#!/usr/bin/env python3
"""Periodic maintenance: data retention, nightly digest email, log rotation, DB backups."""

from __future__ import annotations

import datetime
import json
import os
import sqlite3
import time
from pathlib import Path
from typing import TYPE_CHECKING, Any, Callable

from .security_utils import validate_external_url

if TYPE_CHECKING:
    pass


def _utc_now() -> datetime.datetime:
    """Current time in UTC (timezone-aware; replaces deprecated utcnow())."""
    return datetime.datetime.now(datetime.timezone.utc)


def _iso_week_key_from_ran_at(ran_at: str) -> str:
    """Derive YYYY-Www from maint.status db_backup_ran_at ISO string for weekly dedup."""
    if not ran_at:
        return ''
    try:
        s = ran_at.strip()
        if s.endswith('Z'):
            s = s[:-1] + '+00:00'
        dt = datetime.datetime.fromisoformat(s)
        if dt.tzinfo is not None:
            dt = dt.replace(tzinfo=None)
        y, w, _ = dt.isocalendar()
        return f'{y}-W{w}'
    except (ValueError, TypeError):
        return ''


def _row_n(cur: sqlite3.Cursor) -> int:
    row = cur.fetchone()
    if row is None:
        return 0
    if isinstance(row, dict):
        return int(row['n'])
    try:
        return int(dict(row)['n'])
    except (KeyError, TypeError, ValueError):
        return int(row['n'])


def _count_log_errors_last_24h(log_path: Path) -> tuple[int | str, int | str]:
    """Count ERROR / CRITICAL log lines from the last 24 hours.

    Supports default text format (`YYYY-MM-DD HH:MM:SS - name - LEVEL - msg`) and
    JSON lines from json_logging (`_JsonFormatter` in core).
    """
    cutoff_local = datetime.datetime.now() - datetime.timedelta(hours=24)
    cutoff_utc = datetime.datetime.now(datetime.timezone.utc) - datetime.timedelta(hours=24)
    err = crit = 0
    try:
        with open(log_path, encoding='utf-8', errors='replace') as fh:
            for raw in fh:
                ln = raw.rstrip('\n')
                if not ln:
                    continue
                if ln.startswith('{'):
                    try:
                        obj = json.loads(ln)
                    except json.JSONDecodeError:
                        continue
                    level = str(obj.get('level', ''))
                    ts = obj.get('timestamp', '')
                    if not ts:
                        continue
                    ts_s = str(ts).replace('Z', '+00:00')
                    try:
                        line_dt = datetime.datetime.fromisoformat(ts_s)
                    except ValueError:
                        continue
                    if line_dt.tzinfo is None:
                        line_dt = line_dt.replace(tzinfo=datetime.timezone.utc)
                    else:
                        line_dt = line_dt.astimezone(datetime.timezone.utc)
                    if line_dt < cutoff_utc:
                        continue
                    if level == 'ERROR':
                        err += 1
                    elif level == 'CRITICAL':
                        crit += 1
                    continue

                if len(ln) < 19:
                    continue
                try:
                    line_dt = datetime.datetime.strptime(ln[:19], '%Y-%m-%d %H:%M:%S')
                except ValueError:
                    continue
                if line_dt < cutoff_local:
                    continue
                if ' - CRITICAL - ' in ln:
                    crit += 1
                elif ' - ERROR - ' in ln:
                    err += 1
        return err, crit
    except OSError:
        return 'n/a', 'n/a'


class MaintenanceRunner:
    """Runs data retention, nightly email, log rotation hot-apply, and DB backups."""

    def __init__(self, bot: Any, get_current_time: Callable[[], datetime.datetime]) -> None:
        self.bot = bot
        self.logger = bot.logger
        self._get_current_time = get_current_time
        self._last_retention_stats: dict[str, Any] = {}
        self._last_db_backup_stats: dict[str, Any] = {}
        self._last_log_rotation_applied: dict[str, str] = {}

