# configure.ps1 -- the per-pod install step, called by postinstall.bat (elevated).
# On THIS machine it: finds the NIC + its static IP (the bay IP), derives the
# DOSBox game IP = bayIP + 100, binds DOSBox's pcap to the NIC, renders the
# net_*.conf templates, and stamps the WATTCP.CFG my_ip. Air-gapped, static,
# <=32 pods. See ../DEPLOYMENT-PLAN.md.
param([Parameter(Mandatory = $true)][string]$Root)
$ErrorActionPreference = 'Stop'
function Log($m) { Write-Host "[configure] $m" }

# --- prefix length -> dotted netmask -------------------------------------
function PrefixToMask([int]$p) {
    $bits = ('1' * $p).PadRight(32, '0')
    $o = 0..3 | ForEach-Object { [Convert]::ToInt32($bits.Substring($_ * 8, 8), 2) }
    return ($o -join '.')
}

# --- 1. the pod's NIC + bay IP (the one real static IPv4) ----------------
$ip = Get-NetIPAddress -AddressFamily IPv4 |
    Where-Object { $_.IPAddress -notlike '127.*' -and $_.IPAddress -notlike '169.254.*' } |
    Sort-Object -Property SkipAsSource, InterfaceMetric |
    Select-Object -First 1
if (-not $ip) { throw "no usable static IPv4 found on any adapter" }
$bayIp   = $ip.IPAddress
$ifIndex = $ip.InterfaceIndex
$adapter = Get-NetAdapter -InterfaceIndex $ifIndex
$guid    = $adapter.InterfaceGuid.Trim('{', '}')
$mask    = PrefixToMask $ip.PrefixLength
Log "bay IP $bayIp/$($ip.PrefixLength) on '$($adapter.Name)' guid $guid"

# --- 2. realnic fragment. Must be a CONTIGUOUS substring of the pcap device
#        name (\Device\NPF_{GUID}, hyphens included), so take it from ONE
#        hyphen-delimited GUID block -- letter-leading (DOSBox reads a leading
#        DIGIT as an interface index) and length >= 6 for uniqueness. Longest. --
$realnic = $null
foreach ($blk in ($guid -split '-')) {
    $mm = [regex]::Match($blk, '[A-Fa-f][0-9A-Fa-f]{5,}')
    if ($mm.Success -and (-not $realnic -or $mm.Value.Length -gt $realnic.Length)) { $realnic = $mm.Value }
}
if (-not $realnic) { throw "no letter-leading >=6-char realnic fragment in any block of GUID $guid" }
Log "realnic fragment = $realnic"

# --- 3. game IP = bay IP + 100 on the last octet -------------------------
$o = $bayIp.Split('.')
$last = [int]$o[3] + 100
if ($last -gt 254) { throw "bay last octet $($o[3]) + 100 = $last overflows 254; keep bays <= .100" }
$gameIp = "$($o[0]).$($o[1]).$($o[2]).$last"
Log "game IP = $gameIp  (bay + 100)"

# --- 4. stable locally-administered MAC from the game IP ------------------
$mac = "02:00:{0:X2}:{1:X2}:{2:X2}:{3:X2}" -f [int]$o[0], [int]$o[1], [int]$o[2], $last
Log "macaddr = $mac"

# --- 5. gateway/nameserver: the host's real gateway if set, else the host
#        itself (always up + on-subnet -> WATTCP's boot ARP resolves; never
#        actually routed, the mesh is same-subnet L2) -----------------------
$gw = $null
try { $gw = (Get-NetIPConfiguration -InterfaceIndex $ifIndex).IPv4DefaultGateway.NextHop } catch { }
if (-not $gw) { $gw = $bayIp }
Log "gateway/nameserver = $gw"

# --- 6. render the conf templates (@@ROOT@@/@@REALNIC@@/@@MACADDR@@) ------
$tokens = @{ '@@ROOT@@' = $Root; '@@REALNIC@@' = $realnic; '@@MACADDR@@' = $mac }
$tmpls = Get-ChildItem -Path $Root -Filter '*.conf.tmpl' -ErrorAction SilentlyContinue
if (-not $tmpls) { throw "no *.conf.tmpl found in $Root" }
foreach ($t in $tmpls) {
    $text = Get-Content -Path $t.FullName -Raw
    foreach ($k in $tokens.Keys) { $text = $text.Replace($k, $tokens[$k]) }
    $out = Join-Path $Root ($t.Name -replace '\.tmpl$', '')
    Set-Content -Path $out -Value $text -Encoding Ascii -NoNewline
    Log "rendered $($t.Name -replace '\.tmpl$','')"
}

# --- 7. stamp WATTCP.CFG my_ip = game IP (all copies the game may read) ---
$wattcp = @(
    (Join-Path $Root 'ALPHA_1\REL410\BT\WATTCP.CFG'),
    (Join-Path $Root 'ALPHA_1\REL410\RP\WATTCP.CFG'),
    (Join-Path $Root 'ALPHA_1\VGL_LABS\THISPOD\WATTCP.CFG')
)
$lines = @("my_ip = $gameIp", "netmask = $mask", "nameserver = $gw", "gateway = $gw")
$stamped = 0
foreach ($w in $wattcp) {
    if (Test-Path $w) { Set-Content -Path $w -Value $lines -Encoding Ascii; $stamped++; Log "stamped $w" }
}
if ($stamped -eq 0) { throw "no WATTCP.CFG found under $Root\ALPHA_1" }

Log "OK: bay=$bayIp game=$gameIp mac=$mac realnic=$realnic ($stamped WATTCP.CFG)"