/*
 * govis: unicode aware vis(3) encoding implementation
 * Copyright (C) 2017 SUSE LLC.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package govis

import (
	"crypto/rand"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

const DefaultVisFlags = VisWhite | VisOctal | VisGlob

func TestRandomVisUnvis(t *testing.T) {
	// Randomly generate N strings.
	const N = 100

	for i := 0; i < N; i++ {
		testBytes := make([]byte, 256)

		n, err := rand.Read(testBytes)
		require.NoErrorf(t, err, "read %d random bytes", len(testBytes))
		require.Equal(t, len(testBytes), n, "read unexpected number of bytes")

		test := string(testBytes)

		for flag := VisFlag(0); flag <= visMask; flag++ {
			// VisNoSlash is frankly just a dumb flag, and it is impossible
			// for us to actually preserve things in a round-trip.
			if flag&VisNoSlash == VisNoSlash {
				continue
			}

			enc, err := Vis(test, flag)
			require.NoErrorf(t, err, "vis(%q, %s)", test, flag)

			dec, err := Unvis(enc, flag)
			require.NoErrorf(t, err, "unvis(%q, %s)", enc, flag)

			if !assert.Equalf(t, test, dec, "unvis(vis(%q, %b) = %q, %b) round-trip", test, flag, enc, flag) {
				continue
			}
		}
	}
}

func TestRandomVisVisUnvisUnvis(t *testing.T) {
	// Randomly generate N strings.
	const N = 100

	for i := 0; i < N; i++ {
		testBytes := make([]byte, 256)

		n, err := rand.Read(testBytes)
		require.NoErrorf(t, err, "read %d random bytes", len(testBytes))
		require.Equal(t, len(testBytes), n, "read unexpected number of bytes")

		test := string(testBytes)

		for flag := VisFlag(0); flag <= visMask; flag++ {
			// VisNoSlash is frankly just a dumb flag, and it is impossible
			// for us to actually preserve things in a round-trip.
			if flag&VisNoSlash == VisNoSlash {
				continue
			}

			enc, err := Vis(test, flag)
			require.NoErrorf(t, err, "vis(%q, %s)", test, flag)

			enc2, err := Vis(enc, flag)
			require.NoErrorf(t, err, "vis(%q, %s)", enc, flag)

			dec2, err := Unvis(enc2, flag)
			require.NoErrorf(t, err, "unvis(%q, %s)", enc2, flag)

			dec, err := Unvis(dec2, flag)
			require.NoErrorf(t, err, "unvis(%q, %s)", dec2, flag)

			if !assert.Equalf(t, test, dec, "unvis(unvis(vis(vis(%q) = %q) = %q) = %q, %b) round-trip", test, enc, enc2, dec2, flag) {
				continue
			}
		}
	}
}

func TestVisUnvis(t *testing.T) {
	// Round-trip testing.
	for _, test := range []struct {
		name  string
		input string
	}{
		{"Empty", ""},
		{"Plain", "hello world"},
		{"Backslash", "THIS\\IS_A_TEST1234"},
		{"Punctuation", "this.is.a.normal_string"},
		{"Unicode1", "AC_Ra\u00edz_Certic\u00e1mara_S.A..pem"},
		{"Unicode2", "NetLock_Arany_=Class_Gold=_F\u0151tan\u00fas\u00edtv\u00e1ny.pem"},
		{"Unicode3", "T\u00dcB\u0130TAK_UEKAE_K\u00f6k_Sertifika_Hizmet_Sa\u011flay\u0131c\u0131s\u0131_-_S\u00fcr\u00fcm_3.pem"},
		{"ExtraPunctuation", "hello world [ this string needs=enco ding! ]"},
		{"Whitespace", "even \n more encoding necessary\a\a "},
		{"WeirdChars", "\024 <-- some more weird characters --> \u4f60\u597d\uff0c\u4e16\u754c"},
		{"DoubleEncoding", "\\xff\\n double encoding is also great fun \\x"},
		{"Unicode1-Encoded", "AC_Ra\\M-C\\M--z_Certic\\M-C\\M-!mara_S.A..pem"},
		{"Rand1", "z^i3i$\u00d3\u008anqgh5/t\u00e5<86>\u00b2kzla\\e^lv\u00df\u0093nv\u00df\u00aea|3}\u00d8\u0088\u00d6\u0084"},
		{"Rand2", `z^i3i$\M-C\M^S\M-B\M^Jnqgh5/t\M-C\M-%<86>\M-B\M-2kzla\\e^lv\M-C\M^_\M-B\M^Snv\M-C\M^_\M-B\M-.a|3}\M-C\M^X\M-B\M^H\M-C\M^V\M-B\M^D`},
		{"Rand3", "@?e1xs+.R_Kjo]7s8pgRP:*nXCE4{!c"},
		{"Rand4", "62_\u00c6\u00c62\u00ae\u00b7m\u00db\u00c3r^\u00bfp\u00c6u'q\u00fbc2\u00f0u\u00b8\u00dd\u00e8v\u00ff\u00b0\u00dc\u00c2\u00f53\u00db-k\u00f2sd4\\p\u00da\u00a6\u00d3\u00eea<\u00e6s{\u00a0p\u00f0\u00ffj\u00e0\u00e8\u00b8\u00b8\u00bc\u00fcb"},
		{"Rand4-Encoded", `62_\M-C\M^F\M-C\M^F2\M-B\M-.\M-B\M-7m\M-C\M^[\M-C\M^Cr^\M-B\M-?p\M-C\M^Fu'q\M-C\M-;c2\M-C\M-0u\M-B\M-8\M-C\M^]\M-C\M-(v\M-C\M-?\M-B\M-0\M-C\M^\\M-C\M^B\M-C\M-53\M-C\M^[-k\M-C\M-2sd4\\p\M-C\M^Z\M-B\M-&\M-C\M^S\M-C\M-.a<\M-C\M-&s{\M-B\240p\M-C\M-0\M-C\M-?j\M-C\240\M-C\M-(\M-B\M-8\M-B\M-8\M-B\M-<\M-C\M-<b`},
		{"Rand5", "\u9003\"9v1)T798|o;fly jnKX\u0489Be="},
		{"Rand5-Encoded", `\M-i\M^@\M^C"9v1)T798|o;fly jnKX\M-R\M^IBe=`},
		{"Rand6", "'3Ze\u050e|\u02del\u069du-Rpct4+Z5b={@_{b"},
		{"Rand6-Encoded", `'3Ze\M-T\M^N|\M-K\M^^l\M-Z\M^]u-Rpct4+Z5b={@_{b`},
		{"Rand7", "1\u00c6\u00abTcz+Vda?)k1%\\\"P;`po`h"},
		{"Rand7-Encoded", `1%C3%86%C2%ABTcz+Vda%3F)k1%25%5C%22P%3B%60po%60h`},
	} {
		t.Run(test.name, func(t *testing.T) {
			for flag := VisFlag(0); flag <= visMask; flag++ {
				// VisNoSlash is frankly just a dumb flag, and it is impossible for us
				// to actually preserve things in a round-trip.
				if flag&VisNoSlash == VisNoSlash {
					continue
				}

