"""Backup kind registry.

A "kind" is one category of configuration backup (NTLARS/DNC registry, part
marker, UDC, CMM ...). Each kind declares three things the rest of the plugin
needs and nothing else:

  where its bytes live      'shopdb' (parsed into payloadjson) or 'share'
                            (opaque vendor file left on the SFLD share)
  how to resolve an asset   the collector reports an identifier; the kind turns
                            it into the assetid the revision belongs to
  how to render downloads   one or more output formats

Adding a kind is a class plus one REGISTRY entry. Nothing else in the plugin
knows kind names.
"""

import hashlib
import json

from . import ntlars as ntlarscodec

# Default root of the opaque-backup tree on the SFLD share. Connected PCs write
# here directly (they need SFLD creds - a SYSTEM process hitting a UNC path
# without them gets an access-denied that Test-Path reports as "not found").
#
# This is the WEST JEFFERSON path and is only a DEFAULT: the live value is the
# backups_shareroot setting, because a bundled plugin in a multi-site product
# must not hardcode one site's file server.
DEFAULTSHAREROOT = r'\\tsgwp00525.wjs.geaerospace.net\shared\dt\shopfloor\backups'


def canonicalhash(projection):
    """sha256 over the SEMANTIC content only. Dedup key for 'shopdb' kinds.

    Deliberately hashes just schema + keys, excluding sourcedialect. The same
    settings exported through NTLARS's Save... button and through a scripted
    reg export parse to identical keys but differing sourcedialect; hashing the
    whole projection would record that as a change and produce a spurious
    revision every time the collection route changed. Storage is
    dialect-neutral, so the dedup key has to be too.
    """
    subset = {
        'schema': projection.get('schema'),
        'keys': projection.get('keys'),
    }
    blob = json.dumps(subset, sort_keys=True, separators=(',', ':'))
    return hashlib.sha256(blob.encode('utf-8')).hexdigest()


def byteshash(raw):
    """sha256 over raw bytes. Dedup key for 'share' kinds."""
    return hashlib.sha256(raw).hexdigest()


class BackupKind:
    """Base class. Subclasses override what applies to them."""

    key = None
    displayname = None
    storagebackend = 'shopdb'
    assettypes = ['*']
    # Text shown when the kind has no revisions for an asset. None means the
    # panel HIDES entirely instead (the generic list renderer shows a panel
    # only when it has rows or declares empty text). Default to hiding: a kind
    # applies to an asset TYPE, but whether a given asset ever has this kind of
    # backup is a property of the individual machine. A part marker panel on
    # every one of 144 machines is noise, not information.
    emptytext = None

    def parse(self, raw):
        """Opaque kinds return None; parseable kinds return the projection."""
        return None

    def formats(self):
        """Downloadable formats: [{'id','label','ext','mimetype'}]."""
        return []

    def render(self, projection, formatid, comments=None):
        """Return (bytes, extension, mimetype) for a 'shopdb' kind."""
        raise NotImplementedError

    def resolveassetid(self, payload):
        """Map a collector payload to the assetid the backup belongs to."""
        raise NotImplementedError

    def infopanel(self):
        """Optional 'at a glance' card built from this kind's LATEST revision.

        Returns an ADR-010 panel dict, or None when the kind has no summary
        worth surfacing. Declared by the kind rather than hardcoded in the
        plugin so a successor technology (NTLARS/DNC is expected to give way to
        Shopfloor Connect) ships its own card by adding a class, without
        touching the plugin or the panel wiring.
        """
        return None

    def buildinfo(self, projection, assetid, **options):
        """Build this kind's info-card payload. Only called when infopanel()."""
        return {'fields': [], 'sectioncount': 0}

    def sharedir(self, machinetype, identifier, shareroot=None):
        """UNC directory a 'share' kind's files are expected under.

        Advisory only - the authoritative path is the sharepath the collector
        reports, since the PC is what actually wrote the file. This builds the
        conventional location for display and for validating a reported path.
        """
        return '{}\\{}\\{}\\{}'.format(
            shareroot or DEFAULTSHAREROOT,
            machinetype or 'unknown', identifier or 'unknown', self.key)


class NtlarsKind(BackupKind):
    """NTLARS / DNC registry settings.

