#!/usr/bin/env zsh
# -------------------------------------------------------------------------------------------------
# Copyright (c) 2010-2011 zsh-syntax-highlighting contributors
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification, are permitted
# provided that the following conditions are met:
#
#  * Redistributions of source code must retain the above copyright notice, this list of conditions
#    and the following disclaimer.
#  * Redistributions in binary form must reproduce the above copyright notice, this list of
#    conditions and the following disclaimer in the documentation and/or other materials provided
#    with the distribution.
#  * Neither the name of the zsh-syntax-highlighting contributors nor the names of its contributors
#    may be used to endorse or promote products derived from this software without specific prior
#    written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
# FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
# -------------------------------------------------------------------------------------------------
# -*- mode: zsh; sh-indentation: 2; indent-tabs-mode: nil; sh-basic-offset: 2; -*-
# vim: ft=zsh sw=2 ts=2 et
# -------------------------------------------------------------------------------------------------


# -------------------------------------------------------------------------------------------------
# Core highlighting update system
# -------------------------------------------------------------------------------------------------

# Array declaring active highlighters names.
typeset -ga ZSH_HIGHLIGHT_HIGHLIGHTERS

# Update ZLE buffer syntax highlighting.
#
# Invokes each highlighter that needs updating.
# This function is supposed to be called whenever the ZLE state changes.
_zsh_highlight()
{
  setopt localoptions nowarncreateglobal

  # Store the previous command return code to restore it whatever happens.
  local ret=$?

  # Do not highlight if there are more than 300 chars in the buffer. It's most
  # likely a pasted command or a huge list of files in that case..
  [[ -n $ZSH_HIGHLIGHT_MAXLENGTH ]] && [[ $#BUFFER -gt $ZSH_HIGHLIGHT_MAXLENGTH ]] && return $ret

  # Do not highlight if there are pending inputs (copy/paste).
  [[ $PENDING -gt 0 ]] && return $ret

  {
    local -a selected_highlighters
    local cache_place

    # Select which highlighters in ZSH_HIGHLIGHT_HIGHLIGHTERS need to be invoked.
    local highlighter; for highlighter in $ZSH_HIGHLIGHT_HIGHLIGHTERS; do

      # If highlighter needs to be invoked
      if "_zsh_highlight_${highlighter}_highlighter_predicate"; then

        # Mark the highlighter as selected for update.
        selected_highlighters+=($highlighter)

        # Remove what was stored in its cache from region_highlight.
        cache_place="_zsh_highlight_${highlighter}_highlighter_cache"
        [[ ${#${(P)cache_place}} -gt 0 ]] && region_highlight=(${region_highlight:#(${(P~j.|.)cache_place})})

      fi
    done

    # Invoke each selected highlighter and store the result in its cache.
    local -a region_highlight_copy
    for highlighter in $selected_highlighters; do
      cache_place="_zsh_highlight_${highlighter}_highlighter_cache"
      region_highlight_copy=($region_highlight)
      {
        "_zsh_highlight_${highlighter}_highlighter"
      } always  {
        : ${(PA)cache_place::=${region_highlight:#(${(~j.|.)region_highlight_copy})}}
      }
    done

  } always {
    _ZSH_HIGHLIGHT_PRIOR_BUFFER=$BUFFER
    _ZSH_HIGHLIGHT_PRIOR_CURSOR=$CURSOR
    return $ret
  }
}


# -------------------------------------------------------------------------------------------------
# API/utility functions for highlighters
# -------------------------------------------------------------------------------------------------

# Array used by highlighters to declare user overridable styles.
typeset -gA ZSH_HIGHLIGHT_STYLES

# Whether the command line buffer has been modified or not.
#
# Returns 0 if the buffer has changed since _zsh_highlight was last called.
_zsh_highlight_buffer_modified()
{
  [[ ${_ZSH_HIGHLIGHT_PRIOR_BUFFER:-} != $BUFFER ]]
}

