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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lzw

import (
        "bytes"
        "io"
        "io/ioutil"
        "runtime"
        "strconv"
        "strings"
        "testing"
)

type lzwTest struct {
        desc       string
        raw        string
        compressed string
        err        error
}

var lzwTests = []lzwTest{
        {
                "empty;LSB;8",
                "",
                "\x01\x01",
                nil,
        },
        {
                "empty;MSB;8",
                "",
                "\x80\x80",
                nil,
        },
        {
                "tobe;LSB;7",
                "TOBEORNOTTOBEORTOBEORNOT",
                "\x54\x4f\x42\x45\x4f\x52\x4e\x4f\x54\x82\x84\x86\x8b\x85\x87\x89\x81",
                nil,
        },
        {
                "tobe;LSB;8",
                "TOBEORNOTTOBEORTOBEORNOT",
                "\x54\x9e\x08\x29\xf2\x44\x8a\x93\x27\x54\x04\x12\x34\xb8\xb0\xe0\xc1\x84\x01\x01",
                nil,
        },
        {
                "tobe;MSB;7",
                "TOBEORNOTTOBEORTOBEORNOT",
                "\x54\x4f\x42\x45\x4f\x52\x4e\x4f\x54\x82\x84\x86\x8b\x85\x87\x89\x81",
                nil,
        },
        {
                "tobe;MSB;8",
                "TOBEORNOTTOBEORTOBEORNOT",
                "\x2a\x13\xc8\x44\x52\x79\x48\x9c\x4f\x2a\x40\xa0\x90\x68\x5c\x16\x0f\x09\x80\x80",
                nil,
        },
        {
                "tobe-truncated;LSB;8",
                "TOBEORNOTTOBEORTOBEORNOT",
                "\x54\x9e\x08\x29\xf2\x44\x8a\x93\x27\x54\x04",
                io.ErrUnexpectedEOF,
        },
        // This example comes from http://en.wikipedia.org/wiki/Graphics_Interchange_Format.
        {
                "gif;LSB;8",
                "\x28\xff\xff\xff\x28\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff",
                "\x00\x51\xfc\x1b\x28\x70\xa0\xc1\x83\x01\x01",
                nil,
        },
        // This example comes from http://compgroups.net/comp.lang.ruby/Decompressing-LZW-compression-from-PDF-file
        {
                "pdf;MSB;8",
                "-----A---B",
                "\x80\x0b\x60\x50\x22\x0c\x0c\x85\x01",
                nil,
        },
}

func TestReader(t *testing.T) {
        var b bytes.Buffer
        for _, tt := range lzwTests {
                d := strings.Split(tt.desc, ";")
                var order Order
                switch d[1] {
                case "LSB":
                        order = LSB
                case "MSB":
                        order = MSB
                default:
                        t.Errorf("%s: bad order %q", tt.desc, d[1])
                }
                litWidth, _ := strconv.Atoi(d[2])
                rc := NewReader(strings.NewReader(tt.compressed), order, litWidth)
                defer rc.Close()
                b.Reset()
                n, err := io.Copy(&b, rc)
                if err != nil {
                        if err != tt.err {
                                t.Errorf("%s: io.Copy: %v want %v", tt.desc, err, tt.err)
                        }
                        continue
                }
                s := b.String()
                if s != tt.raw {
                        t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.desc, n, s, len(tt.raw), tt.raw)
                }
        }
}

func benchmarkDecoder(b *testing.B, n int) {
        b.StopTimer()
        b.SetBytes(int64(n))
        buf0, _ := ioutil.ReadFile("../testdata/e.txt")
        buf0 = buf0[:10000]
        compressed := new(bytes.Buffer)
        w := NewWriter(compressed, LSB, 8)
        for i := 0; i < n; i += len(buf0) {
                io.Copy(w, bytes.NewBuffer(buf0))
        }
        w.Close()
        buf1 := compressed.Bytes()
        buf0, compressed, w = nil, nil, nil
        runtime.GC()
        b.StartTimer()
        for i := 0; i < b.N; i++ {
                io.Copy(ioutil.Discard, NewReader(bytes.NewBuffer(buf1), LSB, 8))
        }
}

func BenchmarkDecoder1e4(b *testing.B) {
        benchmarkDecoder(b, 1e4)
}

func BenchmarkDecoder1e5(b *testing.B) {
        benchmarkDecoder(b, 1e5)
}

func BenchmarkDecoder1e6(b *testing.B) {
        benchmarkDecoder(b, 1e6)
}