import os
import io
import streamlit as st
import docx
import docx2txt
import tempfile
from transformers import pipeline
import numpy as np
from scipy.spatial.distance import cosine
import time
import re

# Set page title and hide sidebar
st.set_page_config(
    page_title="Resume Analyzer and Company Suitability Checker",
    initial_sidebar_state="collapsed"
)

# Hide sidebar completely with custom CSS
st.markdown("""
<style>
    [data-testid="collapsedControl"] {display: none;}
    section[data-testid="stSidebar"] {display: none;}
</style>
""", unsafe_allow_html=True)

#####################################
# Preload Models
#####################################
@st.cache_resource(show_spinner=True)
def load_models():
    """Load models at startup"""
    with st.spinner("Loading AI models... This may take a minute on first run."):
        models = {}
        # Load summarization model
        models['summarizer'] = pipeline("summarization", model="t5-base")
        
        # Load feature extraction model for similarity
        models['feature_extractor'] = pipeline("feature-extraction", model="bert-base-uncased")
        
        return models

# Preload models immediately when app starts
models = load_models()

#####################################
# Function: Extract Text from File
#####################################
def extract_text_from_file(file_obj):
    """
    Extract text from .docx and .doc files.
    Returns the extracted text or an error message if extraction fails.
    """
    filename = file_obj.name
    ext = os.path.splitext(filename)[1].lower()
    text = ""

    if ext == ".docx":
        try:
            document = docx.Document(file_obj)
            text = "\n".join(para.text for para in document.paragraphs if para.text.strip())
        except Exception as e:
            text = f"Error processing DOCX file: {e}"
    elif ext == ".doc":
        try:
            # For .doc files, we need to save to a temp file
            with tempfile.NamedTemporaryFile(delete=False, suffix='.doc') as temp_file:
                temp_file.write(file_obj.getvalue())
                temp_path = temp_file.name
        
            # Use docx2txt which is generally faster
            try:
                text = docx2txt.process(temp_path)
            except Exception:
                text = "Could not process .doc file. Please convert to .docx format."
        
            # Clean up temp file
            os.unlink(temp_path)
        except Exception as e:
            text = f"Error processing DOC file: {e}"
    elif ext == ".txt":
        try:
            text = file_obj.getvalue().decode("utf-8")
        except Exception as e:
            text = f"Error processing TXT file: {e}"
    else:
        text = "Unsupported file type. Please upload a .docx, .doc, or .txt file."
    return text

#####################################
# Functions for Information Extraction
#####################################
def extract_name(text):
    """Extract candidate name from resume text"""
    # Look for common name patterns at the beginning of resumes
    lines = text.split('\n')
    
    # Check first few non-empty lines for potential names
    potential_name_lines = [line.strip() for line in lines[:5] if line.strip()]
    
    if potential_name_lines:
        # First line is often the name if it's short and doesn't contain common resume headers
        first_line = potential_name_lines[0]
        if 5 <= len(first_line) <= 40 and not any(x in first_line.lower() for x in ["resume", "cv", "curriculum", "vitae", "profile"]):
            return first_line
    
    # Look for lines that might contain a name (not containing common keywords)
    for line in potential_name_lines[:3]:
        if len(line.split()) <= 4 and not any(x in line.lower() for x in ["address", "phone", "email", "resume", "cv"]):
            return line

    # If we couldn't find a clear name
    return "Unknown (please extract from resume)"

def extract_age(text):
    """Extract candidate age from resume text"""
    # Look for common age patterns
    
    # Look for patterns like "Age: XX" or "XX years old"
    age_patterns = [
        r'age:?\s*(\d{1,2})',
        r'(\d{1,2})\s*years\s*old',
        r'DOB:?\s*(\d{1,2})[/-](\d{1,2})[/-](\d{2,4})'
    ]
    
    for pattern in age_patterns:
        matches = re.search(pattern, text.lower())
        if matches:
            if pattern == age_patterns[2]:  # DOB pattern
                # Calculate age from DOB - simplified
                return "Mentioned in DOB format"
            else:
                return matches.group(1)
    
    return "Not specified"

