/*
 * Copyright 2009, Google Inc.
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 *
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 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
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 * in the documentation and/or other materials provided with the
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 * contributors may be used to endorse or promote products derived from
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/**
 * @fileoverview This file contains functions for implementing picking.
 * It puts them in the "picking" module on the o3djs object.
 *
 *
 * This example shows one way to implement picking. Because O3D is shader
 * agnostic we can't handle picking automatically since we have no way of
 * knowing what the developer is going to do with their shaders. On the other
 * hand, we can provide various functions that make it possible to do your own
 * picking. Only you know which objects are pickable and which are not. For
 * example if you are making an RTS game, only you would know that units are
 * pickable but ground and explosions are not and that neither is your HUD.
 * Similarly, only you would know how your shaders manipulate the vertices
 * passed to them.
 *
 * It's possible that someone, maybe us, will create an engine to use o3d
 * that given a bunch of restrictions and flags on the data it accepts can
 * do picking in a more automatic way but that is not the goal of the o3d
 * api. Its goal is to provide a LOW-LEVEL shader agnostic API.
 */

o3djs.provide('o3djs.picking');

o3djs.require('o3djs.math');
o3djs.require('o3djs.dump');

/**
 * A Module for picking.
 * @namespace
 */
o3djs.picking = o3djs.picking || {};

/**
 * A ray.
 * @type {{near: !o3djs.math.Vector3, far: !o3djs.math.Vector3}}
 */
o3djs.picking.Ray = goog.typedef;

/**
 * Creates a new PickInfo.
 * @param {!o3d.Element} element The Element that was picked.
 * @param {!o3djs.picking.ShapeInfo} shapeInfo The ShapeInfo that was picked.
 * @param {!o3d.RayIntersectionInfo} rayIntersectionInfo Information about the
 *     pick.
 * @param {!o3djs.math.Vector3} worldIntersectionPosition world position of
 *     intersection.
 * @return {!o3djs.picking.PickInfo} The new PickInfo.
 */
o3djs.picking.createPickInfo = function(element,
                                        shapeInfo,
                                        rayIntersectionInfo,
                                        worldIntersectionPosition) {
  return new o3djs.picking.PickInfo(element,
                                    shapeInfo,
                                    rayIntersectionInfo,
                                    worldIntersectionPosition);
};

/**
 * Convert a pixel position relative to the top left corner of the client area
 * into the corresponding ray through the frustum in world space.
 * @param {number} clientXPosition x position relative to client area.
 * @param {number} clientYPosition y position relative to client area.
 * @param {!o3djs.math.Matrix4} view View matrix to transform with.
 * @param {!o3djs.math.Matrix4} projection Projection matrix to transform
 *     with.
 * @param {number} clientWidth width of client area.
 * @param {number} clientHeight height of client area.
 * @return {!o3djs.picking.Ray} ray in world space.
 */
o3djs.picking.clientPositionToWorldRayEx = function(clientXPosition,
                                                    clientYPosition,
                                                    view,
                                                    projection,
                                                    clientWidth,
                                                    clientHeight) {
  // compute the world position of a ray going through the view frustum
  var inverseViewProjectionMatrix = o3djs.math.inverse(
      o3djs.math.matrix4.composition(projection, view));
  // normScreenX, normScreenY are in frustum coordinates.
  var normScreenX = clientXPosition / (clientWidth * 0.5) - 1;
  var normScreenY = -(clientYPosition / (clientHeight * 0.5) - 1);

  // Apply inverse view-projection matrix to get the ray in world coordinates.
  return {
      near: o3djs.math.matrix4.transformPoint(
          inverseViewProjectionMatrix, [normScreenX, normScreenY, 0]),
      far: o3djs.math.matrix4.transformPoint(
          inverseViewProjectionMatrix, [normScreenX, normScreenY, 1])
  };
};

