#!/usr/bin/env python
# -*- coding: utf-8 -*-


'''
    #########################################
    ## SYNCHRONIZE CAMERAS                 ##
    #########################################

    
    TODO:
    - no ref cam (least amount of frames), no kpt selection
    - recap
    - whole sequence or around approx time (if long)
    - somehow fix demo (offset 0 frames when 0 frames offset, right now [0,-2,-2]) -> min_conf = 0.4 (check problem with 0.0)
    - switch to other person if jump in json_data, [0,0,0] if no person without jump



    Steps undergone in this script
    0. Converting json files to pandas dataframe
    1. Computing speeds (vertical)
    2. Plotting paired correlations of speeds from one camera viewpoint to another (work on one single keypoint, or on all keypoints, or on a weighted selection of keypoints)
    3. 
    Ideally, this should be done automatically for all views, checking pairs 2 by 2 with the highest correlation coefficient, 
    and ask for confirmation before deleting the frames in question (actually renamed .json.del - reset_sync option in Config.toml).
'''


## INIT
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from scipy import signal
from scipy import interpolate
import json
import os
import fnmatch
import pickle as pk
import re
from anytree import RenderTree
from anytree.importer import DictImporter
from Pose2Sim.skeletons import *


## AUTHORSHIP INFORMATION
__author__ = "David Pagnon, HunMin Kim"
__copyright__ = "Copyright 2021, Pose2Sim"
__credits__ = ["David Pagnon"]
__license__ = "BSD 3-Clause License"
__version__ = '0.7'
__maintainer__ = "David Pagnon"
__email__ = "contact@david-pagnon.com"
__status__ = "Development"


# FUNCTIONS
def sort_stringlist_by_last_number(string_list):
    '''
    Sort a list of strings based on the last number in the string.
    Works if other numbers in the string, if strings after number. Ignores alphabetical order.

    Example: ['json1', 'js4on2.b', 'eypoints_0000003.json', 'ajson0', 'json10']
    gives: ['ajson0', 'json1', 'js4on2.b', 'eypoints_0000003.json', 'json10']
    '''
    
    def sort_by_last_number(s):
        return int(re.findall(r'\d+', s)[-1])
    
    return sorted(string_list, key=sort_by_last_number)


def convert_json2pandas(json_dir, min_conf=0.6, frame_range=[]):
    '''
    Convert JSON files in a directory to a pandas DataFrame.

    INPUTS:
    - json_dir: str. The directory path containing the JSON files.
    - min_conf: float. Drop values if confidence is below min_conf.
    - frame_range: select files within frame_range.

    OUTPUT:
    - df_json_coords: dataframe. Extracted coordinates in a pandas dataframe.
    '''

    nb_coord = 25 # int(len(json_data)/3)
    json_files_names = fnmatch.filter(os.listdir(os.path.join(json_dir)), '*.json') # modified ( 'json' to '*.json' )
    json_files_names = sort_stringlist_by_last_number(json_files_names)
    if len(frame_range) == 2:
        json_files_names = np.array(json_files_names)[range(frame_range[0], frame_range[1])].tolist()
    json_files_path = [os.path.join(json_dir, j_f) for j_f in json_files_names]
    json_coords = []

    for j_p in json_files_path:
        with open(j_p) as j_f:
            try:
                json_data = json.load(j_f)['people'][0]['pose_keypoints_2d']
                # remove points with low confidence
                json_data = np.array([[json_data[3*i],json_data[3*i+1],json_data[3*i+2]] if json_data[3*i+2]>min_conf else [0.,0.,0.] for i in range(nb_coord)]).ravel().tolist()
            except:
                # print(f'No person found in {os.path.basename(json_dir)}, frame {i}')
                json_data = [np.nan] * 25*3
        json_coords.append(json_data)
    df_json_coords = pd.DataFrame(json_coords)

    return df_json_coords


def drop_col(df, col_nb):
    '''
    Drops every nth column from a DataFrame.

    INPUTS:
    - df: dataframe. The DataFrame from which columns will be dropped.
    - col_nb: int. The column number to drop.

    OUTPUT:
    - dataframe: DataFrame with dropped columns.
    '''

    idx_col = list(range(col_nb-1, df.shape[1], col_nb)) 
    df_dropped = df.drop(idx_col, axis=1)
    df_dropped.columns = range(df_dropped.columns.size)
    return df_dropped


def vert_speed(df, axis='y'):
    '''
    Calculate the vertical speed of a DataFrame along a specified axis.

    Parameters:
    - df: dataframe. DataFrame of 2D coordinates.
    - axis (str): The axis along which to calculate the speed. Default is 'y'.

