import { dirname, normalize, join } from 'path'
import { Buffer } from 'buffer'
import { createHash } from 'crypto'
import { createReadStream } from 'fs'
import { Readable } from 'stream'
import { spawn } from 'child_process'
import { Logger } from './logger'
import { readFileAsync, writeFileAsync, pathExistsAsync, dequote, isWindows, bound } from './util'
import { NexeOptions, version } from './options'
import { NexeTarget } from './target'
import download = require('download')
import { getLatestGitRelease } from './releases'
import { IncomingMessage } from 'http'

const isBsd = Boolean(~process.platform.indexOf('bsd'))
const make = isWindows ? 'vcbuild.bat' : isBsd ? 'gmake' : 'make'
const configure = isWindows ? 'configure' : './configure'

export interface NexeFile {
  filename: string
  absPath: string
  contents: string
}

export { NexeOptions }

interface NexeHeader {
  resources: { [key: string]: number[] }
  version: string
}

export class NexeCompiler<T extends NexeOptions = NexeOptions> {
  private start = Date.now()
  private env = { ...process.env }
  private compileStep: { modify: Function; log: Function }
  public log = new Logger(this.options.loglevel)
  public src: string
  public files: NexeFile[] = []
  public shims: string[] = []
  public input: string
  public bundledInput?: string
  public targets: NexeTarget[]
  public target: NexeTarget
  public resources: { bundle: Buffer; index: { [key: string]: number[] } } = {
    index: {},
    bundle: Buffer.from('')
  }
  public output = isWindows
    ? `${(this.options.output || this.options.name).replace(/\.exe$/, '')}.exe`
    : `${this.options.output || this.options.name}`

  private nodeSrcBinPath: string
  constructor(public options: T) {
    const { python } = (this.options = options)
    this.targets = options.targets as NexeTarget[]
    this.target = this.targets[0]
    this.src = join(this.options.temp, this.target.version)
    this.nodeSrcBinPath = isWindows
      ? join(this.src, 'Release', 'node.exe')
      : join(this.src, 'out', 'Release', 'node')
    this.log.step('nexe ' + version, 'info')
    if (python) {
      if (isWindows) {
        this.env.PATH = '"' + dequote(normalize(python)) + '";' + this.env.PATH
      } else {
        this.env.PYTHON = python
      }
    }
  }

  @bound
  addResource(file: string, contents: Buffer) {
    const { resources } = this
    resources.index[file] = [resources.bundle.byteLength, contents.byteLength]
    resources.bundle = Buffer.concat([resources.bundle, contents])
  }

  @bound
  async readFileAsync(file: string) {
    this.assertBuild()
    let cachedFile = this.files.find(x => normalize(x.filename) === normalize(file))
    if (!cachedFile) {
      const absPath = join(this.src, file)
      cachedFile = {
        absPath,
        filename: file,
        contents: await readFileAsync(absPath, 'utf-8').catch(x => {
          if (x.code === 'ENOENT') return ''
          throw x
        })
      }
      this.files.push(cachedFile)
    }
    return cachedFile
  }

  @bound
  writeFileAsync(file: string, contents: string | Buffer) {
    this.assertBuild()
    return writeFileAsync(join(this.src, file), contents)
  }

  @bound
  async replaceInFileAsync(file: string, replace: string | RegExp, value: string) {
    const entry = await this.readFileAsync(file)
    entry.contents = entry.contents.replace(replace, value)
  }

  @bound
  async setFileContentsAsync(file: string, contents: string) {
    const entry = await this.readFileAsync(file)
    entry.contents = contents
  }

  quit() {
    const time = Date.now() - this.start
    this.log.write(`Finished in ${time / 1000}s`)
    return this.log.flush()
  }

  assertBuild() {
    if (!this.options.build) {
      throw new Error('This feature is only available with `--build`')
    }
  }

  public getNodeExecutableLocation(target?: NexeTarget) {
    if (target) {
      return join(this.options.temp, target.toString())
    }
    return this.nodeSrcBinPath
  }

  private _runBuildCommandAsync(command: string, args: string[]) {
    return new Promise((resolve, reject) => {
      spawn(command, args, {
        cwd: this.src,
        env: this.env,
        stdio: 'ignore'
      })
        .once('error', reject)
        .once('close', resolve)
    })
  }

  private _configureAsync() {
    return this._runBuildCommandAsync(this.env.PYTHON || 'python', [
      configure,
      ...this.options.configure
    ])
  }

  private async _buildAsync() {
    this.compileStep.log(
      `Configuring node build${this.options.configure.length
        ? ': ' + this.options.configure
        : '...'}`
    )
    await this._configureAsync()
    const buildOptions = this.options.make
    this.compileStep.log(
      `Compiling Node${buildOptions.length ? ' with arguments: ' + buildOptions : '...'}`
    )
    await this._runBuildCommandAsync(make, buildOptions)
    return createReadStream(this.getNodeExecutableLocation())
  }

  private async _fetchPrebuiltBinaryAsync(target: NexeTarget) {
    const downloadOptions: any = {
      headers: {
        'User-Agent': 'nexe (https://www.npmjs.com/package/nexe)'
      }
    }
    const githubRelease = await getLatestGitRelease(downloadOptions)
    const assetName = target.toString()
    const asset = githubRelease.assets.find(x => x.name === assetName)

    if (!asset) {
      throw new Error(`${assetName} not available, create it using the --build flag`)
    }
    const filename = this.getNodeExecutableLocation(target)
    await download(
      asset.browser_download_url,
      dirname(filename),
      downloadOptions
    ).on('response', (res: IncomingMessage) => {
      const total = +res.headers['content-length']!
      let current = 0
      res.on('data', data => {
        current += data.length
        this.compileStep.modify(`Downloading...${(current / total * 100).toFixed()}%`)
      })
    })
    return createReadStream(filename)
  }

  getHeader() {
    const version =
      ['configure', 'vcBuild', 'make'].reduce((a, c) => {
        return (a += (this.options as any)[c]
          .slice()
          .sort()
          .join())
      }, '') + this.options.enableNodeCli
    const header = {
      resources: this.resources.index,
      version: createHash('md5')
        .update(version)
        .digest('hex')
    }
    return `process.__nexe=${JSON.stringify(header)};`
  }

  async compileAsync(target: NexeTarget) {
    const step = (this.compileStep = this.log.step('Compiling result'))
    const build = this.options.build
    const location = this.getNodeExecutableLocation(build ? undefined : target)
    let binary = (await pathExistsAsync(location)) ? createReadStream(location) : null
    if (!build && !binary) {
      step.modify('Fetching prebuilt binary')
      binary = await this._fetchPrebuiltBinaryAsync(target)
    }
    if (!binary) {
      binary = await this._buildAsync()
      step.log('Node binary compiled')
    }
    return this._assembleDeliverable(binary)
  }

  private _assembleDeliverable(binary: NodeJS.ReadableStream) {
    if (this.options.empty) {
      return binary
    }
    const artifact = new Readable({ read() {} })
    binary.on('data', (chunk: Buffer) => {
      artifact.push(chunk)
    })
    binary.on('close', () => {
      const content = [this.shims.join(''), this.input].join(';')
      artifact.push(content)
      artifact.push(this.resources.bundle)
      const lengths = Buffer.from(Array(16))
      lengths.writeDoubleLE(Buffer.byteLength(content), 0)
      lengths.writeDoubleLE(this.resources.bundle.byteLength, 8)
      artifact.push(Buffer.concat([Buffer.from('<nexe~~sentinel>'), lengths]))
      artifact.push(null)
    })
    return artifact
  }
}