"""
Code to bind the adql library to the data center software.
"""

#c Copyright 2008-2020, the GAVO project
#c
#c This program is free software, covered by the GNU GPL.  See the
#c COPYING file in the source distribution.


import sys


from gavo import adql
from gavo import base
from gavo import rsc
from gavo import rscdef
from gavo import svcs
from gavo import utils


def makeFieldInfo(column, sqlName=None):
	"""returns an adql.tree.FieldInfo object from a rscdef.Column.
	"""
	return adql.FieldInfo(column.type,
		column.unit, column.ucd, (column,), stc=column.stc, sqlName=sqlName)


class TDContext(object):
	"""An object keeping track of the generation of a table definition
	for ADQL output.
	"""
	def __init__(self):
		self.existingNames = set()
	
	def getName(self, desiredName):
		while desiredName in self.existingNames:
			desiredName = desiredName+"_"
		self.existingNames.add(desiredName)
		return desiredName


# For columns of types that have no automatic VOTable null value,
# we make up some when we don't have any yet.  This is governed by
# the following dictionary.
# All this is in particular for columns that came into being from
# expressions.
#
# This largely follows what Mark Taylor does in topcat.
_artificialNULLs = {
	"bytea": "255",
	"smallint": "-32768",
	"integer": "-2147483648",
	"bigint": "-9223372036854775808",
}

def _makeColumnFromFieldInfo(ctx, colName, fi):
	"""constructs a rscdef.Column from a field info pair as left by the
	ADQL machinery.

	The strategy:  If there's only one userData, we copy the Column
	contained in there, update the unit and the ucd, plus a warning
	if the Column has been tainted.

	If there's more or less than one userData, we create a new
	Column, use the data provided by fi and make up a description
	consisting of the source descriptions.	Add a taint warning
	if necessary.

	Since we cannot assign sensible verbLevels and assume the user wants
	to see what s/he selected, all fields get verbLevel 1.

	Types are a serious problem, handled by typesystems.
	"""
	if len(fi.userData)==1:
		res = svcs.OutputField.fromColumn(fi.userData[0])
		if hasattr(fi.userData[0], "originalName"):
			# the following is to undo column renaming for postgres-forbidden
			# column names
			colName = fi.userData[0].originalName
		elif fi.userData[0].name.lower()==colName:
			# undo case normalisation done by the ADQL machinery
			# if we're reasonably sure there's no intervening AS
			colName = fi.userData[0].name
	else: 
		res = base.makeStruct(svcs.OutputField, name=colName)

	res.name = ctx.getName(colName)
	res.ucd = fi.ucd
	res.unit = fi.unit
	res.type = fi.type

	# XXX TODO: do something with stc's "broken" attribute
	res.stc = fi.stc

	if len(fi.userData)>1:
		res.description = ("This field has traces of: %s"%("; ".join([
			f.description for f in fi.userData if f.description])))

	if fi.tainted:
		res.description = (res.description+" -- *TAINTED*: the value"
			" was operated on in a way that unit and ucd may be severely wrong")

	# The xtype may be set by the node classes; this is used downstream
	# to transform to STC-S strings.
	if "xtype" in fi.properties:
		res.xtype = fi.properties["xtype"]
		res.needMunging = True
	
	# dates and timestamps should be ISO format for TAP or consistency with it
	if res.type=="date" or res.type=="timestamp":
		res.xtype = "timestamp"
	
	# integral types must have a null value set since we can't be
	# sure that a query yields defined results for all of them.
	# Tough luck if our artificial value is already taken by the table
	# (remedy: select a suitable null value in the column metadata)
	if (res.type in _artificialNULLs 
			and (
				not (res.values and res.values.nullLiteral)
				or fi.tainted)):
		nullLiteral = _artificialNULLs[res.type]
		if res.values:
			res.feedObject("values", res.values.change(nullLiteral=nullLiteral))
		else:
			res.feedObject("values", base.makeStruct(rscdef.Values, 
				nullLiteral=nullLiteral))

	res.verbLevel = 1
	res.finishElement()
	return res


def _getTableDescForOutput(parsedTree):
	"""returns a sequence of Column instances describing the output of the
	parsed and annotated ADQL query parsedTree.
	"""
	ctx = TDContext()
	columns = [_makeColumnFromFieldInfo(ctx, *fi) 
		for fi in parsedTree.fieldInfos.seq]

	# if this is a simple one-table query, take the metadata and params
	# from that table.
	fromNames = [t.qName
		for t in parsedTree.fromClause.getAllTables()
		if hasattr(t, "qName")]

	if len(fromNames)==1:
		try:
			srcTable = base.caches.getMTH(None).getTableDefForTable(fromNames[0])
			# swallow groups for now -- we don't really use them for db tables
			# but if there are some, they'll be trouble when columns are missing.
			resTable = srcTable.change(columns=columns, groups=[], primary=())
			resTable.copyMetaFrom(srcTable)
			resTable.id = srcTable.id
			return resTable
		except base.NotFoundError:
			# Single source is not one of our tables, hence no metadata, and
			# fall through to normal table generation
			pass

	resTable = base.makeStruct(rscdef.TableDef, columns=columns,
		id=parsedTree.suggestAName())

	return resTable


def _getADQLName(col):
	"""returns the name a column is known as within the ADQL query.

