import os
import json
import numpy as np
if not hasattr(np, 'bool'):
    np.bool = bool
import requests
from pymongo import MongoClient
from dotenv import load_dotenv
from bson import ObjectId
import transformers
import re
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.metrics.pairwise import cosine_similarity as sklearn_cosine_similarity
import faiss
from sentence_transformers import SentenceTransformer, util
from flask import Flask, request, jsonify

# ========== Google Generative AI (Gemini) imports ==========
import google.generativeai as genai

# Load environment variables
load_dotenv()

# Get API keys from environment variables
GOOGLE_API_KEY = os.getenv('GOOGLE_API_KEY')
MONGO_URI = os.getenv('MONGO_URI')

# Configure the Gemini client with the API key
genai.configure(api_key=GOOGLE_API_KEY)

# Connect to MongoDB
try:
    mongo_client = MongoClient(MONGO_URI)
    db = mongo_client["resume_database"]
    resumes_collection = db["resumes"]
    jobs_collection = db["jobs"]
    grouped_candidates_collection = db["grouped_candidates"]
    print("✅ Connected to MongoDB successfully.")
except Exception as e:
    raise Exception(f"❌ MongoDB connection failed: {str(e)}")

# Create Flask app
app = Flask(__name__)

# =============================================================================
# Revised Evaluation Rubric for Accurate, Job-Specific Scoring (Total 100)
# =============================================================================
NEW_RUBRIC = """
You are an expert resume evaluator and technical recruiter. Evaluate the candidate's resume against the job description with extreme precision, and deduct points aggressively for any misalignment. Consider the resume a poor match if it does not include key skills, relevant work experience, or projects that demonstrate a close fit with the job description. Use the following criteria to assign an exact score out of 100:

1. Skills (25 pts):
   - Direct match with required technical skills: up to 12 pts. Deduct points sharply for missing or weak skills.
   - Soft skills alignment: up to 5 pts. Deduct if soft skills are not clearly demonstrated.
   - Relevant years of experience: up to 8 pts. Deduct proportionally if experience is insufficient.

2. Work Experience (25 pts):
   - Relevance of roles and industry: up to 12 pts. Deduct heavily for roles not matching the job requirements.
   - Impact, achievements, and career progression: up to 13 pts. Deduct if achievements are unquantifiable or progression is unclear.

3. Project Relevance (30 pts):
   - Applicability to job, technical depth, deployment status, and innovation: up to 30 pts. Deduct sharply if projects lack demonstrable outcomes or technical complexity.

4. Education & Certifications (15 pts):
   - Alignment of education with job requirements: up to 10 pts.
   - Relevant certifications: up to 5 pts. Deduct for missing or irrelevant certifications.

5. Presentation & Clarity (5 pts):
   - Formatting, clarity, conciseness, and professionalism: 5 pts. Deduct for errors, inconsistencies, or unclear presentation.

Return only valid JSON with the following keys:
{
    "overall_score": "XX/100",
    "score_breakdown": {
        "skills_match": "XX/25",
        "work_experience": "XX/25",
        "project_relevance": "XX/30",
        "education_certifications": "XX/15",
        "presentation_clarity": "XX/5"
    },
    "key_matching_skills": ["skill1", "skill2"],
    "missing_skills": ["skill3", "skill4"],
    "strengths": "Specific, evidence-based strengths with examples",
    "weaknesses": "Concrete gaps or shortcomings with specific examples",
    "notable_projects": [
        {
            "title": "Project 1",
            "relevance_score": "XX/30",
            "reason": "Why this project is relevant or not"
        }
    ],
    "gaps": [
        "Specific gap 1 with evidence",
        "Specific gap 2 with evidence"
    ],
    "recommendation": "One of: Strong Reject, Reject, Consider with Reservations, Interview, Strong Recommendation"
}
Be highly critical and deduct points aggressively for any deviation from the ideal candidate profile.
"""

