/**
 * @module ol/render/webgl/TextureReplay
 */
import {getUid, inherits} from '../../index.js';
import {intersects} from '../../extent.js';
import {isEmpty} from '../../obj.js';
import {fragment, vertex} from '../webgl/texturereplay/defaultshader.js';
import Locations from '../webgl/texturereplay/defaultshader/Locations.js';
import WebGLReplay from '../webgl/Replay.js';
import {CLAMP_TO_EDGE, FLOAT, TEXTURE_2D} from '../../webgl.js';
import {createTexture} from '../../webgl/Context.js';

/**
 * @constructor
 * @abstract
 * @extends {ol.render.webgl.Replay}
 * @param {number} tolerance Tolerance.
 * @param {module:ol/extent~Extent} maxExtent Max extent.
 * @struct
 */
const WebGLTextureReplay = function(tolerance, maxExtent) {
  WebGLReplay.call(this, tolerance, maxExtent);

  /**
   * @type {number|undefined}
   * @protected
   */
  this.anchorX = undefined;

  /**
   * @type {number|undefined}
   * @protected
   */
  this.anchorY = undefined;

  /**
   * @type {Array.<number>}
   * @protected
   */
  this.groupIndices = [];

  /**
   * @type {Array.<number>}
   * @protected
   */
  this.hitDetectionGroupIndices = [];

  /**
   * @type {number|undefined}
   * @protected
   */
  this.height = undefined;

  /**
   * @type {number|undefined}
   * @protected
   */
  this.imageHeight = undefined;

  /**
   * @type {number|undefined}
   * @protected
   */
  this.imageWidth = undefined;

  /**
   * @protected
   * @type {ol.render.webgl.texturereplay.defaultshader.Locations}
   */
  this.defaultLocations = null;

  /**
   * @protected
   * @type {number|undefined}
   */
  this.opacity = undefined;

  /**
   * @type {number|undefined}
   * @protected
   */
  this.originX = undefined;

  /**
   * @type {number|undefined}
   * @protected
   */
  this.originY = undefined;

  /**
   * @protected
   * @type {boolean|undefined}
   */
  this.rotateWithView = undefined;

  /**
   * @protected
   * @type {number|undefined}
   */
  this.rotation = undefined;

  /**
   * @protected
   * @type {number|undefined}
   */
  this.scale = undefined;

  /**
   * @type {number|undefined}
   * @protected
   */
  this.width = undefined;
};

inherits(WebGLTextureReplay, WebGLReplay);


/**
 * @inheritDoc
 */
WebGLTextureReplay.prototype.getDeleteResourcesFunction = function(context) {
  const verticesBuffer = this.verticesBuffer;
  const indicesBuffer = this.indicesBuffer;
  const textures = this.getTextures(true);
  const gl = context.getGL();
  return function() {
    if (!gl.isContextLost()) {
      let i, ii;
      for (i = 0, ii = textures.length; i < ii; ++i) {
        gl.deleteTexture(textures[i]);
      }
    }
    context.deleteBuffer(verticesBuffer);
    context.deleteBuffer(indicesBuffer);
  };
};


/**
 * @param {Array.<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {number} end End.
 * @param {number} stride Stride.
 * @return {number} My end.
 * @protected
 */
WebGLTextureReplay.prototype.drawCoordinates = function(flatCoordinates, offset, end, stride) {
  const anchorX = /** @type {number} */ (this.anchorX);
  const anchorY = /** @type {number} */ (this.anchorY);
  const height = /** @type {number} */ (this.height);
  const imageHeight = /** @type {number} */ (this.imageHeight);
  const imageWidth = /** @type {number} */ (this.imageWidth);
  const opacity = /** @type {number} */ (this.opacity);
  const originX = /** @type {number} */ (this.originX);
  const originY = /** @type {number} */ (this.originY);
  const rotateWithView = this.rotateWithView ? 1.0 : 0.0;
  // this.rotation_ is anti-clockwise, but rotation is clockwise
  const rotation = /** @type {number} */ (-this.rotation);
  const scale = /** @type {number} */ (this.scale);
  const width = /** @type {number} */ (this.width);
  const cos = Math.cos(rotation);
  const sin = Math.sin(rotation);
  let numIndices = this.indices.length;
  let numVertices = this.vertices.length;
  let i, n, offsetX, offsetY, x, y;
  for (i = offset; i < end; i += stride) {
    x = flatCoordinates[i] - this.origin[0];
    y = flatCoordinates[i + 1] - this.origin[1];

