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./villagesql init    # initialize database and seed bundled extensions
./villagesql start   # start the server (default port 3307)
./villagesql status  # check the server is running
./villagesql connect # open a mysql shell
./villagesql stop    # stop the server

./villagesql init --password
./villagesql start

./villagesql --here init
./villagesql --here start

./villagesql veb add /path/to/my_extension.veb  # copy a .veb to the server
./villagesql veb ls                              # list available .veb files
./villagesql veb rm my_extension                # remove a .veb file

INSTALL EXTENSION my_extension;

#include <villagesql/vsql.h>

using namespace vsql;

void add_impl(IntArg a, IntArg b, IntResult out) {
  if (a.is_null() || b.is_null()) { out.set_null(); return; }
  out.set(a.value() + b.value());
}

// Registration is unchanged:
make_func<&add_impl>("add").returns(INT).param(INT).param(INT).build();

using namespace vsql;

void rot13_impl(CustomArg in, CustomResult out) {
  if (in.is_null()) { out.set_null(); return; }
  auto src = in.value();   // vsql::Span<const unsigned char>
  auto dst = out.buffer(); // vsql::Span<unsigned char>
  for (size_t i = 0; i < src.size(); i++) { dst[i] = transform(src[i]); }
  out.set_length(src.size());
}

#include <villagesql/vsql.h>
#include <optional>

using namespace vsql;

// State type: nullopt means no non-NULL rows seen yet.
using SumState = std::optional<long long>;

void my_clear(SumState &s) { s = std::nullopt; }
void my_acc(SumState &s, IntArg v) {
  if (!v.is_null()) s = s.value_or(0) + v.value();
}
void my_result(const SumState &s, IntResult out) {
  if (!s.has_value()) { out.set_null(); return; }
  out.set(s.value());
}

// Registration:
// make_aggregate_func<SumState, &my_result>("my_sum")
//     .returns(INT)
//     .param(INT)
//     .clear<&my_clear>()
//     .accumulate<&my_acc>()
//     .build()

using CountState = long long;
void count_clear(CountState &s) { s = 0; }
void count_acc(CountState &s, IntArg v) { if (!v.is_null()) s++; }
void count_result(const CountState &s, IntResult out) { out.set(s); }

#include <villagesql/vsql.h>
using namespace vsql;

struct CallCounter { long long n = 0; };

void ba_call_index_prerun(PrerunArgs, PrerunResult out) {
  out.set_user_data(new CallCounter{});
}

void ba_call_index(CallCounter &state, IntResult out) {
  state.n++;
  out.set(state.n);
}

void ba_call_index_postrun(PostrunArgs args) {
  args.delete_state<CallCounter>();
}

// Registration:
// make_func<&ba_call_index>("ba_call_index")
//     .returns(INT).no_params()
//     .prerun<&ba_call_index_prerun>()
//     .postrun<&ba_call_index_postrun>()
//     .build()

#include <villagesql/vsql.h>
#include <cstring>
using namespace vsql;

constexpr size_t kBytearrayLen = 4;

void ba_concat_all_prerun(PrerunArgs args, PrerunResult out) {
  if (args.size() == 0) {
    out.error("ba_concat_all requires at least one argument");
    return;
  }
  for (size_t i = 0; i < args.size(); i++) {
    auto t = args.type_at(i);
    if (!t.is_custom() && !t.is_str()) {
      out.error("ba_concat_all: argument " + std::to_string(i) +
                " must be BYTEARRAY");
      return;
    }
  }
  out.request_buffer_size(args.size() * kBytearrayLen);
}

void ba_concat_all(VarArgs args, StringResult out) {
  auto dst = out.buffer();
  size_t off = 0;
  for (auto a : args) {
    if (a.is_null() || !a.is_custom()) { out.set_null(); return; }
    auto bytes = a.as_custom();
    std::memcpy(dst.data() + off, bytes.data(), bytes.size());
    off += bytes.size();
  }
  out.set_length(off);
}

// Registration:
// make_func<&ba_concat_all>("ba_concat_all")
//     .returns(STRING).varargs()
//     .prerun<&ba_concat_all_prerun>()
//     .build()

VEF_GENERATE_REGISTRATION(
    make_extension()
        .func(make_func<&my_impl>("my_func").returns(INT).build()))

// Then define your own extern "C" vef_register/vef_unregister that call
// _vef_do_register() and optionally modify the result.

// Encode: string -> binary. Write the encoded bytes via out.buffer() and
// out.set_length(n); call out.set_null() for SQL NULL, out.warning(msg) for
// recoverable bad input, or out.error(msg) to abort the statement. Returning
// without calling any of these surfaces a default warning.
using TypeEncodeFunc = void (*)(std::string_view from, vsql::CustomResult out);

// Decode: binary -> string. Report the outcome by calling
// out.set_length(n), out.set(sv), out.set_null(), out.warning(msg), or
// out.error(msg). If none is called the wrapper falls back to a default
// "failed to decode value" ERROR.
using TypeDecodeFunc = void (*)(vsql::CustomArg in, vsql::StringResult out);

// Compare: returns -1, 0, or 1 (used for ORDER BY and indexes).
using TypeCompareFunc = int (*)(vsql::CustomArg a, vsql::CustomArg b);

// Hash: returns hash code (used for hash joins).
using TypeHashFunc = size_t (*)(vsql::CustomArg in);

#include <villagesql/vsql.h>

using namespace vsql;

static constexpr const char kMyTypeName[] = "MYTYPE";

constexpr auto MYTYPE =
    vsql::make_type<kMyTypeName>()
        .persisted_length(8)
        .max_decode_buffer_length(64)
        .from_string<&my_encode>()   // auto: "MYTYPE::from_string"
        .to_string<&my_decode>()     // auto: "MYTYPE::to_string"
        .compare<&my_compare>()      // auto: "MYTYPE::compare"
        .hash<&my_hash>()            // optional, auto: "MYTYPE::hash"
        .intrinsic_default_str("0")  // string-literal intrinsic default
        .build();

