import gm from 'gm'
import { URL } from 'url'
import path from 'path'
import crypto from 'crypto'
import { v4 as uuid } from 'uuid'

import { downloadURL } from '../../scripts/http'

const fs = require('fs-extra')

const gravatar = 'https://www.gravatar.com/avatar/'

const uploads = path.join(__dirname, '../../', 'usercontent')
const images = path.join(uploads, 'images')
const maxFileSize = 1000000
export const imageTypes = {
  'image/png': '.png',
  'image/jpg': '.jpg',
  'image/jpeg': '.jpeg'
}

function decodeBase64Image (dataString) {
  const matches = dataString.match(/^data:([A-Za-z-+/]+);base64,(.+)$/)
  const response = {}

  if (matches.length !== 3) {
    return null
  }

  response.type = matches[1]
  response.data = Buffer.from(matches[2], 'base64')

  return response
}

function saneFields (fields) {
  const out = {}

  for (const i in fields) {
    const entry = fields[i]
    if (typeof entry === 'object' && entry.length === 1 && !isNaN(parseInt(entry[0]))) {
      out[i] = parseInt(entry[0])
    }
  }

  return out
}

async function bailOut (file, error) {
  await fs.unlink(file)
  throw new Error(error)
}

export async function imageBase64 (baseObj) {
  if (!baseObj) return null
  const imgData = decodeBase64Image(baseObj)

  if (!imgData) return null
  if (!imageTypes[imgData.type]) return null

  let imageName = 'base64-' + uuid()
  const ext = imageTypes[imgData.type] || '.png'

  imageName += ext

  const fpath = path.join(images, imageName)

  try {
    await fs.writeFile(fpath, imgData.data)
  } catch (e) {
    console.error(e)
    return null
  }

  return { file: fpath }
}

export function gravatarURL (email) {
  const sum = crypto.createHash('md5').update(email).digest('hex')
  return gravatar + sum + '.jpg'
}

export async function downloadImage (imgUrl, designation) {
  if (!imgUrl) return null
  if (!designation) designation = 'download'

  let imageName = designation + '-' + uuid()
  const uridata = new URL(imgUrl)
  const pathdata = path.parse(uridata.href)

  imageName += pathdata.ext || '.png'

  try {
    await downloadURL(imgUrl, path.join(images, imageName))
  } catch (e) {
    return null
  }

  return imageName
}

export async function uploadImage (identifier, fields, files) {
  if (!files.image) throw new Error('No image file')

  let file = files.image[0]
  if (file.size > maxFileSize) return bailOut(file.path, 'Image is too large! 1 MB max')

  fields = saneFields(fields)

  // Get file info, generate a file name
  const fileHash = uuid()
  const contentType = file.headers['content-type']
  if (!contentType) return bailOut(file.path, 'Invalid or missing content-type header')

  file = file.path

  // Make sure content type is allowed
  let match = false
  for (const i in imageTypes) {
    if (i === contentType) {
      match = true
      break
    }
  }
  if (!match) return bailOut(file, 'Invalid image type. Only PNG, JPG and JPEG files are allowed.')
  const extension = imageTypes[contentType]
  const fileName = identifier + '-' + fileHash + extension

  // Check for cropping
  if (fields.x == null || fields.y == null || fields.width == null || fields.height == null) {
    return bailOut(file, 'Images can only be cropped on the server side due to security reasons.')
  }

  if (fields.x < 0 || fields.y < 0 || fields.x > fields.width + fields.x || fields.y > fields.height + fields.y) {
    return bailOut(file, 'Impossible crop.')
  }

  // Check 1 : 1 aspect ratio
  if (Math.floor(fields.width / fields.height) !== 1) {
    return bailOut(file, 'Avatars can only have an aspect ratio of 1:1')
  }

  // Upscaling is not allowed
  if ((fields.scaleX != null && fields.scaleX > 1) || (fields.scaleY != null && fields.scaleY > 1)) {
    return bailOut(file, 'Image upscaling is not allowed.')
  }

  if (fields.scaleX != null) {
    fields.x *= fields.scaleX
    fields.width *= fields.scaleX
  }

  if (fields.scaleY != null) {
    fields.y *= fields.scaleY
    fields.height *= fields.scaleY
  }

  // Crop
  try {
    await new Promise(function (resolve, reject) {
      gm(file)
        .crop(fields.width, fields.height, fields.x, fields.y)
        .write(path.join(images, fileName), (err) => {
          if (err) return reject(err)
          resolve(fileName)
        })
    })

    await fs.unlink(file)
  } catch (e) {
    console.error(e)
    return bailOut(file, 'An error occured while cropping.')
  }

  return { file: fileName }
}