#  Copyright (c) 2020. Author: Hanchen Wang, hc.wang96@gmail.com

#  Author: Wentao Yuan (wyuan1@cs.cmu.edu) 05/31/2018

import tensorflow as tf
from utils.tf_util import mlp_conv, point_maxpool, point_unpool, mlp, add_train_summary, \
    add_valid_summary, earth_mover, chamfer


class Model:
    def __init__(self, inputs, npts, gt, alpha, **kwargs):
        self.num_coarse = 1024
        self.grid_size = 4
        self.grid_scale = 0.05
        self.num_fine = self.grid_size ** 2 * self.num_coarse
        self.features = self.create_encoder(inputs, npts)
        self.coarse, self.fine = self.create_decoder(self.features)
        self.loss, self.update = self.create_loss(self.coarse, self.fine, gt, alpha)
        self.outputs = self.fine
        self.visualize_ops = [tf.split(inputs[0], npts, axis=0), self.coarse, self.fine, gt]
        self.visualize_titles = ['input', 'coarse output', 'fine output', 'ground truth']

    def create_encoder(self, inputs, npts):
        with tf.variable_scope('encoder_0', reuse=tf.AUTO_REUSE):
            features = mlp_conv(inputs, [128, 256])
            features_global = point_unpool(point_maxpool(features, npts, keepdims=True), npts)
            features = tf.concat([features, features_global], axis=2)
        with tf.variable_scope('encoder_1', reuse=tf.AUTO_REUSE):
            features = mlp_conv(features, [512, 1024])
            features = point_maxpool(features, npts)
        return features

    def create_decoder(self, features):
        with tf.variable_scope('decoder', reuse=tf.AUTO_REUSE):
            coarse = mlp(features, [1024, 1024, self.num_coarse * 3])
            coarse = tf.reshape(coarse, [-1, self.num_coarse, 3])

        with tf.variable_scope('folding', reuse=tf.AUTO_REUSE):
            x = tf.linspace(-self.grid_scale, self.grid_scale, self.grid_size)
            y = tf.linspace(-self.grid_scale, self.grid_scale, self.grid_size)
            grid = tf.meshgrid(x, y)
            grid = tf.expand_dims(tf.reshape(tf.stack(grid, axis=2), [-1, 2]), 0)
            grid_feat = tf.tile(grid, [features.shape[0], self.num_coarse, 1])

            point_feat = tf.tile(tf.expand_dims(coarse, 2), [1, 1, self.grid_size ** 2, 1])
            point_feat = tf.reshape(point_feat, [-1, self.num_fine, 3])

            global_feat = tf.tile(tf.expand_dims(features, 1), [1, self.num_fine, 1])

            feat = tf.concat([grid_feat, point_feat, global_feat], axis=2)

            center = tf.tile(tf.expand_dims(coarse, 2), [1, 1, self.grid_size ** 2, 1])
            center = tf.reshape(center, [-1, self.num_fine, 3])

            fine = mlp_conv(feat, [512, 512, 3]) + center
        return coarse, fine

    def create_loss(self, coarse, fine, gt, alpha):
        
        gt_ds = gt[:, :coarse.shape[1], :]
        
        loss_coarse = earth_mover(coarse, gt_ds)
        add_train_summary('train/coarse_loss', loss_coarse)
        update_coarse = add_valid_summary('valid/coarse_loss', loss_coarse)

        loss_fine = chamfer(fine, gt)
        add_train_summary('train/fine_loss', loss_fine)
        update_fine = add_valid_summary('valid/fine_loss', loss_fine)

        loss = loss_coarse + alpha * loss_fine
        add_train_summary('train/loss', loss)
        update_loss = add_valid_summary('valid/loss', loss)

        return loss, [update_coarse, update_fine, update_loss]
