#!/usr/bin/env bash

# See the README for instructions setting up.
# ./make-anonymous-key KEYNAME

# figure out which directory we are stored in
# https://stackoverflow.com/questions/59895/can-a-bash-script-tell-what-directory-its-stored-in
_GITNONYMOUS_SRC="${BASH_SOURCE[0]}"
# resolve $_GITNONYMOUS_SRC until the file is no longer a symlink
while [ -h "$_GITNONYMOUS_SRC" ]; do
  dir="$( cd -P "$( dirname "$_GITNONYMOUS_SRC" )" && pwd )"
  _GITNONYMOUS_SRC="$(readlink "$_GITNONYMOUS_SRC")"
  # if $_GITNONYMOUS_SRC was a relative symlink, we need to resolve it
  # relative to the path where the symlink file was located
  [[ $_GITNONYMOUS_SRC != /* ]] && _GITNONYMOUS_SRC="$DIR/$_GITNONYMOUS_SRC"
done
dir="$( cd -P "$( dirname "$_GITNONYMOUS_SRC" )" && pwd )"
unset _GITNONYMOUS_SRC

gitnonymous_usage () {
  if [ "$1" != "" ]
  then
    gitnonymous_error "Don't call this script directly. 'Source' it instead."
  fi
  echo "Usage:"
  echo ". ${BASH_SOURCE[0]} KEYNAME"
}

# function to throw error messages
gitnonymous_error () {
  >&2 echo $@
}

# when we are missing a config file call this
gitnonymous_error_missing () {
  gitnonymous_error $@
  gitnonymous_error "To create it run: ${dir}/gitnonymous-setup ${keyname}"
}

# Make sure we were called with 'source' instead of directly
if [[ "${BASH_SOURCE[0]}" != "$0" ]]
then
  # check for the keyname parameter
  if [ "$1" = "" ]
  then
    gitnonymous_usage
    return 1
  else
    # set the key and the config file
    keyname="${1}"
    rootdir="${HOME}/.gitnonymous-${keyname}"
    configfile="${rootdir}/config"
    sshdir="${rootdir}/ssh"
    oldenvfile="${rootdir}/previous-environment"
    sshagentsocket="${sshdir}/.ssh-agent-$$"
    
    if [ "$_GITNONYMOUS" != "" ]
    # toggle everything off again
    then
      echo "Unsetting gitnonymous environment ${keyname}"
      # kill our special ssh agent
      ssh-agent -k
      # restore the command prompt
      export PS1="${_GITNONYMOUS_OLDPS1}"
      unset GIT_COMMITTER_EMAIL
      unset GIT_COMMITTER_NAME
      unset GIT_AUTHOR_EMAIL
      unset GIT_AUTHOR_NAME
      unset GIT_SSH
      unset GIT_PROXY_COMMAND
      unset ALL_PROXY
      unset TZ
      # restore any GIT_ environment variables set before
      . "${oldenvfile}"
      # unset our environment variables we set
      unset _GITNONYMOUS_OLDPS1
      unset _GITNONYMOUS
      unalias "gitnonymous-exit"
      echo "Done unsetting ${keyname}."
    else
      # add our custom local SSH key (make the key with ./make-anonymous-key)
      if [ -f ${sshdir}/id_rsa -o -f ${sshdir}/identity ]
      then
        # if a stale socket already exists then throw an error
        if [ -f "${sshagentsocket}" ]
        then
          gitnonymous_error "Stale SSH agent socket '${sshagentsocket}' exists."
          gitnonymous_error "You can probably delete it safely and try again."
          return 2
        fi
        # start a new SSH agent just for this session
        eval $(ssh-agent -a "${sshagentsocket}")
        # add the key
        if [ -f ${sshdir}/id_rsa ]
        then
          ssh-add ${sshdir}/id_rsa
        else
          ssh-add ${sshdir}/identity
        fi
      else
        gitnonymous_error_missing "SSH config in ${sshdir} not found!"
        return 3
      fi
      
      # load the user's anonymous GIT settings and environment
      if [ -f "${configfile}" ]
      then
        # save the old GIT values
        export | grep -E "GIT_|ALL_PROXY|TZ" > ${oldenvfile}
        # source the config file
        .  "${configfile}"
      else
        gitnonymous_error_missing "GIT config in ${configfile} not found!"
        return 4
      fi
      
      # trap exit of this shell and kill ssh-agent
      trap 'ssh-agent -k' EXIT
      
      # tell GIT to use our customised anonymous SSH wrapper
      export GIT_SSH="${rootdir}/git-ssh-wrap"
      
      # tell GIT to use the tor proxy for all other traffic
      export GIT_PROXY_COMMAND="${dir}/git-proxy-command"
      export ALL_PROXY="socks5://127.0.0.1:9050"
      
      # make it obvious we're in a special environment
      _GITNONYMOUS_OLDPS1="${PS1}"
      export PS1="${keyname}⚔ ${PS1}"
      export _GITNONYMOUS="${keyname}"

      echo "Run 'gitnonymous-exit' to exit this identity."
      # alias exit command
      alias "gitnonymous-exit"=". ${BASH_SOURCE[0]} ${keyname}"
    fi
  fi
else
  gitnonymous_usage true
  exit 2
fi