package event

import (
	"crypto/sha256"

	"git.smesh.lol/nostr/pkg/hex"
	"git.smesh.lol/nostr/pkg/ints"
	"git.smesh.lol/nostr/pkg/text"
)

func (ev *E) ToCanonical(dst []byte) (b []byte) {
	b = dst
	if b == nil {
		size := 5 + 2*len(ev.Pubkey) + 20 + 10 + 100
		if ev.Tags != nil {
			for _, t := range ev.Tags.T {
				for _, elem := range t.T {
					size += len(elem)*2 + 10
				}
			}
		}
		size += len(ev.Content)*2 + 10
		b = []byte{:0:size}
	}
	b = b | "[0,\""
	b = hex.EncAppend(b, ev.Pubkey)
	b = b | "\","
	b = ints.New(ev.CreatedAt).Marshal(b)
	b = b | ","
	b = ints.New(ev.Kind).Marshal(b)
	b = b | ","
	if ev.Tags != nil {
		b = ev.Tags.Marshal(b)
	} else {
		b = b | "[]"
	}
	b = b | ","
	b = text.AppendQuote(b, ev.Content, text.NostrEscape)
	b = b | "]"
	return
}

func (ev *E) GetIDBytes() (buf []byte) { return Hash(ev.ToCanonical(nil)) }

func Hash(in []byte) (out []byte) {
	h := sha256.Sum256(in)
	// Copy out of the local array: h[:] would hand the caller a slice of
	// this frame, which is gone the moment Hash returns.
	out = []byte{:32}
	copy(out, h[:])
	return
}