import { vec3, vec4, mat4 } from 'gl-matrix';
import { Camera } from './Camera';
import { ProjectedOcean } from './OceanLOD';
import { Skybox } from './Skybox';
import { createProgram } from './Shader';
import * as Config from './constants';

var gl: WebGL2RenderingContext;
var viewportWidth = 0;
var viewportHeight = 0;

/** A camera that always looks at the world origin. Can have an offset and be rotated. */
// Moved to Camera.ts

/** Init OpenGL and gets the viewport/canvas sizes */
function initGL(canvas: HTMLCanvasElement) {
    // Helper function for canvas resize
    const updateCanvasSize = (canvas: HTMLCanvasElement) => {
        const displayWidth = window.innerWidth;
        const displayHeight = window.innerHeight;
        
        if (canvas.width !== displayWidth || canvas.height !== displayHeight) {
            canvas.width = displayWidth;
            canvas.height = displayHeight;
            viewportWidth = displayWidth;
            viewportHeight = displayHeight;
            
            if (gl) {
                gl.viewport(0, 0, viewportWidth, viewportHeight);
            }
        }
    };

    var gltemp;
    try {
        gltemp = canvas.getContext("webgl2");
        if (!gltemp)
            gltemp = canvas.getContext("experimental-webgl2");
        if (gltemp != null) {
            updateCanvasSize(canvas);
        }

    } catch (e) {
    }
    // Not the best error detection logic.
    // Redirect to http://get.webgl.org in failure case.
    if (gltemp == null) {
        console.error("Unable to initialize WebGL2. Your browser or machine may not support it.");
        return;
    }
    gl = <WebGL2RenderingContext>gltemp;
    //WebGL2 supports floating point textures by default but it does not support filtering them or rendering to them by default. Note: 16bit filtering is included 32bit not
    if (!gl.getExtension('EXT_color_buffer_float')) {
        console.error("32Bit/16Bit single Color render Buffers not available.");
    } //allow 16bit texture as framebuffer target

    gl.enable(gl.DEPTH_TEST);
    
    return updateCanvasSize;
}

/** Update canvas size to fill window */
// Moved inline below

/** Grid for the watersurface */
// Moved to Grid.ts

/** Init Geometry for a Triangle */
var VBO: WebGLBuffer | null = null;
function initGeometry() {
    VBO = gl.createBuffer();
    //Vertex data represent fullscreen quad in NDC-Space
    // X, Y, Z, U, V
    let vertexData = [-1.0, -1.0, 0.0, /*BOTTOM LEFT*/ 0.0, 0.0,
        1.0, -1.0, 0.0, /*BOTTOM RIGHT*/ 1.0, 0.0,
    -1.0, 1.0, 0.0, /*TOP LEFT */ 0.0, 1.0,
        1.0, -1.0, 0.0, /*BOTTOM RIGHT */ 1.0, 0.0,
    -1.0, 1.0, 0.0, /*TOP LEFT */ 0.0, 1.0,
        1.0, 1.0, 0.0,  /*TOP RIGHT */ 1.0, 1.0
    ];

    gl.bindBuffer(gl.ARRAY_BUFFER, VBO);
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexData), gl.STATIC_DRAW);
}

/**  Get shader source by HTML-Element<id> */
// Moved to Shader.ts

/** Init all Shaders that are needed */
var perlinNoiseProgram: WebGLProgram | null;
var defaultProgram: WebGLProgram | null;
var textureProgram: WebGLProgram | null;
var skyProgram: WebGLProgram | null;
function initShaders() {
    perlinNoiseProgram = createProgram(gl, "ndc-vs", "noise-fs", "Perlin Noise");
    defaultProgram = createProgram(gl, "default-vs", "default-fs", "Default");
    textureProgram = createProgram(gl, "texture-vs", "texture-fs", "Texture");
    skyProgram = createProgram(gl, "sky-vs", "sky-fs", "Sky");
}

/** Init an FBO used for the first render pass / perlin noise */
var perlinNoiseFBO: WebGLFramebuffer | null = null;
var textureFBO: WebGLTexture | null = null;
var perlinNoiseFBOWidth = Config.NOISE_TEXTURE_WIDTH;
var perlinNoiseFBOHeight = Config.NOISE_TEXTURE_HEIGHT;
function initFBO() {
    perlinNoiseFBO = gl.createFramebuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, perlinNoiseFBO);

