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

    Fault : "Operating system not found" or "No bootable device"
    Fix   : Rebuild the EFI system partition
    Source: https://jbtecwiz.com/support/win-rec-os-not-found

    Run as     : WinRE Command Prompt
    Expect     : 45 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    UEFI mode is correct and the boot entry has still gone -- commonly after
    a Linux install, a partition tool, or a clone.

    HOW TO UNDO IT
    Take an image of the disk before creating partitions. bcdboot itself
    only writes boot files.

    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 5"
    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 '  "Operating system not found" or "No bootable device"' -ForegroundColor White
Write-Host '  Rebuild the EFI system partition' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   45 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 'Identify the Windows volume and the EFI partition. The EFI one is small, FAT32, and usually hidden.' -Command {
    cmd.exe /c 'diskpart & list volume'
}

Invoke-Step -Number 2 -Do 'Give the EFI partition a letter.' -Command {
    cmd.exe /c 'sel vol 2 & assign letter=S: & exit'
}

Invoke-Step -Number 3 -Do 'Write a fresh boot store from the Windows installation.' -Why 'This is the whole repair in one command. It creates the EFI directory structure and the boot configuration from the installed Windows, which is far more reliable than trying to patch a damaged store.' -Command {
    cmd.exe /c 'bcdboot D:\Windows /s S: /f UEFI /l en-gb'
}

Invoke-Step -Number 4 -Do 'If the EFI partition is missing entirely, create one of 100-500MB, format it FAT32, and then run bcdboot.' -Command {
    cmd.exe /c 'diskpart & sel disk 0 & create partition efi size=260 & format quick fs=fat32 label=SYSTEM & assign letter=S: & exit'
}

Invoke-Step -Number 5 -Do 'Remove the drive letter and restart.' -Command {
    cmd.exe /c 'diskpart & sel vol 2 & remove letter=S: & exit'
}

Write-Rule "  Confirm it worked"
Show-Prose 'The machine boots, and the boot store lists a single valid Windows entry.' 'White'
Write-Host ''
if (-not $DryRun) {
    cmd.exe /c 'bcdedit /enum firmware'
}

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-rec-os-not-found' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Take an image of the disk before creating partitions. bcdboot itself only writes boot files.' 'DarkGray'
Write-Rule