# =============================================================================
# Text Cleaning Helper Function
# =============================================================================
def clean_text(text, extra_stopwords=None):
    """
    Clean the input text by:
    - Converting to lowercase.
    - Removing punctuation.
    - Removing extra unwanted words using a custom stopword list.
    """
    text = text.lower()
    text = re.sub(r'[^\w\s]', '', text)
    stopwords = {'the', 'and', 'is', 'in', 'at', 'of', 'a', 'an', 'to', 'for', 'with', 'on', 'by'}
    if extra_stopwords:
        stopwords.update(extra_stopwords)
    tokens = text.split()
    cleaned_tokens = [token for token in tokens if token not in stopwords]
    return " ".join(cleaned_tokens)

# =============================================================================
# FAISS and Embedding Helper Functions with Hybrid Score
# =============================================================================

# Initialize embedding model
MODEL_PATH = os.path.join(os.getcwd(), "models", "all-MiniLM-L6-v2")
if os.path.exists(MODEL_PATH):
    print(f"Loading model from local path: {MODEL_PATH}")
    embedding_model = SentenceTransformer(MODEL_PATH)
else:
    print("Local model not found, downloading from Hugging Face")
    embedding_model = SentenceTransformer('all-MiniLM-L6-v2')


def get_embedding(text, prefix="passage: ", normalize=True):
    formatted_text = f"{prefix}{text.strip()}"
    emb = embedding_model.encode(formatted_text, convert_to_numpy=True)
    if normalize:
        norm = np.linalg.norm(emb)
        if norm > 0:
            emb = emb / norm
    return emb

def build_faiss_index(embeddings, use_inner_product=True):
    dim = embeddings.shape[1]
    index = faiss.IndexFlatIP(dim) if use_inner_product else faiss.IndexFlatL2(dim)
    index.add(embeddings)
    return index

def compute_tfidf_similarity(job_text, resume_text):
    clean_job = clean_text(job_text)
    clean_resume = clean_text(resume_text)
    vectorizer = TfidfVectorizer(stop_words='english')
    tfidf_matrix = vectorizer.fit_transform([clean_job, clean_resume])
    cosine_sim = sklearn_cosine_similarity(tfidf_matrix[0:1], tfidf_matrix[1:2])[0][0]
    return cosine_sim

def compute_keyword_score(job_text, resume_text, keyword_list):
    clean_job = set(clean_text(job_text).split())
    clean_resume = set(clean_text(resume_text).split())
    match_count = sum(1 for kw in keyword_list if kw.lower() in clean_job and kw.lower() in clean_resume)
    return match_count / len(keyword_list) if keyword_list else 0

def compute_hybrid_score(embedding_sim, tfidf_sim, keyword_sim, llm_confidence, weights):
    return (weights['embedding'] * embedding_sim +
            weights['tfidf'] * tfidf_sim +
            weights['keyword'] * keyword_sim +
            weights['llm'] * llm_confidence)

# =============================================================================
# Resume Evaluation Function Using LLM (Gemini) and FAISS Similarity
# =============================================================================

gemini_model = genai.GenerativeModel(model_name="gemini-2.0-flash")

def is_resume_substantive(resume_text, min_word_count=50):
    text = resume_text.lower()
    words = text.split()
    if len(words) < min_word_count:
        print(f"⚠ Resume failed word count check: {len(words)} words (min {min_word_count} required)")
        return False
    return True

def evaluate_resume(resume_text, job_description, evaluation_rubric=NEW_RUBRIC):
    if not is_resume_substantive(resume_text):
        empty_result = {
            "overall_score": "0/100",
            "score_breakdown": {
                "skills_match": "0/25",
                "work_experience": "0/25",
                "project_relevance": "0/30",
                "education_certifications": "0/15",
                "presentation_clarity": "0/5"
            },
            "key_matching_skills": [],
            "missing_skills": [],
            "irrelevant_experience": "",
            "strengths": "Resume text is too short or lacks essential sections.",
            "weaknesses": "Insufficient or unstructured content provided in resume.",
            "notable_projects": [],
            "gaps": ["The resume has no substantive information."],
            "recommendation": "Reject",
            "numerical_score": 0
        }
        print("⚠ Resume did not pass the substantive content checks.")
        return json.dumps(empty_result)

    try:
        prompt = f"""
You are an expert resume evaluator and technical recruiter.
Below are the original resume text and job description, followed by Evaluation Criteria.
Be extremely critical. Deduct points aggressively if key skills, work experience, projects, or education do not match the job description.
Assign an exact score out of 100 (do not provide a generic score) and provide detailed evidence for each scoring category.

