package dmidecode

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"os/exec"
	"strings"

	values "github.com/rancher/wrangler/pkg/data"
	"github.com/rancher/wrangler/pkg/kv"
)

func Decode() (map[string]interface{}, error) {
	buf := &bytes.Buffer{}
	cmd := exec.Command("dmidecode")
	cmd.Stdout = buf

	if err := cmd.Run(); err != nil {
		return nil, fmt.Errorf("looking up SMBIOS tables (using dmidecode): %w", err)
	}

	return dmiOutputToMap(buf), nil
}

func dmiOutputToMap(buf io.Reader) map[string]interface{} {
	var (
		result    = map[string]interface{}{}
		scanner   = bufio.NewScanner(buf)
		start     = false
		lastKey   []string
		stopLines = map[string]bool{
			"OEM-specific Type": true,
			"End Of Table":      true,
		}
	)

	for scanner.Scan() {
		line := scanner.Text()
		if strings.HasPrefix(line, "Handle ") {
			start = true
			continue
		} else if strings.TrimSpace(line) == "" || !start || stopLines[line] {
			start = false
			continue
		}

		var key []string
		for strings.HasPrefix(line, "\t") {
			line = strings.TrimPrefix(line, "\t")
			if len(lastKey) > len(key) {
				key = append(key, lastKey[len(key)])
			}
		}
		name, value := kv.Split(line, ": ")
		key = append(key, name)

		if strings.TrimSpace(value) != "" || strings.Contains(line, ":") {
			values.PutValue(result, value, key...)
		} else if len(key) > 1 {
			parentKey := key[:len(key)-1]
			parentValue := values.GetValueN(result, parentKey...)
			if parentSlice, ok := parentValue.([]interface{}); ok {
				parentValue = append(parentSlice, name)
			} else {
				parentValue = []interface{}{name}
			}
			values.PutValue(result, parentValue, parentKey...)
		} else {
			values.PutValue(result, map[string]interface{}{}, key...)
		}

		lastKey = key
	}

	return result
}