from typing import ClassVar
from uuid import uuid1
from io import BytesIO
from asyncio import create_task
from json import loads, dumps
from pickle import dump, HIGHEST_PROTOCOL, loads as loads_pickle
from time import time
import logging

import pandas as pd
import geopandas as gpd
from asyncpg.exceptions import UndefinedTableError, InterfaceError
from redis import asyncio as aioredis
from pydantic import create_model

from .config import conf
# from gisaf.models.live import LiveModel
from .utils import (SHAPELY_TYPE_TO_MAPBOX_TYPE, DEFAULT_MAPBOX_LAYOUT,
    DEFAULT_MAPBOX_PAINT, gisTypeSymbolMap)
from .registry import registry
#from .models.geom import GeomGroup, GeomModel
from .models.geo_models_base import LiveGeoModel

logger = logging.getLogger(__name__)

ttag_function = """
CREATE OR REPLACE FUNCTION gisaf.ttag() RETURNS trigger LANGUAGE plpgsql AS
$$
BEGIN
PERFORM(select pg_notify('gisaf_ttag', TG_TABLE_SCHEMA || '.' || TG_TABLE_NAME));
RETURN NULL;
END;
$$
;
"""

ttag_drop_trigger = 'DROP TRIGGER IF EXISTS gisaf_ttag ON "{schema}"."{table}";'

ttag_create_trigger = """
CREATE TRIGGER gisaf_ttag AFTER INSERT OR UPDATE OR DELETE
ON "{schema}"."{table}"
FOR EACH STATEMENT
EXECUTE FUNCTION gisaf.ttag();
"""

## From https://dba.stackexchange.com/questions/121717/get-triggers-table-names-in-postgresql
get_all_triggers = """
SELECT trg.tgname as tigger_name,
    CASE trg.tgtype::INTEGER & 66
        WHEN 2 THEN 'BEFORE'
        WHEN 64 THEN 'INSTEAD OF'
        ELSE 'AFTER'
    END AS trigger_type,
    CASE trg.tgtype::INTEGER & cast(28 AS INT2)
        WHEN 16 THEN 'UPDATE'
        WHEN 8 THEN 'DELETE'
        WHEN 4 THEN 'INSERT'
        WHEN 20 THEN 'INSERT, UPDATE'
        WHEN 28 THEN 'INSERT, UPDATE, DELETE'
        WHEN 24 THEN 'UPDATE, DELETE'
        WHEN 12 THEN 'INSERT, DELETE'
    END AS trigger_event,
    ns.nspname||'.'||tbl.relname AS trigger_table,
    obj_description(trg.oid) AS remarks,
        CASE
        WHEN trg.tgenabled='O' THEN 'ENABLED'
        ELSE 'DISABLED'
    END AS status,
    CASE trg.tgtype::INTEGER & 1
        WHEN 1 THEN 'ROW'::TEXT
        ELSE 'STATEMENT'::TEXT
    END AS trigger_level,
    n.nspname || '.' || proc.proname AS function_name
FROM pg_trigger trg
    JOIN pg_proc proc ON proc.oid = trg.tgfoid
    JOIN pg_catalog.pg_namespace n ON n.oid = proc.pronamespace
    JOIN pg_class tbl ON trg.tgrelid = tbl.oid
    JOIN pg_namespace ns ON ns.oid = tbl.relnamespace
WHERE
    trg.tgname not like 'RI_ConstraintTrigger%'
    AND trg.tgname not like 'pg_sync_pg%';
"""

class RedisError(Exception):
    pass

class Store:
    """
    Store for redis:
    - redis: RedisConnection
    - pub (/sub) connections
    """
    async def setup(self):
        """
        Setup the live service for the main Gisaf application:
            - Create connection for the publishers
            - Create connection for redis listeners (websocket service)
        """
        await self.create_connections()
        await self.get_live_layer_defs()

    async def create_connections(self):
        """
        Create the connection for the publisher
        XXX: this should be renamed to be explicit
        """
        self.redis = aioredis.from_url(conf.gisaf_live.redis)
        self.pub = self.redis.pubsub()
        await self.redis.client_setname(str(uuid1()))
        self.uuid = await self.redis.client_getname()
        self.uuid = str(uuid1())


