package main

import (
	"bytes"
	"errors"
	"io"
	"io/fs"
	"path/filepath"
	"testing"
)

// blobPath points tests at the default disk store's file for a blob id —
// test-only sugar (asserting bytes really live on disk / were unlinked).
// Production code goes through db.blobs and must not assume bytes are files.
func (db *DB) blobPath(id string) string { return db.blobs.(*diskBlobStore).path(id) }

// The blobStore contract, exercised against implementation #1 (disk): a staged
// write committed under an id round-trips byte-for-byte, and remove makes it
// unopenable. Any future implementation (an object store, per issue #550) must
// pass this same sequence.
func TestDiskBlobStoreRoundTrip(t *testing.T) {
	store, err := newDiskBlobStore(filepath.Join(t.TempDir(), "blobs"))
	if err != nil {
		t.Fatalf("newDiskBlobStore: %v", err)
	}
	payload := []byte("pretend-this-is-encrypted-bytes\x00\x01\x02")

	// put: stream in two writes to prove staging accumulates, then publish.
	w, err := store.create()
	if err != nil {
		t.Fatalf("create: %v", err)
	}
	if _, err := w.Write(payload[:10]); err != nil {
		t.Fatalf("write: %v", err)
	}
	if _, err := w.Write(payload[10:]); err != nil {
		t.Fatalf("write: %v", err)
	}
	if err := w.commit("blobid_123-abc"); err != nil {
		t.Fatalf("commit: %v", err)
	}

	// open: bytes, size, and a usable modtime all come back.
	r, size, modTime, err := store.open("blobid_123-abc")
	if err != nil {
		t.Fatalf("open: %v", err)
	}
	got, err := io.ReadAll(r)
	r.Close()
	if err != nil || !bytes.Equal(got, payload) {
		t.Fatalf("round-trip mismatch: err=%v got=%q", err, got)
	}
	if size != int64(len(payload)) {
		t.Fatalf("size = %d, want %d", size, len(payload))
	}
	if modTime.IsZero() {
		t.Fatal("zero modtime")
	}

	// delete → open fails with the contractual not-exist error.
	if err := store.remove("blobid_123-abc"); err != nil {
		t.Fatalf("remove: %v", err)
	}
	if _, _, _, err := store.open("blobid_123-abc"); !errors.Is(err, fs.ErrNotExist) {
		t.Fatalf("open after remove: want fs.ErrNotExist, got %v", err)
	}
	// GC unlinks best-effort, so removing an id that's already gone is not an
	// error.
	if err := store.remove("blobid_123-abc"); err != nil {
		t.Fatalf("remove of missing id: %v", err)
	}
}

// An aborted staged write leaves nothing fetchable — the id is never published.
func TestDiskBlobStoreAbortDiscards(t *testing.T) {
	store, err := newDiskBlobStore(filepath.Join(t.TempDir(), "blobs"))
	if err != nil {
		t.Fatalf("newDiskBlobStore: %v", err)
	}
	w, err := store.create()
	if err != nil {
		t.Fatalf("create: %v", err)
	}
	if _, err := w.Write([]byte("half an upload")); err != nil {
		t.Fatalf("write: %v", err)
	}
	w.abort()
	if _, _, _, err := store.open("neverpublished"); !errors.Is(err, fs.ErrNotExist) {
		t.Fatalf("open of aborted write: want fs.ErrNotExist, got %v", err)
	}
}