import base64
import io
import os
import re
import traceback
from datetime import datetime, timezone

import numpy as np
from dotenv import load_dotenv
from fastapi import FastAPI, File, Form, HTTPException, UploadFile
from fastapi.middleware.cors import CORSMiddleware
from insightface.app import FaceAnalysis
from PIL import Image
from pydantic import BaseModel
from supabase import create_client

load_dotenv()

SUPABASE_URL = os.environ["SUPABASE_URL"]
SUPABASE_SERVICE_KEY = os.environ["SUPABASE_SERVICE_KEY"]
ALLOWED_ORIGIN = os.environ.get("ALLOWED_ORIGIN", "*")
FACE_MATCH_THRESHOLD = 0.65  # cosine distance (lower = more similar; 0.65 is lenient for webcam-vs-photo variation)

supabase = create_client(SUPABASE_URL, SUPABASE_SERVICE_KEY)


def get_client():
    """Return a fresh Supabase client to avoid stale HTTP/2 connections."""
    return create_client(SUPABASE_URL, SUPABASE_SERVICE_KEY)

# Load InsightFace model once at startup
fa = FaceAnalysis(name="buffalo_sc", providers=["CPUExecutionProvider"])
fa.prepare(ctx_id=-1, det_size=(320, 320))

app = FastAPI(title="Facial Attendance API")

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)


# ─── helpers ──────────────────────────────────────────────────────────────────

def image_from_bytes(data: bytes) -> np.ndarray:
    img = Image.open(io.BytesIO(data)).convert("RGB")
    arr = np.array(img)
    # InsightFace expects BGR (OpenCV convention); PIL gives RGB
    return arr[:, :, ::-1]


def image_from_base64(b64: str) -> np.ndarray:
    if "," in b64:
        b64 = b64.split(",", 1)[1]
    return image_from_bytes(base64.b64decode(b64))


def encode_face(img_array: np.ndarray) -> list[float]:
    """Return the L2-normalised 512-dim embedding of the largest detected face."""
    faces = fa.get(img_array)
    if not faces:
        return []
    # Pick the largest face by bounding-box area
    face = max(faces, key=lambda f: (f.bbox[2] - f.bbox[0]) * (f.bbox[3] - f.bbox[1]))
    return face.normed_embedding.tolist()


def parse_iso_dt(ts: str) -> datetime:
    """Parse ISO timestamp from Supabase, handling non-6-digit microseconds (Python 3.10 compat)."""
    # Python 3.10 fromisoformat requires exactly 6 digits for fractional seconds when timezone present
    # Supabase may return 5 digits e.g. "14:32:02.53557+00:00" — pad to 6: "14:32:02.535570+00:00"
    ts = re.sub(r'\.(\d+)([+-])', lambda m: f'.{m.group(1)[:6]:0<6}{m.group(2)}', ts)
    return datetime.fromisoformat(ts)


def load_encodings_for_admin(admin_id: str | None) -> list[dict]:
    """Return employees scoped to one admin, or all employees if no admin_id given."""
    client = get_client()
    query = client.table("employees").select("id, name, email, face_encoding")
    if admin_id:
        query = query.eq("admin_id", admin_id)
    return query.execute().data or []


def best_match(unknown: list[float], employees: list[dict]) -> tuple[dict | None, float]:
    """Cosine distance match. Returns (best_employee, best_distance)."""
    if not employees:
        return None, float("inf")
    unknown_arr = np.array(unknown)
    best_emp, best_dist = None, float("inf")
    for emp in employees:
        known = np.array(emp["face_encoding"])
        dist = 1.0 - float(np.dot(unknown_arr, known))  # embeddings are L2-normalised
        if dist < best_dist:
            best_dist = dist
            best_emp = emp
    if best_dist <= FACE_MATCH_THRESHOLD:
        return best_emp, best_dist
    return None, best_dist


# ─── routes ───────────────────────────────────────────────────────────────────

@app.get("/debug/employees")
def debug_employees(admin_id: str | None = None):
    """Debug: return employee count and names for given admin_id."""
    try:
        client = get_client()
        query = client.table("employees").select("id, name, admin_id")
        if admin_id:
            query = query.eq("admin_id", admin_id)
        data = query.execute().data or []
        return {"count": len(data), "employees": data}
    except Exception as e:
        return {"error": traceback.format_exc()}


@app.get("/debug/full-test")
def debug_full_test(employee_id: str, admin_id: str | None = None):
    """Debug: simulate the full clock DB path for a given employee_id."""
    try:
        client = get_client()
        # 1. Load employees
        emps = load_encodings_for_admin(admin_id)
        emp = next((e for e in emps if e["id"] == employee_id), None)
        if not emp:
            return {"step": "load_employees", "error": "employee not found", "count": len(emps)}

