# Functions.
_agent_prompt_command() {
  hash ssh-add >/dev/null 2>&1 && {
    local SOCK
    declare -g _SSH_PROMPT_ERROR_ISSUED
    # Check the ssh agent socket is still alive.
    ssh-add -l >/dev/null 2>&1
    if (($? >= 2)); then
      # Auth socket has become unusable, search for a new one.
      SOCK="$(_find_agent_sock)"
      if ((${PIPESTATUS[0]} == 0)); then
        export SSH_AUTH_SOCK="$SOCK"
        _SSH_PROMPT_ERROR_ISSUED=0
        echo "Connected to alternate ssh-agent - you may need to re-add keys."
      else
        if [[ -z "$(egrep -v '^$' ~/.ssh/agents)" ]]; then
          ((${_SSH_PROMPT_ERROR_ISSUED:-0} == 0)) && {
            echo "$(tput setaf 1 || tput AF 1)Lost connection to ssh-agent - no alternate available!$(tput op)"
            unset SSH_AUTH_SOCK
            _SSH_PROMPT_ERROR_ISSUED=1
          }
        else
          ((${_SSH_PROMPT_ERROR_ISSUED:-0} == 0)) && {
            echo "$(tput setaf 1 || tput AF 1)Lost connection to ssh-agent - failed to connect to new agent!$(tput op)"
            unset SSH_AUTH_SOCK
            _SSH_PROMPT_ERROR_ISSUED=1
          }
        fi
      fi
    else
      _SSH_PROMPT_ERROR_ISSUED=0
    fi
    unset SOCK
  }
}

_clean_agent_socks() {
  local I SSH_AUTH_SOCK
  # Go through the array of sockets and validate each one.
  for ((I = 0; I < ${#SOCKS[@]}; I++)); do
    SSH_AUTH_SOCK="${SOCKS[$I]}" ssh-add -l >/dev/null 2>&1
    (($? >= 2)) && {
      unset SOCKS[$I]
    }
  done
}

_find_agent_sock() {
  local I IFS=$'\n' REPLY SOCKS=() SSH_AUTH_SOCK="$SSH_AUTH_SOCK"
  # Load the array of sockets, minus the one we know is unusable.
  if ((${BASH_VERSINFO[0]} >= 4)); then
    mapfile -t SOCKS < <(egrep -v "^$SSH_AUTH_SOCK\$" ~/.ssh/agents 2>/dev/null)
  else
    while read -r; do
      SOCKS+=("$REPLY")
    done < <(egrep -v "^$SSH_AUTH_SOCK\$" ~/.ssh/agents 2>/dev/null)
  fi
  # Search backwards through the list to find an active socket.
  for ((I = (${#SOCKS[@]} - 1); I >= 0; I--)); do
    SSH_AUTH_SOCK="${SOCKS[$I]}" ssh-add -l >/dev/null 2>&1
    (($? <= 1)) && [[ ! -z "${SOCKS[$I]}" ]] && {
      printf "%s" "${SOCKS[$I]}"
      return 0
    }
  done
  return 1
}

_pop_agent_sock() {
  local IFS=$'\n' REPLY SOCKS=()
  # Read the current list of auth sockets.
  if ((${BASH_VERSINFO[0]} >= 4)); then
    mapfile -t SOCKS < <(egrep -v "^$SSH_AUTH_SOCK\$" ~/.ssh/agents 2>/dev/null)
  else
    while read -r; do
      SOCKS+=("$REPLY")
    done < <(egrep -v "^$SSH_AUTH_SOCK\$" ~/.ssh/agents 2>/dev/null)
  fi
  # Clean up any dead sockets - this modifies the SOCKS array.
  _clean_agent_socks
  # Write the new list back to disk.
  printf "%s\n" "${SOCKS[@]}" >~/.ssh/agents
  return $?
}

_push_agent_sock() {
  local IFS=$'\n' REPLY SOCKS=()
  # Read the current list of auth sockets.
  if ((${BASH_VERSINFO[0]} >= 4)); then
    mapfile -t SOCKS <~/.ssh/agents
  else
    while read -r; do
      SOCKS+=("$REPLY")
    done <~/.ssh/agents
  fi
  # Clean up any dead sockets - this modifies the SOCKS array.
  _clean_agent_socks
  # Write the new list back to disk.
  printf "%s\n" "${SOCKS[@]}" "$SSH_AUTH_SOCK" >~/.ssh/agents
  return $?
}

# Make bash a little more pleasent - these are valid for all versions.
shopt -s cdspell checkhash checkwinsize cmdhist histappend no_empty_cmd_completion

# Exit the shell on a Ctl+D.
IGNOREEOF=0

# History control.
HISTCONTROL="ignoredups"
HISTFILESIZE=100000
HISTIGNORE="w:bg:bg *:fg:fg *:jobs:exit:pwd:clear:history"
HISTSIZE=-1
HISTTIMEFORMAT="%d/%m/%y %H:%M:%S  "
history -r

# Determine the colour of the username in the prompt.
if (( $(id -u) == 0 )); then
  _COLOUR=1	# Red
else
  _COLOUR=2	# Green
fi

