#include <string.h>
#include <stdio.h>

#include "error.h"
#include "debug.h"
#include "vmstate.h"
#include "vmval.h"
#include "unit.h"

int debug_breakpoint(struct vm *vm) {
    struct vm_func_entry *func;
    struct vm_unit *unit;
    uint64_t w0;
    uint32_t opcode;
    char line[256];
    char *p;

    unit = vector_ref(&vm->units, vm->lp);
    func = vector_ref(&unit->functions, vm->fp);
    opcode = func->bytecode[vm->ip];

    fprintf(stderr, "%02zx:%02zx:%04zx: %08x\n", vm->lp, vm->fp, vm->ip, opcode);

    while (1) {
        fprintf(stderr, ">> ");
        if (!fgets(line, sizeof(line), stdin)) {
            return 0;
        }
        if ((p = strchr(line, '\n')) != NULL) {
            *p = 0;
        }

        if (!strcmp(line, "s")) {
            vm->flags |= VM_SINGLESTEP;
            return 0;
        } else if (!strcmp(line, "c")) {
            vm->flags &= ~VM_SINGLESTEP;
            return 0;
        } else if (!strcmp(line, "q")) {
            return -ERR_ERROR_EXIT;
        } else if (!strcmp(line, "regs")) {
            fprintf(stderr, "  lp = 0x%04zx, fp = 0x%04zx\n", vm->lp, vm->fp);
            fprintf(stderr, "  ip = 0x%04zx\n", vm->ip);
            fprintf(stderr, "  dsp = 0x%04zx\n", vm->data_stack.sp);
            fprintf(stderr, "  csp = 0x%04zx, cbp = 0x%04zx\n", vm->call_stack.sp, vm->bp);
        } else if (!strcmp(line, "locals")) {
            fprintf(stderr, "Local variables:\n");
            for (size_t i = 0; i < func->local_count; ++i) {
                w0 = vm->call_stack.data[vm->bp - i - 1];
                fprintf(stderr, "[bp - %zu]: ", i + 1);
                vm_print(stderr, w0);
                fprintf(stderr, "\n");
            }
            fprintf(stderr, "Arguments:\n");
            for (size_t i = 0; i < func->argc; ++i) {
                w0 = vm->call_stack.data[vm->bp + i];
                fprintf(stderr, "[bp + %zu]: ", i);
                vm_print(stderr, w0);
                fprintf(stderr, "\n");
            }
        } else if (!strcmp(line, "bt")) {
            fprintf(stderr, "Call frame trace:\n");
            size_t bp, lp, fp, ip, sp;
            size_t count;
            struct vm_func_entry *f;
            struct vm_unit *u;

            bp = vm->bp;
            lp = vm->lp;
            fp = vm->fp;
            ip = vm->ip;
            count = 0;
            while (1) {
                u = vector_ref(&vm->units, lp);
                f = vector_ref(&u->functions, fp);
                sp = bp + f->argc;
                fprintf(stderr, "%2zu: %02zx:%02zx:%04zx: %08x\n",
                        count, lp, fp, ip, f->bytecode[ip]);

                if (count == 5) {
                    break;
                }
                bp = vm->call_stack.data[sp + 3];
                lp = vm->call_stack.data[sp + 2];
                fp = vm->call_stack.data[sp + 1];
                ip = vm->call_stack.data[sp + 0];
                ++count;

                if (bp == 0) {
                    break;
                }
            }
        }
    }
}