#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "dcpu16.h"
#include "hw_keyboard.h"

#define BUF_SZ 32

static dcpu16_hw_signal_t keyboard_reset_;
static dcpu16_hw_signal_t keyboard_cycle_;
static dcpu16_hw_signal_t keyboard_hwi_;
static struct dcpu16_hw hw_ = {
    .name_  = "Generic Keyboard (compatible)",
    .id_l   = 0x7406,
    .id_h   = 0x30cf,
    .ver    = 0x0001,
    .mfg_l  = 0x0000,
    .mfg_h  = 0x0000,
    .hwi    = keyboard_hwi_,
    .cycle  = keyboard_cycle_,
    .reset  = keyboard_reset_,
    .data   = (struct keyboard_ *)NULL
};

struct keyboard_ {
    char *buf;
    size_t buf_sz;
    DCPU16_WORD interrupt_message;
};

static
void keyboard_reset_(struct dcpu16 *vm, void *data) {
    struct keyboard_ *keyboard = (struct keyboard_ *)data;

    (void)vm;

    keyboard->interrupt_message = 0;
    memset(keyboard->buf, 0, keyboard->buf_sz);
}

static
void keyboard_cycle_(struct dcpu16 *vm, void *data) {
    struct keyboard_ *keyboard = (struct keyboard_ *)data;

    (void)vm, (void)keyboard;
}

static
void keyboard_hwi_(struct dcpu16 *vm, void *data) {
    struct keyboard_ *keyboard = (struct keyboard_ *)data;
    DCPU16_WORD reg_a = vm->reg[DCPU16_REG_A];
    DCPU16_WORD reg_b = vm->reg[DCPU16_REG_B];
    size_t i;

    switch (reg_a) {
        case 0: /* clear keyboard buffer */
            memset(keyboard->buf, 0, keyboard->buf_sz);
            break;

        case 1: /* get next key from buffer as C */
            vm->reg[DCPU16_REG_C] = keyboard->buf[0];
            for (i = 1; i < keyboard->buf_sz; i++) {
                keyboard->buf[i-1] = keyboard->buf[i];
            }
            keyboard->buf[i] = '\0';
            break;

        case 2: /* get currently-pressed-state of key in B as C */
            vm->warn_cb_("IMPLEMENT");
            (void)reg_b;
            vm->reg[DCPU16_REG_C] = 0;
            break;

        case 3: /* set interrupt state */
            keyboard->interrupt_message = reg_b;
            break;

    }
}

struct dcpu16_hw *keyboard_new(struct dcpu16 *vm) {
    struct dcpu16_hw *hw;
    char *b;

    hw = calloc(1, sizeof *hw);
    if (hw == NULL) {
        vm->warn_cb_("%s():%s", "calloc", strerror(errno));
        return NULL;
    }
    memcpy(hw, &hw_, sizeof *hw);
    hw->data = calloc(1, sizeof hw->data);
    if (hw->data == NULL) {
        vm->warn_cb_("%s():%s", "calloc", strerror(errno));
        free(hw);
        return NULL;
    }

    b = calloc(BUF_SZ, sizeof *b);
    if (b == NULL) {
        vm->warn_cb_("%s():%s", "calloc", strerror(errno));
        free(hw->data);
        free(hw);
        return NULL;
    }
    ((struct keyboard_ *)(hw->data))->buf = b;
    ((struct keyboard_ *)(hw->data))->buf_sz = BUF_SZ;

    return hw;
}

void keyboard_del(struct dcpu16_hw **hw) {
    if (hw) {
        free(((struct keyboard_ *)((*hw)->data))->buf);
        ((struct keyboard_ *)((*hw)->data))->buf = NULL;

        free((*hw)->data);
        (*hw)->data = NULL;

        free(*hw);
        *hw = NULL;
    }
}