#!/usr/bin/env bash
CURRENT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$CURRENT_DIR/helpers.sh"

declare S=$'\t'

# === common
get_current_session_name() {
  if [ "$(tmux display-message -p "#{session_grouped}")" = 0 ]; then
    tmux display-message -p "#{session_name}" 2>/dev/null || true
  else
    tmux display-message -p "#{session_group}" 2>/dev/null || true
  fi
}

rename_session() {
  local old="$1"
  local new="$2"
  local dir="$(get_opt_dir)"

  [[ -z "$new" || "$old" == "$new" ]] && return 1
  [[ -e "${dir}/${new}_last" ]] && return 1

  tmux has-session -t "$new" 2>/dev/null && return 1
  tmux rename-session -t "$old" "$new" 2>/dev/null

  local old_last="${dir}/${old}_last"
  [[ -L "$old_last" ]] && {
    local actual="$(readlink "$old_last")"
    local new_actual="${dir}/${new}_$(basename "$actual" | cut -d_ -f2-)"
    mv "$actual" "$new_actual"
    ln -sf "$new_actual" "${dir}/${new}_last"
    rm "$old_last"
  }
}

# === save
save_cwd() {
  local session_name="$1"
  local save_file="$2"
  tmux display-message -p -t "$session_name" -F "#{session_path}" >>"$save_file"
}

save_windows() {
  local session_name="$1"
  local save_file="$2"
  local format="window$S#{window_index}$S#{window_name}$S#{window_layout}$S#{window_active}"
  tmux list-windows -t "$session_name" -F "$format" >>"$save_file"

}

save_panes() {
  local session_name="$1"
  local save_file="$2"
  local format="pane$S#{pane_index}$S#{pane_current_path}$S#{pane_active}$S#{window_index}$S#{pane_pid}"
  tmux list-panes -s -t "$session_name" -F "$format" |
    while IFS="$S" read -r line; do
      pids=$(ps -ao "ppid,pid" |
        sed "s/^ *//" |
        grep "^$(cut -f6 <<<"$line")" |
        rev |
        cut -d' ' -f1 |
        rev)

      command="$(
        for pid in $pids; do
          while read -r arg; do
            echo -n "'$arg' "
          done <<<"$(xargs -0L1 </proc/"$pid"/cmdline 2>/dev/null)"
        done
      )"

      awk -v command="$command" \
        'BEGIN {FS=OFS="\t"} {$6=command; print}' \
        <<<"$line" >>"$save_file"
    done
}

link_session_last() {
  local save_file="$1"
  local last_file="$2"
  if ! cmp -s "$save_file" "$last_file"; then
    ln -sf "$save_file" "$last_file"
  else
    rm "$save_file"
  fi
}

link_last() {
  local save_file="$1"
  local save_dir="$2"
  ln -sf "$save_file" "$save_dir"/last
}

save_session() {
  local session_name="$1"
  local save_dir="$(get_opt_dir)"
  local save_file="${save_dir}/${session_name}_$(get_time)"
  local last_file="${save_dir}/${session_name}_last"

  save_cwd "$session_name" "$save_file"
  save_windows "$session_name" "$save_file"
  save_panes "$session_name" "$save_file"
  link_session_last "$save_file" "$last_file"
  link_last "$last_file" "$save_dir"
}

save_all_sessions() {
  tmux list-sessions -F "#{session_name}" | while read -r session; do
    save_session "$session"
  done

  local current_session="$(get_current_session_name)"
  if [[ -n "$current_session" ]]; then
    link_last "$(get_opt_dir)/${current_session}_last" "$(get_opt_dir)"
  fi
}

unload_session() {
  local session_name="$1"
  save_session "$session_name"
  tmux kill-session -t "$session_name"
}

# === restore
restore_session_from_file() {
  local session_file="$1"
  local session_name=$(basename "$session_file" | sed 's/_last$//')
  exec <"$session_file"

  start_spinner "Restoring session $session_name"

  local session_path="$(head -n1 | cut -d"$SEPARATOR" -f2)"
  tmux new-session -ds "$session_name" -c "$session_path"

  declare -A window_layouts
  declare active_window
  while read -r line; do
    case $line in
    window*)
      IFS=$S read -r _ window_index window_name window_layout window_active <<<"$line"
      window_id="$session_name:$window_index"
      tmux new-window -k -t "$window_id" -n "$window_name"
      window_layouts["$window_id"]="$window_layout"
      if [[ "$window_active" == "1" ]]; then
        active_window="$window_id"
      fi
      ;;

    pane*)
      IFS=$S read -r _ pane_index pane_current_path pane_active window_index command <<<"$line"
      if [[ "$pane_index" == "$(get_tmux_option base-index 0)" ]]; then
        tmux send-keys -t "$session_name:$window_index" "cd \"$pane_current_path\"" Enter "clear" Enter
      else
        tmux split-window -d -t "$session_name:$window_index" -c "$pane_current_path"
      fi
      if [[ "$pane_active" == "1" ]]; then
        tmux select-pane -t "$session_name:$window_index.$pane_index"
      fi
      if [[ -n "$command" ]]; then
        tmux send-keys -t "$session_name:$window_index.$pane_index" "$command" Enter
      fi
      ;;
    esac
  done

  for window in "${!window_layouts[@]}"; do
    tmux select-layout -t "$window" "${window_layouts[$window]}"
  done

  tmux select-window -t "$active_window"
  tmux switch-client -t "$session_name"
  stop_spinner "Session restored"
}

restore_session() {
  local session_name="$1"
  if tmux has-session -t "$session_name" 2>/dev/null; then
    tmux switch-client -t "$session_name"
    return 0
  fi

  local session_file="$(get_opt_dir)/${session_name}_last"
  if [[ ! -f "$session_file" ]]; then
    tmux display-message "No saved session found for: $session_name"
    return 1
  fi

  restore_session_from_file "$session_file"
}

restore_last() {
  local last_file="$(get_opt_dir)/last"
  if [[ ! -e "$last_file" ]]; then
    tmux display-message "No last session saved"
    return 1
  fi

  local session_name=$(basename "$(readlink "$last_file")" | sed 's/_last$//')
  restore_session "$session_name"
}