    def get_json_channel(self, store_name):
        """
        Name of the Redis channel for the json representation
        """
        return f'{store_name}:json'

    def get_gdf_channel(self, store_name):
        """
        Name of the Redis channel for the source gdf, in pickle format
        """
        return f'{store_name}:gdf'

    def get_layer_def_channel(self, store_name):
        """
        Name of the Redis channel for the layer definition
        """
        return f'{store_name}:layer_def'

    def get_mapbox_layout_channel(self, store_name):
        """
        Name of the Redis channel for the mapbox layout style definition
        """
        return f'{store_name}:mapbox_layout'

    def get_mapbox_paint_channel(self, store_name):
        """
        Name of the Redis channel for the mapbox paint style definition
        """
        return f'{store_name}:mapbox_paint'

    async def store_json(self, model, geojson, **kwargs):
        """
        Store the json representation of the gdf for caching.
        """
        ## Save in Redis channel
        channel = self.get_json_channel(model.get_store_name())
        await self.redis.set(channel, geojson)
        ## XXX: publish to websocket?
        #await self.pub.publish(self.get_json_channel(store_name), data)

    async def publish(self, *args, **kwargs):
        """
        Wrapper for publishing to the redis pubsub channel
        """
        return await self.redis.publish(*args, **kwargs)

    async def publish_gdf(self, live_name, gdf, **kwargs):
        """
        Create or update the live layer, store in redis.
        Additionally, publish to the channel for websocket live updates to ws_clients
        """
        if gdf is None:
            gdf = gpd.GeoDataFrame(data={'geom': []}, geometry='geom')
        if isinstance(gdf.index, pd.core.indexes.multi.MultiIndex):
            raise ValueError('Gisaf live does not accept dataframes with multi index')
        return await self._store_live_to_redis(live_name, gdf, **kwargs)

    async def _store_live_to_redis(self, live_name, gdf, properties=None,
            mapbox_paint=None, mapbox_layout=None, info=None,
            viewable_role=None, z_index=499, description='',
            status='L', symbol=None, color=None, attribution=None,
            **kwargs):
        """
        Store and publish the live layer data and metadata to redis channels
        """
        store_name = f'live:{live_name}'
        ## Filter empty geometries
        gdf = gdf[gdf[gdf.geometry.name].notnull()]
        ## Reproject eventually
        if 'status' not in gdf.columns:
            gdf['status'] = status
        if 'popup' not in gdf.columns:
            gdf['popup'] = 'Live: ' + live_name + ' #' + gdf.index.astype('U')
        if len(gdf) > 0:
            gdf = gdf.to_crs(conf.crs.geojson)
            gis_type = gdf.geom_type.iloc[0]
        else:
            gis_type = 'Point'  ## FIXME: cannot be inferred from the gdf?
        mapbox_type = SHAPELY_TYPE_TO_MAPBOX_TYPE.get(gis_type, None)
        if not mapbox_paint:
            mapbox_paint = DEFAULT_MAPBOX_PAINT.get(mapbox_type, {})
            if color:
                if mapbox_type == 'symbol':
                    mapbox_paint['text-color'] = color
        if not mapbox_layout:
            mapbox_layout = DEFAULT_MAPBOX_LAYOUT.get(mapbox_type, {})
            if symbol:
                mapbox_layout['text-field'] = symbol
        if not symbol:
            symbol = gisTypeSymbolMap.get(gis_type, '\ue02e')
        if properties == None:
            properties = []
        ## Add a column for json representation
        columns = {'status', 'popup', gdf.geometry.name, 'store', 'id'}
        geojson = gdf[list(columns.intersection(gdf.columns).union(properties))].to_json()
        ## Publish to websocket
        await self.redis.publish(self.get_json_channel(store_name), geojson)
        layer_def_data = dumps({
            'store': store_name,
            'z_index': z_index,
            'count': len(gdf),
            'mapbox_type': mapbox_type,
            'gis_type': gis_type,
            'symbol': symbol,
            'name': live_name,
            'description': description,
            'viewable_role': viewable_role,
            'attribution': attribution,
            'is_live': True,
        })
        ## Pickle the dataframe
        with BytesIO() as buf:
            dump(gdf, buf, protocol=HIGHEST_PROTOCOL)
            buf.seek(0)
            #df_blob = buf.read()
            await self.redis.set(self.get_gdf_channel(store_name), buf.read())

