#include "../include/Storage.hpp"
#include "../include/StringUtils.hpp"
#include "../include/Notification.hpp"
#include <stdio.h>
#include <assert.h>
#include <json/reader.h>
#include <json/writer.h>
#include <rapidjson/document.h>
#include <rapidjson/writer.h>
#include <rapidjson/stringbuffer.h>
#include <unordered_set>
#include <filesystem>
#include <algorithm>

#include <pwd.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>

#define EINTR_RETRY(ret, expr)              \
    do {                                    \
        errno = 0;                          \
        while(true) {                       \
            ret = (expr);                   \
            if(ret != -1 || errno != EINTR) \
                break;                      \
        }                                   \
    } while(0)

static int makedir(const char *path) {
    return mkdir(path, S_IRWXU);
}

namespace QuickMedia {
    static FILE* fopen_eintr(const char *filename, const char *modes) {
        errno = 0;
        while(true) {
            FILE *f = fopen(filename, modes);
            if(f || errno != EINTR)
                return f;
        }
    }   

    static size_t fwrite_eintr(const char *data, size_t size, FILE *f) {
        errno = 0;
        while(true) {
            const size_t r = fwrite(data, 1, size, f); 
            if(r == size || errno != EINTR)
                return r;
        }
    }   

    static size_t fread_eintr(char *data, size_t size, FILE *f) {
        errno = 0;
        while(true) {
            const size_t r = fread(data, 1, size, f); 
            if(r == size || errno != EINTR)
                return r;
        }
    }   

    static size_t fseek_eintr(FILE *f, long offset, int whence) {
        errno = 0;
        while(true) {
            const int r = fseek(f, offset, whence);
            if(r == 0 || errno != EINTR)
                return r;
        }
    }

    Path get_home_dir()
    {
        const char *homeDir = getenv("HOME");
        if(!homeDir)
        {
            passwd *pw = getpwuid(getuid());
            homeDir = pw->pw_dir;
        }
        if(!homeDir) {
            show_notification("QuickMedia", "Failed to get home directory of user", Urgency::CRITICAL);
            abort();
        }
        return homeDir;
    }

    static Path xdg_config_home;
    static Path xdg_cache_home;

    Path get_storage_dir() {
        if(xdg_config_home.data.empty()) {
            const char *xdg_config_home_p = getenv("XDG_CONFIG_HOME");
            if(xdg_config_home_p)
                xdg_config_home = xdg_config_home_p;
            else
                xdg_config_home = get_home_dir().join(".config");
        }

        Path storage_dir = xdg_config_home;
        storage_dir.join("quickmedia");
        return storage_dir;
    }

    Path get_cache_dir() {
        if(xdg_cache_home.data.empty()) {
            const char *xdg_cache_home_p = getenv("XDG_CACHE_HOME");
            if(xdg_cache_home_p)
                xdg_cache_home = xdg_cache_home_p;
            else
                xdg_cache_home = get_home_dir().join(".cache");
        }

        Path cache_dir = xdg_cache_home;
        cache_dir.join("quickmedia");
        return cache_dir;
    }

    int get_cookies_filepath(Path &path, const std::string &plugin_name) {
        Path cookies_dir = get_storage_dir().join("cookies");
        int res = create_directory_recursive(cookies_dir);
        if(res != 0)
            return res;
        path = cookies_dir;
        path.join(plugin_name).append(".txt");
        return 0;
    }

    int create_directory_recursive(const Path &path) {
        size_t index = 0;
        while(true) {
            index = path.data.find('/', index);
            
            // Skips first '/', we don't want to try and create the root directory
            if(index == 0) {
                ++index;
                continue;
            }

            std::string path_component = path.data.substr(0, index);
            int err = makedir(path_component.c_str());
            
            if(err == -1 && errno != EEXIST)
                return err;

            if(index == std::string::npos)
                break;
            else
                ++index;
        }
        return 0;
    }

