#!/usr/bin/lua

require "uci"
require("socket")
json=require("json")

function url_decode(str)
  if not str then return nil end
  str = string.gsub (str, "+", " ")
  str = string.gsub (str, "%%(%x%x)", function(h) return
    string.char(tonumber(h,16)) end)
  str = string.gsub (str, "\r\n", "\n")
  return str
end

function split(s, delimiter)
    local result = {};
    for match in (s..delimiter):gmatch("(.-)"..delimiter) do
        result[#result+1] = match;
    end
    return result;
end

function string.starts(String,Start)
   return string.sub(String,1,string.len(Start))==Start
end

function process_playlist(playlist)
  local res={}
  for _,record in pairs(playlist) do
    local splitted = split(record,": ")
    local name = splitted[2]
    local splitted = split(splitted[1],":")
    local id = splitted[1]
    local rectype = splitted[2]
    local rec = {}
    if not (id == "OK") then
      rec["id"] = id
      rec["type"] = rectype
      rec["name"] = name
      res[id] = rec
    end
  end
  return res
end

function process_playlists(playlists)
  local res={}
  for _,record in pairs(playlists) do
    local splitted = split(record,": ")
    if splitted[1]=="playlist" then
      res[#res+1] = splitted[2]
    end
  end
  return res
end

function process_directory(directory)
  local res={}
  for _,record in pairs(directory) do
    local splitted = split(record,": ")
    if splitted[1]=="directory" or splitted[1]=="file" then
      local rec={}
      rec["type"] = splitted[1]
      rec["name"] = splitted[2]
      res[#res+1] = rec
    end
  end
  return res
end

function mpd_new(settings)
    local client = {}
    if settings == nil then settings = {} end

    client.hostname = settings.hostname or "localhost"
    client.port     = settings.port or 6600
    client.desc     = settings.desc or client.hostname
    client.password = settings.password
    client.timeout  = settings.timeout or 1
    client.retry    = settings.retry or 60

    return client
end

function mpd_send(mpd,action,raw)

    local command = string.format("%s\n", action)
    local values = {}

    -- connect to MPD server if not already done.
    if not mpd.connected then
        local now = os.time();
        if not mpd.last_try or (now - mpd.last_try) > mpd.retry then
            mpd.socket = socket.tcp()
            mpd.socket:settimeout(mpd.timeout, 't')
            mpd.last_try = os.time()
            mpd.connected = mpd.socket:connect(mpd.hostname, mpd.port)
            if not mpd.connected then
                return { errormsg = "could not connect" }
            end
            mpd.last_error = nil

            -- Read the server's hello message
            local line = mpd.socket:receive("*l")
            if not line:match("^OK MPD") then -- Invalid hello message?
                mpd.connected = false
                return { errormsg = string.format("invalid hello message: %s", line) }
            else
                _, _, mpd.version = string.find(line, "^OK MPD ([0-9.]+)")
            end

            -- send the password if needed
            if mpd.password then
                local rsp = mpd_send(mpd,string.format("password %s", mpd.password))
                if rsp.errormsg then
                    return rsp
                end
            end
        else
            local retry_sec = mpd.retry - (now - mpd.last_try)
            return { errormsg = string.format("%s (retrying in %d sec)", mpd.last_error, retry_sec) }
        end
    end

    mpd.socket:send(command)

    local line = ""; err=0
    while not line:match("^OK$") do
        line, err = mpd.socket:receive("*l")
        if not line then -- closed,timeout (mpd killed?)
            mpd.last_error = err
            mpd.connected = false
            mpd.socket:close()
            return mpd_send(mpd,action)
        end

        if line:match("^ACK") then
            return { errormsg = line }
        end

        if not raw then

  	  local pattern = string.format("(%s)", ": ")
	  local i = string.find (line, pattern, 0)

          if i ~= nil then
              local key=string.sub(line,1,i-1)
              local value=string.sub(line,i+2,-1)
              values[string.lower(key)] = value
          end

	else

	  values[#values+1]=line

	end
    end

    return values
end

x = uci.cursor()

settings = {}
settings['host'] = x.get("mpd","server","host") or "localhost"
settings['port'] = x.get("mpd","server","port") or 6600
settings['timeout'] = x.get("mpd","server","timeout") or 1

volstep = x.get("mpd","control","volume_step") or 3

password = x.get("mpd","server","password")
if password then
  settings["password"] = password
end

m = mpd_new(settings)

command = url_decode(os.getenv('QUERY_STRING'))

