// GNU Lesser General Public License v3.0
// Copyright (c) 2025 Bart Beumer <bart@4beumer.nl>
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License v3.0 as published by
// the Free Software Foundation.
//
#include <bmrshared/directory_request_handler.hpp>
#include <algorithm>
#include <array>
#include <bmrshared/magic_file_info.hpp>
#include <bmrshared/response_promise.hpp>
#include <filesystem>
#include <future>
#include <iomanip>
#include <iostream>
#include <optional>
#include <string_view>

namespace beast = boost::beast;
namespace http = beast::http;

namespace
{
struct ExtensionMimeMapping
{
    std::string_view extension;
    std::string_view mime;
};

bmrshared::magic_file_info mfi("magic.mgc");

} // namespace

using bmrshared::web::directory_request_handler;


directory_request_handler::directory_request_handler(const std::filesystem::path& document_root)
    : m_document_root(std::filesystem::absolute(document_root))
{
}

directory_request_handler::~directory_request_handler() = default;

void directory_request_handler::handle_request_http(const address_type& address,
                                            const request_type& req,
                                            bmrshared::web::response_promise promise)
{
    if ((req.method() != http::verb::get) && (req.method() != http::verb::head))
    {
        // Other methods are not supported for directory acces
        //
        http::response<http::string_body> bad_request{http::status::bad_request, req.version()};
        bad_request.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        bad_request.set(http::field::content_type, "text/plain");
        bad_request.prepare_payload();
        bad_request.body() = "Bad request type.\nOnly GET and HEAD are expected for this URL.";
        bad_request.keep_alive(req.keep_alive());
        promise.SendResponse(std::move(bad_request));
        return;
    }

    std::string_view target = req.target();
    {
        target.remove_prefix(std::min(target.find_first_not_of(R"(/\)"), target.size()));
    }

    std::filesystem::path requested_file = m_document_root / std::filesystem::path(target);
    std::optional<std::filesystem::path> found_file;

    // See if requested path is a directory, use index.html if that is the case.
    if (std::filesystem::is_directory(requested_file))
    {
        auto indexPath = requested_file / "index.html";
        if (std::filesystem::is_regular_file(indexPath))
        {
            found_file = indexPath;
        }
    }

    // See if requested path is a file.
    if (std::filesystem::is_regular_file(requested_file))
    {
        found_file = requested_file;
    }

    if (!found_file)
    {
        http::response<http::string_body> not_found{http::status::not_found, req.version()};
        not_found.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        not_found.set(http::field::content_type, "text/plain");
        not_found.prepare_payload();
        not_found.body() = "File not found.";
        not_found.keep_alive(req.keep_alive());
        promise.SendResponse(std::move(not_found));
        return;
    }


    beast::error_code ec;
    http::file_body::value_type body;
    body.open(found_file->native().c_str(), beast::file_mode::scan, ec);
    if (ec)
    {
        http::response<http::string_body> internal{http::status::internal_server_error, req.version()};
        internal.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        internal.set(http::field::content_type, "text/plain");
        internal.prepare_payload();
        internal.body() = "Internal server error.";
        internal.keep_alive(req.keep_alive());
        promise.SendResponse(std::move(internal));
        return;
    }

    const auto file_size = body.size();
    const auto file_last_modified_utc = std::chrono::time_point_cast<std::chrono::seconds>(std::filesystem::last_write_time(*found_file));
    const std::string last_modified = std::format("{0:%a}, {0:0>2%d} {0:0>2%e} {0:0>4%Y} {0:%H}:{0:%M}:{0:%S} GMT", file_last_modified_utc);
    const std::string mime_type = mfi.get_mime(*found_file);
    
    if (req.count(http::field::if_modified_since) != 0 && (req[http::field::if_modified_since] == last_modified))
    {
        http::response<http::string_body> head{http::status::not_modified, req.version()};
        head.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        head.keep_alive(req.keep_alive());
        promise.SendResponse(std::move(head));
        return;
    }


    // Okay, we have a file so let us send the correct response.
    if (req.method() == http::verb::head)
    {
        http::response<http::string_body> head{http::status::ok, req.version()};
        head.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        head.set(http::field::content_type, mime_type);
        head.set(http::field::last_modified, last_modified);
        head.set(http::field::cache_control, "public, max-age=360");
        head.set(http::field::content_length, std::to_string(file_size));
        head.keep_alive(req.keep_alive());
        promise.SendResponse(std::move(head));
        return;
    }
    else if (req.method() == http::verb::get)
    {
        http::response<http::file_body> head{std::piecewise_construct,
                                        std::make_tuple(std::move(body)),
                                        std::make_tuple(http::status::ok, req.version())};

        head.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        head.set(http::field::content_type, mime_type);
        head.set(http::field::last_modified, last_modified);
        head.set(http::field::cache_control, "public, max-age=360");
        head.set(http::field::content_length, std::to_string(file_size));
        head.keep_alive(req.keep_alive());
        //promise.SendResponse(std::move(head));
        return;
    }
}

void directory_request_handler::handle_request_websocket_upgrade(const address_type&,
                                                         const request_type&,
                                                         boost::asio::ip::tcp::socket)
{
    // We ignore websocket upgrades. throw away the socket to close connection.
}