#!/bin/sh
# 50-network.sh — Configure networking
# Priority: cloud-init (stage 45) > saved config > DHCP fallback

# If cloud-init already configured networking, skip this stage
if [ "$CLOUDINIT_APPLIED" = "1" ]; then
    log "Network already configured by cloud-init — skipping"
    return 0
fi

# Check for saved network config (from previous boot or cloud-init)
if [ -f "$DATA_MOUNT/network/interfaces.sh" ]; then
    log "Applying saved network configuration"
    . "$DATA_MOUNT/network/interfaces.sh"
    return 0
fi

# Fallback: DHCP on first non-loopback interface
log "Configuring network via DHCP"

# Bring up loopback (use ifconfig for BusyBox compatibility)
ifconfig lo 127.0.0.1 netmask 255.0.0.0 up 2>/dev/null || \
    { ip link set lo up 2>/dev/null && ip addr add 127.0.0.1/8 dev lo 2>/dev/null; } || true

# Find first ethernet interface
ETH_DEV=""
for iface in /sys/class/net/*; do
    iface="$(basename "$iface")"
    case "$iface" in
        lo|docker*|veth*|br*|cni*|dummy*|tunl*|sit*) continue ;;
    esac
    ETH_DEV="$iface"
    break
done

if [ -z "$ETH_DEV" ]; then
    log_err "No network interface found"
    return 1
fi

log "Using interface: $ETH_DEV"
ifconfig "$ETH_DEV" up 2>/dev/null || ip link set "$ETH_DEV" up 2>/dev/null || true

# Run DHCP client (BusyBox udhcpc)
if command -v udhcpc >/dev/null 2>&1; then
    udhcpc -i "$ETH_DEV" -s /usr/share/udhcpc/default.script \
        -t 10 -T 3 -A 5 -b -q 2>/dev/null || {
        log_err "DHCP failed on $ETH_DEV"
        return 1
    }
elif command -v dhcpcd >/dev/null 2>&1; then
    dhcpcd "$ETH_DEV" || {
        log_err "DHCP failed on $ETH_DEV"
        return 1
    }
else
    log_err "No DHCP client available (need udhcpc or dhcpcd)"
    return 1
fi

# Ensure /etc/resolv.conf has valid DNS (udhcpc should have written it,
# but verify and add fallbacks if missing)
if [ ! -s /etc/resolv.conf ]; then
    log_warn "/etc/resolv.conf is empty — adding fallback DNS"
    echo "nameserver 10.0.2.3" > /etc/resolv.conf
    echo "nameserver 8.8.8.8" >> /etc/resolv.conf
elif ! grep -q nameserver /etc/resolv.conf 2>/dev/null; then
    log_warn "No nameserver in /etc/resolv.conf — adding fallback DNS"
    echo "nameserver 10.0.2.3" >> /etc/resolv.conf
    echo "nameserver 8.8.8.8" >> /etc/resolv.conf
fi

log_ok "Network configured on $ETH_DEV (DNS: $(grep nameserver /etc/resolv.conf 2>/dev/null | head -1))"