#!/bin/bash

set -euo pipefail

# pw-throttle.sh — apply CPU + network throttling to a playwright-cli Chromium
# session so UI can be verified as it behaves on low-spec devices / slow networks.
#
# @playwright/cli has no throttle command, so this wraps a CDP call via `run-code`.
# The throttle is set on the page target and persists for the life of the session:
# apply it once, then run the usual playwright-cli goto/snapshot/screenshot commands
# on the same -s=<session>. CDP is Chromium-only, so this works on chrome/msedge
# sessions but not firefox/webkit.

usage() {
  echo "Usage: ./scripts/pw-throttle.sh <session> <profile>"
  echo "  profiles:"
  echo "    mid   4x CPU + ~1.6 Mbps / 750 Kbps / 150ms   (mid-tier phone, Lighthouse mobile default)"
  echo "    low   6x CPU + ~400 Kbps / 400 Kbps / 400ms   (low-end phone / poor connection)"
  echo "    cpu4  4x CPU, full-speed network              (isolate JS cost)"
  echo "    cpu6  6x CPU, full-speed network              (isolate JS cost)"
  echo "    off   reset to full speed"
}

if [ "$#" -lt 2 ]; then
  usage >&2
  exit 1
fi

session="$1"
profile="$2"

# downloadThroughput / uploadThroughput are bytes/sec; latency is ms.
# A value <= 0 for throughput/latency disables that part of network throttling.
case "$profile" in
  mid)  cpu=4; down=200000; up=93750; lat=150 ;;
  low)  cpu=6; down=50000;  up=50000; lat=400 ;;
  cpu4) cpu=4; down=-1;     up=-1;    lat=0 ;;
  cpu6) cpu=6; down=-1;     up=-1;    lat=0 ;;
  off)  cpu=1; down=-1;     up=-1;    lat=0 ;;
  *) echo "pw-throttle: unknown profile '$profile'" >&2; usage >&2; exit 1 ;;
esac

echo "pw-throttle: applying '$profile' to session '$session' (cpu ${cpu}x, down ${down} B/s, up ${up} B/s, latency ${lat} ms; Chromium only)"

playwright-cli -s="$session" run-code "async page => {
  const client = await page.context().newCDPSession(page);
  await client.send('Network.enable');
  await client.send('Emulation.setCPUThrottlingRate', { rate: $cpu });
  await client.send('Network.emulateNetworkConditions', { offline: false, downloadThroughput: $down, uploadThroughput: $up, latency: $lat });
}"