"""
Acknowledgement:
The Smart Context Citation (SCC) system was developed by Dr. Majed Abuseif. 
The text fragments scroll functionality in the HTML environment is based on Burris and Bokan (2023). 
Conceptualisation, primary coding, integration, project management, and finalisation were undertaken by Dr. Majed Abuseif. 
Project planning, execution plan, and review were conducted by Dr. Majed Abuseif in collaboration with ChatGPT. 
Formatting and design were contributed by Dr. Majed Abuseif and Manus. 
Programming contributions were provided by Dr. Majed Abuseif and Grok, with hosting on Hugging Face. 
The code is implemented in Python.
"""

import streamlit as st
import hashlib
import urllib.parse
from datetime import datetime
import pytz
import re
import pandas as pd
import base64
import io
import openpyxl
from openpyxl.utils.dataframe import dataframe_to_rows
from openpyxl.worksheet.hyperlink import Hyperlink

# --- Constants ---
MELBOURNE_TIMEZONE = 'Australia/Melbourne'

# --- Custom CSS for simplified UI ---
def load_css():
    st.markdown("""
    <style>
    .main-header {
        padding: 0.5rem 0;
        text-align: center;
        margin: 0.5rem 0;
    }
    
    .citation-output {
        background: #f8f8f8;
        border: 1px solid #e0e0e0;
        border-radius: 4px;
        padding: 1rem;
        margin: 1rem 0;
        font-family: 'Courier New', monospace;
    }
    
    .warning-box {
        background: #fff3f3;
        border: 1px solid #e0e0e0;
        border-radius: 4px;
        padding: 1rem;
        margin: 1rem 0;
        color: #d32f2f;
    }
    
    .success-box {
        background: #e8f5e9;
        border: 1px solid #e0e0e0;
        border-radius: 4px;
        padding: 1rem;
        margin: 1rem 0;
        color: #2e7d32;
    }
    
    .info-card {
        background: white;
        border-radius: 4px;
        padding: 1rem;
        margin: 0.5rem 0;
        border-left: 1px solid #e0e0e0;
    }
    
    .footer {
        text-align: center;
        padding: 1rem;
        margin-top: 1rem;
        border-top: 1px solid #e0e0e0;
        font-size: 0.9rem;
    }
    
    .hash-display {
        background: #f8f8f8;
        border: 1px solid #e0e0e0;
        border-radius: 4px;
        padding: 1rem;
        font-family: 'Courier New', monospace;
        font-size: 0.85rem;
        word-break: break-all;
        margin: 0.5rem 0;
    }
    
    .tab-content {
        padding: 0.5rem 0;
    }
    
    .datetime-display {
        background: #f8f8f8;
        border-radius: 4px;
        padding: 0.8rem;
        margin: 0.5rem 0;
        border-left: 1px solid #e0e0e0;
        font-family: 'Courier New', monospace;
        font-size: 1rem;
    }
    
    .rendered-citation {
        margin: 0.5rem 0;
        font-size: 1.4rem;
    }
    
    .citation-table {
        margin: 1rem 0;
        width: 100%;
        border-collapse: collapse;
    }
    
    .citation-table th, .citation-table td {
        border: 1px solid #e0e0e0;
        padding: 0.5rem;
        text-align: left;
    }
    
    .citation-table th {
        background: #f8f8f8;
        font-weight: bold;
    }
    
    .citation-table th:nth-child(7), .citation-table td:nth-child(7) { /* Annotated Text column */
        width: 30%; /* Match SCC Index width */
    }
    
    .citation-table th:nth-child(6), .citation-table td:nth-child(6) { /* SCC Index column */
        width: 30%;
    }
    </style>
    """, unsafe_allow_html=True)

# --- Helper Functions ---
def select_longest_segment(text):
    # Split text by various dashes (hyphen, non-breaking hyphen, en dash, em dash)
    dash_variants = ['\u002D', '\u2011', '\u2013', '\u2014']
    segments = [text]
    for dash in dash_variants:
        new_segments = []
        for segment in segments:
            new_segments.extend(segment.split(dash))
        segments = new_segments
    # Return the longest segment, or original text if no dashes
    return max(segments, key=len, default=text).strip()

def encode_text_fragment(text):
    # Encode text for W3C Text Fragments, preserving only regular hyphens (U+002D)
    # Non-breaking hyphens (U+2011) are encoded as %E2%80%91
    # En dashes (U+2013) are encoded as %E2%80%93
    # Em dashes (U+2014) are encoded as %E2%80%94
    return urllib.parse.quote(text, safe='-')

