<#
.SYNOPSIS
    Moves VS Code user settings between this repo and the machine.

.DESCRIPTION
    -Push copies the machine's settings into User/ so you can commit them.
    -Pull copies User/ onto the machine, backing up whatever was there.
    -Diff says what differs without touching anything.

    This copies rather than symlinking on purpose. A symlink at
    %APPDATA%\Code\User\settings.json is fragile: an editor that saves atomically
    (write a temp file, rename it over the target) replaces the link with a regular
    file, and the sync silently stops without anything looking wrong. Copying is
    explicit -- you can see in git what changed and when.

    -Push also records your marketplace extensions in User/extensions.txt, and -Pull
    installs any that are missing. Ids starting "local." are skipped: those are the
    extensions in this repo, and install.ps1 gets them from the Gitea release.

.EXAMPLE
    .\scripts\settings.ps1 -Diff
    .\scripts\settings.ps1 -Push
    .\scripts\settings.ps1 -Pull
#>
[CmdletBinding(DefaultParameterSetName = 'Diff')]
param(
    [Parameter(ParameterSetName = 'Push', Mandatory)] [switch] $Push,
    [Parameter(ParameterSetName = 'Pull', Mandatory)] [switch] $Pull,
    [Parameter(ParameterSetName = 'Diff')] [switch] $Diff,
    [switch] $NoExtensions
)

Set-StrictMode -Version Latest
$ErrorActionPreference = 'Stop'
. (Join-Path $PSScriptRoot 'common.ps1')

$repoUser = Join-Path (Get-RepoRoot) 'User'
$codeUser = Get-CodeUserDir

if (-not (Test-Path $codeUser)) {
    throw ("VS Code's user folder was not found at $codeUser. If you use Insiders or a " +
           "portable install, set VSCODE_USER_DIR to it or copy by hand.")
}

# Only the things worth version-controlling. Everything else in User/ is state:
# globalStorage, workspaceStorage, History, sync, logs.
$items = @(
    @{ Name = 'settings.json';    Kind = 'File' },
    @{ Name = 'keybindings.json'; Kind = 'File' },
    @{ Name = 'tasks.json';       Kind = 'File' },
    @{ Name = 'snippets';         Kind = 'Directory' }
)

function Get-Fingerprint {
    param([string] $Path, [string] $Kind)
    if (-not (Test-Path $Path)) { return $null }
    if ($Kind -eq 'File') { return (Get-FileHash $Path -Algorithm SHA256).Hash }

    $parts = Get-ChildItem -Path $Path -Recurse -File | Sort-Object FullName | ForEach-Object {
        "$($_.FullName.Substring($Path.Length)):$((Get-FileHash $_.FullName -Algorithm SHA256).Hash)"
    }
    if (-not $parts) { return $null }
    $joined = $parts -join '|'
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($joined)
    $sha = [System.Security.Cryptography.SHA256]::Create()
    try {
        ([BitConverter]::ToString($sha.ComputeHash($bytes))) -replace '-', ''
    } finally { $sha.Dispose() }
}

function Copy-Item2 {
    param([string] $From, [string] $To, [string] $Kind)
    $parent = Split-Path -Parent $To
    if (-not (Test-Path $parent)) { New-Item -ItemType Directory -Path $parent -Force | Out-Null }

    if ($Kind -eq 'File') {
        Copy-Item -Path $From -Destination $To -Force
    } else {
        if (Test-Path $To) { Remove-Item -Path $To -Recurse -Force }
        Copy-Item -Path $From -Destination $To -Recurse -Force
    }
}

function Backup-Existing {
    param([string] $Path, [string] $Kind)
    if (-not (Test-Path $Path)) { return }
    $stamp = Get-Date -Format 'yyyyMMdd-HHmmss'
    $backup = "$Path.backup-$stamp"
    if ($Kind -eq 'File') {
        Copy-Item -Path $Path -Destination $backup -Force
    } else {
        Copy-Item -Path $Path -Destination $backup -Recurse -Force
    }
    Write-Host "    backed up to $(Split-Path -Leaf $backup)" -ForegroundColor DarkGray
}