Original Resume Text:
{resume_text}

Original Job Description:
{job_description}

Evaluation Criteria:
{evaluation_rubric}

Return only valid JSON with the following keys:
overall_score, score_breakdown (skills_match, work_experience, project_relevance, education_certifications, presentation_clarity),
key_matching_skills, missing_skills, irrelevant_experience, strengths, weaknesses, notable_projects (list of objects with title, relevance_score, reason), gaps, recommendation.
"""
        response = gemini_model.generate_content(prompt)
        generated_text = response.text.strip() if response.text else ""
        if not generated_text:
            print("❌ No generated text found in the response from Gemini.")
            return "{}"
        json_start = generated_text.find('{')
        if json_start == -1:
            print(f"❌ No JSON found in the generated text: {generated_text}")
            return "{}"
        json_str = generated_text[json_start:].strip()
        brace_count = 0
        extracted_json = ""
        for i, char in enumerate(json_str):
            if char == '{':
                brace_count += 1
            elif char == '}':
                brace_count -= 1
                if brace_count == 0:
                    extracted_json = json_str[:i+1]
                    break
        return extracted_json
    except Exception as e:
        print(f"❌ Exception during evaluation: {e}")
        return "{}"

# =============================================================================
# Resume Processing & Candidate Grouping with FAISS Integration
# =============================================================================

from bson import ObjectId

def get_full_job_text(job_doc):
    """
    Concatenates all text fields from a job document into a single string.
    """
    if not job_doc:
        return "No description available."
    text_parts = []
    for key, value in job_doc.items():
        if isinstance(value, list):
            text_parts.append(" ".join(value))
        elif isinstance(value, str):
            text_parts.append(value)
    return " ".join(text_parts).strip()


def process_resumes(job_id_filter):
    try:
        # Retrieve the job document by _id instead of jobId.
        job_doc = jobs_collection.find_one({"_id": ObjectId(job_id_filter)})
        if job_doc:
            job_description = get_full_job_text(job_doc)
        else:
            job_description = "No description available."
        print(f"ℹ Using job description: {job_description}")

        resumes = list(resumes_collection.find({"jobId": job_id_filter}))
        print(f"📂 Found {len(resumes)} resumes to process for Job ID: {job_id_filter}.")

        resume_texts = []
        resume_ids = []
        resume_mapping = {}

        for resume in resumes:
            job_id = resume.get("jobId")
            if not job_id:
                print(f"⚠ Skipping resume (ID: {resume.get('_id')}) - Missing jobId.")
                continue

            resume_text = resume.get("resume_data", "")
            if isinstance(resume_text, dict):
                resume_text = json.dumps(resume_text)
            resume_text = resume_text.strip()
            if not resume_text:
                print(f"⚠ Skipping resume (ID: {resume.get('_id')}) - No resume text found.")
                continue

            resume_texts.append(resume_text)
            resume_ids.append(resume["_id"])
            resume_mapping[len(resume_texts)-1] = resume

        if not resume_texts:
            print("⚠ No new resumes to process.")
            return

        # Prepare keywords from the cleaned job description.
        job_keywords = list(set(clean_text(job_description).split()))

        # Compute embeddings with distinct prefixes and normalize them.
        job_embedding = get_embedding(job_description, prefix="query: ", normalize=True)
        resume_embeddings = np.array([get_embedding(text, prefix="passage: ", normalize=True) for text in resume_texts])
        index = build_faiss_index(resume_embeddings, use_inner_product=True)
        job_embedding_expanded = np.expand_dims(job_embedding, axis=0)
        similarities, indices = index.search(job_embedding_expanded, len(resume_texts))
        embedding_similarity_scores = [max(sim, 0) for sim in similarities[0]]

