import { readFileSync } from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

export const napcatAutomationPromptNames = [
  'upstream-audit',
  'sync-candidate-review',
  'runtime-release-readiness',
  'remote-dev-handoff',
] as const;

export type NapcatAutomationPromptName =
  (typeof napcatAutomationPromptNames)[number];

const promptsRoot = path.resolve(
  fileURLToPath(new URL('../..', import.meta.url)),
  'prompts',
  'napcat',
);
const promptsRootBoundary = promptsRoot.endsWith(path.sep)
  ? promptsRoot
  : `${promptsRoot}${path.sep}`;
const napcatAutomationPromptNameSet = new Set<string>(
  napcatAutomationPromptNames,
);
const napcatAutomationPromptFileNames = {
  'upstream-audit': 'upstream-audit.md',
  'sync-candidate-review': 'sync-candidate-review.md',
  'runtime-release-readiness': 'runtime-release-readiness.md',
  'remote-dev-handoff': 'remote-dev-handoff.md',
} satisfies Record<NapcatAutomationPromptName, string>;

/**
 * Parses an external prompt name into the source-controlled NapCat prompt enum.
 * @param value - Raw prompt name from CLI, JSON, MCP input, or a typed caller; only exact entries in `napcatAutomationPromptNames` are accepted.
 * @returns A stable prompt name that can be mapped to a fixed file under `prompts/napcat`.
 */
export function parseNapcatAutomationPromptName(
  value: string,
): NapcatAutomationPromptName {
  if (napcatAutomationPromptNameSet.has(value)) {
    return value as NapcatAutomationPromptName;
  }
  throw new Error(`Unsupported NapCat automation prompt: ${value}`);
}

/**
 * Loads a source-controlled NapCat automation prompt by stable prompt name.
 * @param name - Prompt identifier from `napcatAutomationPromptNames`; runtime callers may still pass untyped external strings, so the loader re-validates and resolves only fixed filenames.
 * @returns UTF-8 prompt text used by Codex CLI automation.
 */
export function loadNapcatAutomationPrompt(
  name: NapcatAutomationPromptName,
): string {
  const promptName = parseNapcatAutomationPromptName(String(name));
  const promptPath = path.resolve(
    promptsRoot,
    napcatAutomationPromptFileNames[promptName],
  );
  if (!promptPath.startsWith(promptsRootBoundary)) {
    throw new Error(`NapCat automation prompt escaped prompt root: ${name}`);
  }
  return readFileSync(promptPath, 'utf8');
}