import os, io, re, time, tempfile
import streamlit as st
import docx, docx2txt
import pandas as pd
from functools import lru_cache

# Handle imports
try:
    from transformers import pipeline
    has_pipeline = True
except ImportError:
    from transformers import AutoModelForSequenceClassification, AutoTokenizer, AutoModelForSeq2SeqLM
    import torch
    has_pipeline = False

# Setup page
st.set_page_config(page_title="Resume-Job Fit Analyzer", initial_sidebar_state="collapsed")
st.markdown("""<style>[data-testid="collapsedControl"],[data-testid="stSidebar"] {display: none;}</style>""", unsafe_allow_html=True)

#####################################
# Model Loading & Text Processing
#####################################
@st.cache_resource
def load_models():
    with st.spinner("Loading AI models..."):
        models = {}
        # Load summarization model
        if has_pipeline:
            models['summarizer'] = pipeline("summarization", model="Falconsai/text_summarization", max_length=100)
        else:
            try:
                models['summarizer_model'] = AutoModelForSeq2SeqLM.from_pretrained("Falconsai/text_summarization")
                models['summarizer_tokenizer'] = AutoTokenizer.from_pretrained("Falconsai/text_summarization")
            except Exception as e:
                st.error(f"Error loading summarization model: {e}")
                models['summarizer_model'] = models['summarizer_tokenizer'] = None
        
        # Load evaluation model
        if has_pipeline:
            models['evaluator'] = pipeline("sentiment-analysis", model="CR7CAD/RobertaFinetuned")
        else:
            try:
                models['evaluator_model'] = AutoModelForSequenceClassification.from_pretrained("CR7CAD/RobertaFinetuned")
                models['evaluator_tokenizer'] = AutoTokenizer.from_pretrained("CR7CAD/RobertaFinetuned")
            except Exception as e:
                st.error(f"Error loading sentiment model: {e}")
                models['evaluator_model'] = models['evaluator_tokenizer'] = None
        return models

def summarize_text(text, models, max_length=100):
    """Summarize text with fallbacks"""
    input_text = text[:1024]
    
    # Try pipeline
    if has_pipeline and 'summarizer' in models:
        try:
            return models['summarizer'](input_text)[0]['summary_text']
        except: pass
    
    # Try manual model
    if 'summarizer_model' in models and models['summarizer_model']:
        try:
            tokenizer = models['summarizer_tokenizer']
            model = models['summarizer_model']
            inputs = tokenizer(input_text, return_tensors="pt", truncation=True, max_length=1024)
            summary_ids = model.generate(inputs.input_ids, max_length=max_length, min_length=30, num_beams=4)
            return tokenizer.decode(summary_ids[0], skip_special_tokens=True)
        except: pass
    
    # Fallback - extract sentences
    sentences = re.split(r'(?<!\w\.\w.)(?<![A-Z][a-z]\.)(?<=\.|\?)\s', text)
    scored = [(1.0/(i+1), s) for i, s in enumerate(sentences) if len(s.split()) >= 4]
    scored.sort(reverse=True)
    
    result, length = [], 0
    for _, sentence in scored:
        if length + len(sentence.split()) <= max_length:
            result.append(sentence)
            length += len(sentence.split())
    
    if result:
        ordered = sorted([(sentences.index(s), s) for s in result])
        return " ".join(s for _, s in ordered)
    return ""

#####################################
# File Processing & Information Extraction
#####################################
@st.cache_data
def extract_text_from_file(file_obj):
    ext = os.path.splitext(file_obj.name)[1].lower()
    
    if ext == ".docx":
        try:
            document = docx.Document(file_obj)
            return "\n".join(para.text for para in document.paragraphs if para.text.strip())[:15000]
        except Exception as e:
            return f"Error processing DOCX file: {e}"
    elif ext == ".doc":
        try:
            with tempfile.NamedTemporaryFile(delete=False, suffix='.doc') as temp_file:
                temp_file.write(file_obj.getvalue())
                text = docx2txt.process(temp_file.name)
                os.unlink(temp_file.name)
                return text[:15000]
        except Exception as e:
            return f"Error processing DOC file: {e}"
    elif ext == ".txt":
        try:
            return file_obj.getvalue().decode("utf-8")[:15000]
        except Exception as e:
            return f"Error processing TXT file: {e}"
    else:
        return "Unsupported file type. Please upload a .docx, .doc, or .txt file."

