# Copyright 2014 The Flutter Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# Based on the current repository state, writes the following two files to disk:
#
# bin/cache/engine.stamp <-- SHA of the commit that engine artifacts were built
# bin/cache/engine.realm <-- optional; ; whether the SHA is from presubmit builds or staging (bringup: true).
#
# *DOES NOT* update engine.version.

# ---------------------------------- NOTE ---------------------------------- #
#
# Please keep the logic in this file consistent with the logic in the
# `update_engine_version.sh` script in the same directory to ensure that Flutter
# continues to work across all platforms!
#
# https://github.com/flutter/flutter/blob/main/docs/tool/Engine-artifacts.md.
#
# Want to test this script?
# $ cd dev/tools
# $ dart test test/update_engine_version_test.dart
#
# -------------------------------------------------------------------------- #

$ErrorActionPreference = "Stop"

# When called from a submodule hook; these will override `git -C dir`
$env:GIT_DIR = $null
$env:GIT_INDEX_FILE = $null
$env:GIT_WORK_TREE = $null

$progName = Split-Path -parent $MyInvocation.MyCommand.Definition
$flutterRoot = (Get-Item $progName).parent.parent.FullName

# Generate a bin/cache directory, which won't initially exist for a fresh checkout.
New-Item -Path "$flutterRoot/bin/cache" -ItemType Directory -Force | Out-Null

# Check if FLUTTER_PREBUILT_ENGINE_VERSION is set
#
# This is intended for systems where we intentionally want to (ephemerally) use
# a specific engine artifacts version (which includes the Flutter engine and
# the Dart SDK), such as on CI.
#
# If set, it takes precedence over any other source of engine version.
if (![string]::IsNullOrEmpty($env:FLUTTER_PREBUILT_ENGINE_VERSION)) {
  $engineVersion = $env:FLUTTER_PREBUILT_ENGINE_VERSION

# Check if bin/internal/engine.version exists and is a tracked file in git.
#
# This is intended for a user-shipped stable or beta release, where the release
# has a specific (pinned) engine artifacts version.
#
# If set, it takes precedence over the git hash.
} elseif (git -C "$flutterRoot" ls-files bin/internal/engine.version) {
  $engineVersion = Get-Content -Path "$flutterRoot/bin/internal/engine.version"

# Fallback to using git to triangulate which upstream/master (or origin/master)
# the current branch is forked from, which would be the last version of the
# engine artifacts built from CI.
} else {
  $engineVersion = Invoke-Expression "& '$flutterRoot/bin/internal/content_aware_hash.ps1'"
}

# Write the engine version out so downstream tools know what to look for.
# Use a temporary file and a retry logic to minimize chances of a race condition during
# parallel flutter executions.
$esTmp = "$flutterRoot/bin/cache/engine.stamp.tmp.$PID"
try {
    Set-Content -Path $esTmp -Value $engineVersion -Encoding Ascii
    $retryCount = 0
    while ($true) {
        try {
            Move-Item -Path $esTmp -Destination "$flutterRoot/bin/cache/engine.stamp" -Force
            break
        } catch {
            if ($retryCount -ge 2) {
                throw
            }
            $retryCount++
            Start-Sleep -Milliseconds 50
        }
    }
} finally {
    if (Test-Path -Path $esTmp) {
        Remove-Item -Path $esTmp -Force -ErrorAction SilentlyContinue
    }
}

# The realm on CI is passed in.
if ($env:FLUTTER_REALM) {
    Set-Content -Path $flutterRoot/bin/cache/engine.realm -Value $env:FLUTTER_REALM -Encoding Ascii
} else {
    Set-Content -Path $flutterRoot/bin/cache/engine.realm -Value "" -Encoding Ascii
}