Asia Session Box

// This Pine Script™ code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/

//@version=6
indicator("Asia Session Box", shorttitle="AsiaBox", overlay=true, max_boxes_count=500)

// ============================================================
// INPUTS
// ============================================================
i_startHour    = input.int(7,              "Session Start Hour (PHT)",  minval=0, maxval=23)
i_borderColor  = input.color(color.orange, "Border Color")
i_borderWidth  = input.int(1,              "Border Width",              minval=1, maxval=4)

// ============================================================
// TIME HELPERS  (all times in PHT = Asia/Manila, UTC+8, no DST)
// ============================================================
h = hour(time, "Asia/Manila")
m = minute(time, "Asia/Manila")

// 07:00–07:30 window (configurable start hour, always 30 min long)
inSessionBox = (h == i_startHour) and (m < 30)

// Detect window-start bar (first bar inside the window each day)
windowStart = inSessionBox and not inSessionBox[1]

// Detect window-end bar (first bar outside the window after being inside)
windowEnd = not inSessionBox and inSessionBox[1]

// ============================================================
// STATE — reset each new window
// ============================================================
var box   sessionBox  = na
var float sessionHigh = na
var float sessionLow  = na

// ============================================================
// BOX LOGIC
// ============================================================

// --- Window opens: create a fresh box ---
if windowStart
    sessionHigh := high
    sessionLow  := low
    sessionBox  := box.new(
         left         = bar_index,
         right        = bar_index,
         top          = high,
         bottom       = low,
         bgcolor      = na,           // border only, no fill
         border_color = i_borderColor,
         border_width = i_borderWidth)

// --- While inside the window: expand the box to the running range ---
if inSessionBox and not na(sessionBox)
    sessionHigh := math.max(sessionHigh, high)
    sessionLow  := math.min(sessionLow,  low)
    box.set_top(sessionBox,    sessionHigh)
    box.set_bottom(sessionBox, sessionLow)
    box.set_right(sessionBox,  bar_index)

// --- Window closes: freeze the right edge (do NOT extend further) ---
if windowEnd and not na(sessionBox)
    box.set_right(sessionBox, bar_index)