#!/bin/sh
# set -x
#
# Write image to disk.
# USAGE : ./prepare-disk /path/to/image.img
#

function accept {
    echo
    read -p "▶ $1 (yN) " -n 1 -r
    echo
    echo
    if [[ $REPLY =~ ^[Yy]$ ]]
    then
        return 0
    fi
    return 1
}

function log {
    echo " $1"
}

function write {
    DISK=$1
    log "☕  Writing $IMAGE to disk - press Ctrl+T to see progress"
    CMD="sudo dd if=$IMAGE of=$DISK bs=8m"
    echo `eval $CMD`
}

function unmount {
    DISK=$1
    log "🔨  Unmount $DISK"
    diskutil unmountDisk $DISK
}

function launch {
    DISK=$1
    if accept " ⚠  Reformat $DISK with $IMAGE ?"
    then
        log "🚀  Launch operations on $DISK"
        unmount $DISK
        write $DISK
        unmount $DISK
        log "👌  Done !"
    fi
}

function listDevices {
    diskutil list | grep /dev/disk -A 2 | grep "0:"
}

function getDiskBySize {
    echo `eval "diskutil list | grep '*$1' | grep -oE \"[^ ]+\$\""`
}

function guessDevice {
    DEVICE=$(getDiskBySize "4.0 GB")
    if [[ ! $DEVICE ]]
    then
        DEVICE=$(getDiskBySize "8.0 GB")
    fi
    if [[ ! $DEVICE ]]
    then
        DEVICE=$(getDiskBySize "7.9 GB")
    fi
    if [[ ! $DEVICE ]]
    then
        DEVICE=$(getDiskBySize "7.7 GB")
    fi
    if [[ ! $DEVICE ]]
    then
        DEVICE=$(getDiskBySize "2.0 GB")
    fi
    if [[ $DEVICE ]]
    then
        # add /dev/r for raw access
        DEVICE="/dev/r$DEVICE"
    fi
    echo $DEVICE
}

IMAGE=$1

if [[ ! $IMAGE ]]
then
    echo 'USAGE: prepare-disk /path/to/image.img'
    exit 1
fi

listDevices
log "Guess device..."
DEVICE=$(guessDevice)

if [[ ! $DEVICE ]]
then
    echo '😡  No disk detected, use prepare-disk.sh /dev/XXX'
    echo '😡  Use diskutil list to check the device'
    exit 1
else
    launch $DEVICE
fi