# -*- coding: utf-8 -*-
from math import pi

linpar("A:OutsideDia", 914.4, 36)
linpar("B:Height", 406.4, 16)
intpar("N:Sides", 6)
linpar("C:FlangeWidth", 38.1, 1.5)
linpar("D:HoleDia", 6.35, 0.25)

def dashed_vline(x, y0, y1, dash, gap):
    y = y0
    while y < y1:
        yb = y + dash
        if yb > y1:
            yb = y1
        moveto(x, y)
        lineto(x, yb)
        y = yb + gap

def dashed_hline(x0, x1, y, dash, gap):
    x = x0
    while x < x1:
        xb = x + dash
        if xb > x1:
            xb = x1
        moveto(x, y)
        lineto(xb, y)
        x = xb + gap

def draw_half_piece(yb, piece_len, panel_len, sides, flange_w, hole_dia, edge, gap, relief_w):
    yt = yb + B

    # Relief slot geometry
    relief_seg = (B - 2.0 * edge - gap) / 2.0
    if relief_seg < 1:
        relief_seg = 1

    bot_y0 = yb + edge
    bot_y1 = yb + edge + relief_seg
    top_y0 = yt - edge - relief_seg
    top_y1 = yt - edge

    # Main outline
    rect(0, yb, piece_len, yt)

    # Bend locations: left flange bend + bends between the main panels
    bend_x = [flange_w]
    for k in range(1, sides):
        bend_x.append(flange_w + k * panel_len)

    # Split relief slots
    for x in bend_x:
        rect(x - relief_w / 2.0, bot_y0, x + relief_w / 2.0, bot_y1)
        rect(x - relief_w / 2.0, top_y0, x + relief_w / 2.0, top_y1)

    # Longer panel center lines
    cl_y0 = bot_y1 + gap * 0.05
    cl_y1 = top_y0 - gap * 0.05
    dash_v = max(B * 0.06, 10.0)
    gap_v = dash_v * 0.55
    if cl_y1 > cl_y0:
        for i in range(sides):
            x0 = flange_w + i * panel_len
            x1 = flange_w + (i + 1) * panel_len
            xc = (x0 + x1) / 2.0
            dashed_vline(xc, cl_y0, cl_y1, dash_v, gap_v)

    # Full-length horizontal center line for each half piece
    dash_h = max(piece_len * 0.020, 18.0)
    gap_h = dash_h * 0.55
    dashed_hline(0, piece_len, yb + B / 2.0, dash_h, gap_h)

    # Matching 3-hole bolt pattern left and right
    hole_x = max(flange_w * 0.35, hole_dia)
    x_left = hole_x
    x_right = piece_len - hole_x

    hole_margin = B * 0.09
    y_bottom = yb + hole_margin
    y_mid = yb + B / 2.0
    y_top = yt - hole_margin

    circle(x_left, y_bottom, hole_dia / 2.0)
    circle(x_left, y_mid, hole_dia / 2.0)
    circle(x_left, y_top, hole_dia / 2.0)

    circle(x_right, y_bottom, hole_dia / 2.0)
    circle(x_right, y_mid, hole_dia / 2.0)
    circle(x_right, y_top, hole_dia / 2.0)

def generate():
    sides = N
    if sides < 3:
        sides = 3

    # Full fire ring circumference from OD
    full_flat = pi * A

    # Output two equal half pieces automatically
    half_flat = full_flat / 2.0
    panel_len = half_flat / sides
    piece_len = C + half_flat

    # Fixed reliefs. Use simple unit inference so 0.75 in remains 19.05 mm in metric mode.
    if A > 100 or B > 50:
        edge = 19.05
        gap = 19.05
        relief_w = 3.175
    else:
        edge = 0.75
        gap = 0.75
        relief_w = 0.125

    # Keep relief geometry valid for short heights
    if B <= edge * 2.0 + gap + 5:
        edge = B * 0.18
        gap = B * 0.18

    piece_gap = max(B * 0.18, 35.0)

    # Two identical half pieces
    draw_half_piece(0, piece_len, panel_len, sides, C, D, edge, gap, relief_w)
    draw_half_piece(B + piece_gap, piece_len, panel_len, sides, C, D, edge, gap, relief_w)

    # Minimal readable preview labels
    oy = max(B * 0.12, 28.0)
    dimtxt("Input OD = full ring. Output = 2 half pieces.", piece_len * 0.50, 2.0 * B + piece_gap + oy)
    dimtxt("Flat per piece = A OD x 3.1416 / 2", piece_len * 0.50, 2.0 * B + piece_gap + oy * 1.35)

    dimtxt("A OD", piece_len * 0.10, 2.0 * B + piece_gap + oy * 1.75)
    dimtxt("B Height", -max(piece_len * 0.06, 35.0), B * 0.50)
    dimtxt("N Sides per half", piece_len * 0.82, 2.0 * B + piece_gap + oy * 1.75)
    dimtxt("C Flange", C * 0.50, -oy)
    dimtxt("D Hole dia", piece_len * 0.88, 2.0 * B + piece_gap + oy * 0.55)