package storage

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"io"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func newTestStore(t *testing.T) *FilesystemStore {
	t.Helper()
	fs, err := NewFilesystemStore(t.TempDir())
	if err != nil {
		t.Fatalf("NewFilesystemStore: %v", err)
	}
	return fs
}

func TestNewFilesystemStore(t *testing.T) {
	dir := t.TempDir()
	sub := filepath.Join(dir, "a", "b")
	fs, err := NewFilesystemStore(sub)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !filepath.IsAbs(fs.root) {
		t.Errorf("root is not absolute: %s", fs.root)
	}
	info, err := os.Stat(sub)
	if err != nil {
		t.Fatalf("root dir missing: %v", err)
	}
	if !info.IsDir() {
		t.Error("root is not a directory")
	}
}

func TestPut(t *testing.T) {
	fs := newTestStore(t)
	ctx := context.Background()
	data := []byte("hello world")
	h := sha256.Sum256(data)
	wantChecksum := hex.EncodeToString(h[:])

	result, err := fs.Put(ctx, "items/P001/rev1.FCStd", bytes.NewReader(data), int64(len(data)), "application/octet-stream")
	if err != nil {
		t.Fatalf("Put: %v", err)
	}
	if result.Key != "items/P001/rev1.FCStd" {
		t.Errorf("Key = %q, want %q", result.Key, "items/P001/rev1.FCStd")
	}
	if result.Size != int64(len(data)) {
		t.Errorf("Size = %d, want %d", result.Size, len(data))
	}
	if result.Checksum != wantChecksum {
		t.Errorf("Checksum = %q, want %q", result.Checksum, wantChecksum)
	}

	// Verify file on disk.
	got, err := os.ReadFile(fs.path("items/P001/rev1.FCStd"))
	if err != nil {
		t.Fatalf("reading file: %v", err)
	}
	if !bytes.Equal(got, data) {
		t.Error("file content mismatch")
	}
}

func TestPutAtomicity(t *testing.T) {
	fs := newTestStore(t)
	ctx := context.Background()
	key := "test/atomic.bin"

	// Write an initial file.
	if _, err := fs.Put(ctx, key, strings.NewReader("original"), 8, ""); err != nil {
		t.Fatalf("initial Put: %v", err)
	}

	// Write with a reader that fails partway through.
	failing := io.MultiReader(strings.NewReader("partial"), &errReader{})
	_, err := fs.Put(ctx, key, failing, 100, "")
	if err == nil {
		t.Fatal("expected error from failing reader")
	}

	// Original file should still be intact.
	got, err := os.ReadFile(fs.path(key))
	if err != nil {
		t.Fatalf("reading file after failed put: %v", err)
	}
	if string(got) != "original" {
		t.Errorf("file content = %q, want %q", got, "original")
	}
}

type errReader struct{}

func (e *errReader) Read([]byte) (int, error) {
	return 0, io.ErrUnexpectedEOF
}

func TestGet(t *testing.T) {
	fs := newTestStore(t)
	ctx := context.Background()
	data := []byte("test content")

	if _, err := fs.Put(ctx, "f.txt", bytes.NewReader(data), int64(len(data)), ""); err != nil {
		t.Fatalf("Put: %v", err)
	}

	rc, err := fs.Get(ctx, "f.txt")
	if err != nil {
		t.Fatalf("Get: %v", err)
	}
	defer rc.Close()

	got, err := io.ReadAll(rc)
	if err != nil {
		t.Fatalf("ReadAll: %v", err)
	}
	if !bytes.Equal(got, data) {
		t.Error("content mismatch")
	}
}

func TestGetMissing(t *testing.T) {
	fs := newTestStore(t)
	_, err := fs.Get(context.Background(), "no/such/file")
	if err == nil {
		t.Fatal("expected error for missing file")
	}
}

func TestGetVersion(t *testing.T) {
	fs := newTestStore(t)
	ctx := context.Background()
	data := []byte("versioned")

	if _, err := fs.Put(ctx, "v.txt", bytes.NewReader(data), int64(len(data)), ""); err != nil {
		t.Fatalf("Put: %v", err)
	}

