"""Pinball physics: pure logic, no rendering. Testable headless.

Coordinate system: y grows downward. 480x360 virtual canvas.
"""

import math
import random

# ---------------------------------------------------------------------------
# Playfield geometry
# ---------------------------------------------------------------------------
CV_W, CV_H = 480, 360
PLAY_L, PLAY_R, PLAY_T, PLAY_B = 20.0, 460.0, 52.0, 346.0

GRAVITY = 0.24            # px/frame^2
MAX_SPEED = 13.0          # speed cap (prevents tunneling; ~300px of rise)
RESTITUTION = 0.42
BALL_R = 7.0

FLIP_LEN = 154.0
FLIP_REST = math.radians(6.0)      # tips slightly lowered toward center drain
FLIP_UP = -math.radians(52.0)      # fired position
FLIP_PIVOT_L = (62.0, 338.0)
FLIP_PIVOT_R = (418.0, 338.0)
FLIP_RADIUS = 5.5
FLIP_SNAP_UP = 0.36                # rad/frame while firing
FLIP_SNAP_DOWN = 0.05              # gentle return speed
FLIP_BOUNCE = 0.12

# elements
BUMPERS = [
    dict(pos=(150.0, 180.0), r=23.0, color="pink"),
    dict(pos=(330.0, 180.0), r=23.0, color="mint"),
    dict(pos=(240.0, 240.0), r=23.0, color="lemon"),
]
SLING_KICK_L = (0.60, -0.80)
SLING_KICK_R = (-0.60, -0.80)
SLINGS = [
    # upper slingshots just below the two outer bumpers - kick toward centre
    dict(pos=(150.0, 282.0), r=11.0, kick=SLING_KICK_L),
    dict(pos=(330.0, 282.0), r=11.0, kick=SLING_KICK_R),
    # guard posts at the outlane mouths: wall-huggers get bounced back into
    # play instead of silently draining - the centre gap is the real risk
    dict(pos=(44.0, 314.0), r=12.0, kick=(0.80, -0.60)),
    dict(pos=(436.0, 314.0), r=12.0, kick=(-0.80, -0.60)),
]
STARS = [(168.0, 92.0), (240.0, 92.0), (312.0, 92.0)]

CANNON = (440.0, 152.0)
CANNON_R = 17.0
LAUNCH_DIR = (-0.94, -0.34)
LAUNCH_MIN, LAUNCH_MAX = 7.0, 13.5

DRAIN_Y = 362.0
CENTER_HOLE = (200.0, 280.0)
OUTLANE_L = 46.0
OUTLANE_R = 434.0


def clamp(v, lo, hi):
    return lo if v < lo else hi if v > hi else v


def seg_info(px, py, ax, ay, bx, by):
    """Closest point on segment ab to p; returns (t, cx, cy, dist2)."""
    abx, aby = bx - ax, by - ay
    l2 = abx * abx + aby * aby
    if l2 == 0.0:
        return 0.0, ax, ay, (px - ax) ** 2 + (py - ay) ** 2
    t = clamp(((px - ax) * abx + (py - ay) * aby) / l2, 0.0, 1.0)
    cx, cy = ax + abx * t, ay + aby * t
    dx, dy = px - cx, py - cy
    return t, cx, cy, dx * dx + dy * dy


def flipper_tip(f):
    """World-space position of the flipper tip.

