package pkg_test

import (
	"bytes"
	"crypto/sha512"
	"encoding/base64"
	"io/fs"
	"os"
	"path/filepath"
	"reflect"
	"syscall"
	"testing"

	"hakurei.app/container"
	"hakurei.app/container/check"
	"hakurei.app/container/stub"
	"hakurei.app/internal/pkg"
)

// cacheTestCase is a test case passed to checkWithCache where a new instance
// of [pkg.Cache] is prepared for the test case, and is validated and removed
// on test completion.
type cacheTestCase struct {
	name  string
	early func(t *testing.T, base *check.Absolute)
	f     func(t *testing.T, base *check.Absolute, c *pkg.Cache)
	want  pkg.Checksum
}

// checkWithCache runs a slice of cacheTestCase.
func checkWithCache(t *testing.T, testCases []cacheTestCase) {
	t.Helper()

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()

			base := check.MustAbs(t.TempDir())
			if err := os.Chmod(base.String(), 0700); err != nil {
				t.Fatal(err)
			}
			t.Cleanup(func() {
				if err := filepath.WalkDir(base.String(), func(path string, d fs.DirEntry, err error) error {
					if err != nil {
						t.Error(err)
						return nil
					}
					if !d.IsDir() {
						return nil
					}
					return os.Chmod(path, 0700)
				}); err != nil {
					t.Fatal(err)
				}
			})

			if c, err := pkg.New(base); err != nil {
				t.Fatalf("New: error = %v", err)
			} else {
				if tc.early != nil {
					tc.early(t, base)
				}
				tc.f(t, base, c)
			}

			if checksum, err := pkg.HashDir(base); err != nil {
				t.Fatalf("HashDir: error = %v", err)
			} else if checksum != tc.want {
				t.Fatalf("HashDir: %v", &pkg.ChecksumMismatchError{
					Got:  checksum,
					Want: tc.want,
				})
			}
		})
	}
}

func TestCache(t *testing.T) {
	t.Parallel()

	const testdata = "" +
		"\x00\x00\x00\x00" +
		"\xad\x0b\x00" +
		"\x04" +
		"\xfe\xfe\x00\x00" +
		"\xfe\xca\x00\x00"

	testdataChecksum := func() pkg.Checksum {
		h := sha512.New384()
		h.Write([]byte(testdata))
		return (pkg.Checksum)(h.Sum(nil))
	}()

	testdataChecksumString := base64.URLEncoding.EncodeToString(testdataChecksum[:])

	testCases := []cacheTestCase{
		{"file", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
			wantErrNonexistent := &os.PathError{
				Op: "open",
				Path: base.Append(
					"identifier",
					testdataChecksumString,
				).String(),
				Err: syscall.ENOENT,
			}
			if _, _, err := c.LoadFile(testdataChecksum); !reflect.DeepEqual(err, wantErrNonexistent) {
				t.Fatalf("LoadFile: error = %#v, want %#v", err, wantErrNonexistent)
			}

			identifier := (pkg.ID)(bytes.Repeat([]byte{
				0x75, 0xe6, 0x9d, 0x6d, 0xe7, 0x9f,
			}, 8))
			wantPathname := base.Append(
				"identifier",
				"deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef",
			)
			identifier0 := (pkg.ID)(bytes.Repeat([]byte{
				0x71, 0xa7, 0xde, 0x6d, 0xa6, 0xde,
			}, 8))
			wantPathname0 := base.Append(
				"identifier",
				"cafebabecafebabecafebabecafebabecafebabecafebabecafebabecafebabe",
			)

			// initial store
			if pathname, err := c.StoreFile(
				identifier,
				[]byte(testdata),
				&testdataChecksum,
				true,
			); err != nil {
				t.Fatalf("StoreFile: error = %v", err)
			} else if !pathname.Is(wantPathname) {
				t.Fatalf("StoreFile: pathname = %q, want %q", pathname, wantPathname)
			}