def generate_citation_hash(author, year, url, fragment_text, cited_text, username, task_name, current_date, current_time):
    # Normalize inputs by stripping whitespace
    fragment_text = select_longest_segment(fragment_text.strip())
    cited_text = select_longest_segment(cited_text.strip())
    task_name = task_name.strip()
    author = author.strip()
    url = url.strip()
    username = username.strip()
    data = f"{author}, {year} | {url} | {fragment_text} | {cited_text} | {username} | {task_name} | {current_date} | {current_time}"
    return hashlib.sha256(data.encode('utf-8')).hexdigest()

def format_citation_html(url, fragment_text, author, year, scc_hash):
    # Select the longest segment for the text fragment to avoid breaking the link
    selected_fragment = select_longest_segment(fragment_text)
    encoded_fragment = encode_text_fragment(selected_fragment)
    full_url = f"{url}#:~:text={encoded_fragment}"
    return f'<a href="{full_url}" data-hash="{scc_hash}">{author} ({year})</a>'

def format_citation_end_html(url, fragment_text, author, year, scc_hash):
    # Select the longest segment for the text fragment to avoid breaking the link
    selected_fragment = select_longest_segment(fragment_text)
    encoded_fragment = encode_text_fragment(selected_fragment)
    full_url = f"{url}#:~:text={encoded_fragment}"
    return f'<a href="{full_url}" data-hash="{scc_hash}">({author}, {year})</a>'

def format_metadata_html(url, author, year, scc_hash, username, task_name, current_date, current_time):
    # Use original task_name with em dashes for text fragment URL
    metadata = f"{username}—{task_name}—{current_date}—{current_time}"
    encoded_metadata = encode_text_fragment(metadata)
    full_url = f"{url}#:~:text={encoded_metadata}"
    return f'<a href="{full_url}" data-hash="{scc_hash}">{author} ({year}). {scc_hash}</a>'

def check_for_fragment(url):
    return '#:~:text=' in url or '?utm_source=' in url

def parse_citation_text(citation_text):
    match = re.match(r'^(?:(\w[\w\s.,&et al]+)\s*\((\d{4})\)|\((\w[\w\s.,&et al]+),\s*(\d{4})\))$', citation_text.strip())
    if match:
        author = match.group(1) or match.group(3)
        year = match.group(2) or match.group(4)
        author = author.strip()
        return author, year
    return None, None

def parse_url(url):
    if not url:
        return None, None
    try:
        match = re.search(r'#:~:text=([^&]+)', url)
        fragment_text = urllib.parse.unquote(match.group(1)) if match else None
        base_url = url.split('#')[0]
        return base_url, fragment_text
    except:
        return None, None

def parse_hash_text(hash_text):
    match = re.match(r'.*?\(\d{4}\)\.\s*([0-9a-f]{64})', hash_text.strip())
    if match:
        return match.group(1)
    return None

def parse_metadata(fragment_text):
    if not fragment_text:
        return None, None, None, None
    try:
        metadata_parts = fragment_text.split('—')
        if len(metadata_parts) == 4:
            username, task_name, date, time = metadata_parts
            return username, task_name, date, time
        return None, None, None, None
    except:
        return None, None, None, None

def get_table_download_link(df, filename="citation_data.csv"):
    csv = df.to_csv(index=False)
    b64 = base64.b64encode(csv.encode()).decode()
    href = f'<a href="data:file/csv;base64,{b64}" download="{filename}">Download Citation Data as CSV</a>'
    return href

def get_excel_download_link(df, filename="citation_data.xlsx"):
    output = io.BytesIO()
    wb = openpyxl.Workbook()
    ws = wb.active
    # Write headers
    headers = df.columns.tolist()
    ws.append(headers)

    # Write data rows
    for index, row in df.iterrows():
        row_data = []
        cell_positions = {}  # track cell positions for hyperlink assignment
        urls = {}            # store URLs per column

        for col_idx, col in enumerate(headers):
            value = row[col]
            if col in ["Citation (Start of Text)", "Citation (End of Text)", "SCC Index"]:
                # Extract URL and display text from HTML anchor tag
                match = re.search(r'<a href="([^"]+)"[^>]*>([^<]+)</a>', str(value))
                if match:
                    link_url, display_text = match.groups()
                    row_data.append(display_text)
                    # Position where this cell will be written (next row after append)
                    cell_positions[col] = (ws.max_row + 1, col_idx + 1)
                    urls[col] = link_url
                else:
                    row_data.append(value)
            else:
                row_data.append(value)

        ws.append(row_data)

