# The OSM module provides support functions for OSM.
module OSM
  require "time"
  require "rexml/parsers/sax2parser"
  require "rexml/text"
  require "xml/libxml"

  # The base class for API Errors.
  class APIError < RuntimeError
    def initialize(message = "Generic API Error")
      super message
    end

    def status
      :internal_server_error
    end
  end

  # Raised when access is denied.
  class APIAccessDenied < APIError
    def initialize
      super "Access denied"
    end

    def status
      :forbidden
    end
  end

  # Raised when an API object is not found.
  class APINotFoundError < APIError
    def initialize
      super "Object not found"
    end

    def status
      :not_found
    end
  end

  # Raised when a precondition to an API action fails sanity check.
  class APIPreconditionFailedError < APIError
    def initialize(message = "")
      super "Precondition failed: #{message}"
    end

    def status
      :precondition_failed
    end
  end

  # Raised when to delete an already-deleted object.
  class APIAlreadyDeletedError < APIError
    def initialize(object = "object", object_id = "")
      @object = object
      @object_id = object_id

      super "The #{object} with the id #{object_id} has already been deleted"
    end

    attr_reader :object, :object_id

    def status
      :gone
    end
  end

  # Raised when the user logged in isn't the same as the changeset
  class APIUserChangesetMismatchError < APIError
    def initialize
      super "The user doesn't own that changeset"
    end

    def status
      :conflict
    end
  end

  # Raised when the changeset provided is already closed
  class APIChangesetAlreadyClosedError < APIError
    def initialize(changeset)
      @changeset = changeset

      super "The changeset #{changeset.id} was closed at #{changeset.closed_at}"
    end

    attr_reader :changeset

    def status
      :conflict
    end
  end

  # Raised when the changeset provided is not yet closed
  class APIChangesetNotYetClosedError < APIError
    def initialize(changeset)
      @changeset = changeset

      super "The changeset #{changeset.id} is not yet closed."
    end

    attr_reader :changeset

    def status
      :conflict
    end
  end

  # Raised when a user is already subscribed to the changeset
  class APIChangesetAlreadySubscribedError < APIError
    def initialize(changeset)
      @changeset = changeset

      super "You are already subscribed to changeset #{changeset.id}."
    end

    attr_reader :changeset

    def status
      :conflict
    end
  end

  # Raised when a user is not subscribed to the changeset
  class APIChangesetNotSubscribedError < APIError
    def initialize(changeset)
      @changeset = changeset

      super "You are not subscribed to changeset #{changeset.id}."
    end

    attr_reader :changeset

    def status
      :not_found
    end
  end

  # Raised when a change is expecting a changeset, but the changeset doesn't exist
  class APIChangesetMissingError < APIError
    def initialize
      super "You need to supply a changeset to be able to make a change"
    end

    def status
      :conflict
    end
  end

  # Raised when a diff is uploaded containing many changeset IDs which don't match
  # the changeset ID that the diff was uploaded to.
  class APIChangesetMismatchError < APIError
    def initialize(provided, allowed)
      super "Changeset mismatch: Provided #{provided} but only #{allowed} is allowed"
    end

    def status
      :conflict
    end
  end

  # Raised when a diff upload has an unknown action. You can only have create,
  # modify, or delete
  class APIChangesetActionInvalid < APIError
    def initialize(provided)
      super "Unknown action #{provided}, choices are create, modify, delete"
    end

    def status
      :bad_request
    end
  end

  # Raised when bad XML is encountered which stops things parsing as
  # they should.
  class APIBadXMLError < APIError
    def initialize(model, xml, message = "")
      super "Cannot parse valid #{model} from xml string #{xml}. #{message}"
    end

    def status
      :bad_request
    end
  end

  # Raised when the provided version is not equal to the latest in the db.
  class APIVersionMismatchError < APIError
    def initialize(id, type, provided, latest)
      @id = id
      @type = type
      @provided = provided
      @latest = latest

      super "Version mismatch: Provided #{provided}, server had: #{latest} of #{type} #{id}"
    end

    attr_reader :provided, :latest, :id, :type

    def status
      :conflict
    end
  end

  # raised when a two tags have a duplicate key string in an element.
  # this is now forbidden by the API.
  class APIDuplicateTagsError < APIError
    def initialize(type, id, tag_key)
      @type = type
      @id = id
      @tag_key = tag_key

      super "Element #{type}/#{id} has duplicate tags with key #{tag_key}"
    end

    attr_reader :type, :id, :tag_key

    def status
      :bad_request
    end
  end

  # Raised when a way has more than the configured number of way nodes.
  # This prevents ways from being to long and difficult to work with
  class APITooManyWayNodesError < APIError
    def initialize(id, provided, max)
      super "You tried to add #{provided} nodes to way #{id}, however only #{max} are allowed"

