#!/usr/bin/env zsh

# http://zsh.sourceforge.net/Doc/Release/Zsh-Line-Editor.html
# http://zsh.sourceforge.net/Doc/Release/Zsh-Line-Editor.html#Zle-Builtins
# http://zsh.sourceforge.net/Doc/Release/Zsh-Line-Editor.html#Standard-Widgets

# _fzf_history_widget {{{
  # taken from https://github.com/junegunn/fzf/blob/master/shell/key-bindings.zsh
  _fzf_history_widget() {
    setopt local_options pipe_fail
    local selected
    selected=(
      $(fc -rl 1 |
        fzf --height=40% --reverse --nth=2.. --tiebreak=index --query="$LBUFFER")
    )
    local fzf_ret="$?"
    if (( ${#selected} )); then
      zle vi-fetch-history -n "${selected[1]}"
    fi
    zle reset-prompt
    return "$fzf_ret"
  }

  zle -N _fzf_history_widget
  bindkey '\er' _fzf_history_widget
# }}}

# palette {{{
  # This widget lets you select a command snippet and fill in its placeholders.
  # It uses "TLDR pages" as the snippet database, so the widget will download
  # them on the first invocation.  Or, you can also create a symlink to a local
  # cache of a "TLDR pages" client, e.g. for tealdeer (which is what I use):
  #
  #   ln -sv ~/.cache/tealdeer/tldr-master/pages $ZSH_CACHE_DIR/tldr-pages
  #
  # Usage:
  # 1. press Alt+Shift+P (or Esc+Shift+P)
  # 2. select snippet in the fuzzy finder (fzf)
  # 3. Press Alt+Shift+P again, this time it'll take you to the first placeholder
  # 4. Enter some text
  # 5. Repeat steps 3 and 4 until there're no placeholders left
  #
  # Requirements/Dependencies:
  # 1. AWK (any implementation will probably work) for parsing "TLDR pages"
  # 2. the FZF fuzzy finder
  # 3. Tar (any implementation will probably work) and Curl for downloading
  #    "TLDR pages"

  PALETTE_TLDR_PAGES_DIR="$ZSH_CACHE_DIR/tldr-pages"

  # strings which are used to mark placeholders (please don't modify)
  PALETTE_PLACEHOLDER_START="{{"
  PALETTE_PLACEHOLDER_END="}}"

  # a string which is used to separate snippet from its description in the
  # fuzzy-finder
  PALETTE_SNIPPET_COMMENT="    ## "

  # Main function of the widget
  _palette_widget() {
    # download "TLDR pages" if we don't have them
    if [[ ! -d "$PALETTE_TLDR_PAGES_DIR" ]]; then
      print -r
      _palette_download_tldr_pages
      print -r
    fi

    # try to fill in a placeholder if there're any, otherwise pick a snippet
    if ! _palette_fill_in_placeholder; then
      local selected
      if selected="$(_palette_parse_tldr_pages | fzf --height 40% --reverse --ansi)"
      then
        # paste selected snippet without its description
        zle -U "${selected%%$PALETTE_SNIPPET_COMMENT*}"
      fi
    fi

    # immediately redraw
    zle redisplay
  }

  # This function deletes the first placeholder from the buffer and places the
  # cursor at the beginning of that placeholder. If there're no placeholders in
  # the buffer, it exits with exit code 1.
  _palette_fill_in_placeholder() {
    # NOTE!!! indexes in ZSH arrays start at one!
    local start_index="${BUFFER[(i)$PALETTE_PLACEHOLDER_START]}"
    (( start_index == 0 || start_index > ${#BUFFER} )) && return 1
    local end_index="${BUFFER[(i)$PALETTE_PLACEHOLDER_END]}"
    # the CURSOR variable is zero-based while ZSH arrays are one-based
    (( CURSOR = start_index - 1 ))
    BUFFER="${BUFFER[1,start_index-1]}${BUFFER[end_index+2,${#BUFFER}]}"
  }

  # This function parses "TLDR pages" for snippets using AWK. Fortunately, all
  # "TLDR pages" files are use the same Markdown-like syntax so they're very easy
  # to parse.
  _palette_parse_tldr_pages() {
    # I chose to use AWK here because it was designed specifically for text
    # processing and includes all basic utilities that I need here.
    awk '
      # when we find a "description" line...
      match($0, /^- (.+):$/, match_groups) {
        # ...get actual description from it...
        description = match_groups[1]
        # ...then skip any lines that are not actual commands, while saving RegEx
        # match groups...
        while (!match($0, /^`(.+)`$/, match_groups)) getline
        # ...after that we can get the command...
        command = match_groups[1]
        # ...and finally, we print command and description, separated by
        # PALETTE_SNIPPET_COMMENT, and with some colors!
        printf "%s\x1b[90m'"$PALETTE_SNIPPET_COMMENT"'%s\x1b[0m\n", command, description
      }
    ' "$PALETTE_TLDR_PAGES_DIR"/**/*.md
  }

  # This function downloads the "TLDR pages"
  _palette_download_tldr_pages() {
    mkdir -pv "$PALETTE_TLDR_PAGES_DIR"
    print -r -- "Downloading tldr pages..."

    if curl -Lf https://github.com/tldr-pages/tldr/archive/master.tar.gz |
      tar -C "$PALETTE_TLDR_PAGES_DIR" --gzip --strip-components 2 --extract tldr-master/pages
    then
      print -r -- "Done!"
    fi
  }

  # finally, bind the widget to Alt+Shift+P (or Esc+Shift+P)
  zle -N _palette_widget
  bindkey '\eP' _palette_widget
# }}}

# expand-or-complete-with-dots {{{
  # expand-or-complete-with-dots() {
  #   local wrap_ctrl_supported
  #   if (( ${+terminfo[rmam]} && ${+terminfo[smam]} )); then
  #     wrap_ctrl_supported=1
  #   fi
  #   # toggle line-wrapping off and back on again
  #   if [[ -n "$wrap_ctrl_supported" ]]; then echoti rmam; fi
  #   print -Pn "%F{red}...%f"
  #   if [[ -n "$wrap_ctrl_supported" ]]; then echoti smam; fi
  #   zle expand-or-complete
  #   zle redisplay
  # }
  # zle -N expand-or-complete-with-dots
  # bindkey "^I" expand-or-complete-with-dots
# }}}

# find man page widget {{{
  _widget_find_man_page() {
    local words=("${(@z)BUFFER}")
    local cmd_name="${words[1]}"
    zle push-line
    local manpage=""
    manpage="$(fzf-search-manpage "$cmd_name")"
    BUFFER="man $manpage"
    zle accept-line
  }
  zle -N find-man-page _widget_find_man_page
  # bind to F1
  bindkey '\eOP' find-man-page
# }}}

# other keybindings {{{

  bindkey '\ee' edit-command-line

# }}}