        # Apply hyperlinks after appending row
        for col, (r, c) in cell_positions.items():
            cell = ws.cell(row=r, column=c)
            cell.hyperlink = urls[col]
            cell.hyperlink.tooltip = "Click to visit source"
            cell.style = "Hyperlink"

    wb.save(output)
    b64 = base64.b64encode(output.getvalue()).decode()
    href = f'<a href="data:application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;base64,{b64}" download="{filename}">Download citation data as Excel</a>'
    return href

# --- Streamlit App ---
st.set_page_config(layout="wide", page_title="ISNAD")

# Load custom CSS
load_css()

# Main header
st.markdown("""
<div class="main-header">
    <h1>ISNAD</h1>
    <h3 style="font-style: italic; font-weight: normal; font-size: 1.2rem;">Integrated System for Networked Attribution & Documentation</h3>
    <h4>Piloting Stages 1: Smart Context Citation (SCC)</h4>
</div>
""", unsafe_allow_html=True)

# Expandable section for About ISNAD and Example Citation
with st.expander("About ISNAD and Example Citation"):
    st.markdown("""
    <div class="info-card">
        <p>The Integrated System for Networked Attribution & Documentation (ISNAD) is a five-layer framework designed to secure, contextualise, and verify knowledge in the era of Generative AI. It draws inspiration from the classical isnad (chains of transmission), modern referencing systems, and the Swiss Cheese Model of layered protection.</p>
        <p>The current app pilots Stages 1 of ISNAD, implemented as the Smart Context Citation (SCC) system. SCC is the first operational layer of ISNAD, focused on creating verifiable, transparent, and context-rich citations. It ensures that knowledge attribution remains trustworthy and resistant to AI tampering.</p>
        <h4>Key Features of SCC (Stage 1 of ISNAD):</h4>
        <ul>
            <li><strong>Inline Citations:</strong> Author-year citations hyperlinked to the exact text fragment in the source.</li>
            <li><strong>Authenticated Citation Identifier (ACI):</strong> A cryptographic hash that secures citation integrity.</li>
            <li><strong>SCC Index:</strong> A replacement for traditional reference lists, with verifiable links and metadata (user, task, date, time).</li>
        </ul>
        <h4>Future Layers of ISNAD (Under Development):</h4>
        <ul>
            <li>Automated citation authentication workflows.</li>
            <li>Integration with writing platforms (e.g., MS Office).</li>
            <li>Linkage with digital libraries and source databases.</li>
            <li>Printable document option with preferred traditional referencing style (e.g., APA, Harvard), allowing citations to be automatically converted for easier reading in printed documents.</li>
            <li>AI-resilient verification pipelines to protect academic outputs at scale.</li>
        </ul>
        <h4>Technical Legitimacy</h4>
        The SCC style uses the W3C Text Fragments specification by <a href="https://wicg.github.io/scroll-to-text-fragment/#:~:text=Editors%3A" target="_blank">Burris and Bokan (2023)</a> to enable precise linking to specific sections of digital content. This ensures that citations are contextually accurate, verifiable, and aligned with modern digital standards.
        <h4>Acknowledgement</h4>
        Smart Context Citation (SCC) developed by Dr. Majed Abuseif, with contributions from ChatGPT, Manus-AI, and Grok, hosted on Hugging Face.
         <h4>Example Citation</h4>
        <p><strong>Inputs:</strong></p>
        <ul>
            <li><strong>Username:</strong> Majed</li>
            <li><strong>Task Name:</strong> Design Strategies for Trees on Buildings</li>
            <li><strong>Author:</strong> Abuseif et al.</li>
            <li><strong>Year:</strong> 2023</li>
            <li><strong>URL:</strong> https://www.sciencedirect.com/science/article/pii/S2772411523000046</li>
            <li><strong>Annotated Text:</strong> Fig. 3. A proposed design framework for green roof settings in general and trees on buildings in particular. The framework consists of four categories that are required to be followed in order from outside to inside.</li>
        </ul>
        <p><strong>Outputs:</strong></p>
        <ul>
            <li><strong>Citation (Start of Text):</strong> <span style="font-size: 1.2rem;"><a href="https://www.sciencedirect.com/science/article/pii/S2772411523000046#:~:text=Fig.%203.%20A%20proposed%20design%20framework%20for%20green%20roof%20settings%20in%20general%20and%20trees%20on%20buildings%20in%20particular.%20The%20framework%20consists%20of%20four%20categories%20that%20are%20required%20to%20be%20followed%20in%20order%20from%20outside%20to%20inside.">Abuseif et al. (2023)</a></span></li>
            <li><strong>Citation (End of Text):</strong> <span style="font-size: 1.2rem;"><a href="https://www.sciencedirect.com/science/article/pii/S2772411523000046#:~:text=Fig.%203.%20A%20proposed%20design%20framework%20for%20green%20roof%20settings%20in%20general%20and%20trees%20on%20buildings%20in%20particular.%20The%20framework%20consists%20of%20four%20categories%20that%20are%20required%20to%20be%20followed%20in%20order%20from%20outside%20to%20inside.">(Abuseif et al., 2023)</a></span></li>
            <li><strong>SCC Index:</strong> <span style="font-size: 0.85rem;"><a href="https://www.sciencedirect.com/science/article/pii/S2772411523000046#:~:text=Majed%E2%80%94Design%20Strategies%20for%20Trees%20on%20Buildings%E2%80%942025-08-07%E2%80%9422%3A53%3A15">Abuseif et al. (2023). dd344cfa83eeaec090c1b957900af960a2ea9993eef6a3fc1aca2d9881a03ea4</a></span></li>
        </ul>
    </div>
    """, unsafe_allow_html=True)

