# Resolves module dependency tree via proxy.golang.org and fetches sum.golang.org lines.
# Appends missing entries to go.sum (run from repo root: pwsh -File scripts/expand-go-sum.ps1).

Set-StrictMode -Version 3
$ErrorActionPreference = "Stop"

# Escape module path for sum.golang.org / proxy.golang.org (lowercase + %XX for other UTF-8 bytes).
function Escape-GoModulePath2([string]$path) {
    $lower = $path.ToLowerInvariant()
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($lower)
    $sb = New-Object System.Text.StringBuilder
    foreach ($b in $bytes) {
        $c = [char]$b
        $ok = ($b -ge 48 -and $b -le 57) -or ($b -ge 97 -and $b -le 122) -or ($c -eq '-') -or ($c -eq '.') -or ($c -eq '_') -or ($c -eq '+')
        if ($ok) {
            [void]$sb.Append($c)
        }
        else {
            [void]$sb.AppendFormat("%{0:x2}", $b)
        }
    }
    return $sb.ToString()
}

function Get-SumdbLines([string]$modPath, [string]$ver) {
    $enc = Escape-GoModulePath2 $modPath
    $url = "https://sum.golang.org/lookup/$enc@$ver"
    $raw = (Invoke-WebRequest -Uri $url -UseBasicParsing).Content
    $out = New-Object System.Collections.Generic.List[string]
    foreach ($line in ($raw -split "`n")) {
        $t = $line.Trim()
        if ($t -match '^\S+\s+v\S+\s+h1:') {
            [void]$out.Add($t)
        }
    }
    return $out
}

function Get-GoMod([string]$modPath, [string]$ver) {
    $enc = Escape-GoModulePath2 $modPath
    $url = "https://proxy.golang.org/$enc/@v/$ver.mod"
    return (Invoke-WebRequest -Uri $url -UseBasicParsing).Content
}

function Parse-Requires([string]$modText) {
    $req = @()
    $inBlock = $false
    foreach ($line in ($modText -split "`n")) {
        $t = $line.Trim()
        if ($t.StartsWith("//")) { continue }
        if ($t -match '^require\s+\(\s*$') { $inBlock = $true; continue }
        if ($inBlock) {
            if ($t -eq ")") { $inBlock = $false; continue }
            if ($t -match '^(\S+)\s+(v[^\s]+)') {
                $req += ,@($Matches[1], $Matches[2])
            }
            continue
        }
        if ($t -match '^require\s+(\S+)\s+(v[^\s]+)\s*(//.*)?$') {
            $req += ,@($Matches[1], $Matches[2])
        }
    }
    return $req
}

$root = Split-Path -Parent $PSScriptRoot
Set-Location $root

$queue = [System.Collections.Queue]::new()
$seen = @{}
$allLines = [System.Collections.Generic.HashSet[string]]::new([StringComparer]::Ordinal)

foreach ($line in Get-Content -Path (Join-Path $root "go.sum")) {
    if ($line.Trim()) { [void]$allLines.Add($line.Trim()) }
}

function Enqueue([string]$p, [string]$v) {
    if ([string]::IsNullOrWhiteSpace($p) -or [string]::IsNullOrWhiteSpace($v)) { return }
    if ($p -notmatch '\.') { return }
    $k = "$p@$v"
    if ($seen.ContainsKey($k)) { return }
    $seen[$k] = $true
    $queue.Enqueue($k)
}

# Seed from go.mod direct requires (edit if go.mod changes)
Enqueue "github.com/google/uuid" "v1.6.0"
Enqueue "github.com/jackc/pgx/v5" "v5.7.2"
Enqueue "github.com/prometheus/client_golang" "v1.20.5"
Enqueue "modernc.org/sqlite" "v1.34.5"

while ($queue.Count -gt 0) {
    $item = $queue.Dequeue()
    $p, $v = $item.Split("@", 2)

    foreach ($ln in (Get-SumdbLines $p $v)) {
        [void]$allLines.Add($ln)
    }

    $modBody = Get-GoMod $p $v
    foreach ($pair in (Parse-Requires $modBody)) {
        Enqueue $pair[0] $pair[1]
    }
}

$ordered = @($allLines | Sort-Object)
$pathSum = Join-Path $root "go.sum"
$utf8NoBom = New-Object System.Text.UTF8Encoding $false
[System.IO.File]::WriteAllLines($pathSum, $ordered, $utf8NoBom)
Write-Host "go.sum written: $($ordered.Count) lines"