/**
 * Convert a pixel position relative to the top left corner of the client area
 * into the corresponding ray through the frustum in world space.
 * @param {number} clientXPosition x position relative to client area.
 * @param {number} clientYPosition y position relative to client area.
 * @param {!o3d.DrawContext} drawContext DrawContext to get view and
 *     projection matrices from.
 * @param {number} clientWidth width of client area.
 * @param {number} clientHeight height of client area.
 * @return {!o3djs.picking.Ray} ray in world space.
 */
o3djs.picking.clientPositionToWorldRay = function(clientXPosition,
                                                  clientYPosition,
                                                  drawContext,
                                                  clientWidth,
                                                  clientHeight) {
  return o3djs.picking.clientPositionToWorldRayEx(
      clientXPosition,
      clientYPosition,
      drawContext.view,
      drawContext.projection,
      clientWidth,
      clientHeight);
};

/**
 * A local dump function so we can easily comment it out.
 * @param {string} msg Message to dump.
 */
o3djs.picking.dprint = function(msg) {
  //o3djs.dump.dump(msg);
};

/**
 * A local dump function so we can easily comment it out.
 * @param {string} label Label to print before value.
 * @param {!o3djs.math.Vector3} float3 Value to print.
 * @param {string} prefix optional prefix for indenting.
 */
o3djs.picking.dprintPoint3 = function(label, float3, prefix) {
  //o3djs.dump.dumpPoint3(label, float3, prefix);
};

/**
 * A local dump function so we can easily comment it out.
 * @param {string} label Label to put in front of dump.
 * @param {!o3d.BoundingBox} boundingBox BoundingBox to dump.
 * @param {string} opt_prefix optional prefix for indenting.
 */
o3djs.picking.dprintBoundingBox = function(label,
                                           boundingBox,
                                           opt_prefix) {
  //o3djs.dump.dumpBoundingBox(label, boundingBox, opt_prefix);
};

/**
 * A local dump function so we can easily comment it out.
 * @param {string} label Label to print before value.
 * @param {!o3d.RayIntersectionInfo} rayIntersectionInfo Value to print.
 */
o3djs.picking.dumpRayIntersectionInfo = function(label,
                                                 rayIntersectionInfo) {
  o3djs.picking.dprint(
      label + ' : valid = ' +
      rayIntersectionInfo.valid + ' : intersected = ' +
      rayIntersectionInfo.intersected);
  if (rayIntersectionInfo.intersected) {
    o3djs.picking.dprint(
        ' : pos: ' +
        rayIntersectionInfo.position[0] + ', ' +
        rayIntersectionInfo.position[1] + ', ' +
        rayIntersectionInfo.position[2] + ', ');
  }
  o3djs.picking.dprint('\n');
};

/**
 * Creates a new PickInfo. Used to return picking information.
 * @constructor
 * @param {!o3d.Element} element The Element that was picked.
 * @param {!o3djs.picking.ShapeInfo} shapeInfo The ShapeInfo that was picked.
 * @param {!o3d.RayIntersectionInfo} rayIntersectionInfo Information about the
 *     pick.
 * @param {!o3djs.math.Vector3} worldIntersectionPosition world position of
 *     intersection.
 */
o3djs.picking.PickInfo = function(element,
                                  shapeInfo,
                                  rayIntersectionInfo,
                                  worldIntersectionPosition) {
  /**
   * The Element that was picked (Primitive).
   * @type {!o3d.Element}
   */
  this.element = element;

  /**
   * The ShapeInfo that was picked.
   * @type {!o3djs.picking.ShapeInfo}
   */
  this.shapeInfo = shapeInfo;

  /**
   * Information about the pick.
   * @type {!o3d.RayIntersectionInfo}
   */
  this.rayIntersectionInfo = rayIntersectionInfo;

  /**
   * The worldIntersectionPosition world position of intersection.
   * @type {!o3djs.math.Vector3}
   */
  this.worldIntersectionPosition = worldIntersectionPosition
};

/**
 * Creates a new ShapeInfo. Used to store information about Shapes. Note, even
 * though Shapes can be instanced, ShapeInfos can not so if a Shape is instanced
 * there will be more than one ShapeInfo for it.
 * @constructor
 * @param {!o3d.Shape} shape Shape to keep info about.
 * @param {!o3djs.picking.TransformInfo} parent Parent transform of the shape.
 * @param {!o3djs.picking.PickManager} pickManager The PickManager this
 *     ShapeInfo belongs to.
 */
o3djs.picking.ShapeInfo = function(shape, parent, pickManager) {
  /**
   * The Shape for this ShapeInfo
   * @type {!o3d.Shape}
   */
  this.shape = shape;

