/*
 * Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd.
 * Portions Copyright (c) 2012-2014, PostgreSQL Global Development Group
 *
 * openGauss is licensed under Mulan PSL v2.
 * You can use this software according to the terms and conditions of the Mulan PSL v2.
 * You may obtain a copy of Mulan PSL v2 at:
 *
 *          http://license.coscl.org.cn/MulanPSL2
 *
 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
 * See the Mulan PSL v2 for more details.
 * ---------------------------------------------------------------------------------------
 *
 * mppdb_decoding.cpp
 *        logical decoding output plugin (json)
 *
 *
 *
 * IDENTIFICATION
 *        contrib/mppdb_decoding/mppdb_decoding.cpp
 *
 * ---------------------------------------------------------------------------------------
 */
#include "postgres.h"
#include "knl/knl_variable.h"

#include "access/sysattr.h"

#include "catalog/pg_class.h"
#include "catalog/pg_type.h"

#include "nodes/parsenodes.h"

#include "replication/output_plugin.h"
#include "replication/logical.h"

#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/relcache.h"
#include "utils/syscache.h"
#include "utils/typcache.h"

#include "cjson/cJSON.h"

PG_MODULE_MAGIC;

/* These must be available to pg_dlsym() */
extern "C" void _PG_init(void);
extern "C" void _PG_output_plugin_init(OutputPluginCallbacks* cb);

typedef struct {
    MemoryContext context;
    bool include_xids;
    bool include_timestamp;
    bool skip_empty_xacts;
    bool xact_wrote_changes;
    bool only_local;
} TestDecodingData;

static void pg_decode_startup(LogicalDecodingContext* ctx, OutputPluginOptions* opt, bool is_init);
static void pg_decode_shutdown(LogicalDecodingContext* ctx);
static void pg_decode_begin_txn(LogicalDecodingContext* ctx, ReorderBufferTXN* txn);
static void pg_output_begin(
    LogicalDecodingContext* ctx, TestDecodingData* data, ReorderBufferTXN* txn, bool last_write);
static void pg_decode_commit_txn(LogicalDecodingContext* ctx, ReorderBufferTXN* txn, XLogRecPtr commit_lsn);
static void pg_decode_change(
    LogicalDecodingContext* ctx, ReorderBufferTXN* txn, Relation rel, ReorderBufferChange* change);
static bool pg_decode_filter(LogicalDecodingContext* ctx, RepOriginId origin_id);

void _PG_init(void)
{
    /* other plugins can perform things here */
}

/* specify output plugin callbacks */
void _PG_output_plugin_init(OutputPluginCallbacks* cb)
{
    AssertVariableIsOfType(&_PG_output_plugin_init, LogicalOutputPluginInit);

    cb->startup_cb = pg_decode_startup;
    cb->begin_cb = pg_decode_begin_txn;
    cb->change_cb = pg_decode_change;
    cb->commit_cb = pg_decode_commit_txn;
    cb->filter_by_origin_cb = pg_decode_filter;
    cb->shutdown_cb = pg_decode_shutdown;
}

/* initialize this plugin */
static void pg_decode_startup(LogicalDecodingContext* ctx, OutputPluginOptions* opt, bool is_init)
{
    ListCell* option = NULL;
    TestDecodingData* data = NULL;

    data = (TestDecodingData*)palloc0(sizeof(TestDecodingData));
    data->context = AllocSetContextCreate(ctx->context,
        "text conversion context",
        ALLOCSET_DEFAULT_MINSIZE,
        ALLOCSET_DEFAULT_INITSIZE,
        ALLOCSET_DEFAULT_MAXSIZE);
    data->include_xids = true;
    data->include_timestamp = false;
    data->skip_empty_xacts = false;
    data->only_local = true;

    ctx->output_plugin_private = data;

    opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;

    foreach (option, ctx->output_plugin_options) {
        DefElem* elem = (DefElem*)lfirst(option);

