#!/usr/bin/env bash
# Cadence — install deps (if needed) and start the dashboard on http://localhost:8000
#
#   bash run.sh              → port 8000
#   PORT=8010 bash run.sh    → custom port
#
# If the browser says "not answering on 127.0.0.1:8000", this script tells you why
# instead of exiting quietly.
set -uo pipefail
cd "$(dirname "$0")"

PORT="${PORT:-8000}"

bold() { printf '\033[1m%s\033[0m\n' "$*"; }
ok()   { printf '  \033[32m✓\033[0m %s\n' "$*"; }
bad()  { printf '  \033[31m✗\033[0m %s\n' "$*"; }
warn() { printf '  \033[33m!\033[0m %s\n' "$*"; }

die() { bad "$1"; shift; for line in "$@"; do echo "    $line"; done; exit 1; }

# ── 1. python itself ─────────────────────────────────────────────────────────
if ! command -v python3 >/dev/null 2>&1; then
  die "python3 is not installed." \
      "macOS:  brew install python   (or install from python.org)" \
      "Debian/Ubuntu:  sudo apt install python3 python3-venv python3-pip"
fi

PYV="$(python3 -c 'import sys;print("%d.%d"%sys.version_info[:2])' 2>/dev/null || echo "?")"
case "$PYV" in
  3.9|3.1[0-9]|3.[2-9][0-9]|[4-9].*) ok "python $PYV" ;;
  *) die "python $PYV is too old — Cadence needs 3.9 or newer." \
         "Install a newer python3, then run: bash run.sh" ;;
esac

# ── 2. is the port already taken? ────────────────────────────────────────────
port_busy() {
  if command -v ss >/dev/null 2>&1; then ss -ltn 2>/dev/null | grep -q ":${PORT} "; return $?; fi
  if command -v lsof >/dev/null 2>&1; then lsof -iTCP:"${PORT}" -sTCP:LISTEN >/dev/null 2>&1; return $?; fi
  return 1
}
if port_busy; then
  # A Cadence backend already listening is fine — say so, don't start a second one.
  if curl -fsS -m 3 "http://127.0.0.1:${PORT}/healthz" >/dev/null 2>&1; then
    ok "Cadence is already running on http://localhost:${PORT}"
    echo
    echo "  Open http://localhost:${PORT} — nothing else to do."
    echo "  (Stop the old one first if you want a restart.)"
    exit 0
  fi
  die "port ${PORT} is already used by another program." \
      "Start Cadence on a different port:  PORT=8010 bash run.sh" \
      "See what holds it:  lsof -iTCP:${PORT} -sTCP:LISTEN   (or: ss -ltnp | grep ${PORT})"
fi

# ── 3. dependencies ──────────────────────────────────────────────────────────
have_deps() { "$1" -c 'import flask, yt_dlp, ytmusicapi, requests' >/dev/null 2>&1; }

PY=python3
if have_deps python3; then
  ok "dependencies already available"
else
  bold "Installing dependencies (first run only)"
  if python3 -m pip install -q -r requirements.txt >/dev/null 2>&1 && have_deps python3; then
    ok "installed into system python"
  else
    # PEP 668 "externally managed" systems (Debian, Ubuntu, Homebrew) refuse system pip
    warn "system pip declined — using a local virtualenv in ./.venv"
    if [ ! -d .venv ]; then
      python3 -m venv .venv >/dev/null 2>&1 || die "could not create .venv" \
          "Debian/Ubuntu:  sudo apt install python3-venv   then re-run: bash run.sh" \
          "macOS:  brew install python   then re-run: bash run.sh"
    fi
    ./.venv/bin/pip install -q -r requirements.txt || die "pip install failed" \
        "Check your internet connection, then re-run: bash run.sh" \
        "Behind a proxy?  export HTTPS_PROXY=http://host:port"
    have_deps ./.venv/bin/python || die "dependencies still missing after install" \
        "Try: rm -rf .venv && bash run.sh"
    ok "installed into ./.venv"
    PY=./.venv/bin/python
  fi
fi

# ── 4. start ─────────────────────────────────────────────────────────────────
bold "Starting Cadence on http://localhost:${PORT}"
echo "  (Ctrl+C stops it)"
echo
PORT="$PORT" exec "$PY" app.py