#include "unity.h"
#include "celrs/crsf.h"
#include <string.h>

void setUp(void) {}
void tearDown(void) {}

/* CRC tests — CRC8/DVB-S2 (poly 0xD5) */
void test_crc_empty(void) {
    uint8_t data[1] = {0};
    TEST_ASSERT_EQUAL_UINT8(0x00, cel_crsf_crc(data, 0));
}

void test_crc_single_byte(void) {
    uint8_t data[1] = {0x01};
    uint8_t crc = cel_crsf_crc(data, 1);
    TEST_ASSERT_TRUE(crc != 0); /* non-trivial */
}

void test_crc_known_value(void) {
    /* Verify CRC is deterministic */
    uint8_t data[6] = {0x10, 0x80, 0x03, 0x02, 0x80, 0x01};
    uint8_t crc = cel_crsf_crc(data, 6);
    TEST_ASSERT_TRUE(crc != 0);
    uint8_t crc2 = cel_crsf_crc(data, 6);
    TEST_ASSERT_EQUAL_UINT8(crc, crc2);
}

/* TODO: rewrite parse/build tests for new ELRS frame format.
 * New format: [addr][length][type][payload...][crc]
 * Old tests below use legacy functions for backward compat. */

/* Frame parse tests (legacy format) */
void test_parse_legacy_invalid_header(void) {
    cel_crsf_frame_legacy frame;
    uint8_t buf[8] = {0x00, 0x10, 0x80, 0x03, 0x02, 0x80, 0x01, 0x00};
    TEST_ASSERT_EQUAL_INT(-1, cel_crsf_frame_parse_legacy(&frame, buf, 8));
}

void test_parse_legacy_too_short(void) {
    cel_crsf_frame_legacy frame;
    uint8_t buf[2] = {0xC8, 0x10};
    TEST_ASSERT_EQUAL_INT(-1, cel_crsf_frame_parse_legacy(&frame, buf, 2));
}

void test_parse_legacy_null_frame(void) {
    uint8_t buf[8] = {0xC8, 0x10, 0x80, 0x03, 0x02, 0x80, 0x01, 0x00};
    TEST_ASSERT_EQUAL_INT(-1, cel_crsf_frame_parse_legacy(NULL, buf, 8));
}

void test_parse_legacy_null_buf(void) {
    cel_crsf_frame_legacy frame;
    TEST_ASSERT_EQUAL_INT(-1, cel_crsf_frame_parse_legacy(&frame, NULL, 8));
}

/* Frame build tests (legacy format) */
void test_build_legacy_heartbeat(void) {
    uint8_t dst[256];
    uint8_t payload[2] = {0x80, 0x01};
    size_t len = cel_crsf_frame_build_legacy(dst, 0x00, 0x80, 0x03,
                                              payload, 2);

    TEST_ASSERT_GREATER_THAN(0, len);
    TEST_ASSERT_EQUAL_UINT8(CEL_CRSF_FRAME_HEADER, dst[0]);
    TEST_ASSERT_EQUAL_UINT8(0x00, dst[1]);  /* destination */
    TEST_ASSERT_EQUAL_UINT8(0x80, dst[2]);  /* source */
    TEST_ASSERT_EQUAL_UINT8(0x03, dst[3]);  /* type: heartbeat */
    TEST_ASSERT_EQUAL_UINT8(0x02, dst[4]);  /* size */
    TEST_ASSERT_EQUAL_UINT8(0x80, dst[5]);  /* payload[0] */
    TEST_ASSERT_EQUAL_UINT8(0x01, dst[6]);  /* payload[1] */
}

void test_build_legacy_roundtrip(void) {
    uint8_t dst[256];
    uint8_t payload[4] = {0xAA, 0xBB, 0xCC, 0xDD};
    size_t len = cel_crsf_frame_build_legacy(dst, 0x10, 0x80, 0x01,
                                              payload, 4);

    /* Parse the built frame back */
    cel_crsf_frame_legacy frame;
    TEST_ASSERT_EQUAL_INT(0, cel_crsf_frame_parse_legacy(&frame, dst, len));
    TEST_ASSERT_EQUAL_UINT8(0x10, frame.destination);
    TEST_ASSERT_EQUAL_UINT8(0x80, frame.source);
    TEST_ASSERT_EQUAL_UINT8(0x01, frame.type);
    TEST_ASSERT_EQUAL_UINT8(4, frame.size);
    TEST_ASSERT_EQUAL_UINT8(0xAA, frame.payload[0]);
    TEST_ASSERT_EQUAL_UINT8(0xDD, frame.payload[3]);
}

void test_build_legacy_null_dst(void) {
    uint8_t payload[2] = {0x01, 0x02};
    TEST_ASSERT_EQUAL_UINT(0, cel_crsf_frame_build_legacy(NULL, 0x00, 0x80,
                                                           0x03, payload, 2));
}

void test_build_legacy_null_payload(void) {
    uint8_t dst[256];
    size_t len = cel_crsf_frame_build_legacy(dst, 0x10, 0x80, 0x03, NULL, 0);
    TEST_ASSERT_GREATER_THAN(0, len);
    /* Should still have valid CRC for empty payload */
    cel_crsf_frame_legacy frame;
    TEST_ASSERT_EQUAL_INT(0, cel_crsf_frame_parse_legacy(&frame, dst, len));
}

int main(void) {
    UNITY_BEGIN();
    RUN_TEST(test_crc_empty);
    RUN_TEST(test_crc_single_byte);
    RUN_TEST(test_crc_known_value);
    RUN_TEST(test_parse_legacy_invalid_header);
    RUN_TEST(test_parse_legacy_too_short);
    RUN_TEST(test_parse_legacy_null_frame);
    RUN_TEST(test_parse_legacy_null_buf);
    RUN_TEST(test_build_legacy_heartbeat);
    RUN_TEST(test_build_legacy_roundtrip);
    RUN_TEST(test_build_legacy_null_dst);
    RUN_TEST(test_build_legacy_null_payload);
    return UNITY_END();
}