        Assert(elem->arg == NULL || IsA(elem->arg, String));

        if (strcmp(elem->defname, "include-xids") == 0) {
            /* if option does not provide a value, it means its value is true */
            if (elem->arg == NULL)
                data->include_xids = true;
            else if (!parse_bool(strVal(elem->arg), &data->include_xids))
                ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                        errmsg("could not parse value \"%s\" for parameter \"%s\"", strVal(elem->arg), elem->defname)));
        } else if (strcmp(elem->defname, "include-timestamp") == 0) {
            if (elem->arg == NULL)
                data->include_timestamp = true;
            else if (!parse_bool(strVal(elem->arg), &data->include_timestamp))
                ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                        errmsg("could not parse value \"%s\" for parameter \"%s\"", strVal(elem->arg), elem->defname)));
        } else if (strcmp(elem->defname, "force-binary") == 0) {
            bool force_binary = false;

            if (elem->arg == NULL)
                continue;
            else if (!parse_bool(strVal(elem->arg), &force_binary))
                ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                        errmsg("could not parse value \"%s\" for parameter \"%s\"", strVal(elem->arg), elem->defname)));

            if (force_binary)
                opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
        } else if (strcmp(elem->defname, "skip-empty-xacts") == 0) {

            if (elem->arg == NULL)
                data->skip_empty_xacts = true;
            else if (!parse_bool(strVal(elem->arg), &data->skip_empty_xacts))
                ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                        errmsg("could not parse value \"%s\" for parameter \"%s\"", strVal(elem->arg), elem->defname)));
        } else if (strcmp(elem->defname, "only-local") == 0) {

            if (elem->arg == NULL)
                data->only_local = true;
            else if (!parse_bool(strVal(elem->arg), &data->only_local))
                ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                        errmsg("could not parse value \"%s\" for parameter \"%s\"", strVal(elem->arg), elem->defname)));
        } else {
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                    errmsg(
                        "option \"%s\" = \"%s\" is unknown", elem->defname, elem->arg ? strVal(elem->arg) : "(null)")));
        }
    }
}

/* cleanup this plugin's resources */
static void pg_decode_shutdown(LogicalDecodingContext* ctx)
{
    TestDecodingData* data = (TestDecodingData*)ctx->output_plugin_private;

    /* cleanup our own resources via memory context reset */
    MemoryContextDelete(data->context);
}

/* BEGIN callback */
static void pg_decode_begin_txn(LogicalDecodingContext* ctx, ReorderBufferTXN* txn)
{
    TestDecodingData* data = (TestDecodingData*)ctx->output_plugin_private;

    data->xact_wrote_changes = false;
    if (data->skip_empty_xacts)
        return;

    pg_output_begin(ctx, data, txn, true);
}

static void pg_output_begin(LogicalDecodingContext* ctx, TestDecodingData* data, ReorderBufferTXN* txn, bool last_write)
{
    OutputPluginPrepareWrite(ctx, last_write);
    if (data->include_xids)
        appendStringInfo(ctx->out, "BEGIN %lu", txn->xid);
    else
        appendStringInfoString(ctx->out, "BEGIN");
    OutputPluginWrite(ctx, last_write);
}

/* COMMIT callback */
static void pg_decode_commit_txn(LogicalDecodingContext* ctx, ReorderBufferTXN* txn, XLogRecPtr commit_lsn)
{
    TestDecodingData* data = (TestDecodingData*)ctx->output_plugin_private;

    if (data->skip_empty_xacts && !data->xact_wrote_changes)
        return;

    OutputPluginPrepareWrite(ctx, true);
    if (data->include_xids)
        appendStringInfo(ctx->out, "COMMIT %lu", txn->xid);
    else
        appendStringInfoString(ctx->out, "COMMIT");

    if (data->include_timestamp)
        appendStringInfo(ctx->out, " (at %s)", timestamptz_to_str(txn->commit_time));
    appendStringInfo(ctx->out, " CSN %lu", txn->csn);

    OutputPluginWrite(ctx, true);
}

static bool pg_decode_filter(LogicalDecodingContext* ctx, RepOriginId origin_id)
{
    TestDecodingData* data = (TestDecodingData*)ctx->output_plugin_private;

    if (data->only_local && origin_id != InvalidRepOriginId)
        return true;
    return false;
}

