import fs from 'node:fs';
import path from 'node:path';
import { createRequire } from 'node:module';
import { findProjectRoot } from '../brownfield/utils/paths.js';
import { loadBrownfieldConfig } from '../config.js';
import type { BrownieConfig } from '../types.js';

const LEGACY_AND_NEW_BROWNIE_CONFIG_ERROR =
  'Cannot use both legacy and new Brownie configuration formats simultaneously. Please migrate to the new configuration format and remove legacy configuration files: https://oss.callstack.com/react-native-brownfield/docs/api-reference/configuration#migrating-from-legacy-brownie-configuration';

interface PackageJson {
  brownie?: BrownieConfig;
}

function loadPackageJson(projectRoot: string = findProjectRoot()): PackageJson {
  const packageJsonPath = path.resolve(projectRoot, 'package.json');

  if (!fs.existsSync(packageJsonPath)) {
    throw new Error('package.json not found');
  }

  return JSON.parse(fs.readFileSync(packageJsonPath, 'utf-8')) as PackageJson;
}

/**
 * Checks if @callstack/brownie package is installed.
 */
export function isBrownieInstalled(
  projectRoot: string = findProjectRoot()
): boolean {
  const require = createRequire(path.join(projectRoot, 'package.json'));
  try {
    require.resolve('@callstack/brownie/package.json');
    return true;
  } catch {
    return false;
  }
}

/**
 * Resolves the path to the @callstack/brownie package.
 */
export function getBrowniePackagePath(
  projectRoot: string = findProjectRoot()
): string {
  const require = createRequire(path.join(projectRoot, 'package.json'));
  try {
    const browniePackageJson =
      require.resolve('@callstack/brownie/package.json');
    return path.dirname(browniePackageJson);
  } catch {
    throw new Error(
      "@callstack/brownie is not installed. Run 'npm install @callstack/brownie' or 'yarn add @callstack/brownie'"
    );
  }
}

/**
 * Returns the output path for generated Swift files.
 */
export function getSwiftOutputPath(
  projectRoot: string = findProjectRoot()
): string {
  const browniePath = getBrowniePackagePath(projectRoot);
  return path.join(browniePath, 'ios', 'Generated');
}

/**
 * Returns whether package.json contains legacy brownie config.
 */
export function hasLegacyConfig(
  projectRoot: string = findProjectRoot()
): boolean {
  const packageJson = loadPackageJson(projectRoot);

  return Object.prototype.hasOwnProperty.call(packageJson, 'brownie');
}

/**
 * Loads brownie config from package.json in the current working directory.
 */
export function loadConfig(
  projectRoot: string = findProjectRoot()
): BrownieConfig {
  const packageJson = loadPackageJson(projectRoot);

  return packageJson.brownie ?? {};
}

export type ResolveBrownieCodegenConfigOptions = {
  brownie?: BrownieConfig;
  projectRoot?: string;
};

export type ResolvedBrownieCodegenConfig = {
  config: BrownieConfig;
  usedLegacyConfig: boolean;
};

/**
 * Resolves Brownie codegen settings from explicit options, brownfield config,
 * or legacy package.json `brownie` config.
 */
export function resolveBrownieCodegenConfig({
  brownie,
  projectRoot = findProjectRoot(),
}: ResolveBrownieCodegenConfigOptions = {}): ResolvedBrownieCodegenConfig {
  const legacyConfig = hasLegacyConfig(projectRoot)
    ? loadConfig(projectRoot)
    : undefined;
  const brownfieldBrownie = loadBrownfieldConfig(projectRoot).brownie;

  if (legacyConfig !== undefined && (brownie ?? brownfieldBrownie)) {
    throw new Error(LEGACY_AND_NEW_BROWNIE_CONFIG_ERROR);
  }

  if (legacyConfig !== undefined) {
    return {
      config: legacyConfig,
      usedLegacyConfig: true,
    };
  }

  return {
    config: brownie ?? brownfieldBrownie ?? {},
    usedLegacyConfig: false,
  };
}