# Version specific set up.
if (( ${BASH_VERSINFO[0]} >= 4 )); then
  # Add to the shopts.
  shopt -s checkjobs dirspell

  # Set the prompts.
  PROMPT_DIRTRIM=2
  # No colour:
  # PS1="[\u@\h] \w ->"
  # Coloured username:
  # PS1="[\[$(tput bold)$(tput setaf $_COLOUR)\]\u\[$(tput sgr0)\]@\h] \w ->"
  # Coloured username + host:
  # PS1="[\[$(tput bold)$(tput setaf $_COLOUR)\]\u\[$(tput sgr0)\]@\[$(tput bold)$(tput setaf 3)\]\h\[$(tput sgr0)\]] \w ->"
  # Coloured username + host + directory:
  PS1="[\[$(tput bold)$(tput setaf $_COLOUR)\]\u\[$(tput sgr0)\]@\[$(tput bold)$(tput setaf 3)\]\h\[$(tput sgr0)\]] \[$(tput bold)$(tput setaf 4)\]\w\[$(tput sgr0)\] ->"
else
  # Set the prompts.
  # No colour:
  # PS1="[\u@\h] \$(echo \"\${PWD/#\$HOME/~}\" | awk -F/ '{if (NF>3) {printf \".../\" \$(NF-1) \"/\" \$NF} else {printf \$0}}') ->"
  # Coloured username:
  # PS1="[\[$(tput bold)$(tput setaf $_COLOUR)\]\u\[$(tput sgr0)\]@\h] \$(echo \"\${PWD/#\$HOME/~}\" | awk -F/ '{if (NF>3) {printf \".../\" \$(NF-1) \"/\" \$NF} else {printf \$0}}') ->"
  # Coloured username + host:
  # PS1="[\[$(tput bold)$(tput setaf $_COLOUR)\]\u\[$(tput sgr0)\]@\[$(tput bold)$(tput setaf 3)\]\h\[$(tput sgr0)\]] \$(echo \"\${PWD/#\$HOME/~}\" | awk -F/ '{if (NF>3) {printf \".../\" \$(NF-1) \"/\" \$NF} else {printf \$0}}') ->"
  # Coloured username + host + directory:
  PS1="[\[$(tput bold)$(tput setaf $_COLOUR)\]\u\[$(tput sgr0)\]@\[$(tput bold)$(tput setaf 3)\]\h\[$(tput sgr0)\]] \[$(tput bold)$(tput setaf 4)\]\$(echo \"\${PWD/#\$HOME/~}\" | awk -F/ '{if (NF>3) {printf \".../\" \$(NF-1) \"/\" \$NF} else {printf \$0}}')\[$(tput sgr0)\] ->"
fi
unset _COLOUR

# Set the debugger prompt.
# PS4="+(\\\$? = \$?) \${BASH_SOURCE##*/}\${FUNCNAME:+(\$FUNCNAME)}:\$LINENO: "
PS4="+(\[\e[33m\]\\\$? = \$?\[$(tput sgr0)\]) \[$(tput bold)$(tput setaf 4)\]\${BASH_SOURCE##*/}\[$(tput sgr0)\]\${FUNCNAME:+(\[$(tput bold)$(tput setaf 2)\]\$FUNCNAME\[$(tput sgr0)\])}:\[$(tput bold)$(tput setaf 1)\]\$LINENO\[$(tput sgr0)\]: "

# Platform specific set up.
_PLATFORM="$(uname -s)"
if [[ "$_PLATFORM" = "Linux" ]]; then
  # Linux specific aliases.
  hash ftpwho >/dev/null 2>&1 && alias ftpwho='ftpwho -v'
  hash iftop >/dev/null 2>&1 && alias iftop='TERM=vt100 iftop'
  hash last less >/dev/null 2>&1 && alias laston='last -a | less'
  hash ls >/dev/null 2>&1 && alias ls='ls -bFv --color=auto'
  hash minicom >/dev/null 2>&1 && alias minicom='minicom -m -c on'
  hash mkpasswd >/dev/null 2>&1 && alias pwgen='mkpasswd -m sha512crypt'
  hash pine >/dev/null 2>&1 && alias pine='pine -p "{mail.open-source.co.uk/Service=IMAP/User=darren@afterdark.org.uk/TLS/NoValidate-Cert/NoRsh}.pinerc"'
  hash pinfo >/dev/null 2>&1 && alias info='pinfo'
  hash ping >/dev/null 2>&1 && alias ping='ping -b'

  # Linux specific functions.
  psgrep() {
    ps -auwwx | egrep "(RSS|$1)"
  }
elif [[ "$_PLATFORM" = "Darwin" ]]; then
  # Darwin specific aliases.
  hash df >/dev/null 2>&1 && alias df='df -P'
  hash ls >/dev/null 2>&1 && alias ls='ls -bFG'
  hash top >/dev/null 2>&1 && alias top='top -o cpu -S'
else
  echo "${BASH_SOURCE##*/}: unsupported platform: $_PLATFORM" >&2
fi
unset _PLATFORM

# Common aliases.
hash bc >/dev/null 2>&1 && alias bc='bc -lq'
hash curl >/dev/null 2>&1 && alias pastebin="curl -F 'sprunge=<-' http://sprunge.us"
hash diff >/dev/null 2>&1 && alias diff='diff -u'
hash egrep >/dev/null 2>&1 && alias egrep='egrep --color=auto'
hash fgrep >/dev/null 2>&1 && alias fgrep='fgrep --color=auto'
hash grep >/dev/null 2>&1 && alias grep='grep --color=auto'
hash screen >/dev/null 2>&1 && alias screen='screen -Ua'