#!/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=""
while [ $# -gt 0 ]; do
  arg="$1"
  case "$arg" in
    -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
          [[ "$arg" =~ ^.l ]] && max=$(tput cols) || max=$(tput lines)
          size=$(( 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 "$TMUX_PANE" ]; then
  fzf "${args[@]}"
  exit $?
fi

set -e

# Build arguments to fzf
[ ${#args[@]} -gt 0 ] && fzf_args=$(printf '\\"%s\\" ' "${args[@]}"; echo '')

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

fail() {
  >&2 echo "$1"
  exit 1
}
fzf=$(which fzf 2> /dev/null) || fail "fzf executable not found"
envs="FZF_DEFAULT_OPTS=$(printf %q "$FZF_DEFAULT_OPTS") FZF_DEFAULT_COMMAND=$(printf %q "$FZF_DEFAULT_COMMAND")"

mkfifo $fifo2
mkfifo $fifo3
if [ -t 0 ]; then
  tmux set-window-option -q synchronize-panes off \;\
    split-window $opt "$envs"' sh -c "'$fzf' '"$fzf_args"' > '$fifo2'; echo \$? > '$fifo3' '"$close"'"' $swap
else
  mkfifo $fifo1
  tmux set-window-option -q synchronize-panes off \;\
    split-window $opt "$envs"' sh -c "'$fzf' '"$fzf_args"' < '$fifo1' > '$fifo2'; echo \$? > '$fifo3' '"$close"'"' $swap
  cat <&0 > $fifo1 &
fi
cat $fifo2
[ "$(cat $fifo3)" = '0' ]