<#
.SYNOPSIS
Checks a web repository for a new version based on a version file.
If newer, downloads all files listed in a manifest file from the repository,
replacing local files and creating necessary subdirectories.

.DESCRIPTION
This script compares a local version.txt file with one on a web server.
If the web server version is newer, it downloads a manifest.txt file from the server.
It then iterates through the manifest, downloading each listed file/path to the
local script directory ($PSScriptRoot), creating subdirectories as needed.

.NOTES
Author: [Your Name/Company]
Date:   [Current Date]
Requires: PowerShell 3.0 or later (for Invoke-WebRequest).
          Internet connectivity to the web repository.
          A 'version.txt' file in the web repository containing the latest version string.
          A 'manifest.txt' file in the web repository listing all files/relative paths to download (one per line).

.EXAMPLE
.\Update.ps1
Runs the update check from the default web repository.
#>

# --- Configuration ---

# Web repository path (Ensure spaces are properly encoded if manually typing, but $webRepoPath variable itself should contain the raw path)
$webRepoPath = "https://scripts.poteez.com/ExchangeScript/Scripts/"

# Local path to store files (usually the directory where this script resides)
$localPath = $PSScriptRoot

# Version file name
$versionFileName = "version.txt"

# Manifest file name (lists all files/paths to download)
$manifestFileName = "manifest.txt"

# --- Function Definition ---

# Function to update from the web repository
function UpdateFromWebRepo {
    param(
        [Parameter(Mandatory=$true)]
        [string]$RepoPath
    )

    # --- Step 1: Fetch Central Version ---
    $centralVersionUri = "$RepoPath/$versionFileName"
    try {
        Write-Host "Attempting to fetch version file from: $centralVersionUri"
        $webRequestParams = @{
            Uri             = $centralVersionUri
            UseBasicParsing = $true # Often helps with compatibility/simplicity
            ErrorAction     = 'Stop' # Ensure catch block triggers reliably
        }
        # Ensure we get plain text content and trim whitespace
        $centralVersion = (Invoke-WebRequest @webRequestParams).Content.Trim()
        Write-Host "Central version fetched: $centralVersion"
    } catch {
        $errorMessage = $_.Exception.Message
        Write-Host ("ERROR: Could not fetch central version file '{0}'. Message: {1}" -f $versionFileName, $errorMessage)
        Write-Host "Please check the repository path and network connectivity."
        return $false # Cannot proceed without central version
    }

    # --- Step 2: Get Local Version ---
    $localVersionFilePath = Join-Path -Path $localPath -ChildPath $versionFileName
    $localVersion = Get-Content -Path $localVersionFilePath -ErrorAction SilentlyContinue
    # If file doesn't exist, $localVersion will be $null, which is fine for comparison
    Write-Host "Local version (if present): $localVersion"

    # --- Step 3: Compare Versions and Update if Needed ---
    if ($centralVersion -ne $localVersion) {
        Write-Host "Newer version ($centralVersion) found. Local version is '$localVersion'."
        Write-Host "Starting update from $RepoPath..."

        # --- Step 4: Fetch the Manifest File ---
        $filesToDownload = @() # Initialize empty array
        $manifestUri = "$RepoPath/$manifestFileName"
        try {
            Write-Host "Attempting to fetch manifest file from: $manifestUri"
            $manifestRequestParams = @{
                Uri             = $manifestUri
                UseBasicParsing = $true
                ErrorAction     = 'Stop'
            }
            # Split content into lines, remove empty lines/whitespace-only lines
            $manifestContent = (Invoke-WebRequest @manifestRequestParams).Content
            $filesToDownload = $manifestContent -split [System.Environment]::NewLine | Where-Object { $_.Trim() -ne '' }

            Write-Host "Manifest fetched successfully. Found $($filesToDownload.Count) files/paths listed."

            if ($filesToDownload.Count -eq 0) {
                Write-Host "WARNING: Manifest file '$manifestFileName' is empty or could not be parsed correctly."
                Write-Host "No files will be downloaded based on the manifest."
                # Optional: Decide if you want to force download version.txt anyway or fail completely
                # Let's attempt to download version.txt as a minimum requirement if manifest is empty
                 if (-not ($filesToDownload -contains $versionFileName)) {
                    $filesToDownload = @($versionFileName)
                    Write-Host "Attempting to download '$versionFileName' as a minimum."
                }
            }
        } catch {
            $errorMessage = $_.Exception.Message
            Write-Host ("ERROR: Could not fetch manifest file '{0}'. Message: {1}" -f $manifestFileName, $errorMessage)
            Write-Host "Update cannot proceed without the manifest file list."
            return $false # Cannot proceed without the list of files
        }

        # --- Step 5: Download Files from Manifest List ---
        $updateSuccessful = $true # Track overall success
        Write-Host "----------------------------------------"
        Write-Host "Downloading files..."
        Write-Host "----------------------------------------"

        foreach ($fileRelativePath in $filesToDownload) {
            # Trim any potential whitespace from the manifest line
            $cleanRelativePath = $fileRelativePath.Trim()
            if ([string]::IsNullOrWhiteSpace($cleanRelativePath)) { continue } # Skip if somehow an empty line got through

