module Clayoven::Claytext

# File lib/clayoven/claytext.rb, line 56
def self.fenced_transforms!(paragraphs)
  # For MathJax, exercises, codeblocks, and other fenced content
  Transforms::FENCED.each do |delims, lambda_cb|
    blocks = merge_fenced! paragraphs, delims[0], delims[1]
    blocks.each { |blk| lambda_cb.call blk.block, blk.fc, blk.lc }
  end
end

# File lib/clayoven/claytext.rb, line 86
def self.inline_transforms!(paragraphs)
  paragraphs.each do |p|
    p.replace p
                .gsub(/[<>&]/, HTMLESCAPE_RULES)
                .gsub(/`([^`]+)`/, '<mark>\1</mark>')
                .gsub(/!\{([^\}]+)\}/, '<strong>\1</strong>')
                .gsub(/!_\{([^\}]+)\}/, '<em>\1</em>')
                .gsub(/\[([^\[\]]+)\]\(([^)]+)\)/, '<a href="\2">\1</a>')
                .gsub("\u{23CE}", "<br>")
  end
end

# File lib/clayoven/claytext.rb, line 65
def self.line_transforms!(paragraphs)
  # Preprocess lines ending with ' \\' and insert a special unicode char for conversion to <br>
  paragraphs.each { |p| p.gsub! " \\\\\n", "\u{23CE}" }

  # Now do the all the line transforms, never operating on a line more than once
  Transforms::LINE.each do |regex, lambda_cb|
    paragraphs
      .filter { |p| p.type == :plain and p.split("\n").all? regex }
      .each do |p|
        # Strip the regex before calling the lambda
        match = p.match regex
        p.gsub! regex, ""
        lambda_cb.call p, match
      end
  end
end

# File lib/clayoven/claytext.rb, line 30
def self.merge_fenced!(paragraphs, fregex, lregex)
  mb = Struct.new(:block, :fc, :lc)
  matched_blocks = []
  paragraphs.each_with_index do |p, pidx|
    pmatch = fregex.match p
    next unless pmatch

    paragraphs[pidx..].each_with_index do |q, idx|
      qmatch = lregex.match q
      next unless qmatch

      # Replace paragraph p with all the paragraphs from pidx to pidx + idx,
      # after stripping out the delims.
      # The final result, the "fenced paragraph" sits at pidx.
      p.replace(Util.slice_strip_fences!(paragraphs, pidx, idx + 1))
      matched_blocks << mb.new(p, pmatch, qmatch)

      # The final result is at pidx; throw out all the idx paragraphs, starting at pidx + 1
      paragraphs.slice! pidx + 1, idx
      break
    end
  end
  matched_blocks
end

# File lib/clayoven/claytext.rb, line 102
def self.process(body)
  # Split the body into Paragraphs
  paragraphs = body.split("\n\n").map { |p| Paragraph.new p.rstrip }

  # First, do the fenced transforms on all paragraphs
  fenced_transforms! paragraphs

  # Then, do the line transforms on paragraphs untouched by the fenced transforms
  line_transforms! (paragraphs.filter { |p| p.type == :plain })

  # Finally, do inline transforms on paragraphs untouched by the fenced transforms
  inline_transforms! (
                       paragraphs.reject { |p|
                         %i[codeblock images mathjax].count(p.type).positive?
                       }
                     )

  # Result: paragraphs
  paragraphs
end