	This can be different from the actual column name for uploaded
	tables, where we have to rename columns called oid, tableoid,...

	On the SQL side, our internal name is being used.
	"""
	return getattr(col, "originalName", col.name)


def adqlTableRefToDaCHS(tableName):
	"""returns a DaCHS-internal table name suitable for dc.tablemeta for
	an ADQL TableName node.

	In particular, in DaCHS we don't support catalog, so that errors
	out immediately.  Also, we don't support delimited table identifiers.
	Anything delimited not consisting exclusively of lower case letters
	must therefore fail immediately.  When they're all lowercase, people
	engaged in gratuitous quoting.  Then, just unquote and move on.
	"""
	if isinstance(tableName, str):
		return tableName

	surfaceForm = adql.flatten(tableName)
	if tableName.cat:
		raise base.NotFoundError(surfaceForm, "table", "published tables",
			hint="DaCHS services have no tables with catalog parts.")

	if isinstance(tableName.schema, utils.QuotedName):
		if not tableName.schema.isRegularLower():
			raise base.NotFoundError(surfaceForm, "table", "published tables",
				hint="You probably should not quote the table schema")
		schema = tableName.schema.name+"."
	else:
		if tableName.schema:
			schema = tableName.schema+"."
		else:
			schema = ""

	if isinstance(tableName.name, utils.QuotedName):
		if not tableName.name.isRegularLower():
			raise base.NotFoundError(surfaceForm, "table", "published tables",
				hint="You probably should not quote the table name")
		else:
			name = tableName.name.name
	else:
		name = tableName.name

	return schema+name


class DaCHSFieldInfoGetter(adql.FieldInfoGetter):
	def __init__(self, accessProfile=None, tdsForUploads=[]):
		adql.FieldInfoGetter.__init__(self)
		self.mth = base.caches.getMTH(None)
		for td in tdsForUploads:
			self.addExtraFieldInfos(
				td.id, 
				[(_getADQLName(f), makeFieldInfo(f, sqlName=f.name)) for f in td])

	def getInfosFor(self, tableName):
		td = self.mth.getTableDefForTable(
			adqlTableRefToDaCHS(tableName))
		return td and [
			(_getADQLName(f), makeFieldInfo(f)) for f in td if not f.hidden]


def _addTableMeta(translated, query, tree, table):
	"""adds various info items from query and its parsed tree to a
	result table.
	"""
	table.makeOriginal("info")
	table.addMeta("info", "", infoName="server", 
		infoValue=base.getConfig("web", "serverURL"))
	table.addMeta("info", "", infoName="sql_query", infoValue=translated)
	table.addMeta("info", "", infoName="query", infoValue=query)

	mth = base.caches.getMTH(None)
	sourceTables = tree.getContributingNames()
	# for 1-table queries, we've already copied the entire table metadata.
	# don't re-copy it.
	tableMetaCopied = len(sourceTables)==1

	tablesSeen = set()
	for tableName in sourceTables:
		if tableName in tablesSeen:
			continue
		tablesSeen.add(tableName)

		try:
			sourceTD = mth.getTableDefForTable(tableName)
			table.addMeta("info", 
				base.getMetaText(sourceTD.rd, "description", ""),
				infoName="src_res", 
				infoValue="Contains traces from resource %s"%(sourceTD.rd.sourceId))
			for m in sourceTD.iterMeta("rights", propagate=True):
				table.addMeta("info",
					m.getContent("text"),
					infoName="copyright", 
					infoValue="%s copyright or license"%(sourceTD.rd.sourceId))
			table.addMeta("info", 
				base.getMetaText(sourceTD, "description", "", propagate=False),
				infoName="src_table", 
				infoValue="Contains traces from table %s"%(
					sourceTD.getQName()))

			if not tableMetaCopied:
				for m in sourceTD.iterMeta("howtociteLink"):
					table.addMeta("howtociteLink", m)
				for m in sourceTD.iterMeta("source"):
					table.addMeta("source", m)