    FileType get_file_type(const Path &path) {
        struct stat file_stat;
        memset(&file_stat, 0, sizeof(file_stat));
        int ret;
        EINTR_RETRY(ret, stat(path.data.c_str(), &file_stat));
        if(ret == 0)
            return S_ISREG(file_stat.st_mode) ? FileType::REGULAR : FileType::DIRECTORY;
        return FileType::FILE_NOT_FOUND;
    }

    int file_get_content(const Path &path, std::string &result) {
        FILE *file = fopen_eintr(path.data.c_str(), "rb");
        if(!file)
            return -errno;

        int fd = fileno(file);
        struct stat s;
        if(fstat(fd, &s) == -1 || !S_ISREG(s.st_mode)) {
            fclose(file);
            return -1;
        }
        
        fseek_eintr(file, 0, SEEK_END);
        long file_size = ftell(file);
        if(file_size == -1) {
            fprintf(stderr, "Error: attempted to read directory %s as a file\n", path.data.c_str());
            fclose(file);
            return -1;
        }
        fseek_eintr(file, 0, SEEK_SET);

        result.resize(file_size);
        if(fread_eintr(&result[0], file_size, file) != (size_t)file_size) {
            fclose(file);
            return -1;
        }

        fclose(file);
        return 0;
    }

    int file_get_size(const Path &path, int64_t *size) {
        struct stat64 file_stat;
        memset(&file_stat, 0, sizeof(file_stat));
        int ret;
        EINTR_RETRY(ret, stat64(path.data.c_str(), &file_stat));
        if(ret == 0 && S_ISREG(file_stat.st_mode)) {
            *size = file_stat.st_size;
            return 0;
        }
        *size = 0;
        return -1;
    }

    bool file_get_last_modified_time_seconds(const char *path, time_t *result) {
        struct stat file_stat;
        memset(&file_stat, 0, sizeof(file_stat));
        int ret;
        EINTR_RETRY(ret, stat(path, &file_stat));
        if(ret == 0) {
            *result = file_stat.st_mtim.tv_sec;
            return true;
        }
        return false;
    }

    static int file_overwrite(const Path &path, const char *str, size_t size) {
        FILE *file = fopen_eintr(path.data.c_str(), "wb");
        if(!file) {
            perror(path.data.c_str());
            return -1;
        }
        
        if(fwrite_eintr(str, size, file) != size) {
            fclose(file);
            return -1;
        }

        return fclose(file);
    }

    int file_overwrite(const Path &path, const std::string &data) {
        return file_overwrite(path, data.c_str(), data.size());
    }

    int file_overwrite_atomic(const Path &path, const std::string &data) {
        Path tmp_path = path;
        tmp_path.append(".tmp");
        int res = file_overwrite(tmp_path, data.c_str(), data.size());
        if(res != 0)
            return res;
        return rename_atomic(tmp_path.data.c_str(), path.data.c_str());
    }

    bool file_append(const Path &path, const std::string &data) {
        FILE *file = fopen_eintr(path.data.c_str(), "ab");
        if(!file) {
            perror(path.data.c_str());
            return false;
        }

        if(fwrite_eintr(data.data(), data.size(), file) != data.size()) {
            fclose(file);
            return false;
        }

        return fclose(file) == 0;
    }

    void for_files_in_dir(const Path &path, FileIteratorCallback callback) {
        try {
            for(auto &p : std::filesystem::directory_iterator(path.data)) {
                std::error_code ec;
                const FileType file_type = p.is_directory(ec) ? FileType::DIRECTORY : FileType::REGULAR;
                if(!callback(p.path().string(), file_type, 0))
                    break;
            }
        } catch(const std::filesystem::filesystem_error &err) {
            fprintf(stderr, "Failed to list files in directory %s, error: %s\n", path.data.c_str(), err.what());
            return;
        }
    }

    void for_files_in_dir_sort_last_modified(const Path &path, FileIteratorCallback callback, FileSortDirection sort_dir) {
        std::vector<std::pair<std::filesystem::directory_entry, time_t>> paths_with_last_modified;
        try {
            for(auto &p : std::filesystem::directory_iterator(path.data)) {
                time_t last_modified = 0;
                file_get_last_modified_time_seconds(p.path().c_str(), &last_modified);
                paths_with_last_modified.push_back(std::make_pair(p, last_modified));
            }
        } catch(const std::filesystem::filesystem_error &err) {
            fprintf(stderr, "Failed to list files in directory %s, error: %s\n", path.data.c_str(), err.what());
            return;
        }

        if(sort_dir == FileSortDirection::ASC) {
            std::sort(paths_with_last_modified.begin(), paths_with_last_modified.end(), [](const auto &path1, const auto &path2) {
                return path1.second > path2.second;
            });
        } else {
            std::sort(paths_with_last_modified.begin(), paths_with_last_modified.end(), [](const auto &path1, const auto &path2) {
                return path1.second < path2.second;
            });
        }

