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Issue #31: Add sample delegates.rb file.
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alxp committed Sep 15, 2023
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##
# Sample Ruby delegate script containing stubs and documentation for all
# available delegate methods. See the user manual for more information.
#
# The application will create an instance of this class early in the request
# cycle and dispose of it at the end of the request cycle. Instances don't need
# to be thread-safe, but sharing information across instances (requests)
# **does** need to be done thread-safely.
#
# This version of the script works with Cantaloupe version 4, and not earlier
# versions. Likewise, earlier versions of the script are not compatible with
# Cantaloupe 4.
#
class CustomDelegate

##
# Attribute for the request context, which is a hash containing information
# about the current request.
#
# This attribute will be set by the server before any other methods are
# called. Methods can access its keys like:
#
# ```
# identifier = context['identifier']
# ```
#
# The hash will contain the following keys in response to all requests:
#
# * `client_ip` [String] Client IP address.
# * `cookies` [Hash<String,String>] Hash of cookie name-value pairs.
# * `identifier` [String] Image identifier.
# * `request_headers` [Hash<String,String>] Hash of header name-value pairs.
# * `request_uri` [String] Public request URI.
# * `scale_constraint` [Array<Integer>] Two-element array with scale
# constraint numerator at position 0 and denominator at
# position 1.
#
# It will contain the following additional string keys in response to image
# requests:
#
# * `full_size` [Hash<String,Integer>] Hash with `width` and `height`
# keys corresponding to the pixel dimensions of the
# source image.
# * `operations` [Array<Hash<String,Object>>] Array of operations in
# order of application. Only operations that are not
# no-ops will be included. Every hash contains a `class`
# key corresponding to the operation class name, which
# will be one of the `e.i.l.c.operation.Operation`
# implementations.
# * `output_format` [String] Output format media (MIME) type.
# * `resulting_size` [Hash<String,Integer>] Hash with `width` and `height`
# keys corresponding to the pixel dimensions of the
# resulting image after all operations have been applied.
#
# @return [Hash] Request context.
#
attr_accessor :context

##
# Returns authorization status for the current request. Will be called upon
# all requests to all public endpoints.
#
# Implementations should assume that the underlying resource is available,
# and not try to check for it.
#
# Possible return values:
#
# 1. Boolean true/false, indicating whether the request is fully authorized
# or not. If false, the client will receive a 403 Forbidden response.
# 2. Hash with a `status_code` key.
# a. If it corresponds to an integer from 200-299, the request is
# authorized.
# b. If it corresponds to an integer from 300-399:
# i. If the hash also contains a `location` key corresponding to a
# URI string, the request will be redirected to that URI using
# that code.
# ii. If the hash also contains `scale_numerator` and
# `scale_denominator` keys, the request will be
# redirected using that code to a virtual reduced-scale version of
# the source image.
# c. If it corresponds to 401, the hash must include a `challenge` key
# corresponding to a WWW-Authenticate header value.
#
# @param options [Hash] Empty hash.
# @return [Boolean,Hash<String,Object>] See above.
#
def authorize(options = {})
true
end

##
# Used to add additional keys to an information JSON response. See the
# [Image API specification](http://iiif.io/api/image/2.1/#image-information).
#
# @param options [Hash] Empty hash.
# @return [Hash] Hash that will be merged into an IIIF Image API 2.x
# information response. Return an empty hash to add nothing.
#
def extra_iiif2_information_response_keys(options = {})
=begin
Example:
{
'attribution' => 'Copyright My Great Organization. All rights '\
'reserved.',
'license' => 'http://example.org/license.html',
'logo' => 'http://example.org/logo.png',
'service' => {
'@context' => 'http://iiif.io/api/annex/services/physdim/1/context.json',
'profile' => 'http://iiif.io/api/annex/services/physdim',
'physicalScale' => 0.0025,
'physicalUnits' => 'in'
}
}
=end
{}
end

