"""Camera module - manages zoom and pan for a 2D viewport."""

import pygame as pg


class Camera:
    """2D camera with zoom and world/screen coordinate conversion.

    Attributes:
        zoom (float): Current zoom multiplier, clamped to [0.5, 4.0].
        offset (pg.math.Vector2): Top-left world position currently in view.
    """

    def __init__(self):
        self.zoom = 2
        self.offset = pg.math.Vector2(0, 0)

    def world_to_screen(self, pos):
        """Convert a world-space position to screen pixels."""
        return (
            int((pos[0] - self.offset.x) * self.zoom),
            int((pos[1] - self.offset.y) * self.zoom),
        )

    def screen_to_world(self, pos):
        """Convert a screen pixel position to world-space coordinates."""
        return (
            pos[0] / self.zoom + self.offset.x,
            pos[1] / self.zoom + self.offset.y,
        )

    def move(self, dx, dy):
        """Pan the camera by (dx, dy) in world-space units."""
        self.offset.x += dx
        self.offset.y += dy

    def change_zoom(self, amount):
        """Adjust zoom by amount, clamped to [0.5, 4.0]."""
        self.zoom += amount
        self.zoom = max(0.5, min(self.zoom, 4.0))

    def zoom_offset(self, screen_pos, zoom_factor):
        """Zoom toward screen_pos, keeping the world point under it stationary."""
        world_before = self.screen_to_world(screen_pos)
        self.change_zoom(zoom_factor)
        world_after = self.screen_to_world(screen_pos)

        # Compensate offset so the point under the cursor doesn't shift
        self.offset.x += world_before[0] - world_after[0]
        self.offset.y += world_before[1] - world_after[1]