hometown/app/lib/webhooks/payload_renderer.rb

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# frozen_string_literal: true
class Webhooks::PayloadRenderer
class DocumentTraverser
INT_REGEX = /[0-9]+/
def initialize(document)
@document = document.with_indifferent_access
end
def get(path)
value = @document.dig(*parse_path(path))
string = Oj.dump(value)
# We want to make sure people can use the variable inside
# other strings, so it can't be wrapped in quotes.
if value.is_a?(String)
string[1...-1]
else
string
end
end
private
def parse_path(path)
path.split('.').filter_map do |segment|
if segment.match(INT_REGEX)
segment.to_i
else
segment.presence
end
end
end
end
class TemplateParser < Parslet::Parser
rule(:dot) { str('.') }
rule(:digit) { match('[0-9]') }
rule(:property_name) { match('[a-z_]').repeat(1) }
rule(:array_index) { digit.repeat(1) }
rule(:segment) { (property_name | array_index) }
rule(:path) { property_name >> (dot >> segment).repeat }
rule(:variable) { (str('}}').absent? >> path).repeat.as(:variable) }
rule(:expression) { str('{{') >> variable >> str('}}') }
rule(:text) { (str('{{').absent? >> any).repeat(1) }
rule(:text_with_expressions) { (text.as(:text) | expression).repeat.as(:text) }
root(:text_with_expressions)
end
EXPRESSION_REGEXP = /
\{\{
[a-z_]+
(\.
([a-z_]+|[0-9]+)
)*
\}\}
/iox
def initialize(json)
@document = DocumentTraverser.new(Oj.load(json))
end
def render(template)
template.gsub(EXPRESSION_REGEXP) { |match| @document.get(match[2...-2]) }
end
end