      @id = id
      @provided = provided
      @max = max
    end

    attr_reader :id, :provided, :max

    def status
      :bad_request
    end
  end

  # Raised when a relation has more than the configured number of relation members.
  # This prevents relations from being too complex and difficult to work with
  class APITooManyRelationMembersError < APIError
    def initialize(id, provided, max)
      super "You tried to add #{provided} members to relation #{id}, however only #{max} are allowed"

      @id = id
      @provided = provided
      @max = max
    end

    attr_reader :id, :provided, :max

    def status
      :bad_request
    end
  end

  ##
  # raised when user input couldn't be parsed
  class APIBadUserInput < APIError
    def status
      :bad_request
    end
  end

  ##
  # raised when bounding box is invalid
  class APIBadBoundingBox < APIError
    def status
      :bad_request
    end
  end

  ##
  # raised when an API call is made using a method not supported on that URI
  class APIBadMethodError < APIError
    def initialize(supported_method)
      super "Only method #{supported_method} is supported on this URI"
    end

    def status
      :method_not_allowed
    end
  end

  ##
  # raised when an API call takes too long
  class APITimeoutError < APIError
    def initialize
      super "Request timed out"
    end

    def status
      :request_timeout
    end
  end

  ##
  # raised when someone tries to redact a current version of
  # an element - only historical versions can be redacted.
  class APICannotRedactError < APIError
    def initialize
      super "Cannot redact current version of element, only historical versions may be redacted."
    end

    def status
      :bad_request
    end
  end

  # Raised when the note provided is already closed
  class APINoteAlreadyClosedError < APIError
    def initialize(note)
      @note = note

      super "The note #{note.id} was closed at #{note.closed_at}"
    end

    attr_reader :note

    def status
      :conflict
    end
  end

  # Raised when the note provided is already open
  class APINoteAlreadyOpenError < APIError
    def initialize(note)
      @note = note

      super "The note #{note.id} is already open"
    end

    attr_reader :note

    def status
      :conflict
    end
  end

  # raised when a two preferences have a duplicate key string.
  class APIDuplicatePreferenceError < APIError
    def initialize(key)
      @key = key

      super "Duplicate preferences with key #{key}"
    end

    attr_reader :key

    def status
      :bad_request
    end
  end

  # Helper methods for going to/from mercator and lat/lng.
  class Mercator
    include Math

    # init me with your bounding box and the size of your image
    def initialize(min_lat, min_lon, max_lat, max_lon, width, height)
      xsize = xsheet(max_lon) - xsheet(min_lon)
      ysize = ysheet(max_lat) - ysheet(min_lat)
      xscale = xsize / width
      yscale = ysize / height
      scale = [xscale, yscale].max

      xpad = (width * scale) - xsize
      ypad = (height * scale) - ysize

      @width = width
      @height = height

      @tx = xsheet(min_lon) - (xpad / 2)
      @ty = ysheet(min_lat) - (ypad / 2)

      @bx = xsheet(max_lon) + (xpad / 2)
      @by = ysheet(max_lat) + (ypad / 2)
    end

    # the following two functions will give you the x/y on the entire sheet

    def ysheet(lat)
      log(tan((PI / 4) + (lat * PI / 180 / 2))) / (PI / 180)
    end

    def xsheet(lon)
      lon
    end

    # and these two will give you the right points on your image. all the constants can be reduced to speed things up. FIXME
    # If the bbox has no extent, return the centre of the image to avoid dividing by zero.

    def y(lat)
      return @height / 2 if (@by - @ty).zero?

      @height - ((ysheet(lat) - @ty) / (@by - @ty) * @height)
    end

    def x(lon)
      return @width / 2 if (@bx - @tx).zero?

