#include "smartbotic/webserver/config.hpp"

#include <nlohmann/json.hpp>
#include <spdlog/spdlog.h>

#include <algorithm>
#include <cctype>
#include <cstdlib>
#include <filesystem>
#include <fstream>

namespace smartbotic::webserver {

auto LogLevelToString(LogLevel level) -> std::string {
    switch (level) {
        case LogLevel::kTrace:
            return "trace";
        case LogLevel::kDebug:
            return "debug";
        case LogLevel::kInfo:
            return "info";
        case LogLevel::kWarn:
            return "warn";
        case LogLevel::kError:
            return "error";
        case LogLevel::kCritical:
            return "critical";
        case LogLevel::kOff:
            return "off";
    }
    return "info";
}

auto ParseLogLevel(const std::string& str) -> std::optional<LogLevel> {
    std::string lower;
    lower.reserve(str.size());
    std::transform(str.begin(), str.end(), std::back_inserter(lower), [](unsigned char c) { return std::tolower(c); });

    if (lower == "trace")
        return LogLevel::kTrace;
    if (lower == "debug")
        return LogLevel::kDebug;
    if (lower == "info")
        return LogLevel::kInfo;
    if (lower == "warn" || lower == "warning")
        return LogLevel::kWarn;
    if (lower == "error" || lower == "err")
        return LogLevel::kError;
    if (lower == "critical" || lower == "crit" || lower == "fatal")
        return LogLevel::kCritical;
    if (lower == "off" || lower == "none")
        return LogLevel::kOff;

    return std::nullopt;
}

namespace {

auto GetEnvOrDefault(const char* name, const std::string& default_value) -> std::string {
    const char* value = std::getenv(name);
    return value != nullptr ? std::string(value) : default_value;
}

auto GetEnvOrDefault(const char* name, uint16_t default_value) -> uint16_t {
    const char* value = std::getenv(name);
    if (value == nullptr) {
        return default_value;
    }
    try {
        return static_cast<uint16_t>(std::stoi(value));
    } catch (...) {
        return default_value;
    }
}

auto GetEnvBool(const char* name, bool default_value) -> bool {
    const char* value = std::getenv(name);
    if (value == nullptr) {
        return default_value;
    }
    std::string str(value);
    std::transform(str.begin(), str.end(), str.begin(), [](unsigned char c) { return std::tolower(c); });
    return str == "true" || str == "1" || str == "yes";
}

}  // namespace

auto ConfigLoader::GetDefaultConfigPaths() -> std::vector<std::string> {
    std::vector<std::string> paths;

    // Current directory
    paths.emplace_back("./smartbotic-server.json");

    // Config subdirectory
    paths.emplace_back("./config/smartbotic-server.json");

    // /etc for system-wide config
    paths.emplace_back("/etc/smartbotic/smartbotic-server.json");

    // Home directory
    const char* home = std::getenv("HOME");
    if (home != nullptr) {
        paths.push_back(std::string(home) + "/.config/smartbotic/smartbotic-server.json");
    }

    return paths;
}

auto ConfigLoader::FindConfigFile() -> std::optional<std::string> {
    // Check environment variable for explicit config path
    const char* config_path_env = std::getenv("SMARTBOTIC_SERVER_CONFIG");
    if (config_path_env != nullptr && std::filesystem::exists(config_path_env)) {
        return std::string(config_path_env);
    }

    // Search default paths
    for (const auto& path : GetDefaultConfigPaths()) {
        if (std::filesystem::exists(path)) {
            return path;
        }
    }

    return std::nullopt;
}

auto ConfigLoader::LoadFromFile(const std::string& path) -> std::optional<HttpServerConfig> {
    try {
        if (!std::filesystem::exists(path)) {
            spdlog::warn("Config file not found: {}", path);
            return std::nullopt;
        }

        std::ifstream file(path);
        if (!file.is_open()) {
            spdlog::error("Failed to open config file: {}", path);
            return std::nullopt;
        }

        nlohmann::json json = nlohmann::json::parse(file);
        HttpServerConfig config;

