#include <filesystem>
#include <fstream>
#include <chrono>
#include <format>
#include <nlohmann/json.hpp>
#include <iostream>
#include <sstream>
#include <deque>
#include <vector>
#include <cctype>
#include "appinfo.h"
#include "executionmanager.h"
#include "log.h"

extern "C" {
#include <sys/types.h>
#include <pwd.h>
#include <unistd.h>
#include <cstdlib>
}

char *get_current_time() {
    const auto now = std::chrono::system_clock::now();
    const std::time_t t_c = std::chrono::system_clock::to_time_t(now);
    return std::ctime(&t_c);
}

struct Options {
    std::string json_file_path = "";
    std::string log_directory = "";
    long long int log_file_max_size = 10 * 1024 * 1024;
    int threads = 16;
    bool check_for_errors = false;
public:
    Options() {
        const char *home = std::getenv("HOME");
        if(!home || strlen(home) <= 0)
        {
            log_directory = "StartUpApps/logs";
            return;
        }
        using fp = std::filesystem::path;
        fp fs = fp(home) / ".local" / "share" / "StartUpApps" / "logs";
        log_directory = fs.string();
    }
}options;

void createConfig() {
    using json = nlohmann::json;
    json config;
    config["log_file_max_size"] = 10 * 1024 * 1024;
    std::string str = config.dump();
    std::fstream file_out("config.json", std::fstream::out);
    file_out << str;
    file_out.flush();
    file_out.close();
}

void parseConfig() {
    using json = nlohmann::json;
    if(!std::filesystem::exists("config.json")) {
        std::cout  << "No config file creating one." << std::endl;
        createConfig();
    }
    std::fstream file_in("config.json", std::fstream::in);
    std::stringstream ss;
    char data;
    while(!file_in.eof()) {
        file_in.get(data);
        if(file_in.eof())
            break;
        ss << data;
    }
    json config = json::parse(ss.str());
    if(config.find("log_file_max_size") != config.end() && config["log_file_max_size"].is_number_integer()) {
        options.log_file_max_size = config["log_file_max_size"].get<long long int>();
    }
}

std::string strip(std::string& t) {
    std::string g;
    for(auto i: t) {
        if(i == ' ' || i == '\t' || i == '\n' || i == '\v' || i == '\r')
            continue;
        else
            g += i;
    }
    return g;
}

void printHelp() {
    std::cout << R"(Usage: StartUpRunner [OPTIONS]
OPTIONS:
    --help|-h               : Prints this screen.
    --version|-v            : Prints version info.
    --threads|-t  [T]       : Sets number of threads to [T].
    --log_dir|-ld [Dir]     : Sets log directory to [Dir].
    --defaults|-d           : Prints the default values used if no arguments are provided.
    --json|-j     [FileName]: Set Json Startup List to FileName.
    --test|-T     [FileName]: Check the json file for errors.
For a detailed info about the json startup file use --help json.)" << std::endl;
}

void printVersion() {
    std::cout << "StartUpRunner: Version-0.0.3 Pre-Alpha Pre-BigBang Era Edition." << std::endl;
}

void printDefaults() {
    std::cout << "StartUpRunner Default Values: " << std::endl;
    std::cout << "Json file        : " << options.json_file_path << std::endl;
    std::cout << "Logs directory   : " << options.log_directory << std::endl;
    std::cout << "Log file max size: " << options.threads << std::endl;
    std::cout << "Threads          : " << options.threads << std::endl;
}

