path: root/source/20-codegen-compiler/SQLiteHelper.hpp

#pragma once

#include <fmt/format.h>
#include <sqlite3.h>
#include <cassert>
#include <chrono>
#include <cstddef>
#include <cstdint>
#include <sstream>
#include <stdexcept>
#include <string_view>
#include <tuple>
#include <type_traits>

struct SQLiteDatabase {
	sqlite3* database = nullptr;

	~SQLiteDatabase() {
		// NOTE: calling with NULL is a harmless no-op
		int result = sqlite3_close(database);
		assert(result == SQLITE_OK);
	}

	operator sqlite3*() const { return database; }
	sqlite3** operator&() { return &database; }
};

struct SQLiteStatement {
	sqlite3_stmt* stmt = nullptr;

	SQLiteStatement(const SQLiteStatement&) = delete;
	SQLiteStatement& operator=(const SQLiteStatement&) = delete;

	SQLiteStatement() = default;

	SQLiteStatement(sqlite3* database, std::string_view sql) {
		Initialize(database, sql);
	}

	~SQLiteStatement() {
		// NOTE: calling with NULL is a harmless no-op
		// NOTE: we don't care about the error code, because they are returned if the statement has errored in the most recent execution
		//       but deleting it will succeeed anyways
		sqlite3_finalize(stmt);
	}

	operator sqlite3_stmt*() const { return stmt; }
	sqlite3_stmt** operator&() { return &stmt; }

	void Initialize(sqlite3* database, std::string_view sql) {
		int result = sqlite3_prepare_v2(database, sql.data(), sql.size(), &stmt, nullptr);
		if (result != SQLITE_OK) {
			auto msg = fmt::format(
				"Failed to prepare SQLite3 statement, error message: {}",
				sqlite3_errmsg(sqlite3_db_handle(stmt)));
			throw std::runtime_error(msg);
		}
	}

	bool InitializeLazily(sqlite3* database, std::string_view sql) {
		if (!stmt) {
			Initialize(database, sql);
			return true;
		}
		return false;
	}
};

struct SQLiteRunningStatement {
	sqlite3_stmt* stmt;

	SQLiteRunningStatement(sqlite3_stmt* stmt)
		: stmt{ stmt } {
	}

	SQLiteRunningStatement(const SQLiteStatement& stmt)
		: stmt{ stmt.stmt } {
	}

	~SQLiteRunningStatement() {
		sqlite3_clear_bindings(stmt);
		sqlite3_reset(stmt);
	}

	void BindArgument(int index, int32_t value) {
		sqlite3_bind_int(stmt, index, (int)value);
	}

	void BindArgument(int index, uint32_t value) {
		sqlite3_bind_int(stmt, index, (int)value);
	}

	void BindArgument(int index, int64_t value) {
		sqlite3_bind_int64(stmt, index, value);
	}

	void BindArgument(int index, uint64_t value) {
		sqlite3_bind_int64(stmt, index, (int64_t)value);
	}

	void BindArgument(int index, const char* value) {
		sqlite3_bind_text(stmt, index, value, -1, nullptr);
	}

	void BindArgument(int index, std::string_view value) {
		sqlite3_bind_text(stmt, index, value.data(), value.size(), nullptr);
	}

	void BindArgument(int index, std::nullptr_t) {
		// Noop
	}

	template <typename... Ts>
	void BindArguments(Ts&&... args) {
		// NOTE: SQLite3 argument index starts at 1
		size_t idx = 1;
		auto HandleEachArgument = [this, &idx]<typename T>(T&& arg) {
			BindArgument(idx, std::forward<T>(arg));
			++idx;
		};
		(HandleEachArgument(std::forward<Ts>(args)), ...);
	}

	int Step() {
		return sqlite3_step(stmt);
	}

	void StepAndCheck(int forErr) {
		int err = sqlite3_step(stmt);
		assert(err == forErr);
	}

	int StepAndCheckError() {
		int err = sqlite3_step(stmt);
		if (err != SQLITE_DONE || err != SQLITE_ROW) {
			auto msg = fmt::format(
				"Error {} executing SQLite3 statement, error message: {}",
				sqlite3_errstr(err),
				sqlite3_errmsg(sqlite3_db_handle(stmt)));
			throw std::runtime_error(msg);
		}
		return err;
	}

	void StepUntilDone() {
		while (true) {
			int err = sqlite3_step(stmt);
			// SQLITE_OK is never returned for sqlite3_step() //TODO fact check this
			if (err == SQLITE_DONE) {
				break;
			}
			if (err == SQLITE_ROW) {
				continue;
			}

			auto msg = fmt::format(
				"Error {} executing SQLite3 statement, error message: {}",
				sqlite3_errstr(err),
				sqlite3_errmsg(sqlite3_db_handle(stmt)));
			throw std::runtime_error(msg);
		}
	}

	using TimePoint = std::chrono::time_point<std::chrono::system_clock>;
	using TpFromUnixTimestamp = std::pair<TimePoint, int64_t>;
	using TpFromDateTime = std::pair<TimePoint, const char*>;

	// TODO replace with overloads?
	template <typename T>
	auto ResultColumn(int column) const {
		if constexpr (std::is_enum_v<T>) {
			auto value = sqlite3_column_int64(stmt, column);
			return static_cast<T>(value);
		} else if constexpr (std::is_same_v<T, int> || std::is_same_v<T, bool>) {
			return (T)sqlite3_column_int(stmt, column);
		} else if constexpr (std::is_same_v<T, int64_t>) {
			return (T)sqlite3_column_int64(stmt, column);
		} else if constexpr (std::is_same_v<T, const char*>) {
			return (const char*)sqlite3_column_text(stmt, column);
		} else if constexpr (std::is_same_v<T, std::string> || std::is_same_v<T, std::string_view>) {
			// SQLite3 uses `unsigned char` to represent UTF-8 code units, on all platforms we care about this is the same as plain `char`
			auto cstr = (const char*)sqlite3_column_text(stmt, column);
			// For std::string_view, this finds size based on null terminator and stores reference to pointer
			// For std::string, this also allocates buffer and copies `cstr` content
			return T(cstr);
		} else if constexpr (std::is_same_v<T, TpFromUnixTimestamp>) {
			auto unixTimestamp = sqlite3_column_int64(stmt, column);
			auto chrono = std::chrono::seconds(unixTimestamp);
			return TimePoint(chrono);
		} else if constexpr (std::is_same_v<T, TpFromDateTime>) {
			// TODO wait for libstdc++ and libc++ implement c++20 std::chrono addition
#ifdef _MSC_VER
			auto datetime = (const char*)sqlite3_column_text(stmt, column);
			if (datetime) {
				std::stringstream ss(datetime);
				TimePoint timepoint;
				ss >> std::chrono::parse("%F %T", timepoint);
				return timepoint;
			} else {
				return TimePoint();
			}
#else
			static_assert(false && sizeof(T), "Unimplemented");
#endif
		} else {
			static_assert(false && sizeof(T), "Unknown type");
		}
	}

	template <typename... Ts>
	auto ResultColumns() {
		// NOTE: SQLite3 column index starts at 0
		// NOTE: ((size_t)-1) + 1 == 0
		size_t idx = -1;
		// NOTE: std::make_tuple() -- variadic template function
		//       std::tuple() -- CTAD constructor
		//       Both of these cause make the comma operator unsequenced, not viable here
		return std::tuple{ (++idx, ResultColumn<Ts>(idx))... };
	}
};