// 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 "exec/scan/access_path_parser.h"

#include <fmt/format.h>

#include <algorithm>

#include <charconv>

#include <map>

#include <string>

#include <string_view>

#include <utility>

#include "common/cast_set.h"

#include "common/consts.h"

#include "core/assert_cast.h"

#include "core/data_type/data_type.h"

#include "core/data_type/data_type_array.h"

#include "core/data_type/data_type_map.h"

#include "core/data_type/data_type_nullable.h"

#include "core/data_type/data_type_struct.h"

#include "runtime/descriptors.h"

#include "util/string_util.h"

namespace doris {

namespace {

bool is_scanner_materialized_virtual_column(const std::string& column_name) {

    return column_name == BeConsts::ICEBERG_ROWID_COL;

}

bool parse_non_negative_int(std::string_view value, int32_t* result) {

    DORIS_CHECK(result != nullptr);

    int32_t parsed = -1;

    const auto* begin = value.data();

    const auto* end = begin + value.size();

    const auto [ptr, ec] = std::from_chars(begin, end, parsed);

    if (ec != std::errc() || ptr != end || parsed < 0) {

        return false;

    }

    *result = parsed;

    return true;

}

std::string access_path_to_string(const std::vector<std::string>& path) {

    return fmt::format("{}", fmt::join(path, "."));

}

format::ColumnDefinition* find_or_add_child(format::ColumnDefinition* parent, int32_t id,

                                            std::string name, DataTypePtr type) {

    DORIS_CHECK(parent != nullptr);

    for (auto& child : parent->children) {

        if ((child.has_identifier_field_id() && child.get_identifier_field_id() == id) ||

            child.name == name) {

            return &child;

        }

    }

    parent->children.push_back({

            .identifier = Field::create_field<TYPE_INT>(id),

            .name = std::move(name),

            .type = std::move(type),

            .children = {},

            .default_expr = nullptr,

            .is_partition_key = false,

    });

    return &parent->children.back();

}

void inherit_schema_metadata(format::ColumnDefinition* column,

                             const format::ColumnDefinition* schema_column) {

    if (column == nullptr || schema_column == nullptr) {

        return;

    }

    column->name_mapping = schema_column->name_mapping;

}

const format::ColumnDefinition* find_schema_child_by_path(

        const format::ColumnDefinition* schema_column, const std::string& child_path) {

    if (schema_column == nullptr) {

        return nullptr;

    }

    int32_t parsed_field_id = -1;

    if (parse_non_negative_int(child_path, &parsed_field_id)) {

        const auto child_it = std::ranges::find_if(

                schema_column->children, [&](const format::ColumnDefinition& child) {

                    return child.has_identifier_field_id() &&

                           child.get_identifier_field_id() == parsed_field_id;

                });

        return child_it == schema_column->children.end() ? nullptr : &*child_it;

    }

    const auto child_it = std::ranges::find_if(schema_column->children, [&](const auto& child) {

        if (to_lower(child.name) == to_lower(child_path)) {

            return true;

        }

        return std::ranges::any_of(child.name_mapping, [&](const std::string& alias) {

            return to_lower(alias) == to_lower(child_path);

        });

    });

    return child_it == schema_column->children.end() ? nullptr : &*child_it;

}

int32_t schema_field_id(const format::ColumnDefinition* schema_column) {

    if (schema_column == nullptr || !schema_column->has_identifier_field_id()) {

        return -1;

    }

    return schema_column->get_identifier_field_id();

}

int32_t schema_field_id_or(const format::ColumnDefinition* schema_column, int32_t fallback) {

    const auto field_id = schema_field_id(schema_column);

    return field_id >= 0 ? field_id : fallback;

}

std::string schema_field_name_or(const format::ColumnDefinition* schema_column,

                                 std::string fallback) {

    return schema_column == nullptr || schema_column->name.empty() ? std::move(fallback)

                                                                   : schema_column->name;

}

struct AccessPathNode {

    bool project_all = false;

    std::map<std::string, AccessPathNode> children;

};

void merge_access_path_node(AccessPathNode* dst, const AccessPathNode& src) {

    DORIS_CHECK(dst != nullptr);

    if (dst->project_all) {

        return;

    }

    if (src.project_all) {

        dst->project_all = true;

        dst->children.clear();

        return;

    }

    for (const auto& [path, child] : src.children) {

        merge_access_path_node(&dst->children[path], child);

    }

}

void insert_access_path(AccessPathNode* root, const std::vector<std::string>& path,

                        size_t path_idx) {

    DORIS_CHECK(root != nullptr);

    if (root->project_all) {

        return;

