#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

require 'liquid'
require 'rouge'

module Jekyll
 class IncludeExampleTag < Liquid::Tag

 def initialize(tag_name, markup, tokens)
 @markup = markup
 super
 end

 def render(context)
 site = context.registers[:site]
 config_dir = '../examples/src/main'
 @code_dir = File.join(site.source, config_dir)

 clean_markup = @markup.strip

 parts = clean_markup.strip.split(' ')
 if parts.length > 1 then
 @snippet_label = ':' + parts[0]
 snippet_file = parts[1]
 else
 @snippet_label = ''
 snippet_file = parts[0]
 end

 @file = File.join(@code_dir, snippet_file)
 @lang = snippet_file.split('.').last

 begin
 code = File.open(@file).read.encode("UTF-8")
 rescue => e
 # We need to explicitly exit on exceptions here because Jekyll will silently swallow
 # them, leading to silent build failures (see https://github.com/jekyll/jekyll/issues/5104)
 puts(e)
 puts(e.backtrace)
 exit 1
 end
 code = select_lines(code).strip

 formatter = Rouge::Formatters::HTMLPygments.new(Rouge::Formatters::HTML.new)
 lexer = Rouge::Lexer.find(@lang)
 rendered_code = formatter.format(lexer.lex(code))

 hint = "<div><small>Find full example code at " \
 "\"examples/src/main/#{snippet_file}\" in the Spark repo.</small></div>"

 rendered_code + hint
 end

 # Trim the code block so as to have the same indentation, regardless of their positions in the
 # code file.
 def trim_codeblock(lines)
 # Select the minimum indentation of the current code block.
 min_start_spaces = lines
 .select { |l| l.strip.size !=0 }
 .map { |l| l[/\A */].size }
 .min

 lines.map { |l| l.strip.size == 0 ? l : l[min_start_spaces .. -1] }
 end

 # Select lines according to labels in code. Currently we use "$example on$" and "$example off$"
 # as labels. Note that code blocks identified by the labels should not overlap.
 def select_lines(code)
 lines = code.each_line.to_a

 # Select the array of start labels from code.
 startIndices = lines
 .each_with_index
 .select { |l, i| l.include? "$example on#{@snippet_label}$" }
 .map { |l, i| i }

 # Select the array of end labels from code.
 endIndices = lines
 .each_with_index
 .select { |l, i| l.include? "$example off#{@snippet_label}$" }
 .map { |l, i| i }

 raise "Start indices amount is not equal to end indices amount, see #{@file}." \
 unless startIndices.size == endIndices.size

 raise "No code is selected by include_example, see #{@file}." \
 if startIndices.size == 0

 # Select and join code blocks together, with a space line between each of two continuous
 # blocks.
 lastIndex = -1
 result = ""
 startIndices.zip(endIndices).each do |start, endline|
 raise "Overlapping between two example code blocks are not allowed, see #{@file}." \
 if start <= lastIndex
 raise "$example on$ should not be in the same line with $example off,ドル see #{@file}." \
 if start == endline
 lastIndex = endline
 range = Range.new(start + 1, endline - 1)
 trimmed = trim_codeblock(lines[range])
 # Filter out possible example tags of overlapped labels.
 tags_filtered = trimmed.select { |l| !l.include? '$example ' }
 result += tags_filtered.join
 result += "\n"
 end
 result
 end
 end
end

Liquid::Template.register_tag('include_example', Jekyll::IncludeExampleTag)