        // Server section
        if (json.contains("server")) {
            const auto& server = json["server"];
            if (server.contains("address")) {
                config.address = server["address"].get<std::string>();
            }
            if (server.contains("port")) {
                config.port = server["port"].get<uint16_t>();
            }
            if (server.contains("webui_path")) {
                config.webui_path = server["webui_path"].get<std::string>();
            }
        }

        // WebSocket section
        if (json.contains("websocket")) {
            const auto& ws = json["websocket"];
            if (ws.contains("port")) {
                config.ws_port = ws["port"].get<uint16_t>();
            }
            if (ws.contains("path")) {
                config.ws_path = ws["path"].get<std::string>();
            }
        }

        // CORS section
        if (json.contains("cors")) {
            const auto& cors = json["cors"];
            if (cors.contains("enabled")) {
                config.cors.enabled = cors["enabled"].get<bool>();
            }
            if (cors.contains("allowed_origins")) {
                config.cors.allowed_origins.clear();
                for (const auto& origin : cors["allowed_origins"]) {
                    config.cors.allowed_origins.push_back(origin.get<std::string>());
                }
            }
            if (cors.contains("allowed_methods")) {
                config.cors.allowed_methods.clear();
                for (const auto& method : cors["allowed_methods"]) {
                    config.cors.allowed_methods.push_back(method.get<std::string>());
                }
            }
            if (cors.contains("allowed_headers")) {
                config.cors.allowed_headers.clear();
                for (const auto& header : cors["allowed_headers"]) {
                    config.cors.allowed_headers.push_back(header.get<std::string>());
                }
            }
            if (cors.contains("allow_credentials")) {
                config.cors.allow_credentials = cors["allow_credentials"].get<bool>();
            }
            if (cors.contains("max_age")) {
                config.cors.max_age = cors["max_age"].get<int>();
            }
        }

        // Logging section
        if (json.contains("logging")) {
            const auto& logging = json["logging"];
            if (logging.contains("level")) {
                auto level_str = logging["level"].get<std::string>();
                auto level = ParseLogLevel(level_str);
                if (level) {
                    config.log_level = *level;
                } else {
                    spdlog::warn("Invalid log level '{}', using default", level_str);
                }
            }
        }

        // Database section
        if (json.contains("database")) {
            const auto& database = json["database"];
            if (database.contains("address")) {
                config.database_address = database["address"].get<std::string>();
            }
        }

        // JWT section
        if (json.contains("jwt")) {
            const auto& jwt = json["jwt"];
            if (jwt.contains("secret")) {
                config.jwt.secret = jwt["secret"].get<std::string>();
            }
            if (jwt.contains("issuer")) {
                config.jwt.issuer = jwt["issuer"].get<std::string>();
            }
            if (jwt.contains("access_token_expiry")) {
                config.jwt.access_token_expiry = jwt["access_token_expiry"].get<int>();
            }
            if (jwt.contains("refresh_token_expiry")) {
                config.jwt.refresh_token_expiry = jwt["refresh_token_expiry"].get<int>();
            }
        }

        spdlog::info("Loaded configuration from: {}", path);
        return config;

    } catch (const nlohmann::json::exception& e) {
        spdlog::error("Failed to parse config file {}: {}", path, e.what());
        return std::nullopt;
    } catch (const std::exception& e) {
        spdlog::error("Error loading config file {}: {}", path, e.what());
        return std::nullopt;
    }
}

void ConfigLoader::ApplyEnvironment(HttpServerConfig& config) {
    // Server settings from environment
    config.address = GetEnvOrDefault("SMARTBOTIC_SERVER_ADDRESS", config.address);
    config.port = GetEnvOrDefault("SMARTBOTIC_SERVER_PORT", config.port);
    config.webui_path = GetEnvOrDefault("SMARTBOTIC_SERVER_WEBUI_PATH", config.webui_path);
    config.ws_path = GetEnvOrDefault("SMARTBOTIC_SERVER_WS_PATH", config.ws_path);

    // CORS settings from environment
    config.cors.enabled = GetEnvBool("SMARTBOTIC_SERVER_CORS_ENABLED", config.cors.enabled);

    // Database settings from environment
    config.database_address = GetEnvOrDefault("SMARTBOTIC_SERVER_DATABASE_ADDRESS", config.database_address);