# Information extraction functions
def extract_skills(text):
    """Extract skills from text - expanded for better matching"""
    # Expanded skill keywords dictionary
    skill_keywords = {
        "Programming": ["Python", "Java", "JavaScript", "HTML", "CSS", "SQL", "C++", "C#", "React", "Angular", "Vue", 
                      "PHP", "Ruby", "Swift", "Kotlin", "Go", "TypeScript", "Node.js", "jQuery", "Bootstrap"],
        "Data Science": ["Machine Learning", "Data Analysis", "Statistics", "TensorFlow", "PyTorch", "AI", "NLP",
                        "Data Mining", "Big Data", "Data Visualization", "Statistical Analysis", "R", "SPSS", "SAS",
                        "Regression", "Classification", "Clustering", "Neural Networks", "Deep Learning"],
        "Database": ["SQL", "MySQL", "MongoDB", "PostgreSQL", "Oracle", "Redis", "DynamoDB", "SQLite", "NoSQL", 
                    "Database Design", "SQL Server", "Database Administration", "ETL", "Data Warehousing"],
        "Web Dev": ["React", "Angular", "Node.js", "Frontend", "Backend", "Full-Stack", "REST API", "GraphQL",
                  "Web Development", "WordPress", "Drupal", "CMS", "SEO", "UI/UX", "Responsive Design", "AJAX"],
        "Software Dev": ["Agile", "Scrum", "Git", "DevOps", "Docker", "CI/CD", "Jenkins", "Software Development",
                       "Object-Oriented Programming", "Design Patterns", "Testing", "QA", "Software Architecture",
                       "Version Control", "JIRA", "Microservices", "Code Review", "Debugging"],
        "Cloud": ["AWS", "Azure", "Google Cloud", "Lambda", "S3", "EC2", "Cloud Computing", "Serverless", 
                "Infrastructure as Code", "Cloud Architecture", "Cloud Security", "Kubernetes", "Load Balancing"],
        "Business": ["Project Management", "Leadership", "Teamwork", "Agile", "Scrum", "Business Analysis",
                    "Requirements Gathering", "Client Relations", "Communication", "Presentation", "Meeting Facilitation",
                    "Strategic Planning", "Process Improvement", "Problem Solving", "Decision Making", "Stakeholder Management"]
    }
    
    text_lower = text.lower()
    
    # Method 1: Look for exact matches
    exact_skills = [skill for _, skills in skill_keywords.items() for skill in skills if skill.lower() in text_lower]
    
    # Method 2: Use regex for more flexible matching (accounts for variations)
    more_skills = []
    for category, skills in skill_keywords.items():
        for skill in skills:
            # This handles cases like "Python developer" or "experienced in Python"
            if re.search(r'\b' + re.escape(skill.lower()) + r'(?:\s|\b|ing|er|ed)', text_lower):
                more_skills.append(skill)
    
    # Combine both methods and remove duplicates
    all_skills = list(set(exact_skills + more_skills))
    
    # Add soft skill detection
    soft_skills = ["Communication", "Teamwork", "Problem Solving", "Critical Thinking", 
                  "Leadership", "Organization", "Time Management", "Flexibility", "Adaptability"]
    
    for skill in soft_skills:
        if skill.lower() in text_lower or re.search(r'\b' + re.escape(skill.lower()) + r'(?:\s|$)', text_lower):
            all_skills.append(skill)
    
    return all_skills

@lru_cache(maxsize=32)
def extract_name(text_start):
    lines = [line.strip() for line in text_start.split('\n')[:5] if line.strip()]
    
    if lines:
        first_line = lines[0]
        if 5 <= len(first_line) <= 40 and not any(x in first_line.lower() for x in ["resume", "cv", "curriculum", "vitae"]):
            return first_line
    
    for line in 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"

def extract_age(text):
    for pattern in [r'age:?\s*(\d{1,2})', r'(\d{1,2})\s*years\s*old', r'dob:.*(\d{4})', r'date of birth:.*(\d{4})']:
        match = re.search(pattern, text.lower())
        if match:
            if len(match.group(1)) == 4:  # Birth year
                try: return str(2025 - int(match.group(1)))
                except: pass
            return match.group(1)
    return "Not specified"

