#!/usr/bin/env bash
# fzf-tmux: starts fzf in a tmux pane
# usage: fzf-tmux [-u|-d [HEIGHT[%]]] [-l|-r [WIDTH[%]]] [--] [FZF OPTIONS]

args=()
opt=""
skip=""
swap=""
close=""
term=""
while [ $# -gt 0 ]; do
  arg="$1"
  case "$arg" in
    -)
      term=1
      ;;
    -w*|-h*|-d*|-u*|-r*|-l*)
      if [ -n "$skip" ]; then
        args+=("$1")
        shift
        continue
      fi
      if [[ "$arg" =~ ^.[lrw] ]]; then
        opt="-h"
        if [[ "$arg" =~ ^.l ]]; then
          opt="$opt -d"
          swap="; swap-pane -D ; select-pane -L"
          close="; tmux swap-pane -D"
        fi
      else
        opt=""
        if [[ "$arg" =~ ^.u ]]; then
          opt="$opt -d"
          swap="; swap-pane -D ; select-pane -U"
          close="; tmux swap-pane -D"
        fi
      fi
      if [ ${#arg} -gt 2 ]; then
        size="${arg:2}"
      else
        shift
        if [[ "$1" =~ ^[0-9]+%?$ ]]; then
          size="$1"
        else
          [ -n "$1" -a "$1" != "--" ] && args+=("$1")
          shift
          continue
        fi
      fi

      if [[ "$size" =~ %$ ]]; then
        size=${size:0:((${#size}-1))}
        if [ -n "$swap" ]; then
          opt="$opt -p $(( 100 - size ))"
        else
          opt="$opt -p $size"
        fi
      else
        if [ -n "$swap" ]; then
          if [[ "$arg" =~ ^.l ]]; then
            [ -n "$COLUMNS" ] && max=$COLUMNS || max=$(tput cols)
          else
            [ -n "$LINES" ] && max=$LINES || max=$(tput lines)
          fi
          size=$(( max - size ))
          [ $size -lt 0 ] && size=0
          opt="$opt -l $size"
        else
          opt="$opt -l $size"
        fi
      fi
      ;;
    --)
      # "--" can be used to separate fzf-tmux options from fzf options to
      # avoid conflicts
      skip=1
      ;;
    *)
      args+=("$1")
      ;;
  esac
  shift
done

if [ -z "$TMUX_PANE" ] || tmux list-panes -F '#F' | grep -q Z; then
  fzf "${args[@]}"
  exit $?
fi

set -e

# Clean up named pipes on exit
id=$RANDOM
argsf=/tmp/fzf-args-$id
fifo1=/tmp/fzf-fifo1-$id
fifo2=/tmp/fzf-fifo2-$id
fifo3=/tmp/fzf-fifo3-$id
cleanup() {
  rm -f $argsf $fifo1 $fifo2 $fifo3
}
trap cleanup EXIT SIGINT SIGTERM

fail() {
  >&2 echo "$1"
  exit 1
}
fzf="$(which fzf 2> /dev/null)" || fzf="$(dirname "$0")/fzf"
[ -x "$fzf" ] || fail "fzf executable not found"

envs="env "
[ -n "$FZF_DEFAULT_OPTS"    ] && envs="$envs FZF_DEFAULT_OPTS=$(printf %q "$FZF_DEFAULT_OPTS")"
[ -n "$FZF_DEFAULT_COMMAND" ] && envs="$envs FZF_DEFAULT_COMMAND=$(printf %q "$FZF_DEFAULT_COMMAND")"

mkfifo $fifo2
mkfifo $fifo3

# Build arguments to fzf
opts=""
for arg in "${args[@]}"; do
  opts="$opts \"${arg//\"/\\\"}\""
done

if [ -n "$term" -o -t 0 ]; then
  cat <<< "$fzf $opts > $fifo2; echo \$? > $fifo3 $close" > $argsf
  tmux set-window-option -q synchronize-panes off \;\
    split-window $opt "cd $(printf %q "$PWD");$envs bash $argsf" $swap
else
  mkfifo $fifo1
  cat <<< "$fzf $opts < $fifo1 > $fifo2; echo \$? > $fifo3 $close" > $argsf
  tmux set-window-option -q synchronize-panes off \;\
    split-window $opt "$envs bash $argsf" $swap
  cat <&0 > $fifo1 &
fi
cat $fifo2
[ "$(cat $fifo3)" = '0' ]