	// GetVersion ignores versionID, returns same file.
	rc, err := fs.GetVersion(ctx, "v.txt", "ignored-version-id")
	if err != nil {
		t.Fatalf("GetVersion: %v", err)
	}
	defer rc.Close()

	got, err := io.ReadAll(rc)
	if err != nil {
		t.Fatalf("ReadAll: %v", err)
	}
	if !bytes.Equal(got, data) {
		t.Error("content mismatch")
	}
}

func TestDelete(t *testing.T) {
	fs := newTestStore(t)
	ctx := context.Background()

	if _, err := fs.Put(ctx, "del.txt", strings.NewReader("x"), 1, ""); err != nil {
		t.Fatalf("Put: %v", err)
	}

	if err := fs.Delete(ctx, "del.txt"); err != nil {
		t.Fatalf("Delete: %v", err)
	}

	if _, err := os.Stat(fs.path("del.txt")); !os.IsNotExist(err) {
		t.Error("file still exists after delete")
	}
}

func TestDeleteMissing(t *testing.T) {
	fs := newTestStore(t)
	if err := fs.Delete(context.Background(), "no/such/file"); err != nil {
		t.Fatalf("Delete missing file should not error: %v", err)
	}
}

func TestExists(t *testing.T) {
	fs := newTestStore(t)
	ctx := context.Background()

	ok, err := fs.Exists(ctx, "nope")
	if err != nil {
		t.Fatalf("Exists: %v", err)
	}
	if ok {
		t.Error("Exists returned true for missing file")
	}

	if _, err := fs.Put(ctx, "yes.txt", strings.NewReader("y"), 1, ""); err != nil {
		t.Fatalf("Put: %v", err)
	}

	ok, err = fs.Exists(ctx, "yes.txt")
	if err != nil {
		t.Fatalf("Exists: %v", err)
	}
	if !ok {
		t.Error("Exists returned false for existing file")
	}
}

func TestCopy(t *testing.T) {
	fs := newTestStore(t)
	ctx := context.Background()
	data := []byte("copy me")

	if _, err := fs.Put(ctx, "src.bin", bytes.NewReader(data), int64(len(data)), ""); err != nil {
		t.Fatalf("Put: %v", err)
	}

	if err := fs.Copy(ctx, "src.bin", "deep/nested/dst.bin"); err != nil {
		t.Fatalf("Copy: %v", err)
	}

	got, err := os.ReadFile(fs.path("deep/nested/dst.bin"))
	if err != nil {
		t.Fatalf("reading copied file: %v", err)
	}
	if !bytes.Equal(got, data) {
		t.Error("copied content mismatch")
	}

	// Source should still exist.
	if _, err := os.Stat(fs.path("src.bin")); err != nil {
		t.Error("source file missing after copy")
	}
}

func TestPresignPut(t *testing.T) {
	fs := newTestStore(t)
	_, err := fs.PresignPut(context.Background(), "key", 5*60)
	if err != ErrPresignNotSupported {
		t.Errorf("PresignPut error = %v, want ErrPresignNotSupported", err)
	}
}

func TestPing(t *testing.T) {
	fs := newTestStore(t)
	if err := fs.Ping(context.Background()); err != nil {
		t.Fatalf("Ping: %v", err)
	}
}

func TestPingBadRoot(t *testing.T) {
	fs := &FilesystemStore{root: "/nonexistent/path/that/should/not/exist"}
	if err := fs.Ping(context.Background()); err == nil {
		t.Fatal("expected Ping to fail with invalid root")
	}
}

func TestPutOverwrite(t *testing.T) {
	fs := newTestStore(t)
	ctx := context.Background()

	if _, err := fs.Put(ctx, "ow.txt", strings.NewReader("first"), 5, ""); err != nil {
		t.Fatalf("Put: %v", err)
	}
	if _, err := fs.Put(ctx, "ow.txt", strings.NewReader("second"), 6, ""); err != nil {
		t.Fatalf("Put overwrite: %v", err)
	}

	got, _ := os.ReadFile(fs.path("ow.txt"))
	if string(got) != "second" {
		t.Errorf("content = %q, want %q", got, "second")
	}
}