def extract_industry(text):
    industries = {
        "Technology": ["software", "programming", "developer", "IT", "tech", "computer", "digital"],
        "Finance": ["banking", "financial", "accounting", "finance", "analyst"],
        "Healthcare": ["medical", "health", "hospital", "clinical", "nurse", "doctor"],
        "Education": ["teaching", "teacher", "professor", "education", "university", "school"],
        "Marketing": ["marketing", "advertising", "digital marketing", "social media", "brand"],
        "Engineering": ["engineer", "engineering", "mechanical", "civil", "electrical"],
        "Data Science": ["data science", "machine learning", "AI", "analytics", "big data"],
        "Management": ["manager", "management", "leadership", "executive", "director"]
    }
    
    text_lower = text.lower()
    counts = {ind: sum(text_lower.count(kw) for kw in kws) for ind, kws in industries.items()}
    return max(counts.items(), key=lambda x: x[1])[0] if any(counts.values()) else "Not specified"

def extract_job_position(text):
    text_lower = text.lower()
    for pattern in [r'objective:?\s*(.*?)(?=\n\n|\n\w+:|\Z)', r'career\s*objective:?\s*(.*?)(?=\n\n|\n\w+:|\Z)', 
                   r'summary:?\s*(.*?)(?=\n\n|\n\w+:|\Z)', r'seeking.*position.*as\s*([^.]*)']:
        match = re.search(pattern, text_lower, re.IGNORECASE | re.DOTALL)
        if match:
            text = match.group(1).strip()
            for title in ["developer", "engineer", "analyst", "manager", "specialist", "designer"]:
                if title in text:
                    return next((m.group(1).strip().title() for m in 
                               [re.search(r'(\w+\s+' + title + r')', text)] if m), title.title())
            return " ".join(text.split()[:10]).title() + "..." if len(text.split()) > 10 else text.title()
    
    # Check for job title near experience
    for pattern in [r'experience:.*?(\w+\s+\w+(?:\s+\w+)?)(?=\s*at|\s*\()', r'(\w+\s+\w+(?:\s+\w+)?)\s*\(\s*(?:current|present)']:
        match = re.search(pattern, text_lower, re.IGNORECASE)
        if match: return match.group(1).strip().title()
    
    return "Not specified"

#####################################
# Core Analysis Functions
#####################################
def summarize_resume_text(resume_text, models):
    start = time.time()
    
    # Basic info extraction
    name = extract_name(resume_text[:500])
    age = extract_age(resume_text)
    industry = extract_industry(resume_text)
    job_position = extract_job_position(resume_text)
    skills = extract_skills(resume_text)
    
    # Generate summary
    try:
        if has_pipeline and 'summarizer' in models:
            model_summary = models['summarizer'](resume_text[:2000], max_length=100, min_length=30)[0]['summary_text']
        else:
            model_summary = summarize_text(resume_text, models, max_length=100)
    except:
        model_summary = "Error generating summary."
    
    # Format result
    summary = f"Name: {name}\n\nAge: {age}\n\nExpected Industry: {industry}\n\n"
    summary += f"Expected Job Position: {job_position}\n\nSkills: {', '.join(skills)}\n\nSummary: {model_summary}"
    
    return summary, time.time() - start

def extract_job_requirements(job_description, models):
    # Expanded technical skills list for better matching
    tech_skills = [
        "Python", "Java", "JavaScript", "SQL", "HTML", "CSS", "React", "Angular", "Vue", "Node.js",
        "Machine Learning", "Data Science", "AI", "Deep Learning", "NLP", "Statistics", "TensorFlow", 
        "AWS", "Azure", "Google Cloud", "Docker", "Kubernetes", "CI/CD", "DevOps",
        "MySQL", "MongoDB", "PostgreSQL", "Oracle", "NoSQL", "Database", "Data Analysis",
        "Project Management", "Agile", "Scrum", "Leadership", "Communication", "Teamwork",
        "Git", "Software Development", "Full Stack", "Frontend", "Backend", "RESTful API",
        "Mobile Development", "Android", "iOS", "Swift", "Kotlin", "React Native", "Flutter",
        "Business Analysis", "Requirements", "UX/UI", "Design", "Product Management",
        "Testing", "QA", "Security", "Cloud Computing", "Networking", "System Administration",
        "Linux", "Windows", "Excel", "PowerPoint", "Word", "Microsoft Office",
        "Problem Solving", "Critical Thinking", "Analytical Skills"
    ]
    
    clean_text = job_description.lower()
    
    # Extract job title
    job_title = "Not specified"
    for pattern in [r'^([^:.\n]+?)(position|role|job)', r'^([^:.\n]+?)\n', r'hiring.*? ([^:.\n]+?)(:-|[.:]|\n|$)']:
        match = re.search(pattern, clean_text, re.IGNORECASE)
        if match:
            title = match.group(1).strip() if len(match.groups()) >= 1 else match.group(2).strip()
            if 3 <= len(title) <= 50:
                job_title = title.capitalize()
                break
    
