#include <doctest/doctest.h>

#include <vector>

#include "packeteer/net/lldp.hpp"

using namespace packeteer::net;

namespace {

std::vector<unsigned char> tlv(std::uint8_t type, const std::vector<unsigned char>& value) {
    std::uint16_t header = static_cast<std::uint16_t>((type << 9) | value.size());
    std::vector<unsigned char> out = {static_cast<unsigned char>(header >> 8),
                                       static_cast<unsigned char>(header & 0xFF)};
    out.insert(out.end(), value.begin(), value.end());
    return out;
}

std::vector<unsigned char> lldpdu(std::optional<std::vector<unsigned char>> extra_tlv = {}) {
    std::vector<unsigned char> bytes;
    auto chassis_id = tlv(1, {4, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF});  // subtype 4: MAC
    auto port_id = tlv(2, {7, 'e', 't', 'h', '0'});                     // subtype 7: locally assigned
    auto ttl = tlv(3, {0x00, 0x78});                                    // 120 seconds
    bytes.insert(bytes.end(), chassis_id.begin(), chassis_id.end());
    bytes.insert(bytes.end(), port_id.begin(), port_id.end());
    bytes.insert(bytes.end(), ttl.begin(), ttl.end());
    if (extra_tlv) bytes.insert(bytes.end(), extra_tlv->begin(), extra_tlv->end());
    auto end = tlv(0, {});
    bytes.insert(bytes.end(), end.begin(), end.end());
    return bytes;
}

}  // namespace

TEST_CASE("parse_lldp decodes the three mandatory TLVs") {
    auto msg = parse_lldp(lldpdu());
    REQUIRE(msg.has_value());
    REQUIRE(msg->chassis_id.has_value());
    CHECK(*msg->chassis_id == "aa:bb:cc:dd:ee:ff");
    REQUIRE(msg->port_id.has_value());
    CHECK(*msg->port_id == "eth0");
    REQUIRE(msg->ttl.has_value());
    CHECK(*msg->ttl == 120);
    CHECK_FALSE(msg->system_name.has_value());
}

TEST_CASE("parse_lldp decodes the System Name TLV when present") {
    auto msg = parse_lldp(lldpdu(tlv(5, {'s', 'w', 'i', 't', 'c', 'h', '1'})));
    REQUIRE(msg.has_value());
    REQUIRE(msg->system_name.has_value());
    CHECK(*msg->system_name == "switch1");
}

TEST_CASE("parse_lldp skips over an unrecognized TLV without losing later ones") {
    // Type 6 (System Description) isn't decoded, but must not break
    // parsing of the End TLV that follows it.
    auto msg = parse_lldp(lldpdu(tlv(6, {'d', 'e', 's', 'c'})));
    REQUIRE(msg.has_value());
    REQUIRE(msg->chassis_id.has_value());
    REQUIRE(msg->port_id.has_value());
    REQUIRE(msg->ttl.has_value());
}

TEST_CASE("parse_lldp rejects a message missing a mandatory TLV") {
    // Chassis ID and Port ID only, no TTL - not a well-formed LLDPDU.
    std::vector<unsigned char> bytes;
    auto chassis_id = tlv(1, {4, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF});
    auto port_id = tlv(2, {7, 'e', 't', 'h', '0'});
    bytes.insert(bytes.end(), chassis_id.begin(), chassis_id.end());
    bytes.insert(bytes.end(), port_id.begin(), port_id.end());
    auto end = tlv(0, {});
    bytes.insert(bytes.end(), end.begin(), end.end());

    CHECK_FALSE(parse_lldp(bytes).has_value());
}

TEST_CASE("parse_lldp rejects an empty buffer") {
    std::vector<unsigned char> bytes;
    CHECK_FALSE(parse_lldp(bytes).has_value());
}

TEST_CASE("format_lldp_id renders a MAC-address subtype as hex-colon") {
    std::vector<unsigned char> mac = {0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF};
    CHECK(format_lldp_id(4, mac) == "aa:bb:cc:dd:ee:ff");
}

TEST_CASE("format_lldp_id renders a non-MAC subtype as plain text") {
    std::vector<unsigned char> text = {'e', 't', 'h', '0'};
    CHECK(format_lldp_id(7, text) == "eth0");
}

TEST_CASE("lldp_summary formats chassis/port/ttl, and name only when present") {
    LldpInfo info{"aa:bb:cc:dd:ee:ff", "eth0", 120, std::nullopt};
    CHECK(lldp_summary(info) == "LLDP chassis=aa:bb:cc:dd:ee:ff port=eth0 ttl=120");

    info.system_name = "switch1";
    CHECK(lldp_summary(info) == "LLDP chassis=aa:bb:cc:dd:ee:ff port=eth0 ttl=120 name=switch1");
}