/* CTL3D file probing and Pascal unit initialization from Code3. */

#include "tdkpin_multimedia.h"

#include "tdkpin_borland_files.h"
#include "tdkpin_borland_records.h"
#include "tdkpin_shortstrings.h"
#include "tdkpin_strings.h"

extern Win16FarPtr g_multimedia_procedures[11]; /* 1028:4750..477b */
extern HINSTANCE16 g_multimedia_module;         /* 1028:4781 */
extern uint8_t g_multimedia_initialized;        /* 1028:4784 */

enum {
    DGROUP_CTL3D_DLL = 0x0522,
    DGROUP_CTL3DV2_DLL = 0x052c,
    DGROUP_MULTIMEDIA_LIBRARY_PATH = 0x478d,
    DGROUP_SYSTEM_DIRECTORY = 0x47a4,
    DGROUP_CTL3D_FULL_SHORT = 0x486d,
    DGROUP_CTL3DV2_FULL_SHORT = 0x496d,
};

/*
 * 1010:0405 -- existence probe for one Pascal ShortString path.  A failed
 * open is consumed through IOResult and reported false.  A successful open is
 * closed, and any close failure follows the original RuntimeError path.
 */
bool multimedia_short_file_exists(Win16FarPtr short_name)
{
    uint8_t copied_name[256];
    uint8_t length = win16_read_u8(short_name);
    copied_name[0] = length;
    for (uint16_t index = 0; index < length; index++) {
        copied_name[index + 1] = win16_read_u8(
            win16_far_add_offset(short_name, (uint16_t)(index + 1)));
    }

    uint8_t record_bytes[128];
    Win16FarPtr copied_name_far = win16_stack_pointer(copied_name);
    Win16FarPtr record = win16_stack_pointer(record_bytes);
    borland_assign_file_short(copied_name_far, record);
    borland_open_generic_file(1, record);
    if (borland_take_io_result() != 0) {
        return false;
    }

    borland_close_generic_file(record);
    borland_require_io_success();
    return true;
}

static void construct_system_path(
    Win16FarPtr destination,
    Win16FarPtr file_name,
    Win16FarPtr temporary_directory,
    Win16FarPtr temporary_file)
{
    borland_c_to_short_string(
        temporary_directory,
        win16_dgroup_pointer(DGROUP_SYSTEM_DIRECTORY));
    borland_short_concat(
        temporary_directory,
        win16_relocated_code_pointer(3, 0x0470));
    borland_c_to_short_string(temporary_file, file_name);
    borland_short_concat(temporary_directory, temporary_file);
    borland_short_assign_truncated(
        destination, temporary_directory, 0xff);
}

/*
 * 1010:0472 -- initialize all CTL3D unit state and Windows-version policy.
 * The two 256-byte temporaries are Pascal ShortStrings.  The system-directory
 * paths remain ShortStrings at 486d/496d; only the selected DLL basename at
 * 478d is converted back to a NUL-terminated C string for LoadLibrary.
 */
void multimedia_initialize_runtime_unit(void)
{
    g_multimedia_system_directory_length = GetSystemDirectoryFar16(
        win16_dgroup_pointer(DGROUP_SYSTEM_DIRECTORY), 200);

    uint8_t directory_short[256];
    uint8_t file_short[256];
    Win16FarPtr directory = win16_stack_pointer(directory_short);
    Win16FarPtr file = win16_stack_pointer(file_short);

    construct_system_path(
        win16_dgroup_pointer(DGROUP_CTL3D_FULL_SHORT),
        win16_dgroup_pointer(DGROUP_CTL3D_DLL),
        directory,
        file);
    construct_system_path(
        win16_dgroup_pointer(DGROUP_CTL3DV2_FULL_SHORT),
        win16_dgroup_pointer(DGROUP_CTL3DV2_DLL),
        directory,
        file);

    if (g_multimedia_system_directory_length != 0) {
        borland_c_to_short_string(
            file, win16_dgroup_pointer(DGROUP_CTL3DV2_DLL));
        (void)borland_short_to_c_string(
            win16_dgroup_pointer(DGROUP_MULTIMEDIA_LIBRARY_PATH), file);

        if (!multimedia_short_file_exists(
                win16_dgroup_pointer(DGROUP_CTL3DV2_FULL_SHORT)) &&
            multimedia_short_file_exists(
                win16_dgroup_pointer(DGROUP_CTL3D_FULL_SHORT))) {
            borland_c_to_short_string(
                file, win16_dgroup_pointer(DGROUP_CTL3D_DLL));
            (void)borland_short_to_c_string(
                win16_dgroup_pointer(DGROUP_MULTIMEDIA_LIBRARY_PATH), file);
        }
    }

    for (uint16_t index = 0; index < 11; index++) {
        g_multimedia_procedures[index] = 0;
    }

    g_multimedia_windows_version = (uint16_t)GetVersion16();
    uint8_t major = (uint8_t)g_multimedia_windows_version;
    uint8_t minor = (uint8_t)(g_multimedia_windows_version >> 8);
    g_multimedia_legacy_windows = major == 3 && minor < 10;

    g_multimedia_auto_subclassed = 0;
    g_multimedia_argument_2 = 0;
    g_multimedia_argument_1 = 1;
    g_multimedia_module = 0;
    g_multimedia_pending = 0;
    g_multimedia_initialized = 0;
}