#!/usr/bin/env bash
# ==============================================================================
# meshinit_eth_bridge.sh — Initialize an 802.11s mesh and **bridge eth2** into it
# ==============================================================================
# PURPOSE
#   This script brings up an IEEE 802.11s mesh interface and bridges it with
#   Ethernet port `eth2` so that any device connected to `eth2` becomes part of
#   the same L2 broadcast domain carried over the mesh. In other words, frames
#   from the Ethernet device are transparently forwarded through the wireless
#   mesh and vice versa.
#
# WHAT'S SPECIAL HERE
#   • We **reuse your existing helper scripts** (freq.sh, node_addresses.sh,
#     topology.sh) — no duplicate frequency maps, no new inventories.  ✅
#   • We keep the script **idempotent**: safe to re-run; it cleans previous
#     state and recreates the intended final configuration.
#   • We provide **extensive in-place comments** explaining every step.
#
# PARAMETERS (positional)
#   1) participating_nodes   Comma-separated list of hostnames (short) or 'all'
#   2) channel               Numeric Wi‑Fi channel (e.g., 36, 44, 149)
#   3) power_dbm             Transmit power in dBm (e.g., 17)
#   4) noise_floor_dbm       Desired NF override (driver-dependent; e.g., -95)
#
# EXAMPLES
#   sudo ./meshinit_eth_bridge.sh all 36 17 -95
#   sudo ./meshinit_eth_bridge.sh apu00,apu01,apu02 44 15 -96
#
# OPTIONAL ENVIRONMENT OVERRIDES
#   MESH_ID="stratumesh"     # 802.11s mesh ID to join
#   BASE_IF="wlan0"          # Underlying Wi‑Fi interface used to spawn mesh0
#   MESH_IF="mesh0"          # Name for the mesh interface (created as type mp)
#   PHY=""                   # Force a specific phy (e.g., phy0). If empty, auto
#   HT_MODE="HT40+"           # Channel width; '+', '-' or omit for 20 MHz
#   COUNTRY="DE"              # Regulatory domain
#   BR_NAME="br-mesh"         # Bridge name that will enslave {mesh_if, eth2}
#   BR_MESH_ADDR=             # Optional IP assigned to the bridge (e.g., 192.168.50.2)
#   BR_MESH_PREFIX=           # Optional CIDR prefix for BR_MESH_ADDR (e.g., 24)
#
# RUNTIME DEPENDENCIES
#   • iproute2 (ip, bridge)   • iw   • awk   • bash ≥ 4 (assoc arrays in helpers)
#   (ethtool/iwpriv not strictly needed; we use debugfs for ath9k NF if available)
#
# EXIT BEHAVIOR
#   • If current host is not in `participating_nodes`, we exit **successfully**
#     with a no-op (useful when running the same command across many nodes).
#
# ------------------------------------------------------------------------------
set -euo pipefail

# ---------- Pretty logging helpers ----------
log()  { echo "[INFO] $*"; }
warn() { echo "[WARN] $*" >&2; }
err()  { echo "[ERROR] $*" >&2; exit 1; }

# ---------- Parse CLI arguments ----------
if [[ ${1:-} == "-h" || ${1:-} == "--help" || $# -lt 4 ]]; then
  cat <<'USAGE'
Usage: meshinit_eth_bridge.sh <participating_nodes|all> <channel> <power_dbm> <noise_floor_dbm>

Examples:
  meshinit_eth_bridge.sh all 36 17 -95
  meshinit_eth_bridge.sh apu00,apu01,apu02 44 15 -96

Environment overrides:
  MESH_ID, BASE_IF, MESH_IF, PHY, HT_MODE, COUNTRY, BR_NAME, BR_MESH_ADDR, BR_MESH_PREFIX
USAGE
  exit 1
fi

PARTICIPATING=$1           # comma-separated list or 'all'
CHAN=$2                     # numeric channel (we map to freq via freq.sh)
POWER_DBM=$3                # desired transmit power in dBm
NOISE_FLOOR=$4              # desired noise floor override in dBm (ath9k best-effort)

HOST_SHORT=$(hostname -s || hostname)

