Able to read workflows

19/code.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type Node struct {
+	isExpression bool
+	greater      bool
+	id           string
+	value        int
+	wrong        *Node
+	right        *Node
+}
+
+type Workflow struct {
+	id         string
+	expression *Node
+}
+
+func parseExpression(text string) []Node {
+	var nodes []Node
+	if !strings.Contains(text, ",") {
+		var node Node
+		var parts []string
+		if strings.Contains(text, ">") {
+			node.greater = true
+			parts = strings.Split(text, ">")
+		} else if strings.Contains(text, "<") {
+			parts = strings.Split(text, "<")
+		} else {
+			node.id = text
+			nodes = append(nodes, node)
+			return nodes
+		}
+
+		if len(parts) != 2 {
+			log.Fatalf("Can't parse expression: %s", text)
+		}
+
+		node.id = parts[0]
+		n, err := strconv.Atoi(parts[1])
+		if err != nil {
+			log.Fatalf("Can't parse a number %s: %s", parts[1], err)
+		}
+		node.value = n
+
+		nodes = append(nodes, node)
+	} else {
+		parts := strings.Split(text, ",")
+		if len(parts) != 2 {
+			log.Fatalf("Wrong number of parts from: %s", text)
+		}
+
+		for i := range parts {
+			if strings.ContainsAny(parts[i], "<>") {
+				nodes = append(nodes, parseExpression(parts[i])...)
+			} else {
+				nodes = append(nodes, Node{id: parts[i]})
+			}
+		}
+	}
+
+	return nodes
+}
+
+func parseWorkflow(line string) Workflow {
+	var workflow Workflow
+	idAndExpression := strings.Split(line, "{")
+	if len(idAndExpression) != 2 {
+		log.Fatalf("Can't extract id and expression from: %s", line)
+	}
+
+	workflow.id = idAndExpression[0]
+	expressions := strings.Split(strings.TrimRight(idAndExpression[1], "}"), ":")
+	if len(expressions) < 2 {
+		log.Fatalf("Can't extract expressions from: %s", idAndExpression[1])
+	}
+
+	first := parseExpression(expressions[0])
+	if len(first) != 1 {
+		log.Fatalf("First expression should be single one: %s", expressions[0])
+	}
+
+	workflow.expression = &first[0]
+	current := workflow.expression
+	for i := 1; i < len(expressions); i++ {
+		ex := parseExpression(expressions[i])
+		if len(ex) != 2 {
+			log.Fatalf("Need two: %s", expressions[i])
+		}
+
+		current.right = &ex[0]
+		if current.right.isExpression {
+			current = current.right
+		}
+
+		current.wrong = &ex[1]
+		if current.wrong.isExpression {
+			current = current.wrong
+		}
+	}
+
+	return workflow
+}
+
+func readInput(file *os.File) map[string]Workflow {
+	scanner := bufio.NewScanner(file)
+	workflows := make(map[string]Workflow)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "" {
+			break
+		}
+
+		workflow := parseWorkflow(line)
+		workflows[workflow.id] = workflow
+	}
+
+	return workflows
+}
+
+func main() {
+	if len(os.Args) < 2 {
+		log.Fatal("You need to specify a file!")
+	}
+
+	filePath := os.Args[1]
+	file, err := os.Open(filePath)
+	if err != nil {
+		log.Fatalf("Failed to open %s!\n", filePath)
+
+	}
+
+	workflows := readInput(file)
+	fmt.Println(workflows)
+}