    # Extract years required
    years_required = 0
    for pattern in [r'(\d+)(?:\+)?\s*(?:years|yrs).*?experience', r'experience.*?(\d+)(?:\+)?\s*(?:years|yrs)']:
        match = re.search(pattern, clean_text, re.IGNORECASE)
        if match:
            try:
                years_required = int(match.group(1))
                break
            except: pass
    
    # Extract skills
    required_skills = [skill for skill in tech_skills if re.search(r'\b' + re.escape(skill.lower()) + r'\b', clean_text)]
    
    # Fallback if no skills found
    if not required_skills:
        words = [w for w in re.findall(r'\b\w{4,}\b', clean_text) 
                if w not in ["with", "that", "this", "have", "from", "they", "will", "what", "your"]]
        word_counts = {}
        for w in words: word_counts[w] = word_counts.get(w, 0) + 1
        required_skills = [w.capitalize() for w, _ in sorted(word_counts.items(), key=lambda x: x[1], reverse=True)[:5]]
    
    return {
        "title": job_title,
        "years_experience": years_required,
        "required_skills": required_skills,
        "summary": summarize_text(job_description, models, max_length=100)
    }

def evaluate_job_fit(resume_summary, job_requirements, models):
    start = time.time()
    
    # Basic extraction
    required_skills = job_requirements["required_skills"]
    years_required = job_requirements["years_experience"]
    job_title = job_requirements["title"]
    skills_mentioned = extract_skills(resume_summary)
    
    # Calculate matches - IMPROVED MATCHING ALGORITHM
    matching_skills = [skill for skill in required_skills if skill in skills_mentioned]
    
    # More balanced skill match calculation:
    # - If no required skills, default to 0.5 (neutral)
    # - Otherwise calculate percentage but with diminishing returns
    if not required_skills:
        skill_match = 0.5
    else:
        raw_match = len(matching_skills) / len(required_skills)
        # Apply a more gradual scaling to avoid big jumps
        skill_match = raw_match ** 0.7  # Using power < 1 gives more weight to partial matches
    
    # Extract experience
    years_experience = 0
    exp_match = re.search(r'(\d+)\+?\s*years?\s*(?:of)?\s*experience', resume_summary, re.IGNORECASE)
    if exp_match:
        try: years_experience = int(exp_match.group(1))
        except: pass
    
    # Calculate scores with smoother transitions
    # Experience matching: more balanced, handles the case where job requires no experience
    if years_required == 0:
        # If no experience required, having 1+ years is good, 0 is neutral
        exp_match_ratio = min(1.0, years_experience / 2 + 0.5)
    else:
        # For jobs requiring experience, use a more gradual scale
        exp_match_ratio = min(1.0, (years_experience / max(1, years_required)) ** 0.8)
    
    # Title matching - improved to find partial matches
    title_words = [w for w in job_title.lower().split() if len(w) > 3]
    if not title_words:
        title_match = 0.5  # Neutral if no meaningful title words
    else:
        matches = 0
        for word in title_words:
            if word in resume_summary.lower():
                matches += 1
            # Look for similar words (prefixes) for partial matching
            elif any(w.startswith(word[:4]) for w in resume_summary.lower().split() if len(w) > 3):
                matches += 0.5
        title_match = matches / len(title_words)
    
    # Calculate final scores with more reasonable ranges
    skill_score = skill_match * 2.0  # 0-2 scale
    exp_score = exp_match_ratio * 2.0  # 0-2 scale
    title_score = title_match * 2.0  # 0-2 scale
    
    # Extract candidate info
    name = re.search(r'Name:\s*(.*?)(?=\n|\Z)', resume_summary)
    name = name.group(1).strip() if name else "The candidate"
    
    industry = re.search(r'Expected Industry:\s*(.*?)(?=\n|\Z)', resume_summary)
    industry = industry.group(1).strip() if industry else "unspecified industry"
    
    # Calculate weighted score - ADJUSTED WEIGHTS
    weighted_score = (skill_score * 0.45) + (exp_score * 0.35) + (title_score * 0.20)
    