VEF_GENERATE_ENTRY_POINTS(
    make_extension()
        .type(MYTYPE))

// Fixed (no type parameters):
using IntrinsicDefaultFunc = std::string (*)(char *error_msg);

// Parameterized (receives cached parsed params):
template <typename P>
using IntrinsicDefaultWithParamsFunc = std::string (*)(const P &,
                                                       char *error_msg);

std::string mytype_default(const MyTypeParams &p, char * /*error_msg*/) {
  return /* build string representation based on p */;
}

struct MyTypeParams {
  int64_t dimension;
  static MyTypeParams parse(const std::map<std::string, std::string> &p) {
    return {.dimension = stoll(p.at("dimension"))};
  }
  static void to_strings(const MyTypeParams &p,
                         std::map<std::string, std::string> &out) {
    out["dimension"] = std::to_string(p.dimension);
  }
};

void mytype_encode(vsql::MaybeParams<MyTypeParams> &params,
                   std::string_view from, vsql::CustomResult out) {
  const MyTypeParams &p = params.value();  // is_known() is always true at runtime
  size_t bytes = (size_t)p.dimension * 4;
  auto buf = out.buffer();
  if (buf.size() < bytes) { out.error("MYTYPE: buffer too small"); return; }
  // ... parse from, write to buf ...
  out.set_length(bytes);
}

void mytype_decode(vsql::CustomArgWith<MyTypeParams> in,
                   vsql::StringResult out) {
  const MyTypeParams &p = in.params();
  // ... read p.dimension floats from in.value(), write to out.buffer() ...
  out.set_length(bytes_written);
}

int mytype_compare(vsql::CustomArgWith<MyTypeParams> a,
                   vsql::CustomArgWith<MyTypeParams> b) {
  // Returns -1, 0, or 1.
}

size_t mytype_hash(vsql::CustomArgWith<MyTypeParams> in) {
  // Returns hash code.
}

// Converts MYTYPE(N) integer syntax to a parameter map.
// Signature: IntToTypeParamsFunc from <villagesql/vsql.h>.
bool mytype_int_to_params_fn(int64_t value,
                             std::map<std::string, std::string> &params,
                             char *error_msg) {
  if (value <= 0) {
    snprintf(error_msg, VEF_MAX_ERROR_LEN,
             "MYTYPE: dimension must be a positive integer");
    return true;
  }
  params["dimension"] = std::to_string(value);
  return false;  // success
}

// Validates parameters and computes storage sizes.
// Signature: ResolveTypeParamsFunc from <villagesql/vsql.h>.
bool mytype_resolve_params_fn(const std::map<std::string, std::string> &params,
                              vsql::ResolvedTypeParams *result,
                              char *error_msg) {
  int64_t dim = std::stoll(params.at("dimension"));
  result->persisted_length = dim * 4;
  result->max_decode_buffer_length = 64;
  return false;  // success
}

static constexpr const char kMyTypeName[] = "MYTYPE";

// Maximum valid dimension for MYTYPE.
constexpr int64_t kMyTypeMaxDimension = 1024;  // your max valid dimension
// Upper bound on MYTYPE's persisted byte size across all valid params.
constexpr int64_t kMyTypeMaxPersistedLength = kMyTypeMaxDimension * 4;

constexpr auto MYTYPE =
    vsql::make_type<kMyTypeName>()
        .persisted_length(-1)
        .max_decode_buffer_length(16)
        .max_persisted_length(kMyTypeMaxPersistedLength)
        .params<MyTypeParams, &MyTypeParams::parse, &MyTypeParams::to_strings>()
        .int_to_params<&mytype_int_to_params_fn>()
        .resolve_params<&mytype_resolve_params_fn>()
        .from_string<&mytype_encode>()
        .to_string<&mytype_decode>()
        .compare<&mytype_compare>()
        .intrinsic_default_vdf("mytype_intrinsic_default")
        .build();

using namespace vsql;

VEF_GENERATE_ENTRY_POINTS(
    make_extension()
        .type(MYTYPE)
        .func(make_intrinsic_default<&mytype_default>(
            "mytype_intrinsic_default")))

DELIMITER //
CREATE PROCEDURE insert_complex(IN val COMPLEX)
BEGIN
  DECLARE tmp COMPLEX;
  SET tmp = val;
  INSERT INTO t1 VALUES (tmp);
END //
DELIMITER ;

SELECT EXTENSION_NAME, NEGOTIATED_PROTOCOL, REGISTRATION_JSON
FROM INFORMATION_SCHEMA.EXTENSION_REGISTRATION
WHERE EXTENSION_NAME = 'my_ext';

cd $BUILD_HOME
./mysql-test/mysql-test-run.pl --suite=/path/to/your/extension/test --parallel=auto

cd $BUILD_HOME
./mysql-test/mysql-test-run.pl --suite=/path/to/your/extension/test my_test_name

# Description of the test

INSTALL EXTENSION my_extension;

# ... Your Test Code Here ...
CREATE TABLE t1 (val MYTYPE);
INSERT INTO t1 VALUES ('some_value');
SELECT * FROM t1;
DROP TABLE t1;

UNINSTALL EXTENSION my_extension;

--replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR

cd $BUILD_HOME
./mysql-test/mysql-test-run.pl --verbose --suite=/path/to/your/extension/test my_new_test

# To surface LogVSQL() messages in the error log:
./mysql-test/mysql-test-run.pl --mysqld=--log-error-verbosity=3 \
    --suite=/path/to/your/extension/test my_new_test