    }

    if (path_idx >= path.size()) {

        root->project_all = true;

        root->children.clear();

        return;

    }

    insert_access_path(&root->children[path[path_idx]], path, path_idx + 1);

}

Status build_nested_children_from_access_node(format::ColumnDefinition* column,

                                              const DataTypePtr& type, const AccessPathNode& node,

                                              const std::string& path,

                                              const format::ColumnDefinition* schema_column);

// Expand a full complex-column projection into table-schema children when the table format provides

// an external/current schema. Without this, `SELECT complex_col` or `SELECT *` leaves

// ColumnDefinition::children empty, so ColumnMapper treats the root complex column as a scalar

// mapping and later tries to cast the old file shape to the current table shape directly.

//

// Examples:

//   - STRUCT country/city projected from an old file STRUCT country/population/location should

//     create children country and city, so city can be materialized as missing/default.

//   - ARRAY<STRUCT<item, quantity>> should create the array element wrapper and then the element

//     struct children item and quantity.

//   - MAP<STRING, STRUCT<full_name, age>> should create semantic children key/value directly, then

//     expand the value struct children full_name and age. Do not introduce a physical entries

//     wrapper here: ColumnMapper and TableReader treat MAP children as [key, value].

Status build_all_nested_children_from_schema(format::ColumnDefinition* column,

                                             const DataTypePtr& type, const std::string& path,

                                             const format::ColumnDefinition* schema_column) {

    DORIS_CHECK(column != nullptr);

    const auto nested_type = remove_nullable(type);

    AccessPathNode project_all;

    project_all.project_all = true;

    switch (nested_type->get_primitive_type()) {

    case TYPE_STRUCT: {

        const auto& struct_type = assert_cast<const DataTypeStruct&>(*nested_type);

        for (size_t field_idx = 0; field_idx < struct_type.get_elements().size(); ++field_idx) {

            const auto field_name = struct_type.get_element_name(field_idx);

            const auto* schema_child = find_schema_child_by_path(schema_column, field_name);

            auto* child = find_or_add_child(

                    column, schema_field_id_or(schema_child, cast_set<int32_t>(field_idx)),

                    schema_field_name_or(schema_child, field_name),

                    struct_type.get_element(field_idx));

            inherit_schema_metadata(child, schema_child);

            RETURN_IF_ERROR(build_nested_children_from_access_node(

                    child, child->type, project_all, path + "." + child->name, schema_child));

        }

        return Status::OK();

    }

    case TYPE_ARRAY: {

        const auto& array_type = assert_cast<const DataTypeArray&>(*nested_type);

        const auto* element_schema = schema_column != nullptr && !schema_column->children.empty()

                                             ? &schema_column->children[0]

                                             : nullptr;

        auto* child = find_or_add_child(column, schema_field_id_or(element_schema, 0), "element",

                                        array_type.get_nested_type());

        inherit_schema_metadata(child, element_schema);

        return build_nested_children_from_access_node(child, child->type, project_all, path + ".*",

                                                      element_schema);

    }

    case TYPE_MAP: {

        const auto& map_type = assert_cast<const DataTypeMap&>(*nested_type);

        const auto* key_schema = schema_column != nullptr && !schema_column->children.empty()

                                         ? &schema_column->children[0]

                                         : nullptr;

        const auto* value_schema = schema_column != nullptr && schema_column->children.size() > 1

                                           ? &schema_column->children[1]

                                           : nullptr;

        auto* key_child = find_or_add_child(column, schema_field_id_or(key_schema, 0), "key",

                                            map_type.get_key_type());

        inherit_schema_metadata(key_child, key_schema);

        RETURN_IF_ERROR(build_nested_children_from_access_node(

                key_child, key_child->type, project_all, path + ".KEYS", key_schema));

        auto* value_child = find_or_add_child(column, schema_field_id_or(value_schema, 1), "value",

                                              map_type.get_value_type());

        inherit_schema_metadata(value_child, value_schema);

        RETURN_IF_ERROR(build_nested_children_from_access_node(

                value_child, value_child->type, project_all, path + ".VALUES", value_schema));

        return Status::OK();

    }

    default:

        return Status::OK();

    }

}

Status build_struct_children_from_access_node(format::ColumnDefinition* column,

                                              const DataTypeStruct& struct_type,

                                              const AccessPathNode& node, const std::string& path,

                                              const format::ColumnDefinition* schema_column) {

    DORIS_CHECK(column != nullptr);

    for (const auto& [child_path, child_node] : node.children) {

        // Struct children are resolved by name or schema field id. We do not treat a numeric

        // child token as a struct ordinal, because `col.0` becomes ambiguous once the struct

        // evolves. Position-based access needs a separate design if it is required later.

        if (child_path == "OFFSET" || child_path == "*" || child_path == "KEYS" ||

            child_path == "VALUES") {

            return Status::NotSupported(

                    "AccessPathParser does not support access path {} for slot {}",

                    path + "." + child_path, column->name);

        }

        // Prefer the table/schema ColumnDefinition because it carries field ids and aliases.