      ((xsheet(lon) - @tx) / (@bx - @tx) * @width)
    end
  end

  class GreatCircle
    include Math

    # initialise with a base position
    def initialize(lat, lon)
      @lat = lat * PI / 180
      @lon = lon * PI / 180
    end

    # get the distance from the base position to a given position
    def distance(lat, lon)
      lat = lat * PI / 180
      lon = lon * PI / 180
      6372.795 * 2 * asin(sqrt((sin((lat - @lat) / 2)**2) + (cos(@lat) * cos(lat) * (sin((lon - @lon) / 2)**2))))
    end

    # get the worst case bounds for a given radius from the base position
    def bounds(radius)
      latradius = 2 * asin(sqrt(sin(radius / 6372.795 / 2)**2))

      begin
        lonradius = 2 * asin(sqrt((sin(radius / 6372.795 / 2)**2) / (cos(@lat)**2)))
      rescue Errno::EDOM, Math::DomainError
        lonradius = PI
      end

      minlat = [(@lat - latradius) * 180 / PI, -90].max
      maxlat = [(@lat + latradius) * 180 / PI, 90].min
      minlon = [(@lon - lonradius) * 180 / PI, -180].max
      maxlon = [(@lon + lonradius) * 180 / PI, 180].min

      BoundingBox.new(minlon, minlat, maxlon, maxlat)
    end

    # get the SQL to use to calculate distance
    def sql_for_distance(lat_field, lon_field)
      "6372.795 * 2 * asin(sqrt(power(sin((radians(#{lat_field}) - #{@lat}) / 2), 2) + cos(#{@lat}) * cos(radians(#{lat_field})) * power(sin((radians(#{lon_field}) - #{@lon})/2), 2)))"
    end
  end

  class API
    def xml_doc
      doc = XML::Document.new
      doc.encoding = XML::Encoding::UTF_8
      root = XML::Node.new "osm"
      xml_root_attributes.each do |k, v|
        root[k] = v
      end
      doc.root = root
      doc
    end

    def xml_root_attributes
      { "version" => Settings.api_version,
        "generator" => Settings.generator,
        "copyright" => Settings.copyright_owner,
        "attribution" => Settings.attribution_url,
        "license" => Settings.license_url }
    end
  end

  def self.ip_to_country(ip_address)
    ipinfo = maxmind_database.lookup(ip_address) if Settings.key?(:maxmind_database)

    return ipinfo.country.iso_code if ipinfo&.found?

    nil
  end

  def self.ip_location(ip_address)
    code = OSM.ip_to_country(ip_address)

    if code && country = Country.find(code)
      return { :minlon => country.min_lon, :minlat => country.min_lat, :maxlon => country.max_lon, :maxlat => country.max_lat }
    end

    nil
  end

  # Parse a float, raising a specified exception on failure
  def self.parse_float(str, klass, *args)
    Float(str)
  rescue StandardError
    raise klass.new(*args)
  end

  # Construct a random token of a given length
  def self.make_token(length = 30)
    chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    token = ""

    length.times do
      token += chars[(rand * chars.length).to_i].chr
    end

    token
  end

  # Return an SQL fragment to select a given area of the globe
  def self.sql_for_area(bbox, prefix = nil)
    tilesql = QuadTile.sql_for_area(bbox, prefix)
    bbox = bbox.to_scaled

    "#{tilesql} AND #{prefix}latitude BETWEEN #{bbox.min_lat} AND #{bbox.max_lat} " \
      "AND #{prefix}longitude BETWEEN #{bbox.min_lon} AND #{bbox.max_lon}"
  end

  # Return the terms and conditions text for a given country
  def self.legal_text_for_country(country_code)
    file_name = Rails.root.join("config", "legales", "#{country_code}.yml")
    file_name = Rails.root.join("config", "legales", "#{Settings.default_legale}.yml") unless File.exist? file_name
    YAML.load_file(file_name).transform_values!(&:html_safe)
  end

  # Return the HTTP client to use
  def self.http_client
    @http_client ||= Faraday.new(:request => { :timeout => 15 })
  end

  # Return the MaxMindDB database handle
  def self.maxmind_database
    @maxmind_database ||= MaxMindDB.new(Settings.maxmind_database) if Settings.key?(:maxmind_database)
  end
end