if not command or command=="" then
  command="idle"
end

if command=="play" or command=="pause" or command=="stop" then

  res=mpd_send(m,command)

elseif command=="previous" or command=="next" then

  res=mpd_send(m,"play")
  res=mpd_send(m,command)

elseif command=="idle" then

  m.timeout=30
  res=mpd_send(m,command)

elseif command=="vold" then

  status=mpd_send(m,"status")
  volume=tonumber(status["volume"])
  res=mpd_send(m,"setvol "..(volume-volstep))

elseif command=="volu" then

  status=mpd_send(m,"status")
  volume=tonumber(status["volume"])
  res=mpd_send(m,"setvol "..(volume+volstep))

elseif string.starts(command,"fastfwd") then

  cmd=split(command,"|")
  skip=tonumber(cmd[2])
  if not skip then
    skip=15
  end

  status=mpd_send(m,"status")
  rec_time=status["time"]
  song=status["song"]
  
  if song then

    if rec_time then
      rec_time=split(rec_time,":")
      cur_time=tonumber(rec_time[1])

      track_time=tonumber(rec_time[2])
      cur_time=cur_time+skip
      if cur_time>track_time then
        cur_time=track_time
      end

      mpd_send(m,"seek "..song.." "..cur_time)

    else

      mpd_send(m,"play")

    end  
  
  end

  res={}

elseif string.starts(command,"rewind") then

  cmd=split(command,"|")
  skip=tonumber(cmd[2])
  if not skip then
    skip=15
  end

  status=mpd_send(m,"status")
  rec_time=status["time"]
  song=status["song"]
  
  if song then

    if rec_time then
      rec_time=split(rec_time,":")
      cur_time=tonumber(rec_time[1])

      track_time=tonumber(rec_time[2])
      cur_time=cur_time-skip
      if cur_time<0 then
        cur_time=0
      end

      mpd_send(m,"seek "..song.." "..cur_time)

    else

      mpd_send(m,"play")
      mpd_send(m,"previous")

    end  
  
  end

  res={}

elseif command=="status" then

  res=mpd_send(m,"status")
  song=res["song"]
  playlist=mpd_send(m,"playlist",1)
  pl=process_playlist(playlist)

  if song then 
    res['current_playing']=pl[song]['name']
  else
    res['song']="--"
    res['current_playing']="---"
  end

elseif command=="playlist" then

  playlist=mpd_send(m,"playlist",1)
  res=process_playlist(playlist)

elseif command=="repeat" then

  status=mpd_send(m,"status")
  rep=1-status["repeat"]
  res=mpd_send(m,"repeat "..rep)

elseif string.starts(command,"cpl") then

  cmd=split(command,"|")
  id=cmd[3]
  command=cmd[2]

  if command=="playitem" then
    command="play "..id
    res=mpd_send(m,command)
  end

  if command=="clear" then
    res=mpd_send(m,"clear")
  end

  if command=="remove" then
    command="delete "..id
    res=mpd_send(m,command)
  end

  if command=="moveup" then
    command="swap "..id.." "..(id-1)
    res=mpd_send(m,command)
  end

  if command=="movedown" then
    command="swap "..id.." "..(id+1)
    res=mpd_send(m,command)
  end

elseif string.starts(command,"lists") then

  cmd=split(command,"|")
  command=cmd[2]

  if command=="load" then
    if not cmd[3] then
      lists=mpd_send(m,"listplaylists",1)
      res=process_playlists(lists)
    else
      res=mpd_send(m,"load "..cmd[3],1)
    end
  end

  if command=="save" and cmd[3] then
    res=mpd_send(m,"save "..cmd[3],1)
  end

  if command=="delete" and cmd[3] then
    res=mpd_send(m,"rm "..cmd[3],1)
  end

  if command=="edit" then
    if cmd[3] then
      dir=mpd_send(m,"lsinfo \""..cmd[3].."\"",1)
    else
      dir=mpd_send(m,"lsinfo",1)
    end
    res=process_directory(dir)
  end

  if command=="add" then
    res={}
    if cmd[3] then
      res=mpd_send(m,"add \""..cmd[3].."\"")
    end
  end

end

if not res then
  print("Content-Type: text/plain\r\n")
  print("MPD server - unknown command "..command)
elseif (res['error_msg']) then
  print("Content-Type: text/plain\r\n")
  print("MPD server connection error: "..res['error_msg'])
else
  print "Content-Type: text/plain\r\n"
  print(json.encode(res))
end