			// load or store, identical content
			if pathname, data, store, err := c.LoadOrStoreFile(identifier0, func() ([]byte, error) {
				return []byte(testdata), nil
			}, &testdataChecksum, true); err != nil {
				t.Fatalf("LoadOrStoreFile: error = %v", err)
			} else if !pathname.Is(wantPathname0) {
				t.Fatalf("LoadOrStoreFile: pathname = %q, want %q", pathname, wantPathname0)
			} else if string(data) != testdata {
				t.Fatalf("LoadOrStoreFile: data = %x, want %x", data, testdata)
			} else if !store {
				t.Fatal("LoadOrStoreFile did not store nonpresent entry")
			}

			// load or store, existing entry
			if pathname, data, store, err := c.LoadOrStoreFile(identifier, func() ([]byte, error) {
				return []byte(testdata), nil
			}, &testdataChecksum, true); err != nil {
				t.Fatalf("LoadOrStoreFile: error = %v", err)
			} else if !pathname.Is(wantPathname) {
				t.Fatalf("LoadOrStoreFile: pathname = %q, want %q", pathname, wantPathname)
			} else if string(data) != testdata {
				t.Fatalf("LoadOrStoreFile: data = %x, want %x", data, testdata)
			} else if store {
				t.Fatal("LoadOrStoreFile stored over present entry")
			}

			// load, existing entry
			if pathname, data, err := c.LoadFile(identifier0); err != nil {
				t.Fatalf("LoadFile: error = %v", err)
			} else if !pathname.Is(wantPathname0) {
				t.Fatalf("LoadFile: pathname = %q, want %q", pathname, wantPathname0)
			} else if string(data) != testdata {
				t.Fatalf("LoadFile: data = %x, want %x", data, testdata)
			}

			// checksum mismatch
			wantErrChecksum := &pkg.ChecksumMismatchError{
				Got: testdataChecksum,
			}
			if _, err := c.StoreFile(
				testdataChecksum,
				[]byte(testdata),
				new(pkg.Checksum),
				true,
			); !reflect.DeepEqual(err, wantErrChecksum) {
				t.Fatalf("StoreFile: error = %#v, want %#v", err, wantErrChecksum)
			}

			// verify failed store
			if _, _, err := c.LoadFile(testdataChecksum); !reflect.DeepEqual(err, wantErrNonexistent) {
				t.Fatalf("LoadFile: error = %#v, want %#v", err, wantErrNonexistent)
			}

			// store, same identifier
			wantPathnameF := base.Append(
				"identifier",
				testdataChecksumString,
			)
			if pathname, err := c.StoreFile(
				testdataChecksum,
				[]byte(testdata),
				&testdataChecksum,
				true,
			); err != nil {
				t.Fatalf("StoreFile: error = %v", err)
			} else if !pathname.Is(wantPathnameF) {
				t.Fatalf("StoreFile: pathname = %q, want %q", pathname, wantPathnameF)
			}

			// load, same identifier
			if pathname, data, err := c.LoadFile(testdataChecksum); err != nil {
				t.Fatalf("LoadFile: error = %v", err)
			} else if !pathname.Is(wantPathnameF) {
				t.Fatalf("LoadFile: pathname = %q, want %q", pathname, wantPathnameF)
			} else if string(data) != testdata {
				t.Fatalf("LoadFile: data = %x, want %x", data, testdata)
			}

