#include <iostream>
#include <fstream>
#include <cstring>
#include <unistd.h>
#include <chrono>
#include <sstream>
#include <string>
#include <bits/stdc++.h>

using namespace std;

struct process_detail {
	//cpu_burst_times[0] is arrival time
	int pid;
	vector<int> burst_times;
	int in_cpu1;
	int in_cpu2;
	int current_burst_index;
};

struct clock{
	int push_signal; //boolean
	int timer;

};

vector<process_detail> processes;
queue<process_detail*> ready_queue_fifo;
vector<process_detail*> waiting;
process_detail* CPU1 = NULL;
process_detail* CPU2 = NULL;

ofstream output_file("cpu_times.txt");

// ------------------------------------- THE FIFO ---------------------------------------
void fifo() {
    // Clock initialized to 0
    struct clock time;
    memset(&time, 0, sizeof(struct clock));
    time.timer = 0;
    time.push_signal = 5;
    int process_count = processes.size();
    int completed_processes = 0;
	string out_string1 = "";
	string out_string2 = "";

    while(completed_processes < process_count) {

        // Breaking from the infinite loop
        for (int i = 0; i < process_count; ++i) {
            if (processes[i].burst_times[processes[i].current_burst_index] == -2) {
                completed_processes++;
            }
        }

        // Managing arrival times
        for (int i = 0; i < process_count; ++i) {
            if(processes[i].in_cpu1 != 1 || processes[i].in_cpu2 != 1) {
				if(time.timer == processes[i].burst_times[0]) {
					ready_queue_fifo.push(&processes[i]);
					processes[i].current_burst_index++;
				}
                
            }			
        }

        // Managing waiting queue
        for (int j = 0; j < waiting.size(); ++j) {
            if (waiting[j] != NULL) {
                if (waiting[j]->burst_times[waiting[j]->current_burst_index] == 0) {
                    ready_queue_fifo.push(waiting[j]);
					waiting[j]->current_burst_index++;
					waiting[j] = NULL;
				}
            }
        }
        
        if (CPU1 == NULL && !ready_queue_fifo.empty()) {
			// Assign the first process from the ready queue to the CPU
			CPU1 = ready_queue_fifo.front();
			CPU1->in_cpu1 = 1;
			// Record in_time when the process enters the CPU
			out_string1 = "P" + to_string(CPU1->pid+1) + ",1 " + to_string(time.timer);
			// output_file << "P" << CPU1->pid + 1 << ",1 " << time.timer;
			ready_queue_fifo.pop();
		}

        if (CPU2 == NULL && !ready_queue_fifo.empty()) {
			// Assign the first process from the ready queue to the CPU
			CPU2 = ready_queue_fifo.front();
			CPU2->in_cpu2 = 1;
			// Record in_time when the process enters the CPU
			// output_file << endl;
			out_string2 = "P" + to_string(CPU2->pid+1) + ",2 " + to_string(time.timer);
			// output_file << "P" << CPU2->pid + 1 << ",2 " << time.timer;
			ready_queue_fifo.pop();
		} 

        // Check CPU1
        if(CPU1 != NULL) {
            //check cpu_burst complete
			for(int i = 0; i < process_count; ++i) {
				if(processes[i].in_cpu1 == 1) {
					if(CPU1->burst_times[processes[i].current_burst_index] == 0){
						// Record out_time when the process exits the CPU
						out_string1 += " " + to_string(time.timer);
						output_file << out_string1 << endl;
                        // output_file << " " << time.timer << endl;
						CPU1->in_cpu1 = 0;
						CPU1->current_burst_index++;
						waiting.push_back(CPU1); // process added to waiting queue
						if(!ready_queue_fifo.empty()) {
							CPU1 = ready_queue_fifo.front(); // process added to CPU
							CPU1->in_cpu1 = 1;
							// output_file << "P" << CPU1->pid+1 << ",1" << " " << time.timer; // New entry time
							out_string1 = "P" + to_string(CPU1->pid+1) + ",1 " + to_string(time.timer);
							ready_queue_fifo.pop();
						}
						else {
							CPU1 = NULL;
						}
					}
				}
			}
        }

