// 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 "exprs/vsearch.h"

#include <fmt/format.h>

#include <memory>

#include <roaring/roaring.hh>

#include "common/logging.h"

#include "common/status.h"

#include "core/column/column_const.h"

#include "exprs/function/function_search.h"

#include "exprs/vexpr_context.h"

#include "exprs/vliteral.h"

#include "exprs/vslot_ref.h"

#include "glog/logging.h"

#include "runtime/runtime_state.h"

#include "storage/index/inverted/inverted_index_reader.h"

#include "storage/schema.h"

#include "storage/segment/segment.h"

#include "storage/segment/variant/variant_column_reader.h"

namespace doris {

using namespace segment_v2;

namespace {

struct SearchInputBundle {

    std::unordered_map<std::string, IndexIterator*> iterators;

    std::unordered_map<std::string, IndexFieldNameAndTypePair> field_types;

    std::unordered_map<std::string, int> field_name_to_column_id;

    std::vector<int> column_indexes;

    ColumnsWithTypeAndName literal_args;

};

void add_search_binding_diagnostic(const IndexExecContext* index_context,

                                   const std::string& diagnostic) {

    VLOG_DEBUG << diagnostic;

    if (index_context == nullptr) {

        return;

    }

    const auto& index_query_context = index_context->get_index_query_context();

    if (index_query_context != nullptr && index_query_context->stats != nullptr) {

        index_query_context->stats->inverted_index_stats.add_binding_diagnostic(diagnostic);

    }

}

// A missing iterator is not evidence of a missing value: doc/sparse paths and

// old rowsets may contain values without an executable SEARCH index.

Status verify_missing_variant_path(const TSearchFieldBinding& binding, int column_index,

                                   IndexExecContext* index_context) {

    auto* segment = index_context->segment();

    if (segment == nullptr || !binding.__isset.parent_field_name ||

        !binding.__isset.subcolumn_path) {

        return Status::Error<ErrorCode::INVERTED_INDEX_NOT_SUPPORTED>(

                "SEARCH cannot establish missing path '{}'", binding.field_name);

    }

    const auto& read_schema = index_context->read_schema();

    DORIS_CHECK_GE(column_index, 0);

    DORIS_CHECK_LT(static_cast<size_t>(column_index), read_schema->num_column_ids());

    const auto& column = *read_schema->column(read_schema->column_id(column_index));

    const auto& opts = index_context->column_iter_opts();

    DORIS_CHECK(opts.stats != nullptr);

    const int32_t root_uid =

            column.parent_unique_id() >= 0 ? column.parent_unique_id() : column.unique_id();

    if (!segment->tablet_schema()->has_column_unique_id(root_uid)) {

        return Status::OK();

    }

    std::shared_ptr<ColumnReader> column_reader;

    Status st = segment->get_column_reader(root_uid, &column_reader, opts.stats, &opts.io_ctx);

    if (st.is<ErrorCode::NOT_FOUND>()) {

        // After DROP v(uid=1), ADD v(uid=2), an old segment cannot contain this scan's root.

        // Resolve by the current uid so historical values of the same name cannot match.

        return Status::OK();

    }

    RETURN_IF_ERROR(st);

    auto* reader = dynamic_cast<VariantColumnReader*>(column_reader.get());

    DORIS_CHECK(reader != nullptr);

    RETURN_IF_ERROR(reader->load_external_meta_once(opts.stats, &opts.io_ctx));

    const PathInData path(binding.subcolumn_path);

    const auto* stats = reader->get_stats();

    // Doc statistics enumerate stored paths without the sparse statistics limit. For example,

    // a segment containing only `string4` can prove `string5` absent even in doc mode.

