import os
import io
import streamlit as st
import docx
import docx2txt
import tempfile
import time
import re
import math
import concurrent.futures
from functools import lru_cache
from transformers import pipeline

# Set page title and hide sidebar
st.set_page_config(
    page_title="Resume-Google Job Match Analyzer",
    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)

# Pre-defined company description for Google
GOOGLE_DESCRIPTION = """Google LLC, a global leader in technology and innovation, specializes in internet services, cloud computing, artificial intelligence, and software development. As part of Alphabet Inc., Google seeks candidates with strong problem-solving skills, adaptability, and collaboration abilities. Technical roles require proficiency in programming languages such as Python, Java, C++, Go, or JavaScript, with expertise in data structures, algorithms, and system design. Additionally, skills in AI, cybersecurity, UX/UI design, and digital marketing are highly valued. Google fosters a culture of innovation, expecting candidates to demonstrate creativity, analytical thinking, and a passion for cutting-edge technology."""

#####################################
# 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 = {}
        # Use bart-base for summarization
        models['summarizer'] = pipeline(
            "summarization", 
            model="facebook/bart-base", 
            max_length=100,
            truncation=True
        )
        
        # Load model for evaluation
        models['evaluator'] = pipeline(
            "text2text-generation", 
            model="google-t5/t5-small",
            max_length=300
        )
        
        return models

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

#####################################
# Function: Extract Text from File
#####################################
@st.cache_data(show_spinner=False)
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."
    
    # Limit text size for faster processing
    return text[:15000] if text else text

#####################################
# Functions for Information Extraction
#####################################

# Cache the extraction functions to avoid reprocessing
@lru_cache(maxsize=32)
def extract_name(text_start):
    """Extract candidate name from the beginning of resume text"""
    # Only use the first 500 characters to speed up processing
    lines = text_start.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 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
    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

    return "Unknown (please extract from resume)"

def extract_age(text):
    """Extract candidate age from resume text"""
    # Simplified: just check a few common patterns
    age_patterns = [
        r'age:?\s*(\d{1,2})',
        r'(\d{1,2})\s*years\s*old',
    ]
    
    text_lower = text.lower()
    for pattern in age_patterns:
        matches = re.search(pattern, text_lower)
        if matches:
            return matches.group(1)
    
    return "Not specified"

def extract_industry(text, base_summary):
    """Extract expected job industry from resume"""
    # Simplified industry keywords focused on the most common ones
    industry_keywords = {
        "technology": ["software", "programming", "developer", "IT", "tech", "computer"],
        "finance": ["banking", "financial", "accounting", "finance", "analyst"],
        "healthcare": ["medical", "health", "hospital", "clinical", "nurse", "doctor"],
        "education": ["teaching", "teacher", "professor", "education", "university"],
        "marketing": ["marketing", "advertising", "digital marketing", "social media"],
        "engineering": ["engineer", "engineering"],
        "data science": ["data science", "machine learning", "AI", "analytics"],
        "information systems": ["information systems", "ERP", "systems management"]
    }
    
    # Count occurrences of industry keywords - using the summary to speed up
    combined_text = base_summary.lower()
    
    counts = {}
    for industry, keywords in industry_keywords.items():
        counts[industry] = sum(combined_text.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", "education", "finance", "marketing"]
    
    for degree in degrees:
        if degree in combined_text:
            return f"{degree.capitalize()}-related field"
    
    return "Not clearly specified"

def extract_skills_and_work(text):
    """Extract both skills and work experience at once to save processing time"""
    # Common skill categories - reduced keyword list for speed
    skill_categories = {
        "Programming": ["Python", "Java", "JavaScript", "HTML", "CSS", "SQL", "C++", "C#", "Go"],
        "Data Science": ["Machine Learning", "Data Analysis", "Statistics", "TensorFlow", "PyTorch", "AI", "Algorithms"],
        "Database": ["SQL", "MySQL", "MongoDB", "Database", "NoSQL", "PostgreSQL"],
        "Web Development": ["React", "Angular", "Node.js", "Frontend", "Backend", "Full-Stack"],
        "Software Development": ["Agile", "Scrum", "Git", "DevOps", "Docker", "System Design"],
        "Cloud": ["AWS", "Azure", "Google Cloud", "Cloud Computing"],
        "Security": ["Cybersecurity", "Network Security", "Encryption", "Security"],
        "Business": ["Project Management", "Business Analysis", "Leadership", "Teamwork"],
        "Design": ["UX/UI", "User Experience", "Design Thinking", "Adobe"]
    }
    
