#!/usr/bin/env ruby -w
require 'serialport'
require 'uri'

class EspyClient
  attr_accessor :socket

  SHORT_DELAY = 0.3
  LONG_DELAY = 0.3
  GOOD_STATUS_CODES = ["OK","ready","Linked","Unlink"]
  BAD_STATUS_CODES = ["ERROR", "link is not"]
  ALL_STATUS_CODES = GOOD_STATUS_CODES + BAD_STATUS_CODES

  def initialize(port_name, port_options={}, read_timeout=15)
    self.socket = SerialPort.new port_name, port_options
    self.socket.read_timeout = read_timeout
    puts "ESP8266 Client initialised for : #{port_name}"
    puts "            connection options : #{socket.modem_params.inspect}"
    puts "                       signals : #{socket.signals.inspect}"
    puts "Waiting to warm up the connection.."
    sleep(LONG_DELAY)
    clear
  rescue Errno::ENOENT
    self.socket = nil
    puts "ERROR: Seems like that port is not available"
  end

  # Command:
  def status(*args)
    tx_with_echo("AT") && tx_with_echo("AT+GMR") && tx_with_echo("AT+CWMODE?") && tx_with_echo("AT+CWJAP?") && tx_with_echo("AT+CIFSR")
  end

  def reset(*args)
    tx_with_echo("AT+RST")
  end

  def ls(*args)
    tx_with_echo("AT+CWLAP")
  end

  def join(ssid,password)
    tx_with_echo(%{AT+CWJAP="#{ssid}","#{password}"})
  end

  def get(url)
    uri = URI.parse(url)
    get_request = "GET #{uri.path} HTTP/1.1" << "\r\n"
    get_request << "Host: #{uri.host}" << "\r\n"
    get_request << "User-Agent: EspyClient/0.9.2.4" << "\r\n"
    get_request << "Accept: */*" << "\r\n"

    if tx_with_echo(%{AT+CIPSTART="TCP","#{uri.host}",#{uri.port}})
      # CIPSEND is a little different - it returns to a > prompt
      socket.write %{AT+CIPSEND=#{get_request.length + 2}\r\n}
      sleep(SHORT_DELAY)
      begin
        print socket.getc
      end until socket.eof?
      tx_with_echo(get_request, false)
    end
    tx_with_echo("AT+CIPCLOSE")
  end

  def leave(*args)
    tx_with_echo("AT+CWQAP")
  end

  def clear(*args)
    return unless socket

    until socket.eof? do
      puts "clearing buffer: #{socket.readline}"
      sleep(SHORT_DELAY)
    end
  end

  protected

  def tx_with_echo(command, check_status=true)
    result = tx(command) do |line|
      puts line.gsub("\r", "\n")
    end
    result_status = check_status ? GOOD_STATUS_CODES.include?(result.last) : true
    puts "STATUS: Houston, we have a problem" unless result_status
    result_status
  end

  # Command: transmit the +command+ and return the result
  def tx(command)
    return [] unless socket

    socket.write "#{command}\r\n"
    sleep(SHORT_DELAY)

    # hum, this is more involved than would be ideal to account for sketchy serial comms
    buffer =[]
    retries = 0
    retry_limit = 4
    unfinished_line = nil

    begin
      lines = socket.readlines
      if lines.empty?
        sleep(SHORT_DELAY)
        retries += 1
      else
        lines.each_with_object(buffer) do |raw_line, memo|
          line = raw_line.chomp.chomp
          if line == raw_line
            unfinished_line ||= ''
            unfinished_line << line
          else
            line, unfinished_line = unfinished_line + line, nil if unfinished_line
            memo << line
            yield line if block_given?
          end
        end
      end
    end until ALL_STATUS_CODES.include?(buffer.last) || retries > retry_limit
    if unfinished_line
      yield unfinished_line if block_given?
      buffer << unfinished_line
    end
    buffer
  end
end

# parse command parameters
port_spec,opcode,params = ARGV.shift, ARGV.shift, ARGV
port_name,baud_rate = port_spec.split(':') if port_spec
baud_rate = baud_rate.to_i
baud_rate = 115200 unless baud_rate > 0

# invoke the requested operation, else show some help
if opcode && port_name
  EspyClient.new(port_name, 'baud' => baud_rate).send(opcode, *params)
else
  puts <<-EOS

Usage:
  #{$0} port_spec cmd

Where port_spec is the serial port name, with optional baud rate qualifier:
  /dev/tty.wchusbserial2420         # 115200 baud rate (default)
  /dev/tty.wchusbserial2420:9600    # 9600 baud rate

Where cmd is one of:

  status             : check ESP8266 status and get device info
  reset              : reset the ESP8266
  ls                 : list access points
  join ssid password : join access point "ssid" with "password"
  get url            : get web page with address "url"
  leave              : disconnect from access point

Example:
  #{$0} /dev/tty.wchusbserial2420 status
  #{$0} /dev/tty.wchusbserial2420:115200 ls
  #{$0} /dev/tty.wchusbserial2420:9600 join MySSID mypassword
  #{$0} /dev/tty.wchusbserial2420 get http://192.168.10.87/time/now.txt

  EOS
end