import type { Tree } from "@nx/devkit";

export type DetectedTestRunner = "jest" | "vitest";
export type DetectedLinter = "eslint" | "biome";
export type DetectedFormatter = "prettier" | "biome" | "eslint-stylistic";

function readRootPackageJson(tree: Tree): Record<string, unknown> | null {
  try {
    const raw = tree.read("package.json", "utf-8");
    if (!raw) return null;
    return JSON.parse(raw) as Record<string, unknown>;
  } catch {
    return null;
  }
}

function hasDep(pkg: Record<string, unknown>, name: string): boolean {
  const deps = (pkg?.dependencies as Record<string, string>) ?? {};
  const devDeps = (pkg?.devDependencies as Record<string, string>) ?? {};
  return Boolean(deps[name] || devDeps[name]);
}

export function detectTestRunnerFromRootPackageJson(tree: Tree): {
  detected: DetectedTestRunner | null;
  candidates: DetectedTestRunner[];
} {
  const pkg = readRootPackageJson(tree) ?? {};
  const candidates: DetectedTestRunner[] = [];
  if (hasDep(pkg, "jest")) candidates.push("jest");
  if (hasDep(pkg, "vitest")) candidates.push("vitest");

  if (candidates.length === 1) {
    return { detected: candidates[0], candidates };
  }
  return { detected: null, candidates };
}

export function detectLinterFromRootPackageJson(tree: Tree): {
  detected: DetectedLinter | null;
  candidates: DetectedLinter[];
} {
  const pkg = readRootPackageJson(tree) ?? {};
  const candidates: DetectedLinter[] = [];
  if (hasDep(pkg, "eslint")) candidates.push("eslint");
  if (hasDep(pkg, "@biomejs/biome")) candidates.push("biome");

  if (candidates.length === 1) {
    return { detected: candidates[0], candidates };
  }
  return { detected: null, candidates };
}

export function detectFormatterFromRootPackageJson(tree: Tree): {
  detected: DetectedFormatter | null;
  candidates: DetectedFormatter[];
} {
  const pkg = readRootPackageJson(tree) ?? {};
  const candidates: DetectedFormatter[] = [];
  if (hasDep(pkg, "prettier")) candidates.push("prettier");
  if (hasDep(pkg, "@biomejs/biome")) candidates.push("biome");
  if (hasDep(pkg, "@stylistic/eslint-plugin"))
    candidates.push("eslint-stylistic");

  if (candidates.length === 1) {
    return { detected: candidates[0], candidates };
  }
  return { detected: null, candidates };
}