    # Work experience extraction
    work_headers = [
        "work experience", "professional experience", "employment history", 
        "work history", "experience"
    ]
    
    next_section_headers = [
        "education", "skills", "certifications", "projects", "achievements"
    ]
    
    # Process everything at once
    lines = text.split('\n')
    text_lower = text.lower()
    
    # Skills extraction
    found_skills = []
    for category, skills in skill_categories.items():
        category_skills = []
        for skill in skills:
            if skill.lower() in text_lower:
                category_skills.append(skill)
        
        if category_skills:
            found_skills.append(f"{category}: {', '.join(category_skills)}")
    
    # Work experience extraction - simplified approach
    work_section = []
    in_work_section = False
    
    for idx, line in enumerate(lines):
        line_lower = line.lower().strip()
        
        # Start of work section
        if not in_work_section:
            if any(header in line_lower for header in work_headers):
                in_work_section = True
                continue
        # End of work section
        elif in_work_section:
            if any(header in line_lower for header in next_section_headers):
                break
            
            if line.strip():
                work_section.append(line.strip())
    
    # Simplified work formatting
    if not work_section:
        work_experience = "Work experience not clearly identified"
    else:
        # Just take the first 5-7 lines of the work section as a summary
        work_lines = []
        company_count = 0
        current_company = ""
        
        for line in work_section:
            # New company entry often has a date
            if re.search(r'(19|20)\d{2}', line):
                company_count += 1
                if company_count <= 3:  # Limit to 3 most recent positions
                    current_company = line
                    work_lines.append(f"**{line}**")
                else:
                    break
            elif company_count <= 3 and len(work_lines) < 10:  # Limit total lines
                work_lines.append(line)
        
        work_experience = "\n• " + "\n• ".join(work_lines[:7]) if work_lines else "Work experience not clearly structured"
    
    skills_formatted = "\n• " + "\n• ".join(found_skills) if found_skills else "No specific technical skills clearly identified"
    
    return skills_formatted, work_experience

#####################################
# Function: Summarize Resume Text
#####################################
def summarize_resume_text(resume_text):
    """
    Generates a structured summary of the resume text
    """
    start_time = time.time()
    
    # First, generate a quick summary using pre-loaded model
    max_input_length = 1024  # Model limit
    
    # Only summarize the first portion of text for speed
    text_to_summarize = resume_text[:min(len(resume_text), max_input_length)]
    base_summary = models['summarizer'](text_to_summarize)[0]['summary_text']
    
    # Extract information in parallel where possible
    with concurrent.futures.ThreadPoolExecutor() as executor:
        # These can run in parallel
        name_future = executor.submit(extract_name, resume_text[:500])  # Only use start of text
        age_future = executor.submit(extract_age, resume_text)
        industry_future = executor.submit(extract_industry, resume_text, base_summary)
        skills_work_future = executor.submit(extract_skills_and_work, resume_text)
        
        # Get results
        name = name_future.result()
        age = age_future.result()
        industry = industry_future.result()
        skills, work_experience = skills_work_future.result()
    
    # Format the structured summary
    formatted_summary = f"Name: {name}\n"
    formatted_summary += f"Age: {age}\n"
    formatted_summary += f"Expected Job Industry: {industry}\n\n"
    formatted_summary += f"Previous Work Experience: {work_experience}\n\n"
    formatted_summary += f"Skills: {skills}"
    
    execution_time = time.time() - start_time
    
    return formatted_summary, execution_time

#####################################
# Function: Analyze Google Fit
#####################################
def analyze_google_fit(resume_summary):
    """
    Analyze how well the candidate fits Google's requirements.
    This uses the model to generate a natural language assessment with a realistic match score.
    """
    start_time = time.time()
    
    # First, calculate a realistic score based on keyword matching and balanced criteria
    google_keywords = {
        "technical_skills": ["python", "java", "c++", "javascript", "go", "sql", "algorithms", "data structures", "coding"],
        "advanced_tech": ["machine learning", "ai", "artificial intelligence", "cloud", "data science", "big data", "tensorflow", "deep learning"],
        "problem_solving": ["problem solving", "analytical", "critical thinking", "troubleshooting", "debugging", "optimization"],
        "innovation": ["innovation", "creative", "creativity", "design thinking", "research", "novel"],
        "soft_skills": ["team", "leadership", "collaboration", "communication", "agile", "project management"]
    }
    