        # Adjusted weights: embedding and LLM have more influence.
        weights = {
            'embedding': 0.25,
            'tfidf': 0.25,
            'keyword': 0.15,
            'llm': 0.50
        }
        # Boost factor to calibrate final scores.
        boost_factor = 1.5

        for idx, resume_text in enumerate(resume_texts):
            embedding_sim = float(embedding_similarity_scores[idx])
            tfidf_sim = compute_tfidf_similarity(job_description, resume_text)
            keyword_sim = compute_keyword_score(job_description, resume_text, job_keywords)
            analysis_result_text = evaluate_resume(resume_text, job_description)
            try:
                analysis_result = json.loads(analysis_result_text)
            except json.JSONDecodeError as e:
                print(f"❌ Error parsing analysis result for resume ID {resume_ids[idx]}: {e}")
                analysis_result = {
                    "overall_score": "XX/100",
                    "score_breakdown": {
                        "skills_match": "XX/25",
                        "work_experience": "XX/25",
                        "project_relevance": "XX/30",
                        "education_certifications": "XX/15",
                        "presentation_clarity": "XX/5"
                    },
                    "strengths": "Unable to properly evaluate - parsing error",
                    "weaknesses": "System could not properly analyze this resume",
                    "notable_projects": [],
                    "gaps": ["Analysis failed - please review manually"],
                    "recommendation": "Consider with Reservations",
                }
            try:
                score_string = analysis_result.get("overall_score", "0/100")
                score_parts = score_string.split('/')
                llm_score = int(score_parts[0]) if len(score_parts) >= 1 else 0
            except (ValueError, TypeError):
                llm_score = 0
            llm_confidence = llm_score / 100.0

            # Compute the hybrid score using the weighted sum of the four components.
            hybrid_score = compute_hybrid_score(embedding_sim, tfidf_sim, keyword_sim, llm_confidence, weights)

            # If LLM confidence (in percentage) is less than 50, do not apply the boost factor.
            if llm_score < 50:
                final_score = int(hybrid_score * 100)
            else:
                final_score = min(int(hybrid_score * boost_factor * 100), 100)

            analysis_result["embedding_similarity"] = round(embedding_sim, 3)
            analysis_result["tfidf_similarity"] = round(tfidf_sim, 3)
            analysis_result["keyword_similarity"] = round(keyword_sim, 3)
            analysis_result["llm_confidence"] = f"{llm_score}/100"
            analysis_result["overall_score"] = f"{final_score}/100"
            analysis_result["numerical_score"] = final_score

            resumes_collection.update_one(
                {"_id": resume_ids[idx]},
                {"$set": {"analysis_result": analysis_result}}
            )
            print(f"✅ Processed resume (ID: {resume_ids[idx]}) with Hybrid Score: {analysis_result.get('overall_score', 'N/A')} (Embedding: {round(embedding_sim, 3)}, TF-IDF: {round(tfidf_sim, 3)}, Keyword: {round(keyword_sim, 3)})")

        print("🎯 All resumes processed successfully.")
        return True
    except Exception as e:
        print(f"❌ Error processing resumes: {str(e)}")
        import traceback
        print(traceback.format_exc())
        return False

def group_and_store_candidates(job_id_filter):
    try:
        pipeline = [
            {"$match": {"jobId": job_id_filter}},
            {
                "$group": {
                    "_id": {
                        "jobId": "$jobId",
                        "jobTitle": "$jobTitle"
                    },
                    "candidates": {
                        "$push": {
                            "candidate_id": "$_id",
                            "candidate_name": "$formName",
                            "candidate_email": "$formEmail",
                            "candidate_phone": "$formPhone",
                            "resume_data": "$resume_data",
                            "analysis_result": "$analysis_result"
                        }
                    }
                }
            }
        ]

        grouped_resumes = resumes_collection.aggregate(pipeline)
        job_descriptions = {}
        for job in jobs_collection.find({"jobId": job_id_filter}):
            job_id = job.get("jobId")
            if job_id:
                job_title = job.get("title", "No Title Provided")
                short_desc = job.get("shortDescription", "")
                full_desc = job.get("fullDescription", "")
                responsibilities = " ".join(job.get("responsibilities", []))
                requirements = " ".join(job.get("requirements", []))
                core_expertise = job.get("coreExpertise", "")
                full_job_description = (
                    f"{job_title}. {short_desc} {full_desc} "
                    f"Responsibilities: {responsibilities}. "
                    f"Requirements: {requirements}. "
                    f"Core Expertise: {core_expertise}."
                )
                job_descriptions[job_id] = full_job_description

