#include "core/resources/resource_helper.hpp"

#include <fstream>
#include <iostream>
#include <string>
#include <string_view>

#include "core/resources/resource_pack.hpp"

namespace Resource::Helper {

    namespace {

        std::string g_data_root;
        Pack g_pack;
        bool g_pack_loaded = false;
        bool g_fallback_enabled = true;

        auto readFromDisk(const std::string& filepath) -> std::vector<std::uint8_t> {
            const auto FULL = resolve(filepath);
            std::ifstream file(FULL, std::ios::binary | std::ios::ate);
            if (!file) {
                std::cerr << "Resource::Helper: cannot open " << FULL << '\n';
                return {};
            }
            std::streamsize size = file.tellg();
            file.seekg(0, std::ios::beg);
            std::vector<std::uint8_t> data(static_cast<std::size_t>(size));
            if (!file.read(reinterpret_cast<char*>(data.data()), size)) {
                std::cerr << "Resource::Helper: failed to read " << FULL << '\n';
                return {};
            }
            return data;
        }

    }  // namespace

    auto initializeResourceSystem(const std::string& pack_file, bool enable_fallback) -> bool {
        g_fallback_enabled = enable_fallback;
        g_pack_loaded = g_pack.loadPack(pack_file);

        if (g_pack_loaded) {
            std::cout << "Resource::Helper: pack loaded (" << g_pack.getResourceCount()
                      << " entries) from " << pack_file << '\n';
        } else if (enable_fallback) {
            std::cout << "Resource::Helper: no pack at " << pack_file
                      << " — using filesystem fallback\n";
        } else {
            std::cerr << "Resource::Helper: FATAL — no pack at " << pack_file
                      << " and fallback disabled\n";
            return false;
        }
        return true;
    }

    void shutdownResourceSystem() {
        g_pack.clear();
        g_pack_loaded = false;
    }

    auto hasPack() -> bool {
        return g_pack_loaded;
    }

    void setDataRoot(const std::string& absolute_path) {
        g_data_root = absolute_path;
        if (!g_data_root.empty() && g_data_root.back() != '/') {
            g_data_root += '/';
        }
    }

    auto resolve(const std::string& filepath) -> std::string {
        if (filepath.empty() || filepath.front() == '/') { return filepath; }
        if (g_data_root.empty()) { return filepath; }
        return g_data_root + filepath;
    }

    auto loadFile(const std::string& filepath) -> std::vector<std::uint8_t> {
        if (g_pack_loaded) {
            // El pack està indexat relatiu a `data/` (la carpeta que
            // s'empaqueta), però els callers passen "data/foo.yaml" amb
            // prefix. Fem el strip ací perquè no hagin de tenir-ho en compte.
            constexpr std::string_view PREFIX = "data/";
            std::string key = filepath;
            if (key.starts_with(PREFIX)) { key.erase(0, PREFIX.size()); }
            if (g_pack.hasResource(key)) { return g_pack.getResource(key); }
        }
        if (g_fallback_enabled) { return readFromDisk(filepath); }
        return {};
    }

}  // namespace Resource::Helper