    @property
    def last_retention_stats(self) -> dict[str, Any]:
        return self._last_retention_stats

    def get_notif(self, key: str) -> str:
        try:
            val = self.bot.db_manager.get_metadata(f'notif.{key}')
            return val if val is not None else ''
        except Exception:
            return ''

    def get_maint(self, key: str) -> str:
        try:
            val = self.bot.db_manager.get_metadata(f'maint.{key}')
            return val if val is not None else ''
        except Exception:
            return ''

    def run_data_retention(self) -> None:
        """Run data retention cleanup: packet_stream, repeater tables, stats, caches, mesh_connections."""
        import asyncio

        def get_retention_days(section: str, key: str, default: int) -> int:
            try:
                if self.bot.config.has_section(section) and self.bot.config.has_option(section, key):
                    return self.bot.config.getint(section, key)
            except Exception:
                pass
            return default

        packet_stream_days = get_retention_days('Data_Retention', 'packet_stream_retention_days', 3)
        purging_log_days = get_retention_days('Data_Retention', 'purging_log_retention_days', 90)
        daily_stats_days = get_retention_days('Data_Retention', 'daily_stats_retention_days', 90)
        observed_paths_days = get_retention_days('Data_Retention', 'observed_paths_retention_days', 90)
        mesh_connections_days = get_retention_days('Data_Retention', 'mesh_connections_retention_days', 7)
        neighbor_observations_days = get_retention_days(
            'Data_Retention', 'neighbor_observations_retention_days', 365
        )
        stats_days = get_retention_days('Stats_Command', 'data_retention_days', 7)

        try:
            if hasattr(self.bot, 'web_viewer_integration') and self.bot.web_viewer_integration:
                bi = getattr(self.bot.web_viewer_integration, 'bot_integration', None)
                if bi and hasattr(bi, 'cleanup_old_data'):
                    bi.cleanup_old_data(packet_stream_days)

            if hasattr(self.bot, 'repeater_manager') and self.bot.repeater_manager:
                if hasattr(self.bot, 'main_event_loop') and self.bot.main_event_loop and self.bot.main_event_loop.is_running():
                    future = asyncio.run_coroutine_threadsafe(
                        self.bot.repeater_manager.cleanup_database(purging_log_days),
                        self.bot.main_event_loop
                    )
                    try:
                        future.result(timeout=60)
                    except Exception as e:
                        self.logger.error(f"Error in repeater_manager.cleanup_database: {e}")
                else:
                    try:
                        loop = asyncio.get_event_loop()
                    except RuntimeError:
                        loop = asyncio.new_event_loop()
                        asyncio.set_event_loop(loop)
                    loop.run_until_complete(self.bot.repeater_manager.cleanup_database(purging_log_days))
                if hasattr(self.bot.repeater_manager, 'cleanup_repeater_retention'):
                    self.bot.repeater_manager.cleanup_repeater_retention(
                        daily_stats_days=daily_stats_days,
                        observed_paths_days=observed_paths_days
                    )

            if hasattr(self.bot, 'command_manager') and self.bot.command_manager:
                stats_cmd = self.bot.command_manager.commands.get('stats') if getattr(self.bot.command_manager, 'commands', None) else None
                if stats_cmd and hasattr(stats_cmd, 'cleanup_old_stats'):
                    stats_cmd.cleanup_old_stats(stats_days)

            if hasattr(self.bot, 'db_manager') and self.bot.db_manager and hasattr(self.bot.db_manager, 'cleanup_expired_cache'):
                self.bot.db_manager.cleanup_expired_cache()

            if hasattr(self.bot, 'mesh_graph') and self.bot.mesh_graph and hasattr(self.bot.mesh_graph, 'delete_expired_edges_from_db'):
                self.bot.mesh_graph.delete_expired_edges_from_db(mesh_connections_days)

            # neighbor_observations is per-cycle history; neighbor_links is the
            # aggregate adjacency the mesh graph reads and is deliberately not
            # pruned here (losing it would silently drop confirmed direct links).
            self._cleanup_neighbor_observations(neighbor_observations_days)

            ran_at = _utc_now().isoformat()
            self._last_retention_stats['ran_at'] = ran_at
            try:
                self.bot.db_manager.set_metadata('maint.status.data_retention_ran_at', ran_at)
                self.bot.db_manager.set_metadata('maint.status.data_retention_outcome', 'ok')
            except Exception:
                pass

        except Exception as e:
            self.logger.exception(f"Error during data retention cleanup: {e}")
            self._last_retention_stats['error'] = str(e)
            try:
                ran_at = _utc_now().isoformat()
                self.bot.db_manager.set_metadata('maint.status.data_retention_ran_at', ran_at)
                self.bot.db_manager.set_metadata('maint.status.data_retention_outcome', f'error: {e}')
            except Exception:
                pass

    def _cleanup_neighbor_observations(self, retention_days: int) -> None:
        """Prune zero-hop neighbor observation history past the retention window.

