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"""
    skill_keywords = {
        "Programming": ["Python", "Java", "JavaScript", "HTML", "CSS", "SQL", "C++", "C#", "React", "Angular"],
        "Data Science": ["Machine Learning", "Data Analysis", "Statistics", "TensorFlow", "PyTorch", "AI", "NLP"],
        "Database": ["SQL", "MySQL", "MongoDB", "PostgreSQL", "Oracle", "Redis"],
        "Web Dev": ["React", "Angular", "Node.js", "Frontend", "Backend", "Full-Stack", "REST API"],
        "Software Dev": ["Agile", "Scrum", "Git", "DevOps", "Docker", "CI/CD", "Jenkins"],
        "Cloud": ["AWS", "Azure", "Google Cloud", "Lambda", "S3", "EC2"],
        "Business": ["Project Management", "Leadership", "Teamwork", "Agile", "Scrum"]
    }
    
    text_lower = text.lower()
    return [skill for _, skills in skill_keywords.items() for skill in skills if skill.lower() in text_lower]

@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):
    tech_skills = [
        "Python", "Java", "JavaScript", "SQL", "HTML", "CSS", "React", "Angular", "Machine Learning", "AWS",
        "Azure", "Docker", "MySQL", "MongoDB", "Project Management", "Agile", "Leadership", "Git", "DevOps"
    ]
    
    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
    matching_skills = [skill for skill in required_skills if skill in skills_mentioned]
    skill_match = len(matching_skills) / len(required_skills) if required_skills else 0
    
    # 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
    exp_match_ratio = min(1.0, years_experience / max(1, years_required)) if years_required > 0 else 0.5
    title_words = [w for w in job_title.lower().split() if len(w) > 3]
    title_match = sum(1 for w in title_words if w in resume_summary.lower()) / len(title_words) if title_words else 0
    
    # Final scores
    skill_score = min(2, skill_match * 3)
    exp_score = min(2, exp_match_ratio * 2)
    title_score = min(2, title_match * 2)
    
    # 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
    weighted_score = (skill_score * 0.5) + (exp_score * 0.3) + (title_score * 0.2)
    fit_score = 2 if weighted_score >= 1.5 else (1 if weighted_score >= 0.8 else 0)
    
    # 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():
    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: "NO 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
                """)

# Run the main function
if __name__ == "__main__":
    main()