package generate

import (
	"crypto/rand"
	"encoding/hex"
	"log"
	"strings"
)

func id(prefix string, length int) string {
	var id [16]byte
	var buffer [32]byte
	builder := strings.Builder{}
	builder.Grow(length + 31)
	builder.WriteString(prefix)

	for builder.Len() < length {
		_, err := rand.Read(id[:])
		if err != nil {
			log.Panicln("generate.id: failed to use OS random:", err)
		}

		hex.Encode(buffer[:], id[:])
		builder.Write(buffer[:])
	}

	return builder.String()[:length]
}

func GroupID() string {
	return id("G", 16)
}

func ItemID() string {
	return id("I", 16)
}

func ProjectID() string {
	return id("P", 16)
}

func TaskID() string {
	return id("T", 16)
}

func LogID() string {
	return id("L", 16)
}

func GoalID() string {
	return id("A", 16)
}