@(lengthUnit = m)
import "../../e2e/executor/inputs/2-5-long-m8-chc-screw.stl" as screw

// Set units
@settings(defaultLengthUnit = mm)

myScrew = screw


surface001 = startSketchOn(XY)

// Define parameters
nTeeth = 21
module = 0.5
pitchDiameter = module * nTeeth
pressureAngle = 20
addendum = module
deddendum = 1.25 * module
baseDiameter = pitchDiameter * cos(toRadians(pressureAngle))
tipDiameter = pitchDiameter + 2 * module
gearHeight = 3

// Interpolate points along the involute curve
cmo = 101
rs = map([0..cmo], fn(i) {
  return baseDiameter / 2 + i / cmo * (tipDiameter - baseDiameter) / 2
})

// Calculate operating pressure angle
angles = map(rs, fn(r) {
  return toDegrees(  acos(baseDiameter / 2 / r))
})

// Calculate the involute function
invas = map(angles, fn(a) {
  return tan(toRadians(a)) - toRadians(a)
})

// Map the involute curve
xs = map([0..cmo], fn(i) {
  return rs[i] * cos(invas[i])
})

ys = map([0..cmo], fn(i) {
  return rs[i] * sin(invas[i])
})

// Extrude the gear body
body = startSketchOn(XY)
  |> circle(center = [0, 0], radius = baseDiameter / 2)
  |> extrude(length = gearHeight)

toothAngle = 360 / nTeeth / 1.5

// Plot the involute curve
fn leftInvolute(i, sg) {
  j = 100 - i // iterate backwards
  return line(sg, endAbsolute = [xs[j], ys[j]])
}

fn rightInvolute(i, sg) {
  x = rs[i] * cos(toRadians(-toothAngle + toDegrees(atan(ys[i] / xs[i]))))
  y = -rs[i] * sin(toRadians(-toothAngle + toDegrees(atan(ys[i] / xs[i]))))
  return line(sg, endAbsolute = [x, y])
}

// Draw gear teeth
start = startSketchOn(XY)
  |> startProfileAt([xs[101], ys[101]], %)
teeth = reduce([0..100], start, leftInvolute)
  |> arc(
       angleStart = 0,
       angleEnd = toothAngle,
       radius = baseDiameter / 2,
     )
  |> reduce([1..101], %, rightInvolute)
  |> close()
  |> extrude(length = gearHeight)
  |> patternCircular3d(
       axis = [0, 0, 1],
       center = [0, 0, 0],
       instances = nTeeth,
       arcDegrees = 360,
       rotateDuplicates = true,
     )

// Define the constants of the keyway and the bore hole
keywayWidth = 0.250
keywayDepth = keywayWidth / 2
holeDiam = 2
holeRadius = 1
startAngle = asin(keywayWidth / 2 / holeRadius)

// Sketch the keyway and center hole and extrude
keyWay = startSketchOn(body, face = END)
  |> startProfileAt([
       holeRadius * cos(startAngle),
       holeRadius * sin(startAngle)
     ], %)
  |> xLine(length = keywayDepth)
  |> yLine(length = -keywayWidth)
  |> xLine(length = -keywayDepth)
  |> arc(
       angleStart = -1 * toDegrees(startAngle) + 360,
       angleEnd = 180,
       radius = holeRadius,
     )
  |> arc(
       angleStart = 180,
       angleEnd = toDegrees(startAngle),
       radius = holeRadius,
     )
  |> close()
  |> extrude(length = -gearHeight)

myScrew
  |> translate(y=10)