    # Calculate realistic score with category weights
    category_weights = {
        "technical_skills": 0.35,
        "advanced_tech": 0.25,
        "problem_solving": 0.20,
        "innovation": 0.10,
        "soft_skills": 0.10
    }
    
    resume_lower = resume_summary.lower()
    category_scores = {}
    
    for category, keywords in google_keywords.items():
        # Count matches but cap at a reasonable level
        matches = sum(1 for keyword in keywords if keyword in resume_lower)
        max_matches = min(len(keywords), 5)  # Cap maximum possible matches
        
        # Calculate category score with diminishing returns
        # First few matches matter more than later ones
        if matches == 0:
            category_scores[category] = 0.0
        else:
            # Logarithmic scaling to prevent perfect scores and create more realistic distribution
            category_scores[category] = min(0.9, (math.log(matches + 1) / math.log(max_matches + 1)) * 0.9)
    
    # Calculate weighted score (max should be around 80-85% for an exceptional candidate)
    weighted_score = sum(score * category_weights[category] for category, score in category_scores.items())
    
    # Apply final curve to keep scores in a realistic range
    # Even exceptional candidates should rarely exceed 90%
    match_percentage = min(92, max(35, int(weighted_score * 100)))
    
    # Now create a focused prompt for generating the assessment
    strengths = [category.replace("_", " ") for category, score in category_scores.items() if score > 0.5]
    weaknesses = [category.replace("_", " ") for category, score in category_scores.items() if score < 0.4]
    
    # Extract key parts from resume for better context
    skills_match = re.search(r'Skills:.*?(?=\n\n|$)', resume_summary, re.DOTALL)
    skills_text = skills_match.group(0) if skills_match else ""
    
    work_match = re.search(r'Previous Work Experience:.*?(?=\n\n|$)', resume_summary, re.DOTALL)
    work_text = work_match.group(0) if work_match else ""
    
    prompt = f"""
Resume shows: {skills_text} {work_text}
Google needs: {GOOGLE_DESCRIPTION[:100]}
Analyze fit (strengths: {', '.join(strengths)}, areas for improvement: {', '.join(weaknesses)})
This candidate """
    
    try:
        # Generate the assessment
        assessment_results = models['evaluator'](
            prompt, 
            max_length=250,
            do_sample=True,
            temperature=0.4,
            num_return_sequences=2
        )
        
        # Find a good response
        assessment = None
        for result in assessment_results:
            text = result['generated_text'].strip()
            
            # Clean up obvious artifacts
            text = text.replace("This candidate This candidate", "This candidate")
            text = re.sub(r'(Resume shows:|Google needs:|Analyze fit|strengths:|areas for improvement:)', '', text)
            
            # Check if it looks valid
            if text.startswith("This candidate") and len(text) > 40:
                assessment = text
                break
        
        # If no good response was found, fall back to manual assessment
        if not assessment:
            assessment, _ = generate_manual_assessment(resume_summary, match_percentage)
            
    except Exception as e:
        # Fallback assessment with the calculated match percentage
        assessment, _ = generate_manual_assessment(resume_summary, match_percentage)
        print(f"Error in assessment generation: {e}")
    
    # Final cleanup to remove any remaining prompt artifacts
    assessment = re.sub(r'score: \d+%', '', assessment)  # Remove any existing score
    
    # Add the calculated score if not already present
    if "%" not in assessment:
        assessment += f" Overall, they have approximately a {match_percentage}% match with Google's requirements."
    
    execution_time = time.time() - start_time
    
    return assessment, match_percentage, execution_time

def generate_manual_assessment(resume_summary, match_percentage):
    """
    Generate a manual assessment based on keywords in the resume
    as a fallback when the model fails. Uses the pre-calculated match percentage.
    """
    # Define key Google skill categories
    key_skills = {
        "technical": ["python", "java", "javascript", "c++", "go", "programming", "coding", "software development"],
        "advanced_tech": ["machine learning", "ai", "artificial intelligence", "cloud", "data science", "big data"],
        "problem_solving": ["problem solving", "algorithms", "analytical", "critical thinking", "troubleshooting"],
        "innovation": ["innovation", "creative", "creativity", "design thinking"],
        "teamwork": ["team", "leadership", "collaboration", "communication", "agile"]
    }
    
    summary_lower = resume_summary.lower()
    
