#include "exec.h"
#include "bytecode.h"

void exec_init(exec_t* self)
{
    assert(self);
    self->pc = 0;
    err_init(&self->err);
}

void exec_free(exec_t* self)
{
    assert(self);
    err_free(&self->err);
}

void exec_module(exec_t* self, module_t* module)
{
    assert(self);
    assert(module);

    self->pc = 0;

    while (self->pc < module->prog.instrs.size)
    {
        if (!err_is_ok(&self->err))
        {
            return;
        }

        instr_t const* instr = module->prog.instrs.data[self->pc];
        exec_instr(self, module, instr->opcode, instr->param);
    }
}

void exec_instr(exec_t* self,
                module_t* module,
                Opcode op,
                int param)
{
    assert(self);

    ccm_t* ccm = &module->ccm;

    switch (op)
    {
        case OP_INDEX: {
            CCM ccm_target = ccm_pop(ccm);
            vec_t* target = ccm_from_tuple(ccm, ccm_target);
            value_t* result = NULL;

            for (int i=0; i<param; i++)
            {
                CCM ccm_idx = ccm_pop(ccm);
                int idx = ccm_from_num(ccm, ccm_idx);

                if (idx < 0)
                {
                    idx = target->size + idx;
                }

                if (idx < 0 || idx >= (ssize_t) target->size)
                {
                    assert(target->size > 0);
                    err_push(&self->err, ((value_t*)target->data[0])->line,
                             "index out of bounds");
                    return;
                }

                value_t* val = target->data[idx];

                if (i == param - 1)
                {
                    result = val;
                }
                else
                {
                    target = val->data.tuple;
                }
            }

            ccm_push(ccm, ccm_from_value(ccm, result));
            self->pc++;
        } break;

        case OP_NOT: {
            ccm_not(ccm);
            self->pc++;
        } break;

        case OP_IN: {
            ccm_in(ccm);
            self->pc++;
        } break;

        case OP_BR: {
            self->pc = param;
        } break;

        case OP_BRF: {
            CCM value = ccm_pop(ccm);
            int val = ccm_from_boolean(ccm, value);

            if (val)
            {
                self->pc++;
            }
            else
            {
                self->pc = param;
            }
        } break;

        case OP_ASSERT_NE:
        case OP_ASSERT_EQ: {
            CCM val = ccm_pop(ccm);
            vec_t* values = ccm_from_tuple(ccm, val);
            assert(values->size == 2);
            int oracle = 1;

            if (op == OP_ASSERT_NE)
            {
                oracle = 0;
            }

            if (value_equals(values->data[0],
                              values->data[1]) == !oracle)
            {
                char lhs[CCM_STRLEN];
                value_str(values->data[0], lhs, CCM_STRLEN);

                char rhs[CCM_STRLEN];
                value_str(values->data[1], rhs, CCM_STRLEN);
                char const* operator = oracle ? "==" : "!=";

                err_push(
                    &self->err,
                    ((value_t*) values->data[0])->line,
                    "assertion failed: <%s> %s <%s>",
                    lhs, operator, rhs
                );
            }

            self->pc++;

        } break;

        case OP_PUSH: {
            CCM value = (CCM) module->prog.constants.data[param];
            ccm_push(ccm, value);
            self->pc++;
        } break;

        case OP_POP: {
            ccm_pop(ccm);
            self->pc++;
        } break;

        case OP_ADD: { ccm_add(ccm); self->pc++; } break;
        case OP_SUB: { ccm_sub(ccm); self->pc++; } break;
        case OP_USUB: { ccm_usub(ccm); self->pc++; } break;
        case OP_MUL: { ccm_mul(ccm); self->pc++; } break;
        case OP_DIV: { ccm_div(ccm); self->pc++; } break;
        case OP_MOD: { ccm_mod(ccm); self->pc++; } break;
        case OP_POW: { ccm_pow(ccm); self->pc++; } break;

        case OP_MK_TUPLE: {
            vec_t* values = malloc(sizeof(vec_t));
            vec_init(values);
            int line = -1;

            for (int i=0; i<param; i++)
            {
                CCM val = ccm_pop(ccm);
                value_t* v = value_new_clone(ccm->values.data[val]);
                vec_push(values, v);

                if (line == -1)
                {
                    line = v->line;
                }
            }

            CCM value = ccm_to_tuple(ccm, values, line);
            ccm_push(ccm, value);

            self->pc++;
        } break;

        default: {
            fprintf(stderr,
                    "cannot exec opcode '%s'",
                    OpcodeStr[op]);
            abort();
        }
    }
}