// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

#include "format/generic_reader.h"

#include <gen_cpp/PlanNodes_types.h>

#include <gen_cpp/Types_types.h>

namespace doris {

Status GenericReader::init_column_descriptors(

        const TFileScanRangeParams& params, const TFileRangeDesc& range,

        const std::vector<ColumnDescriptor>& column_descs, const TupleDescriptor* tuple_descriptor,

        const RowDescriptor* row_descriptor, RuntimeState* state, bool fill_partition_from_path,

        const std::unordered_map<std::string, std::tuple<std::string, const SlotDescriptor*>>&

                partition_col_descs,

        std::unordered_map<std::string, VExprContextSPtr>* out_missing_col_descs,

        std::unordered_set<std::string>* out_missing_cols,

        std::unordered_map<std::string, DataTypePtr>* out_name_to_col_type) {

    // 1. Get columns from reader (which columns exist in the file, which are missing)

    RETURN_IF_ERROR(get_columns(out_name_to_col_type, out_missing_cols));

    // 2. Build default value expressions for missing columns

    std::unordered_map<std::string, VExprContextSPtr> col_default_value_ctx;

    for (auto* slot_desc : tuple_descriptor->slots()) {

        auto it = params.default_value_of_src_slot.find(slot_desc->id());

        if (it != params.default_value_of_src_slot.end()) {

            VExprContextSPtr ctx;

            if (!it->second.nodes.empty()) {

                RETURN_IF_ERROR(VExpr::create_expr_tree(it->second, ctx));

                RETURN_IF_ERROR(ctx->prepare(state, *row_descriptor));

                RETURN_IF_ERROR(ctx->open(state));

            }

            col_default_value_ctx.emplace(slot_desc->col_name(), ctx);

        }

    }

    // 3. Build missing_col_descs from missing columns

    out_missing_col_descs->clear();

    for (const auto& col_desc : column_descs) {

        if (!col_desc.is_file_slot) {

            continue;

        }

        if (out_missing_cols->contains(col_desc.name) ||

            out_missing_cols->contains(to_lower(col_desc.name))) {

            auto it = col_default_value_ctx.find(col_desc.name);

            if (it != col_default_value_ctx.end()) {

                out_missing_col_descs->emplace(col_desc.name, it->second);

            } else {

                // No default value: fill with null

                out_missing_col_descs->emplace(col_desc.name, nullptr);

            }

        }

    }

    // 4. Call set_fill_columns on the reader

    if (fill_partition_from_path) {

        RETURN_IF_ERROR(set_fill_columns(partition_col_descs, *out_missing_col_descs));

    } else {

        RETURN_IF_ERROR(set_fill_columns({}, *out_missing_col_descs));

    }

    return Status::OK();

}

} // namespace doris