        // Fallback to the struct type name only for formats without external schema metadata.

        const auto* schema_child = find_schema_child_by_path(schema_column, child_path);

        int32_t field_id = schema_field_id(schema_child);

        std::string field_name = schema_child == nullptr ? child_path : schema_child->name;

        DataTypePtr field_type = schema_child == nullptr ? nullptr : schema_child->type;

        if (field_id < 0 || field_type == nullptr) {

            for (size_t field_idx = 0; field_idx < struct_type.get_elements().size(); ++field_idx) {

                if (to_lower(struct_type.get_element_name(field_idx)) == to_lower(field_name)) {

                    field_id = cast_set<int32_t>(field_idx);

                    field_name = struct_type.get_element_name(field_idx);

                    field_type = struct_type.get_element(field_idx);

                    break;

                }

            }

        }

        if (field_id < 0 || field_type == nullptr) {

            return Status::NotSupported(

                    "AccessPathParser does not support access path {} for slot {}",

                    path + "." + child_path, column->name);

        }

        // TODO: For TVF Parquet files without field ids, this fallback uses the struct ordinal as

        // the table child identifier. BY_NAME mapping should instead keep a string identifier and

        // let TableColumnMapper resolve the file-local child id from the Parquet schema.

        auto* child = find_or_add_child(column, field_id, field_name, field_type);

        inherit_schema_metadata(child, schema_child);

        RETURN_IF_ERROR(build_nested_children_from_access_node(

                child, child->type, child_node, path + "." + child_path, schema_child));

    }

    return Status::OK();

}

Status build_map_children_from_access_node(format::ColumnDefinition* column,

                                           const DataTypeMap& map_type, const AccessPathNode& node,

                                           const std::string& path,

                                           const format::ColumnDefinition* schema_column) {

    DORIS_CHECK(column != nullptr);

    AccessPathNode key_node;

    AccessPathNode value_node;

    bool need_key = false;

    bool need_value = false;

    for (const auto& [child_path, child_node] : node.children) {

        if (child_path == "OFFSET") {

            return Status::NotSupported(

                    "AccessPathParser does not support access path {} for slot {}",

                    path + "." + child_path, column->name);

        }

        if (child_path == "KEYS") {

            need_key = true;

            merge_access_path_node(&key_node, child_node);

            continue;

        }

        if (child_path == "VALUES") {

            need_key = true;

            key_node.project_all = true;

            key_node.children.clear();

            need_value = true;

            merge_access_path_node(&value_node, child_node);

            continue;

        }

        if (child_path == "*") {

            need_key = true;

            key_node.project_all = true;

            key_node.children.clear();

            need_value = true;

            merge_access_path_node(&value_node, child_node);

            continue;

        }

        return Status::NotSupported("AccessPathParser does not support access path {} for slot {}",

                                    path + "." + child_path, column->name);

    }

    if (need_key && !need_value) {

        // A key-only MAP projection is not independently materializable yet. FileScannerV2 can

        // describe a projection such as `m.KEYS`, but the downstream file block -> table block path

        // still builds a ColumnMap from key column + value column + offsets. If the value child is

        // omitted here, TableReader/ColumnMapper cannot reconstruct a valid table MAP column even

        // though the query only needs keys.

        //

        // Example:

        //   SELECT map_keys(m) FROM t;

        // or

        //   SELECT * FROM t WHERE array_contains(map_keys(m), 'k1');

        //

        // The access path only asks for `m.KEYS`, but the scan still has to read `m.VALUES` as a

        // temporary full projection until map materialization supports constructing a table MAP

        // from keys only.

        need_value = true;

        value_node.project_all = true;

        value_node.children.clear();

    }

    if (!need_key && !need_value) {

        return Status::OK();

    }

    const auto* key_schema = schema_column != nullptr && !schema_column->children.empty()

                                     ? &schema_column->children[0]

                                     : nullptr;

    const auto* value_schema = schema_column != nullptr && schema_column->children.size() > 1

                                       ? &schema_column->children[1]

                                       : nullptr;

    if (need_key) {

        auto* key_child = find_or_add_child(column, schema_field_id_or(key_schema, 0), "key",

