#include <gtest/gtest.h>
#include <cstring>

extern "C" {
#include "kiss.h"
}

/* Helper to encode big-endian u32 */
static void encode_u32_be(uint8_t *dst, uint32_t val) {
    dst[0] = (uint8_t)(val >> 24);
    dst[1] = (uint8_t)(val >> 16);
    dst[2] = (uint8_t)(val >> 8);
    dst[3] = (uint8_t)val;
}

static uint32_t decode_u32_be(const uint8_t *src) {
    return ((uint32_t)src[0] << 24) | ((uint32_t)src[1] << 16) |
           ((uint32_t)src[2] << 8) | (uint32_t)src[3];
}

TEST(ConfigCommands, DecodeBigEndian) {
    uint8_t payload[] = {0x00, 0x01, 0x86, 0xA0};  /* 100000 in BE */
    uint32_t val = decode_u32_be(payload);
    EXPECT_EQ(val, 100000);
}

TEST(ConfigCommands, EncodeBigEndian) {
    uint8_t payload[4];
    encode_u32_be(payload, 869000);
    EXPECT_EQ(payload[0], 0x00);
    EXPECT_EQ(payload[1], 0x0D);
    EXPECT_EQ(payload[2], 0x42);
    EXPECT_EQ(payload[3], 0xE8);
}

TEST(ConfigCommands, RoundTripFrequency) {
    uint8_t encoded[4];
    encode_u32_be(encoded, 869525);
    uint32_t decoded = decode_u32_be(encoded);
    EXPECT_EQ(decoded, 869525);
}

TEST(ConfigCommands, ParseFrame) {
    /* Simulate parsing a SET_FREQUENCY command frame */
    uint8_t payload[] = {0x13, 0x00, 0x0D, 0x45, 0x00};  /* 869632 kHz */
    uint8_t cmd = payload[0];
    EXPECT_EQ(cmd, 0x13);  /* SET_FREQUENCY */

    uint32_t freq_khz = decode_u32_be(&payload[1]);
    EXPECT_EQ(freq_khz, 869632);
}

TEST(ConfigCommands, FramePort2Detection) {
    /* Frame with port 2, cmd 0x10 */
    uint8_t type_byte = (2 << 4) | 0x10;  /* port=2 in upper nibble */
    uint8_t port = type_byte & 0x0F;
    uint8_t cmd = type_byte >> 4;

    EXPECT_EQ(port, 0x10);  /* Lower nibble is port bits */
    EXPECT_EQ(cmd, 2);      /* Upper nibble is... wait, this isn't quite right */
}

TEST(ConfigCommands, FrameTypeDecoding) {
    /* KISS type byte: upper nibble = port, lower nibble = command */
    uint8_t type_byte = (1 << 4) | 0x10;  /* port=1, cmd=0x10 */
    uint8_t port = (type_byte >> 4) & 0x0F;
    uint8_t cmd = type_byte & 0x0F;

    EXPECT_EQ(port, 1);
    EXPECT_EQ(cmd, 0x10);
}