    Angles are expressed in *local* coordinates: a positive angle lowers the
    tip toward the centre drain (screen-down is +y). The right flipper is the
    mirror image of the left, so its horizontal component is negated.
    """
    px, py = f["pivot"]
    a = f["angle"]
    if f["side"] == "L":
        return (px + math.cos(a) * f["length"], py + math.sin(a) * f["length"])
    return (px - math.cos(a) * f["length"], py + math.sin(a) * f["length"])


class Ball:
    __slots__ = ("x", "y", "vx", "vy", "rad", "prev_x", "prev_y")

    def __init__(self, x, y):
        self.x, self.y = float(x), float(y)
        self.vx = self.vy = 0.0
        self.rad = BALL_R
        self.prev_x, self.prev_y = x, y

    @property
    def speed(self):
        return math.hypot(self.vx, self.vy)


class Event:
    __slots__ = ("kind", "x", "y", "data")

    def __init__(self, kind, x=0.0, y=0.0, data=None):
        self.kind, self.x, self.y, self.data = kind, x, y, data

    def __repr__(self):
        return "Event(%s)" % self.kind


class Table:
    def __init__(self, seed=1):
        self.rng = random.Random(seed)
        self.events = []
        self.frame = 0

        # static walls / floors: list of (a, b, kind) where kind in
        # ("rail", "floor") - rails keep balls in, floors hold them up
        self.walls = [
            ((PLAY_L, PLAY_T), (PLAY_L, PLAY_B), "rail"),
            ((PLAY_R, PLAY_T), (PLAY_R, PLAY_B), "rail"),
            ((PLAY_L, PLAY_T), (PLAY_R, PLAY_T), "rail"),
            # floors tilt gently down toward the center so balls funnel inward
            ((OUTLANE_L, PLAY_B - 8), (CENTER_HOLE[0], PLAY_B), "floor"),
            ((CENTER_HOLE[1], PLAY_B), (OUTLANE_R, PLAY_B - 8), "floor"),
            ((CENTER_HOLE[0], PLAY_B), (CENTER_HOLE[0], DRAIN_Y), "hole"),
            ((CENTER_HOLE[1], PLAY_B), (CENTER_HOLE[1], DRAIN_Y), "hole"),
            ((OUTLANE_L, PLAY_B), (OUTLANE_L, DRAIN_Y), "hole"),
            ((OUTLANE_R, PLAY_B), (OUTLANE_R, DRAIN_Y), "hole"),
        ]

        self.bumpers = [
            dict(x=b["pos"][0], y=b["pos"][1], r=b["r"], color=b["color"],
                 cool=0, hit=0, squash=0, face_t=0.0, blink=0.0)
            for b in BUMPERS]
        self.slings = [
            dict(x=s["pos"][0], y=s["pos"][1], r=s["r"], cool=0, flash=0,
                 kick=s["kick"])
            for i, s in enumerate(SLINGS)]
        self.stars = [dict(x=x, y=y, r=13.0, lit=False, cool=0, pulse=0)
                      for x, y in STARS]
        self.flippers = [
            dict(side="L", pivot=FLIP_PIVOT_L, angle=FLIP_REST, rest=FLIP_REST,
                 up=FLIP_UP, length=FLIP_LEN, pressed=False, w=0.0, contacting=False),
            dict(side="R", pivot=FLIP_PIVOT_R, angle=FLIP_REST, rest=FLIP_REST,
                 up=FLIP_UP, length=FLIP_LEN, pressed=False, w=0.0, contacting=False),
        ]
        for f in self.flippers:
            f["prev_tip"] = flipper_tip(f)
            f["tipvx"] = f["tipvy"] = 0.0
        self.cannon = dict(x=CANNON[0], y=CANNON[1], r=CANNON_R)

        self.ball = Ball(CANNON[0], CANNON[1])
        self.ball_live = False
        self.charge = 0.0
        self.stuck_frames = 0
        self.trail = []

    # ------------------------------------------------------------- input
    def press(self, side, down):
        f = self.flippers[0] if side == "L" else self.flippers[1]
        f["pressed"] = down

