--------------------------------------------
-- Author: Gregor Best                    --
-- Copyright 2009, 2010, 2011 Gregor Best --
--------------------------------------------

local tostring = tostring
local setmetatable = setmetatable
local io = {
  popen = io.popen
}
local capi = {
  mouse = mouse
}
local math = {
  floor = math.floor
}

local naughty = require("naughty")
local awful = require("awful")
local wibox = require("wibox")
local gears = require("gears")

local widget = wibox.widget.textbox()
local status_text = {
  ["charged"] = "↯",
  ["full"] = "↯",
  ["high"] = "↯",
  ["discharging"] = "▼",
  ["not connected"] = "▼",
  ["charging"] = "▲",
  ["unknown"] = "⌁"
}

local battery = { mt = {}, status_callback = nil }

-- {{{ upower backend
local tonumber = tonumber

local function defaults_to_key(t)
  local function return_key__index(_, key)
    return key
  end

  return setmetatable(t, { __index = return_key__index })
end

local function popen(cmd)
  return io.popen('LC_ALL=C LANG=C ' .. cmd .. ' 2>/dev/null')
end

local function match_case(input, ...)
  local args = { ... }

  for i = 1, #args, 2 do
    local pattern = args[i]
    local action  = args[i + 1]

    local matches = { string.match(input, pattern) }

    if matches[1] then
      action(table.unpack(matches))
      break
    end
  end
end



local upower_backend = { name = 'upower' }

local upower_status_mapping = defaults_to_key {
  ['fully-charged'] = 'charged',
}

function upower_backend:clone(clone)
  return setmetatable(clone or {}, { __index = self })
end

function upower_backend:configure()
  local fd, err = popen('upower -e')
  if not fd then
    return nil, err
  end

  local battery_filenames = {}
  for line in fd:lines() do
    if line:match('battery_BAT') then
      battery_filenames[#battery_filenames + 1] = line
    end
  end
  fd:close()

  if #battery_filenames > 0 then
    return upower_backend:clone { filenames = battery_filenames }
  end
end

function upower_backend:state()
  local results = {}

  for i = 1, #self.filenames do
    local filename = self.filenames[i]

    local rv = {}
    local fd, err = popen('upower -i ' .. filename)

    if not fd then
      return nil, err
    end

    local function handle_time(time, units)
      if time == 'unknown' then
        time = nil
      elseif units == 'hour' or units == 'hours' then
        time = math.floor(time * 60)
      elseif units == 'minute' or units == 'minutes' then
        time = tonumber(math.floor(time))
      else
        time = 0
      end

      rv.time = time
    end

    for line in fd:lines() do
      match_case(line,
        '^%s*percentage:%s*(%d+)', function(charge)
          rv.charge = tonumber(charge)
        end,
        '%s*time to empty:%s*(%S+)%s*(%w*)', handle_time,
        '%s*time to full:%s*(%S+)%s*(%w*)', handle_time,
        'state:%s*(%S+)', function(status)
          rv.status = upower_status_mapping[status]
        end)
    end
    fd:close()
    results[i] = rv
  end

  return table.unpack(results)
end

function upower_backend:details()
  local results = ''

  for i = 1, #self.filenames do
    local filename = self.filenames[i]

    local pipe, err = popen('upower -i ' .. filename)

    if not pipe then
      return nil, err
    end

    local output = pipe:read '*a'
    results = results .. '\n' .. output:gsub('^\n', '')
  end

  return results
end
-- }}}





local backend = upower_backend:configure()

local inverted = false
local show_time = false
local cycle_count = 0
local previous_state

local function update(force)
  if force then
    cycle_count = 0
  end
  if cycle_count == 0 then
    previous_state = { backend:state() }
  end
  cycle_count = (cycle_count + 1) % 60
  local bats = previous_state

  if #bats == 0 then
    widget:set_markup("no data")
    return
  end

  local markup = ''

  for i = 1, #bats do
    local bat = bats[i]
    local color

    local blinking = false

    local charge = bat.charge

    if charge == nil then
      color = '#900000'
      charge = 'Unknown charge'
    elseif charge >= 60 then
      color = '#009000'
    elseif charge > 35 then
      color = '#909000'
    else
      color = '#900000'
      blinking = bat.charge <= 20 and (bat.status == 'discharging' or bat.status == 'not connected')
    end

    local status = status_text[bat.status] or 'unknown'

    local battery_status

    if battery.status_callback then
      battery.status_callback(bat)
    end

    if blinking and inverted then
      battery_status = status .. ' ' .. awful.util.escape(tostring(bat.charge)) .. '%'
    else
      battery_status = '<span foreground="' .. tostring(color) .. '">' .. tostring(status) .. '</span>'.. ' ' .. awful.util.escape(tostring(bat.charge)) .. '%'
    end

    if bat.time and show_time then
      local hours   = math.floor(bat.time / 60)
      local minutes = bat.time % 60

      battery_status = battery_status .. ' ' .. awful.util.escape(string.format('%02d:%02d', hours, minutes))
    end

    if blinking and inverted then
      battery_status = '<span background="' .. tostring(color) .. '">' .. tostring(battery_status) .. '</span>'
    end
    inverted = not inverted

    if i == 1 then
      markup = markup .. battery_status
    else
      markup = markup .. ' ' .. battery_status
    end
  end

  widget:set_markup(markup)
end

local function detail ()
  local details = backend:details()

  if not details then
    details = 'no details available'
  end
  naughty.notify({
    text = details,
    screen = capi.mouse.screen,
  })
  update(true)
end

function get_data()
  local bats = { backend:state() }
  if bats then
    return bats[1]
  end
end

widget:buttons(awful.util.table.join(
  awful.button({ }, 1, detail)
))

return setmetatable(battery, { __call = function ()
  update()
  gears.timer({
      timeout=30,
      autostart=true,
      callback=update,
  })
  return widget
end })

-- vim:ft=lua:ts=2:sw=2:sts=2:tw=80:et