import json
import re
from reportlab.platypus import Paragraph, Frame, Spacer
from reportlab.lib.styles import getSampleStyleSheet
import datetime
from reportlab.lib.styles import getSampleStyleSheet
import streamlit as st
import tempfile
import os
from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import A4, letter 

ENABLE_STREAM = False

def merge_json_strings(json_str1, json_str2):
    """
    Merges two JSON strings into one, handling potential markdown tags.

    Args:
        json_str1: The first JSON string, potentially with markdown tags.
        json_str2: The second JSON string, potentially with markdown tags.

    Returns:
        A cleaned JSON string representing the merged JSON objects.
    """

    # Clean the JSON strings by removing markdown tags
    cleaned_json_str1 = clean_markdown(json_str1)
    cleaned_json_str2 = clean_markdown(json_str2)

    try:
        # Parse the cleaned JSON strings into Python dictionaries
        data1 = json.loads(cleaned_json_str1)
        data2 = json.loads(cleaned_json_str2)

        # Merge the dictionaries
        merged_data = _merge_dicts(data1, data2)

        # Convert the merged dictionary back into a JSON string
        return json.dumps(merged_data, indent=2)
    except json.JSONDecodeError as e:
        return f"Error decoding JSON: {e}"
    
def clean_markdown(text):
    """
    Removes markdown tags from a string if they exist. 
    Otherwise, returns the original string unchanged.

    Args:
        text: The input string.

    Returns:
        The string with markdown tags removed, or the original string 
        if no markdown tags were found.
    """
    try:
        # Check if the string contains markdown 
        if re.match(r"^```json\s*", text) and re.search(r"\s*```$", text):
            # Remove leading ```json
            text = re.sub(r"^```json\s*", "", text) 
            # Remove trailing ```
            text = re.sub(r"\s*```$", "", text) 
        return text
    except Exception as e:
        # Log the error 
        st.error(f"Error cleaning markdown: {e}") 
        return None

def _merge_dicts(data1, data2):
    """
    Recursively merges two data structures.

    Handles merging of dictionaries and lists. 
    For dictionaries, if a key exists in both and both values are dictionaries 
    or lists, they are merged recursively. Otherwise, the value from data2 is used.
    For lists, the lists are concatenated.

    Args:
        data1: The first data structure (dictionary or list).
        data2: The second data structure (dictionary or list).

    Returns:
        The merged data structure.

    Raises:
        ValueError: If the data types are not supported for merging.
    """
    if isinstance(data1, dict) and isinstance(data2, dict):
        for key, value in data2.items():
            if key in data1 and isinstance(data1[key], (dict, list)) and isinstance(value, type(data1[key])):
                _merge_dicts(data1[key], value)
            else:
                data1[key] = value
        return data1
    elif isinstance(data1, list) and isinstance(data2, list):
        return data1 + data2
    else:
        raise ValueError("Unsupported data types for merging")

def create_json(metadata, content):
    """
    Creates a JSON string combining metadata and content.

    Args:
        metadata: A dictionary containing metadata information.
        content: A dictionary containing the quiz content.

    Returns:
        A string representing the combined JSON data.
    """

    # Create metadata with timestamp
    metadata = {
        "subject": metadata.get("subject", ""),
        "topic": metadata.get("topic", ""),
        "num_questions": metadata.get("num_questions", 0),
        "exam_type": metadata.get("exam_type", ""),
        "timestamp": datetime.datetime.now().isoformat()
    }

    # Combine metadata and content
    combined_data = {"metadata": metadata, "content": content}

    # Convert to JSON string
    json_string = json.dumps(combined_data, indent=4)

    return json_string

def create_pdf(data):
    """
    Creates a PDF file with text wrapping for quiz content, supporting multiple question types.
    """
    try:
        # Load the JSON data
        data = json.loads(data)

        if 'metadata' not in data or 'content' not in data:
            st.error("Error: Invalid data format. Missing 'metadata' or 'content' keys.")
            return None

        metadata = data['metadata']
        content = data['content']

        # Validate metadata
        required_metadata_keys = ['subject', 'topic', 'exam_type', 'num_questions']
        if not all(key in metadata for key in required_metadata_keys):
            st.error("Error: Invalid metadata format. Missing required keys.")
            return None

        # Create a unique filename with timestamp
        timestamp = datetime.datetime.now().strftime("%Y%m%d_%H%M%S")
        pdf_filename = f"quiz_output_{timestamp}.pdf"
        temp_dir = tempfile.gettempdir()
        pdf_path = os.path.join(temp_dir, pdf_filename)

        c = canvas.Canvas(pdf_path, pagesize=A4)
        c.setFont("Helvetica", 10)

        styles = getSampleStyleSheet()
        text_style = styles['Normal']

        # Starting position
        margin_left = 50
        y_position = 750
        line_height = 12  # Adjusted for tighter spacing
        frame_width = 500
        first_page = True

        def wrap_text_draw(text, x, y):
            """
            Wraps and draws text using ReportLab's Paragraph for automatic line breaks.
            """
            p = Paragraph(text, text_style)
            width, height = p.wrap(frame_width, y)
            p.drawOn(c, x, y - height)
            return height

        # Print metadata once on the first page
        if first_page:
            for key, label in [("subject", "Subject"), ("topic", "Topic"),
                                ("exam_type", "Type"), ("num_questions", "Number of Questions")]:
                c.drawString(margin_left, y_position, f"{label}: {metadata[key]}")
                y_position -= line_height
            y_position -= line_height
            first_page = False

