/*-------------------------------------------------------------------------
 *
 * pg_ivm.c
 *	  incremental view maintenance extension
 *    Routines for user interfaces and callback functions
 *
 * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
 * Portions Copyright (c) 2022, IVM Development Group
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/table.h"
#include "access/xact.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_namespace_d.h"
#include "catalog/pg_trigger_d.h"
#include "commands/trigger.h"
#include "parser/analyze.h"
#include "parser/parser.h"
#include "parser/scansup.h"
#include "tcop/tcopprot.h"
#include "nodes/makefuncs.h"
#include "utils/syscache.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/regproc.h"
#include "utils/rel.h"
#include "utils/varlena.h"

#include "pg_ivm.h"

PG_MODULE_MAGIC;


static object_access_hook_type PrevObjectAccessHook = NULL;

void		_PG_init(void);

static void IvmXactCallback(XactEvent event, void *arg);
static void IvmSubXactCallback(SubXactEvent event, SubTransactionId mySubid,
							   SubTransactionId parentSubid, void *arg);
static void parseNameAndColumns(const char *string, List **names, List **colNames);

static void PgIvmObjectAccessHook(ObjectAccessType access, Oid classId,
								  Oid objectId, int subId, void *arg);

/* SQL callable functions */
PG_FUNCTION_INFO_V1(create_immv);
PG_FUNCTION_INFO_V1(refresh_immv);
PG_FUNCTION_INFO_V1(IVM_prevent_immv_change);
PG_FUNCTION_INFO_V1(get_immv_def);

/*
 * Call back functions for cleaning up
 */
static void
IvmXactCallback(XactEvent event, void *arg)
{
	if (event == XACT_EVENT_PRE_COMMIT)
		AtPreCommit_IVM();
	else if (event == XACT_EVENT_ABORT)
		AtAbort_IVM(InvalidSubTransactionId);
}

static void
IvmSubXactCallback(SubXactEvent event, SubTransactionId mySubid,
				   SubTransactionId parentSubid, void *arg)
{
	if (event == SUBXACT_EVENT_ABORT_SUB)
		AtAbort_IVM(mySubid);
}


/*
 * Module load callback
 */
void
_PG_init(void)
{
	RegisterXactCallback(IvmXactCallback, NULL);
	RegisterSubXactCallback(IvmSubXactCallback, NULL);

	PrevObjectAccessHook = object_access_hook;
	object_access_hook = PgIvmObjectAccessHook;
}

/*
 * Given a C string, parse it into a qualified relation name
 * followed by an optional parenthesized list of column names.
 */
static void
parseNameAndColumns(const char *string, List **names, List **colNames)
{
	char	   *rawname;
	char	   *ptr;
	char	   *ptr2;
	bool		in_quote;
	bool		has_colnames = false;
	List	   *cols;
	ListCell   *lc;

	/* We need a modifiable copy of the input string. */
	rawname = pstrdup(string);

	/* Scan to find the expected left paren; mustn't be quoted */
	in_quote = false;
	for (ptr = rawname; *ptr; ptr++)
	{
		if (*ptr == '"')
			in_quote = !in_quote;
		else if (*ptr == '(' && !in_quote)
		{
			has_colnames = true;
			break;
		}
	}

	/* Separate the name and parse it into a list */
	*ptr++ = '\0';
#if defined(PG_VERSION_NUM) && (PG_VERSION_NUM >= 160000)
	*names = stringToQualifiedNameList(rawname, NULL);
#else
	*names = stringToQualifiedNameList(rawname);
#endif

	if (!has_colnames)
		goto end;

	/* Check for the trailing right parenthesis and remove it */
	ptr2 = ptr + strlen(ptr);
	while (--ptr2 > ptr)
	{
		if (!scanner_isspace(*ptr2))
			break;
	}
	if (*ptr2 != ')')
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
				 errmsg("expected a right parenthesis")));

	*ptr2 = '\0';

	if (!SplitIdentifierString(ptr, ',', &cols))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_NAME),
				 errmsg("invalid name syntax")));

	if (list_length(cols) == 0)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
				 errmsg("must specify at least one column name")));

	foreach(lc, cols)
	{
        char       *colname = lfirst(lc);
		*colNames = lappend(*colNames, makeString(pstrdup(colname)));
	}

end:
	pfree(rawname);
}

/*
 * User interface for creating an IMMV
 */
Datum
create_immv(PG_FUNCTION_ARGS)
{
	text	*t_relname = PG_GETARG_TEXT_PP(0);
	text	*t_sql = PG_GETARG_TEXT_PP(1);
	char	*relname = text_to_cstring(t_relname);
	char	*sql = text_to_cstring(t_sql);
	List	*parsetree_list;
	RawStmt	*parsetree;
	Query	*query;
	QueryCompletion qc;
	List	*names = NIL;
	List	*colNames = NIL;