    OUTPUT:
    - DataFrame: The DataFrame containing the vertical speed values.
    '''

    axis_dict = {'x':0, 'y':1, 'z':2}
    df_diff = df.diff()
    df_diff = df_diff.fillna(df_diff.iloc[1]*2)
    df_vert_speed = pd.DataFrame([df_diff.loc[:, 2*k + axis_dict[axis]] for k in range(int(df_diff.shape[1] / 2))]).T # modified ( df_diff.shape[1]*2 to df_diff.shape[1] / 2 )
    df_vert_speed.columns = np.arange(len(df_vert_speed.columns))
    return df_vert_speed


def interpolate_zeros_nans(col, kind):
    '''
    Interpolate missing points (of value nan)

    INPUTS
    - col: pandas column of coordinates
    - kind: 'linear', 'slinear', 'quadratic', 'cubic'. Default 'cubic'

    OUTPUT
    - col_interp: interpolated pandas column
    '''
    
    mask = ~(np.isnan(col) | col.eq(0)) # true where nans or zeros
    idx_good = np.where(mask)[0]
    try: 
        f_interp = interpolate.interp1d(idx_good, col[idx_good], kind=kind, bounds_error=False)
        col_interp = np.where(mask, col, f_interp(col.index))
        return col_interp 
    except:
        # print('No good values to interpolate')
        return col


def time_lagged_cross_corr(camx, camy, lag_range, show=True):
    '''
    '''

    if isinstance(lag_range, int):
        lag_range = [-lag_range, lag_range]

    pearson_r = [camx.corr(camy.shift(lag)) for lag in range(lag_range[0], lag_range[1])]
    offset = int(np.floor(len(pearson_r)/2)-np.argmax(pearson_r))
    if not np.isnan(pearson_r).all():
        max_corr = np.nanmax(pearson_r)

        if show:
            f, ax = plt.subplots(2,1)
            # speed
            camx.plot(ax=ax[0], label = f'ref cam')
            camy.plot(ax=ax[0], label = f'compared cam')
            ax[0].set(xlabel='Frame', ylabel='Speed (px/frame)')
            ax[0].legend()
            # time lagged cross-correlation
            ax[1].plot(list(range(lag_range[0], lag_range[1])), pearson_r)
            ax[1].axvline(np.ceil(len(pearson_r)/2) + lag_range[0],color='k',linestyle='--')
            ax[1].axvline(np.argmax(pearson_r) + lag_range[0],color='r',linestyle='--',label='Peak synchrony')
            plt.annotate(f'Max correlation={np.round(max_corr,2)}', xy=(0.05, 0.9), xycoords='axes fraction')
            ax[1].set(title=f'Offset = {offset} frames', xlabel='Offset (frames)',ylabel='Pearson r')
            
            plt.legend()
            f.tight_layout()
            plt.show()
    else:
        max_corr = 0
        offset = 0
        if show:
            # print('No good values to interpolate')
            pass

    return offset, max_corr


def apply_offset(json_dir, offset_cam):
    json_files_names = fnmatch.filter(os.listdir(os.path.join(json_dir)), '*.json')
    json_files_names = sort_stringlist_by_last_number(json_files_names)
    json_files_path = [os.path.join(json_dir, j_f) for j_f in json_files_names]
    [os.rename(f, f+'.del') for f in json_files_path[:offset_cam]]


def reset_offset(json_dir):
    '''
    Reset offset by renaming .json.del files to .json

    INPUTS:
    - json_dir: str. The directory path containing the JSON files.

    OUTPUT:
    - Renamed files in the directory.
    '''

    del_files_names = fnmatch.filter(os.listdir(os.path.join(json_dir)), '*.json.del')
    del_files_path = [os.path.join(json_dir, f) for f in del_files_names]
    [os.rename(f, f[:-4]) for f in del_files_path]


def synchronize_cams_all(config_dict):
    '''
    
    '''
    
    # Get parameters from Config.toml
    project_dir = config_dict.get('project').get('project_dir')
    pose_dir = os.path.realpath(os.path.join(project_dir, 'pose'))
    pose_model = config_dict.get('pose').get('pose_model')
    fps =  config_dict.get('project').get('frame_rate')
    reset_sync = config_dict.get('synchronization').get('reset_sync') 
    display_sync_plots = config_dict.get('synchronization').get('display_sync_plots')
    keypoints_to_consider = config_dict.get('synchronization').get('keypoints_to_consider')
    approx_time_maxspeed = config_dict.get('synchronization').get('approx_time_maxspeed') 

    lag_range = 500 # frames
    min_conf = 0.4
    filter_order = 4
    filter_cutoff = 6

    # Retrieve keypoints from model
    try: # from skeletons.py
        model = eval(pose_model)
    except:
        try: # from Config.toml
            model = DictImporter().import_(config_dict.get('pose').get(pose_model))
            if model.id == 'None':
                model.id = None
        except:
            raise NameError('Model not found in skeletons.py nor in Config.toml')
    keypoints_ids = [node.id for _, _, node in RenderTree(model) if node.id!=None]
    keypoints_names = [node.name for _, _, node in RenderTree(model) if node.id!=None]

    # List json files
    pose_listdirs_names = next(os.walk(pose_dir))[1]
    pose_listdirs_names = sort_stringlist_by_last_number(pose_listdirs_names)
    json_dirs_names = [k for k in pose_listdirs_names if 'json' in k]
    json_dirs = [os.path.join(pose_dir, j_d) for j_d in json_dirs_names] # list of json directories in pose_dir
    nb_frames_per_cam = [len(fnmatch.filter(os.listdir(os.path.join(json_dir)), '*.json')) for json_dir in json_dirs]
    cam_nb = len(json_dirs)
    cam_list = list(range(cam_nb))
    