# Expandable section for SCC Style Guidelines
with st.expander("SCC Style Guidelines"):
    st.markdown("""
    <div class="info-card">
        <p>The Smart Context Citation (SCC) style ensures accurate, transparent, and verifiable citations. Follow these steps to generate and verify citations using the SCC Tool.</p>
        <h4>Generating Citations</h4>
        <ol>
            <li><strong>Access the Tool:</strong> Open the &quot;Citation Generator&quot; tab.</li>
            <li><strong>Enter User Information:</strong>
                <ul>
                    <li><strong>Username:</strong> Your unique identifier (e.g., Majed).</li>
                    <li><strong>Task Name:</strong> The project or assignment name (e.g., Design Strategies for Trees on Buildings).</li>
                </ul>
            </li>
            <li><strong>Enter Citation Information:</strong>
                <ul>
                    <li><strong>Author(s) Name:</strong> The author(s) of the source (e.g., Abuseif et al.).</li>
                    <li><strong>Publication Year:</strong> The year of publication (e.g., 2023).</li>
                    <li><strong>Source URL:</strong> The full URL of the source, without text fragments (e.g., https://www.sciencedirect.com/science/article/pii/S2772411523000046).</li>
                    <li><strong>Annotated Text:</strong> The sentence or paragraph containing the information you are referencing from the source (e.g., A proposed design framework for green roof settings in general and trees on buildings in particular). Limited to 100 words to ensure reasonable processing.</li>
                </ul>
            </li>
            <li><strong>Generate Citation:</strong> Click the &quot;Generate Citation&quot; button.</li>
            <li><strong>Copy Outputs:</strong>
                <ul>
                    <li><strong>Citation (Start of Text):</strong> Use &quot;Author (Year)&quot; for the start of a sentence (e.g., Abuseif et al. (2023)).</li>
                    <li><strong>Citation (End of Text):</strong> Use &quot;(Author, Year)&quot; for in-text citations (e.g., (Abuseif et al., 2023)).</li>
                    <li><strong>SCC Index:</strong> Copy the index link (e.g., Abuseif et al. (2023). cda7ba19e51e430107e58696758fdf79b8f016d8f27e8f8691ad713e7c8bc668) for verification.</li>
                    <li>If you would like to test the reference before using it, click on it to check whether it is suitable and captures the information you need.</li>
                </ul>
            </li>
        </ol>
        <h4>Using References and the SCC Index in Your Document</h4>
        <ol>
            <li>Paste the reference directly in the appropriate place within your document.</li>
            <li>Create an SCC Index (instead of a traditional reference list), and paste the corresponding SCC Index entry for each reference you’ve used.</li>
            <li>You can download the citation table to facilitate reference tracking for your study and research. You may also submit it as an appendix with your work.</li>
        </ol>
        <h4>Verifying Citations (for Markers and Reviewers)</h4>
        <ol>
            <li><strong>Access the Tool:</strong> Open the &quot;Verify Citation&quot; tab, which provides two options for verification: Manual Verification or Excel Upload Verification (automated using the citation table).</li>
            <li><strong>Manual Verification:</strong>
                <ul>
                    <li><strong>Enter Citation Information:</strong>
                        <ul>
                            <li><strong>Citation Text:</strong> Paste the citation text (e.g., Abuseif et al. (2023) or (Abuseif et al., 2023)).</li>
                            <li><strong>Citation URL:</strong> Paste the hyperlink URL from the citation (right-click and select &quot;Copy Link Address&quot;).</li>
                        </ul>
                    </li>
                    <li><strong>Enter SCC Index Information:</strong>
                        <ul>
                            <li><strong>SCC Index Text:</strong> Paste the index text (e.g., Abuseif et al. (2023). cda7ba19e51e430107e58696758fdf79b8f016d8f27e8f8691ad713e7c8bc668).</li>
                            <li><strong>SCC Index URL:</strong> Paste the hyperlink URL from the index (right-click and select &quot;Copy Link Address&quot;).</li>
                        </ul>
                    </li>
                    <li><strong>Verify Citation:</strong> Click the &quot;Verify Citation&quot; button in the Manual Verification tab.</li>
                    <li><strong>Review Result:</strong>
                        <ul>
                            <li><strong>Authentic Citation:</strong> Displayed in green if the hash matches, confirming integrity.</li>
                            <li><strong>Unauthentic Citation:</strong> Displayed in red if the hash does not match, indicating potential tampering.</li>
                        </ul>
                    </li>
                </ul>
            </li>
            <li><strong>Automated Verification Using Citation Table:</strong>
                <ul>
                    <li><strong>Upload Excel File:</strong> In the Excel Upload Verification tab, upload the Excel file generated from the Citation Generator tab.</li>
                    <li><strong>Verify Citations:</strong> Click the &quot;Verify Citations from Excel&quot; button.</li>
                    <li><strong>Review Results:</strong> View the verification results in a table, with each citation marked as:
                        <ul>
                            <li><strong>Authenticated:</strong> If the hash matches, confirming integrity.</li>
                            <li><strong>Unauthenticated:</strong> If the hash does not match, indicating potential issues.</li>
                        </ul>
                    </li>
                </ul>
            </li>
        </ol>
    </div>
    """, unsafe_allow_html=True)

