#!/bin/bash

slog(){
	echo "$1" | sudo -u sats tee -a /home/sats/satsd/log/update.log > /dev/null;
}

HSALT="***SALT***";
HPEPPER="***PEPPER***";

slog ">>> Dynamic Wireless Credentials";

# [1] Wifi scan for "SATS_*" APs
#========================================================#

# (1) Get interface name #
IFACE=`ifconfig | grep -P "^w" | awk '{print $1}'`;

# (2) Get nearest AP matching "SATS_*" and extract HASH #
AP_HASH=`sudo iwlist wlan0 scan | grep -P "^\s*ESSID:\"SATS_.+\"\s*$" | sed 's/^[ \t]*ESSID:"SATS_//' | sed 's/"[ \t]*$//'`;

# (3) Manage no AP found #
test `echo -ne $AP_HASH | wc -l` -eq 0 && slog "no AP found" && exit;



# [2] Calculate WIFI PASS from SSID hash
#========================================================#
PASS=`echo -ne "$HPEPPER$(echo -n "${HSALT}${AP_HASH}" | sha512sum | sed 's/[ \t]*-$//')" | sha512sum | sed 's/[ \t]*-//'`;


# [3] Update 'wpa_supplicant.conf'
#========================================================#

# (1) Update SSID #
sudo cat /etc/wpa_supplicant/wpa_supplicant.conf | sed "s/^[ \t]*ssid=.*$/\tssid=\"SATS_$AP_HASH\"/" | sudo tee /etc/wpa_supplicant/wpa_supplicant.tmp;

# (2) Update PASS #
sudo cat /etc/wpa_supplicant/wpa_supplicant.tmp  | sed "s/^[ \t]*psk=.*$/\tpsk=\"$PASS\"/"           | sudo tee /etc/wpa_supplicant/wpa_supplicant.conf;

# (3) Remove tmp file #
sudo rm /etc/wpa_supplicant/wpa_supplicant.tmp;

slog "<<< Done";