	ParseState *pstate = make_parsestate(NULL);
	CreateTableAsStmt *ctas;
	StringInfoData command_buf;

	parseNameAndColumns(relname, &names, &colNames);

	initStringInfo(&command_buf);
	appendStringInfo(&command_buf, "SELECT create_immv('%s' AS '%s');", relname, sql);
	appendStringInfo(&command_buf, "%s;", sql);
	pstate->p_sourcetext = command_buf.data;

	parsetree_list = pg_parse_query(sql);

	/* XXX: should we check t_sql before command_buf? */
	if (list_length(parsetree_list) != 1)
		elog(ERROR, "invalid view definition");

	parsetree = linitial_node(RawStmt, parsetree_list);

	/* view definition should specify SELECT query */
	if (!IsA(parsetree->stmt, SelectStmt))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("view definition must specify SELECT statement")));

	ctas = makeNode(CreateTableAsStmt);
	ctas->query = parsetree->stmt;
#if defined(PG_VERSION_NUM) && (PG_VERSION_NUM >= 140000)
	ctas->objtype = OBJECT_MATVIEW;
#else
	ctas->relkind = OBJECT_MATVIEW;
#endif
	ctas->is_select_into = false;
	ctas->into = makeNode(IntoClause);
	ctas->into->rel = makeRangeVarFromNameList(names);
	ctas->into->colNames = colNames;
	ctas->into->accessMethod = NULL;
	ctas->into->options = NIL;
	ctas->into->onCommit = ONCOMMIT_NOOP;
	ctas->into->tableSpaceName = NULL;
#if defined(PG_VERSION_NUM) && (PG_VERSION_NUM >= 180000)
	ctas->into->viewQuery = (Query *) parsetree->stmt;
#else
	ctas->into->viewQuery = parsetree->stmt;
#endif
	ctas->into->skipData = false;

	query = transformStmt(pstate, (Node *) ctas);
	Assert(query->commandType == CMD_UTILITY && IsA(query->utilityStmt, CreateTableAsStmt));

	ExecCreateImmv(pstate, (CreateTableAsStmt *) query->utilityStmt, &qc);

	PG_RETURN_INT64(qc.nprocessed);
}

/*
 * User interface for refreshing an IMMV
 */
Datum
refresh_immv(PG_FUNCTION_ARGS)
{
	text	*t_relname = PG_GETARG_TEXT_PP(0);
	bool	ispopulated = PG_GETARG_BOOL(1);
	char    *relname = text_to_cstring(t_relname);
	QueryCompletion qc;
	StringInfoData command_buf;

	initStringInfo(&command_buf);
	appendStringInfo(&command_buf, "SELECT refresh_immv('%s, %s);",
					 relname, ispopulated ? "true" : "false");

	ExecRefreshImmv(makeRangeVarFromNameList(textToQualifiedNameList(t_relname)),
					!ispopulated, command_buf.data, &qc);

	PG_RETURN_INT64(qc.nprocessed);
}

/*
 * Trigger function to prevent IMMV from being changed
 */
Datum
IVM_prevent_immv_change(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	Relation	rel = trigdata->tg_relation;

	if (!ImmvIncrementalMaintenanceIsEnabled())
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("cannot change materialized view \"%s\"",
						RelationGetRelationName(rel))));

	return PointerGetDatum(NULL);
}

/*
 * Create triggers to prevent IMMV from being changed
 */
void
CreateChangePreventTrigger(Oid matviewOid)
{
	ObjectAddress	refaddr;
	ObjectAddress	address;
	CreateTrigStmt *ivm_trigger;

	int16 types[4] = {TRIGGER_TYPE_INSERT, TRIGGER_TYPE_DELETE,
					  TRIGGER_TYPE_UPDATE, TRIGGER_TYPE_TRUNCATE};
	int i;

	refaddr.classId = RelationRelationId;
	refaddr.objectId = matviewOid;
	refaddr.objectSubId = 0;

	ivm_trigger = makeNode(CreateTrigStmt);
	ivm_trigger->relation = NULL;
	ivm_trigger->row = false;

	ivm_trigger->timing = TRIGGER_TYPE_BEFORE;
	ivm_trigger->trigname = "IVM_prevent_immv_change";
	ivm_trigger->funcname = PgIvmFuncName("IVM_prevent_immv_change");
	ivm_trigger->columns = NIL;
	ivm_trigger->transitionRels = NIL;
	ivm_trigger->whenClause = NULL;
	ivm_trigger->isconstraint = false;
	ivm_trigger->deferrable = false;
	ivm_trigger->initdeferred = false;
	ivm_trigger->constrrel = NULL;
	ivm_trigger->args = NIL;