			// store without validation
			wantChecksum := pkg.Checksum{
				0xbe, 0xc0, 0x21, 0xb4, 0xf3, 0x68,
				0xe3, 0x06, 0x91, 0x34, 0xe0, 0x12,
				0xc2, 0xb4, 0x30, 0x70, 0x83, 0xd3,
				0xa9, 0xbd, 0xd2, 0x06, 0xe2, 0x4e,
				0x5f, 0x0d, 0x86, 0xe1, 0x3d, 0x66,
				0x36, 0x65, 0x59, 0x33, 0xec, 0x2b,
				0x41, 0x34, 0x65, 0x96, 0x68, 0x17,
				0xa9, 0xc2, 0x08, 0xa1, 0x17, 0x17,
			}
			var gotChecksum pkg.Checksum
			wantPathnameG := base.Append(
				"identifier",
				base64.URLEncoding.EncodeToString(wantChecksum[:]),
			)
			if pathname, err := c.StoreFile(
				wantChecksum,
				[]byte{0},
				&gotChecksum,
				false,
			); err != nil {
				t.Fatalf("StoreFile: error = %#v", err)
			} else if !pathname.Is(wantPathnameG) {
				t.Fatalf("StoreFile: pathname = %q, want %q", pathname, wantPathnameG)
			} else if gotChecksum != wantChecksum {
				t.Fatalf("StoreFile: buf = %x, want %x", gotChecksum, wantChecksum)
			}

			// makeData passthrough
			var zeroIdent pkg.ID
			wantErrPassthrough := stub.UniqueError(0xcafe)
			if _, _, _, err := c.LoadOrStoreFile(zeroIdent, func() ([]byte, error) {
				return nil, wantErrPassthrough
			}, new(pkg.Checksum), true); !reflect.DeepEqual(err, wantErrPassthrough) {
				t.Fatalf("LoadOrStoreFile: error = %#v, want %#v", err, wantErrPassthrough)
			}

			// verify failed store
			wantErrNonexistentZero := &os.PathError{
				Op: "open",
				Path: base.Append(
					"identifier",
					"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
				).String(),
				Err: syscall.ENOENT,
			}
			if _, _, err := c.LoadFile(zeroIdent); !reflect.DeepEqual(err, wantErrNonexistentZero) {
				t.Fatalf("LoadFile: error = %#v, want %#v", err, wantErrNonexistentZero)
			}
		}, pkg.MustDecode("ZNSQH-mjhtIbFvi51lQ0UjatjoS8_5ILrBPNWlO2LWTq9P6MJEnekYzP0esUJnVr")},
	}
	checkWithCache(t, testCases)
}

func TestErrors(t *testing.T) {
	t.Parallel()

	testCases := []struct {
		name string
		err  error
		want string
	}{
		{"ChecksumMismatchError", &pkg.ChecksumMismatchError{
			Want: (pkg.Checksum)(bytes.Repeat([]byte{
				0x75, 0xe6, 0x9d, 0x6d, 0xe7, 0x9f,
			}, 8)),
		}, "got AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" +
			" instead of deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef"},
	}
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()

			if got := tc.err.Error(); got != tc.want {
				t.Errorf("Error: %q, want %q", got, tc.want)
			}
		})
	}
}

func TestNew(t *testing.T) {
	t.Parallel()

	t.Run("nonexistent", func(t *testing.T) {
		t.Parallel()

		wantErr := &os.PathError{
			Op:   "mkdir",
			Path: container.Nonexistent,
			Err:  syscall.ENOENT,
		}
		if _, err := pkg.New(check.MustAbs(container.Nonexistent)); !reflect.DeepEqual(err, wantErr) {
			t.Errorf("New: error = %#v, want %#v", err, wantErr)
		}
	})

	t.Run("permission", func(t *testing.T) {
		t.Parallel()

		tempDir := check.MustAbs(t.TempDir())
		if err := os.Chmod(tempDir.String(), 0); err != nil {
			t.Fatal(err)
		} else {
			t.Cleanup(func() {
				if err = os.Chmod(tempDir.String(), 0700); err != nil {
					t.Fatal(err)
				}
			})
		}

		wantErr := &os.PathError{
			Op:   "mkdir",
			Path: tempDir.Append("cache").String(),
			Err:  syscall.EACCES,
		}
		if _, err := pkg.New(tempDir.Append("cache")); !reflect.DeepEqual(err, wantErr) {
			t.Errorf("New: error = %#v, want %#v", err, wantErr)
		}
	})
}