  /**
   * The parent TransformInfo of this Shape.
   * @type {!o3djs.picking.TransformInfo}
   */
  this.parent = parent;

  /**
   * The bounding box for this Shape
   * @type {o3d.BoundingBox}
   */
  this.boundingBox = null;

  /**
   * The PickManager this ShapeInfo belongs to.
   * @type {!o3djs.picking.PickManager}
   */
  this.pickManager = pickManager;

  this.update();
};

/**
 * Returns whether or not this ShapeInfo is pickable.
 * @return {boolean} Whether or not this ShapeInfo is pickable.
 */
o3djs.picking.ShapeInfo.prototype.isPickable = function() {
  return true;
}

/**
 * Gets the BoundingBox of the Shape in this ShapeInfo.
 * @return {o3d.BoundingBox} The Shape's BoundingBox.
 */
o3djs.picking.ShapeInfo.prototype.getBoundingBox = function() {
  return this.boundingBox;
};

/**
 * Updates the BoundingBox of the Shape in this ShapeInfo.
 */
o3djs.picking.ShapeInfo.prototype.update = function() {
  var elements = this.shape.elements;
  if (elements.length > 0) {
    this.boundingBox = elements[0].getBoundingBox(0);
    for (var ee = 1; ee < elements.length; ee++) {
      this.boundingBox = this.boundingBox.add(elements[ee].getBoundingBox(0));
    }
  }
};

/**
 * Attempts to "pick" this Shape by checking for the intersection of a ray
 * in world space to the triangles this shape uses.
 * @param {!o3djs.picking.Ray} worldRay A ray in world space to pick against.
 * @return {o3djs.picking.PickInfo} Information about the picking.
 *     null if the ray did not intersect any triangles.
 */
o3djs.picking.ShapeInfo.prototype.pick = function(worldRay) {
  if (this.isPickable()) {
    var worldMatrix = this.parent.transform.getUpdatedWorldMatrix()
    var inverseWorldMatrix = o3djs.math.inverse(worldMatrix);
    var relativeNear = o3djs.math.matrix4.transformPoint(
        inverseWorldMatrix, worldRay.near);
    var relativeFar = o3djs.math.matrix4.transformPoint(
        inverseWorldMatrix, worldRay.far);
    var rayIntersectionInfo =
        this.boundingBox.intersectRay(relativeNear,
                                      relativeFar);

    o3djs.picking.dumpRayIntersectionInfo('SHAPE(box): ' + this.shape.name,
                                          rayIntersectionInfo);

    if (rayIntersectionInfo.intersected) {
      var elements = this.shape.elements;
      for (var e = 0; e < elements.length; e++) {
        var element = elements[e];
        rayIntersectionInfo = element.intersectRay(
            0,
            o3djs.base.o3d.State.CULL_CCW,
            relativeNear,
            relativeFar);
        o3djs.picking.dumpRayIntersectionInfo(
            'SHAPE(tris): ' + this.shape.name + ' : element ' + element.name,
            rayIntersectionInfo);

        // TODO: get closest element not just first element.
        if (rayIntersectionInfo.intersected) {
          var worldIntersectionPosition = o3djs.math.matrix4.transformPoint(
              worldMatrix, rayIntersectionInfo.position);
          return o3djs.picking.createPickInfo(element,
                                              this,
                                              rayIntersectionInfo,
                                              worldIntersectionPosition);
        }
      }
    }
  }
  return null;
};

/**
 * Dumps info about a ShapeInfo
 * @param {string} opt_prefix optional prefix for indenting.
 */
o3djs.picking.ShapeInfo.prototype.dump = function(opt_prefix) {
  var prefix = opt_prefix || '';
  o3djs.picking.dprint(prefix + 'SHAPE: ' + this.shape.name + '\n');
  o3djs.picking.dprintPoint3('bb min',
                             this.boundingBox.minExtent,
                             prefix + '    ');
  o3djs.picking.dprintPoint3('bb max',
                             this.boundingBox.maxExtent,
                             prefix + '    ');
};

