"""DB-touching operations for the manifest store.

Kept out of the CLI and routes so both share one implementation:
- `replace_scope_draft` imports/re-imports a scope's DRAFT entries WITHOUT
  touching its published-version history (re-import is idempotent + safe).
- `publish_scope` freezes the current draft into a new immutable snapshot.
- `rollback_scope` / `export_scope_to_share` round out the publish lifecycle.
"""

import os
import tempfile
from datetime import datetime, timezone

from sqlalchemy import func

from shopdb.api import db

from .models import (
    ManifestScope, ManifestPublishedVersion, ManifestEnforcementReport,
    ManifestEnforcementResult,
)
from .importer import build_entry
from .serializer import scope_to_json


def _utcnow():
    return datetime.now(timezone.utc).replace(tzinfo=None)


def replace_scope_draft(scopename, phase, manifest):
    """Create/refresh a scope and REPLACE its draft entries. Published versions
    are left untouched. Returns the scope (uncommitted)."""
    scope = ManifestScope.query.filter_by(
        scopename=scopename, phase=phase).first()
    if not scope:
        scope = ManifestScope(scopename=scopename, phase=phase)
        db.session.add(scope)
    scope.manifestversion = str(manifest.get('Version', '1.0'))
    scope.topcomment = manifest.get('_comment')
    scope.site = manifest.get('Site')
    scope.iscommon = (scopename == 'common')

    for entry in list(scope.entries):
        db.session.delete(entry)
    db.session.flush()

    for i, entry_dict in enumerate(manifest.get('Applications') or []):
        scope.entries.append(build_entry(entry_dict, i))
    return scope


def publish_scope(scopename, phase, notes=None, publishedby=None):
    """Freeze the current draft into a new published snapshot. Returns the
    version number (uncommitted)."""
    scope = ManifestScope.query.filter_by(
        scopename=scopename, phase=phase).first()
    if not scope:
        raise ValueError(f'No scope {scopename}/{phase}')

    text = scope_to_json(scope)
    maxversion = db.session.query(
        func.max(ManifestPublishedVersion.versionnumber)
    ).filter_by(scopeid=scope.scopeid).scalar() or 0

    ManifestPublishedVersion.query.filter_by(
        scopeid=scope.scopeid, iscurrent=True
    ).update({'iscurrent': False})

    db.session.add(ManifestPublishedVersion(
        scopeid=scope.scopeid,
        versionnumber=maxversion + 1,
        manifestjson=text,
        publishedat=_utcnow(),
        publishedby=publishedby,
        iscurrent=True,
        notes=notes))
    return maxversion + 1


def rollback_scope(scopename, phase, versionnumber):
    """Make an older published version current again (uncommitted)."""
    scope = ManifestScope.query.filter_by(
        scopename=scopename, phase=phase).first()
    if not scope:
        raise ValueError(f'No scope {scopename}/{phase}')
    target = ManifestPublishedVersion.query.filter_by(
        scopeid=scope.scopeid, versionnumber=versionnumber).first()
    if not target:
        raise ValueError(f'No version {versionnumber} for {scopename}')
    ManifestPublishedVersion.query.filter_by(
        scopeid=scope.scopeid, iscurrent=True
    ).update({'iscurrent': False})
    target.iscurrent = True
    return versionnumber


def record_enforcement_report(payload):
    """Record one PC's enforcement cycle (observed state). Upserts the latest
    report per (hostname, scopename, phase) and keeps prior ones as history.

