Mekayl's Session Zones

//version=5
indicator("Mekayl's Session zones", overlay=true, max_boxes_count=200)

// --- Colors
asiaFill = color.new(#3b3333, 80)
preLdnFill = color.new(#292323, 80)
ldnFill = color.new(#242222, 80)
preNyFill = color.new(#443322, 80)
nyFill = color.new(#664422, 80)

asiaBorder = color.new(#4d718f, 0)
preLdnBorder = color.new(#00897B, 0)
ldnBorder = color.new(#B2EBF2, 0)
preNyBorder = color.new(#FFA500, 0)
nyBorder = color.new(#FF8C00, 0)

// --- Sessions
asia_sess = "0100-0600"
preldn_sess = "0600-0800"
ldn_sess = "0800-1200"
preNY_sess = "1200-1300"
ny_sess = "1300-1700"
tz = "Europe/London"

// --- Variables for boxes & labels
var box asia_box = na
var label asia_label = na
var box pre_box = na
var label pre_label = na
var box ldn_box = na
var label ldn_label = na
var box preNY_box = na
var label preNY_label = na
var box ny_box = na
var label ny_label = na

// --- Function to get horizontal center above box
f_label_xy(b) =>
x = (box.get_left(b) + box.get_right(b)) / 2
y = box.get_top(b) + 3 * syminfo.mintick
[x, y]

// --- Asia box
asia_in = not na(time(timeframe.period, asia_sess, tz))
if asia_in
if na(asia_box)
asia_box := box.new(left=bar_index, top=high, right=bar_index, bottom=low, bgcolor=asiaFill, border_color=asiaBorder, border_width=2)
[x, y] = f_label_xy(asia_box)
asia_label := label.new(x, y, "asia", style=label.style_none, textcolor=color.new(asiaBorder,0), size=size.normal)
else
box.set_right(asia_box, bar_index)
box.set_top(asia_box, math.max(box.get_top(asia_box), high))
box.set_bottom(asia_box, math.min(box.get_bottom(asia_box), low))
[x, y] = f_label_xy(asia_box)
label.set_xy(asia_label, x, y)
else
if not na(asia_box)
box.set_right(asia_box, bar_index)
asia_box := na
asia_label := na

// --- Pre-London box
pre_in = not na(time(timeframe.period, preldn_sess, tz))
if pre_in
if na(pre_box)
pre_box := box.new(left=bar_index, top=high, right=bar_index, bottom=low, bgcolor=preLdnFill, border_color=preLdnBorder, border_width=2)
[x, y] = f_label_xy(pre_box)
pre_label := label.new(x, y, "pre_ldn", style=label.style_none, textcolor=color.new(preLdnBorder,0), size=size.normal)
else
box.set_right(pre_box, bar_index)
box.set_top(pre_box, math.max(box.get_top(pre_box), high))
box.set_bottom(pre_box, math.min(box.get_bottom(pre_box), low))
[x, y] = f_label_xy(pre_box)
label.set_xy(pre_label, x, y)
else
if not na(pre_box)
box.set_right(pre_box, bar_index)
pre_box := na
pre_label := na

// --- London box
ldn_in = not na(time(timeframe.period, ldn_sess, tz))
if ldn_in
if na(ldn_box)
ldn_box := box.new(left=bar_index, top=high, right=bar_index, bottom=low, bgcolor=ldnFill, border_color=ldnBorder, border_width=2)
[x, y] = f_label_xy(ldn_box)
ldn_label := label.new(x, y, "ldn", style=label.style_none, textcolor=color.new(ldnBorder,0), size=size.normal)
else
box.set_right(ldn_box, bar_index)
box.set_top(ldn_box, math.max(box.get_top(ldn_box), high))
box.set_bottom(ldn_box, math.min(box.get_bottom(ldn_box), low))
[x, y] = f_label_xy(ldn_box)
label.set_xy(ldn_label, x, y)
else
if not na(ldn_box)
box.set_right(ldn_box, bar_index)
ldn_box := na
ldn_label := na

// --- Pre-New York box
preNY_in = not na(time(timeframe.period, preNY_sess, tz))
if preNY_in
if na(preNY_box)
preNY_box := box.new(left=bar_index, top=high, right=bar_index, bottom=low, bgcolor=preNyFill, border_color=preNyBorder, border_width=2)
[x, y] = f_label_xy(preNY_box)
preNY_label := label.new(x, y, "pre-ny", style=label.style_none, textcolor=color.new(preNyBorder,0), size=size.normal)
else
box.set_right(preNY_box, bar_index)
box.set_top(preNY_box, math.max(box.get_top(preNY_box), high))
box.set_bottom(preNY_box, math.min(box.get_bottom(preNY_box), low))
[x, y] = f_label_xy(preNY_box)
label.set_xy(preNY_label, x, y)
else
if not na(preNY_box)
box.set_right(preNY_box, bar_index)
preNY_box := na
preNY_label := na

// --- New York box
ny_in = not na(time(timeframe.period, ny_sess, tz))
if ny_in
if na(ny_box)
ny_box := box.new(left=bar_index, top=high, right=bar_index, bottom=low, bgcolor=nyFill, border_color=nyBorder, border_width=2)
[x, y] = f_label_xy(ny_box)
ny_label := label.new(x, y, "ny", style=label.style_none, textcolor=color.new(nyBorder,0), size=size.normal)
else
box.set_right(ny_box, bar_index)
box.set_top(ny_box, math.max(box.get_top(ny_box), high))
box.set_bottom(ny_box, math.min(box.get_bottom(ny_box), low))
[x, y] = f_label_xy(ny_box)
label.set_xy(ny_label, x, y)
else
if not na(ny_box)
box.set_right(ny_box, bar_index)
ny_box := na
ny_label := na