#!/usr/bin/env python


import sys, os
import argparse, json
import random, re, subprocess, shutil, time
import datetime


"""
" CLI
"""

parser = argparse.ArgumentParser(
    prog='wallpaper',
    description='Cycle through wallpapers'
)

parser.add_argument(
    '--config',
    required=True,
    help='{"<weight>": { "find": "<path>", "exclude": "<regex>" }, "<weight>":...}'
)

parser.add_argument(
    '--interval',
    default=600
)

parser.add_argument(
    '--unique',
    default=False
)

parser.add_argument(
    '--consider_daylight',
    default=False
)

parser.add_argument(
    '--brightness_threshold',
    default=0.35
)

parser.add_argument(
    '--window_manager',
    default='sway'
)

args = parser.parse_args()

config = json.loads(args.config)


if args.window_manager == 'sway':
    if shutil.which('swaybg') is None:
        sys.exit('swaybg not found')
elif args.window_manager == 'i3':
    if shutil.which('feh') is None:
        sys.exit('feh not found')

if args.consider_daylight and shutil.which('sunwait') is None:
    sys.exit('sunwait not found')
if args.consider_daylight and shutil.which('identify') is None:
    sys.exit('identify not found')


"""
" Program
"""

# set variables for --unique flag
already_selected_file_paths = {}
if args.unique:
    for weight, config_item in config.items():
        config[weight]['id'] = hash(json.dumps(config_item, sort_keys=True))
        already_selected_file_paths[config_item['id']] = []

# set variables for --consider_daylight flag
location = {}
if args.consider_daylight:
    location = {
        'latitude': float(subprocess.run(['pass', 'latitude'], capture_output=True, text=True).stdout),
        'longitude': float(subprocess.run(['pass', 'longitude'], capture_output=True, text=True).stdout),
    }

# run the loop
running_bg_process = None
while True:
    probability_number = random.randrange(start=1, stop=100, step=1)

    # select config to use based on args.config
    # see https://stackoverflow.com/questions/16489449/select-element-from-array-with-probability-proportional-to-its-value/16490300#16490300
    selected_config = {}
    accumulative = 0
    for weight, config_item in config.items():
        lower_bound = accumulative
        accumulative += int(weight)
        upper_bound = accumulative

        if lower_bound <= probability_number and probability_number <= upper_bound:
            selected_config = config_item
            break

    # build list of file paths to choose from
    found_file_paths = []
    for dirpath, dirnames, filenames in os.walk(os.path.expandvars(selected_config['find'])):
        for filename in filenames:
            found_file_paths.append(f'{dirpath}/{filename}')

    if 'exclude' in selected_config.keys():
        found_file_paths = list(filter(
            lambda file_path: (not re.match(os.path.expandvars(selected_config['exclude']), file_path)),
            found_file_paths
        ))

    if args.unique:
        # filter file paths from already selected paths
        filtered_file_paths = [
            item
            for item in found_file_paths
            if item not in already_selected_file_paths[selected_config['id']]
        ]

        # if we cycled through all of them, repeat
        if not filtered_file_paths:
            filtered_file_paths = found_file_paths
            already_selected_file_paths[selected_config['id']] = []

        found_file_paths = filtered_file_paths

    # select file
    selected_file_path = random.choice(found_file_paths)

    if args.consider_daylight:
        daytime_process = subprocess.run(['sunwait', 'poll', '{0}N'.format(location['latitude']), '{0}E'.format(location['longitude'])], capture_output=True, text=True)
        daytime = daytime_process.stdout.strip()

        if daytime == 'NIGHT':
            tries = 0
            while True:
                selected_file_path = random.choice(found_file_paths)

                identify_process = subprocess.run(['identify', '-format', '%[fx:mean]', selected_file_path], capture_output=True, text=True)
                brightness = float(identify_process.stdout)
                if brightness < float(args.brightness_threshold): # non-bright image
                    break
                else:
                    # remove identified bright image from possible selections
                    found_file_paths.remove(selected_file_path)

                    if args.unique:
                        already_selected_file_paths[selected_config['id']].append(selected_file_path)

                # can't find suitable image
                tries += 1
                if tries >= len(found_file_paths) - 1:
                    if args.unique:
                        already_selected_file_paths[selected_config['id']] = []

                    break

    if args.unique:
        already_selected_file_paths[selected_config['id']].append(selected_file_path)

    # run bg command
    if args.window_manager == 'sway':
        bg_cmd = ['swaybg', '-i', selected_file_path, '-m', 'fill']
    elif args.window_manager == 'i3':
        bg_cmd = ['feh', '--bg-fill', selected_file_path]

    replacing_process = subprocess.Popen(bg_cmd)

    # wait until new instance of swaybg has booted up properly
    time.sleep(5)

    # kill the previous process
    # the new swaybg process takes its place automatically
    if running_bg_process:
        running_bg_process.terminate()

    # set running process for next iteration
    running_bg_process = replacing_process

    # wait $INTERVAL seconds
    time.sleep(int(args.interval))