				for m in sourceTD.iterMeta("_associatedDatalinkService"):
					idColumn = sourceTD.getColumnByName(
						m.getMeta("idColumn").getContent())
					# ideally, look for column(s) that were built from idColumn
					# and are untainted (cave: join using)
					# for now, let's just fake it:
					try:
						destCol = table.tableDef.getColumnByName(idColumn.name)
						table.addMeta("_associatedDatalinkService", None)
						table.addMeta("_associatedDatalinkService.idColumn", 
							destCol.name)
						serviceId = m.getMeta("serviceId").getContent()
						if "#" not in serviceId:
							serviceId = "%s#%s"%(sourceTD.rd.sourceId, serviceId)
						table.addMeta("_associatedDatalinkService.serviceId", 
							serviceId)
					except base.NotFoundError:
						# User hasn't selected the column with the id.  No problem.
						pass
		except base.Error:
			# don't fail just because of funny metadata or tables not found
			pass


def _updateMatchLimits(tree, maxrec, hardLimit):
	"""instruments the ADQL tree for the user row set limit maxrec 
	and the system row set limit hard limit.

	maxrec is a match limit from the protocol level, as opposed to the
	setLimit from the ADQL TOP clause.  The rules of interaction between
	the two are documented inline below (it's messy).  
	
	This returns the overflow set limit.  If exactly this many rows
	are returned from he query, and overflow indicator should be set.
	"""
	tree.overflowLimit = None
	# First, fill in system defaults and make sure maxrec doesn't
	# exceed the caller's or the system's hard limits.
	if hardLimit is None:
		hardLimit = base.getConfig("async", "hardMAXREC")

	if maxrec is None:
		maxrec = base.getConfig("async", "defaultMAXREC")
	
	maxrec = min(maxrec, hardLimit)

	if tree.setLimit is None:
		# If no set limit has been passed in, put in maxrec and order
		# overflow indicators starting there.
		tree.setLimit = maxrec
		return maxrec

	elif maxrec>tree.setLimit:
		# If the set limit passed in is not larger than maxrec, there's
		# nothing we need to do, because we can never overflow
		return maxrec
	
	elif maxrec==tree.setLimit:
		# Special (but probably non-negligible) case: maxrec==set limit
		# we don't want to trigger an alarm and not touch the set limit either
		return maxrec+1
	
	else:
		# We have both maxrec and TOP, and maxrec<=TOP.  Set TOP to maxrec+1
		# and instruct to report overflows with maxrec+1 rows.  Let's hope
		# no one will mind an extra row here and there.
		tree.setLimit = maxrec+1
		return maxrec+1


def morphADQL(query, metaProfile=None, tdsForUploads=[], 
		maxrec=None, hardLimit=None):
	"""returns an postgres query and an (empty) result table for the
	ADQL in query.

	For an explanation of maxrec and hardLimit, as well as the
	additional table.tableDef.overflowLimit attribute on the returned table,
	see _updateMatchLimits above; this will always be an integer.
	"""
	ctx, t = adql.parseAnnotating(query,
		DaCHSFieldInfoGetter(metaProfile, tdsForUploads))

	table = rsc.TableForDef(_getTableDescForOutput(t))
	table.tableDef.overflowLimit = _updateMatchLimits(t, maxrec, hardLimit)
	if hardLimit and int(t.setLimit)>hardLimit:
		table.addMeta("_warning", "This service has a hard row limit"
			" of %s.  Your row limit was decreased to this value."%hardLimit)
		t.setLimit = str(hardLimit)

	morphStatus, morphedTree = adql.morphPG(t)
	for warning in morphStatus.warnings:
		table.addMeta("_warning", warning)

	# escape % to hide them form dbapi replacing
	translated = adql.flatten(morphedTree).replace("%", "%%")

	_addTableMeta(translated, query, t, table)

	return translated, table


def query(adqlQuery, timeout=15, metaProfile=None, tdsForUploads=[],
		externalLimit=None, hardLimit=None):
	"""returns a table for query (a string containing ADQL).