# ---------- Gate: only run on participating nodes ----------
if [[ "$PARTICIPATING" != "all" ]]; then
  IFS=',' read -r -a ALLOWED <<<"$PARTICIPATING"
  IN_SET="no"
  for n in "${ALLOWED[@]}"; do
    [[ "$n" == "$HOST_SHORT" ]] && IN_SET="yes" && break
  done
  if [[ "$IN_SET" != "yes" ]]; then
    log "Host $HOST_SHORT not in participating set; exiting (no-op)."
    exit 0
  fi
fi

# ---------- Privilege check ----------
[[ $EUID -eq 0 ]] || err "Please run as root."

# ---------- Defaults (can be overridden by environment) ----------
MESH_ID=${MESH_ID:-stratumesh}
BASE_IF=${BASE_IF:-}           # leave empty to auto-detect below
MESH_IF=${MESH_IF:-mesh0}
PHY=${PHY:-}                   # leave empty to auto-detect from BASE_IF
HT_MODE=${HT_MODE:-HT40+}
COUNTRY=${COUNTRY:-DE}
BR_NAME=${BR_NAME:-br-mesh}

# ---------- Bring in your existing helper scripts ----------
# We source them relative to this script's directory so you can run from anywhere.
SCRIPT_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)

# freq.sh provides an associative array `chan` that maps channel → frequency MHz
#   e.g., chan[36]=5180
# node_addresses.sh / topology.sh are optional here but available for future use.
#   We don't consume IP maps directly in this bridge scenario, but having them
#   sourced early avoids surprises if you later extend the script (e.g., L3 on br).
source "$SCRIPT_DIR/freq.sh"             # provides: declare -A chan[...]  fileciteturn1file0
source "$SCRIPT_DIR/node_addresses.sh"   # provides MAC/IP maps & neighbors  fileciteturn1file1
source "$SCRIPT_DIR/topology.sh"         # provides set_topology()           fileciteturn1file2

# ---------- Utility helpers ----------
require_bin() { command -v "$1" >/dev/null 2>&1 || err "Missing dependency: $1"; }
iface_exists() { ip link show "$1" >/dev/null 2>&1; }
first_wifi_if() { iw dev 2>/dev/null | awk '/Interface/ {print $2}' | head -n1; }
get_phy_for_if() { local ifc=$1; iw dev "$ifc" info 2>/dev/null | awk '/wiphy/ {print "phy"$2; exit}'; }
flush_ip() { ip addr flush dev "$1" || true; }

set_regdom() { iw reg set "$COUNTRY" 2>/dev/null || true; }

apply_txpower() {
  # Set TX power in mBm (1 dBm = 100 mBm). Some drivers ignore fixed settings.
  local ifc=$1 dbm=$2; local mbm=$((dbm * 100))
  if iw dev "$ifc" set txpower fixed "$mbm" 2>/dev/null; then
    log "Set txpower on $ifc to ${dbm} dBm"
  else
    warn "Driver refused fixed txpower on $ifc; continuing"
  fi
}

apply_noise_floor_override() {
  # Best-effort for ath9k via debugfs. This does **not** exist on all kernels.
  local phy=$1 nf=$2
  local base="/sys/kernel/debug/ieee80211/${phy}/ath9k"
  if [[ -d "$base" ]]; then
    for f in nf_override noise_floor_override ani_noise_floor; do
      if [[ -w "$base/$f" ]]; then
        echo "$nf" > "$base/$f" || true
        log "Applied noise floor override $nf dBm via $base/$f"
        return 0
      fi
    done
    warn "ath9k debugfs present but no known NF override nodes writable"
  else
    warn "No ath9k debugfs at $base; skipping noise floor override"
  fi
}

cleanup_existing() {
  # Idempotent teardown so re-runs leave us in a good state.
  if iface_exists "$BR_NAME"; then
    log "Cleaning existing bridge $BR_NAME"
    # Detach ports before deleting the bridge (avoids lingering masters)
    for p in $(bridge link 2>/dev/null | awk -F': ' '/master '"$BR_NAME"'/ {print $2}' | awk '{print $1}'); do
      ip link set "$p" nomaster || true
    done
    ip link set "$BR_NAME" down || true
    ip link del "$BR_NAME" type bridge || true
  fi
  if iface_exists "$MESH_IF"; then
    log "Removing existing mesh interface $MESH_IF"
    ip link set "$MESH_IF" down || true
    iw dev "$MESH_IF" del || true
  fi
}

