/* Dynamic Win16 multimedia helper DLL lifecycle from Code3. */

#include "tdkpin_multimedia.h"

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

static const char *const multimedia_procedure_names[11] = {
    "CTL3DAUTOSUBCLASS",
    "CTL3DCOLORCHANGE",
    "CTL3DCTLCOLOREX",
    "CTL3DENABLED",
    "CTL3DDLGFRAMEPAINT",
    "CTL3DGETVER",
    "CTL3DREGISTER",
    "CTL3DSUBCLASSDLG",
    "CTL3DSUBCLASSDLGEX",
    "CTL3DSUBCLASSCTL",
    "CTL3DUNREGISTER",
};

/*
 * 1010:00a2 — test whether the CTL3D file can be found in the exact original
 * search order. The 80-byte result is only a success indicator; LoadLibrary
 * later receives the unchanged global library name/path buffer.
 */
bool multimedia_locate_library(
    Win16FarPtr module, Win16FarPtr library_path)
{
    uint8_t search_path_bytes[256];
    uint8_t result_bytes[80];
    uint8_t extension_bytes[5];
    uint8_t file_name_bytes[9];
    Win16FarPtr search_path = win16_stack_pointer(search_path_bytes);
    Win16FarPtr result = win16_stack_pointer(result_bytes);
    Win16FarPtr extension = win16_stack_pointer(extension_bytes);
    Win16FarPtr file_name = win16_stack_pointer(file_name_bytes);

    win16_write_u8(search_path, 0);
    (void)multimedia_search_file(search_path, library_path, result);
    if (win16_read_u8(result) != 0) {
        return true;
    }

    (void)GetWindowsDirectoryFar16(search_path, 0xff);
    (void)multimedia_search_file(search_path, library_path, result);
    if (win16_read_u8(result) != 0) {
        return true;
    }

    (void)GetSystemDirectoryFar16(search_path, 0xff);
    (void)multimedia_search_file(search_path, library_path, result);
    if (win16_read_u8(result) != 0) {
        return true;
    }

    HINSTANCE16 module_handle = GetModuleHandle16(module);
    (void)GetModuleFileNameFar16(module_handle, search_path, 0x100);
    (void)multimedia_split_path(
        extension, file_name, search_path, search_path);
    (void)multimedia_search_file(search_path, library_path, result);
    if (win16_read_u8(result) != 0) {
        return true;
    }

    Win16FarPtr environment_path = multimedia_environment_value(
        win16_dgroup_pointer(0x046a));
    (void)multimedia_search_file(environment_path, library_path, result);
    return win16_read_u8(result) != 0;
}

/* 1010:0002 — unload the helper and clear every dynamically resolved slot. */
void multimedia_unload(void)
{
    if (g_multimedia_module >= 0x20) {
        (void)FreeLibrary16(g_multimedia_module);
    }
    g_multimedia_initialized = 0;
    for (unsigned index = 0; index < 11; index++) {
        g_multimedia_procedures[index] = 0;
    }
}

/* 1010:0079 — notify the helper for this task, then perform common unload. */
void multimedia_finalize_current_task(void)
{
    Win16FarPtr terminate_task = g_multimedia_procedures[10];
    if (g_multimedia_initialized && terminate_task != 0) {
        (void)win16_call_pascal_u16(terminate_task, GetCurrentTask16());
        multimedia_unload();
    }
}

/*
 * 1010:03e0 — multimedia-aware TApplication destructor. Finalize the current
 * helper task before the application/root destructors and owned-allocation
 * cleanup. The hidden VMT zero passed to TApplication prevents double free.
 */
void multimedia_application_destruct(
    Win16FarPtr object, uint16_t vmt)
{
    multimedia_finalize_current_task();
    object_windows_application_destruct(object, 0);
    BorlandObjectCallFrame frame = {object, vmt};
    borland_finish_object_destructor(&frame, 0);
}

/*
 * 1010:03af — exported loader wrapper. Each byte argument occupies a 16-bit
 * Pascal stack slot; only AL is returned. The target always clears 1028:4783
 * after the underlying 1010:01c2 call, regardless of its result.
 */
uint8_t multimedia_initialize_export(
    uint8_t argument_1,
    uint8_t argument_2,
    uint8_t argument_3,
    uint16_t argument_4,
    uint16_t argument_5)
{
    uint8_t result = multimedia_initialize(
        argument_1, argument_2, argument_3, argument_4, argument_5);
    g_multimedia_pending = 0;
    return result;
}

/*
 * 1010:01c2 — load and validate CTL3D.DLL/CTL3DV2.DLL.
 * Procedure slots retain their exact binary order at 1028:4750..477b.
 */
uint8_t multimedia_initialize(
    uint8_t argument_1,
    uint8_t argument_2,
    uint8_t auto_subclass,
    uint16_t module_offset,
    uint16_t module_selector)
{
    if (g_multimedia_initialized) {
        return 1;
    }

    if (!g_multimedia_legacy_windows) {
        (void)SetErrorMode16(0x8000);
        g_multimedia_module = LoadLibrary16(g_multimedia_library_path);
        (void)SetErrorMode16(0);
    } else {
        bool located = multimedia_locate_library(
            win16_make_far_pointer(module_selector, module_offset),
            win16_dgroup_pointer(0x478d));
        g_multimedia_module = located
            ? LoadLibrary16(g_multimedia_library_path)
            : 0;
    }

    if (g_multimedia_module < 0x20) {
        return 0;
    }
    for (unsigned index = 0; index < 11; index++) {
        if (index == 8 && g_multimedia_legacy_windows) {
            g_multimedia_procedures[index] = 0;
        } else {
            g_multimedia_procedures[index] = GetProcAddress16(
                g_multimedia_module, multimedia_procedure_names[index]);
        }
    }

    g_multimedia_initialized = win16_call_pascal_u16(
        g_multimedia_procedures[6], GetCurrentTask16()) != 0;
    if (g_multimedia_initialized) {
        g_multimedia_version =
            win16_call_pascal_u16_no_args(g_multimedia_procedures[5]);
        bool enabled = win16_call_pascal_u16_no_args(
            g_multimedia_procedures[3]) != 0;
        g_multimedia_initialized = enabled && g_multimedia_version >= 9;
    }
    if (!g_multimedia_initialized) {
        multimedia_unload();
        return 0;
    }

    g_multimedia_argument_2 = argument_2;
    g_multimedia_argument_1 = argument_1;
    if (!g_multimedia_legacy_windows && auto_subclass != 0) {
        g_multimedia_auto_subclassed = win16_call_pascal_u16(
            g_multimedia_procedures[0], g_win16_instance) != 0;
    } else {
        g_multimedia_auto_subclassed = 0;
    }
    return 1;
}