import { addPath, exportVariable } from '@actions/core'
import { spawn } from 'child_process'
import { rm, writeFile, mkdir, copyFile } from 'fs/promises'
import { readFileSync } from 'fs'
import path from 'path'
import util from 'util'
import { Inputs } from '../inputs'
import { parse as parseYaml } from 'yaml'
import pnpmLock from './bootstrap/pnpm-lock.json'

const BOOTSTRAP_PACKAGE_JSON = JSON.stringify({ private: true, dependencies: { pnpm: pnpmLock.packages['node_modules/pnpm'].version } })

export async function runSelfInstaller(inputs: Inputs): Promise<number> {
  const { version, dest, packageJsonFile, standalone } = inputs
  const { GITHUB_WORKSPACE } = process.env

  // Step 1: Install bootstrap pnpm via npm (integrity verified by committed lockfile)
  const bootstrapDir = path.join(dest, '..', '.pnpm-bootstrap')
  await rm(bootstrapDir, { recursive: true, force: true })
  await mkdir(bootstrapDir, { recursive: true })

  await writeFile(path.join(bootstrapDir, 'package.json'), BOOTSTRAP_PACKAGE_JSON)
  await writeFile(path.join(bootstrapDir, 'package-lock.json'), JSON.stringify(pnpmLock))

  const npmExitCode = await runCommand('npm', ['ci', '--ignore-scripts'], { cwd: bootstrapDir })
  if (npmExitCode !== 0) {
    return npmExitCode
  }

  const bootstrapPnpm = path.join(bootstrapDir, 'node_modules', '.bin', 'pnpm')

  // Step 2: Use bootstrap pnpm to install the target version (verified via project's pnpm-lock.yaml)
  await rm(dest, { recursive: true, force: true })
  await mkdir(dest, { recursive: true })
  const pkgJson = path.join(dest, 'package.json')
  await writeFile(pkgJson, JSON.stringify({ private: true }))

  // copy .npmrc if it exists to install from custom registry
  if (GITHUB_WORKSPACE) {
    try {
      await copyFile(path.join(GITHUB_WORKSPACE, '.npmrc'), path.join(dest, '.npmrc'))
    } catch (error) {
      // Swallow error if .npmrc doesn't exist
      if (!util.types.isNativeError(error) || !('code' in error) || error.code !== 'ENOENT') throw error
    }
  }

  // prepare target pnpm
  const target = await readTarget({ version, packageJsonFile, standalone })
  const installArgs = ['install', target, '--no-lockfile']
  const exitCode = await runCommand(bootstrapPnpm, installArgs, { cwd: dest })
  if (exitCode === 0) {
    const pnpmHome = path.join(dest, 'node_modules/.bin')
    addPath(pnpmHome)
    exportVariable('PNPM_HOME', pnpmHome)

    // Clean up bootstrap directory
    await rm(bootstrapDir, { recursive: true, force: true }).catch(() => {})
  }
  return exitCode
}

function runCommand(cmd: string, args: string[], opts: { cwd: string }): Promise<number> {
  return new Promise<number>((resolve, reject) => {
    const cp = spawn(cmd, args, {
      cwd: opts.cwd,
      stdio: ['pipe', 'inherit', 'inherit'],
      shell: process.platform === 'win32',
    })
    cp.on('error', reject)
    cp.on('close', resolve)
  })
}

async function readTarget(opts: {
  readonly version?: string | undefined
  readonly packageJsonFile: string
  readonly standalone: boolean
}) {
  const { version, packageJsonFile, standalone } = opts
  const { GITHUB_WORKSPACE } = process.env

  let packageManager

  if (GITHUB_WORKSPACE) {
    try {
      const content = readFileSync(path.join(GITHUB_WORKSPACE, packageJsonFile), 'utf8');
      ({ packageManager } = packageJsonFile.endsWith(".yaml")
        ? parseYaml(content, { merge: true })
        : JSON.parse(content)
      )
    } catch (error: unknown) {
      // Swallow error if package.json doesn't exist in root
      if (!util.types.isNativeError(error) || !('code' in error) || error.code !== 'ENOENT') throw error
    }
  }

  if (version) {
    if (
      typeof packageManager === 'string' &&
      packageManager.startsWith('pnpm@') &&
      packageManager.replace('pnpm@', '') !== version
    ) {
      throw new Error(`Multiple versions of pnpm specified:
  - version ${version} in the GitHub Action config with the key "version"
  - version ${packageManager} in the package.json with the key "packageManager"
Remove one of these versions to avoid version mismatch errors like ERR_PNPM_BAD_PM_VERSION`)
    }

    return `${ standalone ? '@pnpm/exe' : 'pnpm' }@${version}`
  }

  if (!GITHUB_WORKSPACE) {
    throw new Error(`No workspace is found.
If you've intended to let pnpm/action-setup read preferred pnpm version from the "packageManager" field in the package.json file,
please run the actions/checkout before pnpm/action-setup.
Otherwise, please specify the pnpm version in the action configuration.`)
  }

  if (typeof packageManager !== 'string') {
    throw new Error(`No pnpm version is specified.
Please specify it by one of the following ways:
  - in the GitHub Action config with the key "version"
  - in the package.json with the key "packageManager"`)
  }

  if (!packageManager.startsWith('pnpm@')) {
    throw new Error('Invalid packageManager field in package.json')
  }

  if (standalone) {
    return packageManager.replace('pnpm@', '@pnpm/exe@')
  }

  return packageManager
}

export default runSelfInstaller