## Direct assertion that WaveSurfer decomposes an enemy's (heading, speed) into
## a world velocity with the Tank Royale angle convention: 0 degrees = EAST,
## angles increase counter-clockwise, so vx = cos(h)*s and vy = sin(h)*s.
##
## The classic-Robocode convention (0 = north, clockwise) would swap sin/cos;
## this test fails if anyone reintroduces that bug.

import std/[math, unittest]
import ../test_framework/adversaries/WaveSurfer/src/WaveSurfer

const eps = 1e-9

proc close(a, b: float): bool = abs(a - b) < eps

suite "WaveSurfer enemy velocity decomposition (TR: 0=east, CCW+)":
  test "east heading is +x":
    let v = enemyVelocity(0.0, 10.0)
    check close(v.vx, 10.0)
    check close(v.vy, 0.0)

  test "north heading (90 deg) is +y":
    let v = enemyVelocity(90.0, 10.0)
    check close(v.vx, 0.0)
    check close(v.vy, 10.0)

  test "west heading (180 deg) is -x":
    let v = enemyVelocity(180.0, 10.0)
    check close(v.vx, -10.0)
    check close(v.vy, 0.0)

  test "south heading (270 deg) is -y":
    let v = enemyVelocity(270.0, 10.0)
    check close(v.vx, 0.0)
    check close(v.vy, -10.0)

  test "diagonal 45 deg splits evenly":
    let v = enemyVelocity(45.0, 10.0)
    check close(v.vx, 10.0 / sqrt(2.0))
    check close(v.vy, 10.0 / sqrt(2.0))

  test "negative speed reverses the velocity":
    let v = enemyVelocity(0.0, -5.0)
    check close(v.vx, -5.0)
    check close(v.vy, 0.0)

  test "explicitly differs from the classic sin/cos swap":
    # The old (buggy) decomposition. If the implementation ever matches this
    # at a heading where cos != sin, the test fails.
    for heading in [30.0, 60.0, 90.0, 120.0]:
      let v = enemyVelocity(heading, 8.0)
      let swappedX = sin(degToRad(heading)) * 8.0
      let swappedY = cos(degToRad(heading)) * 8.0
      check not (close(v.vx, swappedX) and close(v.vy, swappedY))