import os from 'os'
import path, { dirname } from 'path'
import fs from 'fs-extra'
import { NextConfig } from 'next'
import { FileRef } from '../e2e-utils'
import { ChildProcess } from 'child_process'
import { createNextInstall } from '../create-next-install'

type Event = 'stdout' | 'stderr' | 'error' | 'destroy'
export type InstallCommand = string | ((ctx: { dependencies: { [key: string]: string } }) => string)

export type PackageJson = {
  [key: string]: unknown
}
export class NextInstance {
  protected files:
    | FileRef
    | {
        [filename: string]: string | FileRef
      }
  protected nextConfig?: NextConfig
  protected installCommand?: InstallCommand
  protected buildCommand?: string
  protected startCommand?: string
  protected dependencies?: { [name: string]: string }
  protected events: { [eventName: string]: Set<any> }
  public testDir: string
  protected isStopping: boolean
  protected isDestroyed: boolean
  protected childProcess: ChildProcess
  protected _url: string
  protected _parsedUrl: URL
  protected packageJson: PackageJson
  protected packageLockPath?: string
  protected basePath?: string
  protected env?: Record<string, string>
  public forcedPort?: string

  constructor({
    files,
    dependencies,
    nextConfig,
    installCommand,
    buildCommand,
    startCommand,
    packageJson = {},
    packageLockPath,
    env,
  }: {
    files:
      | FileRef
      | {
          [filename: string]: string | FileRef
        }
    dependencies?: {
      [name: string]: string
    }
    packageJson?: PackageJson
    packageLockPath?: string
    nextConfig?: NextConfig
    installCommand?: InstallCommand
    buildCommand?: string
    startCommand?: string
    env?: Record<string, string>
  }) {
    this.files = files
    this.dependencies = dependencies
    this.nextConfig = nextConfig
    this.installCommand = installCommand
    this.buildCommand = buildCommand
    this.startCommand = startCommand
    this.packageJson = packageJson
    this.packageLockPath = packageLockPath
    this.events = {}
    this.isDestroyed = false
    this.isStopping = false
    this.env = env
  }

  protected async createTestDir({ skipInstall = false }: { skipInstall?: boolean } = {}) {
    if (this.isDestroyed) {
      throw new Error('next instance already destroyed')
    }

    const tmpDir = process.env.NEXT_TEST_DIR || (await fs.realpath(os.tmpdir()))
    this.testDir = path.join(tmpDir, `next-test-${Date.now()}-${(Math.random() * 1000) | 0}`)

    const finalDependencies = {
      react: 'latest',
      'react-dom': 'latest',
      ...this.dependencies,
      ...((this.packageJson.dependencies as object | undefined) || {}),
    }

    const plugin = dirname(require.resolve('@netlify/plugin-nextjs/package.json'))

    const pkgScripts = (this.packageJson['scripts'] as {}) || {}
    await fs.ensureDir(this.testDir)

    const finalPackageJson = {
      ...this.packageJson,
      license: 'MIT',
      dependencies: {
        ...finalDependencies,
        '@netlify/plugin-nextjs': `file:${plugin}`,
        next: process.env.NEXT_TEST_VERSION || require('next/package.json').version,
      },
      scripts: {
        build: 'next build',
        ...pkgScripts,
      },
    }

    if (this.files instanceof FileRef) {
      // if a FileRef is passed directly to `files` we copy the
      // entire folder to the test directory
      const stats = await fs.stat(this.files.fsPath)

      if (!stats.isDirectory()) {
        throw new Error(`FileRef passed to "files" in "createNext" is not a directory ${this.files.fsPath}`)
      }
      await fs.copy(this.files.fsPath, this.testDir)
    } else {
      for (const filename of Object.keys(this.files)) {
        const item = this.files[filename]
        const outputFilename = path.join(this.testDir, filename)

        if (typeof item === 'string') {
          await fs.ensureDir(path.dirname(outputFilename))
          await fs.writeFile(outputFilename, item)
        } else {
          await fs.copy(item.fsPath, outputFilename)
        }
      }
    }

    await fs.writeFile(path.join(this.testDir, 'package.json'), JSON.stringify(finalPackageJson, null, 2))

    if (!fs.existsSync(path.join(this.testDir, 'netlify.toml'))) {
      const toml = /* toml */ `
        [build]
        command = "yarn build"
        publish = ".next"
        
