import { readFile, readdir } from "node:fs/promises";
import { fileURLToPath } from "node:url";
import { join } from "node:path";
import type { RuleSetId } from "./detect-project.js";

export const ECC_COMMIT = "623f2c020f052319657674e4e6c29ab5d0ad566b";
export const ECC_REPOSITORY_URL = "https://github.com/affaan-m/ECC";

export type RuleSource = "ecc" | "pi";

export interface RuleDocument {
  ruleSet: RuleSetId;
  relativePath: string;
  content: string;
  source: RuleSource;
}

const ECC_RULES_DIRECTORY = fileURLToPath(new URL("../rules/ecc/", import.meta.url));
const PI_RULES_DIRECTORY = fileURLToPath(new URL("../rules/pi/", import.meta.url));

async function readRuleContent(
  ruleSet: RuleSetId,
  filename: string,
): Promise<{ content: string; source: RuleSource }> {
  try {
    return {
      content: await readFile(join(PI_RULES_DIRECTORY, ruleSet, filename), "utf8"),
      source: "pi",
    };
  } catch (error: unknown) {
    if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
  }

  return {
    content: await readFile(join(ECC_RULES_DIRECTORY, ruleSet, filename), "utf8"),
    source: "ecc",
  };
}

export async function loadRuleDocuments(ruleSets: readonly RuleSetId[]): Promise<RuleDocument[]> {
  const documents: RuleDocument[] = [];

  for (const ruleSet of ruleSets) {
    const directory = join(ECC_RULES_DIRECTORY, ruleSet);
    const filenames = (await readdir(directory, { withFileTypes: true }))
      .filter((entry) => entry.isFile() && entry.name.endsWith(".md"))
      .map((entry) => entry.name)
      .sort((left, right) => left.localeCompare(right));

    const loadedRules = await Promise.all(
      filenames.map((filename) => readRuleContent(ruleSet, filename)),
    );

    documents.push(
      ...filenames.map((filename, index) => ({
        ruleSet,
        relativePath: `${ruleSet}/${filename}`,
        content: loadedRules[index]?.content ?? "",
        source: loadedRules[index]?.source ?? "ecc",
      })),
    );
  }

  return documents;
}