/**
 * Generate a static, importable barrel of a lexicon's post-synth checks.
 *
 * The runtime loader (`discoverPostSynthChecks`) readdir-globs the directory and
 * `require()`s each file via tsx — fs- and tsx-coupled, so it can't run in a
 * bundle or on an edge runtime (Cloudflare Workers). This generator produces a
 * committed `lint/post-synth/index.ts` with explicit static imports + an exported
 * `postSynthChecks` array, which bundlers can follow with no fs/tsx/require. See #409.
 *
 * Detection reuses the runtime's own `isPostSynthCheck`, so the barrel contains
 * exactly the checks discovery would — including files whose export name differs
 * from the filename (docker/helm/temporal) and excluding helper modules
 * (cf-refs, arm-refs, …) that export no check.
 */

import { createRequire } from "module";
import { listRuleFiles } from "../lint/discover";
import { isPostSynthCheck } from "../lint/post-synth";

export interface BarrelEntry {
  /** Module specifier relative to the barrel, e.g. "./gha021" or "./apt-no-recommends". */
  module: string;
  /** Exported binding holding the check, e.g. "gha021" or "dkrd010". */
  exportName: string;
  /** The check's id (e.g. "GHA021"), used for stable ordering. */
  id: string;
}

/**
 * Scan a post-synth directory and return one entry per exported check.
 * Runs at codegen time on Node (tsx-powered require), never in the shipped path.
 */
export function scanPostSynthChecks(dir: string, importMetaUrl: string): BarrelEntry[] {
  const require = createRequire(importMetaUrl);
  const entries: BarrelEntry[] = [];
  for (const file of listRuleFiles(dir)) {
    const base = file.replace(/\.ts$/, "");
    let mod: Record<string, unknown>;
    try {
      mod = require(`${dir}/${base}`) as Record<string, unknown>;
    } catch {
      continue; // a file that fails to load contributes nothing
    }
    for (const [exportName, value] of Object.entries(mod)) {
      if (isPostSynthCheck(value)) {
        entries.push({ module: `./${base}`, exportName, id: value.id });
      }
    }
  }
  return entries;
}

/** Render the barrel file content from scanned entries (pure — easy to unit test). */
export function generatePostSynthBarrel(entries: BarrelEntry[]): string {
  const sorted = [...entries].sort((a, b) => a.id.localeCompare(b.id));
  const lines: string[] = [];
  lines.push("// Code generated by chant generate. DO NOT EDIT.");
  lines.push('import type { PostSynthCheck } from "@intentius/chant/lint/post-synth";');
  for (const e of sorted) {
    lines.push(`import { ${e.exportName} } from ${JSON.stringify(e.module)};`);
  }
  lines.push("");
  lines.push("export const postSynthChecks: PostSynthCheck[] = [");
  for (const e of sorted) {
    lines.push(`  ${e.exportName},`);
  }
  lines.push("];");
  lines.push("");
  return lines.join("\n");
}

/** Scan a directory and render its barrel in one step. */
export function renderPostSynthBarrelForDir(dir: string, importMetaUrl: string): string {
  return generatePostSynthBarrel(scanPostSynthChecks(dir, importMetaUrl));
}