miner_schedule/task_manager.hpp

#ifndef TASK_MANAGER_HPP
#define TASK_MANAGER_HPP

#include <iostream>
#include <sstream> 
#include <string>
#include <chrono>
#include <thread>
#include <functional>
#include <croncpp.h>
#include "easylogging++.h"

using callable = std::function<void (int pin, int value)>;

enum TaskAction {
    TASK_ACTION_LOW = 0,
    TASK_ACTION_HIGH = 1,
    TASK_ACTION_NONE
};

class Task {
private:
    cron::cronexpr cronexpr;
    TaskAction action;
    callable action_fn;
    int pin;
public:
    Task(cron::cronexpr cronexpr, std::string command, callable action_fn);
    Task(Task &task);
    void doAction();
    std::time_t next();

    friend std::ostream& operator<< (std::ostream &out, const Task &task);
};

class TaskManager {
private:
    std::map<std::time_t, Task> tasks;
public:
    TaskManager(std::istream &stream, callable action_fn);

    int doWork();
};

inline TaskManager::TaskManager(std::istream &stream, callable action_fn) {
    std::string line;
    while (std::getline(stream, line).good()) {
        auto fields = cron::utils::split(line, ' ');
        fields.erase(
            std::remove_if(std::begin(fields), std::end(fields),
            [](CRONCPP_STRING_VIEW s) {return s.empty(); }),
            std::end(fields));
        if (fields.size() != 7)
            throw cron::bad_cronexpr("cron expression must have 7 fields");

        std::stringstream schedule;
        for (int i = 0; i < 6; ++i) {
            schedule << fields[i] << ' ';
        }

        auto cron = cron::make_cron(schedule.str());
        std::time_t now = std::time(0);
        std::time_t next = cron::cron_next(cron, now); 

        tasks.emplace(std::piecewise_construct,
            std::forward_as_tuple(next),
            std::forward_as_tuple(cron, fields[6], action_fn));
    }

    LOG(INFO) << "Schedule table:";
    for (const auto& [key, value] : tasks) {
        LOG(INFO) << key << ' ' << value;
    }
}

inline int TaskManager::doWork() {
    auto it = tasks.begin();
    if(it == tasks.end()) return 0;

    std::time_t now = std::time(0);
    std::time_t stop = it->first;

    LOG(DEBUG) << "Will sleep till next action " << stop - now << 's';

    std::this_thread::sleep_for(std::chrono::seconds{stop - now});

    it->second.doAction();
    tasks.emplace(std::piecewise_construct,
        std::forward_as_tuple(it->second.next()),
        std::forward_as_tuple(it->second));
    tasks.erase(it);

    return 0;
}

inline std::ostream& operator<< (std::ostream &out, const Task &task) {
    out << "Action: ";
    switch (task.action)
    {
    case TASK_ACTION_HIGH:
        out << "HIGH";
        break;

    case TASK_ACTION_LOW:
        out << "LOW";
        break;        
    
    default:
        break;
    }
    
    out << " Pin:" << task.pin;
    return out;
}

inline Task::Task(cron::cronexpr cronexpr, std::string command, callable action_fn):
    cronexpr{cronexpr},
    action{TASK_ACTION_NONE},
    pin{0},
    action_fn{action_fn}
{
    if(command.rfind("HIGH", 0) == 0) {
        action = TASK_ACTION_HIGH;
    } else if((command.rfind("LOW", 0) == 0)) {
        action = TASK_ACTION_LOW;
    }

    auto start = command.find('(');
    auto stop = command.find(')');
    if(start == std::string::npos && stop == std::string::npos) {
        throw cron::bad_cronexpr("pin is not set in command");
    }

    LOG(DEBUG) << "pin to parse " << command.substr(start + 1, stop - start - 1);

    pin = std::stoi(command.substr(start + 1, stop - start - 1));
}

inline Task::Task(Task &task):
    cronexpr{task.cronexpr},
    action{task.action},
    action_fn{task.action_fn},
    pin{task.pin}
{}

inline void Task::doAction() {
    if(action == TASK_ACTION_NONE) return;

    action_fn(pin, action);
}

inline std::time_t Task::next() {
    std::time_t now = std::time(0);
    return cron::cron_next(cronexpr, now);
}

#endif //TASK_MANAGER_HPP