        Volume is tiny (at most one row per neighbor per cycle, and cycles are
        12h apart at minimum), so the default window is generous — the point of
        this table is the long-run signal history.
        """
        if retention_days <= 0:
            return
        db_manager = getattr(self.bot, 'db_manager', None)
        if not db_manager or not hasattr(db_manager, 'delete_timestamp_rows_in_chunks'):
            return
        try:
            cutoff = (_utc_now() - datetime.timedelta(days=retention_days)).isoformat()
            deleted = db_manager.delete_timestamp_rows_in_chunks(
                'neighbor_observations',
                'observed_at',
                cutoff,
                progress_label='neighbor observations',
            )
            if deleted > 0:
                self.logger.info(
                    f"Cleaned up {deleted} old neighbor_observations entries "
                    f"(older than {retention_days} days)"
                )
        except Exception as e:
            # A missing table (pre-migration-22 database) must not abort the rest
            # of the retention run.
            self.logger.debug(f"Neighbor observation retention skipped: {e}")

    def collect_email_stats(self) -> dict[str, Any]:
        """Gather summary stats for the nightly digest."""
        stats: dict[str, Any] = {}

        try:
            start = getattr(self.bot, 'connection_time', None)
            if start:
                delta = datetime.timedelta(seconds=int(time.time() - start))
                hours, rem = divmod(delta.seconds, 3600)
                minutes = rem // 60
                parts = []
                if delta.days:
                    parts.append(f"{delta.days}d")
                parts.append(f"{hours}h {minutes}m")
                stats['uptime'] = ' '.join(parts)
            else:
                stats['uptime'] = 'unknown'
        except Exception:
            stats['uptime'] = 'unknown'

        try:
            with self.bot.db_manager.connection() as conn:
                cur = conn.cursor()
                cur.execute("SELECT COUNT(*) AS n FROM complete_contact_tracking")
                stats['contacts_total'] = _row_n(cur)
                cur.execute(
                    "SELECT COUNT(*) AS n FROM complete_contact_tracking "
                    "WHERE last_heard >= datetime('now', '-1 day')"
                )
                stats['contacts_24h'] = _row_n(cur)
                cur.execute(
                    "SELECT COUNT(*) AS n FROM complete_contact_tracking "
                    "WHERE first_heard >= datetime('now', '-1 day')"
                )
                stats['contacts_new_24h'] = _row_n(cur)
        except Exception as e:
            stats['contacts_error'] = str(e)

        try:
            db_path = str(self.bot.db_manager.db_path)
            size_bytes = os.path.getsize(db_path)
            stats['db_size_mb'] = f'{size_bytes / 1_048_576:.1f}'
            stats['db_path'] = db_path
        except Exception:
            stats['db_size_mb'] = 'unknown'

        try:
            log_file = self.bot.config.get('Logging', 'log_file', fallback='').strip()
            if log_file:
                log_path = Path(log_file)
                stats['log_file'] = str(log_path)
                if log_path.exists():
                    stats['log_size_mb'] = f'{log_path.stat().st_size / 1_048_576:.1f}'
                    err_ct, crit_ct = _count_log_errors_last_24h(log_path)
                    stats['errors_24h'] = err_ct
                    stats['criticals_24h'] = crit_ct
                    backup = Path(str(log_path) + '.1')
                    if backup.exists() and (time.time() - backup.stat().st_mtime) < 86400:
                        stats['log_rotated_24h'] = True
                        stats['log_backup_size_mb'] = f'{backup.stat().st_size / 1_048_576:.1f}'
                    else:
                        stats['log_rotated_24h'] = False
        except Exception:
            pass