    // There are 4 vertices per [x, y] point, one for each corner of the
    // rectangle we're going to draw. We'd use 1 vertex per [x, y] point if
    // WebGL supported Geometry Shaders (which can emit new vertices), but that
    // is not currently the case.
    //
    // And each vertex includes 8 values: the x and y coordinates, the x and
    // y offsets used to calculate the position of the corner, the u and
    // v texture coordinates for the corner, the opacity, and whether the
    // the image should be rotated with the view (rotateWithView).

    n = numVertices / 8;

    // bottom-left corner
    offsetX = -scale * anchorX;
    offsetY = -scale * (height - anchorY);
    this.vertices[numVertices++] = x;
    this.vertices[numVertices++] = y;
    this.vertices[numVertices++] = offsetX * cos - offsetY * sin;
    this.vertices[numVertices++] = offsetX * sin + offsetY * cos;
    this.vertices[numVertices++] = originX / imageWidth;
    this.vertices[numVertices++] = (originY + height) / imageHeight;
    this.vertices[numVertices++] = opacity;
    this.vertices[numVertices++] = rotateWithView;

    // bottom-right corner
    offsetX = scale * (width - anchorX);
    offsetY = -scale * (height - anchorY);
    this.vertices[numVertices++] = x;
    this.vertices[numVertices++] = y;
    this.vertices[numVertices++] = offsetX * cos - offsetY * sin;
    this.vertices[numVertices++] = offsetX * sin + offsetY * cos;
    this.vertices[numVertices++] = (originX + width) / imageWidth;
    this.vertices[numVertices++] = (originY + height) / imageHeight;
    this.vertices[numVertices++] = opacity;
    this.vertices[numVertices++] = rotateWithView;

    // top-right corner
    offsetX = scale * (width - anchorX);
    offsetY = scale * anchorY;
    this.vertices[numVertices++] = x;
    this.vertices[numVertices++] = y;
    this.vertices[numVertices++] = offsetX * cos - offsetY * sin;
    this.vertices[numVertices++] = offsetX * sin + offsetY * cos;
    this.vertices[numVertices++] = (originX + width) / imageWidth;
    this.vertices[numVertices++] = originY / imageHeight;
    this.vertices[numVertices++] = opacity;
    this.vertices[numVertices++] = rotateWithView;

    // top-left corner
    offsetX = -scale * anchorX;
    offsetY = scale * anchorY;
    this.vertices[numVertices++] = x;
    this.vertices[numVertices++] = y;
    this.vertices[numVertices++] = offsetX * cos - offsetY * sin;
    this.vertices[numVertices++] = offsetX * sin + offsetY * cos;
    this.vertices[numVertices++] = originX / imageWidth;
    this.vertices[numVertices++] = originY / imageHeight;
    this.vertices[numVertices++] = opacity;
    this.vertices[numVertices++] = rotateWithView;

    this.indices[numIndices++] = n;
    this.indices[numIndices++] = n + 1;
    this.indices[numIndices++] = n + 2;
    this.indices[numIndices++] = n;
    this.indices[numIndices++] = n + 2;
    this.indices[numIndices++] = n + 3;
  }

  return numVertices;
};


