---------------------------------------------------------------------------
-- @author Uli Schlachter
-- @copyright 2010 Uli Schlachter
-- @release @AWESOME_VERSION@
---------------------------------------------------------------------------

local capi = {
    drawin = drawin,
    root = root,
    awesome = awesome
}
local setmetatable = setmetatable
local pairs = pairs
local type = type
local table = table
local string_format = string.format
local color = require("gears.color")
local object = require("gears.object")
local sort = require("gears.sort")
local beautiful = require("beautiful")
local surface = require("gears.surface")
local cairo = require("lgi").cairo

--- This provides widget box windows. Every wibox can also be used as if it were
-- a drawin. All drawin functions and properties are also available on wiboxes!
-- wibox
local wibox = { mt = {} }
wibox.layout = require("wibox.layout")
wibox.widget = require("wibox.widget")

local function do_redraw(_wibox)
    if not _wibox.drawin.visible then
        return
    end

    local geom = _wibox.drawin:geometry()
    local cr = cairo.Context(surface(_wibox.drawin.surface))

    -- Draw the background
    cr:save()
    -- This is pseudo-transparency: We draw the wallpaper in the background
    local wallpaper = surface(capi.root.wallpaper())
    if wallpaper then
        cr.operator = cairo.Operator.SOURCE
        cr:set_source_surface(wallpaper, -_wibox.drawin.x, -_wibox.drawin.y)
        cr:paint()
    end

    cr.operator = cairo.Operator.OVER
    cr:set_source(_wibox.background_color)
    cr:paint()
    cr:restore()

    -- Draw the widget
    _wibox._widget_geometries = {}
    if _wibox.widget and not _wibox.widget.__fake_widget then
        cr:set_source(_wibox.foreground_color)
        _wibox.widget:draw(_wibox, cr, geom.width, geom.height)
        _wibox:widget_at(_wibox.widget, 0, 0, geom.width, geom.height)
    end

    _wibox.drawin:refresh()
end

--- Register a widget's position.
-- This is internal, don't call it yourself! Only wibox.layout.base.draw_widget
-- is allowed to call this.
function wibox.widget_at(_wibox, widget, x, y, width, height)
    local t = {
        widget = widget,
        x = x, y = y,
        width = width, height = height
    }
    table.insert(_wibox._widget_geometries, t)
end

--- Find a widget by a point.
-- The wibox must have drawn itself at least once for this to work.
-- @param wibox The wibox to look at
-- @param x X coordinate of the point
-- @param y Y coordinate of the point
-- @return A sorted table with all widgets that contain the given point. The
--         widgets are sorted by relevance.
function wibox.find_widgets(_wibox, x, y)
    local matches = {}
    -- Find all widgets that contain the point
    for k, v in pairs(_wibox._widget_geometries) do
        local match = true
        if v.x > x or v.x + v.width <= x then match = false end
        if v.y > y or v.y + v.height <= y then match = false end
        if match then
            table.insert(matches, v)
        end
    end

    -- Sort the matches by area, the assumption here is that widgets don't
    -- overlap and so smaller widgets are "more specific".
    local function cmp(a, b)
        local area_a = a.width * a.height
        local area_b = b.width * b.height
        return area_a < area_b
    end
    sort(matches, cmp)

    return matches
end

--- Set the widget that the wibox displays
function wibox.set_widget(_wibox, widget)
    if _wibox.widget and not _wibox.widget.__fake_widget then
        -- Disconnect from the old widget so that we aren't updated due to it
        _wibox.widget:disconnect_signal("widget::updated", _wibox.draw)
    end

    if not widget then
        _wibox.widget = { __fake_widget = true }
    else
        _wibox.widget = widget
        widget:connect_signal("widget::updated", _wibox.draw)
    end

    -- Make sure the wibox is updated
    _wibox.draw()
end

--- Set the background of the wibox
-- @param wibox The wibox to use
-- @param c The background to use. This must either be a cairo pattern object,
--          nil or a string that gears.color() understands.
function wibox.set_bg(_wibox, c)
    local c = c or "#000000"
    if type(c) == "string" or type(c) == "table" then
        c = color(c)
    end
    _wibox.background_color = c
    _wibox.draw()
end

--- Set the foreground of the wibox
-- @param wibox The wibox to use
-- @param c The foreground to use. This must either be a cairo pattern object,
--          nil or a string that gears.color() understands.
function wibox.set_fg(_wibox, c)
    local c = c or "#FFFFFF"
    if type(c) == "string" or type(c) == "table" then
        c = color(c)
    end
    _wibox.foreground_color = c
    _wibox.draw()
end

--- Helper function to make wibox:buttons() work as expected
function wibox.buttons(box, ...)
    return box.drawin:buttons(...)
end

--- Helper function to make wibox:struts() work as expected
function wibox.struts(box, ...)
    return box.drawin:struts(...)
end