		if(CPU2 != NULL) {
			//check cpu_burst complete
			for(int i = 0; i < process_count; ++i) {
				if(processes[i].in_cpu2 == 1) {
					if(CPU2->burst_times[processes[i].current_burst_index] == 0){
						// Record out_time when the process exits the CPU
						out_string2 += " " + to_string(time.timer);
						output_file << out_string2 << endl;
						// output_file << " " << time.timer << endl;
						CPU2->in_cpu2 = 0;
						CPU2->current_burst_index++;
						waiting.push_back(CPU2); // process added to waiting queue
						if(!ready_queue_fifo.empty()) {
							CPU2 = ready_queue_fifo.front(); // process added to CPU
							CPU2->in_cpu2 = 1;
							out_string2 = "P" + to_string(CPU2->pid+1) + ",2 " + to_string(time.timer);
							// output_file << "P" << CPU2->pid+1 << ",2" << " " << time.timer; // New entry time
							ready_queue_fifo.pop();
						}
						else {
							CPU2 = NULL;
						}
					}
				}
			}
		}
		
        if(CPU1 != NULL) {
			CPU1->burst_times[CPU1->current_burst_index]--;
		}

        if(CPU2 != NULL) {
			CPU2->burst_times[CPU2->current_burst_index]--;
		}

		for(int j = 0; j < waiting.size(); ++j) {
			if(waiting[j] != NULL) {
				if(waiting[j]->burst_times[waiting[j]->current_burst_index] != 0) {
					waiting[j]->burst_times[waiting[j]->current_burst_index]--; // reducing the io burst till it reaches 0
				}
			}
		}
        // Increment the timer
        time.timer++;
    }
    output_file.close();
    return;

}

// ----------------------------------------THE Shortest Job First----------------------------------
// Custom comparator for the priority queue
struct Compare {
    bool operator()(process_detail* a, process_detail* b) {
        // Compare the elements in the vector at the given indices
        return a->burst_times[a->current_burst_index] > b->burst_times[b->current_burst_index];
    }
};

priority_queue<process_detail*, vector<process_detail*>, Compare> ready_queue;

void sjf() {
    // Clock initialized to 0
    struct clock time;
    memset(&time, 0, sizeof(struct clock));
    time.timer = 0;
    time.push_signal = 5;
    int process_count = processes.size();
    int completed_processes = 0;
	string out_string1 = "";
	string out_string2 = "";

    while(completed_processes < process_count) {

        // Breaking from the infinite loop
        for (int i = 0; i < process_count; ++i) {
            if (processes[i].burst_times[processes[i].current_burst_index] == -2) {
                completed_processes++;
            }
        }

        // Managing arrival times
        for (int i = 0; i < process_count; ++i) {
            if(processes[i].in_cpu1 != 1 || processes[i].in_cpu2 != 1) {
				if(time.timer == processes[i].burst_times[0]) {
					ready_queue.push(&processes[i]);
					processes[i].current_burst_index++;
				}
                
            }			
        }

        // Managing waiting queue
        for (int j = 0; j < waiting.size(); ++j) {
            if (waiting[j] != NULL) {
                if (waiting[j]->burst_times[waiting[j]->current_burst_index] == 0) {
                    ready_queue.push(waiting[j]);
					waiting[j]->current_burst_index++;
					waiting[j] = NULL;
				}
            }
        }
        
        if (CPU1 == NULL && !ready_queue.empty()) {
			// Assign the first process from the ready queue to the CPU
			CPU1 = ready_queue.top();
			CPU1->in_cpu1 = 1;
			// Record in_time when the process enters the CPU
			out_string1 = "P" + to_string(CPU1->pid+1) + ",1 " + to_string(time.timer);
			// output_file << "P" << CPU1->pid + 1 << ",1 " << time.timer;
			ready_queue.pop();
		}

        if (CPU2 == NULL && !ready_queue.empty()) {
			// Assign the first process from the ready queue to the CPU
			CPU2 = ready_queue.top();
			CPU2->in_cpu2 = 1;
			// Record in_time when the process enters the CPU
			// output_file << endl;
			out_string2 = "P" + to_string(CPU2->pid+1) + ",2 " + to_string(time.timer);
			// output_file << "P" << CPU2->pid + 1 << ",2 " << time.timer;
			ready_queue.pop();
		} 

