#include "../include/DownloadUtils.hpp"
#include "../include/Program.hpp"
#include "../include/Storage.hpp"
#include "../include/NetUtils.hpp"
#include "../external/hash-library/sha256.h"
#include <unistd.h>
#include <limits.h>
#include <mglpp/system/Clock.hpp>
#include <mglpp/window/Event.hpp>
#include <rapidjson/document.h>
#include <rapidjson/filereadstream.h>

namespace QuickMedia {
    struct DownloadUserdata {
        std::vector<std::string> *headers = nullptr;
        std::string *body = nullptr;
        int64_t download_limit = 1024 * 1024 * 100; // 100mb
        bool headers_finished = false;
        int64_t total_downloaded_size = 0;
    };

    static int accumulate_string(char *data, int size, void *userdata) {
        std::string *str = (std::string*)userdata;
        if(str->size() + size > 1024 * 1024 * 100) // 100mb sane limit, TODO: make configurable
            return 1;
        str->append(data, size);
        return 0;
    }

    static bool http_is_redirect(const char *header, size_t size) {
        const void *end_of_first_line_p = memmem(header, size, "\r\n", 2);
        if(!end_of_first_line_p)
            return false;
        return memmem(header, (const char*)end_of_first_line_p - header, " 30", 3) != nullptr;
    }

    static int accumulate_string_with_header(char *data, int size, void *userdata) {
        DownloadUserdata *download_userdata = (DownloadUserdata*)userdata;

        if(download_userdata->headers_finished) {
            download_userdata->body->append(data, size);
        } else {
            if(download_userdata->headers->empty())
                download_userdata->headers->push_back("");

            std::string *current_header = &download_userdata->headers->back();
            current_header->append(data, size);

            bool end_of_header_found = false;
            size_t end_of_headers_index = current_header->find("\r\n\r\n");
            if(end_of_headers_index != std::string::npos) {
                while(true) {
                    const bool is_redirect = http_is_redirect(current_header->c_str(), end_of_headers_index);
                    end_of_headers_index += 4;
                    if(is_redirect) {
                        std::string header_after_this_header = current_header->substr(end_of_headers_index);
                        current_header->erase(current_header->begin() + end_of_headers_index, current_header->end());
                        download_userdata->headers->push_back(std::move(header_after_this_header));
                        current_header = &download_userdata->headers->back();
                        end_of_headers_index = current_header->find("\r\n\r\n");
                        if(end_of_headers_index == std::string::npos)
                            break;
                    } else {
                        end_of_header_found = true;
                        break;
                    }
                }
            }

            if(end_of_header_found) {
                download_userdata->body->append(current_header->begin() + end_of_headers_index, current_header->end());
                current_header->erase(current_header->begin() + end_of_headers_index, current_header->end());
                download_userdata->headers_finished = true;
            }
        }

        download_userdata->total_downloaded_size += size;
        if(download_userdata->total_downloaded_size >= download_userdata->download_limit)
            return 1;

        return 0;
    }

    static const bool debug_download = false;
    static const char *useragent_str = "user-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36";

    DownloadResult download_head_to_string(const std::string &url, std::string &result, bool use_browser_useragent, bool fail_on_error) {
        result.clear();
        mgl::Clock timer;
        std::vector<const char*> args;
        args.insert(args.end(), { "curl", "-I", "-g", "-H", "Accept-Language: en-US,en;q=0.5", "-H", "Connection: keep-alive", "--compressed", "-s" });
        if(fail_on_error)
            args.push_back("-f");
        if(use_browser_useragent) {
            args.push_back("-H");
            args.push_back(useragent_str);
        }
        args.push_back("--");
        args.push_back(url.c_str());
        args.push_back(nullptr);
        if(debug_download) {
            for(const char *arg : args) {
                if(arg)
                    fprintf(stderr, "'%s' ", arg);
            }
            fprintf(stderr, "\n");
        }
        if(exec_program(args.data(), accumulate_string, &result) != 0)
            return DownloadResult::NET_ERR;
        fprintf(stderr, "Download duration for %s: %d ms\n", url.c_str(), (int)(timer.get_elapsed_time_seconds() * 1000.0));
        return DownloadResult::OK;
    }