    # ------------------------------------------------------------- setup
    def reset_ball_in_cannon(self):
        self.charge = 0.0
        self.ball_live = False
        self.ball.x, self.ball.y = CANNON[0] + 6, CANNON[1]
        self.ball.vx = self.ball.vy = 0.0
        self.ball.prev_x, self.ball.prev_y = self.ball.x, self.ball.y
        self.stuck_frames = 0
        self.trail = []

    def launch(self, power):
        self.ball_live = True
        mx, my = CANNON
        off = CANNON_R + self.ball.rad + 2.0
        self.ball.x = mx + LAUNCH_DIR[0] * off
        self.ball.y = my + LAUNCH_DIR[1] * off
        self.ball.vx = LAUNCH_DIR[0] * power
        self.ball.vy = LAUNCH_DIR[1] * power
        self.ball.prev_x, self.ball.prev_y = self.ball.x, self.ball.y
        self.trail = [(self.ball.x, self.ball.y)]
        return Event("launch", self.ball.x, self.ball.y)

    # ------------------------------------------------------------- frame
    def update(self):
        self.events = []
        self.frame += 1

        # decay timers
        for b in self.bumpers:
            if b["cool"] > 0:
                b["cool"] -= 1
            if b["squash"] > 0:
                b["squash"] -= 1
            b["face_t"] += 1
            if b["blink"] > 0:
                b["blink"] -= 1
            elif self.rng.random() < 0.0025:
                b["blink"] = 16
        for s in self.slings:
            if s["cool"] > 0:
                s["cool"] -= 1
            if s["flash"] > 0:
                s["flash"] -= 1
        for st in self.stars:
            if st["cool"] > 0:
                st["cool"] -= 1
            if st["pulse"] > 0:
                st["pulse"] -= 1

        if not self.ball_live:
            return self.events
        if self.ball.y > DRAIN_Y + 30 and not self._in_drain(self.ball.x, self.ball.y):
            # lost below the table somehow - force a drain
            self.events.append(Event("drain", self.ball.x, self.ball.y))
            return self.events

        ball = self.ball

        # flippers move inside substeps; sweep 6 steps/frame while pressed so
        # the paddle never jumps over a resting ball
        flips_moving = any(f["pressed"] for f in self.flippers)
        speed = ball.speed
        n_sub = 6 if flips_moving else 1
        if speed > 0.0:
            n_sub = max(n_sub, min(6, int(math.ceil(speed / 4.0))))
        for _ in range(n_sub):
            self._substep(ball, 1.0 / n_sub, n_sub)

        self.trail.append((ball.x, ball.y))
        if len(self.trail) > 9:
            self.trail.pop(0)

        if ball.speed < 0.55:
            self.stuck_frames += 1
            if self.stuck_frames > 60 and self.stuck_frames % 14 == 0:
                ang = self.rng.uniform(0.0, math.tau)
                ball.vx += math.cos(ang) * 1.3
                ball.vy += math.sin(ang) * 1.3 - 1.1
                self.events.append(Event("nudge", ball.x, ball.y))
        else:
            self.stuck_frames = 0

        if self._in_drain(ball.x, ball.y):
            self.events.append(Event("drain", ball.x, ball.y))
        return self.events

    # ------------------------------------------------------------- helpers
    def _in_drain(self, x, y):
        if y < DRAIN_Y - 2:
            return False
        if CENTER_HOLE[0] - 6 < x < CENTER_HOLE[1] + 6:
            return True
        if x < OUTLANE_L - 4 or x > OUTLANE_R + 4:
            return True
        if y > DRAIN_Y + 8:
            return x < OUTLANE_L + 10 or x > OUTLANE_R - 10
        return False

    # ------------------------------------------------------------- substep
    def _substep(self, ball, dt, n_sub=1):
        # flippers: kinematic angles advance inside the substep so a fast sweep
        # stays continuous w.r.t. the ball (no tunneling past a resting ball).
        for f in self.flippers:
            target = f["up"] if f["pressed"] else f["rest"]
            rate = (FLIP_SNAP_UP if f["pressed"] else FLIP_SNAP_DOWN) * dt
            d = target - f["angle"]
            f["angle"] = target if abs(d) < rate else f["angle"] + (rate if d > 0 else -rate)
            tip = flipper_tip(f)
            fx, fy = f["prev_tip"]
            # displacement this substep, scaled back to px/frame
            f["tipvx"] = (tip[0] - fx) * n_sub
            f["tipvy"] = (tip[1] - fy) * n_sub
            f["prev_tip"] = tip
            f["contacting"] = False

        ball.vy += GRAVITY * dt
        ball.vx *= (1.0 - 0.014 * dt)
        ball.vy *= (1.0 - 0.005 * dt)
        ball.prev_x, ball.prev_y = ball.x, ball.y
        ball.x += ball.vx * dt
        ball.y += ball.vy * dt

