// camera.js
import {mat4Ortho, mat4LookAt, mat4Multiply} from './math.js';

export class Camera {
    constructor(element, onChangeCallback) {
        this.element = element;
        this.onChange = onChangeCallback;

        this.target = [0.5, 0, 0.5];
        this.radius = 4;
        this.theta = 135;
        this.phi = 30;

        this.projMatrix = new Float32Array(16);
        this.viewMatrix = new Float32Array(16);
        this.viewProjMatrix = new Float32Array(16);

        this.isDragging = false;
        this.dragButton = 0;
        this.touchMode = '';
        this.lastMouse = {x: 0, y: 0};
        this.lastPinchDist = 0;

        this.attachEvents();
    }

    saveState() {
        this.checkpoint = {
            target: [...this.target],
            radius: this.radius,
            theta: this.theta,
            phi: this.phi,
        }
    }

    loadState() {
        if (!this.checkpoint) return;
        this.target = [...this.checkpoint.target];
        this.radius = this.checkpoint.radius;
        this.theta = this.checkpoint.theta;
        this.phi = this.checkpoint.phi;
        this.onChange();
    }

    // --- INTERACTION MATH ---

    orbit(dx, dy) {
        this.theta -= dx * 0.4;
        this.phi += dy * 0.4;
        this.phi = Math.max(-90, Math.min(90, this.phi));
    }

    pan(dx, dy) {
        const t = this.theta * Math.PI / 180;
        const p = this.phi * Math.PI / 180;

        const rightX = Math.cos(t);
        const rightZ = -Math.sin(t);

        const upX = -Math.sin(p) * Math.sin(t);
        const upY = Math.cos(p);
        const upZ = -Math.sin(p) * Math.cos(t);

        const panSpeed = this.radius * 0.0025;

        this.target[0] += (-rightX * dx + upX * dy) * panSpeed;
        this.target[1] += (upY * dy) * panSpeed;
        this.target[2] += (-rightZ * dx + upZ * dy) * panSpeed;
    }

    zoom(delta) {
        this.radius += delta * 0.05;
        this.radius = Math.max(1, Math.min(50, this.radius));
    }

    // --- EVENT LISTENERS ---

    attachEvents() {
        this.element.addEventListener('contextmenu', e => e.preventDefault());

        // --- MOUSE EVENTS ---
        this.element.addEventListener('mousedown', (e) => {
            e.preventDefault();
            this.isDragging = true;
            this.lastMouse = {x: e.clientX, y: e.clientY};

            // Base button
            this.dragButton = e.button;

            // Modifier Overrides (Accessibility)
            if (this.dragButton === 0) {
                if (e.ctrlKey || e.metaKey) this.dragButton = 2; // Ctrl = Zoom
                else if (e.shiftKey) this.dragButton = 1;        // Shift = Pan
            }

            if (this.dragButton === 1) this.element.style.cursor = 'move';
            else if (this.dragButton === 2) this.element.style.cursor = 'ns-resize';
            else this.element.style.cursor = 'grabbing';
        });

        window.addEventListener('mouseup', () => {
            this.isDragging = false;
            this.element.style.cursor = 'grab';
        });

        window.addEventListener('mousemove', (e) => {
            if (!this.isDragging) return;
            const dx = e.clientX - this.lastMouse.x;
            const dy = e.clientY - this.lastMouse.y;
            this.lastMouse = {x: e.clientX, y: e.clientY};

            if (this.dragButton === 0) this.orbit(dx, dy);
            else if (this.dragButton === 1) this.pan(dx, dy);
            else if (this.dragButton === 2) this.zoom(dy);

            this.onChange();
        });

        // --- TOUCH EVENTS ---
        this.element.addEventListener('touchstart', (e) => {
            e.preventDefault(); // Prevents mobile browser pull-to-refresh / page scrolling
            this.isDragging = true;

            if (e.touches.length === 1) {
                this.touchMode = 'orbit';
                this.lastMouse = {x: e.touches[0].clientX, y: e.touches[0].clientY};
            } else if (e.touches.length >= 2) {
                this.touchMode = 'pan-zoom';
                const t1 = e.touches[0], t2 = e.touches[1];
                this.lastMouse = {
                    x: (t1.clientX + t2.clientX) / 2,
                    y: (t1.clientY + t2.clientY) / 2
                };
                this.lastPinchDist = Math.hypot(t1.clientX - t2.clientX, t1.clientY - t2.clientY);
            }
        }, {passive: false});

        this.element.addEventListener('touchmove', (e) => {
            if (!this.isDragging) return;
            e.preventDefault();

            if (this.touchMode === 'orbit' && e.touches.length === 1) {
                const dx = e.touches[0].clientX - this.lastMouse.x;
                const dy = e.touches[0].clientY - this.lastMouse.y;
                this.lastMouse = {x: e.touches[0].clientX, y: e.touches[0].clientY};

                this.orbit(dx, dy);
                this.onChange();
            } else if (this.touchMode === 'pan-zoom' && e.touches.length >= 2) {
                const t1 = e.touches[0], t2 = e.touches[1];
                const cx = (t1.clientX + t2.clientX) / 2;
                const cy = (t1.clientY + t2.clientY) / 2;
                const dist = Math.hypot(t1.clientX - t2.clientX, t1.clientY - t2.clientY);

                const dx = cx - this.lastMouse.x;
                const dy = cy - this.lastMouse.y;
                const dDist = dist - this.lastPinchDist; // Positive if spreading fingers

                this.lastMouse = {x: cx, y: cy};
                this.lastPinchDist = dist;

                this.pan(dx, dy);
                this.zoom(-dDist); // Pinching out zooms in
                this.onChange();
            }
        }, {passive: false});

        const onTouchEnd = (e) => {
            if (e.touches.length === 0) {
                this.isDragging = false;
            } else if (e.touches.length === 1) {
                // Seamlessly fall back to orbit if one finger is lifted
                this.touchMode = 'orbit';
                this.lastMouse = {x: e.touches[0].clientX, y: e.touches[0].clientY};
            }
        };

        this.element.addEventListener('touchend', onTouchEnd);
        this.element.addEventListener('touchcancel', onTouchEnd);
    }

    updateMatrices(aspectRatio) {
        // ... (Keep existing updateMatrices code exactly as it is) ...
        const t = this.theta * Math.PI / 180;
        const p = this.phi * Math.PI / 180;

        const eyeX = this.target[0] + this.radius * Math.cos(p) * Math.sin(t);
        const eyeY = this.target[1] + this.radius * Math.sin(p);
        const eyeZ = this.target[2] + this.radius * Math.cos(p) * Math.cos(t);

        const upX = -Math.sin(p) * Math.sin(t);
        const upY = Math.cos(p);
        const upZ = -Math.sin(p) * Math.cos(t);

        const size = this.radius * 0.5;
        mat4Ortho(this.projMatrix, -size * aspectRatio, size * aspectRatio, -size, size, -50, 50);

        mat4LookAt(this.viewMatrix, eyeX, eyeY, eyeZ, this.target[0], this.target[1], this.target[2], upX, upY, upZ);
        mat4Multiply(this.viewProjMatrix, this.projMatrix, this.viewMatrix);

        return this.viewProjMatrix;
    }
}