    DownloadResult url_get_remote_name(const std::string &url, std::string &result, bool use_browser_useragent) {
        result.clear();
        mgl::Clock timer;
        std::vector<const char*> args;
        args.insert(args.end(), { "curl", "-I", "-g", "-H", "Accept-Language: en-US,en;q=0.5", "-H", "Connection: keep-alive", "--compressed", "-s" });
        if(use_browser_useragent) {
            args.push_back("-H");
            args.push_back(useragent_str);
        }
        args.push_back("--");
        args.push_back(url.c_str());
        args.push_back(nullptr);
        if(debug_download) {
            for(const char *arg : args) {
                if(arg)
                    fprintf(stderr, "'%s' ", arg);
            }
            fprintf(stderr, "\n");
        }
        std::string header;
        if(exec_program(args.data(), accumulate_string, &header) != 0)
            return DownloadResult::NET_ERR;
        fprintf(stderr, "Download duration for %s: %d ms\n", url.c_str(), (int)(timer.get_elapsed_time_seconds() * 1000.0));

        std::string content_disposition = header_extract_value(header, "content-disposition");
        // TODO: after filename*= the encoding type will follow. We need to support other formats than utf-8 as well
        size_t filename_start = content_disposition.find("filename*=");
        if(filename_start == std::string::npos) {
            filename_start = content_disposition.find("filename=");
            if(filename_start != std::string::npos) {
                filename_start += 9;
            }
        } else {
            filename_start += 10;
            filename_start = content_disposition.find("''", filename_start);
            if(filename_start != std::string::npos)
                filename_start += 2;
        }

        if(filename_start == std::string::npos) {
            size_t filename_start = url.rfind('/');
            if(filename_start == std::string::npos) {
                result = "";
                return DownloadResult::OK;
            }

            ++filename_start;
            size_t filename_end = url.size();
            for(size_t i = filename_start; i < url.size(); ++i) {
                char c = url[i];
                if(c == '/' || c == '&' || c == '?') {
                    filename_end = i;
                    break;
                }
            }

            result = url_param_decode(url.substr(filename_start, filename_end - filename_start));
            return DownloadResult::OK;
        } else {
            for(size_t i = filename_start; i < content_disposition.size(); ++i) {
                char c = content_disposition[i];
                if(c != '"' && c != ' ') {
                    filename_start = i;
                    break;
                }
            }

            size_t filename_end = content_disposition.size();
            for(int i = filename_end - 1; i >= (int)filename_start; --i) {
                char c = content_disposition[i];
                if(c != '"' && c != ' ' && c != '\n' && c != '\r') {
                    filename_end = i + 1;
                    break;
                }
            }

            result = url_param_decode(content_disposition.substr(filename_start, filename_end - filename_start));
            return DownloadResult::OK;
        }
    }

    // TODO: Add timeout
    DownloadResult download_to_string(const std::string &url, std::string &result, const std::vector<CommandArg> &additional_args, bool use_browser_useragent, bool fail_on_error, bool cloudflare_bypass, std::vector<std::string> *headers, int download_limit) {
        result.clear();
        mgl::Clock timer;
        std::vector<const char*> args;

        if(cloudflare_bypass) {
            args.insert(args.end(), { "wget", "--header", "Accept-Language: en-US,en;q=0.5", "-q", "-O", "-" });
            // TODO:
            //if(fail_on_error)
            //    args.push_back("-f");
            // TODO: May not be compatible
            for(const CommandArg &arg : additional_args) {
                args.push_back(arg.option.c_str());
                if(!arg.value.empty())
                    args.push_back(arg.value.c_str());
            }
            if(use_browser_useragent) {
                args.push_back("--header");
                args.push_back(useragent_str);
            }
            // TODO:
            //if(headers)
            //    args.push_back("-i");
        } else {
            args.insert(args.end(), { "curl", "-H", "Accept-Language: en-US,en;q=0.5", "-H", "Connection: keep-alive", "--compressed", "-g", "-s", "-L" });
            if(fail_on_error)
                args.push_back("-f");
            for(const CommandArg &arg : additional_args) {
                args.push_back(arg.option.c_str());
                if(!arg.value.empty())
                    args.push_back(arg.value.c_str());
            }
            if(use_browser_useragent) {
                args.push_back("-H");
                args.push_back(useragent_str);
            }
            if(headers)
                args.push_back("-i");
        }
        args.push_back("--");
        args.push_back(url.c_str());
        args.push_back(nullptr);

        if(debug_download) {
            for(const char *arg : args) {
                if(arg)
                    fprintf(stderr, "'%s' ", arg);
            }
            fprintf(stderr, "\n");
        }

        DownloadUserdata download_userdata;
        download_userdata.headers = headers;
        download_userdata.body = &result;
        download_userdata.download_limit = download_limit;
        download_userdata.headers_finished = !headers;

        if(exec_program(args.data(), accumulate_string_with_header, &download_userdata) != 0)
            return DownloadResult::NET_ERR;

        fprintf(stderr, "Download duration for %s: %d ms\n", url.c_str(), (int)(timer.get_elapsed_time_seconds() * 1000.0));
        return DownloadResult::OK;
    }