    # Count matches in each category
    strengths = []
    weaknesses = []
    
    for category, keywords in key_skills.items():
        matches = sum(1 for keyword in keywords if keyword in summary_lower)
        
        if matches >= 2:
            if category == "technical":
                strengths.append("strong technical skills")
            elif category == "advanced_tech":
                strengths.append("experience with advanced technologies")
            elif category == "problem_solving":
                strengths.append("problem-solving abilities")
            elif category == "innovation":
                strengths.append("innovative thinking")
            elif category == "teamwork":
                strengths.append("teamwork and collaboration skills")
        elif matches == 0:
            if category == "technical":
                weaknesses.append("technical programming skills")
            elif category == "advanced_tech":
                weaknesses.append("knowledge of advanced technologies")
            elif category == "problem_solving":
                weaknesses.append("demonstrated problem-solving capabilities")
            elif category == "innovation":
                weaknesses.append("innovation mindset")
            elif category == "teamwork":
                weaknesses.append("team collaboration experience")
    
    # Construct assessment
    assessment = f"This candidate demonstrates {', '.join(strengths[:2])} " if strengths else "This candidate "
    
    if len(strengths) > 2:
        assessment += f"as well as {strengths[2]}. "
    else:
        assessment += ". "
    
    if weaknesses:
        assessment += f"However, they could benefit from developing stronger {' and '.join(weaknesses[:2])}. "
    
    assessment += f"Based on the resume analysis, they appear to be a {match_percentage}% match for Google's requirements."
    
    return assessment, match_percentage

#####################################
# Main Streamlit Interface
#####################################
st.title("Google Resume Match Analyzer")
st.markdown(
    """
Upload your resume file in **.docx**, **.doc**, or **.txt** format to see how well you match with Google's hiring requirements. The app performs the following tasks:
1. Extracts text from your resume.
2. Uses AI to generate a structured candidate summary.
3. Analyzes how well your profile fits Google's requirements.
"""
)

# Display Google's requirements
with st.expander("Google's Requirements", expanded=False):
    st.write(GOOGLE_DESCRIPTION)

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

# Process button with optimized flow
if uploaded_file is not None and st.button("Analyze My Google Fit"):
    # Create a placeholder for the progress bar
    progress_bar = st.progress(0)
    status_text = st.empty()
    
    # Step 1: Extract text
    status_text.text("Step 1/3: Extracting text from resume...")
    resume_text = extract_text_from_file(uploaded_file)
    progress_bar.progress(25)
    
    if resume_text.startswith("Error") or resume_text == "Unsupported file type. Please upload a .docx, .doc, or .txt file.":
        st.error(resume_text)
    else:
        # Step 2: Generate summary
        status_text.text("Step 2/3: Analyzing resume and generating summary...")
        summary, summarization_time = summarize_resume_text(resume_text)
        progress_bar.progress(50)
        
        # Display summary
        st.subheader("Your Resume Summary")
        st.markdown(summary)
        st.info(f"Summary generated in {summarization_time:.2f} seconds")
        
        # Step 3: Generate Google fit assessment
        status_text.text("Step 3/3: Evaluating Google fit...")
        assessment, match_percentage, assessment_time = analyze_google_fit(summary)
        progress_bar.progress(100)
        
        # Clear status messages
        status_text.empty()
        
        # Display Google fit results
        st.subheader("Google Fit Assessment")

        # Display match percentage with appropriate color and emoji - with more realistic thresholds
        if match_percentage >= 85:
            st.success(f"**Overall Google Match Score:** {match_percentage}% 🌟")
        elif match_percentage >= 70:
            st.success(f"**Overall Google Match Score:** {match_percentage}% ✅")
        elif match_percentage >= 50:
            st.warning(f"**Overall Google Match Score:** {match_percentage}% ⚠️")
        else:
            st.error(f"**Overall Google Match Score:** {match_percentage}% 🔍")

        # Display assessment
        st.markdown("### Expert Assessment")
        st.markdown(assessment)
        
        st.info(f"Assessment completed in {assessment_time:.2f} seconds")
        
        # Add potential next steps based on the match percentage
        st.subheader("Recommended Next Steps")
        
        if match_percentage >= 80:
            st.markdown("""
            - Consider applying for positions at Google that match your experience
            - Prepare for technical interviews by practicing algorithms and system design
            - Review Google's interview process and STAR method for behavioral questions
            """)
        elif match_percentage >= 60:
            st.markdown("""
            - Focus on strengthening your technical skills and advanced technology knowledge
            - Work on projects that demonstrate your skills in Google's key technology areas
            - Consider taking additional courses in algorithms, system design, or other Google focus areas
            """)
        else:
            st.markdown("""
            - Build more relevant experience in software development or technical areas
            - Develop projects showcasing problem-solving abilities and technical skills
            - Consider gaining more experience before applying, or target specific Google roles that better match your profile
            """)