param(
    [string]$Revision,
    [switch]$Force,
    [switch]$SkipBuild
)

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

function Invoke-CommandChecked {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Executable,
        [Parameter(Mandatory = $true)]
        [string[]]$Arguments
    )

    & $Executable @Arguments
    if ($LASTEXITCODE -ne 0) {
        throw "$Executable failed with exit code $LASTEXITCODE."
    }
}

function Get-PomProperty {
    param(
        [Parameter(Mandatory = $true)]
        [string]$PomText,
        [Parameter(Mandatory = $true)]
        [string]$Name
    )

    $escapedName = [Regex]::Escape($Name)
    $match = [Regex]::Match($PomText, "<$escapedName>([^<]+)</$escapedName>")
    if (-not $match.Success) {
        throw "Cannot find Maven property '$Name'."
    }

    return $match.Groups[1].Value.Trim()
}

function Sync-ProtoDirectory {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Source,
        [Parameter(Mandatory = $true)]
        [string]$Destination
    )

    if (-not (Test-Path -LiteralPath $Source -PathType Container)) {
        throw "Upstream proto directory does not exist: $Source"
    }

    New-Item -ItemType Directory -Path $Destination -Force | Out-Null

    $sourceFiles = @{}
    foreach ($sourceFile in Get-ChildItem -LiteralPath $Source -Filter '*.proto' -File -Recurse) {
        $relativePath = $sourceFile.FullName.Substring($Source.Length).TrimStart('\', '/')
        $sourceFiles[$relativePath] = $true

        $destinationFile = Join-Path $Destination $relativePath
        $destinationDirectory = Split-Path -Parent $destinationFile
        New-Item -ItemType Directory -Path $destinationDirectory -Force | Out-Null
        Copy-Item -LiteralPath $sourceFile.FullName -Destination $destinationFile -Force
    }

    foreach ($destinationFile in Get-ChildItem -LiteralPath $Destination -Filter '*.proto' -File -Recurse) {
        $relativePath = $destinationFile.FullName.Substring($Destination.Length).TrimStart('\', '/')
        if (-not $sourceFiles.ContainsKey($relativePath)) {
            Remove-Item -LiteralPath $destinationFile.FullName -Force
        }
    }
}

if (-not (Get-Command git -ErrorAction SilentlyContinue)) {
    throw 'Git was not found on PATH.'
}

$rootDirectory = Split-Path -Parent $PSScriptRoot
$moduleRelativePath = 'cmvr-iot-api/cmvr-iot-edge/cmvr-iot-grpc-lib'
$moduleDirectory = Join-Path $rootDirectory $moduleRelativePath
$pomPath = Join-Path $moduleDirectory 'pom.xml'
$protoRelativePath = "$moduleRelativePath/src/main/proto/cmvr"
$protoDirectory = Join-Path $rootDirectory $protoRelativePath
$checkoutDirectory = Join-Path $moduleDirectory 'target/cmvr-es'

$pomText = [IO.File]::ReadAllText($pomPath)
$repository = Get-PomProperty -PomText $pomText -Name 'cmvr.es.repository'
$branch = Get-PomProperty -PomText $pomText -Name 'cmvr.es.proto.branch'

$localProtoChanges = @(& git -C $rootDirectory status --porcelain -- $protoRelativePath)
if ($LASTEXITCODE -ne 0) {
    throw 'Unable to inspect local proto changes.'
}
if ($localProtoChanges.Count -gt 0 -and -not $Force) {
    throw "Local proto files have uncommitted changes. Commit/stash them first, or rerun with -Force.`n$($localProtoChanges -join "`n")"
}

if ([string]::IsNullOrWhiteSpace($Revision)) {
    Write-Host "Looking up the latest '$branch' revision..."
    $remoteLine = @(& git ls-remote $repository "refs/heads/$branch")
    if ($LASTEXITCODE -ne 0) {
        throw 'Unable to read the upstream branch. Check the network and Git credentials.'
    }
    if ($remoteLine.Count -ne 1) {
        throw "Upstream branch '$branch' was not found or was ambiguous."
    }
    $Revision = ($remoteLine[0] -split '\s+')[0]
}

if ($Revision -notmatch '^[0-9a-fA-F]{40}$') {
    throw "Revision must be a full 40-character Git commit SHA: $Revision"
}
$Revision = $Revision.ToLowerInvariant()

