#!/usr/bin/env python3
import sys
import os
import time
import re
from select import select
from glob import glob
from subprocess import check_output, STDOUT, PIPE, Popen, TimeoutExpired

IMAGES_HOST = 'l_samenv@linse-c'
IMAGES_DIR = 'boxes/rpi_images'
IMAGES_PAT = '*.lz4'

extdisks = {}


def prt(text):
    print(time.strftime('%H:%M:%S'), text)


def cmd(command, verbose=False):
    if verbose:
        print(f'> {command}')
    return check_output(command.split(), stderr=STDOUT).decode('latin-1')


def get_disks():
    return [line for line in cmd('lsblk -d').split('\n') if line]


def rpiboot():
    lines = []
    with Popen(['sudo', './rpiboot', '-d', 'mass-storage-gadget64'], stdout=PIPE) as p:
        tmo = 1
        t = 0
        while select([p.stdout], [], [], tmo)[0]:
            rawline = p.stdout.readline()
            if not rawline:
                return tmo != 1
            line = rawline.decode('latin-1').strip()
            print(line)
            if lines is None:
                pass # print(line)
            elif 'Waiting' in line:
                tmo = 10
                lines.append(line)
                t = time.time()
            elif tmo == 1:
                lines.append(line)
            else:
                print('\n'.join(lines))
                print(line)
                lines = None
        else:
            p.terminate()
            return False


def list_external():
    print('--- external disks:')
    for disk, info in extdisks.items():
       print(disk, info)


rescue = """
Remark: not all cables might work.
Example on Markus Mac:
- does not work: black USB C to USB C cable
- works: white USB A to USB C cable plugged into docking station.

Please unpower the box with compute module,
start this script again and put power immediately."""


def wait_disks(prevset, delay):
    for i in range(int(delay)):
        disks = get_disks()
        diskset = set(disks)
        if diskset != prevset:
            print('\n'.join(disks))
            if i:
                print('')
            return diskset - prevset
        print('.', end='')
        time.sleep(1)
    return None


def find_raspi(kind='emmc'):
    input('make sure device is not connected [confirm]')
    prevset = set(get_disks())
    input('now connect [confirm]')
    disks = wait_disks(prevset, 5)
    if not disks:
        print('can not yet detect disk, try to run rpiboot')
        print('if is blocked at "Waiting for BCM...", turn off and on power of target rpi')
        # cmd('sudo ./rpiboot -d mass-storage-gadget64')
        rpiboot()
        disks = wait_disks(prevset, 15)
        if not disks:
            raise RuntimeError('raspi disk does not appear')
    return disks


def write_image(kind):
    proposed = [v.split()[0] for v in find_raspi(kind)]
    list_external()
    if len(proposed) == 1:
        dev = proposed[0]
    elif len(proposed) > 1:
        if kind == 'emmc':
            print('several potential devices:', proposed)
            return
        dev = input('select device to write to {" ".join(proposed)}: ')
    else:
        print('not found')
        return
    images = check_output(['sudo', '-u', 'l_samenv', 'ssh', IMAGES_HOST, f'cd {IMAGES_DIR} ; ls {IMAGES_PAT}']).decode('latin-1').split('\n')
    for file in sorted(images):
        print(file)
    print('')
    image = input(f'select image to write to {dev} [{file}]: ') or file
    prt(f'unmount {dev} ...')
    print('you may be prompted for your account password for sudo')
    os.system(f'sudo umount /dev/{dev}')
    print('')
    prt('get, uncompress and write... (takes about 15 min)')
    os.system(f'ssh {IMAGES_HOST} "dd if={IMAGES_DIR}/{image} bs=512k" | lz4 -d | sudo dd of=/dev/{dev} bs=512k')
    prt('unmount bootfs')
    for _ in range(3):
        if os.path.exists('/Volumes/bootfs'):
           prt('unmount bootfs')
           os.system('sudo umount bootfs')
           break
        time.sleep(1.0)
    prt('done')
    os.system(f'sudo umount /dev/{dev}')

if len(sys.argv) == 2:
    write_image(sys.argv[1])
else:
    print("""
Usage:

> write_to emmc   # write to compute module using PoE board"
> write_to sd     # write to sd card

""")