    // JWT settings from environment (secret from env is recommended for security)
    config.jwt.secret = GetEnvOrDefault("SMARTBOTIC_SERVER_JWT_SECRET", config.jwt.secret);

    // Log level from environment
    const char* log_level_env = std::getenv("SMARTBOTIC_SERVER_LOG_LEVEL");
    if (log_level_env != nullptr) {
        auto level = ParseLogLevel(log_level_env);
        if (level) {
            config.log_level = *level;
        }
    }
}

auto ConfigLoader::ParseCommandLine(int argc, char* argv[], HttpServerConfig& config) -> std::optional<bool> {
    std::string config_file_override;

    for (int i = 1; i < argc; ++i) {
        std::string arg = argv[i];

        if (arg == "--help" || arg == "-h") {
            PrintHelp(argv[0]);
            return std::nullopt;
        }

        if (arg == "--version" || arg == "-v") {
            spdlog::info("SmartBotic Web Server v0.1.0");
            return std::nullopt;
        }

        if (arg == "--config" || arg == "-c") {
            if (i + 1 < argc) {
                config_file_override = argv[++i];
            } else {
                spdlog::error("--config requires a path argument");
                return false;
            }
            continue;
        }

        if (arg == "--port" || arg == "-p") {
            if (i + 1 < argc) {
                try {
                    config.port = static_cast<uint16_t>(std::stoi(argv[++i]));
                } catch (...) {
                    spdlog::error("Invalid port number: {}", argv[i]);
                    return false;
                }
            } else {
                spdlog::error("--port requires a number argument");
                return false;
            }
            continue;
        }

        if (arg == "--address" || arg == "-a") {
            if (i + 1 < argc) {
                config.address = argv[++i];
            } else {
                spdlog::error("--address requires an address argument");
                return false;
            }
            continue;
        }

        if (arg == "--webui-path" || arg == "-w") {
            if (i + 1 < argc) {
                config.webui_path = argv[++i];
            } else {
                spdlog::error("--webui-path requires a path argument");
                return false;
            }
            continue;
        }

        if (arg == "--database" || arg == "-d") {
            if (i + 1 < argc) {
                config.database_address = argv[++i];
            } else {
                spdlog::error("--database requires an address argument");
                return false;
            }
            continue;
        }

        if (arg == "--log-level" || arg == "-l") {
            if (i + 1 < argc) {
                auto level = ParseLogLevel(argv[++i]);
                if (level) {
                    config.log_level = *level;
                } else {
                    spdlog::error("Invalid log level: {}", argv[i]);
                    return false;
                }
            } else {
                spdlog::error("--log-level requires a level argument");
                return false;
            }
            continue;
        }

        if (arg == "--no-cors") {
            config.cors.enabled = false;
            continue;
        }

        spdlog::error("Unknown argument: {}", arg);
        PrintHelp(argv[0]);
        return false;
    }

    // If config file was specified on command line, load it
    if (!config_file_override.empty()) {
        auto file_config = LoadFromFile(config_file_override);
        if (!file_config) {
            spdlog::error("Failed to load specified config file: {}", config_file_override);
            return false;
        }
        config = *file_config;

        // Re-parse command line to override file settings
        for (int i = 1; i < argc; ++i) {
            std::string arg = argv[i];
            if (arg == "--config" || arg == "-c") {
                ++i;
                continue;
            }
            if ((arg == "--port" || arg == "-p") && i + 1 < argc) {
                config.port = static_cast<uint16_t>(std::stoi(argv[++i]));
            } else if ((arg == "--address" || arg == "-a") && i + 1 < argc) {
                config.address = argv[++i];
            } else if ((arg == "--webui-path" || arg == "-w") && i + 1 < argc) {
                config.webui_path = argv[++i];
            } else if ((arg == "--database" || arg == "-d") && i + 1 < argc) {
                config.database_address = argv[++i];
            } else if ((arg == "--log-level" || arg == "-l") && i + 1 < argc) {
                auto level = ParseLogLevel(argv[++i]);
                if (level)
                    config.log_level = *level;
            } else if (arg == "--no-cors") {
                config.cors.enabled = false;
            }
        }
    }

    return true;
}

auto ConfigLoader::Load(int argc, char* argv[]) -> HttpServerConfig {
    HttpServerConfig config = HttpServerConfig::Default();