$mode = $PSCmdlet.ParameterSetName
Write-Host "repo: $repoUser"
Write-Host "code: $codeUser"
Write-Host ''

foreach ($item in $items) {
    $inRepo = Join-Path $repoUser $item.Name
    $onDisk = Join-Path $codeUser $item.Name
    $repoPrint = Get-Fingerprint -Path $inRepo -Kind $item.Kind
    $diskPrint = Get-Fingerprint -Path $onDisk -Kind $item.Kind

    if (-not $repoPrint -and -not $diskPrint) {
        Write-Host "  $($item.Name): absent both sides" -ForegroundColor DarkGray
        continue
    }
    if ($repoPrint -eq $diskPrint) {
        Write-Host "  $($item.Name): identical" -ForegroundColor DarkGray
        continue
    }

    switch ($mode) {
        'Push' {
            if (-not $diskPrint) {
                Write-Host "  $($item.Name): not on this machine, leaving the repo copy alone" `
                    -ForegroundColor Yellow
                continue
            }
            Copy-Item2 -From $onDisk -To $inRepo -Kind $item.Kind
            Write-Host "  $($item.Name): machine -> repo" -ForegroundColor Green
        }
        'Pull' {
            if (-not $repoPrint) {
                Write-Host "  $($item.Name): not in the repo, leaving the machine alone" `
                    -ForegroundColor Yellow
                continue
            }
            Backup-Existing -Path $onDisk -Kind $item.Kind
            Copy-Item2 -From $inRepo -To $onDisk -Kind $item.Kind
            Write-Host "  $($item.Name): repo -> machine" -ForegroundColor Green
        }
        default {
            $where = if (-not $repoPrint) { 'only on this machine' }
                     elseif (-not $diskPrint) { 'only in the repo' }
                     else { 'differs' }
            Write-Host "  $($item.Name): $where" -ForegroundColor Yellow
        }
    }
}

if ($NoExtensions) { return }

Write-Host ''
$listPath = Join-Path $repoUser 'extensions.txt'
$code = Get-CodeCommand

if ($mode -eq 'Push') {
    $installed = @(& $code --list-extensions) |
        Where-Object { $_ -and $_ -notlike 'local.*' } |
        Sort-Object
    if (-not (Test-Path $repoUser)) { New-Item -ItemType Directory -Path $repoUser | Out-Null }
    Set-Content -Path $listPath -Value $installed -Encoding UTF8
    Write-Host "  extensions.txt: recorded $($installed.Count) marketplace extension(s)" `
        -ForegroundColor Green
    return
}

if (-not (Test-Path $listPath)) {
    Write-Host '  extensions.txt: not in the repo yet, run -Push on your main machine' `
        -ForegroundColor Yellow
    return
}

$wanted = @(Get-Content $listPath | Where-Object { $_ -and -not $_.StartsWith('#') })
$present = @(& $code --list-extensions)
$missing = @($wanted | Where-Object { $present -notcontains $_ })

if ($mode -eq 'Diff') {
    if ($missing.Count -eq 0) {
        Write-Host "  extensions.txt: all $($wanted.Count) present" -ForegroundColor DarkGray
    } else {
        Write-Host "  extensions.txt: $($missing.Count) missing: $($missing -join ', ')" `
            -ForegroundColor Yellow
    }
    return
}

if ($missing.Count -eq 0) {
    Write-Host "  extensions.txt: all $($wanted.Count) already installed" -ForegroundColor DarkGray
    return
}
foreach ($id in $missing) {
    Write-Host "  installing $id" -ForegroundColor DarkGray
    & $code --install-extension $id
}
Write-Host ''
Write-Host 'Reload the window to pick up new settings and extensions.' -ForegroundColor Cyan