# Tabs for Citation Generator and Verify Citation
tabs = st.tabs(["Citation Generator", "Verify Citation"])

# --- Citation Generator Tab ---
with tabs[0]:
    st.markdown('<div class="tab-content">', unsafe_allow_html=True)
    
    # User Information
    st.subheader("User Information")
    col_user1, col_user2 = st.columns(2)
    with col_user1:
        username = st.text_input("Username", help="Enter your username", placeholder="e.g., Majed")
    with col_user2:
        task_name = st.text_input("Task Name", help="Enter the project or assignment name", placeholder="e.g., Design Strategies for Trees on Buildings")
    
    # Citation Information
    st.subheader("Citation Information")
    col_citation1, col_citation2 = st.columns(2)
    with col_citation1:
        author_name = st.text_input("Author(s) Name", help="Enter the author(s) name", placeholder="e.g., Abuseif et al.")
        publication_year = st.text_input("Publication Year", help="Enter the publication year", placeholder="e.g., 2023")
        source_url = st.text_input("Source URL", help="Enter the full URL of the source (without text fragments)", placeholder="e.g., https://www.sciencedirect.com/science/article/pii/S2772411523000046")
    with col_citation2:
        annotated_text = st.text_area("Annotated Text", help="Enter the sentence or paragraph containing the referenced information (maximum 100 words)", placeholder="e.g., A proposed design framework for green roof settings...", height=150)
    