    // An opaque root/ancestor value may contain the requested path, so it remains unavailable.

    bool in_doc = stats->existed_in_doc_value_column("") ||

                  stats->has_prefix_path_in_doc_value_column(path.get_path() + ".");

    std::string ancestor = path.get_path();

    while (!in_doc) {

        in_doc = stats->existed_in_doc_value_column(ancestor);

        const auto dot = ancestor.rfind('.');

        if (dot == std::string::npos) {

            break;

        }

        ancestor.resize(dot);

    }

    // Truncated sparse statistics cannot prove absence, nor can an existing unindexed path.

    if (reader->get_subcolumn_meta_by_path(path) != nullptr ||

        reader->has_prefix_path(path, opts.stats, &opts.io_ctx) ||

        reader->exist_in_sparse_column(path) || reader->is_exceeded_sparse_column_limit() ||

        in_doc || stats->has_nested_group) {

        return Status::Error<ErrorCode::INVERTED_INDEX_NOT_SUPPORTED>(

                "SEARCH index unavailable for Variant field '{}'", binding.field_name);

    }

    return Status::OK();

}

Status collect_slot_search_input(const VSearchExpr& expr, const VSlotRef& slot_ref,

                                 const TSearchFieldBinding* binding,

                                 IndexExecContext* index_context, SearchInputBundle* bundle) {

    DCHECK(index_context != nullptr);

    DCHECK(bundle != nullptr);

    // VSlotRef::column_id() is the scan-schema position used by IndexExecContext.

    const int column_index = slot_ref.column_id();

    const std::string field_name =

            binding != nullptr ? binding->field_name : slot_ref.column_name();

    const bool is_variant_subcolumn = binding != nullptr && binding->__isset.is_variant_subcolumn &&

                                      binding->is_variant_subcolumn;

    bundle->field_name_to_column_id[field_name] = column_index;

    auto* iterator = index_context->get_inverted_index_iterator_by_column_id(column_index);

    if (iterator == nullptr) {

        // For example, `data.items.message` has its own SlotRef in the scan schema. The

        // storage layer may inherit index metadata from `data`, but it still constructs a

        // child iterator whose stored field name contains the complete Variant path.

        if (is_variant_subcolumn) {

            add_search_binding_diagnostic(

                    index_context,

                    fmt::format("[VariantSearchBinding] phase=collect_inputs "

                                "result=no_iterator logical_field={} column_index={} "

                                "reason=slot_iterator_missing",

                                field_name, column_index));

        }

        if (!is_variant_subcolumn) {

            return Status::Error<ErrorCode::INVERTED_INDEX_NOT_SUPPORTED>(

                    "SEARCH index unavailable for field '{}'", field_name);

        }

        RETURN_IF_ERROR(verify_missing_variant_path(*binding, column_index, index_context));

        return Status::OK();

    }

    const auto* storage_name_type =

            index_context->get_storage_name_and_type_by_column_id(column_index);

    if (storage_name_type == nullptr) {

        return Status::InternalError("storage_name_type not found for column {} in {}",

                                     column_index, expr.expr_name());

    }

    bundle->iterators.emplace(field_name, iterator);

    bundle->field_types.emplace(field_name, *storage_name_type);

    bundle->column_indexes.emplace_back(column_index);

    if (is_variant_subcolumn) {

        add_search_binding_diagnostic(

                index_context,

                fmt::format("[VariantSearchBinding] phase=collect_inputs "

                            "result=direct_iterator logical_field={} column_index={} "

                            "stored_field={}",

                            field_name, column_index, storage_name_type->first));

    }

    return Status::OK();

}

const VSlotRef& variant_root_slot(const VExpr& expr) {

    const VExpr* root = &expr;

    while (root->fn().name.function_name == "element_at") {

        DORIS_CHECK(!root->children().empty());

        root = root->children().front().get();

    }

    DORIS_CHECK(root->is_slot_ref());

    return *assert_cast<const VSlotRef*>(root);

}

Status collect_search_inputs(const VSearchExpr& expr, VExprContext* context,

                             SearchInputBundle* bundle) {

    DCHECK(bundle != nullptr);

    auto index_context = context->get_index_context();

    if (index_context == nullptr) {

        LOG(WARNING) << "collect_search_inputs: No inverted index context available";

        return Status::InternalError("No inverted index context available");

    }

    const auto& search_param = expr.get_search_param();

    const auto& field_bindings = search_param.field_bindings;

    size_t child_index = 0;

    for (const auto& child : expr.children()) {

        if (child->is_slot_ref()) {

            auto* column_slot_ref = assert_cast<VSlotRef*>(child.get());

            const TSearchFieldBinding* binding =

                    child_index < field_bindings.size() ? &field_bindings[child_index] : nullptr;