        for(auto &p : paths_with_last_modified) {
            std::error_code ec;
            const FileType file_type = p.first.is_directory(ec) ? FileType::DIRECTORY : FileType::REGULAR;
            if(!callback(p.first.path().string(), file_type, p.second))
                break;
        }
    }

    void for_files_in_dir_sort_name(const Path &path, FileIteratorCallback callback, FileSortDirection sort_dir) {
        std::vector<std::filesystem::directory_entry> paths;
        try {
            for(auto &p : std::filesystem::directory_iterator(path.data)) {
                paths.push_back(p);
            }
        } catch(const std::filesystem::filesystem_error &err) {
            fprintf(stderr, "Failed to list files in directory %s, error: %s\n", path.data.c_str(), err.what());
            return;
        }

        if(sort_dir == FileSortDirection::ASC) {
            std::sort(paths.begin(), paths.end(), [](const std::filesystem::directory_entry &path1, std::filesystem::directory_entry &path2) {
                return path1.path().filename() < path2.path().filename();
            });
        } else {
            std::sort(paths.begin(), paths.end(), [](const std::filesystem::directory_entry &path1, std::filesystem::directory_entry &path2) {
                return path1.path().filename() > path2.path().filename();
            });
        }

        for(auto &p : paths) {
            std::error_code ec;
            const FileType file_type = p.is_directory(ec) ? FileType::DIRECTORY : FileType::REGULAR;
            if(!callback(p.path().string(), file_type, 0))
                break;
        }
    }

    bool read_file_as_json(const Path &filepath, Json::Value &result) {
        std::string file_content;
        if(file_get_content(filepath, file_content) != 0) {
            //fprintf(stderr, "Failed to get content of file: %s\n", filepath.data.c_str());
            return false;
        }

        Json::CharReaderBuilder json_builder;
        std::unique_ptr<Json::CharReader> json_reader(json_builder.newCharReader());
        std::string json_errors;
        if(!json_reader->parse(file_content.data(), file_content.data() + file_content.size(), &result, &json_errors)) {
            fprintf(stderr, "Failed to read file %s as json, error: %s\n", filepath.data.c_str(), json_errors.c_str());
            return false;
        }

        return true;
    }

    bool save_json_to_file_atomic(const Path &path, const Json::Value &json) {
        Json::StreamWriterBuilder json_builder;
        return file_overwrite_atomic(path, Json::writeString(json_builder, json)) == 0;
    }

    bool save_json_to_file_atomic(const Path &path, const rapidjson::Value &json) {
        Path tmp_path = path;
        tmp_path.append(".tmp");

        rapidjson::StringBuffer buffer;
        rapidjson::Writer<rapidjson::StringBuffer> writer(buffer);
        json.Accept(writer);

        if(file_overwrite(tmp_path, buffer.GetString(), buffer.GetSize()) != 0)
            return false;

        return rename_atomic(tmp_path.data.c_str(), path.data.c_str()) == 0;
    }

    int rename_atomic(const char *oldpath, const char *newpath) {
        int fd = open(oldpath, O_RDONLY);
        if(fd == -1) {
            perror(oldpath);
            return -1;
        }

        if(fsync(fd) == -1) {
            perror(oldpath);
            close(fd);
            return -1;
        }

        close(fd);
        return rename(oldpath, newpath);
    }

    bool is_program_executable_by_name(const char *name) {
        char *env = getenv("PATH");
        if(!env)
            return false;

        std::unordered_set<std::string> paths;
        string_split(env, ':', [&paths](const char *str, size_t size) {
            if(size > 0)
                paths.insert(std::string(str, size));
            return true;
        });

        for(const std::string &path_str : paths) {
            Path path(path_str);
            path.join(name);
            if(get_file_type(path) == FileType::REGULAR)
                return true;
        }

        return false;
    }

    std::string file_size_to_human_readable_string(int64_t bytes) {
        double kb = (double)bytes / 1024.0;
        double mb = (double)bytes / 1024.0 / 1024.0;
        double gb = (double)bytes / 1024.0 / 1024.0 / 1024.0;
        char result[32];

        if(gb >= 1.0)
            snprintf(result, sizeof(result), "%.1f GiB", gb);
        else if(mb >= 1.0)
            snprintf(result, sizeof(result), "%.1f MiB", mb);
        else if(kb >= 1.0)
            snprintf(result, sizeof(result), "%.1f KiB", kb);
        else
            snprintf(result, sizeof(result), "%zu bytes", bytes);

        return result;
    }
}