pica/database/mysql/statement.cpp

//  SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
//  SPDX-License-Identifier: GPL-3.0-or-later

#include "statement.h"

#include <cstring>

#include "mysqld_error.h"

#include "database/exceptions.h"

static uint64_t TIME_LENGTH = sizeof(MYSQL_TIME);

MySQL::Statement::Statement(MYSQL* connection, const char* statement):
    stmt(mysql_stmt_init(connection)),
    param()
{
    int result = mysql_stmt_prepare(stmt.get(), statement, strlen(statement));
    if (result != 0)
        throw std::runtime_error(std::string("Error preparing statement: ") + mysql_stmt_error(stmt.get()));
}

void MySQL::Statement::bind(void* value, enum_field_types type, bool usigned) {
    MYSQL_BIND& result = param.emplace_back();
    std::memset(&result, 0, sizeof(result));

    result.buffer_type = type;
    result.buffer = value;

   switch (type) {
        case MYSQL_TYPE_STRING:
        case MYSQL_TYPE_VAR_STRING:
            result.buffer_length = strlen(static_cast<char*>(value));
            break;
        case MYSQL_TYPE_DATE:
            result.buffer_length = TIME_LENGTH;
            break;
        case MYSQL_TYPE_LONG:
        case MYSQL_TYPE_LONGLONG:
        case MYSQL_TYPE_SHORT:
        case MYSQL_TYPE_TINY:
                result.is_unsigned = usigned;
            break;
        default:
            throw std::runtime_error("Type: " + std::to_string(type) + " is not yet supported in bind");
            break;
    }
}

void MySQL::Statement::execute() {
    MYSQL_STMT* raw = stmt.get();
    int result = mysql_stmt_bind_param(raw, param.data());
    if (result != 0)
        throw std::runtime_error(std::string("Error binding statement: ") + mysql_stmt_error(raw));

    result = mysql_stmt_execute(raw);
    if (result != 0) {
        int errcode = mysql_stmt_errno(raw);
        std::string text = mysql_stmt_error(raw);
        switch (errcode) {
            case ER_DUP_ENTRY:
                throw Duplicate("Error executing statement: " + text);
            default:
                throw std::runtime_error("Error executing statement: " + text);
        }
    }
}

std::vector<std::vector<std::string>> MySQL::Statement::fetchResult() {
    MYSQL_STMT* raw = stmt.get();
    if (mysql_stmt_store_result(raw) != 0)
        throw std::runtime_error(std::string("Error fetching statement result: ") + mysql_stmt_error(raw));   //TODO not sure if it's valid here

    MYSQL_RES* meta = mysql_stmt_result_metadata(raw);
    if (meta == nullptr)
        throw std::runtime_error(std::string("Error fetching statement result: ") + mysql_stmt_error(raw));   //TODO not sure if it's valid here

    std::unique_ptr<MYSQL_RES, ResDeleter> mt(meta);
    unsigned int numColumns = mysql_num_fields(meta);
    MYSQL_BIND bind[numColumns];
    memset(bind, 0, sizeof(bind));

    std::vector<std::string> line(numColumns);
    std::vector<long unsigned int> lengths(numColumns);
    for (unsigned int i = 0; i < numColumns; ++i) {
        MYSQL_FIELD *field = mysql_fetch_field_direct(meta, i);

        switch (field->type) {
            case MYSQL_TYPE_STRING:
            case MYSQL_TYPE_VAR_STRING:
            case MYSQL_TYPE_VARCHAR:
                break;
            default:
                throw std::runtime_error("Unsupported data fetching statement result " + std::to_string(field->type));
        }
        line[i].resize(field->length);
        bind[i].buffer_type = field->type;
        bind[i].buffer = line[i].data();
        bind[i].buffer_length = field->length;
        bind[i].length = &lengths[i];
    }

    if (mysql_stmt_bind_result(raw, bind) != 0)
        throw std::runtime_error(std::string("Error binding on fetching statement result: ") + mysql_stmt_error(raw));

    std::vector<std::vector<std::string>> result;
    while (mysql_stmt_fetch(raw) == 0) {
        std::vector<std::string>& row = result.emplace_back(numColumns);
        for (unsigned int i = 0; i < numColumns; ++i)
            row[i] = std::string(line[i].data(), lengths[i]);
    }

    return result;
}