    // Add attachments
    textureFBO = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, textureFBO);                                            //last 3 parameter not intertesting becuase we are not supplying data
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.R16F, perlinNoiseFBOWidth, perlinNoiseFBOHeight, 0, gl.RED, gl.HALF_FLOAT, null);

    // set the filtering so we don't need mips
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT);

    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, textureFBO, 0);

    if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE) {
        console.log("Framebuffer creation failed.");
    }

    gl.bindFramebuffer(gl.FRAMEBUFFER, null); //Reset to default framebuffer
}

/** Update/Draw function.*/
/** Framerate measurement variables */
var timeSpent = 0.0;
var lastTime = new Date().getTime();
var counter = 0.0;
var fps = 0;
var fpsDisplay: HTMLElement | null = null;
/** Input states*/
var mouseXVel = 0;
var mouseYVel = 0;
var keysPressed: Set<string> = new Set();
/** Objects and states*/
var camera: Camera;
var projectedOcean: ProjectedOcean;
var skybox: Skybox;
var wireframeMode = false;
/** Camera movement speed */
var moveSpeed = 0.15;
var fastMoveSpeed = 0.4;
/** Ocean shader settings */
var waveHeight = 1.0;
var waveSpeed = 1.0;
var foamIntensity = 1.0;
var glitterIntensity = 1.0;
function drawScene() {
    fps++;
    let now = new Date();
    let delta = now.getTime() - lastTime;
    timeSpent += delta;
    
    if ((counter += delta) >= Config.FPS_UPDATE_INTERVAL) {
        counter = 0;
        if (fpsDisplay) {
            fpsDisplay.textContent = `FPS: ${fps}`;
        }
        fps = 0;
    }
    lastTime = now.getTime();
    
    // Sun direction (matches the one in ocean shader)
    const sunDirection = vec3.fromValues(0.3, 0.5, 0.8);
    vec3.normalize(sunDirection, sunDirection);

    //--- Render pass -> Skybox first (no depth write) ---
    {
        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
        gl.viewport(0, 0, viewportWidth, viewportHeight);
        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

        var projection = mat4.create();
        mat4.perspective(projection, Config.FOV, viewportWidth / viewportHeight, Config.NEAR_PLANE, Config.FAR_PLANE);

        // Handle FPS camera movement
        handleCameraMovement();
        
        // Apply mouse rotation
        if (mouseXVel !== 0 || mouseYVel !== 0) {
            camera.rotate(mouseXVel, mouseYVel);
            mouseXVel = 0;
            mouseYVel = 0;
        }
        
        var view = camera.getViewMatrix();

        // Draw skybox first with depth test disabled (always behind everything)
        gl.depthMask(false);
        gl.disable(gl.DEPTH_TEST);
        gl.useProgram(skyProgram);
        
        let sky_view_loc = gl.getUniformLocation(<WebGLProgram>skyProgram, "view");
        gl.uniformMatrix4fv(sky_view_loc, false, view);
        let sky_projection_loc = gl.getUniformLocation(<WebGLProgram>skyProgram, "projection");
        gl.uniformMatrix4fv(sky_projection_loc, false, projection);
        let sky_sun_loc = gl.getUniformLocation(<WebGLProgram>skyProgram, "uSunDirection");
        gl.uniform3fv(sky_sun_loc, sunDirection);
        
        skybox.draw(gl);
        gl.enable(gl.DEPTH_TEST);
        gl.depthMask(true);

        // Update projected ocean's projector matrices
        projectedOcean.updateProjector(camera.pos, camera.forward, view, projection);

        gl.useProgram(defaultProgram);
        let view_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "view");
        gl.uniformMatrix4fv(view_loc, false, view);
        let projection_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "projection");
        gl.uniformMatrix4fv(projection_loc, false, projection);
        let projectorMatrix_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "uProjectorMatrix");
        gl.uniformMatrix4fv(projectorMatrix_loc, false, projectedOcean.projectorMatrix);
        let rangeMatrix_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "uRangeMatrix");
        gl.uniformMatrix4fv(rangeMatrix_loc, false, projectedOcean.rangeMatrix);
        let eye_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "eyePos");
        gl.uniform3fv(eye_loc, camera.pos);
        let uTime_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "uTime");
        gl.uniform1f(uTime_loc, timeSpent);
        