/**
 * @protected
 * @param {Array.<WebGLTexture>} textures Textures.
 * @param {Array.<HTMLCanvasElement|HTMLImageElement|HTMLVideoElement>} images Images.
 * @param {!Object.<string, WebGLTexture>} texturePerImage Texture cache.
 * @param {WebGLRenderingContext} gl Gl.
 */
WebGLTextureReplay.prototype.createTextures = function(textures, images, texturePerImage, gl) {
  let texture, image, uid, i;
  const ii = images.length;
  for (i = 0; i < ii; ++i) {
    image = images[i];

    uid = getUid(image).toString();
    if (uid in texturePerImage) {
      texture = texturePerImage[uid];
    } else {
      texture = createTexture(
        gl, image, CLAMP_TO_EDGE, CLAMP_TO_EDGE);
      texturePerImage[uid] = texture;
    }
    textures[i] = texture;
  }
};


/**
 * @inheritDoc
 */
WebGLTextureReplay.prototype.setUpProgram = function(gl, context, size, pixelRatio) {
  // get the program
  const program = context.getProgram(fragment, vertex);

  // get the locations
  let locations;
  if (!this.defaultLocations) {
    locations = new Locations(gl, program);
    this.defaultLocations = locations;
  } else {
    locations = this.defaultLocations;
  }

  // use the program (FIXME: use the return value)
  context.useProgram(program);

  // enable the vertex attrib arrays
  gl.enableVertexAttribArray(locations.a_position);
  gl.vertexAttribPointer(locations.a_position, 2, FLOAT,
    false, 32, 0);

  gl.enableVertexAttribArray(locations.a_offsets);
  gl.vertexAttribPointer(locations.a_offsets, 2, FLOAT,
    false, 32, 8);

  gl.enableVertexAttribArray(locations.a_texCoord);
  gl.vertexAttribPointer(locations.a_texCoord, 2, FLOAT,
    false, 32, 16);

  gl.enableVertexAttribArray(locations.a_opacity);
  gl.vertexAttribPointer(locations.a_opacity, 1, FLOAT,
    false, 32, 24);

  gl.enableVertexAttribArray(locations.a_rotateWithView);
  gl.vertexAttribPointer(locations.a_rotateWithView, 1, FLOAT,
    false, 32, 28);

  return locations;
};


/**
 * @inheritDoc
 */
WebGLTextureReplay.prototype.shutDownProgram = function(gl, locations) {
  gl.disableVertexAttribArray(locations.a_position);
  gl.disableVertexAttribArray(locations.a_offsets);
  gl.disableVertexAttribArray(locations.a_texCoord);
  gl.disableVertexAttribArray(locations.a_opacity);
  gl.disableVertexAttribArray(locations.a_rotateWithView);
};


/**
 * @inheritDoc
 */
WebGLTextureReplay.prototype.drawReplay = function(gl, context, skippedFeaturesHash, hitDetection) {
  const textures = hitDetection ? this.getHitDetectionTextures() : this.getTextures();
  const groupIndices = hitDetection ? this.hitDetectionGroupIndices : this.groupIndices;

  if (!isEmpty(skippedFeaturesHash)) {
    this.drawReplaySkipping(gl, context, skippedFeaturesHash, textures, groupIndices);
  } else {
    let i, ii, start;
    for (i = 0, ii = textures.length, start = 0; i < ii; ++i) {
      gl.bindTexture(TEXTURE_2D, textures[i]);
      const end = groupIndices[i];
      this.drawElements(gl, context, start, end);
      start = end;
    }
  }
};


/**
 * Draw the replay while paying attention to skipped features.
 *
 * This functions creates groups of features that can be drawn to together,
 * so that the number of `drawElements` calls is minimized.
 *
 * For example given the following texture groups:
 *
 *    Group 1: A B C
 *    Group 2: D [E] F G
 *
 * If feature E should be skipped, the following `drawElements` calls will be
 * made:
 *
 *    drawElements with feature A, B and C
 *    drawElements with feature D
 *    drawElements with feature F and G
 *
 * @protected
 * @param {WebGLRenderingContext} gl gl.
 * @param {module:ol/webgl/Context~WebGLContext} context Context.
 * @param {Object.<string, boolean>} skippedFeaturesHash Ids of features
 *  to skip.
 * @param {Array.<WebGLTexture>} textures Textures.
 * @param {Array.<number>} groupIndices Texture group indices.
 */
WebGLTextureReplay.prototype.drawReplaySkipping = function(gl, context, skippedFeaturesHash, textures,
  groupIndices) {
  let featureIndex = 0;