        # static walls / floors
        for (ax, ay), (bx, by), kind in self.walls:
            t, cx, cy, d2 = seg_info(ball.x, ball.y, ax, ay, bx, by)
            if d2 >= ball.rad * ball.rad:
                continue
            if t <= 0.0 or t >= 1.0:
                continue
            dist = math.sqrt(d2)
            nx = (ball.x - cx) / dist
            ny = (ball.y - cy) / dist
            # one-way-ish: never fling a ball that has dropped past a floor plane
            if kind == "floor" and ball.y > PLAY_B + ball.rad * 0.5 and ny < -0.3:
                continue
            ball.x = cx + nx * ball.rad
            ball.y = cy + ny * ball.rad
            vn = ball.vx * nx + ball.vy * ny
            if vn < 0.0:
                e = RESTITUTION if kind == "floor" else 0.5
                ball.vx -= (1.0 + e) * vn * nx
                ball.vy -= (1.0 + e) * vn * ny
            ball.vx *= 0.985
            if kind == "rail" and ball.speed > 8.0:
                self.events.append(Event("wall_hit", ball.x, ball.y, ball.speed))

        # bumpers
        for b in self.bumpers:
            self._bumper_collide(ball, b)

        # slingshots
        for s in self.slings:
            self._sling_collide(ball, s)

        # flippers
        for f in self.flippers:
            self._flipper_collide(ball, f)

        # cannon deflector
        self._circle_push(ball, self.cannon["x"], self.cannon["y"],
                          self.cannon["r"], 0.5)

        # star lanes
        for st in self.stars:
            dx = ball.x - st["x"]
            dy = ball.y - st["y"]
            rr = st["r"] + ball.rad
            if dx * dx + dy * dy < rr * rr and st["cool"] <= 0:
                st["cool"] = 26
                st["pulse"] = 14
                if not st["lit"]:
                    st["lit"] = True
                    self.events.append(Event("star_lit", st["x"], st["y"], st))
                else:
                    self.events.append(Event("star_again", st["x"], st["y"], st))

        self._cap(ball)

    @staticmethod
    def _cap(ball):
        sp = ball.speed
        if sp > MAX_SPEED:
            k = MAX_SPEED / sp
            ball.vx *= k
            ball.vy *= k

    def _circle_push(self, ball, cx, cy, cr, e, impulse=None, cool_key=None):
        """Generic circle collider. impulse=(ix,iy,strength) overrides bounce."""
        dx = ball.x - cx
        dy = ball.y - cy
        rr = cr + ball.rad
        d2 = dx * dx + dy * dy
        if d2 >= rr * rr or d2 < 0.0001:
            return False
        d = math.sqrt(d2)
        nx, ny = dx / d, dy / d
        ball.x = cx + nx * rr
        ball.y = cy + ny * rr
        if impulse is not None:
            kx, ky, sp = impulse
            ball.vx = kx * sp
            ball.vy = ky * sp
            return True
        vn = ball.vx * nx + ball.vy * ny
        if vn < 0.0:
            ball.vx -= (1.0 + e) * vn * nx
            ball.vy -= (1.0 + e) * vn * ny
        return True