        // Ocean shader settings
        let uWaveHeight_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "uWaveHeight");
        gl.uniform1f(uWaveHeight_loc, waveHeight);
        let uWaveSpeed_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "uWaveSpeed");
        gl.uniform1f(uWaveSpeed_loc, waveSpeed);
        let uFoamIntensity_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "uFoamIntensity");
        gl.uniform1f(uFoamIntensity_loc, foamIntensity);
        let uGlitterIntensity_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "uGlitterIntensity");
        gl.uniform1f(uGlitterIntensity_loc, glitterIntensity);
        
        // Calculate horizon Y in clip space
        // The skybox horizon is where rayDir.z = 0 (horizontal ray from camera)
        // This is a point at infinity in a horizontal direction from the camera
        // We need to find where this projects to in clip space
        
        // Get a horizontal direction (camera forward projected onto XY plane)
        const horizonDir = vec3.fromValues(camera.forward[0], camera.forward[1], 0);
        if (vec3.length(horizonDir) > 0.001) {
            vec3.normalize(horizonDir, horizonDir);
        } else {
            vec3.set(horizonDir, 1, 0, 0);
        }
        
        // Transform a direction vector (not a point) to clip space
        // For a point at infinity in direction D, its clip space position is:
        // lim(t->inf) ViewProj * (eye + t*D) / w
        // Which equals ViewProj * D (as a vec4 with w=0), then we look at x/w, y/w
        // But since w would be 0 for a direction, we use the view matrix only
        
        // The horizon is where view-space Y = 0 for an infinite point
        // In our Z-up system, the horizon is where the ray is horizontal (z=0 in world)
        // Transform a horizontal direction through view matrix
        const horizonDirView = vec4.fromValues(horizonDir[0], horizonDir[1], 0, 0);
        vec4.transformMat4(horizonDirView, horizonDirView, view);
        
        // The Y in clip space where this direction points is based on the view-space direction
        // projected through the projection matrix
        // For perspective: clipY/clipW = viewY/(-viewZ) * projectionScaleY
        // For a horizontal ray at infinity, we can compute where it ends up
        
        // Simpler approach: transform a point very far away in horizon direction
        const farDist = 1000000.0;
        const horizonPoint = vec4.fromValues(
            camera.pos[0] + horizonDir[0] * farDist,
            camera.pos[1] + horizonDir[1] * farDist,
            camera.pos[2], // Same height as camera - this is the horizon!
            1
        );
        const viewProj = mat4.create();
        mat4.multiply(viewProj, projection, view);
        vec4.transformMat4(horizonPoint, horizonPoint, viewProj);
        const horizonClipY = horizonPoint[3] !== 0 ? horizonPoint[1] / horizonPoint[3] : 0;
        
        let uHorizonClipY_loc = gl.getUniformLocation(<WebGLProgram>defaultProgram, "uHorizonClipY");
        gl.uniform1f(uHorizonClipY_loc, horizonClipY);
        
        // Enable backface culling so ocean isn't visible from below
        gl.enable(gl.CULL_FACE);
        gl.cullFace(gl.BACK);
        gl.frontFace(gl.CCW);
        
        projectedOcean.draw(gl, wireframeMode);
        
        gl.disable(gl.CULL_FACE);
    }
    requestAnimationFrame(drawScene);
}

/** Handle FPS camera movement */
function handleCameraMovement() {
    const speed = keysPressed.has('Shift') ? fastMoveSpeed : moveSpeed;
    
    // WASD for horizontal movement
    if (keysPressed.has('w') || keysPressed.has('W')) {
        camera.moveForward(speed);
    }
    if (keysPressed.has('s') || keysPressed.has('S')) {
        camera.moveForward(-speed);
    }
    if (keysPressed.has('a') || keysPressed.has('A')) {
        camera.moveRight(-speed);
    }
    if (keysPressed.has('d') || keysPressed.has('D')) {
        camera.moveRight(speed);
    }
    
