Mainline/engine/camera.py

"""
Camera system for viewport scrolling.

Provides abstraction for camera motion in different modes:
- Vertical: traditional upward scroll
- Horizontal: left/right movement
- Omni: combination of both
- Floating: sinusoidal/bobbing motion

The camera defines a visible viewport into a larger Canvas.
"""

import math
from collections.abc import Callable
from dataclasses import dataclass, field
from enum import Enum, auto


class CameraMode(Enum):
    VERTICAL = auto()
    HORIZONTAL = auto()
    OMNI = auto()
    FLOATING = auto()
    BOUNCE = auto()


@dataclass
class CameraViewport:
    """Represents the visible viewport."""

    x: int
    y: int
    width: int
    height: int


@dataclass
class Camera:
    """Camera for viewport scrolling.

    The camera defines a visible viewport into a Canvas.
    It can be smaller than the canvas to allow scrolling,
    and supports zoom to scale the view.

    Attributes:
        x: Current horizontal offset (positive = scroll left)
        y: Current vertical offset (positive = scroll up)
        mode: Current camera mode
        speed: Base scroll speed
        zoom: Zoom factor (1.0 = 100%, 2.0 = 200% zoom out)
        canvas_width: Width of the canvas being viewed
        canvas_height: Height of the canvas being viewed
        custom_update: Optional custom update function
    """

    x: int = 0
    y: int = 0
    mode: CameraMode = CameraMode.VERTICAL
    speed: float = 1.0
    zoom: float = 1.0
    canvas_width: int = 200  # Larger than viewport for scrolling
    canvas_height: int = 200
    custom_update: Callable[["Camera", float], None] | None = None
    _time: float = field(default=0.0, repr=False)

    @property
    def w(self) -> int:
        """Shorthand for viewport_width."""
        return self.viewport_width

    @property
    def h(self) -> int:
        """Shorthand for viewport_height."""
        return self.viewport_height

    @property
    def viewport_width(self) -> int:
        """Get the visible viewport width.

        This is the canvas width divided by zoom.
        """
        return max(1, int(self.canvas_width / self.zoom))

    @property
    def viewport_height(self) -> int:
        """Get the visible viewport height.

        This is the canvas height divided by zoom.
        """
        return max(1, int(self.canvas_height / self.zoom))

    def get_viewport(self) -> CameraViewport:
        """Get the current viewport bounds.

        Returns:
            CameraViewport with position and size (clamped to canvas bounds)
        """
        vw = self.viewport_width
        vh = self.viewport_height

        clamped_x = max(0, min(self.x, self.canvas_width - vw))
        clamped_y = max(0, min(self.y, self.canvas_height - vh))

        return CameraViewport(
            x=clamped_x,
            y=clamped_y,
            width=vw,
            height=vh,
        )

    def set_zoom(self, zoom: float) -> None:
        """Set the zoom factor.

        Args:
            zoom: Zoom factor (1.0 = 100%, 2.0 = zoomed out 2x, 0.5 = zoomed in 2x)
        """
        self.zoom = max(0.1, min(10.0, zoom))

    def update(self, dt: float) -> None:
        """Update camera position based on mode.

        Args:
            dt: Delta time in seconds
        """
        self._time += dt

        if self.custom_update:
            self.custom_update(self, dt)
            return

        if self.mode == CameraMode.VERTICAL:
            self._update_vertical(dt)
        elif self.mode == CameraMode.HORIZONTAL:
            self._update_horizontal(dt)
        elif self.mode == CameraMode.OMNI:
            self._update_omni(dt)
        elif self.mode == CameraMode.FLOATING:
            self._update_floating(dt)
        elif self.mode == CameraMode.BOUNCE:
            self._update_bounce(dt)

        # Bounce mode handles its own bounds checking
        if self.mode != CameraMode.BOUNCE:
            self._clamp_to_bounds()

    def _clamp_to_bounds(self) -> None:
        """Clamp camera position to stay within canvas bounds.

