Added Text Rewriter tool

[Shreya6901]

Description

Introduces a Text Rewriter tool under app/tools/text_rewriter/ that enables users to transform input text or documents according to custom instructions—such as “Simplify for middle school,” “Paraphrase,” or “Translate to French/Spanish.” This feature mirrors the existing Notes Generator structure for consistency, leveraging get_docs for file loading and rewriting. It includes input validation, clear error handling, and comprehensive unit tests.

Related Issue

Issue #128

Type of Change

• New feature: A non-breaking change that adds functionality
• Documentation update: Changes or updates to documentation
• Test enhancement: Adding or updating tests; no production code change

Proposed Solution

1. Input Handling
   • Validates that either text or text_file_url is provided
   • Requires text_file_type when a URL is supplied, casting non-string types to trigger a controlled error
   • Uses get_docs(...) to fetch and parse CSV, PDF, DOCX, PPTX, TXT, MD, and Google-hosted PDFs
2. Rewriting Logic
   • Executor (core.py): Coordinates validation, document loading, and calls TextRewriterPipeline
   • Pipeline (tools.py):
     • If documents are loaded, concatenates their content and calls the LLM with the user instruction
     • Otherwise, invokes the LLM directly on raw text
     • Embeds rewrite_instruction and lang into the prompt template
3. Metadata & UI Discovery
   • Defined metadata.json to describe form fields for instruction, text, URL, type, and language, enabling auto-generated UIs
4. Testing
   • Added tests/test_core.py that mocks get_docs and TextRewriterPipeline.rewrite() to isolate and verify executor behavior
   • Covers valid text-only rewrites, missing-input errors, and valid/invalid file-type scenarios for each supported format

How to Test

1. Install dependencies:
pip install -r requirements.txt
2. Run the Text Rewriter tests:
PYTHONPATH=./ pytest app/tools/text_rewriter/tests/test_core.py
3. Confirm that all tests pass without warnings

Unit Tests

• test_core.py
  • test_executor_text_valid: Verifies direct-text rewriting
  • test_executor_missing_all_inputs: Checks missing-input error
  • test_executor__text_file_url_valid: Confirms success for each supported file type
  • test_executor__text_file_url_invalid: Verifies error when text_file_type is not a string

Documentation Updates

Indicate whether documentation needs to be updated due to this PR.

N/A

Checklist

• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• Any dependent changes have been merged and published in downstream modules.

Additional Information

Looking Forward to your review and feedback