    # Generate Citation Button
    generate_button = st.button("Generate Citation", type="primary", use_container_width=True)
    
    if generate_button:
        # Validate inputs
        if not all([username, task_name, author_name, publication_year, source_url, annotated_text]):
            st.error("Please fill in all fields before generating a citation.")
        elif not re.match(r'https?://[^\s]+', source_url):
            st.error("Please enter a valid URL starting with http:// or https://")
        elif not re.match(r'^\d{4}$', publication_year):
            st.error("Please enter a valid 4-digit publication year.")
        elif check_for_fragment(source_url):
            st.error("It appears you have accessed this link through an AI assistant, such as an AI overview or generative AI writing tool. To ensure academic integrity, please return to the original source and review it carefully before incorporating it into your work. Additionally, consider exploring other relevant sources to deepen your understanding of the topic.")
        else:
            # Check word count for Annotated Text
            word_count = len(annotated_text.split())
            if word_count > 100:
                st.error("Annotated Text exceeds the maximum limit of 100 words. Please reduce the text.")
            else:
                # Get current date and time in Melbourne timezone
                melbourne_tz = pytz.timezone(MELBOURNE_TIMEZONE)
                current_time = datetime.now(melbourne_tz).strftime("%H:%M:%S")
                current_date = datetime.now(melbourne_tz).strftime("%Y-%m-%d")
                
                # Generate citation hash
                scc_hash = generate_citation_hash(
                    author_name, publication_year, source_url, annotated_text, annotated_text,
                    username, task_name, current_date, current_time
                )
                
                # Generate HTML citations
                citation_link_start = format_citation_html(source_url, annotated_text, author_name, publication_year, scc_hash)
                citation_link_end = format_citation_end_html(source_url, annotated_text, author_name, publication_year, scc_hash)
                metadata_link = format_metadata_html(source_url, author_name, publication_year, scc_hash, username, task_name, current_date, current_time)
                
                # --- Persistent Table with Clickable SCC Hash ---
                
                # First, ensure session state is initialized for the citation DataFrame
                if 'citation_df' not in st.session_state:
                    st.session_state.citation_df = pd.DataFrame(columns=[
                        "Username", "Task Name", "Time", "Date", "URL",
                        "Citation (Start of Text)", "Citation (End of Text)", "SCC Index", "Annotated Text"
                    ])
                
                # Create clickable HTML for SCC Index (full metadata link)
                clickable_index = metadata_link
                
                # Create new row data
                new_row = {
                    "Username": username,
                    "Task Name": task_name,
                    "Time": current_time,
                    "Date": current_date,
                    "URL": source_url,
                    "Citation (Start of Text)": citation_link_start,
                    "Citation (End of Text)": citation_link_end,
                    "SCC Index": clickable_index,
                    "Annotated Text": annotated_text
                }
                
                # Append the new row to the session state DataFrame
                new_df = pd.DataFrame([new_row])
                st.session_state.citation_df = pd.concat([st.session_state.citation_df, new_df], ignore_index=True)
                
                # Get the accumulated DataFrame for display and download
                df = st.session_state.citation_df
                
                col_html1, col_html2 = st.columns(2)
                
                # HTML Citation - Start of Text
                with col_html1:
                    st.markdown("### Citation (Start of Text)")
                    st.markdown('<div class="rendered-citation">', unsafe_allow_html=True)
                    st.markdown(citation_link_start, unsafe_allow_html=True)
                    st.markdown('</div>', unsafe_allow_html=True)
                
                # HTML Citation - End of Text
                with col_html2:
                    st.markdown("### Citation (End of Text)")
                    st.markdown('<div class="rendered-citation">', unsafe_allow_html=True)
                    st.markdown(citation_link_end, unsafe_allow_html=True)
                    st.markdown('</div>', unsafe_allow_html=True)
                
                # SCC Index
                st.markdown("### SCC Index")
                st.markdown(metadata_link, unsafe_allow_html=True)
                
                # Display table after SCC Index
                st.markdown("### Citation Table")
                st.markdown(get_excel_download_link(df, "citation_data.xlsx"), unsafe_allow_html=True, help="New feature to help you track your citations data. Please make sure to click on the 'Enable Editing' message at the top of the file when you open it in Excel to be able to click and copy the hyperlinked citations correctly.")
                # Display table with original columns
                display_df = df[["Username", "Task Name", "Time", "Date", "Citation (Start of Text)", "SCC Index", "Annotated Text"]]
                st.markdown(display_df.to_html(classes="citation-table", index=False, escape=False), unsafe_allow_html=True)
            
            st.markdown('</div>', unsafe_allow_html=True)