/**
 * Creates a new TransformInfo. Used to store information about Transforms.
 * @constructor
 * @param {!o3d.Transform} transform Transform to keep info about.
 * @param {o3djs.picking.TransformInfo} parent Parent transformInfo of the
 *     transform. Can be null.
 * @param {!o3djs.picking.PickManager} pickManager The PickManager this
 *     ShapeInfo belongs to.
 */
o3djs.picking.TransformInfo = function(transform, parent, pickManager) {
  /**
   * TransformInfos for children by client id.
   * @type {!Object.<number, !o3djs.picking.TransformInfo>}
   */
  this.childTransformInfos = {};

  /**
   * ShapeInfos for shape of this transform by client id.
   * @type {!Object.<number, !o3djs.picking.ShapeInfo>}
   */
  this.shapeInfos = {};

  /**
   * The transform of this transform info.
   * @type {!o3d.Transform}
   */
  this.transform = transform;

  /**
   * The parent of this transform info.
   * @type {o3djs.picking.TransformInfo}
   */
  this.parent = parent;

  /**
   * The bounding box of this transform info.
   * @type {o3d.BoundingBox}
   */
  this.boundingBox = null;

  /**
   * The PickManager this TransformInfo belongs to.
   * @type {!o3djs.picking.PickManager}
   */
  this.pickManager = pickManager;

  /**
   * Whether or not this object is pickable when invisible.
   * This is useful for collision geometry that is not visible.
   * Of course it might argubly be better to store collision geometry
   * in a separate graph from visible geometry but sometimes it's useful
   * to have them in the same graph.
   * @type {boolean}
   */
  this.pickableEvenIfInvisible = false;
};

/**
 * Gets the BoundingBox of the Transform in this TransformInfo.
 * @return {o3d.BoundingBox} The Transform's BoundingBox.
 */
o3djs.picking.TransformInfo.prototype.getBoundingBox = function() {
  return this.boundingBox;
};

/**
 * Returns whether or not this TransformInfo is pickable.
 *
 * If this TransformInfo is not pickable then all child shapes and
 * TransformInfos will be skipped during the picking process.
 *
 * @return {boolean} Whether or not this TransformInfo is pickable.
 */
o3djs.picking.TransformInfo.prototype.isPickable = function() {
  return this.transform.visible || this.pickableEvenIfInvisible;
};

/**
 * Updates the shape and child lists for this TransformInfo and recomputes its
 * BoundingBox.
 */
o3djs.picking.TransformInfo.prototype.update = function() {
  var newChildTransformInfos = {};
  var newShapeInfos = {};
  // We need to add new children and remove old ones so we walk the children
  // and for each one we find, if it already has a TransformInfo or ShapeInfo we
  // add it to our new lists, if not we create one and add it to our new lists.
  var children = this.transform.children;
  for (var c = 0; c < children.length; c++) {
    var child = children[c];
    var transformInfo = this.childTransformInfos[child.clientId];
    if (!transformInfo) {
      transformInfo = this.pickManager.createTransformInfo(child, this);
    } else {
      // clear the boundingBox so we'll regenerate it.
      transformInfo.boundingBox = null;
    }
    transformInfo.update();
    newChildTransformInfos[child.clientId] = transformInfo;
  }
  var shapes = this.transform.shapes;
  for (var s = 0; s < shapes.length; s++) {
    var shape = shapes[s];
    var shapeInfo = this.shapeInfos[shape.clientId];
    if (!shapeInfo) {
      shapeInfo = this.pickManager.createShapeInfo(shape, this);
    } else {
      // unless the vertices or elements change there is no need to
      // recompute this.
      // shapeInfo.update();
    }
    newShapeInfos[shape.clientId] = shapeInfo;
  }

  // o3djs.picking.dprint(
  //   'num Children: ' + children.length + '\n');
  // o3djs.picking.dprint(
  //   'num Shapes: ' + shapes.length + '\n');