    # IMPROVED THRESHOLDS to get more "Potential Fit" results
    # Good Fit: 1.25+ (was 1.5)
    # Potential Fit: 0.6-1.25 (was 0.8-1.5)
    # No Fit: <0.6 (was <0.8)
    if weighted_score >= 1.25:
        fit_score = 2  # Good fit
    elif weighted_score >= 0.6:
        fit_score = 1  # Potential fit - wider range
    else:
        fit_score = 0  # Not a fit
    
    # Add logging to help debug the scoring
    st.session_state['debug_scores'] = {
        'skill_match': skill_match,
        'skill_score': skill_score,
        'exp_match_ratio': exp_match_ratio,
        'exp_score': exp_score,
        'title_match': title_match,
        'title_score': title_score,
        'weighted_score': weighted_score,
        'fit_score': fit_score,
        'matching_skills': matching_skills,
        'required_skills': required_skills
    }
    
    # Generate assessment
    missing = [skill for skill in required_skills if skill not in skills_mentioned]
    
    if fit_score == 2:
        assessment = f"{fit_score}: GOOD FIT - {name} demonstrates strong alignment with the {job_title} position. Their background in {industry} appears well-suited for this role's requirements."
    elif fit_score == 1:
        assessment = f"{fit_score}: POTENTIAL FIT - {name} shows potential for the {job_title} role but has gaps in certain areas. Additional training might be needed in {', '.join(missing[:2])}."
    else:
        assessment = f"{fit_score}: NO FIT - {name}'s background shows limited alignment with this {job_title} position. Their experience and skills differ significantly from the requirements."
    
    return assessment, fit_score, time.time() - start

def analyze_job_fit(resume_summary, job_description, models):
    start = time.time()
    job_requirements = extract_job_requirements(job_description, models)
    assessment, fit_score, _ = evaluate_job_fit(resume_summary, job_requirements, models)
    return assessment, fit_score, time.time() - start

#####################################
# Main Function
#####################################
def main():
    # Initialize session state for debug info
    if 'debug_scores' not in st.session_state:
        st.session_state['debug_scores'] = {}
        
    st.title("Resume-Job Fit Analyzer")
    st.markdown("Upload your resume file in **.docx**, **.doc**, or **.txt** format and enter a job description to see how well you match.")

    # Load models and get inputs
    models = load_models()
    uploaded_file = st.file_uploader("Upload your resume", type=["docx", "doc", "txt"])
    job_description = st.text_area("Enter Job Description", height=200, placeholder="Paste the job description here...")

    # Process when button clicked
    if uploaded_file and job_description and st.button("Analyze Job Fit"):
        progress = st.progress(0)
        status = st.empty()
        
        # Step 1: Extract text
        status.text("Step 1/3: Extracting text from resume...")
        resume_text = extract_text_from_file(uploaded_file)
        progress.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("Step 2/3: Analyzing resume...")
            summary, summary_time = summarize_resume_text(resume_text, models)
            progress.progress(50)
            st.subheader("Your Resume Summary")
            st.markdown(summary)
            
            # Step 3: Evaluate fit
            status.text("Step 3/3: Evaluating job fit...")
            assessment, fit_score, eval_time = analyze_job_fit(summary, job_description, models)
            progress.progress(100)
            status.empty()

            # Display results
            st.subheader("Job Fit Assessment")
            fit_labels = {0: "NOT FIT", 1: "POTENTIAL FIT", 2: "GOOD FIT"}
            colors = {0: "red", 1: "orange", 2: "green"}
            st.markdown(f"<h2 style='color: {colors[fit_score]};'>{fit_labels[fit_score]}</h2>", unsafe_allow_html=True)
            st.markdown(assessment)
            st.info(f"Analysis completed in {(summary_time + eval_time):.2f} seconds")
            
            # Recommendations
            st.subheader("Recommended Next Steps")
            if fit_score == 2:
                st.markdown("""
                - Apply for this position as you appear to be a good match
                - Prepare for interviews by focusing on your relevant experience
                - Highlight your matching skills in your cover letter
                """)
            elif fit_score == 1:
                st.markdown("""
                - Consider applying but address skill gaps in your cover letter
                - Emphasize transferable skills and relevant experience
                - Prepare to discuss how you can quickly develop missing skills
                """)
            else:
                st.markdown("""
                - Look for positions better aligned with your current skills
                - If interested in this field, focus on developing the required skills
                - Consider similar roles with fewer experience requirements
                """)
            
            # Show debug scores if needed (uncomment this to debug scoring)
            # st.subheader("Debug Information")
            # st.json(st.session_state['debug_scores'])

if __name__ == "__main__":
    main()