$checkoutParent = Split-Path -Parent $checkoutDirectory
New-Item -ItemType Directory -Path $checkoutParent -Force | Out-Null

if (Test-Path -LiteralPath (Join-Path $checkoutDirectory '.git') -PathType Container) {
    Write-Host 'Refreshing the existing upstream checkout...'
    Invoke-CommandChecked git @('-C', $checkoutDirectory, 'remote', 'set-url', 'origin', $repository)
    Invoke-CommandChecked git @('-C', $checkoutDirectory, 'fetch', '--filter=blob:none', 'origin', $branch)
} else {
    if (Test-Path -LiteralPath $checkoutDirectory) {
        $expectedPath = [IO.Path]::GetFullPath($checkoutDirectory).TrimEnd('\')
        $actualPath = (Resolve-Path -LiteralPath $checkoutDirectory).Path.TrimEnd('\')
        if ($actualPath -ne $expectedPath -or (Split-Path -Parent $actualPath) -ne [IO.Path]::GetFullPath($checkoutParent).TrimEnd('\')) {
            throw "Refusing to replace unexpected checkout path: $actualPath"
        }
        Remove-Item -LiteralPath $checkoutDirectory -Recurse -Force
    }

    Write-Host 'Cloning the upstream proto repository...'
    Invoke-CommandChecked git @(
        'clone', '--filter=blob:none', '--sparse', '--single-branch',
        '--branch', $branch, $repository, $checkoutDirectory
    )
}

Invoke-CommandChecked git @(
    '-C', $checkoutDirectory, 'sparse-checkout', 'set',
    'protos/cmvr/api', 'protos/cmvr/msgs', 'protos/cmvr/common'
)
Invoke-CommandChecked git @('-C', $checkoutDirectory, 'checkout', '--detach', $Revision)

$actualRevision = (& git -C $checkoutDirectory rev-parse HEAD).Trim()
if ($LASTEXITCODE -ne 0 -or $actualRevision -ne $Revision) {
    throw "Expected revision $Revision, but checked out $actualRevision."
}

Write-Host "Syncing proto files from revision $Revision..."
foreach ($group in @('api', 'msgs', 'common')) {
    Sync-ProtoDirectory `
        -Source (Join-Path $checkoutDirectory "protos/cmvr/$group") `
        -Destination (Join-Path $protoDirectory $group)
}

$revisionPattern = '(<cmvr\.es\.proto\.revision>)[^<]+(</cmvr\.es\.proto\.revision>)'
$revisionRegex = [Regex]::new($revisionPattern)
$updatedPomText = $revisionRegex.Replace($pomText, "`${1}$Revision`${2}", 1)
if ($updatedPomText -eq $pomText -and (Get-PomProperty -PomText $pomText -Name 'cmvr.es.proto.revision') -ne $Revision) {
    throw 'Unable to update cmvr.es.proto.revision in pom.xml.'
}
if ($updatedPomText -ne $pomText) {
    [IO.File]::WriteAllText($pomPath, $updatedPomText, [Text.UTF8Encoding]::new($false))
}

Write-Host ''
Write-Host 'Updated files:'
& git -C $rootDirectory status --short -- $protoRelativePath "$moduleRelativePath/pom.xml"
if ($LASTEXITCODE -ne 0) {
    throw 'Unable to show the update summary.'
}

if (-not $SkipBuild) {
    if (-not (Get-Command mvn -ErrorAction SilentlyContinue)) {
        throw 'Maven was not found on PATH. Proto files were updated, but the verification build was not run.'
    }

    Write-Host ''
    Write-Host 'Running the gRPC verification build...'
    Push-Location $rootDirectory
    try {
        Invoke-CommandChecked mvn @(
            '-pl', 'cmvr-iot-api/cmvr-iot-edge/cmvr-iot-grpc-client',
            '-am', 'clean', 'package', '-DskipTests'
        )
    } finally {
        Pop-Location
    }
}

Write-Host ''
Write-Host "CMVR-ES proto update completed: $Revision"
Write-Host 'Review and commit the proto files and pom.xml together.'