#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : Teams will not load, shows a white screen, or is stuck signing in
    Fix   : Clear the classic Teams cache
    Source: https://jbtecwiz.com/support/win-app-teams-cache

    Run as     : PowerShell as the affected user
    Expect     : 20 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    Classic Teams, which stores its cache in the user profile.

    HOW TO UNDO IT
    The cache rebuilds itself. Nothing that only exists locally is lost.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 4"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  Teams will not load, shows a white screen, or is stuck signing in' -ForegroundColor White
Write-Host '  Clear the classic Teams cache' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   20 minutes'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'Close Teams from the notification area and confirm no process remains.' -Command {
    Get-Process Teams -ErrorAction SilentlyContinue | Stop-Process -Force
}

Invoke-Step -Number 2 -Do 'Clear the cache directories.' -Why 'These are the directories that hold the rendered state and the local database. Deleting the whole Teams folder also removes the settings and the desktop configuration, which is more disruptive than necessary.' -Command {
    $t = "$env:APPDATA\Microsoft\Teams"
    'blob_storage','Cache','Code Cache','databases','GPUCache','IndexedDB','Local Storage','tmp' |
      ForEach-Object { Remove-Item "$t\$_" -Recurse -Force -ErrorAction SilentlyContinue }
}

Invoke-Step -Number 3 -Do 'Clear the Teams credential entries.' -Command {
    cmdkey /list | ForEach-Object { if ($_ -match 'Target:\s*(\S*[Tt]eams\S*)') { cmdkey /delete:$($Matches[1]) } }
}

Invoke-Step -Number 4 -Do 'Start Teams and sign in. The first start after a cache clear is slow.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'Teams loads to the chat list within a minute or two and stays signed in after a restart.' 'White'

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/win-app-teams-cache' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: The cache rebuilds itself. Nothing that only exists locally is lost.' 'DarkGray'
Write-Rule