    Payload (all but hostname optional):
      hostname, scopename, phase, appliedversion, enforcerversion, lastcheckin,
      counts {installed, skipped, failed, filtered},
      results [{name, action, selfhealed, exitcode, message}]

    Returns the new ManifestEnforcementReport (uncommitted).
    """
    hostname = (payload.get('hostname') or '').strip()
    if not hostname:
        raise ValueError('hostname is required')
    scopename = (payload.get('scopename') or '').strip()
    phase = (payload.get('phase') or 'runtime').strip()
    counts = payload.get('counts') or {}
    results = payload.get('results') or []

    failed = int(counts.get('failed', 0))
    installed = int(counts.get('installed', 0))
    # Derive status from EXPLICIT self-heal flags only, never the raw installed
    # count: every healthy cycle runs Always/no-detection scripts (asset report,
    # VNC firewall, EventSaver) that the engine counts as "installed", so keying
    # self-heal off installed>0 would mark the common scope selfhealed forever
    # and make 'ok' unreachable. A drift correction is one the client flags.
    if failed > 0:
        status = 'failed'
    elif any(r.get('selfhealed') for r in results):
        status = 'selfhealed'
    else:
        status = 'ok'

    # Demote the prior current report for this host+scope. Hostname match is
    # case-insensitive to match the ilike read path - otherwise a PC reporting
    # its name in different casing would leave two iscurrent rows.
    ManifestEnforcementReport.query.filter(
        func.lower(ManifestEnforcementReport.hostname) == hostname.lower(),
        ManifestEnforcementReport.scopename == scopename,
        ManifestEnforcementReport.phase == phase,
        ManifestEnforcementReport.iscurrent == True
    ).update({'iscurrent': False}, synchronize_session=False)

    report = ManifestEnforcementReport(
        hostname=hostname,
        scopename=scopename,
        phase=phase,
        appliedversion=payload.get('appliedversion'),
        enforcerversion=payload.get('enforcerversion'),
        installedcount=installed,
        skippedcount=int(counts.get('skipped', 0)),
        failedcount=failed,
        filteredcount=int(counts.get('filtered', 0)),
        status=status,
        lastcheckin=_parse_dt(payload.get('lastcheckin')),
        receivedat=_utcnow(),
        iscurrent=True)
    for item in results:
        report.results.append(ManifestEnforcementResult(
            entryname=item.get('name', ''),
            action=item.get('action', ''),
            # Explicit flag only; do NOT infer from action == 'installed'
            # (Always/no-detection scripts install every cycle without being a
            # drift correction).
            selfhealed=bool(item.get('selfhealed', False)),
            exitcode=item.get('exitcode'),
            message=item.get('message')))
    db.session.add(report)
    return report


def _parse_dt(value):
    if not value:
        return None
    try:
        return datetime.fromisoformat(str(value).replace('Z', '+00:00')).replace(
            tzinfo=None)
    except (ValueError, TypeError):
        return None


def export_scope_to_share(scopename, phase, shareroot):
    """Write a scope's current published JSON to the share, backing up the old
    file to _meta/history first. Returns the written path."""
    scope = ManifestScope.query.filter_by(
        scopename=scopename, phase=phase).first()
    if not scope:
        raise ValueError(f'No scope {scopename}/{phase}')
    published = scope.publishedversions.filter_by(iscurrent=True).first()
    if not published:
        raise ValueError(f'{scopename} has no published version')

    if phase == 'preinstall':
        target = os.path.join(shareroot, 'preinstall.json')
    else:
        target = os.path.join(shareroot, scopename, 'manifest.json')
    os.makedirs(os.path.dirname(target), exist_ok=True)

    if os.path.isfile(target):
        historydir = os.path.join(shareroot, '_meta', 'history')
        os.makedirs(historydir, exist_ok=True)
        stamp = _utcnow().strftime('%Y%m%d-%H%M%S')
        with open(target) as src:
            old = src.read()
        with open(os.path.join(historydir, f'{stamp}-{scopename}.json'), 'w') as dst:
            dst.write(old)

    # Atomic write: a partial/failed write must never leave the live on-share
    # manifest (which every PC reads) truncated. Write a temp file in the same
    # directory, then rename over the target.
    targetdir = os.path.dirname(target)
    fd, tmppath = tempfile.mkstemp(dir=targetdir, suffix='.tmp')
    try:
        with os.fdopen(fd, 'w') as handle:
            handle.write(published.manifestjson)
        os.replace(tmppath, target)
    except Exception:
        if os.path.exists(tmppath):
            os.remove(tmppath)
        raise
    return target