/*
 * findoidjoins.c
 *
 * Copyright (c) 2002-2012, PostgreSQL Global Development Group
 *
 * src/tools/findoidjoins/findoidjoins.c
 */
#include "postgres_fe.h"

#include "libpq-fe.h"
#include "pqexpbuffer.h"

int main(int argc, char** argv)
{
    PGconn* conn = NULL;
    PQExpBufferData sql;
    PGresult* res = NULL;
    PGresult* pkrel_res = NULL;
    PGresult* fkrel_res = NULL;
    char* fk_relname = NULL;
    char* fk_nspname = NULL;
    char* fk_attname = NULL;
    char* pk_relname = NULL;
    char* pk_nspname = NULL;
    int fk, pk; /* loop counters */

    if (argc != 2) {
        fprintf(stderr, "Usage:  %s database\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    initPQExpBuffer(&sql);

    appendPQExpBuffer(&sql, "dbname=%s", argv[1]);
    appendPQExpBuffer(&sql, "enable_ce=1");

    conn = PQconnectdb(sql.data);
    if (PQstatus(conn) == CONNECTION_BAD) {
        fprintf(stderr, "connection error:  %s\n", PQerrorMessage(conn));
        exit(EXIT_FAILURE);
    }

    /* Get a list of relations that have OIDs */

    printfPQExpBuffer(&sql,
        "%s",
        "SET search_path = public;"
        "SELECT c.relname, (SELECT nspname FROM "
        "pg_catalog.pg_namespace n WHERE n.oid = c.relnamespace) AS nspname "
        "FROM pg_catalog.pg_class c "
        "WHERE c.relkind = 'r' "
        "AND c.relhasoids "
        "ORDER BY nspname, c.relname");

    res = PQexec(conn, sql.data);
    if (!res || PQresultStatus(res) != PGRES_TUPLES_OK) {
        fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
        exit(EXIT_FAILURE);
    }
    pkrel_res = res;

    /* Get a list of columns of OID type (or any OID-alias type) */

    printfPQExpBuffer(&sql,
        "%s",
        "SELECT c.relname, "
        "(SELECT nspname FROM pg_catalog.pg_namespace n WHERE n.oid = c.relnamespace) AS nspname, "
        "a.attname "
        "FROM pg_catalog.pg_class c, pg_catalog.pg_attribute a "
        "WHERE a.attnum > 0 AND c.relkind = 'r' "
        "AND a.attrelid = c.oid "
        "AND a.atttypid IN ('pg_catalog.oid'::regtype, "
        " 'pg_catalog.regclass'::regtype, "
        " 'pg_catalog.regoper'::regtype, "
        " 'pg_catalog.regoperator'::regtype, "
        " 'pg_catalog.regproc'::regtype, "
        " 'pg_catalog.regprocedure'::regtype, "
        " 'pg_catalog.regtype'::regtype, "
        " 'pg_catalog.regconfig'::regtype, "
        " 'pg_catalog.regdictionary'::regtype) "
        "ORDER BY nspname, c.relname, a.attnum");

    res = PQexec(conn, sql.data);
    if (!res || PQresultStatus(res) != PGRES_TUPLES_OK) {
        fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
        exit(EXIT_FAILURE);
    }
    fkrel_res = res;

    /*
     * For each column and each relation-having-OIDs, look to see if the
     * column contains any values matching entries in the relation.
     */

    for (fk = 0; fk < PQntuples(fkrel_res); fk++) {
        fk_relname = PQgetvalue(fkrel_res, fk, 0);
        fk_nspname = PQgetvalue(fkrel_res, fk, 1);
        fk_attname = PQgetvalue(fkrel_res, fk, 2);

        for (pk = 0; pk < PQntuples(pkrel_res); pk++) {
            pk_relname = PQgetvalue(pkrel_res, pk, 0);
            pk_nspname = PQgetvalue(pkrel_res, pk, 1);