# --- Verify Citation Tab ---
with tabs[1]:
    st.markdown('<div class="tab-content">', unsafe_allow_html=True)
    verify_tabs = st.tabs(["Manual Verification", "Excel Upload Verification"])
    
    with verify_tabs[0]:
        st.subheader("Citation Information")
        citation_text = st.text_input("Citation Text", help="Paste the citation text, e.g., 'Abuseif et al. (2023)' or '(Abuseif et al., 2023)'", placeholder="e.g., Abuseif et al. (2023)", key="manual_citation_text")
        citation_url = st.text_input("Citation URL", help="Paste the hyperlink URL from the citation, e.g., 'https://www.sciencedirect.com/science/article/pii/S2772411523000046#:~:text=fragment'", placeholder="e.g., https://www.sciencedirect.com/science/article/pii/S2772411523000046#:~:text=fragment", key="manual_citation_url")
        
        st.subheader("SCC Index")
        hash_text = st.text_input("SCC Index Text", help="Paste the index text, e.g., 'Abuseif et al. (2023). <hash>'", placeholder="e.g., Abuseif et al. (2023). <hash>", key="manual_hash_text")
        hash_url = st.text_input("SCC Index URL", help="Paste the hyperlink URL from the index, e.g., 'https://www.sciencedirect.com/science/article/pii/S2772411523000046#:~:text=metadata'", placeholder="e.g., https://www.sciencedirect.com/science/article/pii/S2772411523000046#:~:text=metadata", key="manual_hash_url")
        
        verify_button = st.button("Verify Citation", type="primary", use_container_width=True, key="manual_verify_button")
        
        if verify_button:
            if not all([citation_text, citation_url, hash_text, hash_url]):
                st.error("Please provide all fields (citation text, citation URL, SCC index text, SCC index URL) before verifying.")
            else:
                # Parse citation text
                author, year = parse_citation_text(citation_text)
                # Parse citation URL
                citation_base_url, citation_fragment = parse_url(citation_url)
                # Parse hash text
                scc_hash = parse_hash_text(hash_text)
                # Parse hash URL
                hash_base_url, hash_fragment = parse_url(hash_url)
                # Parse metadata from hash URL fragment
                username, task_name, date, time = parse_metadata(hash_fragment)
                
                if not all([author, year, citation_base_url, citation_fragment, scc_hash, hash_base_url, username, task_name, date, time]):
                    st.error("Invalid input format. Ensure the citation text, URLs, and SCC index text are correctly pasted from the generated output.")
                elif citation_base_url != hash_base_url:
                    st.error("The citation URL and SCC index URL must point to the same base URL.")
                else:
                    # Normalize inputs by stripping whitespace
                    citation_fragment = citation_fragment.strip()
                    task_name = task_name.strip()
                    # Check for potential truncation
                    if len(citation_fragment) < 20:
                        st.markdown("""
                        <div class="warning-box">
                            <strong>Warning:</strong> The citation text fragment may be truncated, which could cause verification to fail.
                        </div>
                        """, unsafe_allow_html=True)
                    selected_citation_fragment = select_longest_segment(citation_fragment)
                    # Recompute hash
                    recomputed_hash = generate_citation_hash(
                        author, year, citation_base_url, selected_citation_fragment, selected_citation_fragment,
                        username, task_name, date, time
                    )
                    
                    if recomputed_hash == scc_hash:
                        st.markdown("""
                        <div class="success-box">
                            <strong>Authentic citation!</strong>
                        </div>
                        """, unsafe_allow_html=True)
                            
                        # Create DataFrame for citation details
                        citation_data = {
                            "Username": [username],
                            "Task Name": [task_name],
                            "Time": [time],
                            "Date": [date],
                            "URL": [citation_base_url],
                            "Author(s) Name": [author],
                            "Year": [year],
                            "Annotated Text": [citation_fragment]
                        }
                        df = pd.DataFrame(citation_data)
                            
                        # Display table
                        st.markdown("### Citations Details")
                        st.markdown(df.to_html(classes="citations-table", index=False), unsafe_allow_html=True)
                            
                        # Provide download link
                        st.markdown(get_table_download_link(df), unsafe_allow_html=True)
                    else:
                        st.markdown("""
                        <div class="warning-box">
                            <strong>Unauthentic citation</strong>
                        </div>
                        """, unsafe_allow_html=True)
    
    with verify_tabs[1]:
        st.subheader("Upload Excel File")
        uploaded_file = st.file_uploader("Choose an Excel file", type=["xlsx"], help="Upload the Excel file containing citation data (generated from the Citation Generator tab).")
        
