$configPath = Join-Path $PSScriptRoot "config.json"

function Load-Config {
    if (Test-Path $configPath) {
        try {
            $script:config = Get-Content $configPath | ConvertFrom-Json
            $script:txtSiteUrl.Text = $config.SiteUrl
            return $true
        }
        catch {
            Write-Error "Invalid config file: $_"
            return $false
        }
    }
    return $false
}

function Save-Config {
    param(
        [string]$SiteUrl,
        [string]$ProductionLibrary,
        [string]$TempLibrary
    )
    
    $config = @{
        SiteUrl = $SiteUrl
        ProductionLibrary = $ProductionLibrary
        TempLibrary = $TempLibrary
    }
    
    $config | ConvertTo-Json | Set-Content $configPath
}

function Connect-SharePoint {
    try {
        $siteUrl = $script:txtSiteUrl.Text
        
        if (-not $siteUrl) {
            throw "Please enter a Site URL"
        }

        # Disconnect any existing connection first
        Disconnect-PnPOnline -ErrorAction SilentlyContinue
        
        # Use modern authentication with device code flow
        Connect-PnPOnline -Url $siteUrl -Interactive -ForceAuthentication `
            -ErrorAction Stop `
            -WarningAction SilentlyContinue
        
        # Verify connection
        $web = Get-PnPWeb -ErrorAction Stop
        if (-not $web) {
            throw "Failed to connect to SharePoint site"
        }
        
        return $true
    }
    catch {
        $script:txtStatus.Text += "Connection Error: $($_.Exception.Message)`n"
        return $false
    }
}

function List-XlsFiles {
    if (-not (Connect-SharePoint)) {
        return
    }
    
    $folderPath = $script:txtFolder.Text
    $query = "<View Scope='RecursiveAll'><Query><Where>
        <And>
            <Contains><FieldRef Name='FileRef'/><Value Type='Text'>.xls</Value></Contains>
            <Not><Contains><FieldRef Name='FileRef'/><Value Type='Text'>.xlsx</Value></Contains></Not>
        </And>
    </Where></Query></View>"

    $items = Get-PnPListItem -List $script:txtProdLib.Text -PageSize 2000 -Query $query
    
    if (-not [string]::IsNullOrWhiteSpace($folderPath)) {
        $folderFilter = "*$($folderPath.Replace('\','/'))*"
        $items = $items | Where { $_.FieldValues.FileRef -like $folderFilter }
    }
    
    foreach ($item in $items) {
        $fileList += [PSCustomObject]@{
            OriginalPath = $item.FieldValues.FileRef
            TempPath = "$($script:txtTempLib.Text)/$($item.FieldValues.FileLeafRef)"
        }
    }
    
    $fileList | ConvertTo-Json | Set-PnPFileContent -Folder $tempLibrary -FileName "FileList.json"
    $script:txtStatus.Text += "Found $($fileList.Count) XLS files`n"
}

function Convert-Files {
    if (-not (Connect-SharePoint -SiteUrl "https://yoursite.sharepoint.com")) {
        return
    }
    
    $excel = New-Object -ComObject Excel.Application
    $excel.Visible = $false
    
    try {
        Get-PnPFile -Url "/sites/yoursite/$($script:txtTempLib.Text)/FileList.json" -Path $env:TEMP -Filename "FileList.json"
        $files = Get-Content "$env:TEMP\FileList.json" | ConvertFrom-Json
        
        foreach ($file in $files) {
            try {
                $workbook = $excel.Workbooks.Open((Convert-PnPFile -Url $file.OriginalPath -Path $env:TEMP -Filename $file.OriginalFileName))
                $newName = [System.IO.Path]::ChangeExtension($file.OriginalFileName, ".xlsx")
                $workbook.SaveAs([System.IO.Path]::Combine($env:TEMP, $newName), 51) # 51 = xlsx
                Add-PnPFile -Folder "Documents" -Path "$env:TEMP\$newName"
                $script:txtStatus.Text += "Converted $($file.OriginalFileName) to XLSX`n"
            }
            finally {
                $workbook.Close()
            }
        }
    }
    finally {
        $excel.Quit()
    }
}

function Move-Files {
    if (-not (Connect-SharePoint -SiteUrl "https://yoursite.sharepoint.com")) {
        return
    }
    
    $files = Get-Content "$env:TEMP\FileList.json" | ConvertFrom-Json
    
    foreach ($file in $files) {
        Move-PnPFile -SourceUrl $file.OriginalPath -TargetUrl $file.TempPath -Force
        $xlsxPath = [System.IO.Path]::ChangeExtension($file.OriginalPath, ".xlsx")
        Move-PnPFile -SourceUrl "$($script:txtProdLib.Text)/$xlsxPath" -TargetUrl $xlsxPath -Force
        $script:txtStatus.Text += "Moved $($file.OriginalFileName) and its XLSX version`n"
    }
}
function Get-FolderBrowser {
    try {
        # Verify library exists and is accessible
        $library = Get-PnPList -Identity $script:txtProdLib.Text -Includes RootFolder,HasUniqueRoleAssignments
        if ($library.HasUniqueRoleAssignments) {
            throw "This library has unique permissions - verify app has access"
        }
        
        # Get folders with elevated permissions
        $ctx = Get-PnPContext
        $ctx.Load($library.RootFolder.Folders)
        $ctx.ExecuteQuery()
        
        return $library.RootFolder.Folders | 
            Select-Object Name, ServerRelativeUrl |
            Out-GridView -Title "Select Folder" -PassThru
    }
    catch {
        $script:txtStatus.Text += "Folder Error: $($_.Exception.Message)`n"
        return $null
    }
}