        // Check CPU1
        if(CPU1 != NULL) {
            //check cpu_burst complete
			for(int i = 0; i < process_count; ++i) {
				if(processes[i].in_cpu1 == 1) {
					if(CPU1->burst_times[processes[i].current_burst_index] == 0){
						// Record out_time when the process exits the CPU
						out_string1 += " " + to_string(time.timer);
						output_file << out_string1 << endl;
                        // output_file << " " << time.timer << endl;
						CPU1->in_cpu1 = 0;
						CPU1->current_burst_index++;
						waiting.push_back(CPU1); // process added to waiting queue
						if(!ready_queue.empty()) {
							CPU1 = ready_queue.top(); // process added to CPU
							CPU1->in_cpu1 = 1;
							// output_file << "P" << CPU1->pid+1 << ",1" << " " << time.timer; // New entry time
							out_string1 = "P" + to_string(CPU1->pid+1) + ",1 " + to_string(time.timer);
							ready_queue.pop();
						}
						else {
							CPU1 = NULL;
						}
					}
				}
			}
        }

		if(CPU2 != NULL) {
			//check cpu_burst complete
			for(int i = 0; i < process_count; ++i) {
				if(processes[i].in_cpu2 == 1) {
					if(CPU2->burst_times[processes[i].current_burst_index] == 0){
						// Record out_time when the process exits the CPU
						out_string2 += " " + to_string(time.timer);
						output_file << out_string2 << endl;
						// output_file << " " << time.timer << endl;
						CPU2->in_cpu2 = 0;
						CPU2->current_burst_index++;
						waiting.push_back(CPU2); // process added to waiting queue
						if(!ready_queue.empty()) {
							CPU2 = ready_queue.top(); // process added to CPU
							CPU2->in_cpu2 = 1;
							out_string2 = "P" + to_string(CPU2->pid+1) + ",2 " + to_string(time.timer);
							// output_file << "P" << CPU2->pid+1 << ",2" << " " << time.timer; // New entry time
							ready_queue.pop();
						}
						else {
							CPU2 = NULL;
						}
					}
				}
			}
		}
		
        if(CPU1 != NULL) {
			CPU1->burst_times[CPU1->current_burst_index]--;
		}

        if(CPU2 != NULL) {
			CPU2->burst_times[CPU2->current_burst_index]--;
		}

		for(int j = 0; j < waiting.size(); ++j) {
			if(waiting[j] != NULL) {
				if(waiting[j]->burst_times[waiting[j]->current_burst_index] != 0) {
					waiting[j]->burst_times[waiting[j]->current_burst_index]--; // reducing the io burst till it reaches 0
				}
			}
		}
        // Increment the timer
        time.timer++;
    }
    output_file.close();
    return;
}

int main(int argc, char **argv) {

    if(argc != 3)
	{
		cout <<"usage: ./scheduler.out <path-to-workload-file> <scheduler_algorithm>\nprovided arguments:\n";
		for(int i = 0; i < argc; i++)
			cout << argv[i] << "\n";
		return -1;
	}

    char *file_to_search_in = argv[1];
	char *scheduler_algorithm = argv[2];

    ifstream file(file_to_search_in, ios::binary);
    // ifstream file("temp.dat", ios::binary);
    string buffer;
    int pid = 0;

    while(getline(file, buffer)) {
		if(buffer[0] == '<'){
			continue;
		}
		istringstream iss(buffer);
		string word;
		struct process_detail pd;
		memset(&pd,0,sizeof(struct process_detail));
		pd.pid = pid++;
		pd.current_burst_index = 0;

		while(iss>>word){
			pd.burst_times.push_back(stoi(word));
		}
		processes.push_back(pd);
    }

	map<string, int> temp;
	temp["fifo"] = 1;
	temp["sjf"] = 2;
	temp["pre_sjf"] = 3;
	temp["rr"] = 4;

	string temp1 = scheduler_algorithm;
	// string temp1 = "fifo";

	switch(temp[temp1]){
		case 1:
			fifo();
			break;
		case 2:
			sjf();
			break;
		// case 3:
		// 	pre_sjf();
		// 	break;
		// case 4:
		// 	round_robin();
		// 	break;
		default:
			cout << "enter fifo or sjf or pre_sjf or rr" << endl;
	}

    return 0;
}