void printJsonHelp() {
    std::cout << R"(Json StartUp List file format:
Top level is an Array of Apps.
Each App Entry contains:
    [REQUIRED] name[string]           : Name of the module.
    [REQUIRED] app_name[string]       : Path to the program with its name.
    [REQUIRED] run_mode[string]       : Mode can be daemon or script.
    [OPTIONAL] app_args[list[string]] : List of arguments to the program.
        Mode daemon   : The app forks the program and exits without waiting.
        Mode script   : The app forks the program and waits for it to finish execution.
                        If no run_mode is given it is presumed to be script.
    [OPTIONAL] after[{name,state}]    : List containing names and state of modules.
        name[string] : Name of the other module.
        state[string]: State of the other module.
            State exited  : Specified module must have finished execution.
            State running : Specified module must be running.
        This module will be launched after the module foundin this list using name is at the state specified as state.
    [OPTIONAL] env{key: value}        : Additional enviroment variables.
        Every key in this object will be used as environment name,
        and every corresponding value as its value.
    [OPTIONAL] working_dir[string]    : Working directory of the program.
    [OPTIONAL] create_log[boolean]    : Create a log file at logs path.
    [OPTIONAL] run_as[string]         : Run as a particular user.
    [OPTIONAL] run_every[string]      : Run task at every specified interval.
        format should be like:
        [digits][unit]
        valid units are:
        s or S: seconds
        m: minutes
        h or H: hours
        d or D: days
        w or W: weeks
        M: months
        Example: 15s
        Example: 2h
    [OPTIONAL] run_at[string]         : Run task at every specified time.
        Format of string should be like:
        "[time] Daily": for running daily at that time
        "[day] [time] Weekly": for running every week on those days at that time.
        "[day_month] [time] Monthly": for running every month on those days at that time.
        [time] format is 24Hrs with [HH:MM:SS]
        [day] format is any of [Mon, Tue, Wed, Thu, Fri, Sat, Sun]
        [day_month] format is 1-31.
        For Weekly, [day] can be a list of days seperated by commas.
        For Monthly, [day_month] can be a list of days seperated by commas.
        For Any, [time] can be a list of timestamps seperated by commas.
        [time] Daily: for running daily at that time.
        [day] [time] Weekly: for running every week on those days at that time.
    [OPTIONAL] run_on_start[boolean]  : Run on initial startup as well [Only valid for scheduled tasks].

Example startup_apps.json:
[
  {
    "name": "LS 0",
    "app_name": "/bin/ls",
    "app_args": ["-l"],
    "run_mode": "script",
    "create_log": true,
    "working_dir": "/home/"
  },
  {
    "name": "LS 1",
    "app_name": "/bin/ls",
    "app_args": ["-l"],
    "run_mode": "script",
    "create_log": true,
    "after": [{"module": "LS 0", "state": "exited"}],
    "env": {"PATH": "/home/:/usr/bin/", "NAME": "ONE"},
    "working_dir": "/home/etc",
    "run_as": "username",
    "run_every": "10s",
    "run_on_start": true
  },
  {
    "name": "LS 2",
    "app_name": "/bin/ls",
    "app_arpgs": ["-lh"],
    "run_mode": "script",
    "create_log": true,
    "after": [{"module": "LS 0", "state": "exited"}],
    "working_dir": "/home/etc/Documents",
    "run_on_start": false,
    "run_at": "1,15,30 01:30:00 Monthly"
  }
]
)";

}

int contains(std::vector<std::string> &list, std::string l, std::string v) {
    for(int i = 0; i < list.size(); i++) {
        if(list[i] == l || list[i] == v)
            return i;
    }
    return -1;
}

int toint(std::string s) {
    std::stringstream ss;
    int ret;
    ss << s;
    ss >> ret;
    return ret;
}

void parseArgs(int c, char *v[]) {
    if(c == 1)
        return;
    if(c == 2) {
        std::string arg1(v[1]);
        if(arg1 == "--help" || arg1 == "-h") {
            printHelp();
            exit(0);
        }
        if(arg1 == "--version" || arg1 == "-v") {
            printVersion();
            exit(0);
        }
        if(arg1 == "--defaults" || arg1 == "-d") {
            printDefaults();
            exit(0);
        }

    }
    if(c >= 2) {
        std::vector<std::string> arg_list;
        for(int i=1; i<c; i++) {
            arg_list.push_back(v[i]);
        }
        bool contains_any_known_arg = false;
        int i = contains(arg_list, "--json", "-j");
        if(i >= 0) {
            int j = i + 1;
            if(j > arg_list.size()) {
                printHelp();
                exit(-1);
            }
            options.json_file_path = arg_list[j];
            std::cout << "Json file path: " << options.json_file_path << std::endl;
            contains_any_known_arg = true;
        }
        i = contains(arg_list, "--log_dir", "-ld");
        if(i >= 0) {
            int j = i + 1;
            if(j > arg_list.size()) {
                printHelp();
                exit(-1);
            }
            options.log_directory = arg_list[j];
            std::cout << "Log directory: " << options.log_directory << std::endl;
            contains_any_known_arg = true;
        }
        i = contains(arg_list, "--threads", "-t");
        if(i >= 0) {
            int j = i + 1;
            if(j > arg_list.size()) {
                printHelp();
                exit(-1);
            }
            options.threads = toint(arg_list[j]);
            std::cout << "Threads: " << options.threads << std::endl;
            contains_any_known_arg = true;
        }
        i = contains(arg_list, "--test", "-T");
        if(i >= 0) {
            int j = i + 1;
            if(j > arg_list.size()) {
                printHelp();
                exit(-1);
            }
            options.check_for_errors = true;
            std::cout << "Testing json file." << std::endl;
            contains_any_known_arg = true;
        }
        i = contains(arg_list, "--help", "-h");
        if(i >= 0) {
            int j = i + 1;
            if(j > arg_list.size()) {
                printHelp();
                exit(-1);
            }
            if(arg_list[j] == "json") {
                printJsonHelp();
                exit(0);
            }
            else {
                printHelp();
                exit(-1);
            }
            contains_any_known_arg = true;
        }
        if(!contains_any_known_arg) {
            printHelp();
            exit(-1);
        }
    }
}

