
 */
export function toApiKeys(value: Json, insideSchema = false): Json {
  if (Array.isArray(value)) return value.map((v) => toApiKeys(v, insideSchema));
  if (!value || typeof value !== "object") return value;
  const out: Record<string, Json> = {};
  for (const [k, v] of Object.entries(value as Record<string, Json>)) {
    if (v === undefined) continue;
    if (insideSchema) {
      out[k] = toApiKeys(v, true);
      continue;
    }
    const key = snakeCase(k);
    if (
      k === "schema" ||
      k === "values" ||
      k === "uiSchema" ||
      k === "ui_schema"
    ) {
      out[key] = v; // verbatim
    } else if (k === "parameters" || k === "results") {
      out[key] = toApiKeys(v, false);
    } else {
      out[key] = toApiKeys(v, false);
    }
  }
  return out;
}

/** Deep snake_case → camelCase on object keys, with the same schema exemption. */
export function fromApiKeys(value: Json): Json {
  if (Array.isArray(value)) return value.map(fromApiKeys);
  if (!value || typeof value !== "object") return value;
  const out: Record<string, Json> = {};
  for (const [k, v] of Object.entries(value as Record<string, Json>)) {
    const key = camelCase(k);
    out[key] =
      SCHEMA_KEYS.has(k) && k !== "parameters" && k !== "results"
        ? v
        : fromApiKeys(v);
  }
  return out;
}

/** The plural the manifest uses for a kind: `service_specification` → `service_specifications`. */
export function pluralKind(kind: string): string {
  if (/[^aeiou]y$/.test(kind)) return kind.slice(0, -1) + "ies";
  if (/(s|x|ch|sh)$/.test(kind)) return kind + "es";
  return kind + "s";
}