Database-Management-System/DatabaseCliCmd.java at main · joshuapanicker/Database-Management-System · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.*;

public class DatabaseCliCmd extends CliCmd {

    private static Map<String, Database> databases = new HashMap<>();
    private static Map<String, DatabasePersistenceLog> persistenceLogs = new HashMap<>();
    private static Database currentDatabase = null;
    private static DatabasePersistenceLog currentPersistenceLog = null;

    public DatabaseCliCmd() {
        super("db");
    }

    @Override
    public boolean createHandler() throws IOException {
        if (args.isEmpty()) {
            System.out.println("Error: db create requires a database name.");
            return false;
        }
        String dbName = args.get(0);
        if (databases.containsKey(dbName)) {
            System.out.println("Error: database '" + dbName + "' already exists.");
            return false;
        }
        Database db = new Database();
        databases.put(dbName, db);
        DatabasePersistenceLog log = new DatabasePersistenceLog(dbName);
        persistenceLogs.put(dbName, log);
        log.logDbCreate();
        System.out.println("Created database '" + dbName + "'.");
        return true;
    }

    @Override
    public boolean selectHandler() {
        if (args.isEmpty()) {
            System.out.println("Error: db select requires a database name.");
            return false;
        }
        String dbName = args.get(0);
        if (!databases.containsKey(dbName)) {
            System.out.println("Error: database '" + dbName + "' not found.");
            return false;
        }
        Database selected = databases.get(dbName);
        if (currentDatabase != selected) {
            TableCliCmd.clearCurrentTable();
        }
        currentDatabase = selected;
        currentPersistenceLog = persistenceLogs.get(dbName);
        System.out.println("Selected database '" + dbName + "'.");
        return true;
    }

    @Override
    public boolean deleteHandler() throws IOException {
        if (args.isEmpty()) {
            System.out.println("Error: db delete requires a database name.");
            return false;
        }
        String dbName = args.get(0);
        if (!databases.containsKey(dbName)) {
            System.out.println("Error: database '" + dbName + "' not found.");
            return false;
        }
        Database removed = databases.remove(dbName);
        DatabasePersistenceLog removedLog = persistenceLogs.remove(dbName);
        if (removedLog != null) {
            Files.deleteIfExists(Path.of(removedLog.getFilePath()));
        }
        if (currentDatabase == removed) {
            currentDatabase = null;
            currentPersistenceLog = null;
            TableCliCmd.clearCurrentTable();
        }
        System.out.println("Deleted database '" + dbName + "'.");
        return true;
    }

    @Override
    public boolean listHandler() {
        if (databases.isEmpty()) {
            System.out.println("No databases.");
        } else {
            System.out.println("Databases: " + databases.keySet());
        }
        return true;
    }

    @Override
    public boolean helpHandler() {
        System.out.println("=== Database Commands ===");
        System.out.println("db create <name>       - Create a new database");
        System.out.println("db select <name>       - Select a database for table operations");
        System.out.println("db delete <name>       - Delete a database");
        System.out.println("db list                - List all databases");
        System.out.println();
        System.out.println("Examples:");
        System.out.println("  db create mystore");
        System.out.println("  db select mystore");
        System.out.println("  db list");
        System.out.println("  db delete mystore");
        return true;
    }

    public static Database getCurrentDatabase() {
        return currentDatabase;
    }

    public static DatabasePersistenceLog getCurrentPersistenceLog() {
        return currentPersistenceLog;
    }
}