##
# Prompt that can be customized through vcs_info
#

autoload -Uz add-zle-hook-widget add-zsh-hook vcs_info

# Standardized exit codes. See `man 3 sysexits`.
if [[ ${(t)sysexits} != *readonly* ]]; then
  # Avoid error in case this has been set already.
  readonly -ga sysexits=(
      USAGE
      DATAERR
      NOINPUT
      NOUSER
      NOHOST
      UNAVAILABLE
      SOFTWARE
      OSERR
      OSFILE
      CANTCREAT
      IOERR
      TEMPFAIL
      PROTOCOL
      NOPERM
      CONFIG
  )
fi

# Prompt segments
readonly -gHA _prompt_vcs_defaults=(
    start:chpwd     $'\n%B%F{blue}%~%%b%f/\n'
    start:left      $'%%(?,%F{green},%F{red}%v%k\n%B%%S)%#%%b%f%%s '
    start:right     '%B%F{blue}%n%b%f%k@%F{magenta}%m%f'
    start:staged    '%B%F{green}+%b%f'
    start:unstaged  '%B%F{red}*%b%f'
    start:action    '%B%F{red}%a%%b%f'
    start:branch    '%B%F{cyan}%b%%b%f'
    start:repo      '|%B%F{blue}%r%%b%f'
    cont:indent     '  '
    cont:left       ''
    cont:right      '%F{red}%^%f'
)

prompt_vcs_help() {
  print -r -- \
"This prompt theme can by customized by copy-pasting any of the code below to
your .zshrc file and editing it there:'

  # For each of these,
  # * the first string is used for \$PS1 after changing dirs,
  # * the second string is used for \$PS1 otherwise, and
  # * the third string is used for \$RPS1 and updated asynchronously.
  # In these, %v expands to the name (if any) & number of the last exit code.
  zstyle ':vcs_info:*:prompt_vcs:*' nvcsformats \
      "${${:-$_prompt_vcs_defaults[start:chpwd]$_prompt_vcs_defaults[start:left]}//'%%'/%}" \
      "${_prompt_vcs_defaults[start:left]//'%%'/%}" \
      "${_prompt_vcs_defaults[start:right]//'%%'/%}"
  zstyle ':vcs_info:*:prompt_vcs:*' formats \\
      ${(q+):-$_prompt_vcs_defaults[start:chpwd]$_prompt_vcs_defaults[start:left]} \\
      ${(q+)_prompt_vcs_defaults[start:left]} \\
      ${(q+):-%u%c$_prompt_vcs_defaults[start:branch]$_prompt_vcs_defaults[start:repo]}
  zstyle ':vcs_info:*:prompt_vcs:*' actionformats \\
      ${(q+):-$_prompt_vcs_defaults[start:chpwd]$_prompt_vcs_defaults[start:left]} \\
      ${(q+)_prompt_vcs_defaults[start:left]} \\
      ${(q+):-%u%c$_prompt_vcs_defaults[start:action]$_prompt_vcs_defaults[start:repo]}

  # These set the values of %c and %u, respectively:
  zstyle ':vcs_info:*:prompt_vcs:*' stagedstr ${(q+)_prompt_vcs_defaults[start:staged]}
  zstyle ':vcs_info:*:prompt_vcs:*' unstagedstr ${(q+)_prompt_vcs_defaults[start:unstaged]}

For more info on the config above, see
http://zsh.sourceforge.net/Doc/Release/Prompt-Expansion.html and the end of
http://zsh.sourceforge.net/Doc/Release/User-Contributions.html#vcs_005finfo-Configuration"
}

# Sets a style if it hasn't been set yet.
_prompt_vcs_zstyle() {
  local -a val
  zstyle -g val "$1" "$2"
  (( $#val )) ||
      zstyle "$@"
}

_prompt_vcs_info() {
  _prompt_vcs_zstyle ':vcs_info:*:prompt_vcs:*' max-exports 3 # Default is 2.

  _prompt_vcs_zstyle ':vcs_info:*:prompt_vcs:*' nvcsformats \
      "${${:-$_prompt_vcs_defaults[start:chpwd]$_prompt_vcs_defaults[start:left]}//'%%'/%}" \
      "${_prompt_vcs_defaults[start:left]//'%%'/%}" \
      "${_prompt_vcs_defaults[start:right]//'%%'/%}"
  _prompt_vcs_zstyle ':vcs_info:*:prompt_vcs:*' formats \
      "$_prompt_vcs_defaults[start:chpwd]$_prompt_vcs_defaults[start:left]" \
      "$_prompt_vcs_defaults[start:left]" \
      "%u%c$_prompt_vcs_defaults[start:branch]$_prompt_vcs_defaults[start:repo]"
  _prompt_vcs_zstyle ':vcs_info:*:prompt_vcs:*' actionformats \
      "$_prompt_vcs_defaults[start:chpwd]$_prompt_vcs_defaults[start:left]" \
      "$_prompt_vcs_defaults[start:left]" \
      "%u%c$_prompt_vcs_defaults[start:action]$_prompt_vcs_defaults[start:repo]"
  _prompt_vcs_zstyle ':vcs_info:*:prompt_vcs:*' stagedstr \
      "$_prompt_vcs_defaults[start:staged]"
  _prompt_vcs_zstyle ':vcs_info:*:prompt_vcs:*' unstagedstr \
      "$_prompt_vcs_defaults[start:unstaged]"

  vcs_info prompt_vcs # Call with namespace.

