"""
Sheet management — Python port of sheet_helpers.php.
File-based JSON storage, one metadata file + one data file per sheet.
"""

import json
import logging
import os
import re
import time
import random
from datetime import datetime, timezone
from typing import List, Optional, Dict

from ..config_runtime import server_config

logger = logging.getLogger(__name__)

METADATA_FILE = os.path.join(server_config.DATA_DIR, 'sheets_metadata.json')


def _safe_user(user_id: str) -> str:
    """Sanitise user_id for use in filenames."""
    return re.sub(r'[^a-zA-Z0-9_\-]', '_', user_id)


def _sheet_path(user_id: str, sheet_id: str) -> str:
    return os.path.join(server_config.SHEETS_DIR, f"{_safe_user(user_id)}_{sheet_id}.json")


def _load_metadata() -> Dict:
    if not os.path.exists(METADATA_FILE):
        return {}
    try:
        with open(METADATA_FILE, 'r') as f:
            return json.load(f)
    except Exception:
        return {}


def _save_metadata(meta: Dict):
    with open(METADATA_FILE, 'w') as f:
        json.dump(meta, f, indent=2)


def get_user_sheets(user_id: str) -> List[Dict]:
    meta = _load_metadata()
    return meta.get(user_id, [])


def create_sheet(user_id: str, name: str, data: List[dict] = None, client_id: str = '') -> Dict:
    if data is None:
        data = []
    sheet_id = str(int(time.time())) + str(random.randint(100, 999))
    now = datetime.now(timezone.utc).isoformat()

    sheet_meta = {
        'id': sheet_id,
        'name': name or f"Untitled Sheet — {datetime.now().strftime('%Y-%m-%d %H:%M')}",
        'created': now,
        'modified': now,
        'itemCount': len(data),
        'user': user_id,
        'client_id': client_id,
    }

    # Write data file
    path = _sheet_path(user_id, sheet_id)
    with open(path, 'w') as f:
        json.dump(data, f, indent=2)

    # Update metadata
    meta = _load_metadata()
    meta.setdefault(user_id, []).append(sheet_meta)
    _save_metadata(meta)

    return sheet_meta


def load_sheet_data(user_id: str, sheet_id: str) -> Optional[List[dict]]:
    path = _sheet_path(user_id, sheet_id)
    if not os.path.exists(path):
        return None
    try:
        with open(path, 'r') as f:
            return json.load(f)
    except Exception:
        return None


def update_sheet(user_id: str, sheet_id: str, data: List[dict]) -> bool:
    path = _sheet_path(user_id, sheet_id)
    with open(path, 'w') as f:
        json.dump(data, f, indent=2)

    # Update metadata counts
    meta = _load_metadata()
    if user_id in meta:
        for sheet in meta[user_id]:
            if sheet['id'] == sheet_id:
                sheet['modified'] = datetime.now(timezone.utc).isoformat()
                sheet['itemCount'] = len(data)
                break
        _save_metadata(meta)
    return True


def delete_sheet(user_id: str, sheet_id: str):
    path = _sheet_path(user_id, sheet_id)
    if os.path.exists(path):
        os.remove(path)

    meta = _load_metadata()
    if user_id in meta:
        meta[user_id] = [s for s in meta[user_id] if s['id'] != sheet_id]
        _save_metadata(meta)


def rename_sheet(user_id: str, sheet_id: str, new_name: str) -> bool:
    meta = _load_metadata()
    if user_id not in meta:
        return False
    for sheet in meta[user_id]:
        if sheet['id'] == sheet_id:
            sheet['name'] = new_name
            sheet['modified'] = datetime.now(timezone.utc).isoformat()
            _save_metadata(meta)
            return True
    return False


def duplicate_sheet(user_id: str, sheet_id: str) -> Optional[Dict]:
    data = load_sheet_data(user_id, sheet_id)
    if data is None:
        return None

    meta = _load_metadata()
    original_name = "Copy of Sheet"
    for sheet in meta.get(user_id, []):
        if sheet['id'] == sheet_id:
            original_name = f"Copy of {sheet['name']}"
            break

    return create_sheet(user_id, original_name, data)


def get_sheet_client_id(user_id: str, sheet_id: str) -> Optional[str]:
    """Return the client_id associated with a sheet, or None."""
    meta = _load_metadata()
    for sheet in meta.get(user_id, []):
        if sheet['id'] == sheet_id:
            return sheet.get('client_id') or None
    return None


def set_sheet_client_id(user_id: str, sheet_id: str, client_id: str):
    """Update the client_id on an existing sheet."""
    meta = _load_metadata()
    if user_id in meta:
        for sheet in meta[user_id]:
            if sheet['id'] == sheet_id:
                sheet['client_id'] = client_id
                _save_metadata(meta)
                return True
    return False


def generate_next_id(data: List[dict]) -> str:
    """Generate the next DEL-NNN id."""
    max_id = 0
    for row in data:
        num_str = row.get('Number', '').replace('DEL-', '')
        try:
            n = int(num_str)
            if n > max_id:
                max_id = n
        except ValueError:
            pass
    return f"DEL-{str(max_id + 1).zfill(3)}"