std::string string_strip(std::string str) {
    std::string ch;
    bool front_found = false;
    for(int i=0; i<str.size(); i++) {
        if(!front_found) {
            if(str[i] == ' ' || str[i] == '\t' || str[i] == '\n' || str[i] == '\v' || str[i] == '\r')
                continue;
            else {
                front_found = true;
                ch += str[i];
                continue;
            }
        }
        else
            ch += str[i];
    }
    auto pos = ch.find_last_not_of(" \t\n\v\r");
    if(pos == std::string::npos)
        return ch;
    ch.erase(pos+1);
    return ch;
}

std::vector<std::string> string_split(std::string s, const std::string& delimiter) {
    std::vector<std::string> tokens;
    size_t pos = 0;
    std::string token;
    while ((pos = s.find(delimiter)) != std::string::npos) {
        token = s.substr(0, pos);
        tokens.push_back(token);
        s.erase(0, pos + delimiter.length());
    }
    tokens.push_back(string_strip(s));
    return tokens;
}

std::string tolower(std::string str) {
    std::string s;
    std::transform(str.begin(), str.end(), std::back_inserter(s), [](char c){
        return std::tolower(c);
    });
    return s;
}

void printListModules(const std::vector<std::shared_ptr<AppInfo>>& item_list, std::ostream &out) {
    std::stringstream ss;
    int s = item_list.size();
    ss << "List Contains --> ";
    for(auto &i: item_list) {
        s--;
        if(s > 0)
            ss << i->getModuleName() << ", ";
        else
            ss << i->getModuleName();
    }
    out << ss.str() << std::endl;
}

bool listContainsAfter(const std::vector<std::shared_ptr<AppInfo>> &list, const AppInfo::AppData &item) {
    std::map<std::string, bool> contains_list;
    std::string it = item.getAfterKeys();
    auto string_list = string_split(it, ",");
    for(auto &i: string_list) {
        bool found = false;
        for(auto &j: list) {
            if(tolower(string_strip(j->getModuleName())) == tolower(string_strip(i))) {
                contains_list[i] = true;
                found = true;
                break;
            }
        }
        if(!found)
            contains_list[i] = false;
    }



    bool value = std::all_of(contains_list.begin(), contains_list.end(),
            [](const auto &it) {
                return it.second;
    });
    return value;
}

std::optional<int> checkAppList(std::deque<AppInfo::AppData> &copy_list, std::vector<std::shared_ptr<AppInfo>> &after_list, std::ostream &out) {
    out << "Checking app list with: " << copy_list.size() << " apps for errors..." << std::endl;
    int reshuffle_count = 0;
    while(copy_list.size() != 0) {
        size_t copy_list_size = copy_list.size();
        for(auto item = copy_list.begin(); item != copy_list.end();) {
            if(item->after.size() == 0) {
                std::shared_ptr<AppInfo> app_info = std::make_shared<AppInfo>();
                app_info->copyFromData(*item);
                after_list.push_back(std::move(app_info));
                out << "Module has no dependency: " << item->module_name << std::endl;
                reshuffle_count = 0;
                item = copy_list.erase(item);
            }
            else if(listContainsAfter(after_list, *item)) {
                out << "Module: "  << item->module_name <<
                    " has dependency: " << item->getAfterString() << " and it was found." << std::endl;

                std::shared_ptr<AppInfo> app_info = std::make_shared<AppInfo>();
                app_info->copyFromData(*item);