  // Now our new lists have the correct children so replace the old lists.
  // and remove any old children from the PickManager.
  for (var skey in this.childTransformInfos) {
    var key = /** @type {number} */ (skey);
    if (!newChildTransformInfos[key]) {
      this.pickManager.removeTransformInfo(this.childTransformInfos[key]);
    }
  }

  this.childTransformInfos = newChildTransformInfos;
  this.shapeInfos = newShapeInfos;

  var boundingBox = null;
  for (var key in newShapeInfos) {
    var shapeInfo = newShapeInfos[key];
    if (shapeInfo.isPickable()) {
      var box = shapeInfo.getBoundingBox().mul(this.transform.localMatrix);
      if (!boundingBox) {
        boundingBox = box;
      } else if (box) {
        boundingBox = boundingBox.add(box);
      }
    }
  }

  for (var key in newChildTransformInfos) {
    var transformInfo = newChildTransformInfos[key];
    if (transformInfo.isPickable()) {
      // Note: If there is no shape at the leaf on this branch
      // there will be no bounding box.
      var box = transformInfo.getBoundingBox();
      if (box) {
        if (!boundingBox) {
          boundingBox = box.mul(this.transform.localMatrix);
        } else {
          boundingBox = boundingBox.add(box.mul(this.transform.localMatrix));
        }
      }
    }
  }

  this.boundingBox = boundingBox;
};

/**
 * Attempts to "pick" this TransformInfo by checking for the intersection of a
 * ray in world space to the boundingbox of the TransformInfo. If intesection
 * is succesful recursively calls its children and shapes to try to find
 * a single Shape that is hit by the ray.
 * @param {!o3djs.picking.Ray} worldRay A ray in world space to pick against.
 * @return {o3djs.picking.PickInfo} Information about the picking.
 *     null if the ray did not intersect any triangles.
 */
o3djs.picking.TransformInfo.prototype.pick = function(worldRay) {
  if (this.isPickable() && this.boundingBox) {
    var inverseWorldMatrix = o3djs.math.matrix4.identity();
    if (this.parent) {
      inverseWorldMatrix = o3djs.math.inverse(
          this.parent.transform.getUpdatedWorldMatrix());
    }
    var relativeNear =
        o3djs.math.matrix4.transformPoint(inverseWorldMatrix, worldRay.near);
    var relativeFar =
        o3djs.math.matrix4.transformPoint(inverseWorldMatrix, worldRay.far);
    var rayIntersectionInfo =
        this.boundingBox.intersectRay(relativeNear, relativeFar);
    o3djs.picking.dumpRayIntersectionInfo(
        'TRANSFORM(box): ' + this.transform.name, rayIntersectionInfo);

    if (rayIntersectionInfo.intersected) {
      var closestPickInfo = null;
      var minDistance = -1;
      for (var skey in this.childTransformInfos) {
        var key = /** @type {number} */ (skey);
        var transformInfo = this.childTransformInfos[key];
        var pickInfo = transformInfo.pick(worldRay);
        if (pickInfo) {
          // is this closer than the last one?
          var distance = o3djs.math.lengthSquared(
              o3djs.math.subVector(worldRay.near,
                                   pickInfo.worldIntersectionPosition));
          if (!closestPickInfo || distance < minDistance) {
            minDistance = distance;
            closestPickInfo = pickInfo;
          }
        }
      }

      for (var skey in this.shapeInfos) {
        var key = /** @type {number} */ (skey);
        var shapeInfo = this.shapeInfos[key];
        var pickInfo = shapeInfo.pick(worldRay);
        if (pickInfo) {
          // is this closer than the last one?
          var distance = o3djs.math.lengthSquared(
              o3djs.math.subVector(worldRay.near,
                                   pickInfo.worldIntersectionPosition));
          if (!closestPickInfo || distance < minDistance) {
            minDistance = distance;
            closestPickInfo = pickInfo;
          }
        }
      }
      return closestPickInfo;
    }
  }
  return null;
};

/**
 * Dumps info about a TransformInfo
 * @param {string} opt_prefix optional prefix for indenting.
 */
o3djs.picking.TransformInfo.prototype.dump = function(opt_prefix) {
  var prefix = opt_prefix || '';

  o3djs.picking.dprint(prefix + 'TRANSFORM: ' + this.transform.name +
                       '\n');

  if (this.boundingBox) {
    o3djs.picking.dprintPoint3('bb min',
                               this.boundingBox.minExtent,
                               prefix + '    ');
    o3djs.picking.dprintPoint3('bb max',
                               this.boundingBox.maxExtent,
                               prefix + '    ');
  } else {
    o3djs.picking.dprint(prefix + '    bb *NA*\n');
  }

  o3djs.picking.dprint(prefix + '--Shapes--\n');
  for (var skey in this.shapeInfos) {
    var key = /** @type {number} */ (skey);
    var shapeInfo = this.shapeInfos[key];
    shapeInfo.dump(prefix + '    ');
  }

  o3djs.picking.dprint(prefix + '--Children--\n');
  for (var skey in this.childTransformInfos) {
    var key = /** @type {number} */ (skey);
    var transformInfo = this.childTransformInfos[key];
    transformInfo.dump(prefix + '    ');
  }
};