        ## Save in Redis channels
        await self.redis.set(self.get_json_channel(store_name), geojson)
        await self.redis.set(
            self.get_mapbox_layout_channel(store_name),
            dumps(mapbox_layout)
        )
        await self.redis.set(self.get_mapbox_paint_channel(store_name), dumps(mapbox_paint))
        await self.redis.set(self.get_layer_def_channel(store_name), layer_def_data)

        ## Update the layers/stores registry
        await self.get_live_layer_defs()

        return geojson

    async def get_listener(self, channel):
        return await self.pub.psubscribe(channel)

    async def remove_layer(self, store_name):
        """
        Remove the layer from Gisaf Live (channel)
        """
        await self.redis.delete(self.get_json_channel(store_name))
        await self.redis.delete(self.get_layer_def_channel(store_name))
        await self.redis.delete(self.get_gdf_channel(store_name))
        await self.redis.delete(self.get_mapbox_layout_channel(store_name))
        await self.redis.delete(self.get_mapbox_paint_channel(store_name))

        ## Update the layers/stores registry
        await self.get_live_layer_defs()

    async def has_channel(self, store_name):
        return len(await self.redis.keys(self.get_json_channel(store_name))) > 0

    async def get_live_layer_def_channels(self):
        try:
            return [k.decode() for k in await self.redis.keys('live:*:layer_def')]
        except aioredis.exceptions.ConnectionError as err:
            raise RedisError('Cannot use Redis server, please restart Gisaf')

    async def get_layer_def(self, store_name):
        return loads(await self.redis.get(self.get_layer_def_channel(store_name)))

    async def get_live_layer_defs(self): # -> list[LiveGeoModel]:
        registry.geom_live_defs = {}
        for channel in sorted(await self.get_live_layer_def_channels()):
            model_info = loads(await self.redis.get(channel))
            registry.geom_live_defs[model_info['store']] = model_info
        registry.update_live_layers()

    async def get_mapbox_style(self, store_name):
        """
        Get the http headers (mapbox style) from the store name (layer_def)
        """
        paint = await self.redis.get(self.get_mapbox_paint_channel(store_name))
        layout = await self.redis.get(self.get_mapbox_layout_channel(store_name))
        style = {}
        if paint is not None:
            style['paint'] = paint.decode()
        if layout is not None:
            style['layout'] = layout.decode()
        return style

    async def get_layer_as_json(self, store_name):
        """
        Get the json from the store name (layer_def)
        """
        return await self.redis.get(self.get_json_channel(store_name))

    async def get_gdf(self, store_name, reproject=False):
        raw_data = await self.redis.get(self.get_gdf_channel(store_name))
        if raw_data == None:
            raise RedisError(f'Cannot get {store_name}: no data')
        try:
            gdf = loads_pickle(raw_data)
        except Exception as err:
            logger.exception(err)
            raise RedisError(f'Cannot get {store_name}: pickle error from redis store: {err.__class__.__name__}, {err.args[0]}')
        if len(gdf) == 0:
            raise RedisError(f'Cannot get {store_name}: empty')
        if reproject:
            gdf.to_crs(conf.crs['for_proj'], inplace=True)
        return gdf

    async def get_feature_info(self, store_name, id):
        gdf = await self.get_gdf(store_name)
        ## FIXME: requires the gdf to have an integer index, used as feature['id'] on the map
        return gdf.loc[int(id)]

    async def set_ttag(self, store_name, now):
        """
        Set the ttag for the store as 'now'
        """
        #logger.debug(f'ttag {store_name} at {now}')
        await self.redis.set(f'ttag:{store_name}', now)

