[CmdletBinding()]
param(
    [string]$RootPath = "C:\Users\stefan\git",
    [string]$StandardsRepoPath = "C:\Users\stefan\git\project-standards",
    [string[]]$Exclude = @('project-standards'),
    [switch]$CheckOnly,
    [switch]$Watch,
    [int]$IntervalSeconds = 60
)

Set-StrictMode -Version Latest
$ErrorActionPreference = 'Stop'

$agentsTemplate = Join-Path $StandardsRepoPath 'templates/AGENTS.base.md'
$dodTemplate = Join-Path $StandardsRepoPath 'templates/DEFINITION_OF_DONE.base.md'

if (-not (Test-Path -Path $agentsTemplate -PathType Leaf)) {
    throw "AGENTS template not found: $agentsTemplate"
}

if (-not (Test-Path -Path $dodTemplate -PathType Leaf)) {
    throw "DoD template not found: $dodTemplate"
}

if ($IntervalSeconds -lt 5) {
    throw 'IntervalSeconds must be >= 5.'
}

function Get-ContentHashOrMissing {
    param([string]$Path)

    if (-not (Test-Path -Path $Path -PathType Leaf)) {
        return '__MISSING__'
    }

    return (Get-FileHash -Path $Path -Algorithm SHA256).Hash
}

function Ensure-FileFromTemplate {
    param(
        [string]$Template,
        [string]$Target,
        [switch]$OnlyCheck
    )

    $templateHash = Get-ContentHashOrMissing -Path $Template
    $targetHash = Get-ContentHashOrMissing -Path $Target

    if ($templateHash -eq $targetHash) {
        return 'ok'
    }

    if ($OnlyCheck) {
        return 'drift'
    }

    $parent = Split-Path -Parent $Target
    if (-not (Test-Path -Path $parent -PathType Container)) {
        New-Item -ItemType Directory -Path $parent | Out-Null
    }

    Copy-Item -Path $Template -Destination $Target -Force
    return 'updated'
}

function Invoke-ReconcileOnce {
    param([switch]$OnlyCheck)

    $resolvedRoot = (Resolve-Path -Path $RootPath -ErrorAction Stop).Path
    $repos = Get-ChildItem -Path $resolvedRoot -Directory | Where-Object {
        $Exclude -notcontains $_.Name
    }

    $summary = [ordered]@{
        scanned = 0
        updated = 0
        drift = 0
    }

    foreach ($repo in $repos) {
        $repoPath = $repo.FullName
        $agentsTarget = Join-Path $repoPath 'AGENTS.md'
        $dodTarget = Join-Path (Join-Path $repoPath 'docs') 'DEFINITION_OF_DONE.md'

        $summary.scanned++

        $agentsState = Ensure-FileFromTemplate -Template $agentsTemplate -Target $agentsTarget -OnlyCheck:$OnlyCheck
        $dodState = Ensure-FileFromTemplate -Template $dodTemplate -Target $dodTarget -OnlyCheck:$OnlyCheck

        if ($agentsState -eq 'updated' -or $dodState -eq 'updated') {
            $summary.updated++
            Write-Host "UPDATED: $repoPath"
            continue
        }

        if ($agentsState -eq 'drift' -or $dodState -eq 'drift') {
            $summary.drift++
            Write-Host "DRIFT:   $repoPath"
            continue
        }

        Write-Host "OK:      $repoPath"
    }

    Write-Host "Summary -> scanned=$($summary.scanned), updated=$($summary.updated), drift=$($summary.drift)"
    return $summary
}

if ($Watch) {
    while ($true) {
        $now = Get-Date -Format 'yyyy-MM-dd HH:mm:ss'
        Write-Host "[$now] Reconciling project standards..."
        [void](Invoke-ReconcileOnce -OnlyCheck:$CheckOnly)
        Start-Sleep -Seconds $IntervalSeconds
    }
}

$result = Invoke-ReconcileOnce -OnlyCheck:$CheckOnly
if ($CheckOnly -and $result.drift -gt 0) {
    exit 1
}