        [[plugins]]
        package = "@netlify/plugin-nextjs"
        `

      await fs.writeFile(path.join(this.testDir, 'netlify.toml'), toml)
    }

    let nextConfigFile = Object.keys(this.files).find((file) => file.startsWith('next.config.'))

    if (await fs.pathExists(path.join(this.testDir, 'next.config.js'))) {
      nextConfigFile = 'next.config.js'
    }

    if (nextConfigFile && this.nextConfig) {
      throw new Error(
        `nextConfig provided on "createNext()" and as a file "${nextConfigFile}", use one or the other to continue`,
      )
    }

    if (this.nextConfig || ((global as any).isNextDeploy && !nextConfigFile)) {
      const functions = []

      await fs.writeFile(
        path.join(this.testDir, 'next.config.js'),
        `
        module.exports = ` +
          JSON.stringify(
            {
              ...this.nextConfig,
            } as NextConfig,
            (key, val) => {
              if (typeof val === 'function') {
                functions.push(val.toString().replace(new RegExp(`${val.name}[\\s]{0,}\\(`), 'function('))
                return `__func_${functions.length - 1}`
              }
              return val
            },
            2,
          ).replace(/"__func_[\d]{1,}"/g, function (str) {
            return functions.shift()
          }),
      )
    }

    if ((global as any).isNextDeploy) {
      const fileName = path.join(this.testDir, nextConfigFile || 'next.config.js')
      const content = await fs.readFile(fileName, 'utf8')

      if (content.includes('basePath')) {
        this.basePath = content.match(/['"`]?basePath['"`]?:.*?['"`](.*?)['"`]/)?.[1] || ''
      }

      await fs.writeFile(
        fileName,
        `${content}\n` +
          `
          // alias __NEXT_TEST_MODE for next-deploy as "_" is not a valid
          // env variable during deploy
          if (process.env.NEXT_PRIVATE_TEST_MODE) {
            process.env.__NEXT_TEST_MODE = process.env.NEXT_PRIVATE_TEST_MODE
          }
        `,
      )
    }
    require('console').log(`Test directory created at ${this.testDir}`)
  }

  public async clean() {
    if (this.childProcess) {
      throw new Error(`stop() must be called before cleaning`)
    }

    const keptFiles = ['node_modules', 'package.json', 'yarn.lock']
    for (const file of await fs.readdir(this.testDir)) {
      if (!keptFiles.includes(file)) {
        await fs.remove(path.join(this.testDir, file))
      }
    }
  }

  public async export(): Promise<{ exitCode?: number; cliOutput?: string }> {
    return {}
  }
  public async setup(): Promise<void> {}
  public async start(useDirArg: boolean = false): Promise<void> {}

  public async destroy(): Promise<void> {
    if (this.isDestroyed) {
      throw new Error(`next instance already destroyed`)
    }
    this.isDestroyed = true
    this.emit('destroy', [])

    if (!process.env.NEXT_TEST_SKIP_CLEANUP) {
      await fs.remove(this.testDir)
    }
    require('console').log(`destroyed next instance`)
  }

  public get url() {
    return this._url
  }

  public get appPort() {
    return this._parsedUrl.port
  }

  public get buildId(): string {
    return ''
  }

  public get cliOutput(): string {
    return ''
  }

  // TODO: block these in deploy mode
  public async readFile(filename: string) {
    return fs.readFile(path.join(this.testDir, filename), 'utf8')
  }
  public async patchFile(filename: string, content: string) {
    const outputPath = path.join(this.testDir, filename)
    await fs.ensureDir(path.dirname(outputPath))
    return fs.writeFile(outputPath, content)
  }
  public async renameFile(filename: string, newFilename: string) {
    return fs.rename(path.join(this.testDir, filename), path.join(this.testDir, newFilename))
  }
  public async deleteFile(filename: string) {
    return fs.remove(path.join(this.testDir, filename))
  }

  public on(event: Event, cb: (...args: any[]) => any) {
    if (!this.events[event]) {
      this.events[event] = new Set()
    }
    this.events[event].add(cb)
  }

  public off(event: Event, cb: (...args: any[]) => any) {
    this.events[event]?.delete(cb)
  }

  protected emit(event: Event, args: any[]) {
    this.events[event]?.forEach((cb) => {
      cb(...args)
    })
  }
}