Implement validation command

I just need to fill base.schema with the simplest possible test case now

cmd/obp/cmd/root.go

@@ -16,6 +16,7 @@ var cfgFile string
 
 // rootCmd represents the base command when called without any subcommands
 var rootCmd = &cobra.Command{
+	TraverseChildren: true,
 	Use:              "obp",
 	Short:            "obp is a toolkit for managing your vault in headless contexts",
 	Long:             `a suite of tools for managing your obsidian vault`,

cmd/obp/cmd/validate.go

@@ -4,26 +4,81 @@ Copyright © 2023 NAME HERE <EMAIL ADDRESS>
 package cmd
 
 import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+
+	"github.com/santhosh-tekuri/jsonschema/v5"
 	"github.com/spf13/cobra"
+	"gopkg.in/yaml.v3"
 )
 
 // rootCmd represents the base command when called without any subcommands
 var validateCmd = &cobra.Command{
 	Use:   "validate",
 	Short: "loads a note and ensures its frontmatter follows the provided protobuf schema",
-	Long: `parses frontmatter in a markdown note and attempts to write the struct out using the provided protobuf schema.
+	Long: `Validate YAML frontmatter with jsonschema
-
-If the write succeeds, the data satisfies the schema.
 `,
 	// Uncomment the following line if your bare application
 	// has an action associated with it:
-	// Run: func(cmd *cobra.Command, args []string) { },
+	PreRunE: func(cmd *cobra.Command, args []string) error {
+		schemaFilename := cmd.Flag("schema").Value.String()
+		if len(schemaFilename) == 0 {
+			return fmt.Errorf("Please profide a schema filename")
+		}
+		target := cmd.Flag("target").Value.String()
+		if len(target) == 0 {
+			return fmt.Errorf("Please profide a target filename")
+		}
+		return nil
+	},
+	Run: func(cmd *cobra.Command, args []string) {
+		var m interface{}
+		var schemaBytes bytes.Buffer
+
+		schemaFilename := cmd.Flag("schema").Value.String()
+		schemaFile, err := os.Open(schemaFilename)
+		if err != nil {
+			log.Fatalf("could not open schema file: %s\n", err)
+		}
+		io.Copy(&schemaBytes, schemaFile)
+
+		// err := yaml.Unmarshal([]byte(yamlText), &m)
+		targetFilename := cmd.Flag("target").Value.String()
+		target, err := os.Open(targetFilename)
+		if err != nil {
+			log.Fatalf("could not open target file: %s\n", err)
+		}
+		dec := yaml.NewDecoder(target)
+		err = dec.Decode(&m)
+		if err != nil {
+			log.Fatalf("error decoding YAML: %s\n", err)
+		}
+
+		compiler := jsonschema.NewCompiler()
+		if err := compiler.AddResource(schemaFilename, strings.NewReader(schemaBytes.String())); err != nil {
+			log.Fatalf("error adding resource to jsonschema compiler: %s\n", err)
+		}
+
+		schema, err := compiler.Compile("schema.json")
+		if err != nil {
+			log.Fatalf("error compiling schema: %s\n", err)
+		}
+		if err := schema.Validate(m); err != nil {
+			log.Fatalf("error validating: %s\n", err)
+		}
+		fmt.Println("validation successfull")
+	},
 }
 
 func init() {
 	// Cobra also supports local flags, which will only run
 	// when this action is called directly.
 	// rootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
-	validateCmd.Flags().StringP("schema", "s", "schema.proto", "path to protobuf file")
+	validateCmd.Flags().StringP("schema", "s", "base.schema", "path to protobuf file")
+	validateCmd.Flags().StringP("target", "t", "", "list of filenames to validate")
 	rootCmd.AddCommand(validateCmd)
 }