sqldef.rb

# frozen_string_literal: true

require 'etc'
require 'fileutils'
require 'net/http'
require 'rubygems/package'
require 'stringio'
require 'uri'
require 'zlib'
require 'zip'
require_relative 'sqldef/version'

module Sqldef
  GOARCH = {
    'x86_64'  => 'amd64',
    'aarch64' => 'arm64',
    # TODO: add arm and 386
  }
  private_constant :GOARCH

  COMMANDS = %w[
    mysqldef
    psqldef
    sqlite3def
  ]
  private_constant :COMMANDS

  OS_ARCHIVE = {
    'linux' => 'tar.gz',
    'windows' => 'zip',
    'darwin' => 'zip',
  }
  private_constant :OS_ARCHIVE

  @bin = Dir.pwd

  class << self
    attr_accessor :bin

    # @param [String,Symbol] command - mysqldef, psqldef, sqllite3def
    # @param [String] path - Schema export path
    def export(command:, path:, host:, port: nil, user:, password: nil, database:)
      sqldef = download(command)
      schema = IO.popen(
        [
          sqldef,
          "--user=#{user}", *(["--password=#{password}"] if password),
          "--host=#{host}", *(["--port=#{port}"] if port),
          '--export', database,
        ],
        &:read
      )
      raise "Failed to execute '#{sqldef}'" unless $?.success?
      File.write(path, schema)
    end

    # @param [String,Symbol] command - mysqldef, psqldef, sqllite3def
    # @param [String] path - Schema file path
    def dry_run(command:, path:, host:, port: nil, user:, password: nil, database:)
      sqldef = download(command)
      execute(
        sqldef,
        "--user=#{user}", *(["--password=#{password}"] if password),
        "--host=#{host}", *(["--port=#{port}"] if port),
        '--dry-run', database,
        in: path,
      )
    end

    # @param [String,Symbol] command - mysqldef, psqldef, sqllite3def
    # @param [String] path - Schema file path
    def apply(command:, path:, host:, port: nil, user:, password: nil, database:)
      sqldef = download(command)
      execute(
        sqldef,
        "--user=#{user}", *(["--password=#{password}"] if password),
        "--host=#{host}", *(["--port=#{port}"] if port),
        database,
        in: path,
      )
    end

    # @param [String,Symbol] command - mysqldef, psqldef, sqllite3def
    # @return String - command path
    def download(command)
      path = File.join(bin, command = command.to_s)
      return path if File.executable?(path)

      print("Downloading '#{command}' under '#{bin}'... ")
      url = build_url(command)
      resp = get(url, code: 200, max_retries: 4)

      if url.end_with?('.zip')
        Zip::File.open_buffer(resp.body) do |zip|
          unless entry = zip.find_entry(command)
            raise "'#{command}' was not found in the archive"
          end
          File.binwrite(path, zip.read(entry))
        end
      else
        gzip = Zlib::GzipReader.new(StringIO.new(resp.body))
        Gem::Package::TarReader.new(gzip) do |tar|
          unless file = tar.find { |f| f.full_name == command }
            raise "'#{command}' was not found in the archive"
          end
          File.binwrite(path, file.read)
        end
      end

      FileUtils.chmod('+x', path)
      puts 'done.'
      path
    end

    private

    def execute(*cmd, **opts)
      unless system(*cmd, **opts)
        raise "Failed to execute '#{cmd.first.is_a?(Hash) ? cmd[1] : cmd.first}'"
      end
    end

    def build_url(command)
      unless COMMANDS.include?(command)
        raise "Unexpected sqldef command: #{command}" 
      end
      os = Etc.uname.fetch(:sysname).downcase
      archive = OS_ARCHIVE.fetch(os)
      arch = Etc.uname.fetch(:machine)
      goarch = GOARCH.fetch(arch, arch)
      "https://github.com/sqldef/sqldef/releases/latest/download/#{command}_#{os}_#{goarch}.#{archive}"
    end

    # TODO: Retry transient errors
    def get(url, code: nil, max_retries:)
      uri = URI.parse(url)
      resp = Net::HTTP.start(uri.host, uri.port, use_ssl: uri.scheme == 'https') do |http|
        http.get("#{uri.path}?#{uri.query}")
      end
      if resp.is_a?(Net::HTTPRedirection) && max_retries > 0
        # Follow redirects that lead to the current repository (if sqldef/sqldef is moved),
        # Latest, vX.Y.Z, and to the binary
        return get(resp['location'], code: code, max_retries: max_retries - 1)
      elsif code && resp.code != code.to_s
        raise "Expected '#{url}' to return #{code}, but got #{resp.code}: #{resp.body}"
      end
      resp
    end
  end
end