/**
 * A PickManager manages picking of primitives from a transform graph.
 * @constructor
 * @param {!o3d.Transform} rootTransform The root of the transform graph this
 *     PickManager should manage.
 */
o3djs.picking.PickManager = function(rootTransform) {
  /**
   * TransformInfos for transforms of this PickManager by client id.
   * @type {!Object.<number, !o3djs.picking.TransformInfo>}
   */
  this.transformInfosByClientId = {};

  /**
   * The root transform for this PickManager.
   * @type {!o3djs.picking.TransformInfo}
   */
  this.rootTransformInfo = this.createTransformInfo(rootTransform, null);
};

/**
 * Creates a new ShapeInfo.
 * @param {!o3d.Shape} shape Shape to keep info about.
 * @param {!o3djs.picking.TransformInfo} parent Parent transform of the shape.
 * @return {!o3djs.picking.ShapeInfo} The new ShapeInfo.
 */
o3djs.picking.PickManager.prototype.createShapeInfo = function(shape, parent) {
  return new o3djs.picking.ShapeInfo(shape, parent, this);
};

/**
 * Creates a new TransformInfo.
 * @param {!o3d.Transform} transform Transform to keep info about.
 * @param {o3djs.picking.TransformInfo} parent Parent transform of the
 *     transform. Can be null.
 * @return {!o3djs.picking.TransformInfo} The new TransformInfo.
 */
o3djs.picking.PickManager.prototype.createTransformInfo =
    function(transform, parent) {
  var info = new o3djs.picking.TransformInfo(transform, parent, this);
  this.addTransformInfo(info);
  return info;
};

/**
 * Adds a transform info to this PickManager.
 * @param {!o3djs.picking.TransformInfo} transformInfo The TransformInfo to add.
 */
o3djs.picking.PickManager.prototype.addTransformInfo = function(transformInfo) {
  this.transformInfosByClientId[transformInfo.transform.clientId] =
      transformInfo;
};

/**
 * Removes a transform info from this PickManager.
 * @param {!o3djs.picking.TransformInfo} transformInfo The TransformInfo to
 *     remove.
 */
o3djs.picking.PickManager.prototype.removeTransformInfo =
    function(transformInfo) {
  delete this.transformInfosByClientId[transformInfo.transform.clientId];
};

/**
 * Gets a transform info from this PickManager by transform.
 * @param {!o3d.Transform} transform The Transform to get a TransformInfo for.
 * @return {o3djs.picking.TransformInfo} The TransformInfo for the transform or
 *      null if there isn't one.
 */
o3djs.picking.PickManager.prototype.getTransformInfo = function(transform) {
  return this.transformInfosByClientId[transform.clientId];
};

/**
 * Updates the picking info to match the transform graph in its current state.
 */
o3djs.picking.PickManager.prototype.update = function() {
  this.rootTransformInfo.update();
};

/**
 * Dumps info about a PickManager
 */
o3djs.picking.PickManager.prototype.dump = function() {
  this.rootTransformInfo.dump();
};

/**
 * Attempts to "pick" objects managed by this PickManager.
 * @param {!o3djs.picking.Ray} worldRay A ray in world space to pick against.
 * @return {o3djs.picking.PickInfo} Information about the picking.
 *     null if the ray did not intersect any triangles.
 */
o3djs.picking.PickManager.prototype.pick = function(worldRay) {
  return this.rootTransformInfo.pick(worldRay);
};

/**
 * Creates a PickManager.
 * @param {!o3d.Transform} rootTransform The root of the transform graph this
 *     PickManager should manage.
 * @return {!o3djs.picking.PickManager} The created PickManager.
 */
o3djs.picking.createPickManager = function(rootTransform) {
  return new o3djs.picking.PickManager(rootTransform);
};