/**
 * @file main.cc
 * @brief Parses command-line options, validates runtime mode selection,
 * initializes shared infrastructure, and executes the pipeline entry flow.
 */

#include <spdlog/spdlog.h>

#include <boost/di.hpp>
#include <boost/program_options.hpp>
#include <chrono>
#include <exception>
#include <memory>
#include <optional>
#include <sstream>
#include <string>

#include "biergarten_data_generator.h"
#include "data_generation/llama_generator.h"
#include "data_generation/mock_generator.h"
#include "data_generation/prompt_formatting/gemma4_jinja_prompt_formatter.h"
#include "data_model/application_options.h"
#include "llama_backend_state.h"
#include "services/enrichment_service.h"
#include "services/wikipedia_service.h"
#include "web_client/curl_web_client.h"

namespace prog_opts = boost::program_options;
namespace di = boost::di;

/**
 * @brief Parse command-line arguments into ApplicationOptions.
 *
 * @param argc Command-line argument count.
 * @param argv Command-line arguments.
 * @return Parsed ApplicationOptions if parsing succeeded, std::nullopt
 * otherwise.
 */
std::optional<ApplicationOptions> ParseArguments(const int argc, char** argv) {
  prog_opts::options_description desc("Pipeline Options");

  auto opt = desc.add_options();

  opt("help,h", "Produce help message");

  opt("mocked", prog_opts::bool_switch(),
      "Use mocked generator for brewery/user data");

  opt("model,m", prog_opts::value<std::string>()->default_value(""),
      "Path to LLM model (gguf)");

  opt("temperature", prog_opts::value<float>()->default_value(1.0F),
      "Sampling temperature (higher = more random)");

  opt("top-p", prog_opts::value<float>()->default_value(0.95F),
      "Nucleus sampling top-p in (0,1] (higher = more random)");

  opt("top-k", prog_opts::value<uint32_t>()->default_value(64),
      "Top-k sampling parameter (higher = more candidate tokens)");

  opt("n-ctx", prog_opts::value<uint32_t>()->default_value(8192),
      "Context window size in tokens (1-32768)");

  opt("seed", prog_opts::value<int>()->default_value(-1),
      "Sampler seed: -1 for random, otherwise non-negative integer");

  // Handle the "no arguments" or "help" case
  if (argc == 1) {
    spdlog::info("Biergarten Pipeline");
    std::stringstream usage_stream;
    usage_stream << "\nUsage: biergarten-pipeline [options]\n\n" << desc;
    spdlog::info(usage_stream.str());
    return std::nullopt;
  }

  try {
    prog_opts::variables_map variables_map;
    prog_opts::store(prog_opts::parse_command_line(argc, argv, desc),
                     variables_map);
    prog_opts::notify(variables_map);

    if (variables_map.contains("help")) {
      std::stringstream help_stream;
      help_stream << "\n" << desc;
      spdlog::info(help_stream.str());
      return std::nullopt;
    }

    const auto use_mocked = variables_map["mocked"].as<bool>();
    const auto model_path = variables_map["model"].as<std::string>();

    if (use_mocked && !model_path.empty()) {
      spdlog::error(
          "Invalid arguments: --mocked and --model are mutually exclusive");
      return std::nullopt;
    }

    if (!use_mocked && model_path.empty()) {
      spdlog::error(
          "Invalid arguments: Either --mocked or --model must be specified");
      return std::nullopt;
    }

    const bool has_llm_params = !variables_map["temperature"].defaulted() ||
                                !variables_map["top-p"].defaulted() ||
                                !variables_map["top-k"].defaulted() ||
                                !variables_map["seed"].defaulted();

    if (use_mocked && has_llm_params) {
      spdlog::warn(
          "Sampling parameters (--temperature, --top-p, --top-k, --seed) are"
          " ignored when using --mocked");
    }

    ApplicationOptions options;
    options.use_mocked = use_mocked;
    options.model_path = model_path;
    options.temperature = variables_map["temperature"].as<float>();
    options.top_p = variables_map["top-p"].as<float>();
    options.top_k = variables_map["top-k"].as<uint32_t>();
    options.n_ctx = variables_map["n-ctx"].as<uint32_t>();
    options.seed = variables_map["seed"].as<int>();

    return options;
  } catch (const std::exception& exception) {
    spdlog::error("Failed to parse command-line arguments: {}",
                  exception.what());
    return std::nullopt;
  } catch (...) {
    spdlog::error("Failed to parse command-line arguments: unknown error");
    return std::nullopt;
  }
}

struct Timer {
  std::chrono::steady_clock::time_point start_time =
      std::chrono::steady_clock::now();
  [[nodiscard]] int64_t Elapsed() const {
    return std::chrono::duration_cast<std::chrono::milliseconds>(
               std::chrono::steady_clock::now() - start_time)
        .count();
  }
};

int main(const int argc, char** argv) {
  try {
    Timer timer;
    const CurlGlobalState curl_state;
    const LlamaBackendState llama_backend_state;
    spdlog::set_pattern("[%Y-%m-%d %H:%M:%S.%e] [%^%l%$] %v");

    const auto parsed_options = ParseArguments(argc, argv);
    if (!parsed_options.has_value()) {
      return 0;
    }

    const auto options = *parsed_options;

    const auto injector = di::make_injector(
        di::bind<WebClient>().to<CURLWebClient>(),
        di::bind<ApplicationOptions>().to(options),
        di::bind<IEnrichmentService>().to<WikipediaService>(),
        di::bind<IPromptFormatter>().to<Gemma4JinjaPromptFormatter>(),
        di::bind<std::string>().to(options.model_path),
        di::bind<DataGenerator>().to(
            [options](const auto& inj) -> std::unique_ptr<DataGenerator> {
              if (options.use_mocked) {
                spdlog::info(
                    "[Generator] Using MockGenerator (no model path provided)");
                return std::make_unique<MockGenerator>();
              }

              spdlog::info(
                  "[Generator] Using LlamaGenerator: {} (temperature={}, "
                  "top-p={}, top-k={}, n_ctx={}, seed={})",
                  options.model_path, options.temperature, options.top_p,
                  options.top_k, options.n_ctx, options.seed);
              return inj.template create<std::unique_ptr<LlamaGenerator>>();
            }));

    auto generator = injector.create<BiergartenDataGenerator>();

    if (!generator.Run()) {
      spdlog::error("Pipeline execution failed");
      return 1;
    }

    spdlog::info("Pipeline executed successfully in {} ms", timer.Elapsed());
    return 0;
  } catch (const std::exception& exception) {
    spdlog::critical("Unhandled fatal error in main: {}", exception.what());
    return 1;
  }
}