        verify_excel_button = st.button("Verify Citations from Excel", type="primary", use_container_width=True, key="excel_verify_button")
        
        if verify_excel_button:
            if not uploaded_file:
                st.error("Please upload an Excel file before verifying.")
            else:
                try:
                    # Read Excel file with pandas
                    df = pd.read_excel(uploaded_file)
                    expected_columns = ["Username", "Task Name", "Time", "Date", "URL", "Citation (Start of Text)", "Citation (End of Text)", "SCC Index", "Annotated Text"]
                    if not all(col in df.columns for col in expected_columns):
                        st.error("The uploaded Excel file does not contain the required columns: " + ", ".join(expected_columns))
                    else:
                        results = []
                        # Iterate over rows with data
                        for row_idx in range(len(df)):
                            row = df.iloc[row_idx]
                            # Extract text data directly
                            username = str(row["Username"]) if pd.notna(row["Username"]) else ""
                            task_name = str(row["Task Name"]) if pd.notna(row["Task Name"]) else ""
                            time = str(row["Time"]) if pd.notna(row["Time"]) else ""
                            date = str(row["Date"]) if pd.notna(row["Date"]) else ""
                            base_url = str(row["URL"]) if pd.notna(row["URL"]) else ""
                            annotated_text = str(row["Annotated Text"]) if pd.notna(row["Annotated Text"]) else ""
                            citation_start_text = str(row["Citation (Start of Text)"]) if pd.notna(row["Citation (Start of Text)"]) else ""
                            citation_end_text = str(row["Citation (End of Text)"]) if pd.notna(row["Citation (End of Text)"]) else ""
                            hash_text = str(row["SCC Index"]) if pd.notna(row["SCC Index"]) else ""
                            
                            # Initialize variables for verification
                            status = "Unauthenticated"
                            author = year = scc_hash = None
                            
                            # Perform verification using either Citation (Start of Text) or Citation (End of Text)
                            citation_text = citation_start_text or citation_end_text
                            
                            if all([citation_text, hash_text, base_url, annotated_text, username, task_name, date, time]):
                                # Parse citation text for author and year
                                author, year = parse_citation_text(citation_text)
                                # Parse hash from SCC Index text
                                scc_hash = parse_hash_text(hash_text)
                                
                                if all([author, year, scc_hash]):
                                    # Use Annotated Text as citation fragment
                                    citation_fragment = annotated_text.strip()
                                    # Check for potential truncation
                                    if len(citation_fragment) < 20:
                                        st.markdown("""
                                        <div class="warning-box">
                                            <strong>Warning:</strong> The citation text fragment in row {} may be truncated, which could cause verification to fail.
                                        </div>
                                        """.format(row_idx + 2), unsafe_allow_html=True)
                                    selected_citation_fragment = select_longest_segment(citation_fragment)
                                    # Recompute hash using text data
                                    recomputed_hash = generate_citation_hash(
                                        author, year, base_url, selected_citation_fragment, selected_citation_fragment,
                                        username, task_name, date, time
                                    )
                                    if recomputed_hash == scc_hash:
                                        status = "Authenticated"
                            
                            # Store result for this row
                            results.append({
                                "Username": username,
                                "Task Name": task_name,
                                "Time": time,
                                "Date": date,
                                "URL": base_url if base_url else "N/A",
                                "Author(s) Name": author if author else "N/A",
                                "Year": year if year else "N/A",
                                "Annotated Text": annotated_text,
                                "Status": status
                            })
                        
                        # Create results DataFrame
                        results_df = pd.DataFrame(results)
                        
                        # Display results
                        st.markdown("### Citation Verification Results")
                        st.markdown(results_df.to_html(classes="citations-table", index=False), unsafe_allow_html=True)
                        st.markdown(get_table_download_link(results_df, "verified_citation_data.csv"), unsafe_allow_html=True)
                        
                        # Display success message
                        if results:
                            st.markdown("""
                            <div class="success-box">
                                <strong>Citations processed successfully!</strong>
                            </div>
                            """, unsafe_allow_html=True)
                        else:
                            st.error("No valid data found in the Excel file.")
                
                except Exception as e:
                    st.error(f"Error processing Excel file: {str(e)}")
    
    st.markdown('</div>', unsafe_allow_html=True)

# Footer
st.markdown("""
<div class="footer">
    Developed by: Dr Majed Abuseif<br>
    School of Architecture and Built Environment<br>
    Deakin University<br>
    © 2025
</div>
""", unsafe_allow_html=True)