/*
 * Print literal `outputstr' already represented as string of type `typid'
 * into stringbuf `s'.
 *
 * Some builtin types aren't quoted, the rest is quoted. Escaping is done as
 * if u_sess->parser_cxt.standard_conforming_strings were enabled.
 */
static void print_literal(StringInfo s, Oid typid, char* outputstr)
{
    const char* valptr = NULL;

    switch (typid) {
        case INT1OID:
        case INT2OID:
        case INT4OID:
        case INT8OID:
        case OIDOID:
        case FLOAT4OID:
        case FLOAT8OID:
        case NUMERICOID:
            /* NB: We don't care about Inf, NaN et al. */
            appendStringInfoString(s, outputstr);
            break;

        case BITOID:
        case VARBITOID:
            appendStringInfo(s, "B'%s'", outputstr);
            break;

        case BOOLOID:
            if (strcmp(outputstr, "t") == 0)
                appendStringInfoString(s, "true");
            else
                appendStringInfoString(s, "false");
            break;

        default:
            appendStringInfoChar(s, '\'');
            for (valptr = outputstr; *valptr; valptr++) {
                char ch = *valptr;

                if (SQL_STR_DOUBLE(ch, false))
                    appendStringInfoChar(s, ch);
                appendStringInfoChar(s, ch);
            }
            appendStringInfoChar(s, '\'');
            break;
    }
}

/* print the tuple 'tuple' into the StringInfo s */
static void tuple_to_jsoninfo(
    cJSON* cols_name, cJSON* cols_type, cJSON* cols_val, TupleDesc tupdesc, HeapTuple tuple, bool skip_nulls)
{
    if (HEAP_TUPLE_IS_COMPRESSED(tuple->t_data))
        return;
    if ((int)HeapTupleHeaderGetNatts(tuple->t_data, tupdesc) > tupdesc->natts)
        return;

    int natt;

    /* print all columns individually */
    for (natt = 0; natt < tupdesc->natts; natt++) {
        Form_pg_attribute attr; /* the attribute itself */
        Oid typid;              /* type of current attribute */
        Oid typoutput;          /* output function */
        bool typisvarlena = false;
        Datum origval;       /* possibly toasted Datum */
        bool isnull = false; /* column is null? */

        attr = tupdesc->attrs[natt];

        /*
         * don't print dropped columns, we can't be sure everything is
         * available for them
         */
        if (attr->attisdropped)
            continue;

        /*
         * Don't print system columns, oid will already have been printed if
         * present.
         */
        if (attr->attnum < 0)
            continue;

        typid = attr->atttypid;

        /* get Datum from tuple */
        origval = heap_getattr(tuple, natt + 1, tupdesc, &isnull);

        if (isnull && skip_nulls)
            continue;

        /* print attribute name */

        cJSON* col_name = cJSON_CreateString(quote_identifier(NameStr(attr->attname)));
        cJSON_AddItemToArray(cols_name, col_name);

        /* print attribute type */
        if (cols_type != NULL) {
            cJSON* col_type = cJSON_CreateString(format_type_be(typid));
            cJSON_AddItemToArray(cols_type, col_type);
        }

        /* query output function */
        getTypeOutputInfo(typid, &typoutput, &typisvarlena);

