#define MCAP_IMPLEMENTATION
#include <mcap/reader.hpp>

#include <foxglove/CompressedVideo.pb.h>

#include <CLI/CLI.hpp>

#include <cstdint>
#include <expected>
#include <fstream>
#include <iostream>
#include <optional>
#include <string>

#include <spdlog/spdlog.h>

namespace {

enum class TesterExitCode : int {
	Success = 0,
	OpenError = 2,
	SchemaError = 3,
	TopicMismatch = 4,
	TimestampError = 5,
	ParseError = 6,
	FormatMismatch = 7,
	EmptyPayload = 8,
	ThresholdError = 9,
	DumpError = 10,
};

[[nodiscard]]
constexpr int exit_code(TesterExitCode code) {
	return static_cast<int>(code);
}

struct Config {
	std::string input_path{};
	std::optional<std::string> expected_topic{};
	std::optional<std::string> expected_format{};
	std::optional<std::string> dump_annexb_output{};
	std::uint32_t min_messages{1};
};

[[nodiscard]]
std::expected<Config, int> parse_args(int argc, char **argv) {
	Config config{};
	CLI::App app{"mcap_reader_tester - validate foxglove.CompressedVideo MCAP output"};
	app.add_option("input", config.input_path, "Input MCAP path")->required();
	app.add_option("--expect-topic", config.expected_topic, "Expected MCAP topic");
	app.add_option("--expect-format", config.expected_format, "Expected CompressedVideo format");
	app.add_option("--dump-annexb-output", config.dump_annexb_output, "Write concatenated CompressedVideo.data payloads to a file");
	app.add_option("--min-messages", config.min_messages, "Minimum expected message count")->check(CLI::PositiveNumber);

	try {
		app.parse(argc, argv);
	} catch (const CLI::ParseError &e) {
		return std::unexpected(app.exit(e));
	}
	return config;
}

}

int main(int argc, char **argv) {
	auto config = parse_args(argc, argv);
	if (!config) {
		return config.error();
	}

	mcap::McapReader reader{};
	const auto open_status = reader.open(config->input_path);
	if (!open_status.ok()) {
		spdlog::error("failed to open MCAP file '{}': {}", config->input_path, open_status.message);
		return exit_code(TesterExitCode::OpenError);
	}

	std::uint64_t message_count{0};
	std::uint64_t previous_log_time{0};
	bool saw_log_time{false};
	std::optional<std::ofstream> dump_stream{};
	if (config->dump_annexb_output) {
		dump_stream.emplace(*config->dump_annexb_output, std::ios::binary | std::ios::trunc);
		if (!dump_stream->is_open()) {
			spdlog::error("failed to open dump output '{}'", *config->dump_annexb_output);
			reader.close();
			return exit_code(TesterExitCode::DumpError);
		}
	}

	auto message_view = reader.readMessages();
	for (auto it = message_view.begin(); it != message_view.end(); ++it) {
		if (it->schema == nullptr || it->channel == nullptr) {
			spdlog::error("MCAP message missing schema or channel metadata");
			reader.close();
			return exit_code(TesterExitCode::SchemaError);
		}
		if (it->schema->encoding != "protobuf" || it->schema->name != "foxglove.CompressedVideo") {
			continue;
		}
		if (it->channel->messageEncoding != "protobuf") {
			spdlog::error("unexpected MCAP message encoding: {}", it->channel->messageEncoding);
			reader.close();
			return exit_code(TesterExitCode::SchemaError);
		}
		if (config->expected_topic && it->channel->topic != *config->expected_topic) {
			spdlog::error("unexpected topic: expected '{}' got '{}'", *config->expected_topic, it->channel->topic);
			reader.close();
			return exit_code(TesterExitCode::TopicMismatch);
		}
		if (saw_log_time && it->message.logTime < previous_log_time) {
			spdlog::error("non-monotonic logTime detected: {} < {}", it->message.logTime, previous_log_time);
			reader.close();
			return exit_code(TesterExitCode::TimestampError);
		}

		foxglove::CompressedVideo message{};
		if (!message.ParseFromArray(it->message.data, static_cast<int>(it->message.dataSize))) {
			spdlog::error("failed to parse foxglove.CompressedVideo payload");
			reader.close();
			return exit_code(TesterExitCode::ParseError);
		}
		if (config->expected_format && message.format() != *config->expected_format) {
			spdlog::error("unexpected format: expected '{}' got '{}'", *config->expected_format, message.format());
			reader.close();
			return exit_code(TesterExitCode::FormatMismatch);
		}
		if (message.data().empty()) {
			spdlog::error("compressed video payload is empty");
			reader.close();
			return exit_code(TesterExitCode::EmptyPayload);
		}
		if (dump_stream) {
			dump_stream->write(message.data().data(), static_cast<std::streamsize>(message.data().size()));
			if (!dump_stream->good()) {
				spdlog::error("failed to write Annex B dump to '{}'", *config->dump_annexb_output);
				reader.close();
				return exit_code(TesterExitCode::DumpError);
			}
		}

		previous_log_time = it->message.logTime;
		saw_log_time      = true;
		message_count += 1;
	}

	reader.close();

	if (message_count < config->min_messages) {
		spdlog::error("message threshold not met: {} < {}", message_count, config->min_messages);
		return exit_code(TesterExitCode::ThresholdError);
	}

	spdlog::info("validated {} foxglove.CompressedVideo MCAP messages", message_count);
	return exit_code(TesterExitCode::Success);
}