                for(auto &[key, value]: item->after) {
                    bool found = false;
                    for(int i=0;i<after_list.size();i++) {
                        if(tolower(string_strip(after_list[i]->getModuleName())) == tolower(string_strip(key))) {
                            if(value == "running") {
                                app_info->insertParent(after_list[i], AppInfo::State::running);
                            }
                            else if(value == "exited") {
                                app_info->insertParent(after_list[i], AppInfo::State::exited);
                            }
                            else {
                                out << "Unknown state for: " << item->module_name <<
                                    "'s dependency of: " << after_list[i]->getModuleName() << std::endl;
                                return std::nullopt;
                            }
                            found = true;
                            break;
                        }
                    }
                    if(!found) {
                        out << "Depenedency not found" << std::endl;
                    }
                }
                after_list.push_back(std::move(app_info));
                reshuffle_count = 0;
                item = copy_list.erase(item);
            }
            else {
                item++;
            }
            if(copy_list.size() == 0 || item == copy_list.end())
                break;
        }
        if(copy_list.size() == copy_list_size) {
            reshuffle_count++;
            if(reshuffle_count >= 3) {
                out << "List contains cyclic dependency or unresolvable dependency..." << std::endl;
                out << "Affected apps in list: " << std::endl;
                for(auto &i: copy_list) {
                    i.printInfo(out);
                }
                std::cout << "Resolved list order: " << std::endl;
                printListModules(after_list, out);
                return std::nullopt;
            }
        }
    }
    for(auto &i: after_list) {
        bool run_validity = i->checkValidity();
        i->printInfo(out);
        for(auto &[j, state]: i->getParents()) {
            if(state == AppInfo::State::exited && j->getRunMode() == AppInfo::RunMode::daemon) {
                out << "[WARN]: " << i->getModuleName() <<
                    " is waiting for a daemon: " << j->getModuleName() << " to start exeuction." <<
                    std::endl;
            }
        }
        if(!run_validity) {
            out << "[ERR]: " << i->getModuleName() <<
                " incorrect format for scheduled run. Please see help page." << std::endl;
        } else if((i->getScheduled()) && (!i->getRunOnStart())) {
            const auto* zone = std::chrono::current_zone();
            auto local_now = zone->to_local(i->getNextTimeToRun());
            out << "Module: " << i->getModuleName() <<
                " is scheduled for execution at: " <<
                std::format("{:%F %T}", local_now) << std::endl;
        } else if((i->getScheduled()) && (i->getRunOnStart())) {
            const auto* zone = std::chrono::current_zone();
            auto local_now = zone->to_local(i->getNextTimeToRun());
            out << "Module: " << i->getModuleName() <<
                " will run on init and is also scheduled for execution at: " <<
                std::format("{:%F %T}", local_now) << std::endl;
        }
        else {
            out << "Module: " << i->getModuleName() <<
                " is to be launched on init." << i->getScheduled() << i->getRunOnStart() << run_validity << std::endl;
        }
    }
    return 0;
}