    DownloadResult download_to_string_cache(const std::string &url, std::string &result, const std::vector<CommandArg> &additional_args, bool use_browser_useragent, DownloadErrorHandler error_handler, Path cache_path) {
        result.clear();
        Path media_file_path;
        if(cache_path.data.empty()) {
            SHA256 sha256;
            sha256.add(url.data(), url.size());
            media_file_path = get_cache_dir().join("media").join(sha256.getHash());
        } else {
            media_file_path = std::move(cache_path);
        }

        if(get_file_type(media_file_path) == FileType::REGULAR) {
            if(file_get_content(media_file_path, result) == 0) {
                fprintf(stderr, "Loaded %s from cache\n", url.c_str());
                return DownloadResult::OK;
            } else {
                fprintf(stderr, "Failed to get content of cached media file: %s\n", media_file_path.data.c_str());
                return DownloadResult::ERR;
            }
        } else {
            DownloadResult download_result = download_to_string(url, result, additional_args, use_browser_useragent, error_handler ? false : true);
            if(download_result == DownloadResult::OK && error_handler)
                download_result = error_handler(result) ? DownloadResult::OK : DownloadResult::ERR;
            if(download_result == DownloadResult::OK)
                download_result = file_overwrite_atomic(media_file_path, result) == 0 ? DownloadResult::OK : DownloadResult::ERR;
            return download_result;
        }
    }

    DownloadResult download_to_file(const std::string &url, const std::string &destination_filepath, const std::vector<CommandArg> &additional_args, bool use_browser_useragent, bool cloudflare_bypass) {
        Path tmp_filepath = destination_filepath;
        tmp_filepath.append(".tmp");

        // TODO: Optimize with temporary '\0'
        size_t dir_end = tmp_filepath.data.rfind('/');
        if(dir_end != std::string::npos && create_directory_recursive(tmp_filepath.data.substr(0, dir_end)) != 0)
            return DownloadResult::ERR;

        std::vector<CommandArg> args = additional_args;
        args.push_back({ "-o", tmp_filepath.data.c_str() });

        std::string dummy;
        DownloadResult res = download_to_string(url, dummy, std::move(args), use_browser_useragent, true, cloudflare_bypass);
        if(res != DownloadResult::OK) return res;
        
        if(rename_atomic(tmp_filepath.data.c_str(), destination_filepath.c_str()) != 0) {
            perror("rename");
            return DownloadResult::ERR;
        }

        return DownloadResult::OK;
    }

    bool download_async_gui(const std::string &url, const std::string &file_manager_start_dir, bool no_video) {
        char quickmedia_path[PATH_MAX];
        ssize_t bytes_written = readlink("/proc/self/exe", quickmedia_path, sizeof(quickmedia_path) - 1);
        if(bytes_written == -1)
            strcpy(quickmedia_path, "quickmedia");
        else
            quickmedia_path[bytes_written] = '\0';

        std::vector<const char*> args = { quickmedia_path, "download", "-u", url.c_str(), "--dir", file_manager_start_dir.c_str() };
        if(no_video) args.push_back("--no-video");
        args.push_back(nullptr);
        return exec_program_async(args.data(), nullptr) == 0;
    }

    // TODO: Add timeout
    DownloadResult download_to_json(const std::string &url, rapidjson::Document &result, const std::vector<CommandArg> &additional_args, bool use_browser_useragent, bool fail_on_error) {
        mgl::Clock timer;
        std::vector<const char*> args;
        args.insert(args.end(), { "curl", "-H", "Accept-Language: en-US,en;q=0.5", "-H", "Connection: keep-alive", "--compressed", "-g", "-s", "-L" });
        if(fail_on_error)
            args.push_back("-f");
        for(const CommandArg &arg : additional_args) {
            args.push_back(arg.option.c_str());
            if(!arg.value.empty())
                args.push_back(arg.value.c_str());
        }
        if(use_browser_useragent) {
            args.push_back("-H");
            args.push_back(useragent_str);
        }
        args.push_back("--");
        args.push_back(url.c_str());
        args.push_back(nullptr);
        if(debug_download) {
            for(const char *arg : args) {
                if(arg)
                    fprintf(stderr, "'%s' ", arg);
            }
            fprintf(stderr, "\n");
        }

        ReadProgram read_program;
        if(exec_program_pipe(args.data(), &read_program) != 0)
            return DownloadResult::NET_ERR;
        
        FILE *file = fdopen(read_program.read_fd, "rb");
        if(!file) {
            program_clear_current_thread();
            wait_program(read_program.pid);
            return DownloadResult::ERR;
        }

        char read_buffer[8192];
        rapidjson::FileReadStream is(file, read_buffer, sizeof(read_buffer));
        rapidjson::ParseResult parse_result = result.ParseStream(is);
        program_clear_current_thread();

        fclose(file);
        wait_program(read_program.pid);
        fprintf(stderr, "Download duration for %s: %d ms\n", url.c_str(), (int)(timer.get_elapsed_time_seconds() * 1000.0));
        return parse_result.IsError() ? DownloadResult::ERR : DownloadResult::OK;
    }
}