#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

typedef struct MemoHistory{
    int lineNumber;
    char command[100];
}MemoHistory;

void AddHistoryData(char command[100]);
bool CheckArgumentSet(int argc, char* argv[], char argumentLetter);
void GetCommandNumber(MemoHistory* historyData, int commandNumber);
int GetHistoryLineCount();
void Memo(int argc, char* argv[]);
FILE* OpenHistoryFile(char* openType);
void PrintHistory();
void RunCommandNumber(char* command);
void TestHistoryData();

int main(int argc, char* argv[])
{
    if (argc == 1)
        PrintHistory();
    if (argc > 1)
        Memo(argc, argv);
    return 0;
}

void AddHistoryData(char command[100])
{
    FILE* historyFile = OpenHistoryFile("a");
    MemoHistory historyData;
    strcpy(historyData.command, command);
    historyData.lineNumber = GetHistoryLineCount() + 1;
    fwrite(&historyData, sizeof(MemoHistory), 1, historyFile);
    return;
}


// Check if an argument is set
// Returns true if found, false if argument not found
bool CheckArgumentSet(int argc, char* argv[], char argumentLetter)
{
    char argumentHyphen = '-';
    for (int i = 1; i < argc; i++)
        if ((*(argv[i]) == argumentHyphen) && (*(argv[i]+1) == argumentLetter))
            return 1;
    return 0;
}

// Get numbered command from memo.history
void GetCommandNumber(MemoHistory* historyData, int commandNumber)
{
    FILE* historyFile = OpenHistoryFile("r");
    while(fread(historyData, sizeof(MemoHistory), 1, historyFile))
        if (historyData->lineNumber == commandNumber)
            break;    
    fclose(historyFile);
    return;
}

// Get the highest line number in the history file and returns it
int GetHistoryLineCount()
{
    FILE* historyFile = OpenHistoryFile("r");
    MemoHistory historyData;
    historyData.lineNumber = 0;
    while(fread(&historyData, sizeof(MemoHistory), 1, historyFile))
        ;
    fclose(historyFile);
    return historyData.lineNumber;
}

// Base Memo function
// Runs command then puts command in memo.history
void Memo(int argc, char* argv[])
{
    if (CheckArgumentSet(argc, argv, 'e'))
    {
        RunCommandNumber(argv[2]);
        return;
    }
    char commandInput[100];
    for (int i = 1; i < argc; i++)
    {
        strcat(commandInput, argv[i]);
        strcat(commandInput, " ");
    }
    system(commandInput);
    AddHistoryData(commandInput);
}

// Safely opens memo.history
// Returns true if successful, false if unsuccessful
FILE* OpenHistoryFile(char* openType)
{
    FILE* historyFile;
    if ((historyFile = fopen("memo.history", openType)) == NULL)
    {
        perror("memo.history");
        exit(EXIT_FAILURE);
    }
    return historyFile;
}

// Prints data from memo.history file
void PrintHistory()
{
    FILE* historyFile = OpenHistoryFile("r");
    MemoHistory historyData;
    while(fread(&historyData, sizeof(MemoHistory), 1, historyFile))
        printf("%2d %s\n", historyData.lineNumber, historyData.command);
    fclose(historyFile);
}

// Run numbered command from memo.history
void RunCommandNumber(char* command)
{
    MemoHistory historyData;
    int commandNumber = 0;
    sscanf(command, "%d", &commandNumber);
    GetCommandNumber(&historyData, commandNumber);
    system(historyData.command);
}

void TestHistoryData()
{
    MemoHistory historyData;
    FILE* historyFile = OpenHistoryFile("w");
    for (int i = 1; i < 11; i++)
    {
        historyData.lineNumber = i;
        strcpy(historyData.command, "echo hello world");
        fwrite(&historyData, sizeof(MemoHistory), 1, historyFile);
    }
    fclose(historyFile);
}