// FILE: lib/game/Camera.ts

import { lerp } from "../utils";

interface Target {
    x: number;
    y: number;
    width: number;
    height: number;
}

export class Camera {
    // Current camera properties
    x: number;
    y: number;
    zoom: number = 1;

    // Target properties for smooth transitions
    private targetX: number;
    private targetY: number;
    private targetZoom: number = 1;
    private followTarget: Target | null = null;

    // Smoothing factor for lerping
    private readonly LERP_FACTOR = 0.08;

    constructor(canvasWidth: number, canvasHeight: number) {
        this.x = canvasWidth / 2;
        this.y = canvasHeight / 2;
        this.targetX = this.x;
        this.targetY = this.y;
    }

    // --- Public methods for the sandbox API ---

    panTo(x: number, y: number) {
        this.followTarget = null; // Stop following any target when manually panning
        this.targetX = x;
        this.targetY = y;
    }

    setZoom(level: number) {
        this.targetZoom = Math.max(0.5, Math.min(level, 3)); // Clamp zoom level
    }
    
    focusOn(target: Target) {
        this.followTarget = target;
    }
    
    reset() {
        this.followTarget = null;
        this.targetX = 0; // Or initial canvas center
        this.targetY = 0; // Or initial canvas center
        this.targetZoom = 1;
    }

    // --- Internal update method for the game loop ---

    update() {
        if (this.followTarget) {
            this.targetX = this.followTarget.x + this.followTarget.width / 2;
            this.targetY = this.followTarget.y + this.followTarget.height / 2;
        }

        // Smoothly interpolate current values towards target values
        this.x = lerp(this.x, this.targetX, this.LERP_FACTOR);
        this.y = lerp(this.y, this.targetY, this.LERP_FACTOR);
        this.zoom = lerp(this.zoom, this.targetZoom, this.LERP_FACTOR);
    }

    // --- Method to apply transformations to the canvas context ---
    
     public applyTransform(ctx: CanvasRenderingContext2D, shake: { offsetX: number, offsetY: number }) {
        const canvasWidth = ctx.canvas.width;
        const canvasHeight = ctx.canvas.height;

        // First, move the canvas origin to the center of the screen
        ctx.translate(canvasWidth / 2, canvasHeight / 2);
        // Then, apply the zoom
        ctx.scale(this.zoom, this.zoom);
        // Finally, pan the camera to the target coordinates
        ctx.translate(-this.x, -this.y);
        
        // NEW: Apply the camera shake as the very last translation
        ctx.translate(shake.offsetX, shake.offsetY);
    }
}