        # 2. Attendance SELECT
        today = datetime.now(timezone.utc).date().isoformat()
        rows = (
            client.table("attendance")
            .select("id, check_in, check_out, hours_worked")
            .eq("employee_id", employee_id)
            .eq("date", today)
            .execute()
        )
        record = rows.data[0] if rows.data else None

        # 3. Datetime parse test
        dt_parse_ok = True
        if record and record.get("check_in"):
            try:
                check_in_dt = parse_iso_dt(record["check_in"])
                hours = round((datetime.now(timezone.utc) - check_in_dt).total_seconds() / 3600, 2)
            except Exception as e:
                dt_parse_ok = False
                return {"step": "datetime_parse", "error": str(e), "check_in": record["check_in"]}

        return {
            "ok": True,
            "employee": emp["name"],
            "today": today,
            "attendance_record": record,
            "datetime_parse_ok": dt_parse_ok,
            "would_action": "sign_out" if record and record.get("check_out") is None else
                           "already_complete" if record else "sign_in"
        }
    except Exception as e:
        return {"error": traceback.format_exc()}

@app.get("/health")
def health():
    return {"status": "ok", "version": "2"}


@app.post("/register")
async def register(
    name: str = Form(...),
    email: str = Form(...),
    department: str = Form(""),
    admin_id: str = Form(""),
    photo: UploadFile = File(...),
):
    if not admin_id:
        raise HTTPException(status_code=400, detail="admin_id is required.")

    try:
        photo_bytes = await photo.read()
        img = image_from_bytes(photo_bytes)
        encoding = encode_face(img)
    except Exception as e:
        raise HTTPException(status_code=400, detail=f"Image processing error: {traceback.format_exc()}")

    if not encoding:
        raise HTTPException(status_code=400, detail="No face detected in the photo. Please retake.")

    try:
        client = get_client()
        storage_path = f"{admin_id}/{email.replace('@', '_').replace('.', '_')}.jpg"
        client.storage.from_("employee-photos").upload(
            path=storage_path,
            file=photo_bytes,
            file_options={"content-type": "image/jpeg", "upsert": "true"},
        )
        photo_url = client.storage.from_("employee-photos").get_public_url(storage_path)

        client.table("employees").upsert(
            {
                "name": name,
                "email": email,
                "department": department,
                "photo_url": photo_url,
                "face_encoding": encoding,
                "admin_id": admin_id,
            },
            on_conflict="email",
        ).execute()
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Database error: {traceback.format_exc()}")

    return {"success": True, "message": f"{name} registered successfully."}


class ClockRequest(BaseModel):
    image: str
    admin_id: str | None = None


@app.post("/clock")
def clock(req: ClockRequest):
    try:
        img = image_from_base64(req.image)
        encoding = encode_face(img)
    except Exception as e:
        return {"status": "error", "detail": traceback.format_exc()}

    if not encoding:
        return {"status": "no_face"}

    try:
        employees = load_encodings_for_admin(req.admin_id)
    except Exception:
        return {"status": "error", "detail": traceback.format_exc()}

    match, best_dist = best_match(encoding, employees)
    if not match:
        return {"status": "not_registered", "_debug_emp_count": len(employees), "_debug_best_dist": round(best_dist, 4)}

    employee_id = match["id"]
    name = match["name"]
    today = datetime.now(timezone.utc).date().isoformat()
    now_iso = datetime.now(timezone.utc).isoformat()

    try:
        client = get_client()
        rows = (
            client.table("attendance")
            .select("id, check_in, check_out, hours_worked")
            .eq("employee_id", employee_id)
            .eq("date", today)
            .execute()
        )
        record = rows.data[0] if rows.data else None

        if record is None:
            client.table("attendance").insert(
                {"employee_id": employee_id, "date": today, "check_in": now_iso, "status": "present"}
            ).execute()
            return {"status": "matched", "action": "signed_in", "name": name, "time": now_iso}

        if record["check_out"] is None:
            check_in_dt = parse_iso_dt(record["check_in"])
            check_out_dt = datetime.now(timezone.utc)
            hours = round((check_out_dt - check_in_dt).total_seconds() / 3600, 2)
            client.table("attendance").update(
                {"check_out": now_iso, "hours_worked": hours, "status": "present"}
            ).eq("id", record["id"]).execute()
            return {"status": "matched", "action": "signed_out", "name": name, "time": now_iso, "hours_worked": hours}

        return {"status": "matched", "action": "already_complete", "name": name, "hours_worked": record["hours_worked"]}

    except Exception as e:
        return {"status": "error", "detail": traceback.format_exc()}