--- Helper function to make wibox:geometry() work as expected
function wibox.geometry(box, ...)
    return box.drawin:geometry(...)
end

local function emit_difference(name, list, skip)
    local function in_table(table, val)
        for k, v in pairs(table) do
            if v == val then
                return true
            end
        end
        return false
    end

    for k, v in pairs(list) do
        if not in_table(skip, v) then
            v:emit_signal(name)
        end
    end
end

local function handle_leave(_wibox)
    emit_difference("mouse::leave", _wibox._widgets_under_mouse, {})
    _wibox._widgets_under_mouse = {}
end

local function handle_motion(_wibox, x, y)
    if x < 0 or y < 0 or x > _wibox.drawin.width or y > _wibox.drawin.height then
        return handle_leave(_wibox)
    end

    -- Build a plain list of all widgets on that point
    local widgets_list = _wibox:find_widgets(x, y)
    local widgets = {}
    for k, v in pairs(widgets_list) do
        widgets[#widgets + 1] = v.widget
    end

    -- First, "leave" all widgets that were left
    emit_difference("mouse::leave", _wibox._widgets_under_mouse, widgets)
    -- Then enter some widgets
    emit_difference("mouse::enter", widgets, _wibox._widgets_under_mouse)

    _wibox._widgets_under_mouse = widgets
end

local function setup_signals(_wibox)
    local w = _wibox.drawin

    local function clone_signal(name)
        _wibox:add_signal(name)
        -- When "name" is emitted on wibox.drawin, also emit it on wibox
        w:connect_signal(name, function(_, ...)
            _wibox:emit_signal(name, ...)
        end)
    end
    clone_signal("mouse::enter")
    clone_signal("mouse::leave")
    clone_signal("mouse::move")
    clone_signal("property::border_color")
    clone_signal("property::border_width")
    clone_signal("property::buttons")
    clone_signal("property::cursor")
    clone_signal("property::height")
    clone_signal("property::ontop")
    clone_signal("property::opacity")
    clone_signal("property::struts")
    clone_signal("property::visible")
    clone_signal("property::widgets")
    clone_signal("property::width")
    clone_signal("property::x")
    clone_signal("property::y")

    -- Update the wibox when its geometry changes
    w:connect_signal("property::height", _wibox.draw)
    w:connect_signal("property::width", _wibox.draw)
    w:connect_signal("property::visible", function()
        if w.visible then
            capi.awesome.connect_signal("wallpaper_changed", _wibox.draw)
            _wibox.draw()
        else
            capi.awesome.disconnect_signal("wallpaper_changed", _wibox.draw)
        end
    end)

    local function button_signal(name)
        w:connect_signal(name, function(w, x, y, ...)
            local widgets = _wibox:find_widgets(x, y)
            for k, v in pairs(widgets) do
                -- Calculate x/y inside of the widget
                local lx = x - v.x
                local ly = y - v.y
                v.widget:emit_signal(name, lx, ly, ...)
            end
        end)
    end
    button_signal("button::press")
    button_signal("button::release")

    _wibox:connect_signal("mouse::move", handle_motion)
    _wibox:connect_signal("mouse::leave", handle_leave)
end

local function new(args)
    local ret = object()
    local w = capi.drawin(args)

    ret.drawin = w

    for k, v in pairs(wibox) do
        if type(v) == "function" then
            ret[k] = v
        end
    end

    -- This is to make sure that the wibox will only be redrawn once even when
    -- we receive multiple widget::updated signals.
    ret._redraw_pending = false
    ret._do_redraw = function()
        ret._redraw_pending = false
        capi.awesome.disconnect_signal("refresh", ret._do_redraw)
        do_redraw(ret)
    end

    -- Connect our signal when we need a redraw
    ret.draw = function()
        if not ret._redraw_pending then
            capi.awesome.connect_signal("refresh", ret._do_redraw)
            ret._redraw_pending = true
        end
    end

    setup_signals(ret)

    -- Set the default background
    ret:set_bg(args.bg or beautiful.bg_normal)
    ret:set_fg(args.fg or beautiful.fg_normal)

    -- Make sure the wibox is drawn at least once
    ret.draw()

    -- Due to the metatable below, we need this trick
    ret.widget = { __fake_widget = true }
    ret._widget_geometries = {}
    ret._widgets_under_mouse = {}

    -- Redirect all non-existing indexes to the "real" drawin
    setmetatable(ret, {
        __index = w,
        __newindex = w
    })

    return ret
end

--- Redraw a wibox. You should never have to call this explicitely because it is
-- automatically called when needed.
-- @param wibox
-- @name draw
-- @class function

--- Widget box object.
-- Every wibox "inherits" from a drawin and you can use all of drawin's
-- functions directly on this as well. When creating a wibox, you can specify a
-- "fg" and a "bg" color as keys in the table that is passed to the constructor.
-- All other arguments will be passed to drawin's constructor.
-- @class table
-- @name drawin

function wibox.mt:__call(...)
    return new(...)
end

return setmetatable(wibox, wibox.mt)

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