Implement FilePath Creation from Elements

- Implemented NewFilePath constructor for creating the FilePath from a given variadic set of path elements. #3
- Added docs for Root() and FilePath

filepath.go

@@ -1,16 +1,67 @@
 package moibit
 
+import (
+	"fmt"
+	"strings"
+)
+
+// FilePath represents the path to a file/directory in MOIBit.
 type FilePath struct {
 	elements  []string
 	extension string
 }
 
+// Root returns a FilePath object that points to file system root i.e "/"
 func Root() FilePath {
 	return FilePath{}
 }
 
+// NewFilePath generates a new FilePath from a given variadic set of path elements.
+// Each path element represents one level on the file system as a directory
+// and can contain any character except for periods (.) and slashes (/).
+//
+// The last element may contain a single period to represent a file with a name and an extension like
+// "file.json" or "hello.txt". If the last element has no period, the path is constructed for a directory
+//
+// An error is returned if any path element is invalid by not satisfying the above conditions.
+// If no elements are given, the returned FilePath references the root directory.
 func NewFilePath(elements ...string) (FilePath, error) {
-	return FilePath{}, nil
+	// Create a FilePath with initialized elements slice
+	fp := FilePath{make([]string, 0, len(elements)), ""}
+
+	// Iterate through the elements
+	for idx, element := range elements {
+		// If the element contains slash (/), throw an error
+		if strings.Contains(element, "/") {
+			return Root(), fmt.Errorf("failed to construct filepath: element '%v' contains slash", idx)
+		}
+
+		// If the element contains period (.)
+		if strings.Contains(element, ".") {
+			// Check if element is the last one
+			if idx == len(element)-1 {
+				// Split the element along the period and check if it contains only 2 split elements
+				split := strings.Split(element, ".")
+				if len(split) != 2 {
+					return Root(), fmt.Errorf("failed to construct filepath: last element contains multiple periods")
+				}
+
+				// Append the first split element into the fp elements (file name)
+				fp.elements = append(fp.elements, split[0])
+				// Set the file second split element as file extension
+				fp.extension = split[1]
+				continue
+			}
+
+			// Throw error for non-final element with period (.)
+			return Root(), fmt.Errorf("failed to construct filepath: non-final element '%v' contains period", idx)
+		}
+
+		// Append the element into the fp elements
+		fp.elements = append(fp.elements, element)
+	}
+
+	return fp, nil
 }
 
 func NewFilePathFromString(path string) (FilePath, error) {