public class Database {

	public string feeds_table = "feeds";
	public string items_table = "items";
	public struct Field {
		string name;
		string val;
	}
	private Sqlite.Database db;
	private string db_name = "speedyrss";
	
	public Database() {
		int rc;
		
		rc = Sqlite.Database.open(this.db_name + ".db", out this.db);
	
		if (rc != Sqlite.OK) {
			stderr.printf("Cannot open database: %d, %s", rc, db.errmsg ());
		}
	}
	
	public void insert(string table, Field[] fields) {
	
		string query = "INSERT INTO " + table + " (";
		
		foreach (Field data in fields) {
			query += data.name + ", ";
		}
		
		// remove ", " after latest name
		query = query[0:-2];
		
		query += ") VALUES (";
		
		foreach (Field data in fields) {
			query += "'" + validate(data.val) + "', ";
		}
		
		// remove ", " after latest name
		query = query[0:-2];
		
		query += ");";
		
		this.exec(query);
	}
	
	public void update(string table, Field[] fields, string id) {
		
		string query = "UPDATE " + table + " SET ";
		
		foreach (Field data in fields) {
			query += data.name + " = '" + validate(data.val) + "', ";
		}
		
		// remove ", " after latest name
		query = query[0:-2];
		
		query += " WHERE id = '" + id + "';";
	
		this.exec(query);
	}
	
	public void remove(string table, Field field) {
	
		string query = "DELETE FROM " + table + " WHERE " + field.name + " = '" + validate(field.val) + "';";
		
		this.exec(query);
	}
	
	public Field[,] search(string table, Field field) {
	
		string query = "SELECT * FROM " + table + " WHERE " + field.name + " = '" + validate(field.val) + "';";
		
		Field[,] fields = this.prepare(query);
		
		return fields;
	}
	
	public Field[,] prepare(string query) {
		int rc, row = 0, col, cols;
		Sqlite.Statement stmt;
		
		stderr.printf("Prepare: %s\n", query);
		rc = this.db.prepare(query, -1, out stmt, null);
		
		if (rc != Sqlite.OK) {
			stderr.printf("SQL error: %d, %s\n", rc, this.db.errmsg());
		}
		
		cols = stmt.column_count();
		stderr.printf("DB - Cols: %d\n", cols);
		
		
		// init array
		Field[,] fields = {};
		
		do {
			rc = stmt.step();
			switch (rc) {
				case Sqlite.DONE:
					break;
				case Sqlite.ROW:
					for (col = 0; col < cols; col++) {
						fields[row,cols] = Field() {
							name = stmt.column_name(col),
							val = stmt.column_text(col)
						};
					}
					
					// row read
					row++;
					break;
				default:
					stderr.printf("Error: %d, %s\n", rc, db.errmsg());
					break;
			}
		} while (rc == Sqlite.ROW);
		
		if (row != 0) {
			return fields;
		}
		else {
			return null;
		}
	}
	
	public void exec(string query) {
		int rc;
		
		stderr.printf("Exec: %s\n", query);
		rc = this.db.exec(query, null, null);
		
		if (rc != Sqlite.OK) {
			stderr.printf("SQL error: %d, %s\n", rc, this.db.errmsg());
		}
	}
	
	private string validate(string val) {
	
		// eliminate SQL injection
		val.replace("'", "\\'");
		
		return val;
	}
}