fix: Expose cached AI pdf data url to webview

[kaaviya98]

Changes done

Reason for the changes

Fixes # .

[gemini-code-assist]

Summary of Changes

Hello @kaaviya98, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the application's ability to integrate local PDF content with web-based views, particularly for AI chat functionalities. It establishes a secure and efficient way for webviews to access cached PDF files by exposing their base64 encoded data URLs through a dedicated JavaScript interface. This change improves the user experience by allowing seamless display of offline PDF content within web components.

Highlights

• PDF Data Exposure to Webview: Introduced a mechanism to expose locally cached PDF data URLs to webviews, enabling web-based components to access and display these files.
• New JavaScript Interface: A CachedPdfPathProvider class was added to serve as a JavaScript interface, allowing webviews to query for cached PDF status and retrieve base64 encoded PDF data URLs.
• Fragment Integration: The AIChatPdfFragment now initializes this JavaScript interface upon webview load, and the DocumentViewerFragment passes the cached PDF path to AIChatPdfFragment.
• PDF Path Retrieval: The PDFDownloadManager was extended with a new method to easily retrieve the absolute path of a cached PDF.
• Sample Configuration Update: Updated the sample application's InstituteSettings to point to "staging.testpress.in" instead of "sandbox.testpress.in".

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[gemini-code-assist]

Code Review

This pull request aims to expose a cached PDF's data URL to a WebView for the AI chat feature. The implementation correctly passes the PDF path and uses a JavaScript interface to expose the data. However, there are a few significant issues. A critical security vulnerability is introduced by enabling broad file access for the WebView, which is unnecessary for the current implementation. Additionally, the new CachedPdfPathProvider has resource management and potential performance problems, such as not closing file streams correctly and risking OutOfMemoryError with large files. My review includes suggestions to fix these issues.

[gemini-code-assist]

Enabling allowFileAccessFromFileURLs and allowUniversalAccessFromFileURLs poses a significant security risk, especially when loading content from a remote URL. These settings could allow malicious JavaScript on the web page to access local files on the user's device.

Since the PDF data is being provided to the WebView via a JavaScript interface as a Base64-encoded data URL, direct file system access from the WebView is not necessary. Please remove these settings to enhance security.

[gemini-code-assist]

This method has a few areas for improvement:

1. Resource Handling: The FileInputStream is not guaranteed to be closed if an exception occurs during readBytes() or encodeToString(). It's safer to use the use extension function, which automatically closes the stream.
2. Exception Handling: Catching a generic Exception is too broad. It's better to catch more specific exceptions, like IOException, to handle file-related errors more precisely.
3. Memory Usage: The readBytes() function reads the entire file into a byte array in memory. This can lead to an OutOfMemoryError if the PDF file is large. While addressing this might require a larger design change, we should at least ensure resources are handled correctly.

Here's a suggested refactoring to address the resource and exception handling:

Suggested change

	fun getBase64PdfData(): String {
	return if (isPDFCached()) {
	try {
	val file = File(pdfPath)
	val inputStream = FileInputStream(file)
	val bytes = inputStream.readBytes()
	inputStream.close()
	Base64.encodeToString(bytes, Base64.DEFAULT)
	} catch (e: Exception) {
	""
	}
	} else {
	""
	}
	}
	fun getBase64PdfData(): String {
	return if (isPDFCached()) {
	try {
	File(pdfPath).inputStream().use {
	val bytes = it.readBytes()
	Base64.encodeToString(bytes, Base64.DEFAULT)
	}
	} catch (e: java.io.IOException) {
	// It's good practice to log the exception for debugging purposes.
	""
	}
	} else {
	""
	}
	}

[gemini-code-assist]

For better code clarity and to follow idiomatic Kotlin conventions, it's recommended to use isNotEmpty() instead of !pdfPath.isEmpty().

Suggested change

	fun isPDFCached(): Boolean {
	return !pdfPath.isEmpty() && File(pdfPath).exists()
	}
	fun isPDFCached(): Boolean {
	return pdfPath.isNotEmpty() && File(pdfPath).exists()
	}