main.c

#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <unistd.h>     
#include <sys/wait.h>   

int main() {
    char input[1024];
    char current_mode[50] = ""; 
    char *subjects[] = {"Chemistry", "Mechanics", "Electronics", "C_Programming"};
    int num_subjects = 4;

    while(1) {
        if (strlen(current_mode) > 0) {
            printf("[%s] study-sh> ", current_mode);
        } else {
            printf("study-sh> ");
        }
        
        if (!fgets(input, 1024, stdin)) break; 
        input[strcspn(input, "\n")] = 0;

        if (strcmp(input, "exit") == 0 || strcmp(input, "sleep") == 0) {
            printf("Shutting down workspace.\n");
            break; 
        }
        
        else if (strcmp(input, "build") == 0) {
            printf("Initializing workspace...\n");
            mkdir("Notes", 0777); 
            
            for (int i = 0; i < num_subjects; i++) {
                char path[100];
                sprintf(path, "Notes/%s", subjects[i]);
                
                if (mkdir(path, 0777) == 0) {
                    printf("Created: %s\n", path);
                } else {
                    printf("Exists:  %s\n", path);
                }
            }
        }
        
        else if (strcmp(input, "help") == 0) {
            printf("\n--- study-sh ---\n");
            printf("  help        : Show commands\n");
            printf("  build       : Initialize workspace folders\n");
            printf("  [subject]   : Enter subject mode (e.g., mechanics)\n");
            printf("  add [note]  : Append a note to the current subject\n");
            printf("  read        : Display notes for the current subject\n");
            printf("  leave       : Exit current subject mode\n");
            printf("  search [word]: Search notes for a specific keyword\n");
            printf("  clear       : Clear the terminal screen\n");
            printf("  cd [dir]    : Change directory\n");
            printf("  exit/sleep  : Shut down\n");
            printf("----------------\n\n");
        }
        
        else if (strcmp(input, "leave") == 0) {
            strcpy(current_mode, ""); 
        }

        else if (strncmp(input, "add ", 4) == 0) {
            if (strlen(current_mode) == 0) {
                printf("Error: No subject mode active.\n");
            } else {
                char *note_text = input + 4; 
                char filepath[200];
                sprintf(filepath, "Notes/%s/notes.txt", current_mode);

                FILE *file = fopen(filepath, "a");
                if (file == NULL) {
                    printf("Error: Could not open %s.\n", filepath);
                } else {
                    fprintf(file, "- %s\n", note_text);
                    fclose(file);
                    printf("Note appended.\n");
                }
            }
        }

        else if (strcmp(input, "read") == 0) {
            if (strlen(current_mode) == 0) {
                printf("Error: No subject mode active.\n");
            } else {
                char filepath[200];
                sprintf(filepath, "Notes/%s/notes.txt", current_mode);

                FILE *file = fopen(filepath, "r");
                if (file == NULL) {
                    printf("Empty: No notes found for %s.\n", current_mode);
                } else {
                    printf("\n--- %s ---\n", current_mode);
                    char line[256];
                    while (fgets(line, sizeof(line), file) != NULL) {
                        printf("%s", line); 
                    }
                    printf("----------------\n\n");
                    fclose(file);
                }
            }
        }

        else if (strcmp(input, "clear") == 0) {
            system("clear");
        }

        else if (strncmp(input, "search ", 7) == 0) {
            if (strlen(current_mode) == 0) {
                printf("Error: No subject mode active.\n");
            } else {
                char *keyword = input + 7; 
                char filepath[200];
                sprintf(filepath, "Notes/%s/notes.txt", current_mode);

                FILE *file = fopen(filepath, "r");
                if (file == NULL) {
                    printf("Empty: No notes found for %s.\n", current_mode);
                } else {
                    printf("\n--- Search Results for '%s' ---\n", keyword);
                    char line[256];
                    int found = 0; 
                    
                    while (fgets(line, sizeof(line), file) != NULL) {
                        if (strstr(line, keyword) != NULL) {
                            printf("%s", line); 
                            found = 1;
                        }
                    }
                    
                    if (found == 0) {
                        printf("No matches found.\n");
                    }
                    printf("----------------\n\n");
                    fclose(file);
                }
            }
        }

        else if (strcmp(input, "chemistry") == 0) strcpy(current_mode, "Chemistry");
        else if (strcmp(input, "mechanics") == 0) strcpy(current_mode, "Mechanics");
        else if (strcmp(input, "electronics") == 0) strcpy(current_mode, "Electronics");
        else if (strcmp(input, "c_programming") == 0) strcpy(current_mode, "C_Programming");
        
        // MOVED: The 'cd' command goes HERE, right before the final else
        else if (strncmp(input, "cd ", 3) == 0) {
            char *target_dir = input + 3; 
            if (chdir(target_dir) != 0) {
                perror("cd failed");
            }
        }

        // FINAL FALLBACK: Ask the OS to handle unknown commands
        else {
            char *args[100];
            int i = 0;
            
            args[i] = strtok(input, " "); 
            while (args[i] != NULL) {
                i++;
                args[i] = strtok(NULL, " ");
            }

            pid_t pid = fork();

            if (pid == 0) {
                if (execvp(args[0], args) == -1) {
                    printf("Command not found: %s\n", args[0]);
                }
                exit(1); 
            } 
            else if (pid > 0) {
                wait(NULL); 
            } 
            else {
                printf("Error: Process cloning failed.\n");
            }
        }
    }

    return 0;
}