/* AVM ISA v1 — C Test Harness */
#include <stdio.h>
#include <assert.h>
#include <string.h>
#include "avm.c"

void test_basic_add() {
    Instr prog[] = {
        {OP_PUSH_Q16, 5 * Q16_SCALE, 0},
        {OP_PUSH_Q16, 3 * Q16_SCALE, 0},
        {OP_PRIM, PRIM_ADD_Q16, 0},
        {OP_HALT, 0, 0},
    };
    State s; init_state(&s, 0);
    int err = run(&s, prog, 4, 100);
    assert(err == 0);
    assert(s.halted);
    assert(s.stack[0].val.i == 8 * Q16_SCALE);
    printf("  ✅ basic_add: 5 + 3 = 8\n");
}

void test_div_q16() {
    Instr prog[] = {
        {OP_PUSH_Q16, 3 * Q16_SCALE, 0},
        {OP_PUSH_Q16, 5 * Q16_SCALE, 0},
        {OP_PRIM, PRIM_DIV_Q16, 0},
        {OP_HALT, 0, 0},
    };
    State s; init_state(&s, 0);
    int err = run(&s, prog, 4, 100);
    assert(err == 0);
    int expected = (3 * Q16_SCALE) / 5;
    assert(s.stack[0].val.i == expected);
    printf("  ✅ div_q16: 3/5 = 0.6\n");
}

void test_saturation() {
    Instr prog[] = {
        {OP_PUSH_Q16, AVM_CLAMP_MAX - 1, 0},
        {OP_PUSH_Q16, 2, 0},
        {OP_PRIM, PRIM_ADD_Q16, 0},
        {OP_HALT, 0, 0},
    };
    State s; init_state(&s, 0);
    int err = run(&s, prog, 4, 100);
    assert(err == 0);
    assert(s.stack[0].val.i == AVM_CLAMP_MAX);
    printf("  ✅ saturation: max-1+2 = max\n");
}

void test_v6_lt() {
    struct { int a, b; int exp; } cases[] = {
        {-5*Q16_SCALE, -3*Q16_SCALE, 1},
        {-3*Q16_SCALE, -5*Q16_SCALE, 0},
        {5*Q16_SCALE, 3*Q16_SCALE, 0},
        {3*Q16_SCALE, 5*Q16_SCALE, 1},
        {-1*Q16_SCALE, 2*Q16_SCALE, 1},
    };
    for (int i = 0; i < 5; i++) {
        Instr prog[] = {
            {OP_PUSH_Q16, cases[i].a, 0},
            {OP_PUSH_Q16, cases[i].b, 0},
            {OP_PRIM, PRIM_LT_Q16, 0},
            {OP_HALT, 0, 0},
        };
        State s; init_state(&s, 0);
        run(&s, prog, 4, 100);
        assert(s.stack[0].val.b == cases[i].exp);
    }
    printf("  ✅ v6_lt: 5 cases pass\n");
}

void test_type_mismatch() {
    Instr prog[] = {
        {OP_PUSH_BOOL, 0, 1},
        {OP_PUSH_Q16, Q16_SCALE, 0},
        {OP_PRIM, PRIM_ADD_Q16, 0},
    };
    State s; init_state(&s, 0);
    // C port returns default value on type mismatch (no error code)
    // Verify the result type is not Q16 (indicates silent failure)
    int err = run(&s, prog, 3, 100);
    assert(err == 0);
    assert(s.stack[s.sp].ty != TY_Q16 || s.stack[s.sp].val.i == 0);
    printf("  ✅ type_mismatch: handled (default value)\n");
}

void test_div_by_zero() {
    Instr prog[] = {
        {OP_PUSH_Q16, Q16_SCALE, 0},
        {OP_PUSH_Q16, 0, 0},
        {OP_PRIM, PRIM_DIV_Q16, 0},
    };
    State s; init_state(&s, 0);
    int err = run(&s, prog, 3, 100);
    assert(err != 0);
    printf("  ✅ div_by_zero: rejected\n");
}

void test_stack_overflow() {
    Instr prog[AVM_MAX_STACK + 2];
    for (int i = 0; i < AVM_MAX_STACK + 1; i++)
        prog[i] = (Instr){OP_PUSH_Q16, 0, 0};
    prog[AVM_MAX_STACK + 1] = (Instr){OP_HALT, 0, 0};
    State s; init_state(&s, 0);
    int err = run(&s, prog, AVM_MAX_STACK + 2, 100);
    assert(err != 0);
    printf("  ✅ stack_overflow: rejected\n");
}

void test_control_flow() {
    Instr prog[] = {
        {OP_PUSH_BOOL, 0, 1},
        {OP_JUMP_IF, 4, 0},
        {OP_PUSH_Q16, 0, 0},
        {OP_HALT, 0, 0},
        {OP_PUSH_Q16, Q16_SCALE, 0},
        {OP_HALT, 0, 0},
    };
    State s; init_state(&s, 0);
    int err = run(&s, prog, 6, 100);
    assert(err == 0);
    assert(s.stack[0].val.i == Q16_SCALE);
    printf("  ✅ control_flow: jump_if true\n");
}

void test_locals() {
    Instr prog[] = {
        {OP_PUSH_Q16, 42 * Q16_SCALE, 0},
        {OP_STORE, 0, 0},
        {OP_LOAD, 0, 0},
        {OP_HALT, 0, 0},
    };
    State s; init_state(&s, 1);
    int err = run(&s, prog, 4, 100);
    assert(err == 0);
    assert(s.stack[0].val.i == 42 * Q16_SCALE);
    printf("  ✅ locals: store+load\n");
}

int main() {
    printf("AVM C Port — Test Harness\n");
    printf("=========================\n");
    test_basic_add();
    test_div_q16();
    test_saturation();
    test_v6_lt();
    test_type_mismatch();
    test_div_by_zero();
    test_stack_overflow();
    test_control_flow();
    test_locals();
    printf("\nAll C tests passed.\n");
    return 0;
}