Colour Change Rings for Conky Lua by mrmrwat

--[[
    Colour Change Rings by mrmrwat (24.03.2013)
    based on Ring Meters v.1.2.1 by londonali1010 (20.10.2009)
    and inspired by PolarClock by pixelbreaker

    New features include support for color-change rings
    and millisecond precision for smooth ring movement

    NB. Requires lua socket for socket.gettime() function
--]]

settings_table = {
    {
        name = 'time',
        arg = '%I',
        max = 12,
        bg_colour = 0xffffff,
        bg_alpha = 0.1,
        fg_colour = 'rainbow_bgr',
        fg_alpha = 0.6,
        x = 146, y = 165,
        radius = 75,
        thickness = 12,
        start_angle = 0,
        end_angle = 360
    },
    -- Uncomment below and comment above for 24 hour clock instead of 12 hour clock
    --[[{
        name = 'time',
        arg = '%H',
        max = 24,
        bg_colour = 0xffffff,
        bg_alpha = 0.1,
        fg_colour = 'rainbow_bgr',
        fg_alpha = 0.6,
        x = 146, y = 165,
        radius = 75,
        thickness = 12,
        start_angle = 0,
        end_angle = 360
    },]]
    {
        name = 'time',
        arg = '%M',
        max = 60,
        bg_colour = 0xffffff,
        bg_alpha = 0.1,
        fg_colour = 'rainbow_bgr',
        fg_alpha = 0.6,
        x = 146, y = 165,
        radius = 90,
        thickness = 7,
        start_angle = 0,
        end_angle = 360
    },
    {
        name = 'time',
        arg = '%S',
        max = 60,
        bg_colour = 0xffffff,
        bg_alpha = 0.1,
        fg_colour = 'rainbow_bgr',
        fg_alpha = 0.6,
        x = 146, y = 165,
        radius = 120,
        thickness = 4,
        start_angle = 0,
        end_angle = 360
    },
}

require 'cairo'
require 'socket'

function rgb_to_r_g_b(colour, alpha)
    return ((colour / 0x10000) % 0x100) / 255.,
        ((colour / 0x100) % 0x100) / 255.,
        (colour % 0x100) / 255., alpha
end

function draw_ring(cr, t, pt)
    local w, h = conky_window.width, conky_window.height

    local xc, yc, ring_r, ring_w, sa, ea = pt['x'], pt['y'],
        pt['radius'], pt['thickness'],
        pt['start_angle'], pt['end_angle']
    local bgc, bga, fgc, fga = pt['bg_colour'], pt['bg_alpha'],
        pt['fg_colour'], pt['fg_alpha']

    local angle_0 = sa * (2 * math.pi / 360) - math.pi / 2
    local angle_f = ea * (2 * math.pi / 360) - math.pi / 2
    local t_arc = t * (angle_f - angle_0)

    -- Draw background ring

    cairo_arc(cr, xc, yc, ring_r, angle_0, angle_f)
    cairo_set_source_rgba(cr, rgb_to_r_g_b(bgc, bga))
    cairo_set_line_width(cr, ring_w)
    cairo_stroke(cr)

    -- Draw indicator ring

    cairo_arc(cr, xc, yc, ring_r, angle_0, angle_0+t_arc)

    -- New if statement holds colour change logic

    local r = 0
    local g = 0
    local b = 0
    if fgc == 'rainbow_rgb' then
        if t < 1 / 6 then
            r, g, b = 1, t * 6, 0
        elseif t < 2 / 6 then
            r, g, b = 1 - ((t * 6) - 1), 1, 0
        elseif t < 3 / 6 then
            r, g, b = 0, 1, (t * 6) - 2
        elseif t < 4 / 6 then
            r, g, b = 0, 1 - ((t * 6) - 3), 1
        elseif t < 5 / 6 then
            r, g, b = (t * 6) - 4, 0, 1
        elseif t < 6 / 6 then
            r, g, b = 1, 0, 1 - ((t * 6) - 5)
        end
        cairo_set_source_rgba(cr, r, g, b, fga)
    elseif fgc == 'rainbow_bgr' then
        if t < 1 / 6 then
            r, g, b = 0, t * 6, 1
        elseif t < 2 / 6 then
            r, g, b = 0, 1, 1 - ((t * 6) - 1)
        elseif t < 3 / 6 then
            r, g, b = (t * 6) - 2, 1, 0
        elseif t < 4 / 6 then
            r, g, b = 1, 1 - ((t * 6) - 3), 0
        elseif t < 5 / 6 then
            r, g, b = 1, 0, (t * 6) - 4
        elseif t < 6 / 6 then
            r, g, b = 1 - ((t * 6) - 5), 0, 1
        end
        cairo_set_source_rgba(cr, r, g, b, fga)
    elseif fgc == 'traffic' then
        if t < 1 / 3 then
            r, g, b = 0, 1, 0
        elseif t < 2 / 3 then
            r, g, b = (t * 3) - 1, 1, 0
        elseif t < 3 / 3 then
            r, g, b = 1, 1 - ((t * 3) - 2), 0
        end
        cairo_set_source_rgba(cr, r, g, b, fga)
    elseif fgc == 'traffic_rev' then
        if t < 1 / 3 then
            r, g, b = 1, 0, 0
        elseif t < 2 / 3 then
            r, g, b = 1, (t * 3) - 1, 0
        elseif t < 3 / 3 then
            r, g, b = 1 - ((t * 3) - 2), 1, 0
        end
        cairo_set_source_rgba(cr, r, g, b, fga)
    else
        -- Original set_source code

        cairo_set_source_rgba(cr, rgb_to_r_g_b(fgc, fga))
    end

    cairo_stroke(cr)
end

function conky_ring_stats()
    local function setup_rings(cr, pt)
        local str = ''
        local value = 0

        -- New if statement holds millisecond precision clock logic

        if pt['name'] == 'time' then
            local epoch_time = os.time()
            local mils = socket.gettime() - epoch_time
            local secs = conky_parse('${time %S}')
            secs = tonumber(secs) + mils
            local mins = conky_parse('${time %M}')
            mins = tonumber(mins)
            local hrs  = conky_parse('${time %I}')
            hrs  = tonumber(hrs)

            if pt['arg'] == '%I' then
                value = (hrs % 12) + (mins / 60) + (secs / 3600)
            elseif pt['arg'] == '%H' then
                value = hrs + (mins / 60) + (secs / 3600)
            elseif pt['arg'] == '%M' then
                value = mins + (secs / 60)
            elseif pt['arg'] == '%S' then
                value = secs
            else
                -- Original conky_parse code replicated here to prevent
                -- breakages in times which don't use %I, %H, %M, or %S

                str = string.format('${%s %s}', pt['name'], pt['arg'])
                str = conky_parse(str)
                value = tonumber(str)
            end
        else
            -- Original conky_parse code

            str = string.format('${%s %s}', pt['name'], pt['arg'])
            str = conky_parse(str)
            value = tonumber(str)
        end

        pct = value / pt['max']

        draw_ring(cr, pct, pt)
    end

    if conky_window == nil then return end

    local cs = cairo_xlib_surface_create(conky_window.display,
        conky_window.drawable, conky_window.visual,
        conky_window.width, conky_window.height)
    local cr = cairo_create(cs)

    local updates = conky_parse('${updates}')
    update_num = tonumber(updates)

    if update_num > 5 then
        for i in pairs(settings_table) do
            setup_rings(cr, settings_table[i])
        end
    end
end