        /* print separator */
        StringInfo val_str = makeStringInfo();
        /* print data */
        if (isnull)
            appendStringInfoString(val_str, "null");
        else if (typisvarlena && VARATT_IS_EXTERNAL_ONDISK_B(origval))
            appendStringInfoString(val_str, "unchanged-toast-datum");
        else if (!typisvarlena)
            print_literal(val_str, typid, OidOutputFunctionCall(typoutput, origval));
        else {
            Datum val; /* definitely detoasted Datum */
            val = PointerGetDatum(PG_DETOAST_DATUM(origval));
            print_literal(val_str, typid, OidOutputFunctionCall(typoutput, val));
        }
        cJSON* col_val = cJSON_CreateString(val_str->data);
        cJSON_AddItemToArray(cols_val, col_val);
    }
}
/*
 * callback for individual changed tuples
 */
static void pg_decode_change(
    LogicalDecodingContext* ctx, ReorderBufferTXN* txn, Relation relation, ReorderBufferChange* change)
{
    TestDecodingData* data = NULL;
    Form_pg_class class_form;
    TupleDesc tupdesc;
    MemoryContext old;
    char* res = NULL;
    data = (TestDecodingData*)ctx->output_plugin_private;
    u_sess->attr.attr_common.extra_float_digits = 0;

    /* output BEGIN if we haven't yet */
    if (data->skip_empty_xacts && !data->xact_wrote_changes) {
        pg_output_begin(ctx, data, txn, false);
    }
    data->xact_wrote_changes = true;

    class_form = RelationGetForm(relation);
    tupdesc = RelationGetDescr(relation);

    /* Avoid leaking memory by using and resetting our own context */
    old = MemoryContextSwitchTo(data->context);

    OutputPluginPrepareWrite(ctx, true);

    cJSON* root = cJSON_CreateObject();
    cJSON* table_name = cJSON_CreateString(quote_qualified_identifier(
        get_namespace_name(get_rel_namespace(RelationGetRelid(relation))), NameStr(class_form->relname)));
    cJSON_AddItemToObject(root, "table_name", table_name);

    cJSON* op_type = NULL;
    cJSON* columns_val = cJSON_CreateArray();
    cJSON* columns_name = cJSON_CreateArray();
    cJSON* columns_type = cJSON_CreateArray();
    cJSON* old_keys_name = cJSON_CreateArray();
    cJSON* old_keys_val = cJSON_CreateArray();
    cJSON* old_keys_type = cJSON_CreateArray();

    switch (change->action) {
        case REORDER_BUFFER_CHANGE_INSERT:
            op_type = cJSON_CreateString("INSERT");
            if (change->data.tp.newtuple != NULL) {
                tuple_to_jsoninfo(
                    columns_name, columns_type, columns_val, tupdesc, &change->data.tp.newtuple->tuple, false);
            }
            break;
        case REORDER_BUFFER_CHANGE_UPDATE:
            op_type = cJSON_CreateString("UPDATE");
            if (change->data.tp.oldtuple != NULL) {
                tuple_to_jsoninfo(
                    old_keys_name, old_keys_type, old_keys_val, tupdesc, &change->data.tp.oldtuple->tuple, true);
            }

            if (change->data.tp.newtuple != NULL) {
                tuple_to_jsoninfo(
                    columns_name, columns_type, columns_val, tupdesc, &change->data.tp.newtuple->tuple, false);
            }
            break;
        case REORDER_BUFFER_CHANGE_DELETE:
            op_type = cJSON_CreateString("DELETE");
            if (change->data.tp.oldtuple != NULL) {
                tuple_to_jsoninfo(
                    old_keys_name, old_keys_type, old_keys_val, tupdesc, &change->data.tp.oldtuple->tuple, true);
            }
            /* if there was no PK, we only know that a delete happened */
            break;
        default:
            Assert(false);
    }
    cJSON_AddItemToObject(root, "op_type", op_type);
    cJSON_AddItemToObject(root, "columns_name", columns_name);
    cJSON_AddItemToObject(root, "columns_type", columns_type);
    cJSON_AddItemToObject(root, "columns_val", columns_val);
    cJSON_AddItemToObject(root, "old_keys_name", old_keys_name);
    cJSON_AddItemToObject(root, "old_keys_type", old_keys_type);
    cJSON_AddItemToObject(root, "old_keys_val", old_keys_val);
    res = cJSON_PrintUnformatted(root);
    if (res != NULL)
        appendStringInfoString(ctx->out, res);
    cJSON_Delete(root);
    MemoryContextSwitchTo(old);
    MemoryContextReset(data->context);
    OutputPluginWrite(ctx, true);
}