                                            map_type.get_key_type());

        inherit_schema_metadata(key_child, key_schema);

        RETURN_IF_ERROR(build_nested_children_from_access_node(key_child, key_child->type, key_node,

                                                               path + ".KEYS", key_schema));

    }

    if (need_value) {

        auto* value_child = find_or_add_child(column, schema_field_id_or(value_schema, 1), "value",

                                              map_type.get_value_type());

        inherit_schema_metadata(value_child, value_schema);

        RETURN_IF_ERROR(build_nested_children_from_access_node(

                value_child, value_child->type, value_node, path + ".VALUES", value_schema));

    }

    return Status::OK();

}

Status build_nested_children_from_access_node(format::ColumnDefinition* column,

                                              const DataTypePtr& type, const AccessPathNode& node,

                                              const std::string& path,

                                              const format::ColumnDefinition* schema_column) {

    DORIS_CHECK(column != nullptr);

    if (node.project_all || node.children.empty()) {

        return build_all_nested_children_from_schema(column, type, path, schema_column);

    }

    const auto nested_type = remove_nullable(type);

    switch (nested_type->get_primitive_type()) {

    case TYPE_STRUCT:

        return build_struct_children_from_access_node(

                column, assert_cast<const DataTypeStruct&>(*nested_type), node, path,

                schema_column);

    case TYPE_ARRAY: {

        if (node.children.size() != 1 || !node.children.contains("*")) {

            return Status::NotSupported(

                    "AccessPathParser does not support access path {} for slot {}", path,

                    column->name);

        }

        const auto& array_type = assert_cast<const DataTypeArray&>(*nested_type);

        const auto* element_schema = schema_column != nullptr && !schema_column->children.empty()

                                             ? &schema_column->children[0]

                                             : nullptr;

        auto* child = find_or_add_child(column, schema_field_id_or(element_schema, 0), "element",

                                        array_type.get_nested_type());

        inherit_schema_metadata(child, element_schema);

        return build_nested_children_from_access_node(child, child->type, node.children.at("*"),

                                                      path + ".*", element_schema);

    }

    case TYPE_MAP:

        return build_map_children_from_access_node(

                column, assert_cast<const DataTypeMap&>(*nested_type), node, path, schema_column);

    default:

        return Status::NotSupported("AccessPathParser does not support access path {} for slot {}",

                                    path, column->name);

    }

}

} // namespace

Status AccessPathParser::build_nested_children(format::ColumnDefinition* column,

                                               const std::vector<TColumnAccessPath>& access_paths,

                                               const format::ColumnDefinition* schema_column) {

    DORIS_CHECK(column != nullptr);

    if (is_scanner_materialized_virtual_column(column->name)) {

        return Status::OK();

    }

    if (!is_complex_type(remove_nullable(column->type)->get_primitive_type())) {

        return Status::OK();

    }

    AccessPathNode root;

    // Build tree for AccessPathNode.

    // For example, for access paths ["a.b", "a.c", "d"], the tree will be:

    // root

    // ├── a

    // │   ├── b

    // │   └── c

    // └── d

    for (const auto& access_path : access_paths) {

        // TODO: Support META access paths if needed. Currently AccessPathParser only supports

        // DATA access paths.

        if (access_path.type != TAccessPathType::DATA || !access_path.__isset.data_access_path) {

            return Status::NotSupported(

                    "AccessPathParser only supports DATA access paths for slot {}", column->name);

        }

        const auto& path = access_path.data_access_path.path;

        if (path.empty()) {

            insert_access_path(&root, path, 0);

            continue;

        }

        int32_t top_level_id = -1;

        if (to_lower(path.front()) != to_lower(column->name) &&

            (!parse_non_negative_int(path.front(), &top_level_id) ||

             !column->has_identifier_field_id() ||

             top_level_id != column->get_identifier_field_id())) {

            return Status::NotSupported("AccessPathParser access path {} does not match slot {}",

                                        access_path_to_string(path), column->name);

        }

        insert_access_path(&root, path, 1);

    }

    // Recursively build nested children for the column based on the AccessPathNode tree.

    return build_nested_children_from_access_node(column, column->type, root, column->name,

                                                  schema_column);

}

Status AccessPathParser::build_nested_children(format::ColumnDefinition* column,

                                               const SlotDescriptor* slot_desc,

                                               const format::ColumnDefinition* schema_column) {

    DORIS_CHECK(column != nullptr);

    DORIS_CHECK(slot_desc != nullptr);

    return build_nested_children(column, slot_desc->all_access_paths(), schema_column);

}

} // namespace doris