Param(
  [string]$Root = "."
)

$ErrorActionPreference = "Stop"

$files = Get-ChildItem -Path $Root -Recurse -Filter *.md | Where-Object { $_.FullName -notmatch '\\archive\\' }
$had = $false
foreach ($f in $files) {
  try {
    $lines = Get-Content -LiteralPath $f.FullName -Encoding UTF8 -ErrorAction Stop
  } catch {
    Write-Warning ("Impossible de lire: {0} — {1}" -f $f.FullName, $_.Exception.Message)
    continue
  }
  $map = @{}
  $firstMap = @{}
  $dups = @{}
  for ($i = 0; $i -lt $lines.Count; $i++) {
    $line = $lines[$i]
    if ($line -match '^\s{0,3}#{1,6}\s+(.*)$') {
      $t = $Matches[1].Trim()
      $norm = ([regex]::Replace($t, '\s+', ' ')).ToLowerInvariant()
      if ($map.ContainsKey($norm)) {
        if (-not $dups.ContainsKey($norm)) {
          $dups[$norm] = New-Object System.Collections.ArrayList
          $firstMap[$norm] = $map[$norm]
        }
        [void]$dups[$norm].Add($i + 1)
      } else {
        $map[$norm] = $i + 1
      }
    }
  }
  if ($dups.Keys.Count -gt 0) {
    $had = $true
    Write-Output "=== $($f.FullName) ==="
    foreach ($k in $dups.Keys) {
      $first = $firstMap[$k]
      $others = ($dups[$k] -join ', ')
      Write-Output ("Heading: '{0}' first@{1} duplicates@[{2}]" -f $k, $first, $others)
    }
  }
}
if (-not $had) {
  Write-Output "No duplicate headings detected."
}