##
# Tells the server which source to use for the given identifier.
#
# @param options [Hash] Empty hash.
# @return [String] Source name.
#
def source(options = {})
end

##
# N.B.: this method should not try to perform authorization. `authorize()`
# should be used instead.
#
# @param options [Hash] Empty hash.
# @return [String,nil] Blob key of the image corresponding to the given
# identifier, or nil if not found.
#
def azurestoragesource_blob_key(options = {})
end

##
# N.B.: this method should not try to perform authorization. `authorize()`
# should be used instead.
#
# @param options [Hash] Empty hash.
# @return [String,nil] Absolute pathname of the image corresponding to the
# given identifier, or nil if not found.
#
def filesystemsource_pathname(options = {})
end

##
# Returns one of the following:
#
# 1. String URI
# 2. Hash with the following keys:
# * `uri` [String] (required)
# * `username` [String] For HTTP Basic authentication (optional).
# * `secret` [String] For HTTP Basic authentication (optional).
# * `headers` [Hash<String,String>] Hash of request headers (optional).
# 3. nil if not found.
#
# N.B.: this method should not try to perform authorization. `authorize()`
# should be used instead.
#
# @param options [Hash] Empty hash.
# @return See above.
#
def httpsource_resource_info(options = {})
return { "uri" => context['identifier'], "headers" => { "Authorization" => context['request_headers']['authorization'] } }
end

##
# N.B.: this method should not try to perform authorization. `authorize()`
# should be used instead.
#
# @param options [Hash] Empty hash.
# @return [String] Identifier of the image corresponding to the given
# identifier in the database.
#
def jdbcsource_database_identifier(options = {})
end

##
# Returns either the media (MIME) type of an image, or an SQL statement that
# can be used to retrieve it, if it is stored in the database. In the latter
# case, the "SELECT" and "FROM" clauses should be in uppercase in order to
# be autodetected. If nil is returned, the media type will be inferred some
# other way, such as by identifier extension or magic bytes.
#
# @param options [Hash] Empty hash.
# @return [String, nil]
#
def jdbcsource_media_type(options = {})
end

##
# @param options [Hash] Empty hash.
# @return [String] SQL statement that selects the BLOB corresponding to the
# value returned by `jdbcsource_database_identifier()`.
#
def jdbcsource_lookup_sql(options = {})
end

##
# N.B.: this method should not try to perform authorization. `authorize()`
# should be used instead.
#
# @param options [Hash] Empty hash.
# @return [Hash<String,Object>,nil] Hash containing `bucket` and `key` keys;
# or nil if not found.
#
def s3source_object_info(options = {})
end

##
# Tells the server what overlay, if any, to apply to an image in response
# to a request. Will be called upon all image requests to any endpoint if
# overlays are enabled and the overlay strategy is set to `ScriptStrategy`
# in the application configuration.
#
# N.B.: When a string overlay is too large or long to fit entirely within
# the image, it won't be drawn. Consider breaking long strings with LFs (\n).
#
# @param options [Hash] Empty hash.
# @return [Hash<String,String>,nil] For image overlays, a hash with `image`,
# `position`, and `inset` keys. For string overlays, a hash with
# `background_color`, `color`, `font`, `font_min_size`, `font_size`,
# `font_weight`, `glyph_spacing`,`inset`, `position`, `string`,
# `stroke_color`, and `stroke_width` keys.
# Return nil for no overlay.
#
def overlay(options = {})
puts "overlay"
end

##
# Tells the server what regions of an image to redact in response to a
# particular request. Will be called upon all image requests to any endpoint
# if redactions are enabled in the application configuration.
#
# @param options [Hash] Empty hash.
# @return [Array<Hash<String,Integer>>] Array of hashes, each with `x`, `y`,
# `width`, and `height` keys; or an empty array if no redactions are
# to be applied.
#
def redactions(options = {})
puts "redactions"
[]
end

end

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