            RETURN_IF_ERROR(collect_slot_search_input(expr, *column_slot_ref, binding,

                                                      index_context.get(), bundle));

            ++child_index;

        } else if (child->is_literal()) {

            auto* literal = assert_cast<VLiteral*>(child.get());

            bundle->literal_args.emplace_back(literal->get_column_ptr(), literal->get_data_type(),

                                              literal->expr_name());

        } else {

            // Check if this is ElementAt expression (for variant subcolumn access)

            if (child->expr_name() == "element_at" && child_index < field_bindings.size() &&

                field_bindings[child_index].__isset.is_variant_subcolumn &&

                field_bindings[child_index].is_variant_subcolumn) {

                // Variant subcolumn not materialized - skip, will create empty BitSetQuery in function_search

                add_search_binding_diagnostic(

                        index_context.get(),

                        fmt::format("[VariantSearchBinding] phase=collect_inputs "

                                    "result=unmaterialized_element_at logical_field={} "

                                    "parent_field={} sub_path={} reason=no_slot_ref",

                                    field_bindings[child_index].field_name,

                                    field_bindings[child_index].__isset.parent_field_name

                                            ? field_bindings[child_index].parent_field_name

                                            : "",

                                    field_bindings[child_index].__isset.subcolumn_path

                                            ? field_bindings[child_index].subcolumn_path

                                            : ""));

                RETURN_IF_ERROR(verify_missing_variant_path(field_bindings[child_index],

                                                            variant_root_slot(*child).column_id(),

                                                            index_context.get()));

                ++child_index;

                continue;

            }

            // Not a supported child type

            return Status::InvalidArgument("Unsupported child node type: {}", child->expr_name());

        }

    }

    return Status::OK();

}

} // namespace

VSearchExpr::VSearchExpr(const TExprNode& node) : VExpr(node) {

    if (node.__isset.search_param) {

        _search_param = node.search_param;

        _original_dsl = _search_param.original_dsl;

    }

}

Status VSearchExpr::prepare(RuntimeState* state, const RowDescriptor& row_desc,

                            VExprContext* context) {

    RETURN_IF_ERROR(VExpr::prepare(state, row_desc, context));

    const auto& query_options = state->query_options();

    if (query_options.__isset.enable_inverted_index_query_cache) {

        _enable_cache = query_options.enable_inverted_index_query_cache;

    }

    return Status::OK();

}

const std::string& VSearchExpr::expr_name() const {

    static const std::string name = "VSearchExpr";

    return name;

}

Status VSearchExpr::execute_column(VExprContext* context, const Block* block, Selector* selector,

                                   size_t count, ColumnPtr& result_column) const {

    if (fast_execute(context, selector, count, result_column)) {

        return Status::OK();

    }

    return Status::InternalError("SearchExpr should not be executed without inverted index");

}

Status VSearchExpr::evaluate_inverted_index(VExprContext* context, uint32_t segment_num_rows) {

    if (_search_param.original_dsl.empty()) {

        return Status::InvalidArgument("search DSL is empty");

    }

    auto index_context = context->get_index_context();

    if (!index_context) {

        LOG(WARNING) << "VSearchExpr: No inverted index context available";

        return Status::OK();

    }

    SearchInputBundle bundle;

    RETURN_IF_ERROR(collect_search_inputs(*this, context, &bundle));

    VLOG_DEBUG << "VSearchExpr: bundle.iterators.size()=" << bundle.iterators.size();

    auto index_query_context = index_context->get_index_query_context();

    auto function = std::make_shared<FunctionSearch>();

    auto result_bitmap = InvertedIndexResultBitmap();

    auto status = function->evaluate_inverted_index_with_search_param(

            _search_param, bundle.field_types, bundle.iterators, segment_num_rows, result_bitmap,

            _enable_cache, index_context.get(), bundle.field_name_to_column_id,

            index_query_context);

    if (!status.ok()) {

        LOG(WARNING) << "VSearchExpr: Function evaluation failed: " << status.to_string();

        return status;

    }

    index_context->set_index_result_for_expr(this, result_bitmap);

    for (int column_index : bundle.column_indexes) {

        index_context->set_true_for_index_status(this, column_index);

    }

    return Status::OK();

}

} // namespace doris