        stats['retention'] = self._last_retention_stats.copy()
        return stats

    def format_email_body(self, stats: dict[str, Any], period_start: str, period_end: str) -> str:
        lines = [
            'MeshCore Bot — Nightly Maintenance Report',
            '=' * 44,
            f'Period : {period_start} → {period_end}',
            '',
            'BOT STATUS',
            '─' * 30,
            f"  Uptime    : {stats.get('uptime', 'unknown')}",
            f"  Connected : {'yes' if getattr(self.bot, 'connected', False) else 'no'}",
            '',
            'NETWORK ACTIVITY (past 24 h)',
            '─' * 30,
            f"  Active contacts  : {stats.get('contacts_24h', 'n/a')}",
            f"  New contacts     : {stats.get('contacts_new_24h', 'n/a')}",
            f"  Total tracked    : {stats.get('contacts_total', 'n/a')}",
            '',
            'DATABASE',
            '─' * 30,
            f"  Size : {stats.get('db_size_mb', 'n/a')} MB",
        ]
        if self._last_retention_stats.get('ran_at'):
            lines.append(f"  Last retention run : {self._last_retention_stats['ran_at']} UTC")
        if self._last_retention_stats.get('error'):
            lines.append(f"  Retention error    : {self._last_retention_stats['error']}")

        lines += [
            '',
            'ERRORS (past 24 h, log file)',
            '─' * 30,
            f"  ERROR    : {stats.get('errors_24h', 'n/a')}",
            f"  CRITICAL : {stats.get('criticals_24h', 'n/a')}",
        ]
        if stats.get('log_file'):
            lines += [
                '',
                'LOG FILES',
                '─' * 30,
                f"  Current : {stats.get('log_file')} ({stats.get('log_size_mb', '?')} MB)",
            ]
            if stats.get('log_rotated_24h'):
                lines.append(
                    f"  Rotated : yes — backup is {stats.get('log_backup_size_mb', '?')} MB"
                )
            else:
                lines.append('  Rotated : no')

        lines += [
            '',
            '─' * 44,
            'Manage notification settings: /config',
        ]
        return '\n'.join(lines)

    def send_nightly_email(self) -> None:
        """Build and dispatch the nightly maintenance digest if enabled."""
        import smtplib
        import ssl as _ssl
        from email.message import EmailMessage

        if self.get_notif('nightly_enabled') != 'true':
            return

        smtp_host = self.get_notif('smtp_host')
        smtp_security = self.get_notif('smtp_security') or 'starttls'
        smtp_user = self.get_notif('smtp_user')
        smtp_password = self.get_notif('smtp_password')
        from_name = self.get_notif('from_name') or 'MeshCore Bot'
        from_email = self.get_notif('from_email')
        recipients = [r.strip() for r in self.get_notif('recipients').split(',') if r.strip()]

        if not smtp_host or not from_email or not recipients:
            self.logger.warning(
                "Nightly email enabled but SMTP settings incomplete "
                f"(host={smtp_host!r}, from={from_email!r}, recipients={recipients})"
            )
            return

        allow_local = self.get_notif('allow_local_smtp').lower() == 'true'
        if not validate_external_url(f'http://{smtp_host}', allow_private=allow_local):
            self.logger.error(
                "Nightly email aborted: SMTP host %r resolves to a private or reserved address",
                smtp_host,
            )
            return

        try:
            smtp_port = int(self.get_notif('smtp_port') or (465 if smtp_security == 'ssl' else 587))
        except ValueError:
            smtp_port = 587

        now_utc = _utc_now()
        yesterday = now_utc - datetime.timedelta(days=1)
        period_start = yesterday.strftime('%Y-%m-%d %H:%M UTC')
        period_end = now_utc.strftime('%Y-%m-%d %H:%M UTC')

        try:
            stats = self.collect_email_stats()
            body = self.format_email_body(stats, period_start, period_end)

            msg = EmailMessage()
            msg['Subject'] = f'MeshCore Bot — Nightly Report {now_utc.strftime("%Y-%m-%d")}'
            msg['From'] = f'{from_name} <{from_email}>'
            msg['To'] = ', '.join(recipients)
            msg.set_content(body)

