#!/usr/bin/env bash
set -euo pipefail

I3_MSG='/usr/bin/i3-msg'

quote_i3_string() {
  local value="$1"
  value=${value//\\/\\\\}
  value=${value//\"/\\\"}
  printf '%s' "$value"
}

focused_workspace() {
  "$I3_MSG" -t get_workspaces | jq -r '.[] | select(.focused) | .name'
}

bpm_info() {
  "$I3_MSG" -t get_tree | jq -r '
    def walk($ws):
      (if .type == "workspace" then .name else $ws end) as $current_ws
      | if (.window != null)
          and ((.window_properties.class // "") == "steam")
          and ((.window_properties.instance // "") == "steamwebhelper")
          and ((.name // "") | test("Big Picture|大屏幕模式"))
        then "\(.id)\t\($current_ws)"
        else empty
        end,
        (.nodes[]? | walk($current_ws)),
        (.floating_nodes[]? | walk($current_ws));
    walk(null)
  ' | head -n1
}

candidate_window() {
  jq -e '
    (.container.window != null)
    and (((.container.window_properties.class // "") | ascii_downcase) != "steam")
    and (((.container.name // "") | test("Big Picture|大屏幕模式")) | not)
    and (
      (.container.window_type // "normal") as $window_type
      | ($window_type == "normal" or $window_type == "dialog" or $window_type == "utility")
    )
  ' >/dev/null
}

focus_game() {
  local container_id="$1"
  local workspace_name="$2"
  local bpm_id="$3"
  local escaped_workspace

  escaped_workspace="$(quote_i3_string "$workspace_name")"

  "$I3_MSG" \
    "[con_id=${bpm_id}] fullscreen disable; [con_id=${container_id}] move container to workspace \"${escaped_workspace}\"; workspace \"${escaped_workspace}\"; [con_id=${container_id}] focus; [con_id=${container_id}] fullscreen enable" \
    >/dev/null
}

restore_bpm() {
  local bpm_id="$1"
  local workspace_name="$2"
  local escaped_workspace

  escaped_workspace="$(quote_i3_string "$workspace_name")"

  "$I3_MSG" \
    "workspace \"${escaped_workspace}\"; [con_id=${bpm_id}] focus; [con_id=${bpm_id}] fullscreen enable" \
    >/dev/null
}

active_game_id=''

"$I3_MSG" -m -t subscribe '[ "window" ]' | while IFS= read -r event; do
  [[ -n "$event" ]] || continue

  change="$(jq -r '.change // empty' <<<"$event")"
  [[ -n "$change" ]] || continue

  bpm="$(bpm_info)"
  bpm_id="${bpm%%$'\t'*}"
  bpm_workspace="${bpm#*$'\t'}"

  case "$change" in
    new)
      [[ -n "$bpm" ]] || continue
      [[ "$(focused_workspace)" == "$bpm_workspace" ]] || continue
      candidate_window <<<"$event" || continue

      container_id="$(jq -r '.container.id' <<<"$event")"
      focus_game "$container_id" "$bpm_workspace" "$bpm_id" || true
      active_game_id="$container_id"
      ;;
    close)
      container_id="$(jq -r '.container.id // empty' <<<"$event")"
      [[ -n "$active_game_id" ]] || continue
      [[ "$container_id" == "$active_game_id" ]] || continue

      active_game_id=''
      [[ -n "$bpm" ]] || continue

      sleep 0.15
      restore_bpm "$bpm_id" "$bpm_workspace" || true
      ;;
  esac
done