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// Copyright 2009 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 flate

import (
        "bytes"
        "fmt"
        "io"
        "io/ioutil"
        "sync"
        "testing"
)

type deflateTest struct {
        in    []byte
        level int
        out   []byte
}

type deflateInflateTest struct {
        in []byte
}

type reverseBitsTest struct {
        in       uint16
        bitCount uint8
        out      uint16
}

var deflateTests = []*deflateTest{
        {[]byte{}, 0, []byte{1, 0, 0, 255, 255}},
        {[]byte{0x11}, -1, []byte{18, 4, 4, 0, 0, 255, 255}},
        {[]byte{0x11}, DefaultCompression, []byte{18, 4, 4, 0, 0, 255, 255}},
        {[]byte{0x11}, 4, []byte{18, 4, 4, 0, 0, 255, 255}},

        {[]byte{0x11}, 0, []byte{0, 1, 0, 254, 255, 17, 1, 0, 0, 255, 255}},
        {[]byte{0x11, 0x12}, 0, []byte{0, 2, 0, 253, 255, 17, 18, 1, 0, 0, 255, 255}},
        {[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 0,
                []byte{0, 8, 0, 247, 255, 17, 17, 17, 17, 17, 17, 17, 17, 1, 0, 0, 255, 255},
        },
        {[]byte{}, 1, []byte{1, 0, 0, 255, 255}},
        {[]byte{0x11}, 1, []byte{18, 4, 4, 0, 0, 255, 255}},
        {[]byte{0x11, 0x12}, 1, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
        {[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 1, []byte{18, 132, 2, 64, 0, 0, 0, 255, 255}},
        {[]byte{}, 9, []byte{1, 0, 0, 255, 255}},
        {[]byte{0x11}, 9, []byte{18, 4, 4, 0, 0, 255, 255}},
        {[]byte{0x11, 0x12}, 9, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
        {[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 9, []byte{18, 132, 2, 64, 0, 0, 0, 255, 255}},
}

var deflateInflateTests = []*deflateInflateTest{
        {[]byte{}},
        {[]byte{0x11}},
        {[]byte{0x11, 0x12}},
        {[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}},
        {[]byte{0x11, 0x10, 0x13, 0x41, 0x21, 0x21, 0x41, 0x13, 0x87, 0x78, 0x13}},
        {largeDataChunk()},
}

var reverseBitsTests = []*reverseBitsTest{
        {1, 1, 1},
        {1, 2, 2},
        {1, 3, 4},
        {1, 4, 8},
        {1, 5, 16},
        {17, 5, 17},
        {257, 9, 257},
        {29, 5, 23},
}

func largeDataChunk() []byte {
        result := make([]byte, 100000)
        for i := range result {
                result[i] = byte(i * i & 0xFF)
        }
        return result
}

func TestDeflate(t *testing.T) {
        for _, h := range deflateTests {
                var buf bytes.Buffer
                w := NewWriter(&buf, h.level)
                w.Write(h.in)
                w.Close()
                if !bytes.Equal(buf.Bytes(), h.out) {
                        t.Errorf("Deflate(%d, %x) = %x, want %x", h.level, h.in, buf.Bytes(), h.out)
                }
        }
}

type syncBuffer struct {
        buf    bytes.Buffer
        mu     sync.RWMutex
        closed bool
        ready  chan bool
}

func newSyncBuffer() *syncBuffer {
        return &syncBuffer{ready: make(chan bool, 1)}
}

func (b *syncBuffer) Read(p []byte) (n int, err error) {
        for {
                b.mu.RLock()
                n, err = b.buf.Read(p)
                b.mu.RUnlock()
                if n > 0 || b.closed {
                        return
                }
                <-b.ready
        }
        panic("unreachable")
}

func (b *syncBuffer) signal() {
        select {
        case b.ready <- true:
        default:
        }
}

func (b *syncBuffer) Write(p []byte) (n int, err error) {
        n, err = b.buf.Write(p)
        b.signal()
        return
}

func (b *syncBuffer) WriteMode() {
        b.mu.Lock()
}

func (b *syncBuffer) ReadMode() {
        b.mu.Unlock()
        b.signal()
}

func (b *syncBuffer) Close() error {
        b.closed = true
        b.signal()
        return nil
}

func testSync(t *testing.T, level int, input []byte, name string) {
        if len(input) == 0 {
                return
        }

        t.Logf("--testSync %d, %d, %s", level, len(input), name)
        buf := newSyncBuffer()
        buf1 := new(bytes.Buffer)
        buf.WriteMode()
        w := NewWriter(io.MultiWriter(buf, buf1), level)
        r := NewReader(buf)

