ssh

#!/bin/bash

set -e

APP_DIR=$(cd $(dirname $0); pwd)
APP_NAME=$(basename $0)
APP_PID=$$
TMP_DIRNAME='/tmp/ssh-termcolors'

# MCW: Color schemes
# TODO: Label these with comments.
COLORS=(        \
    '#1b0000'   \
    '#001b00'   \
    '#00001b'   \
)

function emit_startup_warning
{
    # MCW: Warning message, since this is *not* the real ssh binary.
    local bold="\033[1m" normal="\033[0m"
    
    echo -e "${bold}Using modified ssh at \`${APP_DIR}/${APP_NAME}'${normal}" && echo
}

function convert_webhex
{
    local webhex=${1:1}
    local component_width=2
    local is_16_bit=
    
    # MCW: lets us deal with 8-bit color values
    if [ ${#webhex} -ge 12 ]; then
        component_width=4
        is_16_bit="true"
    fi
    
    for color in red green blue; do
        local component=${webhex:0:component_width}
        
        if [ $is_16_bit ]; then
            local ${color}=$(( 0x${component} ))
        else
            local ${color}=$(( 0xFFFF * 0x${component} / 0xFF ))
        fi
        
        webhex=${webhex:component_width}
    done
    
    printf "%s,%s,%s" $red $green $blue
}

function set_termcolor
{
    local termcolor=$(convert_webhex $1)
    
    osascript -e "tell front window of app \"Terminal\" to set background color to {${termcolor}}"
}

function ssh_termcolor
{
    local ssh_hostname=$1 parent_pid=$2
    local current_termcolor="#000000"
    
    if [ $(find /tmp/ -name ssh-termcolor-*-${ssh_hostname}) ]; then
        local termcolor_filename=$(find /tmp/ -name ssh-termcolor-*-${ssh_hostname} | head -n 1)
        current_termcolor=$(cat ${termcolor_filename})
    else
        local termcolor_host_count=$(( $(       \
            find /tmp/ -name ssh-termcolor-*    \
        |   sed -E 's/[0-9]+-//'                \
        |   uniq                                \
        |   wc -l                               \
        ) ))
        
        current_termcolor=${COLORS[$(( ${termcolor_host_count} % ${#COLORS[@]} ))]}
    fi
    
    echo -n "${current_termcolor}" > /tmp/ssh-termcolor-${parent_pid}-${ssh_hostname}
    set_termcolor ${current_termcolor}
}

function ssh_connect
{
    emit_startup_warning
    
    # `ssh' will exit with a nonzero status in the event of
    # a connection being terminated by the host, etc.
    set +e
        ssh -o 'PermitLocalCommand yes' -o "LocalCommand $0 --set-termcolor '%h' --parent-pid '$$'" $@
    
        rm -f /tmp/ssh-termcolor-$$*
        set_termcolor '#000000'
    set -e
}

# shows the usage info for the real ssh
if [ -z "$1" ]; then
    ssh; exit 1
fi

# special invocation as:
#   ssh --set-termcolor <color> --parent-pid <pid>
# TODO: Fix this so that the order of arguments doesn't matter.
if [ '--set-termcolor' = "$1" ]; then
    ssh_termcolor $2 $4
else
    ssh_connect $@
fi