// resource_loader.cpp
// Resource loader implementation

#include "resource_loader.hpp"

#include <filesystem>
#include <fstream>
#include <iostream>

namespace Resource {

// Get singleton instance
auto Loader::get() -> Loader& {
    static Loader instance_;
    return instance_;
}

// Initialize with a pack file
auto Loader::initialize(const std::string& pack_file, bool enable_fallback)
    -> bool {
    if (initialized_) {
        std::cout << "Loader: Already initialized\n";
        return true;
    }

    fallback_to_files_ = enable_fallback;

    // Try to load the pack file
    if (!pack_file.empty() && fileExistsOnFilesystem(pack_file)) {
        std::cout << "Loader: Loading pack file: " << pack_file << '\n';
        resource_pack_ = std::make_unique<Pack>();
        if (resource_pack_->loadPack(pack_file)) {
            std::cout << "Loader: Pack loaded successfully\n";
            initialized_ = true;
            return true;
        }
        std::cerr << "Loader: Failed to load pack file\n";
        resource_pack_.reset();
    } else {
        std::cout << "Loader: Pack file not found: " << pack_file << '\n';
    }

    // If pack loading failed and fallback is disabled, fail
    if (!fallback_to_files_) {
        std::cerr << "Loader: Pack required but not found (fallback disabled)\n";
        return false;
    }

    // Otherwise, fallback to filesystem
    std::cout << "Loader: Using filesystem fallback\n";
    initialized_ = true;
    return true;
}

// Load a resource
auto Loader::loadResource(const std::string& filename) -> std::vector<uint8_t> {
    if (!initialized_) {
        std::cerr << "Loader: Not initialized\n";
        return {};
    }

    // Try pack first if available
    if (resource_pack_ && resource_pack_->isLoaded()) {
        if (resource_pack_->hasResource(filename)) {
            auto data = resource_pack_->getResource(filename);
            if (!data.empty()) {
                return data;
            }
            std::cerr << "Loader: Failed to extract from pack: " << filename
                      << '\n';
        }
    }

    // Fallback to filesystem if enabled
    if (fallback_to_files_) {
        return loadFromFilesystem(filename);
    }

    std::cerr << "Loader: Resource not found: " << filename << '\n';
    return {};
}

// Check if a resource exists
auto Loader::resourceExists(const std::string& filename) -> bool {
    if (!initialized_) {
        return false;
    }

    // Check pack first
    if (resource_pack_ && resource_pack_->isLoaded()) {
        if (resource_pack_->hasResource(filename)) {
            return true;
        }
    }

    // Check filesystem if fallback enabled
    if (fallback_to_files_) {
        return fileExistsOnFilesystem(filename);
    }

    return false;
}

// Check if pack is loaded
auto Loader::isPackLoaded() const -> bool {
    return resource_pack_ && resource_pack_->isLoaded();
}

// Get pack statistics
auto Loader::getPackResourceCount() const -> size_t {
    if (resource_pack_ && resource_pack_->isLoaded()) {
        return resource_pack_->getResourceCount();
    }
    return 0;
}

// Cleanup
void Loader::shutdown() {
    resource_pack_.reset();
    initialized_ = false;
    std::cout << "Loader: Shutdown complete\n";
}

// Load from filesystem
auto Loader::loadFromFilesystem(const std::string& filepath)
    -> std::vector<uint8_t> {
    std::ifstream file(filepath, std::ios::binary | std::ios::ate);
    if (!file) {
        return {};
    }

    std::streamsize file_size = file.tellg();
    file.seekg(0, std::ios::beg);

    std::vector<uint8_t> data(file_size);
    if (!file.read(reinterpret_cast<char*>(data.data()), file_size)) {
        std::cerr << "Loader: Failed to read file: " << filepath << '\n';
        return {};
    }

    return data;
}

// Check if file exists on filesystem
auto Loader::fileExistsOnFilesystem(const std::string& filepath) -> bool {
    return std::filesystem::exists(filepath);
}

// Validate pack integrity
auto Loader::validatePack() const -> bool {
    if (!initialized_ || !resource_pack_ || !resource_pack_->isLoaded()) {
        std::cerr << "Loader: Cannot validate - pack not loaded\n";
        return false;
    }

    // Calculate pack checksum
    uint32_t checksum = resource_pack_->calculatePackChecksum();

    if (checksum == 0) {
        std::cerr << "Loader: Pack checksum is zero (invalid)\n";
        return false;
    }

    std::cout << "Loader: Pack checksum: 0x" << std::hex << checksum << std::dec
              << '\n';
    std::cout << "Loader: Pack validation successful\n";
    return true;
}

// Load assets.yaml from pack
auto Loader::loadAssetsConfig() const -> std::string {
    if (!initialized_ || !resource_pack_ || !resource_pack_->isLoaded()) {
        std::cerr << "Loader: Cannot load assets config - pack not loaded\n";
        return "";
    }

    // Try to load config/assets.yaml from pack
    std::string config_path = "config/assets.yaml";

    if (!resource_pack_->hasResource(config_path)) {
        std::cerr << "Loader: assets.yaml not found in pack: " << config_path << '\n';
        return "";
    }

    auto data = resource_pack_->getResource(config_path);
    if (data.empty()) {
        std::cerr << "Loader: Failed to load assets.yaml from pack\n";
        return "";
    }

    // Convert bytes to string
    std::string config_content(data.begin(), data.end());
    std::cout << "Loader: Loaded assets.yaml from pack (" << data.size()
              << " bytes)\n";

    return config_content;
}

}  // namespace Resource