# ---------- Sanity checks ----------
require_bin ip
require_bin iw

# Verify eth2 exists early; we warn (and continue) if temporarily absent so the
# mesh can still come up. You can hot-plug eth2 later and re-run just the bridge
# part if needed.
if ! iface_exists eth2; then
  warn "Interface eth2 not present right now; proceeding with mesh-only, will still create bridge"
fi

# ---------- Auto-detect base Wi‑Fi interface & phy (unless provided) ----------
if [[ -z "$BASE_IF" ]]; then
  BASE_IF=$(first_wifi_if || true)
fi
[[ -n "$BASE_IF" ]] || err "Could not auto-detect a Wi‑Fi interface. Set BASE_IF=wlanX."

if [[ -z "$PHY" ]]; then
  PHY=$(get_phy_for_if "$BASE_IF" || true)
fi
[[ -n "$PHY" ]] || err "Could not resolve phy for $BASE_IF."

log "Host: $HOST_SHORT | base if: $BASE_IF | phy: $PHY | mesh if: $MESH_IF"

# ---------- Clean previous state (idempotency) ----------
cleanup_existing

# ---------- Regulatory setup and base bring-up ----------
set_regdom
ip link set "$BASE_IF" up || true

# ---------- Create the 802.11s mesh interface ----------
# We create a new interface of type 'mp' (mesh point) derived from BASE_IF.
log "Creating mesh interface $MESH_IF from $BASE_IF"
iw dev "$BASE_IF" interface add "$MESH_IF" type mp || err "Failed to create mesh interface"
ip link set "$MESH_IF" up

# ---------- Channel and mesh join ----------
# Use your freq map from freq.sh. If a channel is missing, we attempt a best-effort join.
FREQ_MHZ=${chan[$CHAN]:-}
if [[ -n "$FREQ_MHZ" ]]; then
  log "Joining mesh ID '$MESH_ID' on channel $CHAN (${FREQ_MHZ} MHz, $HT_MODE)"
  # Set channel + width first (where supported), then join specifying frequency.
  iw dev "$MESH_IF" set channel "$CHAN" $HT_MODE || true
  iw dev "$MESH_IF" mesh join "$MESH_ID" freq "$FREQ_MHZ" || err "mesh join failed"
else
  warn "Channel $CHAN not found in freq.sh; attempting join without explicit frequency"
  iw dev "$MESH_IF" mesh join "$MESH_ID" || err "mesh join failed"
fi

# ---------- RF tuning ----------
apply_txpower "$MESH_IF" "$POWER_DBM"
apply_noise_floor_override "$PHY" "$NOISE_FLOOR"

# ---------- Bridge creation: mesh <-> eth2 ----------
# Why bridge? Because we want transparent L2 forwarding between the Ethernet
# segment (eth2) and the wireless mesh (MESH_IF). The Linux bridge `BR_NAME`
# acts like a software switch connecting the two.
log "Creating bridge $BR_NAME and enslaving { $MESH_IF, eth2 }"
# Create the bridge (no STP by default; enable if you expect loops elsewhere)
ip link add name "$BR_NAME" type bridge || true
ip link set "$BR_NAME" up

# Enslave ports: flush any IPs (bridge members should be pure L2) and add to master
for p in "$MESH_IF" eth2; do
  if iface_exists "$p"; then
    ip link set "$p" up || true
    flush_ip "$p"
    ip link set "$p" master "$BR_NAME"
  else
    warn "Interface $p not present; skipping enslave for now"
  fi
done

# Optionally assign an IP to the BRIDGE itself (if you want L3 mgmt on this L2)
if [[ -n "${BR_MESH_ADDR:-}" && -n "${BR_MESH_PREFIX:-}" ]]; then
  ip addr add "${BR_MESH_ADDR}/${BR_MESH_PREFIX}" dev "$BR_NAME" || true
  log "Assigned ${BR_MESH_ADDR}/${BR_MESH_PREFIX} to $BR_NAME"
else
  log "No IP assigned to $BR_NAME (pure L2 bridge). Set BR_MESH_ADDR/BR_MESH_PREFIX if desired."
fi

# ---------- Final status snapshot (for quick troubleshooting) ----------
bridge link 2>/dev/null || true
ip -br addr show "$BR_NAME" || true
ip -br link show "$BR_NAME" "$MESH_IF" eth2 2>/dev/null || true

log "Mesh + bridge are up. You can now connect an Ethernet device to eth2 and reach it over the mesh."
exit 0