        # Render questions and options
        for idx, q in enumerate(content):
            if not isinstance(q, dict):
                st.error(f"Error: Invalid question format at index {idx}. Skipping...")
                continue

            question_text = f"{idx + 1}. {q.get('question', q.get('statement', ''))}"
            height = wrap_text_draw(question_text, margin_left, y_position)
            y_position -= (height + line_height)

            if y_position < 50:
                c.showPage()
                c.setFont("Helvetica", 10)
                y_position = 750

            # Handle specific exam types
            exam_type = metadata['exam_type']

            if exam_type == "Multiple Choice":
                for option_idx, option in enumerate(q['options'], ord('a')):
                    option_text = f"{chr(option_idx)}) {option}"
                    height = wrap_text_draw(option_text, margin_left + 20, y_position)
                    y_position -= (height + line_height)

                    if y_position < 50:
                        c.showPage()
                        c.setFont("Helvetica", 10)
                        y_position = 750

                # Print correct answer
                correct_answer_text = f"Correct Answer: {q['correct_answer']}"
                height = wrap_text_draw(correct_answer_text, margin_left + 20, y_position)
                y_position -= (height + line_height)

            elif exam_type == "True or False":
                for option in q['options']:
                    height = wrap_text_draw(option, margin_left + 20, y_position)
                    y_position -= (height + line_height)

                    if y_position < 50:
                        c.showPage()
                        c.setFont("Helvetica", 10)
                        y_position = 750

                correct_answer_text = f"Correct Answer: {q['correct_answer']}"
                height = wrap_text_draw(correct_answer_text, margin_left + 20, y_position)
                y_position -= (height + line_height)

            elif exam_type in ["Short Response", "Essay Type"]:
                answer_text = f"Correct Answer: {q['correct_answer']}"
                height = wrap_text_draw(answer_text, margin_left + 20, y_position)
                y_position -= (height + line_height)

            if y_position < 50:
                c.showPage()
                c.setFont("Helvetica", 10)
                y_position = 750

        # Add a footer
        notice = "This exam was generated by the WVSU Exam Maker (c) 2025 West Visayas State University"
        c.drawString(margin_left, y_position, notice)

        c.save()
        return pdf_path

    except Exception as e:
        st.error(f"Error creating PDF: {e}")
        return None

def generate_quiz_content(data):
    """
    Separates the metadata and content from a JSON string containing exam data.
    Creates a markdown formatted text that contains the exam metadata and 
    enumerates the questions, options and answers nicely formatted for readability.

    Args:
      data: A JSON string containing the exam data.

    Returns:
      A markdown formatted string.
    """
    data = json.loads(data)
    metadata = data["metadata"]
    content = data["content"]
    exam_type = metadata["exam_type"]
    if exam_type == "Multiple Choice":
        md_text = f"""# {metadata['subject']} - {metadata['topic']}

**Exam Type:** {metadata['exam_type']}  
**Number of Questions:** {metadata['num_questions']}  
**Timestamp:** {metadata['timestamp']}

---

"""
        for i, q in enumerate(content):
            md_text += f"""Question {i+1}:
            {q['question']}

"""
            for j, option in enumerate(q['options'], ord('a')):
                md_text += f"""{chr(j)}. {option}  

"""
            md_text += f"""**Correct Answer:** {q['correct_answer']}

---

"""
        md_text += """This exam was generated by the WVSU Exam Maker
            (c) 2025 West Visayas State University
"""
            
    elif exam_type == "True or False":
        md_text = f"""# {metadata['subject']} - {metadata['topic']}

**Exam Type:** {metadata['exam_type']}  
**Number of Questions:** {metadata['num_questions']}  
**Timestamp:** {metadata['timestamp']}

---

"""

        for i, q in enumerate(content):
            md_text += f"""Statement {i+1}:

{q['statement']}

"""
            for j, option in enumerate(q['options'], ord('a')):
                md_text += f"""{option}  
"""

            md_text += f"""**Correct Answer:** {q['correct_answer']}

---
"""
        md_text += """This exam was generated by the WVSU Exam Maker
(c) 2025 West Visayas State University"""

    elif exam_type == "Short Response" or exam_type == "Essay Type":
        md_text = f"""# {metadata['subject']} - {metadata['topic']}

**Exam Type:** {metadata['exam_type']}  
**Number of Questions:** {metadata['num_questions']}  
**Timestamp:** {metadata['timestamp']}

---

"""

        for i, q in enumerate(content):
            md_text += f"""Question {i+1}:

{q['question']}

"""
            md_text += f"""**Correct Answer:** {q['correct_answer']}

---
"""
        md_text += """This exam was generated by the WVSU Exam Maker
(c) 2025 West Visayas State University"""

    return md_text
    
def generate_metadata(subject, topic, num_questions, exam_type):
    """Generates quiz metadata as a dictionary combining num_questions, 
    exam_type, and timestamp.

    Args:
        num_questions: The number of questions in the exam (int).
        exam_type: The type of exam (str).

    Returns:
        A dictionary containing the quiz metadata.
    """

    # Format the timestamp
    timestamp = datetime.datetime.now()
    formatted_timestamp = timestamp.strftime("%Y-%m-%d %H:%M:%S") 
    
    metadata = {
        "subject": subject,
        "topic": topic,
        "num_questions": num_questions,
        "exam_type": exam_type,
        "timestamp": formatted_timestamp
    }

    return metadata

def generate_text(prompt):
    """Generates text based on the  prompt."""
    try:
            
        # Send a text prompt to Gemini API
        chat = st.session_state.chat
        response = chat.send_message(
            [
                prompt
            ],
            stream=ENABLE_STREAM  
        )

        return response.text
   
    except Exception as e:
        st.error(f"An error occurred while generating text: {e}")
        return None