/*
  StarForth — Steady-State Virtual Machine Runtime

  Copyright (c) 2023–2025 Robert A. James
  All rights reserved.

  Licensed under the StarForth License, Version 1.0
*/

/* keyboard_words.c — raw scancode-ring diagnostic word (FABRIC.md item
 * 4.3.5). Kernel-only, amd64-only; no-op elsewhere. */

#include "include/keyboard_words.h"
#include "../../include/word_registry.h"

#if defined(__STARKERNEL__) && defined(ARCH_AMD64)
#include "starkernel/i8042.h"
#endif

#if defined(__STARKERNEL__) && (defined(ARCH_RISCV64) || defined(ARCH_AARCH64))
#include "starkernel/virtio_input.h"
#endif

#if defined(__STARKERNEL__)
#include "starkernel/console.h"
#endif

/* KBD-SCAN ( -- c -1 | 0 ) */
static void kbw_scan(VM *vm)
{
#if defined(__STARKERNEL__) && defined(ARCH_AMD64)
    uint8_t sc;
    if (i8042_pop_scancode(&sc)) {
        vm_push(vm, (cell_t)sc);
        vm_push(vm, -1);
    } else {
        vm_push(vm, 0);
    }
#else
    vm_push(vm, 0);
#endif
}

/* KBD-DEBUG ( -- isr_count spurious_count ): cheap standing diagnostic,
 * not scaffolding -- confirms the interrupt path is alive (isr_count) and
 * flags the failure mode item 4.3.5 found (a real IRQ misreported as
 * spurious) without needing a live debugger. */
extern volatile uint32_t g_i8042_isr_count;
extern volatile uint32_t g_spurious_count;
static void kbw_debug(VM *vm)
{
#if defined(__STARKERNEL__) && defined(ARCH_AMD64)
    vm_push(vm, (cell_t)g_i8042_isr_count);
    vm_push(vm, (cell_t)g_spurious_count);
#else
    vm_push(vm, 0);
    vm_push(vm, 0);
#endif
}

/* VKBD-EVENT ( -- code value -1 | 0 ): item 4.3.5c (riscv64) / 4.3.5e
 * (aarch64) virtio-input. Pop one decoded EV_KEY event off the
 * interrupt-fed ring buffer. Pushes code and value and -1 (true) if one
 * was available, or just 0 (false) if the buffer was empty. Distinct word
 * from KBD-SCAN rather than a shared one: different device, different
 * event shape (Linux-style code/value pair vs. a raw XT scancode byte) --
 * convergence onto one interface is item 4.3.5f's explicit job, not this
 * one's. */
static void kbw_vevent(VM *vm)
{
#if defined(__STARKERNEL__) && (defined(ARCH_RISCV64) || defined(ARCH_AARCH64))
    uint16_t code;
    uint32_t value;
    if (virtio_input_pop_event(&code, &value)) {
        vm_push(vm, (cell_t)code);
        vm_push(vm, (cell_t)value);
        vm_push(vm, -1);
    } else {
        vm_push(vm, 0);
    }
#else
    vm_push(vm, 0);
#endif
}

/* VKBD-DEBUG ( -- isr_count ): standing diagnostic, same shape as
 * KBD-DEBUG -- confirms the virtio-input interrupt path is alive. */
extern volatile uint32_t g_virtio_input_isr_count;
static void kbw_vdebug(VM *vm)
{
#if defined(__STARKERNEL__) && (defined(ARCH_RISCV64) || defined(ARCH_AARCH64))
    vm_push(vm, (cell_t)g_virtio_input_isr_count);
#else
    vm_push(vm, 0);
#endif
}

