package storage

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func TestDownloadObjectToTempSuccess(t *testing.T) {
	store := &FakeBackend{}
	store.SeedObject(FakeObject{Key: "sessions/a/current/run_id.txt", Data: []byte("run-123\n")})

	path, err := DownloadObjectToTemp(context.Background(), store, "sessions/a/current/run_id.txt", "narratio-test-*.txt")
	if err != nil {
		t.Fatalf("DownloadObjectToTemp() error = %v", err)
	}
	t.Cleanup(func() { _ = os.Remove(path) })

	data, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("ReadFile() error = %v", err)
	}
	if string(data) != "run-123\n" {
		t.Fatalf("downloaded data = %q, want %q", string(data), "run-123\n")
	}
}

func TestDownloadObjectToTempFailedDownloadRemovesTempFile(t *testing.T) {
	sentinel := errors.New("download failed")
	store := &FakeBackend{DownloadErr: sentinel}
	pattern := "narratio-test-fail-*.txt"
	before, err := filepath.Glob(filepath.Join(os.TempDir(), "narratio-test-fail-*.txt"))
	if err != nil {
		t.Fatalf("Glob(before) error = %v", err)
	}

	path, err := DownloadObjectToTemp(context.Background(), store, "sessions/a/current/run_id.txt", pattern)
	if !errors.Is(err, sentinel) {
		t.Fatalf("DownloadObjectToTemp() error = %v, want %v", err, sentinel)
	}
	if strings.TrimSpace(path) != "" {
		t.Fatalf("DownloadObjectToTemp() path = %q, want empty on failure", path)
	}
	after, err := filepath.Glob(filepath.Join(os.TempDir(), "narratio-test-fail-*.txt"))
	if err != nil {
		t.Fatalf("Glob(after) error = %v", err)
	}
	if len(after) != len(before) {
		t.Fatalf("temp file count changed after failed download: before=%d after=%d", len(before), len(after))
	}
}

func TestDownloadObjectToTempCallerContextWrappingPreservesCause(t *testing.T) {
	sentinel := errors.New("object missing")
	store := &FakeBackend{DownloadErr: sentinel}

	_, err := DownloadObjectToTemp(context.Background(), store, "sessions/a/current/run_id.txt", "narratio-test-*.txt")
	if err == nil {
		t.Fatal("DownloadObjectToTemp() error = nil, want error")
	}
	err = fmt.Errorf("download run pointer failed: %w", err)
	if !errors.Is(err, sentinel) {
		t.Fatalf("wrapped error does not preserve sentinel cause: %v", err)
	}
}