            # Construct remote URI (handle spaces by basic encoding)
            # Note: Assumes forward slashes '/' in manifest for subdirs.
            $encodedFileRelativePath = $cleanRelativePath -replace ' ', '%20'
            $downloadUri = "$RepoPath/$encodedFileRelativePath"

            # Construct full local path
            # Use Join-Path which handles path separators correctly for the OS
            $localFilePath = Join-Path -Path $localPath -ChildPath $cleanRelativePath

            # Ensure local directory exists before downloading
            $localDirectory = Split-Path -Path $localFilePath -Parent
            if ($localDirectory -and (-not (Test-Path -Path $localDirectory -PathType Container))) {
                Write-Host " -> Creating directory: '$localDirectory'"
                try {
                    New-Item -ItemType Directory -Path $localDirectory -Force -ErrorAction Stop | Out-Null
                    Write-Host " -> Directory created successfully."
                } catch {
                     $errorMessage = $_.Exception.Message
                     Write-Host (" -> ERROR: Failed to create directory '{0}'. Message: {1}" -f $localDirectory, $errorMessage)
                     $updateSuccessful = $false
                     Write-Host (" -> Skipping download of '{0}' due to directory creation failure." -f $cleanRelativePath)
                     continue # Skip this file if directory creation fails
                }
            }

            # Download the file
            Write-Host " -> Downloading: '$cleanRelativePath'"
            # Write-Host "    From: '$downloadUri'" # Uncomment for verbose debugging
            # Write-Host "    To:   '$localFilePath'" # Uncomment for verbose debugging
            try {
                 $downloadParams = @{
                    Uri             = $downloadUri
                    OutFile         = $localFilePath
                    UseBasicParsing = $true
                    ErrorAction     = 'Stop'
                }
                Invoke-WebRequest @downloadParams
                Write-Host " -> Downloaded '$cleanRelativePath' successfully."
            } catch {
                $errorMessage = $_.Exception.Message
                # Check for common 404 error
                if ($_.Exception.Response -ne $null -and $_.Exception.Response.StatusCode -eq 404) {
                     Write-Host (" -> ERROR: Failed to download '{0}'. File not found (404) at '{1}'." -f $cleanRelativePath, $downloadUri)
                } else {
                     Write-Host (" -> ERROR: Failed to download '{0}'. Message: {1}" -f $cleanRelativePath, $errorMessage)
                }
                $updateSuccessful = $false # Mark update as failed if any file fails
                # Consider whether to stop entirely or continue with other files (current: continue)
            }
             Write-Host "----------" # Separator between files
        } # End foreach file

        # --- Step 6: Final Status and Return ---
        Write-Host "----------------------------------------"
        if ($updateSuccessful) {
             Write-Host "Update to version $centralVersion completed successfully!"
             # CRITICAL: Update the local version file ONLY if all downloads were successful
             try {
                 Set-Content -Path $localVersionFilePath -Value $centralVersion -Encoding UTF8 -Force -ErrorAction Stop
                 Write-Host "Local version file updated to $centralVersion."
             } catch {
                 $errorMessage = $_.Exception.Message
                 Write-Host ("WARNING: Update downloads seemed successful, but failed to update local version file '{0}'. Message: {1}" -f $localVersionFilePath, $errorMessage)
                 # Decide if this should still return true or false. Returning true since files likely updated.
             }
             return $true
        } else {
             Write-Host "Update completed with one or more errors. Please review the log above."
             Write-Host "Local files may be in an inconsistent state."
             # Do NOT update the local version file if there were errors.
             return $false # Indicate partial or full failure
        }

    } else {
        Write-Host "Scripts are already up-to-date (Version: $localVersion)."
        return $false # Indicate no update was needed
    }
} # End Function UpdateFromWebRepo

# --- Main Script Execution ---

Write-Host "========================================"
Write-Host " Starting Update Process"
Write-Host " Repository: $webRepoPath"
Write-Host " Local Path: $localPath"
Write-Host "========================================"
Write-Host "" # Newline for readability

$updatePerformed = $false # Default status
try {
    $updatePerformed = UpdateFromWebRepo -RepoPath $webRepoPath
} catch {
    # Catch unexpected errors in the main call
    Write-Host "An unexpected error occurred during the update process:"
    Write-Host $_.Exception.Message
    # Consider logging $_ | Format-List * -Force for more details
    $updatePerformed = $false
}

Write-Host "" # Newline for readability
Write-Host "========================================"
if ($updatePerformed) {
    Write-Host "Update process finished. Files were updated."
} else {
    # This message covers "already up to date", "web repo unavailable", "manifest error", or "download errors"
    Write-Host "Update process finished. No updates performed or errors occurred during download."
}
Write-Host "========================================"
Write-Host ""

# Optional: Pause if running directly in a console window that might close automatically
# Read-Host -Prompt "Press Enter to continue..."

# --- End of Update Script ---
# The rest of your original batch script (`@echo off`...) would typically follow
# AFTER this PowerShell script finishes execution if called from batch.
# If this PS1 *is* the main entry point, you would launch your batch file from here if needed.
# Example: & cmd /c ".\On-Prem Exchange Script.bat"