#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <emscripten/emscripten.h>
#include <vb.h>



/////////////////////////////// Module Commands ///////////////////////////////

// Allocate and initialize multiple simulations
EMSCRIPTEN_KEEPALIVE VB** Create(int count) {
    VB **sims = malloc(count * sizeof (void *));
    for (int x = 0; x < count; x++)
        vbReset(sims[x] = malloc(sizeof (VB)));
    return sims;
}

// Delete a simulation
EMSCRIPTEN_KEEPALIVE void Destroy(VB *sim) {
    free(&sim->cart.rom);
    free(&sim->cart.sram);
    free(sim);
}

// Proxy for free()
EMSCRIPTEN_KEEPALIVE void Free(void *ptr) {
    free(ptr);
}

// Proxy for malloc()
EMSCRIPTEN_KEEPALIVE void* Malloc(int size) {
    return malloc(size);
}

// Determine the size in bytes of a pointer
EMSCRIPTEN_KEEPALIVE int PointerSize() {
    return sizeof (void *);
}

// Read multiple bytes from the bus
EMSCRIPTEN_KEEPALIVE void ReadBuffer(
    VB* sim, uint8_t *dest, uint32_t address, uint32_t size) {
    for (; size > 0; address++, size--, dest++)
        *dest = vbRead(sim, address, VB_U8, 1);
}

// Supply a ROM buffer
EMSCRIPTEN_KEEPALIVE int SetROM(VB *sim, uint8_t *rom, uint32_t size) {
    uint8_t *prev = vbGetROM(sim, NULL);
    int      ret  = vbSetROM(sim, rom, size);
    if (ret) {
        free(prev);
        vbReset(sim);
    }
    return ret;
}

// Write multiple bytes to the bus
EMSCRIPTEN_KEEPALIVE void WriteBuffer(
    VB* sim, uint8_t *src, uint32_t address, uint32_t size) {
    for (; size > 0; address++, size--, src++)
        vbWrite(sim, address, VB_U8, *src, 1);
}



////////////////////////////// Debugger Commands //////////////////////////////

// Attempt to execute until the following instruction
static uint32_t RunNextPC;
static int RunNextProcB(VB *sim, int fetch, VB_ACCESS *acc) {
    if (fetch == 0 && vbGetProgramCounter(sim) == RunNextPC)
        return 1;
    acc->value = vbRead(sim, acc->address, acc->type, 0);
    return 0;
}
static int RunNextProcA(VB *sim, VB_INSTRUCTION *inst) {
    RunNextPC = vbGetProgramCounter(sim) + inst->size;
    vbSetCallback(sim, VB_ONEXECUTE, NULL);
    vbSetCallback(sim, VB_ONFETCH, &RunNextProcB);
    return 0;
}
EMSCRIPTEN_KEEPALIVE void RunNext(VB *sim0, VB *sim1) {
    uint32_t clocks = 400000; // 1/50s
    VB      *sims[2];

    vbSetCallback(sim0, VB_ONEXECUTE, &RunNextProcA);

    if (sim1 != NULL) {
        sims[0] = sim0;
        sims[1] = sim1;
        vbEmulateMulti(sims, 2, &clocks);
    }

    else vbEmulate(sim0, &clocks);

    vbSetCallback(sim0, VB_ONFETCH, NULL);
}

// Execute one instruction
static uint32_t SingleStepPC;
static int SingleStepProc(VB *sim, int fetch, VB_ACCESS *acc) {
    if (fetch == 0 && vbGetProgramCounter(sim) != SingleStepPC)
        return 1;
    acc->value = vbRead(sim, acc->address, acc->type, 0);
    return 0;
}
EMSCRIPTEN_KEEPALIVE void SingleStep(VB *sim0, VB *sim1) {
    uint32_t clocks = 400000; // 1/50s
    VB      *sims[2];

    SingleStepPC = vbGetProgramCounter(sim0);
    vbSetCallback(sim0, VB_ONFETCH, &SingleStepProc);

    if (sim1 != NULL) {
        sims[0] = sim0;
        sims[1] = sim1;
        vbEmulateMulti(sims, 2, &clocks);
    }

    else vbEmulate(sim0, &clocks);

    vbSetCallback(sim0, VB_ONFETCH, NULL);
}

EMSCRIPTEN_KEEPALIVE uint32_t Clocks(VB *sim) {
    return sim->cpu.clocks;
}