/* KEY-EVENT ( -- keycode pressed -1 | 0 ): item 4.3.5f convergence
 * checkpoint. One shared shape across all three architectures instead of
 * KBD-SCAN's raw XT scancode byte or VKBD-EVENT's Linux code/value pair.
 * keycode is the Linux input keycode namespace (linux/input-event-codes.h);
 * pressed is 1 (press) or 0 (release).
 *
 * amd64 needs a real translation, not an invented one: XT Set-1's make
 * code for a key and Linux's keycode for that same key are the *same
 * number*, confirmed against this build host's own
 * /usr/include/linux/input-event-codes.h and against this tree's own
 * live-observed values (item 4.3.5's done note: 'a' -> 30, 'b' -> 48,
 * matching KEY_A=30/KEY_B=48 exactly) -- not a coincidence, a documented
 * historical property of how the Linux input keycode numbering was
 * originally defined around the AT/XT scancode set. Break codes set XT's
 * bit 7 (make|0x80) rather than carrying a separate press/release field,
 * so `keycode = sc & 0x7F, pressed = !(sc & 0x80)` is the whole
 * translation for the entire non-extended key range. Extended
 * (0xE0-prefixed) scancodes are not decoded here -- this checkpoint needs
 * one shared shape proven live per architecture, not full keyboard
 * coverage; that belongs to the REPL wiring item (M8) this checkpoint
 * unblocks.
 *
 * riscv64/aarch64 need no translation at all -- virtio-input's `code`
 * field already lives in the same Linux keycode namespace; `value` is
 * mapped 1:1 except autorepeat (value=2), folded into "still pressed"
 * here since this checkpoint's shape only distinguishes press/release. */
/* FABRIC.md item 4.4v: shared C-level implementation, so the REPL
 * keyboard bridge (repl.c) and the KEY-EVENT FORTH word below poll the
 * exact same converged event stream rather than each re-deriving the
 * per-arch translation kbw_key_event's own doc comment already explains
 * (XT Set-1 make code == Linux keycode for the non-extended range; break
 * codes set bit 7 instead of carrying a separate field). */
int sk_key_event_poll(uint16_t *keycode, int *pressed)
{
#if defined(__STARKERNEL__) && defined(ARCH_AMD64)
    uint8_t sc;
    if (i8042_pop_scancode(&sc)) {
        *keycode = (uint16_t)(sc & 0x7Fu);
        *pressed = (sc & 0x80u) ? 0 : 1;
        return 1;
    }
    return 0;
#elif defined(__STARKERNEL__) && (defined(ARCH_RISCV64) || defined(ARCH_AARCH64))
    uint16_t code;
    uint32_t value;
    if (virtio_input_pop_event(&code, &value)) {
        *keycode = code;
        *pressed = (value == 0u) ? 0 : 1;
        return 1;
    }
    return 0;
#else
    (void)keycode; (void)pressed;
    return 0;
#endif
}

static void kbw_key_event(VM *vm)
{
    uint16_t keycode;
    int pressed;

    if (sk_key_event_poll(&keycode, &pressed)) {
        vm_push(vm, (cell_t)keycode);
        vm_push(vm, (cell_t)pressed);
        vm_push(vm, -1);
    } else {
        vm_push(vm, 0);
    }
}

/* ALT+TAB ( -- ): FABRIC.md item 4.4y-revised. Programmatic equivalent of
 * the physical Alt+TAB interception (repl.c's sk_kbd_getc()) -- both call
 * console_fb_toggle_graphics(), so there is exactly one state-machine
 * transition, invoked two ways. */
static void kbw_alt_tab(VM *vm)
{
    (void)vm;
#if defined(__STARKERNEL__)
    console_fb_toggle_graphics();
#endif
}

void register_keyboard_words(VM *vm)
{
    register_word(vm, "KBD-SCAN", kbw_scan);
    register_word(vm, "KBD-DEBUG", kbw_debug);
    register_word(vm, "VKBD-EVENT", kbw_vevent);
    register_word(vm, "VKBD-DEBUG", kbw_vdebug);
    register_word(vm, "KEY-EVENT", kbw_key_event);
    register_word(vm, "ALT+TAB", kbw_alt_tab);
}