    def _bumper_collide(self, ball, b):
        dx = ball.x - b["x"]
        dy = ball.y - b["y"]
        rr = b["r"] + ball.rad
        d2 = dx * dx + dy * dy
        if d2 >= rr * rr or d2 < 0.0001:
            return
        d = math.sqrt(d2)
        nx, ny = dx / d, dy / d
        ball.x = b["x"] + nx * rr
        ball.y = b["y"] + ny * rr
        if b["cool"] > 0:
            return
        b["cool"] = 6
        b["hit"] += 1
        b["squash"] = 5
        b["face_t"] = 0.0
        kick = max(6.0, ball.speed * 0.72 + 4.2)
        ball.vx = nx * kick
        ball.vy = ny * kick
        self.events.append(Event("bumper", b["x"] + nx * b["r"], b["y"] + ny * b["r"], b))

    def _sling_collide(self, ball, s):
        dx = ball.x - s["x"]
        dy = ball.y - s["y"]
        rr = s["r"] + ball.rad
        d2 = dx * dx + dy * dy
        if d2 >= rr * rr or d2 < 0.0001:
            return
        d = math.sqrt(d2)
        nx, ny = dx / d, dy / d
        ball.x = s["x"] + nx * rr
        ball.y = s["y"] + ny * rr
        if s["cool"] > 0:
            return
        s["cool"] = 4
        s["flash"] = 7
        kx, ky = s["kick"]
        ball.vx = kx * 9.6
        ball.vy = ky * 9.6
        self.events.append(Event("sling", s["x"] + kx * 22, s["y"] + ky * 22, s))

    def _flipper_collide(self, ball, f):
        px, py = f["pivot"]
        tipx, tipy = flipper_tip(f)
        t, cx, cy, d2 = seg_info(ball.x, ball.y, px, py, tipx, tipy)
        rad = FLIP_RADIUS + ball.rad
        if d2 >= rad * rad:
            return
        # endpoint (pivot) -> small circle collider; tip end -> still a segment
        if t <= 0.0 or t >= 1.0:
            ex, ey = (px, py) if t <= 0.0 else (tipx, tipy)
            exx, eyy = ball.x - ex, ball.y - ey
            ed = math.hypot(exx, eyy)
            if ed < rad:
                nx, ny = exx / ed, eyy / ed
                ball.x = ex + nx * rad
                ball.y = ey + ny * rad
                self._flipper_impulse(ball, f, nx, ny)
            return
        dist = math.sqrt(d2)
        nx = (ball.x - cx) / dist
        ny = (ball.y - cy) / dist
        ball.x = cx + nx * rad
        ball.y = cy + ny * rad
        self._flipper_impulse(ball, f, nx, ny)

    def _flipper_impulse(self, ball, f, nx, ny):
        """Reflect relative velocity across the moving flipper surface.

        sv = the velocity of the flipper surface at the contact point. The tip
        moves by (tipvx, tipvy) px/frame; points closer to the pivot move
        proportionally less, so scale by the contact radius / length.
        """
        px, py = f["pivot"]
        rx, ry = ball.x - px, ball.y - py
        rc = math.hypot(rx, ry)
        scale = 1.0 if f["length"] <= 0 else min(1.0, max(0.2, rc / f["length"]))
        svx = f["tipvx"] * scale
        svy = f["tipvy"] * scale
        rvx = ball.vx - svx
        rvy = ball.vy - svy
        vn = rvx * nx + rvy * ny

        fresh = not f["contacting"]
        f["contacting"] = True
        if vn < -0.9:
            if fresh:
                j = -(1.0 + FLIP_BOUNCE) * vn
            else:
                j = -vn  # inelastic follow-through while pressing
            ball.vx += j * nx
            ball.vy += j * ny
        # light tangential traction so resting balls ride the swipe a little
        tx, ty = -ny, nx
        vt = rvx * tx + rvy * ty
        traction = 0.18 if (abs(f["tipvx"]) + abs(f["tipvy"])) > 0.1 else 0.0
        ball.vx -= traction * vt * tx
        ball.vy -= traction * vt * ty
        self._cap(ball)