int main(int argc, char *argv[]) {
    parseConfig();
    parseArgs(argc, argv);
    if(!std::filesystem::exists(options.log_directory)) {
        std::filesystem::create_directories(options.log_directory);
    }
    std::filesystem::path json_path = options.json_file_path;
    std::string log_file_path = std::filesystem::path(options.log_directory) / "StartUpRunner.log";
    Log log_file(log_file_path, options.log_file_max_size);
    std::cout << "Starter Init: Log file path: " << log_file_path << std::endl;
    std::cout << "Log file open: " << log_file.isOpen() << std::endl;
    log_file << "-------- Starting app --------" << std::endl;
    log_file << "Current Time: " << get_current_time();
    log_file << "Log file max size: " << options.log_file_max_size << std::endl;
    log_file << "Current path: " << std::filesystem::current_path() << std::endl;
    std::string json_file_path = json_path;
    if(std::filesystem::is_directory(json_path)) {
        json_file_path = json_path / "startup_apps.json";
    }
    else if(json_path == "") {
        json_file_path = "startup_apps.json";
    }
    if(!std::filesystem::exists(json_file_path)) {
        log_file << std::vformat("startup_apps.json not found exiting at: {}.\n", std::make_format_args(json_file_path));
        exit(-1);
    }
    else {
        log_file << "startup_apps.json loaded from: " << json_file_path << std::endl;
    }
    std::string data = "";
    std::string t_data = "";
    std::fstream json_file;
    json_file.open(json_file_path, std::fstream::in);
    if(!json_file.is_open()) {
        log_file << "Why is the startup_apps.json file not open?" << std::endl;
        std::cerr << "startup_apps.json file is not readable from location: " << json_file_path << "." << std::endl;
        return -1;
    }
    std::stringstream test;
    test << json_file.rdbuf();
    json_file.close();
    using json = nlohmann::json;
    bool valid = json::accept(test.str());
    if(!valid) {
        log_file << "Json Document Parsing error...." << std::endl;
        std::cerr << "Invalid JSON format in: " << json_file_path << "." << std::endl;
        return -1;
    }
    json file = json::parse(test.str());
    std::deque<AppInfo::AppData> initial_app_list;
    for(auto i = file.begin(); i != file.end(); i++) {
        AppInfo::AppData app_info;
        auto object = i->get<json>();
        if(object.find("app_name") == object.end()) {
            log_file << "Error in json." << std::endl;
            log_file << "Field app name is a required field." << std::endl;
            std::cerr << "Field error in: " << json_file_path << ", check log for more details." << std::endl;
            exit(-2);
        }
        if(object.find("name") == object.end()) {
            log_file << "Error in json." << std::endl;
            log_file << "Field name is a required field." << std::endl;
            std::cerr << "Field error in: " << json_file_path << ", check log for more details." << std::endl;
            exit(-2);
        }
        if(object.find("run_mode") == object.end()) {
            log_file << "Error in json." << std::endl;
            log_file << "Field run_mode is a required field." << std::endl;
            std::cerr << "Field error in: " << json_file_path << ", check log for more details." << std::endl;
            exit(-2);
        }
        app_info.program_name = object["app_name"].get<std::string>();
        std::string args = "";
        std::deque<const char*> c_args;
        std::deque<std::string> arg_list;
        if(object.find("app_args") != object.end()) {
            for(const auto &k: object["app_args"].get<json>()) {
                std::string str = k.get<std::string>();
                args += str + " ";
                arg_list.push_back(str);
                c_args.push_back(str.c_str());
            }
        }
        std::unordered_map<std::string, std::string> after_list;
        std::unordered_map<std::string, std::string> env_list;
        if(object.find("after") != object.end()) {
            for(const auto &k: object["after"].get<json>()) {
                auto l = k.get<json>();
                auto key = l["module"].get<std::string>();
                auto value = l["state"].get<std::string>();
                after_list[key] = value;
            }
        }
        if(object.find("env") != object.end()) {
            json k = object["env"].get<json>();
            for (auto &it: k.items()) {
                env_list[it.key()] = it.value();
            }
        }
        app_info.args = arg_list;
        if(object.find("working_dir") != object.end())
            app_info.working_dir = object["working_dir"].get<std::string>();
        if(object.find("create_log") != object.end())
            app_info.create_log = object["create_log"].get<bool>();
        if(object.find("run_as") != object.end())
            app_info.run_as = object["run_as"].get<std::string>();
        if(object.find("run_at") != object.end())
            app_info.run_at = object["run_at"].get<std::string>();
        if(object.find("run_every") != object.end())
            app_info.run_every = object["run_every"].get<std::string>();
        if(object.find("run_on_start") != object.end())
            app_info.run_on_start = object["run_on_start"].get<bool>();

        app_info.env = env_list;
        app_info.after = after_list;
        app_info.module_name = object["name"].get<std::string>();
        app_info.run_mode = object["run_mode"].get<std::string>();
        app_info.printInfo(log_file.rdbuf());
        initial_app_list.push_back(app_info);
    }
    std::vector<std::shared_ptr<AppInfo>> list;
    log_file << "Checking App List for errors." << std::endl;
    std::optional<int> list_check;
    if(options.check_for_errors)
        list_check = checkAppList(initial_app_list, list, std::cerr);
    else
        list_check = checkAppList(initial_app_list, list, log_file.rdbuf());
    if(list_check.has_value()) {
        log_file << "No errors found in app list." << std::endl;
    }
    else {
        std::cerr << "Dependency error in: " << json_file_path << "check log for more details." << std::endl;
        log_file << "Errors present in app list; Please fix them" << std::endl;
        return -1;
    }
    if(options.check_for_errors)
        return 0;
    for(int i=0;i<list.size();i++) {
        list[i]->printInfo(log_file.rdbuf());
    }
    log_file << "Order of Execution -> " << std::endl;
    printListModules(list, log_file.rdbuf());
    ExecutionManager manager{options.threads};
    manager.setLogFile(log_file);
    manager.setLogFileMaxSize(options.log_file_max_size);
    manager.setLogDirectoy(options.log_directory);
    manager.setJobs(list);
    manager.run();
    return 0;
}