import os
import tempfile
import re
import streamlit as st
import docx
import textract
from sentence_transformers import SentenceTransformer, util
from transformers import pipeline

#####################################
# Function: Extract Text from File
#####################################
def extract_text_from_file(file_obj):
    """
    Extract text from .doc and .docx 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])
        except Exception as e:
            text = f"Error processing DOCX file: {e}"
    elif ext == ".doc":
        try:
            # textract requires a file name; save the file temporarily.
            with tempfile.NamedTemporaryFile(delete=False, suffix=".doc") as tmp:
                tmp.write(file_obj.read())
                tmp.flush()
                tmp_filename = tmp.name
            text = textract.process(tmp_filename).decode("utf-8")
        except Exception as e:
            text = f"Error processing DOC file: {e}"
        finally:
            try:
                os.remove(tmp_filename)
            except Exception:
                pass
    else:
        text = "Unsupported file type."
    return text

#####################################
# Function: Summarize Resume Text using a Transformer Model
#####################################
@st.cache_resource(show_spinner=False)
def load_summarizer():
    """
    Loads the summarization pipeline using a transformer model.
    We use the model "ainize/bart-base-cnn" for summarization.
    """
    return pipeline("summarization", model="spursyy/mT5_multilingual_XLSum_rust")

def summarize_resume_text(resume_text):
    """
    Generates a concise summary of the resume text using the summarization model.
    If the resume text is very long, we trim it to avoid hitting the model's maximum input size.
    """
    summarizer = load_summarizer()
    # In case the resume text is too long, we trim it.
    max_input_length = 1024  # adjust as needed
    if len(resume_text) > max_input_length:
        resume_text = resume_text[:max_input_length]
    # The summarization pipeline returns a list of summaries.
    summary_result = summarizer(resume_text, max_length=150, min_length=40, do_sample=False)
    candidate_summary = summary_result[0]['summary_text']
    return candidate_summary

#####################################
# Function: Compare Candidate Summary to Company Prompt
#####################################
def compute_suitability(candidate_summary, company_prompt, model):
    """
    Compute the cosine similarity between candidate summary and company prompt embeddings.
    Returns a score in the range [0, 1].
    """
    candidate_embed = model.encode(candidate_summary, convert_to_tensor=True)
    company_embed = model.encode(company_prompt, convert_to_tensor=True)
    cosine_sim = util.cos_sim(candidate_embed, company_embed)
    score = float(cosine_sim.item())
    return score

#####################################
# Main Resume Processing Logic
#####################################
def process_resume(file_obj):
    """
    Extracts text from the uploaded file and then generates a summary
    using a text summarization model.
    """
    resume_text = extract_text_from_file(file_obj)
    candidate_summary = summarize_resume_text(resume_text)
    return candidate_summary

#####################################
# Load the Sentence-BERT Model (Semantic Similarity Model)
#####################################
@st.cache_resource(show_spinner=False)
def load_sbert_model():
    # This loads the Sentence-BERT model "all-MiniLM-L6-v2"
    return SentenceTransformer("sentence-transformers/all-MiniLM-L6-v2")

# Load Sentence-BERT model for computing semantic similarity.
sbert_model = load_sbert_model()

#####################################
# Streamlit Interface
#####################################
st.title("Resume Analyzer and Company Suitability Checker")
st.markdown(
    """
Upload your resume file in **.doc** or **.docx** format. The app performs the following tasks:
1. Extracts text from the resume.
2. Uses a transformer-based text summarization model (**ainize/bart-base-cnn**) to generate a concise candidate summary.
3. Compares the candidate summary with a company profile (using Sentence-BERT) to produce a suitability score.
"""
)

# File uploader for resume
uploaded_file = st.file_uploader("Upload Resume", type=["doc", "docx"])

# Button to process the resume and store the summary in session state.
if st.button("Process Resume"):
    if uploaded_file is None:
        st.error("Please upload a resume file first.")
    else:
        with st.spinner("Processing resume..."):
            candidate_summary = process_resume(uploaded_file)
            st.session_state["candidate_summary"] = candidate_summary
        st.subheader("Candidate Summary")
        st.markdown(candidate_summary)

# Pre-defined company prompt for Google LLC.
default_company_prompt = (
    "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."
)

# Company prompt text area.
company_prompt = st.text_area(
    "Enter company details:",
    value=default_company_prompt,
    height=150,
)

# Button to compute the suitability score.
if st.button("Compute Suitability Score"):
    if "candidate_summary" not in st.session_state:
        st.error("Please process the resume first!")
    else:
        candidate_summary = st.session_state["candidate_summary"]
        if candidate_summary.strip() == "":
            st.error("Candidate summary is empty; please check your resume file.")
        elif company_prompt.strip() == "":
            st.error("Please enter the company information.")
        else:
            with st.spinner("Computing suitability score..."):
                score = compute_suitability(candidate_summary, company_prompt, sbert_model)
            st.success(f"Suitability Score: {score:.2f} (range 0 to 1)")