// © 2016 and later: Unicode, Inc. and others.

// License & terms of use: http://www.unicode.org/copyright.html

/*

 **********************************************************************

 *   Copyright (C) 2005-2016, International Business Machines

 *   Corporation and others.  All Rights Reserved.

 **********************************************************************

 */

#include "unicode/utypes.h"

#if !UCONFIG_NO_CONVERSION

#include "cmemory.h"

#include "cstring.h"

#include "csr2022.h"

#include "csmatch.h"

U_NAMESPACE_BEGIN

/**

 * Matching function shared among the 2022 detectors JP, CN and KR

 * Counts up the number of legal and unrecognized escape sequences in

 * the sample of text, and computes a score based on the total number &

 * the proportion that fit the encoding.

 * 

 * 

 * @param text the byte buffer containing text to analyse

 * @param textLen  the size of the text in the byte.

 * @param escapeSequences the byte escape sequences to test for.

 * @return match quality, in the range of 0-100.

 */

int32_t CharsetRecog_2022::match_2022(const uint8_t *text, int32_t textLen, const uint8_t escapeSequences[][5], int32_t escapeSequences_length) const

{

    int32_t i, j;

    int32_t escN;

    int32_t hits   = 0;

    int32_t misses = 0;

    int32_t shifts = 0;

    int32_t quality;

    i = 0;

    while(i < textLen) {

        if(text[i] == 0x1B) {

            escN = 0;

            while(escN < escapeSequences_length) {

                const uint8_t *seq = escapeSequences[escN];

                int32_t seq_length = (int32_t)uprv_strlen((const char *) seq);

                if (textLen-i >= seq_length) {

                    j = 1;

                    while(j < seq_length) {

                        if(seq[j] != text[i+j]) {

                            goto checkEscapes;

                        }

                        j += 1;

                    }

                    hits += 1;

                    i += seq_length-1;

                    goto scanInput;

                }

                // else we ran out of string to compare this time.

checkEscapes:

                escN += 1;

            }

            misses += 1;

        }

        if( text[i]== 0x0e || text[i] == 0x0f){

            shifts += 1;

        }

scanInput:

        i += 1;

    }

    if (hits == 0) {

        return 0;

    }

    //

    // Initial quality is based on relative proportion of recongized vs.

    //   unrecognized escape sequences. 

    //   All good:  quality = 100;

    //   half or less good: quality = 0;

    //   linear inbetween.

    quality = (100*hits - 100*misses) / (hits + misses);

    // Back off quality if there were too few escape sequences seen.

    //   Include shifts in this computation, so that KR does not get penalized

    //   for having only a single Escape sequence, but many shifts.

    if (hits+shifts < 5) {

        quality -= (5-(hits+shifts))*10;

    }

    if (quality < 0) {

        quality = 0;

    }

    return quality;

}

static const uint8_t escapeSequences_2022JP[][5] = {

    {0x1b, 0x24, 0x28, 0x43, 0x00},   // KS X 1001:1992

    {0x1b, 0x24, 0x28, 0x44, 0x00},   // JIS X 212-1990

    {0x1b, 0x24, 0x40, 0x00, 0x00},   // JIS C 6226-1978

    {0x1b, 0x24, 0x41, 0x00, 0x00},   // GB 2312-80

    {0x1b, 0x24, 0x42, 0x00, 0x00},   // JIS X 208-1983

    {0x1b, 0x26, 0x40, 0x00, 0x00},   // JIS X 208 1990, 1997

    {0x1b, 0x28, 0x42, 0x00, 0x00},   // ASCII

    {0x1b, 0x28, 0x48, 0x00, 0x00},   // JIS-Roman

    {0x1b, 0x28, 0x49, 0x00, 0x00},   // Half-width katakana

    {0x1b, 0x28, 0x4a, 0x00, 0x00},   // JIS-Roman

    {0x1b, 0x2e, 0x41, 0x00, 0x00},   // ISO 8859-1

    {0x1b, 0x2e, 0x46, 0x00, 0x00}    // ISO 8859-7

};

#if !UCONFIG_ONLY_HTML_CONVERSION

static const uint8_t escapeSequences_2022KR[][5] = {

    {0x1b, 0x24, 0x29, 0x43, 0x00}   

};

static const uint8_t escapeSequences_2022CN[][5] = {

    {0x1b, 0x24, 0x29, 0x41, 0x00},   // GB 2312-80

    {0x1b, 0x24, 0x29, 0x47, 0x00},   // CNS 11643-1992 Plane 1

    {0x1b, 0x24, 0x2A, 0x48, 0x00},   // CNS 11643-1992 Plane 2

    {0x1b, 0x24, 0x29, 0x45, 0x00},   // ISO-IR-165

    {0x1b, 0x24, 0x2B, 0x49, 0x00},   // CNS 11643-1992 Plane 3

    {0x1b, 0x24, 0x2B, 0x4A, 0x00},   // CNS 11643-1992 Plane 4

    {0x1b, 0x24, 0x2B, 0x4B, 0x00},   // CNS 11643-1992 Plane 5

    {0x1b, 0x24, 0x2B, 0x4C, 0x00},   // CNS 11643-1992 Plane 6

    {0x1b, 0x24, 0x2B, 0x4D, 0x00},   // CNS 11643-1992 Plane 7

    {0x1b, 0x4e, 0x00, 0x00, 0x00},   // SS2

    {0x1b, 0x4f, 0x00, 0x00, 0x00},   // SS3

};

#endif

CharsetRecog_2022JP::~CharsetRecog_2022JP() {}

const char *CharsetRecog_2022JP::getName() const {

    return "ISO-2022-JP";

}

UBool CharsetRecog_2022JP::match(InputText *textIn, CharsetMatch *results) const {

    int32_t confidence = match_2022(textIn->fInputBytes, 

                                    textIn->fInputLen, 

                                    escapeSequences_2022JP, 

                                    UPRV_LENGTHOF(escapeSequences_2022JP));

    results->set(textIn, this, confidence);

    return (confidence > 0);

}

#if !UCONFIG_ONLY_HTML_CONVERSION

CharsetRecog_2022KR::~CharsetRecog_2022KR() {}

const char *CharsetRecog_2022KR::getName() const {

    return "ISO-2022-KR";

}

UBool CharsetRecog_2022KR::match(InputText *textIn, CharsetMatch *results) const {

    int32_t confidence = match_2022(textIn->fInputBytes, 

                                    textIn->fInputLen, 

                                    escapeSequences_2022KR, 

                                    UPRV_LENGTHOF(escapeSequences_2022KR));

    results->set(textIn, this, confidence);

    return (confidence > 0);

}

CharsetRecog_2022CN::~CharsetRecog_2022CN() {}

const char *CharsetRecog_2022CN::getName() const {

    return "ISO-2022-CN";

}

UBool CharsetRecog_2022CN::match(InputText *textIn, CharsetMatch *results) const {

    int32_t confidence = match_2022(textIn->fInputBytes,

                                    textIn->fInputLen,

                                    escapeSequences_2022CN,

                                    UPRV_LENGTHOF(escapeSequences_2022CN));

    results->set(textIn, this, confidence);

    return (confidence > 0);

}

#endif

CharsetRecog_2022::~CharsetRecog_2022() {

    // nothing to do

}

U_NAMESPACE_END

#endif