        // Write half the input and read back.
        for i := 0; i < 2; i++ {
                var lo, hi int
                if i == 0 {
                        lo, hi = 0, (len(input)+1)/2
                } else {
                        lo, hi = (len(input)+1)/2, len(input)
                }
                t.Logf("#%d: write %d-%d", i, lo, hi)
                if _, err := w.Write(input[lo:hi]); err != nil {
                        t.Errorf("testSync: write: %v", err)
                        return
                }
                if i == 0 {
                        if err := w.Flush(); err != nil {
                                t.Errorf("testSync: flush: %v", err)
                                return
                        }
                } else {
                        if err := w.Close(); err != nil {
                                t.Errorf("testSync: close: %v", err)
                        }
                }
                buf.ReadMode()
                out := make([]byte, hi-lo+1)
                m, err := io.ReadAtLeast(r, out, hi-lo)
                t.Logf("#%d: read %d", i, m)
                if m != hi-lo || err != nil {
                        t.Errorf("testSync/%d (%d, %d, %s): read %d: %d, %v (%d left)", i, level, len(input), name, hi-lo, m, err, buf.buf.Len())
                        return
                }
                if !bytes.Equal(input[lo:hi], out[:hi-lo]) {
                        t.Errorf("testSync/%d: read wrong bytes: %x vs %x", i, input[lo:hi], out[:hi-lo])
                        return
                }
                // This test originally checked that after reading
                // the first half of the input, there was nothing left
                // in the read buffer (buf.buf.Len() != 0) but that is
                // not necessarily the case: the write Flush may emit
                // some extra framing bits that are not necessary
                // to process to obtain the first half of the uncompressed
                // data.  The test ran correctly most of the time, because
                // the background goroutine had usually read even
                // those extra bits by now, but it's not a useful thing to
                // check.
                buf.WriteMode()
        }
        buf.ReadMode()
        out := make([]byte, 10)
        if n, err := r.Read(out); n > 0 || err != io.EOF {
                t.Errorf("testSync (%d, %d, %s): final Read: %d, %v (hex: %x)", level, len(input), name, n, err, out[0:n])
        }
        if buf.buf.Len() != 0 {
                t.Errorf("testSync (%d, %d, %s): extra data at end", level, len(input), name)
        }
        r.Close()

        // stream should work for ordinary reader too
        r = NewReader(buf1)
        out, err := ioutil.ReadAll(r)
        if err != nil {
                t.Errorf("testSync: read: %s", err)
                return
        }
        r.Close()
        if !bytes.Equal(input, out) {
                t.Errorf("testSync: decompress(compress(data)) != data: level=%d input=%s", level, name)
        }
}

func testToFromWithLevel(t *testing.T, level int, input []byte, name string) error {
        return testToFromWithLevelAndLimit(t, level, input, name, -1)
}

func testToFromWithLevelAndLimit(t *testing.T, level int, input []byte, name string, limit int) error {
        var buffer bytes.Buffer
        w := NewWriter(&buffer, level)
        w.Write(input)
        w.Close()
        if limit > 0 && buffer.Len() > limit {
                t.Errorf("level: %d, len(compress(data)) = %d > limit = %d", level, buffer.Len(), limit)
        }
        r := NewReader(&buffer)
        out, err := ioutil.ReadAll(r)
        if err != nil {
                t.Errorf("read: %s", err)
                return err
        }
        r.Close()
        if !bytes.Equal(input, out) {
                t.Errorf("decompress(compress(data)) != data: level=%d input=%s", level, name)
        }

        testSync(t, level, input, name)
        return nil
}

func testToFromWithLimit(t *testing.T, input []byte, name string, limit [10]int) {
        for i := 0; i < 10; i++ {
                testToFromWithLevelAndLimit(t, i, input, name, limit[i])
        }
}

func testToFrom(t *testing.T, input []byte, name string) {
        testToFromWithLimit(t, input, name, [10]int{})
}

func TestDeflateInflate(t *testing.T) {
        for i, h := range deflateInflateTests {
                testToFrom(t, h.in, fmt.Sprintf("#%d", i))
        }
}

func TestReverseBits(t *testing.T) {
        for _, h := range reverseBitsTests {
                if v := reverseBits(h.in, h.bitCount); v != h.out {
                        t.Errorf("reverseBits(%v,%v) = %v, want %v",
                                h.in, h.bitCount, v, h.out)
                }
        }
}

type deflateInflateStringTest struct {
        filename string
        label    string
        limit    [10]int
}

var deflateInflateStringTests = []deflateInflateStringTest{
        {
                "../testdata/e.txt",
                "2.718281828...",
                [...]int{10013, 5065, 5096, 5115, 5093, 5079, 5079, 5079, 5079, 5079},
        },
        {
                "../testdata/Mark.Twain-Tom.Sawyer.txt",
                "Mark.Twain-Tom.Sawyer",
                [...]int{407330, 187598, 180361, 172974, 169160, 163476, 160936, 160506, 160295, 160295},
        },
}

func TestDeflateInflateString(t *testing.T) {
        for _, test := range deflateInflateStringTests {
                gold, err := ioutil.ReadFile(test.filename)
                if err != nil {
                        t.Error(err)
                }
                testToFromWithLimit(t, gold, test.label, test.limit)
        }
}

func TestReaderDict(t *testing.T) {
        const (
                dict = "hello world"
                text = "hello again world"
        )
        var b bytes.Buffer
        w := NewWriter(&b, 5)
        w.Write([]byte(dict))
        w.Flush()
        b.Reset()
        w.Write([]byte(text))
        w.Close()

        r := NewReaderDict(&b, []byte(dict))
        data, err := ioutil.ReadAll(r)
        if err != nil {
                t.Fatal(err)
        }
        if string(data) != "hello again world" {
                t.Fatalf("read returned %q want %q", string(data), text)
        }
}

func TestWriterDict(t *testing.T) {
        const (
                dict = "hello world"
                text = "hello again world"
        )
        var b bytes.Buffer
        w := NewWriter(&b, 5)
        w.Write([]byte(dict))
        w.Flush()
        b.Reset()
        w.Write([]byte(text))
        w.Close()

        var b1 bytes.Buffer
        w = NewWriterDict(&b1, 5, []byte(dict))
        w.Write([]byte(text))
        w.Close()

        if !bytes.Equal(b1.Bytes(), b.Bytes()) {
                t.Fatalf("writer wrote %q want %q", b1.Bytes(), b.Bytes())
        }
}

// See http://code.google.com/p/go/issues/detail?id=2508
func TestRegression2508(t *testing.T) {
        w := NewWriter(ioutil.Discard, 1)
        buf := make([]byte, 1024)
        for i := 0; i < 131072; i++ {
                if _, err := w.Write(buf); err != nil {
                        t.Fatalf("writer failed: %v", err)
                }
        }
        w.Close()
}