        grouped_candidates_collection.delete_many({"jobId": job_id_filter})

        for group in grouped_resumes:
            _id = group.get("_id", {})
            job_id = _id.get("jobId")
            job_title = _id.get("jobTitle", "No Title Provided")
            if not job_id:
                print(f"⚠ Skipping grouped set without jobId: {group}")
                continue

            candidates = group["candidates"]
            for candidate in candidates:
                analysis_result = candidate.get("analysis_result", {})
                if isinstance(analysis_result, str):
                    try:
                        analysis_result = json.loads(analysis_result)
                        candidate["analysis_result"] = analysis_result
                    except (json.JSONDecodeError, TypeError):
                        analysis_result = {}
                if not analysis_result.get("numerical_score"):
                    try:
                        score_string = analysis_result.get("overall_score", "0/100")
                        score_parts = score_string.split('/')
                        numerical_score = int(score_parts[0]) if len(score_parts) >= 1 else 0
                        analysis_result["numerical_score"] = numerical_score
                    except (ValueError, TypeError, IndexError):
                        analysis_result["numerical_score"] = 0

            sorted_candidates = sorted(
                candidates,
                key=lambda x: x.get("analysis_result", {}).get("numerical_score", 0),
                reverse=True
            )

            recommendation_tiers = {
                "Strong Recommendation": [],
                "Interview": [],
                "Consider with Reservations": [],
                "Reject": [],
                "Strong Reject": [],
                "Uncategorized": []
            }

            for candidate in sorted_candidates:
                recommendation = candidate.get("analysis_result", {}).get("recommendation", "Uncategorized")
                if recommendation in recommendation_tiers:
                    recommendation_tiers[recommendation].append(candidate)
                else:
                    recommendation_tiers["Uncategorized"].append(candidate)

            tiered_candidates = []
            for tier, tier_candidates in recommendation_tiers.items():
                tier_candidates.sort(
                    key=lambda x: x.get("analysis_result", {}).get("numerical_score", 0),
                    reverse=True
                )
                tiered_candidates.extend(tier_candidates)

            grouped_candidates_collection.update_one(
                {"jobId": job_id},
                {
                    "$set": {
                        "jobId": job_id,
                        "jobTitle": job_title,
                        "candidates": sorted_candidates,
                        "tiered_candidates": tiered_candidates,
                        "candidate_tiers": {
                            tier: len(candidates) for tier, candidates in recommendation_tiers.items() if candidates
                        },
                        "total_candidates": len(candidates),
                        "top_candidates": sorted_candidates[:5] if len(sorted_candidates) >= 5 else sorted_candidates
                    }
                },
                upsert=True
            )

            print(f"✅ Grouped {len(candidates)} candidates for Job: {job_title} (Job ID: {job_id})")

        print("🎯 All grouped candidates stored successfully.")
        return True
    except Exception as e:
        print(f"❌ Error grouping candidates: {str(e)}")
        import traceback
        print(traceback.format_exc())
        return False

# API endpoints
@app.route('/api/process-resumes', methods=['POST'])
def api_process_resumes():
    data = request.json
    job_id = data.get('job_id')
    
    if not job_id:
        return jsonify({"status": "error", "message": "Job ID is required"}), 400
    
    process_success = process_resumes(job_id)
    grouping_success = group_and_store_candidates(job_id)
    
    if process_success and grouping_success:
        return jsonify({
            "status": "success",
            "message": f"Resumes processed successfully for job ID: {job_id}"
        })
    else:
        return jsonify({
            "status": "error",
            "message": f"Error processing resumes for job ID: {job_id}"
        }), 500

if __name__ == "__main__":
    app.run(debug=True, host='0.0.0.0', port=7860)