            if self.get_maint('email_attach_log') == 'true':
                log_file = self.bot.config.get('Logging', 'log_file', fallback='').strip()
                if log_file:
                    log_path = Path(log_file)
                    max_attach = 5 * 1024 * 1024
                    if log_path.exists() and log_path.stat().st_size <= max_attach:
                        try:
                            with open(log_path, 'rb') as fh:
                                msg.add_attachment(fh.read(), maintype='text', subtype='plain',
                                                   filename=log_path.name)
                        except Exception as attach_err:
                            self.logger.warning(f"Could not attach log file to nightly email: {attach_err}")

            context = _ssl.create_default_context()
            _smtp_timeout = 30
            if smtp_security == 'ssl':
                with smtplib.SMTP_SSL(smtp_host, smtp_port, context=context, timeout=_smtp_timeout) as s:
                    if smtp_user and smtp_password:
                        s.login(smtp_user, smtp_password)
                    s.send_message(msg)
            else:
                with smtplib.SMTP(smtp_host, smtp_port, timeout=_smtp_timeout) as s:
                    if smtp_security == 'starttls':
                        s.ehlo()
                        s.starttls(context=context)
                        s.ehlo()
                    if smtp_user and smtp_password:
                        s.login(smtp_user, smtp_password)
                    s.send_message(msg)

            self.logger.info(
                f"Nightly maintenance email sent to {recipients} "
                f"(contacts_24h={stats.get('contacts_24h')}, "
                f"errors={stats.get('errors_24h')})"
            )
            try:
                ran_at = _utc_now().isoformat()
                self.bot.db_manager.set_metadata('maint.status.nightly_email_ran_at', ran_at)
                self.bot.db_manager.set_metadata('maint.status.nightly_email_outcome', 'ok')
            except Exception:
                pass

        except Exception as e:
            self.logger.error(f"Failed to send nightly maintenance email: {e}")
            try:
                ran_at = _utc_now().isoformat()
                self.bot.db_manager.set_metadata('maint.status.nightly_email_ran_at', ran_at)
                self.bot.db_manager.set_metadata('maint.status.nightly_email_outcome', f'error: {e}')
            except Exception:
                pass

    def apply_log_rotation_config(self) -> None:
        """Check bot_metadata for log rotation settings and replace the RotatingFileHandler if changed."""
        from logging.handlers import RotatingFileHandler as _RFH

        max_bytes_str = self.get_maint('log_max_bytes')
        backup_count_str = self.get_maint('log_backup_count')

        if not max_bytes_str and not backup_count_str:
            return

        new_cfg = {'max_bytes': max_bytes_str, 'backup_count': backup_count_str}
        if new_cfg == self._last_log_rotation_applied:
            return

        try:
            max_bytes = int(max_bytes_str) if max_bytes_str else 5 * 1024 * 1024
            backup_count = int(backup_count_str) if backup_count_str else 3
        except ValueError:
            self.logger.warning(f"Invalid log rotation config in bot_metadata: {new_cfg}")
            return

        logger = self.bot.logger
        for i, handler in enumerate(logger.handlers):
            if isinstance(handler, _RFH):
                log_path = handler.baseFilename
                formatter = handler.formatter
                level = handler.level
                handler.close()
                new_handler = _RFH(log_path, maxBytes=max_bytes, backupCount=backup_count, encoding='utf-8')
                new_handler.setFormatter(formatter)
                new_handler.setLevel(level)
                logger.handlers[i] = new_handler
                self._last_log_rotation_applied = new_cfg
                self.logger.info(f"Log rotation config applied: maxBytes={max_bytes}, backupCount={backup_count}")
                try:
                    ran_at = _utc_now().isoformat()
                    self.bot.db_manager.set_metadata('maint.status.log_rotation_applied_at', ran_at)
                except Exception:
                    pass
                break

    def maybe_run_db_backup(self) -> None:
        """Check if a scheduled DB backup is due and run it."""
        if self.get_maint('db_backup_enabled') != 'true':
            return

        sched = self.get_maint('db_backup_schedule') or 'daily'
        if sched == 'manual':
            return

        backup_time_str = self.get_maint('db_backup_time') or '02:00'
        now = self._get_current_time()
        try:
            bh, bm = [int(x) for x in backup_time_str.split(':')]
        except Exception:
            bh, bm = 2, 0

        scheduled_today = now.replace(hour=bh, minute=bm, second=0, microsecond=0)
        fire_window_end = scheduled_today + datetime.timedelta(minutes=2)
        if now < scheduled_today or now > fire_window_end:
            return