	This is a legacy wrapper for runTAPQuery used by the ADQL web form.
	Don't use it anywhere else.
	"""
	with base.getWritableUntrustedConn() as connection:
		qtable = runTAPQuery(adqlQuery, timeout, 
			connection, tdsForUploads, externalLimit, False)

		# instantiate the qtable; we want it all in one go
		resTable = rsc.InMemoryTable(
			qtable.tableDef,
			rows=list(qtable))

		qtable.cleanup()

	if len(resTable)==resTable.tableDef.overflowLimit:
		resTable.addMeta("_warning", "Query result probably incomplete due"
			" to the match limit kicking in.  Queries not providing a TOP"
			" clause will be furnished with an automatic TOP %s by the machinery,"
			" so adding a TOP clause with a higher number may help."%
			base.getConfig("adql", "webDefaultLimit"))

	return resTable


def runTAPQuery(query, timeout, connection, tdsForUploads, maxrec,
		autoClose=True):
	"""executes a TAP query and returns the result in a data instance.
	"""
	postgresParams = [
		# cursor tuple fraction only kicks in if we're actually using
		# cursors (which for psycopg2 only happens with named cursors).
		# Either way, we're going to eat all tuples, so tell that to
		# postgres.
		("cursor_tuple_fraction", 1),
		("statement_timeout", "%s ms"%int(timeout*1000))]

	try:
		pgQuery, tableTrunk = morphADQL(query,
			tdsForUploads=tdsForUploads, maxrec=maxrec)
		base.ui.notifyInfo("Sending to postgres: %s"%repr(pgQuery))

		# the following ugly hack works around a horrible planner
		# failure with q3c; we don't want to mess with the planner
		# unless we think that's necessary.  And otherwise wait
		# to migrate to pgsphere that hopefully doesn't confuse
		# the planner as much.
		if "q3c_" in pgQuery:
			postgresParams.append(
				('enable_seqscan', 'no'))

		resetTo = connection.configure(postgresParams)

		result = rsc.QueryTable(tableTrunk.tableDef, pgQuery, connection,
			autoClose=autoClose)
		result.meta_ = tableTrunk.meta_

		result.configureOnClose(resetTo)
	except:
		mapADQLErrors(*sys.exc_info())

	return result


def mapADQLErrors(excType, excValue, excTb):
	if (isinstance(excValue, adql.ParseException)
			or isinstance(excValue, adql.ParseSyntaxException)):
		raise base.ui.logOldExc(
			base.ValidationError("Could not parse your query: %s"%
				str(excValue), "query"))
	elif isinstance(excValue, adql.ColumnNotFound):
		raise base.ui.logOldExc(base.ValidationError("No such field known: %s"%
			str(excValue), "query"))
	elif isinstance(excValue, adql.AmbiguousColumn):
		raise base.ui.logOldExc(base.ValidationError("%s needs to be qualified."%
			str(excValue), "query"))
	elif isinstance(excValue, adql.Error):
		raise base.ui.logOldExc(base.ValidationError(str(excValue), "query"))
	else:
		svcs.mapDBErrors(excType, excValue, excTb)


class ADQLCore(svcs.Core, base.RestrictionMixin):
	"""A core taking an ADQL query from its query argument and returning the
	result of that query in a standard table.

	Since the columns returned depend on the query, the outputTable of an
	ADQL core must not be defined.
	"""
	name_ = "adqlCore"

	def wantsTableWidget(self):
		return True

	def run(self, service, inputTable, queryMeta):
		inRow = inputTable.getParamDict()
		queryString = inRow["query"]
		base.ui.notifyInfo("Incoming ADQL query: %s"%queryString)
		try:
			res = query(queryString, 
				timeout=queryMeta["timeout"], hardLimit=100000,
				externalLimit=queryMeta["dbLimit"])
# XXX Warning: We're returning the db connection to the connection
# pool here while we still have a named cursor on it.  This is
# risky because someone might fuzz with our connection later.
# However, postponing the return of the connection isn't nice
# either because then the renderer would have to manage the core's
# connections, which is ugly, too.
# I'm a bit at a loss for a good solution here.  Let's see how
# well the "don't care" scheme works out.  Maybe we need a "renderer closes
# connection" plan for this kind of streaming?
			res.noPostprocess = True
			queryMeta["Matched"] = len(res.rows)
			return res
		except:
			mapADQLErrors(*sys.exc_info())



################ region makers (maybe put these in a separate module later)
# The region maker should in general either call the parser with an ADQL
# fragment (see _makeSimbadRegion) or return a complete FieldInfoedNode
# including any info required with a node type of psqlLiteral (for
# postgres, let's see what happens if we want to support other DBs).
# 
# There are no guarantees that we won't parse out more symbols later,
# and hardcoded trees would break then.

import re

def _getRegionId(regionSpec, pat=re.compile("[A-Za-z_]+")):
	mat = pat.match(regionSpec)
	if mat:
		return mat.group()


################### local query interface #########################

def localquery():
	"""run the argument as an ADQL query.
	"""
	from gavo import rscdesc #noflake: cache registration
	from gavo import formats

	q = sys.argv[1]
	table = query(q, timeout=1000)
	formats.formatData("votable", table, sys.stdout.buffer)