            printfPQExpBuffer(&sql,
                "SELECT	1 "
                "FROM \"%s\".\"%s\" t1, "
                "\"%s\".\"%s\" t2 "
                "WHERE t1.\"%s\"::pg_catalog.oid = t2.oid "
                "LIMIT 1",
                fk_nspname,
                fk_relname,
                pk_nspname,
                pk_relname,
                fk_attname);

            res = PQexec(conn, sql.data);
            if (!res || PQresultStatus(res) != PGRES_TUPLES_OK) {
                fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
                exit(EXIT_FAILURE);
            }

            if (PQntuples(res) != 0)
                printf("Join %s.%s.%s => %s.%s.oid\n", fk_nspname, fk_relname, fk_attname, pk_nspname, pk_relname);

            PQclear(res);
        }
    }

    PQclear(fkrel_res);

    /* Now, do the same for referencing columns that are arrays */

    /* Get a list of columns of OID-array type (or any OID-alias type) */

    printfPQExpBuffer(&sql,
        "%s",
        "SELECT c.relname, "
        "(SELECT nspname FROM pg_catalog.pg_namespace n WHERE n.oid = c.relnamespace) AS nspname, "
        "a.attname "
        "FROM pg_catalog.pg_class c, pg_catalog.pg_attribute a "
        "WHERE a.attnum > 0 AND c.relkind = 'r' "
        "AND a.attrelid = c.oid "
        "AND a.atttypid IN ('pg_catalog.oid[]'::regtype, "
        " 'pg_catalog.regclass[]'::regtype, "
        " 'pg_catalog.regoper[]'::regtype, "
        " 'pg_catalog.regoperator[]'::regtype, "
        " 'pg_catalog.regproc[]'::regtype, "
        " 'pg_catalog.regprocedure[]'::regtype, "
        " 'pg_catalog.regtype[]'::regtype, "
        " 'pg_catalog.regconfig[]'::regtype, "
        " 'pg_catalog.regdictionary[]'::regtype) "
        "ORDER BY nspname, c.relname, a.attnum");

    res = PQexec(conn, sql.data);
    if (!res || PQresultStatus(res) != PGRES_TUPLES_OK) {
        fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
        exit(EXIT_FAILURE);
    }
    fkrel_res = res;

    /*
     * For each column and each relation-having-OIDs, look to see if the
     * column contains any values matching entries in the relation.
     */

    for (fk = 0; fk < PQntuples(fkrel_res); fk++) {
        fk_relname = PQgetvalue(fkrel_res, fk, 0);
        fk_nspname = PQgetvalue(fkrel_res, fk, 1);
        fk_attname = PQgetvalue(fkrel_res, fk, 2);

        for (pk = 0; pk < PQntuples(pkrel_res); pk++) {
            pk_relname = PQgetvalue(pkrel_res, pk, 0);
            pk_nspname = PQgetvalue(pkrel_res, pk, 1);

            printfPQExpBuffer(&sql,
                "SELECT	1 "
                "FROM \"%s\".\"%s\" t1, "
                "\"%s\".\"%s\" t2 "
                "WHERE t2.oid = ANY(t1.\"%s\")"
                "LIMIT 1",
                fk_nspname,
                fk_relname,
                pk_nspname,
                pk_relname,
                fk_attname);

            res = PQexec(conn, sql.data);
            if (!res || PQresultStatus(res) != PGRES_TUPLES_OK) {
                fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
                exit(EXIT_FAILURE);
            }

            if (PQntuples(res) != 0)
                printf("Join %s.%s.%s []=> %s.%s.oid\n", fk_nspname, fk_relname, fk_attname, pk_nspname, pk_relname);

            PQclear(res);
        }
    }

    PQclear(fkrel_res);

    PQclear(pkrel_res);

    PQfinish(conn);

    termPQExpBuffer(&sql);

    exit(EXIT_SUCCESS);
}