/**
 * Pure JSON-to-TypeScript-source printer.
 *
 * This module is the second stage of the codec → TS pipeline:
 *
 *     jsValue  →  codec.encodeJson  →  JsonValue  →  jsonToTsSource  →  TS source text
 *
 * Stage 1 (`codec.encodeJson`) is a codec responsibility — date serialization,
 * opaque domain types (vector, bigint, uuid), JSON canonicalization. Stage 2
 * (this module) is a pure JSON-to-TS printer that must never grow type-specific
 * branches.
 *
 * To render a non-JSON JS value (Date, Vector, BigInt, Buffer, …), encode it
 * through the relevant codec's `encodeJson` first. Adding special cases to
 * this file is not the answer — that's what codecs are for.
 */

export type JsonValue = string | number | boolean | null | readonly JsonValue[] | JsonObject;
export type JsonObject = { readonly [key: string]: JsonValue | undefined };

/**
 * Render a JSON-compatible value as a TypeScript source-text literal.
 *
 * Accepts `unknown` for ergonomics with structural types (e.g. `ColumnSpec`,
 * `ForeignKeySpec`) whose fields are all JSON-compatible but whose interfaces
 * lack the index signature TypeScript requires for `JsonObject` assignability.
 * Non-JSON values (Date, Symbol, Function, etc.) throw at runtime.
 */
export function jsonToTsSource(value: unknown): string {
  if (value === undefined) return 'undefined';
  if (value === null) return 'null';
  if (typeof value === 'string') return JSON.stringify(value);
  if (typeof value === 'number' || typeof value === 'boolean') return String(value);
  if (Array.isArray(value)) {
    if (value.length === 0) return '[]';
    const items = value.map((v: unknown) => jsonToTsSource(v));
    const singleLine = `[${items.join(', ')}]`;
    if (singleLine.length <= 80) return singleLine;
    return `[\n${items.map((i) => `  ${i}`).join(',\n')},\n]`;
  }
  if (typeof value === 'object') {
    const entries = Object.entries(value).filter(([, v]) => v !== undefined);
    if (entries.length === 0) return '{}';
    const items = entries.map(([k, v]) => `${renderKey(k)}: ${jsonToTsSource(v)}`);
    const singleLine = `{ ${items.join(', ')} }`;
    if (singleLine.length <= 80) return singleLine;
    return `{\n${items.map((i) => `  ${i}`).join(',\n')},\n}`;
  }
  throw new Error(`jsonToTsSource: unsupported value type "${typeof value}"`);
}

function renderKey(key: string): string {
  if (key === '__proto__') return JSON.stringify(key);
  return /^[a-zA-Z_$][a-zA-Z0-9_$]*$/.test(key) ? key : JSON.stringify(key);
}