# Whether the cursor has moved or not.
#
# Returns 0 if the cursor has moved since _zsh_highlight was last called.
_zsh_highlight_cursor_moved()
{
  [[ -n $CURSOR ]] && [[ -n $_ZSH_HIGHLIGHT_PRIOR_CURSOR ]] && (($_ZSH_HIGHLIGHT_PRIOR_CURSOR != $CURSOR))
}


# -------------------------------------------------------------------------------------------------
# Setup functions
# -------------------------------------------------------------------------------------------------

# Rebind all ZLE widgets to make them invoke _zsh_highlights.
_zsh_highlight_bind_widgets()
{
  # Load ZSH module zsh/zleparameter, needed to override user defined widgets.
  zmodload zsh/zleparameter 2>/dev/null || {
    echo 'zsh-syntax-highlighting: failed loading zsh/zleparameter.' >&2
    return 1
  }

  # Override ZLE widgets to make them invoke _zsh_highlight.
  local cur_widget
  for cur_widget in ${${(f)"$(builtin zle -la)"}:#(.*|orig-*|run-help|which-command|beep)}; do
    case $widgets[$cur_widget] in

      # Already rebound event: do nothing.
      user:$cur_widget);;

      # User defined widget: override and rebind old one with prefix "orig-".
      user:*) eval "zle -N orig-$cur_widget ${widgets[$cur_widget]#*:}; \
                    _zsh_highlight_widget_$cur_widget() { builtin zle orig-$cur_widget && _zsh_highlight }; \
                    zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;

      # Completion widget: override and rebind old one with prefix "orig-".
      completion:*) eval "zle -C orig-$cur_widget ${${widgets[$cur_widget]#*:}/:/ }; \
                          _zsh_highlight_widget_$cur_widget() { builtin zle orig-$cur_widget && _zsh_highlight }; \
                          zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;

      # Builtin widget: override and make it call the builtin ".widget".
      builtin) eval "_zsh_highlight_widget_$cur_widget() { builtin zle .$cur_widget && _zsh_highlight }; \
                     zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;

      # Default: unhandled case.
      *) echo "zsh-syntax-highlighting: unhandled ZLE widget '$cur_widget'" >&2 ;;
    esac
  done
}

# Load highlighters from directory.
#
# Arguments:
#   1) Path to the highlighters directory.
_zsh_highlight_load_highlighters()
{
  # Check the directory exists.
  [[ -d "$1" ]] || {
    echo "zsh-syntax-highlighting: highlighters directory '$1' not found." >&2
    return 1
  }

  # Load highlighters from highlighters directory and check they define required functions.
  local highlighter highlighter_dir
  for highlighter_dir ($1/*/); do
    highlighter="${highlighter_dir:t}"
    [[ -f "$highlighter_dir/${highlighter}-highlighter.zsh" ]] && {
      . "$highlighter_dir/${highlighter}-highlighter.zsh"
      type "_zsh_highlight_${highlighter}_highlighter" &> /dev/null &&
      type "_zsh_highlight_${highlighter}_highlighter_predicate" &> /dev/null || {
        echo "zsh-syntax-highlighting: '${highlighter}' highlighter should define both required functions '_zsh_highlight_${highlighter}_highlighter' and '_zsh_highlight_${highlighter}_highlighter_predicate' in '${highlighter_dir}/${highlighter}-highlighter.zsh'." >&2
      }
    }
  done
}


# -------------------------------------------------------------------------------------------------
# Setup
# -------------------------------------------------------------------------------------------------

# Try binding widgets.
_zsh_highlight_bind_widgets || {
  echo 'zsh-syntax-highlighting: failed binding ZLE widgets, exiting.' >&2
  return 1
}

# Resolve highlighters directory location.
_zsh_highlight_load_highlighters "${ZSH_HIGHLIGHT_HIGHLIGHTERS_DIR:-${0:h}/highlighters}" || {
  echo 'zsh-syntax-highlighting: failed loading highlighters, exiting.' >&2
  return 1
}

# Initialize the array of active highlighters if needed.
[[ $#ZSH_HIGHLIGHT_HIGHLIGHTERS -eq 0 ]] && ZSH_HIGHLIGHT_HIGHLIGHTERS=(main)