"""
GAIS Data Import Module — loads Edubase school data into Supabase gais_schools table.
Run via: python3 main.py --mode gais-data
Prereq: apply PLANNING/migrations/001_gais_seed.sql to Supabase first.
"""
import os
import csv
import time
from typing import Dict, Any, List, Optional
from modules.logger_tool import initialise_logger

logger = initialise_logger(__name__, os.getenv("LOG_LEVEL"), os.getenv("LOG_PATH"), 'default', True)

IMPORT_DIR = os.path.join(os.path.dirname(__file__), "import")
EDUBASE_FILE = os.path.join(IMPORT_DIR, "edubasealldata20250828.csv")

BATCH_SIZE = 500


def _parse_date(val: str) -> Optional[str]:
    """Convert DD-MM-YYYY or DD/MM/YYYY to YYYY-MM-DD, return None if empty."""
    val = val.strip()
    if not val:
        return None
    for sep in ("-", "/"):
        if sep in val:
            parts = val.split(sep)
            if len(parts) == 3 and len(parts[2]) == 4:
                return f"{parts[2]}-{parts[1].zfill(2)}-{parts[0].zfill(2)}"
    return None


def _parse_int(val: str) -> Optional[int]:
    val = val.strip()
    if not val:
        return None
    try:
        return int(val)
    except ValueError:
        return None


def _row_to_school(row: Dict[str, str]) -> Dict[str, Any]:
    return {
        "urn": row.get("URN", "").strip(),
        "name": row.get("EstablishmentName", "").strip(),
        "status": row.get("EstablishmentStatus (name)", "").strip() or None,
        "phase": row.get("PhaseOfEducation (name)", "").strip() or None,
        "type": row.get("TypeOfEstablishment (name)", "").strip() or None,
        "type_group": row.get("EstablishmentTypeGroup (name)", "").strip() or None,
        "street": row.get("Street", "").strip() or None,
        "locality": row.get("Locality", "").strip() or None,
        "town": row.get("Town", "").strip() or None,
        "county": row.get("County (name)", "").strip() or None,
        "postcode": row.get("Postcode", "").strip() or None,
        "website": row.get("SchoolWebsite", "").strip() or None,
        "telephone": row.get("TelephoneNum", "").strip() or None,
        "head_title": row.get("HeadTitle (name)", "").strip() or None,
        "head_first_name": row.get("HeadFirstName", "").strip() or None,
        "head_last_name": row.get("HeadLastName", "").strip() or None,
        "la_code": row.get("LA (code)", "").strip() or None,
        "la_name": row.get("LA (name)", "").strip() or None,
        "number_of_pupils": _parse_int(row.get("NumberOfPupils", "")),
        "open_date": _parse_date(row.get("OpenDate", "")),
        "close_date": _parse_date(row.get("CloseDate", "")),
        "gender": row.get("Gender (name)", "").strip() or None,
        "religious_character": row.get("ReligiousCharacter (name)", "").strip() or None,
        "region": row.get("GOR (name)", "").strip() or None,
    }


def _upsert_batch(supabase_client, table: str, batch: List[Dict[str, Any]], retries: int = 3) -> bool:
    for attempt in range(retries):
        try:
            supabase_client.table(table).upsert(batch, on_conflict="urn" if table == "gais_schools" else "code").execute()
            return True
        except Exception as e:
            logger.warning(f"Upsert attempt {attempt + 1} failed for {table}: {e}")
            time.sleep(2 ** attempt)
    logger.error(f"All {retries} upsert attempts failed for {table}")
    return False


def import_gais_data() -> Dict[str, Any]:
    """Load Edubase CSV into Supabase gais_schools + gais_local_authorities tables.
    Two-pass: collect LAs and schools, insert LAs first (FK parent), then schools.
    """
    from modules.database.supabase.utils.client import SupabaseServiceRoleClient
    sb = SupabaseServiceRoleClient()
    client = sb.supabase

    if not os.path.exists(EDUBASE_FILE):
        return {"success": False, "message": f"CSV not found: {EDUBASE_FILE}"}

    logger.info(f"Loading GAIS data from {EDUBASE_FILE}")

    la_map: Dict[str, str] = {}       # code → name
    schools: List[Dict[str, Any]] = []

    # Pass 1: read everything into memory
    with open(EDUBASE_FILE, encoding="cp1252", errors="replace") as f:
        reader = csv.DictReader(f)
        for row in reader:
            urn = row.get("URN", "").strip()
            if not urn:
                continue
            la_code = row.get("LA (code)", "").strip()
            la_name = row.get("LA (name)", "").strip()
            if la_code and la_code not in la_map:
                la_map[la_code] = la_name
            schools.append(_row_to_school(row))

    logger.info(f"Read {len(schools)} schools and {len(la_map)} LAs from CSV")

    # Insert LAs first (FK parent)
    la_batch = [{"code": code, "name": name} for code, name in la_map.items()]
    la_inserted = 0
    for i in range(0, len(la_batch), BATCH_SIZE):
        chunk = la_batch[i:i + BATCH_SIZE]
        if _upsert_batch(client, "gais_local_authorities", chunk):
            la_inserted += len(chunk)
    logger.info(f"Inserted {la_inserted} local authorities")

    # Insert schools in batches
    total_schools = 0
    total_errors = 0
    for i in range(0, len(schools), BATCH_SIZE):
        batch = schools[i:i + BATCH_SIZE]
        if _upsert_batch(client, "gais_schools", batch):
            total_schools += len(batch)
            if total_schools % 5000 == 0:
                logger.info(f"Inserted {total_schools} schools so far...")
        else:
            total_errors += len(batch)

    logger.info(f"GAIS import complete: {total_schools} schools, {la_inserted} LAs, {total_errors} errors")
    return {
        "success": total_errors == 0,
        "schools_inserted": total_schools,
        "las_inserted": la_inserted,
        "errors": total_errors,
    }