---------------------------------------------------------------------------
-- An implementation of my battery_widget widget with a dynamicly generated
-- icon based on the battery percentage level.
--
-- Find more about my battery_widget widget at
-- https://github.com/Aire-One/awesome-battery_widget
--
-- @author Aire-One
-- @copyright 2020 Aire-One
---------------------------------------------------------------------------
local lgi = require 'lgi'
local cairo = lgi.cairo
local rsvg = lgi.Rsvg

local atooltip = require 'awful.tooltip'
local beautiful = require 'beautiful'
local gcolor = require 'gears.color'
local imagebox = require 'wibox.widget.imagebox'

local battery_widget = require 'battery-widget'

local my_battery = {}
local mt = {}

--- Generate a drawing for the battery icon.
-- @tparam number percentage The percentage of battery remaining.
-- @tparam gears.color|string color The color of the drawing.
-- @treturn cairo.ImageSurface The generated surface for the drawing.
function my_battery.draw_battery (percentage, color)
    local svg_handle = rsvg.Handle.new_from_file(beautiful.icon_battery_outline)
    if not svg_handle then return end
    local surface = cairo.ImageSurface.create(cairo.Format.ARGB32, 24, 24)
    local cr = cairo.Context(surface)
    svg_handle:render_cairo(cr)

    local max_height = 14
    local x = 8
    local width = 8
    local height = percentage / 100 * max_height
    local y = 6 + max_height - height

    cr:set_source(gcolor(color))
    cr:rectangle(x, y, width, height)
    cr:fill()

    return surface
end

--- Update handler for the battery widget. This is the function called
-- by the signal system on battery update.
-- @tparam my_battery widget The battery widget to update.
-- @tparam UPowerGLib.Device device The UPower device to monitor.
function my_battery.update (widget, device)
    widget.image = my_battery.draw_battery(device.percentage, widget.color)
end

--- Give the widget template for the battery widget.
-- (It's a basic `wibox.widget.imagebox` for my battery implementation)
function my_battery.widget_template ()
    local widget = imagebox()
    widget.resize = true

    return widget
end

--- Constructor of my battery widget!
-- @tparam table args Table of parameters.
-- @tparam screen|number args.screen The screen of the wodget.
-- @tparam string args.device_path The path of the UPower device to monitor.
-- @tparam gears.color|string args.color Color to use to draw the battery.
-- @treturn my_battery The instantiated widget.
function my_battery.new (args)
    local widget = battery_widget {
        screen = args.screen,
        device_path = args.device_path,
        widget_template = my_battery.widget_template(),
        instant_update = true
    }

    widget.color = args.color

    widget:connect_signal('upower::update', function (w, device)
        my_battery.update(w, device)
    end)

    widget.tooltip = atooltip {
        objects = { widget },
        timer_function = function ()
            return string.format('%3d', widget.device.percentage) .. '%'
        end
    }

    return widget
end

function mt.__call (self, ...)
    return my_battery.new(...)
end

return setmetatable(my_battery, mt)