def extract_industry(text, summary):
    """Extract expected job industry from resume"""
    # Look for industry-related keywords
    industry_keywords = {
        "technology": ["software", "programming", "developer", "IT", "tech", "computer", "web", "data science"],
        "finance": ["banking", "investment", "financial", "accounting", "finance", "analyst"],
        "healthcare": ["medical", "health", "hospital", "clinical", "nurse", "doctor", "patient"],
        "education": ["teaching", "teacher", "professor", "academic", "education", "school", "university"],
        "marketing": ["marketing", "advertising", "brand", "digital marketing", "SEO", "social media"],
        "engineering": ["mechanical", "civil", "electrical", "engineer", "engineering"],
        "consulting": ["consultant", "consulting", "advisory"],
        "data science": ["data science", "machine learning", "AI", "analytics", "big data"],
        "information systems": ["information systems", "ERP", "CRM", "database", "systems management"]
    }
    
    # Count occurrences of industry keywords
    counts = {}
    text_lower = text.lower()
    
    for industry, keywords in industry_keywords.items():
        counts[industry] = sum(text_lower.count(keyword.lower()) for keyword in keywords)
    
    # Get the industry with the highest count
    if counts:
        likely_industry = max(counts.items(), key=lambda x: x[1])
        if likely_industry[1] > 0:
            return likely_industry[0].capitalize()
    
    # Check for educational background that might indicate industry
    degrees = ["computer science", "business", "engineering", "medicine", "law", "education", 
              "finance", "marketing", "information systems"]
    
    for degree in degrees:
        if degree in text_lower:
            return f"{degree.capitalize()}-related field"
    
    return "Not clearly specified (review resume for details)"

def extract_skills(text, summary):
    """Extract key skills from resume"""
    # Common skill categories and associated keywords
    skill_categories = {
        "Programming": ["Python", "Java", "C++", "JavaScript", "HTML", "CSS", "SQL", "R", "C#", "PHP", 
                       "Ruby", "Swift", "TypeScript", "Go", "Scala", "Kotlin", "Rust"],
        "Data Science": ["Machine Learning", "Deep Learning", "NLP", "Data Analysis", "Statistics", 
                         "Big Data", "Data Visualization", "TensorFlow", "PyTorch", "Neural Networks", 
                         "Regression", "Classification", "Clustering"],
        "Database": ["SQL", "MySQL", "PostgreSQL", "MongoDB", "Oracle", "SQLite", "NoSQL", "Database Design", 
                    "Data Modeling", "ETL", "Data Warehousing"],
        "Web Development": ["React", "Angular", "Vue.js", "Node.js", "Django", "Flask", "Express", "RESTful API", 
                           "Frontend", "Backend", "Full-Stack", "Responsive Design"],
        "Software Development": ["Agile", "Scrum", "Kanban", "Git", "CI/CD", "TDD", "OOP", "Design Patterns", 
                                "Microservices", "DevOps", "Docker", "Kubernetes"],
        "Cloud": ["AWS", "Azure", "Google Cloud", "Cloud Computing", "S3", "EC2", "Lambda", "Serverless", 
                 "Cloud Architecture", "IaaS", "PaaS", "SaaS"],
        "Business": ["Project Management", "Business Analysis", "Communication", "Teamwork", "Leadership", 
                    "Strategy", "Negotiation", "Presentation", "Time Management"],
        "Tools": ["Excel", "PowerPoint", "Tableau", "Power BI", "JIRA", "Confluence", "Slack", "Microsoft Office", 
                 "Adobe", "Photoshop", "Salesforce"]
    }
    
    # Find skills mentioned in the resume
    found_skills = []
    text_lower = text.lower()
    
    for category, skills in skill_categories.items():
        category_skills = []
        for skill in skills:
            # Check for case-insensitive match but preserve original case in output
            if skill.lower() in text_lower:
                category_skills.append(skill)
        
        if category_skills:
            found_skills.append(f"{category}: {', '.join(category_skills)}")
    
    if found_skills:
        return "\n• " + "\n• ".join(found_skills)
    else:
        return "No specific technical skills clearly identified (review resume for details)"

#####################################
# Function: Summarize Resume Text
#####################################
def summarize_resume_text(resume_text, models):
    """
    Generates a structured summary of the resume text including name, age, 
    expected job industry, and skills of the candidate.
    """
    start_time = time.time()
    
    summarizer = models['summarizer']
    
