require "json"
require "set"
require "optparse"
require "fileutils"

# For target_dir, use absolute paths because when invoking Agda, we'll be
# using chdir.
root_path = "code"
target_dir = File.expand_path "code"
data_file = "data/submodules.json"
OptionParser.new do |opts|
  opts.banner = "Usage: build-agda-html.rb [options]"

  opts.on("--root-path=PATH", "Search for Agda project folders in the given location") do |f|
    root_path = f
  end
  opts.on("--target-dir=PATH", "Generate HTML files into the given directory") do |f|
    target_dir = File.expand_path f
  end
  opts.on("--data-file=FILE", "Specify the submodules.json that encodes nested submodule structure") do |f|
    data_file = f
  end
end.parse!
files = ARGV

code_paths = Dir.entries(root_path).select do |f|
  File.directory?(File.join(root_path, f)) and f != '.' and f != '..'
end.to_set
code_paths += JSON.parse(File.read(data_file)).keys if File.exists? data_file
# Extending code_paths from submodules.json means that nested Agda modules
# have their root dir correctly set.

max_path = ->(path) {
  code_paths.max_by do |code_path|
    count = 0
    path.chars.zip(code_path.chars) do |c1, c2|
      break unless c1 == c2
      count += 1
    end

    next count
  end
}

files_for_paths = {}
Dir.glob("**/*.agda", base: root_path) do |agda_file|
  best_path = max_path.call(agda_file)
  files_for_path = files_for_paths.fetch(best_path) do
    files_for_paths[best_path] = []
  end

  files_for_path << agda_file[best_path.length + File::SEPARATOR.length..-1]
end

original_wd = Dir.getwd
files_for_paths.each do |path, files|
  Dir.chdir(original_wd)
  Dir.chdir(File.join(root_path, path))
  html_dir = File.join [target_dir, path, "html"]
  FileUtils.mkdir_p html_dir

  files.each do |file|
    command = "#{ARGV[0]} --local-interfaces #{file} --html --html-dir=#{html_dir}"
    puts command
    puts `#{command}`

    # Allow some programs to fail (e.g., IO.agda in SPA without --guardedness)
    # fail unless $? == 0
  end
end