import fs from 'node:fs';
import os from 'node:os';
import path from 'node:path';
import { execSync } from 'node:child_process';
import { logger } from '@rock-js/tools';

interface SliceConfig {
  target: string;
  /** Additional targets for fat binaries */
  additionalTargets?: string[];
}

const SLICE_CONFIGS: Record<string, SliceConfig> = {
  'ios-arm64': {
    target: 'arm64-apple-ios15.0',
  },
  'ios-arm64_x86_64-simulator': {
    target: 'arm64-apple-ios15.0-simulator',
    additionalTargets: ['x86_64-apple-ios15.0-simulator'],
  },
};

/**
 * Creates an empty static library for the given target.
 */
function createEmptyStaticLib(target: string): string {
  const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'framework-strip-'));
  const tempObj = path.join(tempDir, 'empty.o');
  const tempLib = path.join(tempDir, 'empty.a');

  try {
    execSync(
      `echo "" | xcrun clang -x c -c - -o "${tempObj}" -target ${target}`,
      {
        stdio: 'pipe',
      }
    );

    execSync(`xcrun ar rcs "${tempLib}" "${tempObj}"`, {
      stdio: 'pipe',
    });
  } catch (error) {
    fs.rmSync(tempDir, { recursive: true });
    throw new Error(
      `Failed to create empty static library for target ${target}: ${error instanceof Error ? error.message : error}`
    );
  }

  fs.unlinkSync(tempObj);

  return tempLib;
}

/**
 * Creates a fat static library combining multiple architectures.
 */
function createFatStaticLib(targets: string[]): string {
  const libs = targets.map((target) => createEmptyStaticLib(target));

  const outputDir = fs.mkdtempSync(
    path.join(os.tmpdir(), 'framework-strip-fat-')
  );
  const outputLib = path.join(outputDir, 'fat.a');

  try {
    execSync(
      `xcrun lipo -create ${libs.map((l) => `"${l}"`).join(' ')} -output "${outputLib}"`,
      {
        stdio: 'pipe',
      }
    );
  } catch (error) {
    libs.forEach((lib) => fs.rmSync(path.dirname(lib), { recursive: true }));
    fs.rmSync(outputDir, { recursive: true });
    throw new Error(
      `Failed to create fat static library: ${error instanceof Error ? error.message : error}`
    );
  }

  libs.forEach((lib) => {
    fs.unlinkSync(lib);
    fs.rmSync(path.dirname(lib), { recursive: true });
  });

  return outputLib;
}

/**
 * Strips the binary from an xcframework, keeping only Swift module interfaces.
 * This creates an "interface-only" framework where consumers can import the module
 * but the actual symbols must come from another framework (e.g., BrownfieldLib).
 *
 * @param xcframeworkPath - Path to the .xcframework directory
 */
export function stripFrameworkBinary(xcframeworkPath: string): void {
  if (!fs.existsSync(xcframeworkPath)) {
    throw new Error(`XCFramework not found at: ${xcframeworkPath}`);
  }

  const frameworkName = path.basename(xcframeworkPath, '.xcframework');

  logger.info(
    `Stripping binary from ${frameworkName}.xcframework (interface-only)...`
  );

  const slices = fs.readdirSync(xcframeworkPath).filter((entry) => {
    const fullPath = path.join(xcframeworkPath, entry);
    return fs.statSync(fullPath).isDirectory() && entry.startsWith('ios-');
  });

  for (const sliceName of slices) {
    const frameworkDir = path.join(
      xcframeworkPath,
      sliceName,
      `${frameworkName}.framework`
    );
    const binaryPath = path.join(frameworkDir, frameworkName);

    if (!fs.existsSync(binaryPath)) {
      logger.warn(`No binary found at ${binaryPath}, skipping`);
      continue;
    }

    const config = SLICE_CONFIGS[sliceName];
    if (!config) {
      logger.warn(`Unknown slice type: ${sliceName}, skipping`);
      continue;
    }

    let emptyLib: string;
    if (config.additionalTargets) {
      // Create fat library for multiple architectures
      emptyLib = createFatStaticLib([
        config.target,
        ...config.additionalTargets,
      ]);
    } else {
      // Create single-arch library
      emptyLib = createEmptyStaticLib(config.target);
    }

    // Replace original binary with empty stub
    fs.copyFileSync(emptyLib, binaryPath);
    fs.unlinkSync(emptyLib);
    fs.rmSync(path.dirname(emptyLib), { recursive: true });
  }

  logger.success(`${frameworkName}.xcframework is now interface-only`);
}