    def create_task_store_ttag(self, connection, pid, channel, store_name):
        """
        Postgres/asyncpg listener for the trigger on data change.
        A task is created because this function is not asynchronous.
        """
        create_task(self.set_ttag(store_name, time()))

    async def get_ttag(self, store_name):
        """
        Get the ttag for the given store.
        ttag is the time stamp of the last modification of the store.
        If no ttag is know, create one as now.
        """
        ttag = await self.redis.get(f'ttag:{store_name}')
        if ttag:
            return ttag.decode()
        else:
            ## No ttag: Gisaf doesn't know when was the last update,
            ## ie it was restarted and the ttags are cleared on startup.
            ## Set a ttag now, using the current epoch time in seconds in hex,
            ## double quoted and add a W/ prefix as it's basically a weak ETag
            weak_now_hex = f'W/"{hex(int(time()))[2:]}"'
            await self.set_ttag(store_name, weak_now_hex)
            return weak_now_hex

    async def delete_all_ttags(self):
        """
        Delete all ttags in redis
        """
        ## Equivalient command line: redis-cli del (redis-cli --scan --pattern 'ttag:*')
        keys = await self.redis.keys('ttag:*')
        if keys:
            await self.redis.delete(*keys)

    async def _setup_db_cache_system(self):
        """
        Setup the caching system:
        - clear all Redis store at startup
        - make sure the triggers and the "change" (insert, update, delete) event emitter
            function are setup on the database server
        - listen to the DB event emitter: setup a callback function
        """
        ## Setup the function and triggers on tables
        ## Keep the connection alive: don't use a "with" block
        ## It needs to be closed correctly: see _close_permanant_db_connection
        self._permanent_conn = await db.acquire()
        self._permanent_raw_conn = await self._permanent_conn.get_raw_connection()

        ## Create the function in the database
        await self._permanent_raw_conn.execute(ttag_function)

        ## Delete all the ttags, for safety
        ## eg. the database was changed and Gisaf wasn't running, so the redis store wasn't updated
        await store.delete_all_ttags()

        ## Create DB triggers on the tables of the models
        all_triggers = await self._permanent_raw_conn.fetch(get_all_triggers)
        stores_with_trigger = {t['trigger_table'] for t in all_triggers if t['tigger_name'] == 'gisaf_ttag'}
        missing_triger_tables = set(registry.geom).difference(stores_with_trigger)
        if len(missing_triger_tables) > 0:
            logger.info(f'Create Postgres modification triggers for {len(missing_triger_tables)} tables')
            for store_name in missing_triger_tables:
                model = registry.geom[store_name]
                try:
                    await self._permanent_raw_conn.execute(ttag_create_trigger.format(
                        schema=model.__table__.schema, table=model.__table__.name))
                except UndefinedTableError:
                    logger.warning(f'table {store_name} does not exist in the database: skip modification trigger')
        ## Setup triggers on Category and Qml, for Mapbox layer styling
        for schema, table in (('gisaf_map', 'qml'), ('gisaf_survey', 'category')):
            triggers = [t for t in all_triggers
                        if t['tigger_name'] == 'gisaf_ttag' and t['trigger_table'] == f'{schema}.{table}']
            if len(triggers) == 0:
                await self._permanent_raw_conn.execute(ttag_create_trigger.format(schema=schema, table=table))

        ## Listen: define the callback function
        await self._permanent_raw_conn.add_listener('gisaf_ttag', store.create_task_store_ttag)

    async def _close_permanant_db_connection(self):
        """
        Called at aiohttp server shutdown: remove the listener and close the connections
        """
        try:
            await self._permanent_raw_conn.remove_listener('gisaf_ttag', store.create_task_store_ttag)
        except InterfaceError as err:
            logger.warning(f'Cannot remove asyncpg listener in _close_permanant_db_connection: {err}')
        await self._permanent_raw_conn.close()
        await self._permanent_conn.release()


async def setup_redis():
    global store
    await store.setup()


async def setup_redis_cache():
    global store
    await store._setup_db_cache_system()


async def shutdown_redis():
    global store
    await store._close_permanant_db_connection()


store = Store()