	for (i = 0; i < 4; i++)
	{
		ivm_trigger->events = types[i];
		address = CreateTrigger(ivm_trigger, NULL, matviewOid, InvalidOid, InvalidOid,
							 InvalidOid, InvalidOid, InvalidOid, NULL, true, false);

		recordDependencyOn(&address, &refaddr, DEPENDENCY_AUTO);
	}

	/* Make changes-so-far visible */
	CommandCounterIncrement();
}

/*
 * Get relid of pg_ivm_immv
 */
Oid
PgIvmImmvRelationId(void)
{
	return RangeVarGetRelid(
		makeRangeVar("pgivm", "pg_ivm_immv", -1),
		AccessShareLock, true);
}

/*
 * Get relid of pg_ivm_immv's primary key
 */
Oid
PgIvmImmvPrimaryKeyIndexId(void)
{
	return RangeVarGetRelid(
		makeRangeVar("pgivm", "pg_ivm_immv_pkey", -1),
		AccessShareLock, true);
}

/*
 * Return the SELECT part of an IMMV
 */
Datum
get_immv_def(PG_FUNCTION_ARGS)
{
	Oid	matviewOid = PG_GETARG_OID(0);
	Relation matviewRel = NULL;
	Query *query = NULL;
	char *querystring = NULL;

	/* Make sure IMMV is a table. */
	if (get_rel_relkind(matviewOid) != RELKIND_RELATION)
		PG_RETURN_NULL();

	matviewRel = table_open(matviewOid, AccessShareLock);
	query = get_immv_query(matviewRel);
	if (query == NULL)
	{
		table_close(matviewRel, NoLock);
		PG_RETURN_NULL();
	}

	querystring = pg_ivm_get_viewdef(matviewRel, false);

	table_close(matviewRel, NoLock);
	PG_RETURN_TEXT_P(cstring_to_text(querystring));
}

/*
 * object_access_hook function for dropping an IMMV
 */
static void
PgIvmObjectAccessHook(ObjectAccessType access, Oid classId,
					  Oid objectId, int subId, void *arg)
{
	if (PrevObjectAccessHook)
		PrevObjectAccessHook(access, classId, objectId, subId, arg);

	if (access == OAT_DROP && classId == RelationRelationId && !OidIsValid(subId))
	{
		Relation pgIvmImmv;
		SysScanDesc scan;
		ScanKeyData key;
		HeapTuple tup;
		Oid pgIvmImmvOid = PgIvmImmvRelationId();
	
		Oid pgIvmImmvPkOid = PgIvmImmvPrimaryKeyIndexId();

		/*
		 * Index or table not yet created (so no IMMVs yet), already dropped
		 * (expect IMMVs also gone soon), or renamed.  It's not great that a
		 * rename of either object will silently break IMMVs, but that's
		 * better than ERROR below.
		 */
		if (pgIvmImmvPkOid == InvalidOid || pgIvmImmvOid == InvalidOid)
			return;
		
		pgIvmImmv = table_open(pgIvmImmvOid, AccessShareLock);
		ScanKeyInit(&key,
					Anum_pg_ivm_immv_immvrelid,
					BTEqualStrategyNumber, F_OIDEQ,
					ObjectIdGetDatum(objectId));
		scan = systable_beginscan(pgIvmImmv, pgIvmImmvPkOid,
								  true, NULL, 1, &key);

		tup = systable_getnext(scan);

		if (HeapTupleIsValid(tup))
			CatalogTupleDelete(pgIvmImmv, &tup->t_self);

		systable_endscan(scan);
		table_close(pgIvmImmv, NoLock);
	}
}

/*
 * isImmv
 *
 * Check if this is an IMMV from oid.
 */
bool
isImmv(Oid immv_oid)
{
	Relation pgIvmImmv = table_open(PgIvmImmvRelationId(), AccessShareLock);
	SysScanDesc scan;
	ScanKeyData key;
	HeapTuple tup;

	ScanKeyInit(&key,
			    Anum_pg_ivm_immv_immvrelid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(immv_oid));
	scan = systable_beginscan(pgIvmImmv, PgIvmImmvPrimaryKeyIndexId(),
								  true, NULL, 1, &key);
	tup = systable_getnext(scan);

	systable_endscan(scan);
	table_close(pgIvmImmv, NoLock);

	if (!HeapTupleIsValid(tup))
		return false;
	else
		return true;
}

/* PgIvmFuncName()
 * Build a properly-qualified reference to a pg_ivm internal function.
 */
List *
PgIvmFuncName(char *name)
{
    return list_make2(makeString("pgivm"), makeString(name));
}