    // Q/E for vertical movement
    if (keysPressed.has('q') || keysPressed.has('Q')) {
        camera.moveUp(-speed);
    }
    if (keysPressed.has('e') || keysPressed.has('E')) {
        camera.moveUp(speed);
    }
    
    // Space to go up, Ctrl to go down
    if (keysPressed.has(' ')) {
        camera.moveUp(speed);
    }
    if (keysPressed.has('Control')) {
        camera.moveUp(-speed);
    }
}

function main() {
    const canvas: HTMLCanvasElement = <HTMLCanvasElement>document.getElementById("window");
    fpsDisplay = document.getElementById("fps-counter");
    
    const updateCanvasSize = initGL(canvas);
    if (!updateCanvasSize) {
        console.error("Failed to initialize WebGL");
        return;
    }

    var drag = false;
    var previousPosX: number | null;
    var previousPosY: number | null;
    canvas.addEventListener('mousedown', function (evt) {
        drag = true;
    }, false);
    canvas.addEventListener('mousemove', function (evt) {
        if (drag) {
            if (previousPosX == null || previousPosY == null) {
                previousPosX = evt.x;
                previousPosY = evt.y;
            }
            var mousePosX = evt.x;
            var mousePosY = evt.y;
            mouseXVel = (mousePosX - previousPosX);
            mouseYVel = (mousePosY - previousPosY);
            previousPosX = mousePosX;
            previousPosY = mousePosY;
        }
    }, false);
    var deactivateMouseMovement = function () {
        previousPosX = null;
        previousPosY = null;
        mouseXVel = 0.0;
        mouseYVel = 0.0;
        drag = false;
    }
    canvas.addEventListener('mouseup', deactivateMouseMovement, false);
    canvas.addEventListener('mouseleave', deactivateMouseMovement, false);

    // Keyboard controls
    window.addEventListener('keydown', (evt) => {
        keysPressed.add(evt.key);
        
        // Reset camera on 'R' key
        if (evt.key === 'r' || evt.key === 'R') {
            camera = new Camera(); // Reset to initial position
        }
        
        // Prevent default for space to avoid page scroll
        if (evt.key === ' ') {
            evt.preventDefault();
        }
    });
    
    window.addEventListener('keyup', (evt) => {
        keysPressed.delete(evt.key);
    });

    // Window resize handler
    window.addEventListener('resize', () => {
        updateCanvasSize(canvas);
    });
    
    // Wireframe toggle handler
    window.addEventListener('toggleWireframe', () => {
        wireframeMode = !wireframeMode;
        const wireframeBtn = document.getElementById('wireframe-toggle');
        if (wireframeBtn) {
            wireframeBtn.textContent = `Wireframe: ${wireframeMode ? 'ON' : 'OFF'}`;
        }
        console.log(`Wireframe mode: ${wireframeMode ? 'ON' : 'OFF'}`);
    });
    
    // Ocean settings sliders
    window.addEventListener('waveHeightChange', ((evt: CustomEvent) => {
        waveHeight = evt.detail;
    }) as EventListener);
    
    window.addEventListener('waveSpeedChange', ((evt: CustomEvent) => {
        waveSpeed = evt.detail;
    }) as EventListener);
    
    window.addEventListener('foamIntensityChange', ((evt: CustomEvent) => {
        foamIntensity = evt.detail;
    }) as EventListener);
    
    window.addEventListener('glitterIntensityChange', ((evt: CustomEvent) => {
        glitterIntensity = evt.detail;
    }) as EventListener);

    initShaders();
    initGeometry();
    initFBO();
    
    projectedOcean = new ProjectedOcean();
    projectedOcean.initVAO(gl);
    console.log(`Projected ocean initialized with ${projectedOcean.getIndexCount()} indices`);
    
    skybox = new Skybox();
    skybox.initVAO(gl);
    console.log('Skybox initialized');

    camera = new Camera();
    //Check if any errors apeared during init.
    if (gl.getError() != gl.NO_ERROR) {
        console.log("OpenGL Error!: ");
    }

    drawScene();
}

main();