    # First, generate a general summary
    max_input_length = 1024  # Model limit
    
    if len(resume_text) > max_input_length:
        chunks = [resume_text[i:i+max_input_length] for i in range(0, min(len(resume_text), 3*max_input_length), max_input_length)]
        summaries = []
        
        for chunk in chunks:
            chunk_summary = summarizer(chunk, max_length=150, min_length=30, do_sample=False)[0]['summary_text']
            summaries.append(chunk_summary)
        
        base_summary = " ".join(summaries)
    else:
        base_summary = summarizer(resume_text, max_length=150, min_length=30, do_sample=False)[0]['summary_text']
    
    # Extract specific information using custom extraction logic
    name = extract_name(resume_text)
    age = extract_age(resume_text)
    industry = extract_industry(resume_text, base_summary)
    skills = extract_skills(resume_text, base_summary)
    
    # Format the structured summary
    formatted_summary = f"Name: {name}\n"
    formatted_summary += f"Age: {age}\n"
    formatted_summary += f"Expected Job Industry: {industry}\n"
    formatted_summary += f"Skills: {skills}"
    
    execution_time = time.time() - start_time
    
    return formatted_summary, execution_time

#####################################
# Function: Compare Candidate Summary to Company Prompt
#####################################
def compute_suitability(candidate_summary, company_prompt, models):
    """
    Compute the similarity between candidate summary and company prompt.
    Returns a score in the range [0, 1] and execution time.
    """
    start_time = time.time()
    
    feature_extractor = models['feature_extractor']
    
    # Extract features (embeddings)
    candidate_features = feature_extractor(candidate_summary)
    company_features = feature_extractor(company_prompt)
    
    # Convert to numpy arrays and flatten if needed
    candidate_vec = np.mean(np.array(candidate_features[0]), axis=0)
    company_vec = np.mean(np.array(company_features[0]), axis=0)
    
    # Compute cosine similarity (1 - cosine distance)
    similarity = 1 - cosine(candidate_vec, company_vec)
    
    execution_time = time.time() - start_time
    
    return similarity, execution_time

#####################################
# Main Streamlit Interface
#####################################
st.title("Resume Analyzer and Company Suitability Checker")
st.markdown(
    """
Upload your resume file in **.docx**, **.doc**, or **.txt** format. The app performs the following tasks:
1. Extracts text from the resume.
2. Uses AI to generate a structured candidate summary with name, age, expected job industry, and skills.
3. Compares the candidate summary with a company profile to produce a suitability score.
"""
)

# File uploader
uploaded_file = st.file_uploader("Upload your resume (.docx, .doc, or .txt)", type=["docx", "doc", "txt"])

# Company description text area
company_prompt = st.text_area(
    "Enter the company description or job requirements:",
    height=150,
    help="Enter a detailed description of the company culture, role requirements, and desired skills.",
)

# Process button
if uploaded_file is not None and company_prompt and st.button("Analyze Resume"):
    with st.spinner("Processing..."):
        # Extract text from resume
        resume_text = extract_text_from_file(uploaded_file)
        
        if resume_text.startswith("Error") or resume_text == "Unsupported file type. Please upload a .docx, .doc, or .txt file.":
            st.error(resume_text)
        else:
            # Generate summary
            summary, summarization_time = summarize_resume_text(resume_text, models)
            
            # Display summary
            st.subheader("Candidate Summary")
            st.markdown(summary)
            st.info(f"Summarization completed in {summarization_time:.2f} seconds")
            
            # Only compute similarity if company description is provided
            if company_prompt:
                similarity_score, similarity_time = compute_suitability(summary, company_prompt, models)
                
                # Display similarity score
                st.subheader("Suitability Assessment")
                st.markdown(f"**Matching Score:** {similarity_score:.2%}")
                st.info(f"Similarity computation completed in {similarity_time:.2f} seconds")
                
                # Provide interpretation
                if similarity_score >= 0.85:
                    st.success("Excellent match! This candidate's profile is strongly aligned with the company requirements.")
                elif similarity_score >= 0.70:
                    st.success("Good match! This candidate shows strong potential for the position.")
                elif similarity_score >= 0.50:
                    st.warning("Moderate match. The candidate meets some requirements but there may be gaps.")
                else:
                    st.error("Low match. The candidate's profile may not align well with the requirements.")