const { flatten } = require("lodash")
const { cloneDeep } = require("lodash/fp")

const PermissionLevels = {
  READ: "read",
  WRITE: "write",
  EXECUTE: "execute",
  ADMIN: "admin",
}

// these are the global types, that govern the underlying default behaviour
const PermissionTypes = {
  TABLE: "table",
  USER: "user",
  AUTOMATION: "automation",
  WEBHOOK: "webhook",
  BUILDER: "builder",
  VIEW: "view",
  QUERY: "query",
}

function Permission(type, level) {
  this.level = level
  this.type = type
}

function levelToNumber(perm) {
  switch (perm) {
    // not everything has execute privileges
    case PermissionLevels.EXECUTE:
      return 0
    case PermissionLevels.READ:
      return 1
    case PermissionLevels.WRITE:
      return 2
    case PermissionLevels.ADMIN:
      return 3
    default:
      return -1
  }
}

/**
 * Given the specified permission level for the user return the levels they are allowed to carry out.
 * @param {string} userPermLevel The permission level of the user.
 * @return {string[]} All the permission levels this user is allowed to carry out.
 */
function getAllowedLevels(userPermLevel) {
  switch (userPermLevel) {
    case PermissionLevels.EXECUTE:
      return [PermissionLevels.EXECUTE]
    case PermissionLevels.READ:
      return [PermissionLevels.EXECUTE, PermissionLevels.READ]
    case PermissionLevels.WRITE:
    case PermissionLevels.ADMIN:
      return [
        PermissionLevels.READ,
        PermissionLevels.WRITE,
        PermissionLevels.EXECUTE,
      ]
    default:
      return []
  }
}

exports.BUILTIN_PERMISSION_IDS = {
  PUBLIC: "public",
  READ_ONLY: "read_only",
  WRITE: "write",
  ADMIN: "admin",
  POWER: "power",
}

const BUILTIN_PERMISSIONS = {
  PUBLIC: {
    _id: exports.BUILTIN_PERMISSION_IDS.PUBLIC,
    name: "Public",
    permissions: [
      new Permission(PermissionTypes.WEBHOOK, PermissionLevels.EXECUTE),
    ],
  },
  READ_ONLY: {
    _id: exports.BUILTIN_PERMISSION_IDS.READ_ONLY,
    name: "Read only",
    permissions: [
      new Permission(PermissionTypes.QUERY, PermissionLevels.READ),
      new Permission(PermissionTypes.TABLE, PermissionLevels.READ),
      new Permission(PermissionTypes.VIEW, PermissionLevels.READ),
    ],
  },
  WRITE: {
    _id: exports.BUILTIN_PERMISSION_IDS.WRITE,
    name: "Read/Write",
    permissions: [
      new Permission(PermissionTypes.QUERY, PermissionLevels.WRITE),
      new Permission(PermissionTypes.TABLE, PermissionLevels.WRITE),
      new Permission(PermissionTypes.VIEW, PermissionLevels.READ),
    ],
  },
  POWER: {
    _id: exports.BUILTIN_PERMISSION_IDS.POWER,
    name: "Power",
    permissions: [
      new Permission(PermissionTypes.TABLE, PermissionLevels.WRITE),
      new Permission(PermissionTypes.USER, PermissionLevels.READ),
      new Permission(PermissionTypes.AUTOMATION, PermissionLevels.EXECUTE),
      new Permission(PermissionTypes.VIEW, PermissionLevels.READ),
      new Permission(PermissionTypes.WEBHOOK, PermissionLevels.READ),
    ],
  },
  ADMIN: {
    _id: exports.BUILTIN_PERMISSION_IDS.ADMIN,
    name: "Admin",
    permissions: [
      new Permission(PermissionTypes.TABLE, PermissionLevels.ADMIN),
      new Permission(PermissionTypes.USER, PermissionLevels.ADMIN),
      new Permission(PermissionTypes.AUTOMATION, PermissionLevels.ADMIN),
      new Permission(PermissionTypes.VIEW, PermissionLevels.ADMIN),
      new Permission(PermissionTypes.WEBHOOK, PermissionLevels.READ),
      new Permission(PermissionTypes.QUERY, PermissionLevels.ADMIN),
    ],
  },
}

exports.getBuiltinPermissions = () => {
  return cloneDeep(BUILTIN_PERMISSIONS)
}

exports.getBuiltinPermissionByID = id => {
  const perms = Object.values(BUILTIN_PERMISSIONS)
  return perms.find(perm => perm._id === id)
}

exports.doesHaveResourcePermission = (
  permissions,
  permLevel,
  { resourceId, subResourceId }
) => {
  // set foundSub to not subResourceId, incase there is no subResource
  let foundMain = false,
    foundSub = !subResourceId
  for (let [resource, level] of Object.entries(permissions)) {
    const levels = getAllowedLevels(level)
    if (resource === resourceId && levels.indexOf(permLevel) !== -1) {
      foundMain = true
    }
    if (
      subResourceId &&
      resource === subResourceId &&
      levels.indexOf(permLevel) !== -1
    ) {
      foundSub = true
    }
    // this will escape if foundMain only when no sub resource
    if (foundMain && foundSub) {
      break
    }
  }
  return foundMain && foundSub
}

exports.doesHaveBasePermission = (permType, permLevel, permissionIds) => {
  const builtins = Object.values(BUILTIN_PERMISSIONS)
  let permissions = flatten(
    builtins
      .filter(builtin => permissionIds.indexOf(builtin._id) !== -1)
      .map(builtin => builtin.permissions)
  )
  for (let permission of permissions) {
    if (
      permission.type === permType &&
      getAllowedLevels(permission.level).indexOf(permLevel) !== -1
    ) {
      return true
    }
  }
  return false
}

exports.higherPermission = (perm1, perm2) => {
  return levelToNumber(perm1) > levelToNumber(perm2) ? perm1 : perm2
}

exports.isPermissionLevelHigherThanRead = level => {
  return levelToNumber(level) > 1
}

// utility as a lot of things need simply the builder permission
exports.BUILDER = PermissionTypes.BUILDER
exports.PermissionTypes = PermissionTypes
exports.PermissionLevels = PermissionLevels