'use strict'

const fs = require('./wrapped-fs')
const path = require('path')
const tmp = require('tmp-promise')
const UINT64 = require('cuint').UINT64

const UINT32_MAX = 4294967295

class Filesystem {
  constructor (src) {
    this.src = path.resolve(src)
    this.header = { files: {} }
    this.offset = UINT64(0)
  }

  searchNodeFromDirectory (p) {
    let json = this.header
    const dirs = p.split(path.sep)
    for (const dir of dirs) {
      if (dir !== '.') {
        json = json.files[dir]
      }
    }
    return json
  }

  searchNodeFromPath (p) {
    p = path.relative(this.src, p)
    if (!p) { return this.header }
    const name = path.basename(p)
    const node = this.searchNodeFromDirectory(path.dirname(p))
    if (node.files == null) {
      node.files = {}
    }
    if (node.files[name] == null) {
      node.files[name] = {}
    }
    return node.files[name]
  }

  insertDirectory (p, shouldUnpack) {
    const node = this.searchNodeFromPath(p)
    if (shouldUnpack) {
      node.unpacked = shouldUnpack
    }
    node.files = {}
    return node.files
  }

  async insertFile (p, shouldUnpack, file, options) {
    const dirNode = this.searchNodeFromPath(path.dirname(p))
    const node = this.searchNodeFromPath(p)
    if (shouldUnpack || dirNode.unpacked) {
      node.size = file.stat.size
      node.unpacked = true
      return Promise.resolve()
    }

    const handler = (resolve, reject) => {
      const size = file.transformed ? file.transformed.stat.size : file.stat.size

      // JavaScript can not precisely present integers >= UINT32_MAX.
      if (size > UINT32_MAX) {
        const error = new Error(`${p}: file size can not be larger than 4.2GB`)
        if (reject) {
          return reject(error)
        } else {
          throw error
        }
      }

      node.size = size
      node.offset = this.offset.toString()
      if (process.platform !== 'win32' && (file.stat.mode & 0o100)) {
        node.executable = true
      }
      this.offset.add(UINT64(size))

      return resolve ? resolve() : Promise.resolve()
    }

    const transformed = options.transform && options.transform(p)
    if (transformed) {
      const tmpfile = await tmp.file()
      return new Promise((resolve, reject) => {
        const out = fs.createWriteStream(tmpfile.path)
        const stream = fs.createReadStream(p)

        stream.pipe(transformed).pipe(out)
        return out.on('close', async () => {
          file.transformed = {
            path: tmpfile.path,
            stat: await fs.lstat(tmpfile.path)
          }
          return handler(resolve, reject)
        })
      })
    } else {
      return handler()
    }
  }

  insertLink (p) {
    const link = path.relative(fs.realpathSync(this.src), fs.realpathSync(p))
    if (link.substr(0, 2) === '..') {
      throw new Error(`${p}: file links out of the package`)
    }
    const node = this.searchNodeFromPath(p)
    node.link = link
    return link
  }

  listFiles (options) {
    const files = []

    const fillFilesFromMetadata = function (basePath, metadata) {
      if (!metadata.files) {
        return
      }

      for (const [childPath, childMetadata] of Object.entries(metadata.files)) {
        const fullPath = path.join(basePath, childPath)
        const packState = childMetadata.unpacked ? 'unpack' : 'pack  '
        files.push((options && options.isPack) ? `${packState} : ${fullPath}` : fullPath)
        fillFilesFromMetadata(fullPath, childMetadata)
      }
    }

    fillFilesFromMetadata('/', this.header)
    return files
  }

  getNode (p) {
    const node = this.searchNodeFromDirectory(path.dirname(p))
    const name = path.basename(p)
    if (name) {
      return node.files[name]
    } else {
      return node
    }
  }

  getFile (p, followLinks) {
    followLinks = typeof followLinks === 'undefined' ? true : followLinks
    const info = this.getNode(p)

    // if followLinks is false we don't resolve symlinks
    if (info.link && followLinks) {
      return this.getFile(info.link)
    } else {
      return info
    }
  }
}

module.exports = Filesystem