import io
import os
import requests
import pandas as pd
import logging

from fastapi import FastAPI, UploadFile, File, HTTPException
from pypdf import PdfReader
from docx import Document

# =========================
# LOGGING
# =========================
logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(message)s",
)
logger = logging.getLogger(__name__)

# =========================
# ENV
# =========================
N8N_WEBHOOK_URL = os.getenv("N8N_WEBHOOK_URL")

if not N8N_WEBHOOK_URL:
    raise RuntimeError("❌ N8N_WEBHOOK_URL not set")

logger.info(f"✅ N8N_WEBHOOK_URL = {N8N_WEBHOOK_URL}")

# =========================
# APP
# =========================
app = FastAPI(title="HF Resume Ingestion Service")

# =========================
# UTILITIES
# =========================

def normalize_resume_url(url: str) -> str:
    """
    Convert Google Drive share links to direct download URLs.
    """
    if "drive.google.com" in url and "/file/d/" in url:
        file_id = url.split("/file/d/")[1].split("/")[0]
        return f"https://drive.google.com/uc?export=download&id={file_id}"
    return url


def download_file(url: str) -> bytes:
    url = normalize_resume_url(url)
    logger.info(f"⬇️ Downloading resume (normalized): {url}")

    r = requests.get(url, timeout=30)
    r.raise_for_status()
    return r.content


def extract_text_from_pdf(data: bytes) -> str:
    reader = PdfReader(io.BytesIO(data))
    return "\n".join(page.extract_text() or "" for page in reader.pages)


def extract_text_from_docx(data: bytes) -> str:
    doc = Document(io.BytesIO(data))
    return "\n".join(p.text for p in doc.paragraphs)


def extract_resume_text(resume_url: str) -> str:
    """
    Detect file type by content signature, not URL.
    """
    data = download_file(resume_url)

    # PDF signature
    if data[:4] == b"%PDF":
        return extract_text_from_pdf(data)

    # DOCX signature (ZIP)
    if data[:2] == b"PK":
        return extract_text_from_docx(data)

    raise ValueError("Unsupported resume format (only pdf/docx)")


def basic_skill_extraction(text: str) -> list[str]:
    """
    Lightweight heuristic skill extraction (NO AI evaluation here).
    """
    COMMON_SKILLS = [
        "python", "java", "javascript", "react", "node",
        "firebase", "sql", "mongodb", "docker",
        "aws", "git", "linux"
    ]
    text_lower = text.lower()
    return sorted({skill for skill in COMMON_SKILLS if skill in text_lower})


def send_to_n8n(payload: dict):
    logger.info("➡️ Sending payload to n8n")
    logger.info(payload)

    try:
        r = requests.post(
            N8N_WEBHOOK_URL,
            json=payload,
            timeout=15,
        )
        logger.info(f"⬅️ n8n response status: {r.status_code}")
        logger.info(f"⬅️ n8n response body: {r.text}")

        r.raise_for_status()

    except requests.exceptions.RequestException as e:
        logger.error("❌ Failed to send data to n8n")
        raise RuntimeError(str(e))

# =========================
# API
# =========================

@app.post("/upload-excel")
async def upload_excel(file: UploadFile = File(...)):
    logger.info(f"📂 Received file: {file.filename}")

    if not file.filename.endswith(".xlsx"):
        raise HTTPException(status_code=400, detail="Only .xlsx supported")

    # FIXED: wrap bytes in BytesIO
    content = await file.read()
    df = pd.read_excel(io.BytesIO(content))

    required_columns = {"name", "email", "phone", "jobId", "resume_url"}
    if not required_columns.issubset(df.columns):
        raise HTTPException(
            status_code=400,
            detail=f"Invalid Excel format. Required columns: {required_columns}",
        )

    report = []

    for index, row in df.iterrows():
        email = str(row.get("email"))
        logger.info(f"👤 Processing row {index + 1}: {email}")

        try:
            resume_text = extract_resume_text(str(row["resume_url"]))
            skills = basic_skill_extraction(resume_text)

            payload = {
                "candidate": {
                    "name": str(row["name"]),
                    "email": email,
                    "phone": str(row["phone"]),
                    "jobId": str(row["jobId"]),
                },
                "parsed": {
                    "skills": skills,
                    "resumeText": resume_text[:6000],  # safety cap
                },
            }

            send_to_n8n(payload)

            report.append({
                "email": email,
                "status": "sent",
            })

        except Exception as e:
            logger.error(f"❌ Error processing {email}: {e}")

            report.append({
                "email": email,
                "status": "failed",
                "error": str(e),
            })

    return {
        "total": len(df),
        "processed": len(report),
        "results": report,
    }