param(
    [Parameter(Mandatory = $true)]
    [string]$Message,
    [string]$RepositoryRoot = ''
)

$ErrorActionPreference = 'Stop'

if ([string]::IsNullOrWhiteSpace($RepositoryRoot)) {
    $RepositoryRoot = (Get-Location).Path
}
$RepositoryRoot = [System.IO.Path]::GetFullPath($RepositoryRoot)
$gitRoot = & git -C $RepositoryRoot rev-parse --show-toplevel 2>$null | Select-Object -First 1
if ($LASTEXITCODE -ne 0 -or [string]::IsNullOrWhiteSpace($gitRoot)) {
    Write-Error "Git repository was not found: $RepositoryRoot"
    exit 1
}
$RepositoryRoot = [System.IO.Path]::GetFullPath($gitRoot)

$mappingFile = Join-Path $PSScriptRoot 'commit-module-mappings.json'
$mapping = Get-Content -LiteralPath $mappingFile -Raw -Encoding UTF8 | ConvertFrom-Json

function Get-CommitFiles {
    param([string]$Root)

    $staged = @(& git -C $Root -c core.quotepath=false diff --cached --name-only --diff-filter=ACMRD)
    $staged = @($staged | Where-Object { -not [string]::IsNullOrWhiteSpace($_) })
    if ($staged.Count -gt 0) {
        return $staged
    }

    $files = @()
    $statusLines = & git -C $Root -c core.quotepath=false status --porcelain=v1 --untracked-files=all
    foreach ($line in $statusLines) {
        if ([string]::IsNullOrWhiteSpace($line) -or $line.Length -lt 4) {
            continue
        }
        $path = $line.Substring(3).Trim()
        if ($path.Contains(' -> ')) {
            $path = ($path -split ' -> ')[-1]
        }
        $files += $path.Replace('\', '/')
    }
    return @($files | Select-Object -Unique)
}

function Get-Modules {
    param([string[]]$Files)

    $modules = @()
    foreach ($file in $Files) {
        foreach ($entry in $mapping.mappings) {
            if ($file -match $entry.pattern) {
                $modules += $entry.module
                break
            }
        }
    }
    return @($modules | Select-Object -Unique)
}

if ($Message -notmatch '^\[([^\]]+)\]\[([^\]]+)\]:\s+(.+)$') {
    Write-Error 'Commit message format must be: [module][type]: description'
    exit 1
}

$messageModule = $Matches[1]
$messageType = $Matches[2]
$description = $Matches[3]
if ([string]::IsNullOrWhiteSpace($description)) {
    Write-Error 'Commit message description is empty.'
    exit 1
}
if ($mapping.validTypes -notcontains $messageType) {
    Write-Error ("Invalid commit type '{0}'. Allowed types: {1}" -f
        $messageType, ($mapping.validTypes -join ', '))
    exit 1
}

$files = @(Get-CommitFiles $RepositoryRoot)
$modules = @(Get-Modules $files)

Write-Output ("Repository: {0}" -f $RepositoryRoot)
if ($files.Count -eq 0) {
    Write-Warning 'No staged, unstaged, or untracked files were found. Only the message was validated.'
}
else {
    Write-Output 'Commit scope files:'
    foreach ($file in $files) {
        Write-Output ("  - {0}" -f $file)
    }
}

if ($modules.Count -gt 0) {
    Write-Output ("Detected modules: {0}" -f ($modules -join ', '))
    if ($modules -notcontains $messageModule) {
        Write-Warning ("Message module [{0}] does not match detected modules [{1}]. Review the commit scope." -f
            $messageModule, ($modules -join ', '))
    }
}
else {
    Write-Warning 'No path mapping matched. Review the commit module manually.'
}

Write-Output 'Commit message is valid.'
exit 0