  let i, ii;
  for (i = 0, ii = textures.length; i < ii; ++i) {
    gl.bindTexture(TEXTURE_2D, textures[i]);
    const groupStart = (i > 0) ? groupIndices[i - 1] : 0;
    const groupEnd = groupIndices[i];

    let start = groupStart;
    let end = groupStart;
    while (featureIndex < this.startIndices.length &&
        this.startIndices[featureIndex] <= groupEnd) {
      const feature = this.startIndicesFeature[featureIndex];

      const featureUid = getUid(feature).toString();
      if (skippedFeaturesHash[featureUid] !== undefined) {
        // feature should be skipped
        if (start !== end) {
          // draw the features so far
          this.drawElements(gl, context, start, end);
        }
        // continue with the next feature
        start = (featureIndex === this.startIndices.length - 1) ?
          groupEnd : this.startIndices[featureIndex + 1];
        end = start;
      } else {
        // the feature is not skipped, augment the end index
        end = (featureIndex === this.startIndices.length - 1) ?
          groupEnd : this.startIndices[featureIndex + 1];
      }
      featureIndex++;
    }

    if (start !== end) {
      // draw the remaining features (in case there was no skipped feature
      // in this texture group, all features of a group are drawn together)
      this.drawElements(gl, context, start, end);
    }
  }
};


/**
 * @inheritDoc
 */
WebGLTextureReplay.prototype.drawHitDetectionReplayOneByOne = function(gl, context, skippedFeaturesHash,
  featureCallback, opt_hitExtent) {
  let i, groupStart, start, end, feature, featureUid;
  let featureIndex = this.startIndices.length - 1;
  const hitDetectionTextures = this.getHitDetectionTextures();
  for (i = hitDetectionTextures.length - 1; i >= 0; --i) {
    gl.bindTexture(TEXTURE_2D, hitDetectionTextures[i]);
    groupStart = (i > 0) ? this.hitDetectionGroupIndices[i - 1] : 0;
    end = this.hitDetectionGroupIndices[i];

    // draw all features for this texture group
    while (featureIndex >= 0 &&
        this.startIndices[featureIndex] >= groupStart) {
      start = this.startIndices[featureIndex];
      feature = this.startIndicesFeature[featureIndex];
      featureUid = getUid(feature).toString();

      if (skippedFeaturesHash[featureUid] === undefined &&
          feature.getGeometry() &&
          (opt_hitExtent === undefined || intersects(
            /** @type {Array<number>} */ (opt_hitExtent),
            feature.getGeometry().getExtent()))) {
        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
        this.drawElements(gl, context, start, end);

        const result = featureCallback(feature);
        if (result) {
          return result;
        }
      }

      end = start;
      featureIndex--;
    }
  }
  return undefined;
};


/**
 * @inheritDoc
 */
WebGLTextureReplay.prototype.finish = function(context) {
  this.anchorX = undefined;
  this.anchorY = undefined;
  this.height = undefined;
  this.imageHeight = undefined;
  this.imageWidth = undefined;
  this.indices = null;
  this.opacity = undefined;
  this.originX = undefined;
  this.originY = undefined;
  this.rotateWithView = undefined;
  this.rotation = undefined;
  this.scale = undefined;
  this.vertices = null;
  this.width = undefined;
};


/**
 * @abstract
 * @protected
 * @param {boolean=} opt_all Return hit detection textures with regular ones.
 * @returns {Array.<WebGLTexture>} Textures.
 */
WebGLTextureReplay.prototype.getTextures = function(opt_all) {};


/**
 * @abstract
 * @protected
 * @returns {Array.<WebGLTexture>} Textures.
 */
WebGLTextureReplay.prototype.getHitDetectionTextures = function() {};
export default WebGLTextureReplay;