    // 1. Try to find and load config file
    auto config_file = FindConfigFile();
    if (config_file) {
        auto file_config = LoadFromFile(*config_file);
        if (file_config) {
            config = *file_config;
        }
    }

    // 2. Apply environment variables
    ApplyEnvironment(config);

    // 3. Parse command-line arguments
    auto result = ParseCommandLine(argc, argv, config);
    if (!result.has_value()) {
        std::exit(0);
    }
    if (!result.value()) {
        std::exit(1);
    }

    return config;
}

void ConfigLoader::PrintHelp(const char* program_name) {
    spdlog::info("Usage: {} [options]", program_name);
    spdlog::info("");
    spdlog::info("SmartBotic Web Server - HTTP/WebSocket Server");
    spdlog::info("");
    spdlog::info("Options:");
    spdlog::info("  -h, --help                 Show this help message");
    spdlog::info("  -v, --version              Show version information");
    spdlog::info("  -c, --config <path>        Path to config file (default: smartbotic-server.json)");
    spdlog::info("  -p, --port <port>          Port to listen on (default: 8080)");
    spdlog::info("  -a, --address <addr>       Address to bind to (default: 0.0.0.0)");
    spdlog::info("  -w, --webui-path <path>    Path to WebUI static files (default: ./webui/dist)");
    spdlog::info("  -d, --database <addr>      Database gRPC address (default: 127.0.0.1:50051)");
    spdlog::info("  -l, --log-level <level>    Log level: trace, debug, info, warn, error, critical, off");
    spdlog::info("  --no-cors                  Disable CORS headers");
    spdlog::info("");
    spdlog::info("Environment Variables:");
    spdlog::info("  SMARTBOTIC_SERVER_CONFIG           Path to config file");
    spdlog::info("  SMARTBOTIC_SERVER_ADDRESS          Address to bind to");
    spdlog::info("  SMARTBOTIC_SERVER_PORT             Port to listen on");
    spdlog::info("  SMARTBOTIC_SERVER_WEBUI_PATH       Path to WebUI static files");
    spdlog::info("  SMARTBOTIC_SERVER_DATABASE_ADDRESS Database gRPC address");
    spdlog::info("  SMARTBOTIC_SERVER_LOG_LEVEL        Log level");
    spdlog::info("  SMARTBOTIC_SERVER_CORS_ENABLED     Enable/disable CORS (true/false)");
    spdlog::info("");
    spdlog::info("Config File Search Order:");
    for (const auto& path : GetDefaultConfigPaths()) {
        spdlog::info("  {}", path);
    }
}

void ConfigLoader::PrintConfig(const HttpServerConfig& config) {
    spdlog::info("Configuration:");
    spdlog::info("  Address:          {}", config.address);
    spdlog::info("  Port:             {}", config.port);
    spdlog::info("  WebUI Path:       {}", config.webui_path);
    spdlog::info("  WebSocket Port:   {}", config.ws_port);
    spdlog::info("  WebSocket Path:   {}", config.ws_path);
    spdlog::info("  Database Address: {}", config.database_address);
    spdlog::info("  Log Level:        {}", LogLevelToString(config.log_level));
    spdlog::info("  CORS Enabled:     {}", config.cors.enabled ? "yes" : "no");
    if (config.cors.enabled) {
        std::string origins;
        for (size_t i = 0; i < config.cors.allowed_origins.size(); ++i) {
            if (i > 0) {
                origins += ", ";
            }
            origins += config.cors.allowed_origins[i];
        }
        spdlog::info("  CORS Origins:     {}", origins);
    }
    spdlog::info("  JWT Issuer:       {}", config.jwt.issuer);
    spdlog::info("  JWT Secret:       {}", config.jwt.secret.empty() ? "(not configured)" : "(configured)");
    spdlog::info("  JWT Access TTL:   {}s", config.jwt.access_token_expiry);
    spdlog::info("  JWT Refresh TTL:  {}s", config.jwt.refresh_token_expiry);
}

}  // namespace smartbotic::webserver