				enc, err := Vis(test.input, flag)
				require.NoErrorf(t, err, "vis(%q, %s)", test.input, flag)

				dec, err := Unvis(enc, flag)
				require.NoErrorf(t, err, "unvis(%q, %s)", enc, flag)

				if !assert.Equalf(t, test.input, dec, "unvis(vis(%q, %b) = %q, %b) round-trip", test, flag, enc, flag) {
					continue
				}
			}
		})
	}
}

func TestByteStrings(t *testing.T) {
	// It's important to make sure that we don't mess around with the layout of
	// bytes when doing a round-trip. Otherwise we risk outputting visually
	// identical but bit-stream non-identical strings (causing much confusion
	// when trying to access such files).

	for _, test := range []struct {
		name  string
		input []byte
	}{
		{"Unicode", []byte("This is a man in business suit levitating: \U0001f574")},
		{"ASCII", []byte{0x7f, 0x17, 0x01, 0x33}},
		// TODO: Test arbitrary byte streams like the one below. Currently this
		//       fails because Vis() is messing around with it (converting it
		//       to a rune and spacing it out).
		//{'\xef', '\xae', 'h', '\077', 'k'},
	} {
		t.Run(test.name, func(t *testing.T) {
			testString := string(test.input)

			enc, err := Vis(testString, DefaultVisFlags)
			require.NoErrorf(t, err, "vis(%q)", testString)

			dec, err := Unvis(enc, DefaultVisFlags)
			require.NoErrorf(t, err, "unvis(%q)", enc)

			assert.Equalf(t, testString, dec, "unvis(vis(%q) = %q) round-trip", testString, enc)
			assert.Equalf(t, test.input, []byte(dec), "unvis(vis(%q) = %q) round-trip", testString, enc)
		})
	}
}

func TestVisFlagsString(t *testing.T) {
	for _, test := range []struct {
		name     string
		flags    VisFlag
		expected string
	}{
		{"Empty", VisFlag(0), "0"},
		// Single valid flags.
		{"Single-VisOctal", VisOctal, "VisOctal"},
		{"Single-VisCStyle", VisCStyle, "VisCStyle"},
		{"Single-VisSpace", VisSpace, "VisSpace"},
		{"Single-VisTab", VisTab, "VisTab"},
		{"Single-VisNewline", VisNewline, "VisNewline"},
		{"Single-VisSafe", VisSafe, "VisSafe"},
		{"Single-VisNoSlash", VisNoSlash, "VisNoSlash"},
		{"Single-VisHTTPStyle", VisHTTPStyle, "VisHTTPStyle"},
		{"Single-VisGlob", VisGlob, "VisGlob"},
		// Invalid flag value.
		{"Unknown", VisFlag(0xff000), "0xff000"},
		// Multiple flag values.
		{"VisWhite", VisWhite, "VisSpace|VisTab|VisNewline"},
		{"DefaultVisFlags", DefaultVisFlags, "VisOctal|VisSpace|VisTab|VisNewline|VisGlob"},
		{"Multiple-Valid", VisOctal | VisCStyle | VisNoSlash | VisHTTPStyle, "VisOctal|VisCStyle|VisNoSlash|VisHTTPStyle"},
		{"Multiple-Mixed", VisOctal | VisSafe | 0xbeef0000, "VisOctal|VisSafe|0xbeef0000"},
	} {
		t.Run(test.name, func(t *testing.T) {
			got := test.flags.String()
			assert.Equal(t, test.expected, got, "VisFlag(%+x).String")
		})
	}
}