    # Reset previous synchronization attempts
    if reset_sync:
        [reset_offset(json_dir) for json_dir in json_dirs]
    
    # Synchronize cameras
    else:
        # Determine frames to consider for synchronization
        if isinstance(approx_time_maxspeed, list): # search around max speed
            approx_frame_maxspeed = [int(fps * t) for t in approx_time_maxspeed]
            nb_frames_per_cam_excludingdel = [len(fnmatch.filter(os.listdir(os.path.join(json_dir)), '*.json'))-len(fnmatch.filter(os.listdir(os.path.join(json_dir)), '*.json.del')) for json_dir in json_dirs]
            search_around_frames = [[a-lag_range if a-lag_range>0 else 0, a+lag_range if a+lag_range<nb_frames_per_cam_excludingdel[i] else nb_frames_per_cam_excludingdel[i]] for i,a in enumerate(approx_frame_maxspeed)]
        elif approx_time_maxspeed == 'auto': # search on the whole sequence (slower if long sequence)
            search_around_frames = [[0, nb_frames_per_cam[i]] for i in range(cam_nb)]
        else:
            raise ValueError('approx_time_maxspeed should be a list of floats or "auto"')

        # Extract, interpolate, and filter keypoint coordinates
        df_coords = []
        b, a = signal.butter(filter_order/2, filter_cutoff/(fps/2), 'low', analog = False) 
        for i, json_dir in enumerate(json_dirs):
            df_coords.append(convert_json2pandas(json_dir, min_conf=min_conf, frame_range=search_around_frames[i]))
            df_coords[i] = drop_col(df_coords[i],3) # drop likelihood
            if keypoints_to_consider == 'right':
                kpt_indices = [i for i,k in zip(keypoints_ids,keypoints_names) if k.startswith('R') or k.startswith('right')]
                kpt_indices = np.sort(np.concatenate([np.array(kpt_indices)*2, np.array(kpt_indices)*2+1]))
                df_coords[i] = df_coords[i][kpt_indices]
            elif keypoints_to_consider == 'left':
                kpt_indices = [i for i,k in zip(keypoints_ids,keypoints_names) if k.startswith('L') or k.startswith('left')]
                kpt_indices = np.sort(np.concatenate([np.array(kpt_indices)*2, np.array(kpt_indices)*2+1]))
                df_coords[i] = df_coords[i][kpt_indices]
            elif isinstance(keypoints_to_consider, list):
                kpt_indices = [i for i,k in zip(keypoints_ids,keypoints_names) if k in keypoints_to_consider]
                kpt_indices = np.sort(np.concatenate([np.array(kpt_indices)*2, np.array(kpt_indices)*2+1]))
                df_coords[i] = df_coords[i][kpt_indices]
            elif keypoints_to_consider == 'all':
                pass
            else:
                raise ValueError('keypoints_to_consider should be "all", "right", "left", or a list of keypoint names.\n\
                                If you specified keypoints, make sure that they exist in your pose_model.')

            df_coords[i] = df_coords[i].apply(interpolate_zeros_nans, axis=0, args = ['linear'])
            df_coords[i] = df_coords[i].bfill().ffill()
            df_coords[i] = pd.DataFrame(signal.filtfilt(b, a, df_coords[i], axis=0))

        # Save keypoint coordinates to pickle
        # with open(os.path.join(pose_dir, 'coords'), 'wb') as fp:
        #     pk.dump(df_coords, fp)
        # with open(os.path.join(pose_dir, 'coords'), 'rb') as fp:
        #     df_coords = pk.load(fp)

        # Compute sum of speeds
        df_speed = []
        sum_speeds = []
        for i in range(cam_nb):
            df_speed.append(vert_speed(df_coords[i]))
            sum_speeds.append(abs(df_speed[i]).sum(axis=1))
            # nb_coord = df_speed[i].shape[1]
            # sum_speeds[i][ sum_speeds[i]>vmax*nb_coord ] = 0
            sum_speeds[i] = pd.DataFrame(signal.filtfilt(b, a, sum_speeds[i], axis=0)).squeeze()

        # Compute offset for best synchronization:
        # Highest correlation of sum of absolute speeds for each cam compared to reference cam
        ref_cam_id = nb_frames_per_cam.index(min(nb_frames_per_cam)) # ref cam: least amount of frames
        ref_frame_nb = len(df_coords[ref_cam_id])
        lag_range = int(ref_frame_nb/2)
        cam_list.pop(ref_cam_id)
        offset = []
        for cam_id in cam_list:
            offset_cam, max_corr_cam = time_lagged_cross_corr(sum_speeds[ref_cam_id], sum_speeds[cam_id], lag_range, show=display_sync_plots)
            print(f'Camera {ref_cam_id} and camera {cam_id} have a max correlation of {round(max_corr_cam, 2)} with an offset of {offset_cam} frames.')
            apply_offset(json_dirs[cam_id], offset_cam)
            offset.append(offset_cam)
        offset.insert(ref_cam_id, 0)