        if sched == 'weekly' and now.weekday() != 0:
            return

        if not self._last_db_backup_stats:
            try:
                db_ran_at = self.bot.db_manager.get_metadata('maint.status.db_backup_ran_at') or ''
                if db_ran_at:
                    self._last_db_backup_stats['ran_at'] = db_ran_at
                    wk = _iso_week_key_from_ran_at(db_ran_at)
                    if wk:
                        self._last_db_backup_stats['week_key'] = wk
            except Exception:
                pass

        date_key = now.strftime('%Y-%m-%d')
        week_key = f"{now.year}-W{now.isocalendar()[1]}"
        last_ran = self._last_db_backup_stats.get('ran_at', '')
        if sched == 'daily' and last_ran.startswith(date_key):
            return
        if sched == 'weekly':
            seeded_week = self._last_db_backup_stats.get('week_key', '')
            if seeded_week == week_key:
                return

        self.run_db_backup()
        if sched == 'weekly':
            self._last_db_backup_stats['week_key'] = week_key

    def run_db_backup(self) -> None:
        """Backup the SQLite database using sqlite3.Connection.backup(), then prune old backups."""
        import sqlite3 as _sqlite3

        backup_dir_str = self.get_maint('db_backup_dir') or '/data/backups'
        try:
            retention_count = int(self.get_maint('db_backup_retention_count') or '7')
        except ValueError:
            retention_count = 7

        backup_dir = Path(backup_dir_str)
        ran_at = _utc_now().isoformat()

        try:
            backup_dir.mkdir(parents=True, exist_ok=True)
        except OSError as e:
            self.logger.error(f"DB backup: cannot create backup directory {backup_dir}: {e}")
            wk = _iso_week_key_from_ran_at(ran_at)
            self._last_db_backup_stats = {'ran_at': ran_at, 'error': str(e), **({'week_key': wk} if wk else {})}
            try:
                self.bot.db_manager.set_metadata('maint.status.db_backup_ran_at', ran_at)
                self.bot.db_manager.set_metadata('maint.status.db_backup_outcome', f'error: {e}')
            except Exception:
                pass
            return

        db_path = Path(str(self.bot.db_manager.db_path))
        ts = _utc_now().strftime('%Y%m%dT%H%M%S')
        backup_path = backup_dir / f"{db_path.stem}_{ts}.db"

        try:
            src = _sqlite3.connect(str(db_path), check_same_thread=False)
            dst = _sqlite3.connect(str(backup_path))
            try:
                src.backup(dst, pages=200)
            finally:
                dst.close()
                src.close()

            size_mb = backup_path.stat().st_size / 1_048_576
            self.logger.info(f"DB backup created: {backup_path} ({size_mb:.1f} MB)")

            stem = db_path.stem
            backups = sorted(backup_dir.glob(f"{stem}_*.db"), key=lambda p: p.stat().st_mtime)
            while len(backups) > retention_count:
                oldest = backups.pop(0)
                try:
                    oldest.unlink()
                    self.logger.info(f"DB backup pruned: {oldest}")
                except OSError:
                    pass

            ran_at = _utc_now().isoformat()
            wk = _iso_week_key_from_ran_at(ran_at)
            self._last_db_backup_stats = {
                'ran_at': ran_at,
                'path': str(backup_path),
                'size_mb': f'{size_mb:.1f}',
                **({'week_key': wk} if wk else {}),
            }
            try:
                self.bot.db_manager.set_metadata('maint.status.db_backup_ran_at', ran_at)
                self.bot.db_manager.set_metadata('maint.status.db_backup_outcome', 'ok')
                self.bot.db_manager.set_metadata('maint.status.db_backup_path', str(backup_path))
            except Exception:
                pass

        except Exception as e:
            self.logger.error(f"DB backup failed: {e}")
            wk = _iso_week_key_from_ran_at(ran_at)
            self._last_db_backup_stats = {'ran_at': ran_at, 'error': str(e), **({'week_key': wk} if wk else {})}
            try:
                self.bot.db_manager.set_metadata('maint.status.db_backup_ran_at', ran_at)
                self.bot.db_manager.set_metadata('maint.status.db_backup_outcome', f'error: {e}')
            except Exception:
                pass