        Only clamps if the viewport is smaller than the canvas.
        If viewport equals canvas (no scrolling needed), allows any position
        for backwards compatibility with original behavior.
        """
        vw = self.viewport_width
        vh = self.viewport_height

        # Only clamp if there's room to scroll
        if vw < self.canvas_width:
            self.x = max(0, min(self.x, self.canvas_width - vw))
        if vh < self.canvas_height:
            self.y = max(0, min(self.y, self.canvas_height - vh))

    def _update_vertical(self, dt: float) -> None:
        self.y += int(self.speed * dt * 60)

    def _update_horizontal(self, dt: float) -> None:
        self.x += int(self.speed * dt * 60)

    def _update_omni(self, dt: float) -> None:
        speed = self.speed * dt * 60
        self.y += int(speed)
        self.x += int(speed * 0.5)

    def _update_floating(self, dt: float) -> None:
        base = self.speed * 30
        self.y = int(math.sin(self._time * 2) * base)
        self.x = int(math.cos(self._time * 1.5) * base * 0.5)

    def _update_bounce(self, dt: float) -> None:
        """Bouncing DVD-style camera that bounces off canvas edges."""
        vw = self.viewport_width
        vh = self.viewport_height

        # Initialize direction if not set
        if not hasattr(self, "_bounce_dx"):
            self._bounce_dx = 1
            self._bounce_dy = 1

        # Calculate max positions
        max_x = max(0, self.canvas_width - vw)
        max_y = max(0, self.canvas_height - vh)

        # Move
        move_speed = self.speed * dt * 60

        # Bounce off edges - reverse direction when hitting bounds
        self.x += int(move_speed * self._bounce_dx)
        self.y += int(move_speed * self._bounce_dy)

        # Bounce horizontally
        if self.x <= 0:
            self.x = 0
            self._bounce_dx = 1
        elif self.x >= max_x:
            self.x = max_x
            self._bounce_dx = -1

        # Bounce vertically
        if self.y <= 0:
            self.y = 0
            self._bounce_dy = 1
        elif self.y >= max_y:
            self.y = max_y
            self._bounce_dy = -1

    def reset(self) -> None:
        """Reset camera position."""
        self.x = 0
        self.y = 0
        self._time = 0.0
        self.zoom = 1.0

    def set_canvas_size(self, width: int, height: int) -> None:
        """Set the canvas size and clamp position if needed.

        Args:
            width: New canvas width
            height: New canvas height
        """
        self.canvas_width = width
        self.canvas_height = height
        self._clamp_to_bounds()

    @classmethod
    def vertical(cls, speed: float = 1.0) -> "Camera":
        """Create a vertical scrolling camera."""
        return cls(mode=CameraMode.VERTICAL, speed=speed, canvas_height=200)

    @classmethod
    def horizontal(cls, speed: float = 1.0) -> "Camera":
        """Create a horizontal scrolling camera."""
        return cls(mode=CameraMode.HORIZONTAL, speed=speed, canvas_width=200)

    @classmethod
    def omni(cls, speed: float = 1.0) -> "Camera":
        """Create an omnidirectional scrolling camera."""
        return cls(
            mode=CameraMode.OMNI, speed=speed, canvas_width=200, canvas_height=200
        )

    @classmethod
    def floating(cls, speed: float = 1.0) -> "Camera":
        """Create a floating/bobbing camera."""
        return cls(
            mode=CameraMode.FLOATING, speed=speed, canvas_width=200, canvas_height=200
        )

    @classmethod
    def bounce(cls, speed: float = 1.0) -> "Camera":
        """Create a bouncing DVD-style camera that bounces off canvas edges."""
        return cls(
            mode=CameraMode.BOUNCE, speed=speed, canvas_width=200, canvas_height=200
        )

    @classmethod
    def custom(cls, update_fn: Callable[["Camera", float], None]) -> "Camera":
        """Create a camera with custom update function."""
        return cls(custom_update=update_fn)