#!/usr/bin/env ruby
require "stringio"

def usage
  puts "Usage: #{$0} <kamal_site_repo>"
  exit 1
end

usage if ARGV.size != 1

kamal_site_repo = ARGV[0]

if !File.directory?(kamal_site_repo)
  puts "Error: #{kamal_site_repo} is not a directory"
  exit 1
end

DOCS = {
  "accessory" => "Accessories",
  "alias" => "Aliases",
  "boot" => "Booting",
  "builder" => "Builders",
  "configuration" => "Configuration overview",
  "env" => "Environment variables",
  "logging" => "Logging",
  "proxy" => "Proxy",
  "registry" => "Docker Registry",
  "role" => "Roles",
  "servers" => "Servers",
  "ssh" => "SSH",
  "sshkit" => "SSHKit"
}
DOCS_PATH = "lib/kamal/configuration/docs"

class DocWriter
  attr_reader :from_file, :to_file, :key, :heading, :body, :output, :in_yaml

  def initialize(from_file, to_dir)
    @from_file = from_file
    @key = File.basename(from_file, ".yml")
    @to_file = File.join(to_dir, "#{linkify(DOCS[key])}.md")
    @body = File.readlines(from_file)
    @heading = body.shift.chomp("\n")
    @output = nil
  end

  def write
    puts "Writing #{to_file}"
    generate_markdown
    File.write(to_file, output.string)
  end

  private
    def generate_markdown
      @output = StringIO.new

      generate_header

      place = :in_section

      loop do
        line = body.shift&.chomp("\n")
        break if line.nil?

        case place
        when :new_section, :in_section
          if line.empty?
            output.puts
            place = :new_section
          elsif line =~ /^ *#/
            generate_line(line, heading: place == :new_section)
            place = :in_section
          else
            output.puts
            output.puts "```yaml"
            output.puts line
            place = :in_yaml
          end
        when :in_yaml, :in_empty_line_yaml
          if line =~ /^ *#/
            output.puts "```"
            output.puts
            generate_line(line, heading: place == :in_empty_line_yaml)
            place = :in_section
          elsif line.empty?
            place = :in_empty_line_yaml
          else
            output.puts line
          end
        end
      end

      output.puts "```" if place == :in_yaml
    end

    def generate_header
      output.puts "---"
      output.puts "# This file has been generated from the Kamal source, do not edit directly."
      output.puts "# Find the source of this file at #{DOCS_PATH}/#{key}.yml in the Kamal repository."
      output.puts "title: #{heading[2..-1]}"
      output.puts "---"
      output.puts
      output.puts heading
    end

    def generate_line(line, heading: false)
      line = line.gsub(/^ *#\s?/, "")

      if line =~ /(.*)kamal docs ([a-z]*)(.*)/
        line = "#{$1}[#{DOCS[$2]}](../#{linkify(DOCS[$2])})#{$3}"
      end

      if line =~ /(.*)https:\/\/kamal-deploy.org([a-z\/-]*)(.*)/
        line = "#{$1}[#{titlify($2.split("/").last)}](#{$2})#{$3}"
      end

      if heading
        output.puts "## [#{line}](##{linkify(line)})"
      else
        output.puts line
      end
    end

    def linkify(text)
      if text == "Configuration overview"
        "overview"
      else
        text.downcase.gsub(" ", "-")
      end
    end

    def titlify(text)
      text.capitalize.gsub("-", " ")
    end
end

from_dir = File.join(File.dirname(__FILE__), "../#{DOCS_PATH}")
to_dir = File.join(kamal_site_repo, "docs/configuration")
Dir.glob("#{from_dir}/*") do |from_file|
  DocWriter.new(from_file, to_dir).write
end