  print -rNC1 -- \
      "${(q+)vcs_info_msg_0_}" "${(q+)vcs_info_msg_1_}" "${(q+)vcs_info_msg_2_}"
}

prompt_vcs_chpwd() {
  emulate -L zsh

  local -i fd=-1; local -a reply
  exec {fd}< <(
    # Fetch only staged changes at this point, for performance reasons.
    _prompt_vcs_zstyle ':vcs_info:*:prompt_vcs:*' check-for-staged-changes yes
    _prompt_vcs_info
  )
  IFS=$'\0' read -Aru "$fd"
  typeset -ga _prompt_vcs_info_msg_=( "${(@Q)reply}" )
  exec {fd}<&-

  PS1="$_prompt_vcs_info_msg_[1]"
  RPS1="$_prompt_vcs_info_msg_[3]"
}

prompt_vcs_precmd() {
  local exitstatus=$? # Exit status of last command
  emulate -L zsh

  # Assign human-friendly exit status string to %v.
  psvar[1]=
  case $exitstatus in
    ( <128-> )
      psvar[1]="SIG$signals[exitstatus-127] "
      ;|
    ( <64-78> )
      psvar[1]="EX_$sysexits[exitstatus-63] "
      ;|
    ( <1-> )
      psvar[1]+="($exitstatus)"
      ;;
    # No need to show EX_OK.
  esac
}

prompt_vcs_line-init() {
  emulate -L zsh

  case $CONTEXT in
    start ) # (R)PS1
      # Asynchronously check for unstaged changes. Do this here & not in
      # precmd, so you can press Enter on an empty line to update VCS info.
      local -i fd=-1
      exec {fd}< <(
        _prompt_vcs_zstyle ':vcs_info:*:prompt_vcs:*' check-for-changes yes
        _prompt_vcs_info
        print -r -- "$PWD"
      )

      # Add callback. Needs to be a widget, so we can refresh the prompt.
      zle -Fw "$fd" prompt_vcs_fd-handler
      ;;
    cont )  # (R)PS2
      # Indent left continuation prompt for each open shell construct.
      local fmt="$_prompt_vcs_defaults[cont:indent]"
      local -a indent=( '%('{1..$(( COLUMNS / ${(m)#fmt} ))}"_,$fmt,)" )
      PS2="${(j::)indent}$_prompt_vcs_defaults[cont:left]"

      RPS2="$_prompt_vcs_defaults[cont:right]"
      ;;
  esac
}

# Callback widget function for our async fetch of unstaged VCS changes
prompt_vcs_fd-handler() {
  emulate -L zsh

  local -i fd=$1; local sig=$2; local -a reply
  {
    zle -F "$fd"  # Detach ourselves, so we don't get called more than once.

    [[ $sig != (|hup) ]] &&
        return  # Error occured

    IFS=$'\0' read -Aru "$fd"

    [[ $reply[-1] != $PWD ]] &&
        return  # Abort if the info is not for the current dir.
  } always {
    exec {fd}<&-
  }
  shift -p reply
  typeset -ga _prompt_vcs_info_msg_=( "${(@Q)reply}" )
  RPS1="$_prompt_vcs_info_msg_[3]"
  zle .reset-prompt
}

prompt_vcs_line-finish() {
  emulate -L zsh
  PS1="$_prompt_vcs_info_msg_[2]"
}

prompt_vcs_setup() {
  prompt_opts=( cr percent sp ) # Tell promptinit which options to set.

  PS4=$'# ?=%(?,%F{green},%B%F{red}%S)%?%b%f%s e=%e %F{green}%1N%f:%I %(1_,%F{yellow}%K{black}%_%f%k ,)'
  SPROMPT='Correct %B%F{red}%U%R%b%f%u to %B%F{green}%r%b%f? [%Sy%ses|%Sn%so|%Se%sdit|%Sa%sbort] '
  PROMPT_EOL_MARK='%S%F{cyan}%#%s%f'
  zle_highlight=(
      isearch:fg=black,bg=yellow
      special:fg=cyan,bold
      region:bg=blue
      suffix:bg=blue
      paste:none
  )

  add-zsh-hook chpwd    prompt_vcs_chpwd
  add-zsh-hook precmd   prompt_vcs_precmd
  add-zle-hook-widget line-init   prompt_vcs_line-init
  add-zle-hook-widget line-finish prompt_vcs_line-finish
  zle -N prompt_vcs_fd-handler # Callback widget for async VCS update.

  prompt_vcs_chpwd
}

prompt_vcs_setup "$@"