    Collected from the CONTROLLING PC's registry but belongs to the MACHINE:
    the settings describe how to talk to that machine's controller, so they
    follow the machine when a PC is swapped. resolveassetid therefore keys on
    the reported machine number, not the hostname.
    """

    key = 'ntlars'
    displayname = 'NTLARS / DNC Settings'
    storagebackend = 'shopdb'
    assettypes = ['machine']

    @staticmethod
    def embeddedmachineno(projection):
        """The MachineNo NTLARS itself is configured with (General tab)."""
        for key in (projection or {}).get('keys', []):
            if (key.get('path') or '').lower() == 'general':
                entry = (key.get('values') or {}).get('MachineNo') or {}
                return str(entry.get('data') or '').strip()
        return ''

    def parse(self, raw):
        """Parse, then refuse to record an unconfigured NTLARS install.

        A freshly imaged PC opens NTLARS with a blank General tab (no MachineNo,
        CNC, Host or Interface type) until a tech restores the config. Storing
        that would make an empty config the newest revision at exactly the
        moment someone needs the last good one - so a blank MachineNo is
        rejected as "nothing worth backing up" rather than accepted as a change.
        Two of the 320 known-good backups on the share already have this shape.
        """
        projection = ntlarscodec.parse(raw)
        if not self.embeddedmachineno(projection):
            raise ValueError(
                'NTLARS General\\MachineNo is empty - unconfigured install, '
                'refusing to record it as a revision')
        return projection

    def formats(self):
        return [
            {
                'id': 'ntlars',
                'label': 'NTLARS Load... (.reg)',
                'ext': '.reg',
                'mimetype': 'application/octet-stream',
                'hint': 'Restore with the Load... button in the NTLARS settings dialog.',
            },
            {
                'id': 'wow6432node',
                'label': 'Direct reg import (.reg, WOW6432Node)',
                'ext': '.reg',
                'mimetype': 'application/octet-stream',
                'hint': 'Use when importing outside NTLARS on a 64-bit machine.',
            },
        ]

    def render(self, projection, formatid, comments=None):
        if formatid not in ('ntlars', 'wow6432node'):
            raise ValueError('unknown format for ntlars kind: {}'.format(formatid))
        raw = ntlarscodec.render(projection, dialect=formatid, comments=comments)
        return raw, '.reg', 'application/octet-stream'

    def infopanel(self):
        return {
            'id': 'backups-dncinfo',
            'title': 'DNC Info',
            'assettypes': ['machine'],
            'endpoint': '/api/backups/asset/{assetid}/info?kind=ntlars',
            # tabs, not keyvalue: General / eFocas / Serial / NTSHR / MARK are
            # one card the tech switches between, rather than a 30-row wall.
            # No 'empty' key - the renderer hides a panel with no sections, so
            # a machine with no NTLARS revision has no DNC Info card at all.
            'render': 'tabs',
            # Above the history panels: this answers the question a tech
            # arrives with, while history is for the rarer restore case.
            'position': 38,
        }

    def buildinfo(self, projection, assetid, **options):
        from . import dncinfo
        return dncinfo.build(projection, assetid,
                             partmarkertypes=options.get('partmarkertypes'))

    def resolveassetid(self, payload):
        from shopdb.api import db, Asset

        machinenumber = (payload.get('machinenumber') or '').strip()
        if not machinenumber:
            return None, 'no machinenumber in payload'
        asset = db.session.query(Asset).filter(
            Asset.assetnumber == machinenumber).first()
        if asset is None:
            return None, 'no asset with assetnumber {!r}'.format(machinenumber)
        return asset.assetid, None


class PartMarkerKind(BackupKind):
    """Telesis part marker configuration.

    Opaque vendor filetype with no useful JSON representation, so ShopDB stores
    metadata and a UNC pointer while the file itself stays on the share. The
    original filename and extension are preserved because the vendor tool
    rejects a renamed file.
    """

    key = 'partmarker'
    displayname = 'Part Marker Configuration'
    storagebackend = 'share'
    # NO asset panel. The marker's DNC settings are a tab on the single DNC Info
    # card, and a separate card that is empty on 145 of 147 machines earns
    # nobody anything. The kind is still fully live - it stores, dedupes and
    # serves revisions, which are listed on the backup history page.
    assettypes = []

    def resolveassetid(self, payload):
        from shopdb.api import db, Asset

        identifier = (payload.get('machinenumber')
                      or payload.get('assetnumber') or '').strip()
        if not identifier:
            return None, 'no machinenumber/assetnumber in payload'
        asset = db.session.query(Asset).filter(
            Asset.assetnumber == identifier).first()
        if asset is None:
            return None, 'no asset with assetnumber {!r}'.format(identifier)
        return asset.assetid, None


REGISTRY = {k.key: k for k in (NtlarsKind(), PartMarkerKind())}


def getkind(key):
    return REGISTRY.get((key or '').strip().lower())