/*  -*- C++ -*-
*  Copyright (C) 1998 <developer@mozilla.org>
*
*
*  Permission is hereby granted, free of charge, to any person obtaining
*  a copy of this software and associated documentation files (the
*  "Software"), to deal in the Software without restriction, including
*  without limitation the rights to use, copy, modify, merge, publish,
*  distribute, sublicense, and/or sell copies of the Software, and to
*  permit persons to whom the Software is furnished to do so, subject to
*  the following conditions:
*
*  The above copyright notice and this permission notice shall be included
*  in all copies or substantial portions of the Software.
*
*  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
*  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
*  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
*  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
*  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
*  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
*  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#include "nsLatin1Prober.h"
#include <stdio.h>
#include <stdlib.h>

#define UDF    0        // undefined
#define OTH    1        //other
#define ASC    2        // ascii capital letter
#define ASS    3        // ascii small letter
#define ACV    4        // accent capital vowel
#define ACO    5        // accent capital other
#define ASV    6        // accent small vowel
#define ASO    7        // accent small other
#define CLASS_NUM   8    // total classes

namespace kencodingprober
{
static const unsigned char Latin1_CharToClass[] = {
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 00 - 07
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 08 - 0F
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 10 - 17
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 18 - 1F
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 20 - 27
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 28 - 2F
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 30 - 37
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 38 - 3F
    OTH, ASC, ASC, ASC, ASC, ASC, ASC, ASC,   // 40 - 47
    ASC, ASC, ASC, ASC, ASC, ASC, ASC, ASC,   // 48 - 4F
    ASC, ASC, ASC, ASC, ASC, ASC, ASC, ASC,   // 50 - 57
    ASC, ASC, ASC, OTH, OTH, OTH, OTH, OTH,   // 58 - 5F
    OTH, ASS, ASS, ASS, ASS, ASS, ASS, ASS,   // 60 - 67
    ASS, ASS, ASS, ASS, ASS, ASS, ASS, ASS,   // 68 - 6F
    ASS, ASS, ASS, ASS, ASS, ASS, ASS, ASS,   // 70 - 77
    ASS, ASS, ASS, OTH, OTH, OTH, OTH, OTH,   // 78 - 7F
    OTH, UDF, OTH, ASO, OTH, OTH, OTH, OTH,   // 80 - 87
    OTH, OTH, ACO, OTH, ACO, UDF, ACO, UDF,   // 88 - 8F
    UDF, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // 90 - 97
    OTH, OTH, ASO, OTH, ASO, UDF, ASO, ACO,   // 98 - 9F
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // A0 - A7
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // A8 - AF
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // B0 - B7
    OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH,   // B8 - BF
    ACV, ACV, ACV, ACV, ACV, ACV, ACO, ACO,   // C0 - C7
    ACV, ACV, ACV, ACV, ACV, ACV, ACV, ACV,   // C8 - CF
    ACO, ACO, ACV, ACV, ACV, ACV, ACV, OTH,   // D0 - D7
    ACV, ACV, ACV, ACV, ACV, ACO, ACO, ACO,   // D8 - DF
    ASV, ASV, ASV, ASV, ASV, ASV, ASO, ASO,   // E0 - E7
    ASV, ASV, ASV, ASV, ASV, ASV, ASV, ASV,   // E8 - EF
    ASO, ASO, ASV, ASV, ASV, ASV, ASV, OTH,   // F0 - F7
    ASV, ASV, ASV, ASV, ASV, ASO, ASO, ASO,   // F8 - FF
};

/* 0 : illegal
   1 : very unlikely
   2 : normal
   3 : very likely
*/
static const unsigned char Latin1ClassModel[] = {
    /*      UDF OTH ASC ASS ACV ACO ASV ASO  */
    /*UDF*/  0,  0,  0,  0,  0,  0,  0,  0,
    /*OTH*/  0,  3,  3,  3,  3,  3,  3,  3,
    /*ASC*/  0,  3,  3,  3,  3,  3,  3,  3,
    /*ASS*/  0,  3,  3,  3,  1,  1,  3,  3,
    /*ACV*/  0,  3,  3,  3,  1,  2,  1,  2,
    /*ACO*/  0,  3,  3,  3,  3,  3,  3,  3,
    /*ASV*/  0,  3,  1,  3,  1,  1,  1,  3,
    /*ASO*/  0,  3,  1,  3,  1,  1,  3,  3,
};

void  nsLatin1Prober::Reset(void)
{
    mState = eDetecting;
    mLastCharClass = OTH;
    for (int i = 0; i < FREQ_CAT_NUM; i++) {
        mFreqCounter[i] = 0;
    }
}

nsProbingState nsLatin1Prober::HandleData(const char *aBuf, unsigned int aLen)
{
    char *newBuf1 = 0;
    unsigned int newLen1 = 0;

    if (!FilterWithEnglishLetters(aBuf, aLen, &newBuf1, newLen1)) {
        newBuf1 = (char *)aBuf;
        newLen1 = aLen;
    }

    unsigned char charClass;
    unsigned char freq;
    for (unsigned int i = 0; i < newLen1; i++) {
        charClass = Latin1_CharToClass[(unsigned char)newBuf1[i]];
        freq = Latin1ClassModel[mLastCharClass * CLASS_NUM + charClass];
        if (freq == 0) {
            mState = eNotMe;
            break;
        }
        mFreqCounter[freq]++;
        mLastCharClass = charClass;
    }

    if (newBuf1 != aBuf) {
        free(newBuf1);
    }

    return mState;
}

float nsLatin1Prober::GetConfidence(void)
{
    if (mState == eNotMe) {
        return 0.01f;
    }

    float confidence;
    unsigned int total = 0;
    for (int i = 0; i < FREQ_CAT_NUM; i++) {
        total += mFreqCounter[i];
    }

    if (!total) {
        confidence = 0.0f;
    } else {
        confidence = mFreqCounter[3] * 1.0f / total;
        confidence -= mFreqCounter[1] * 20.0f / total;
    }

    if (confidence < 0.0f) {
        confidence = 0.0f;
    }

    // lower the confidence of latin1 so that other more accurate detector
    // can take priority.
    confidence *= 0.50f;

    return confidence;
}

#ifdef DEBUG_PROBE
void  nsLatin1Prober::DumpStatus()
{
    printf(" Latin1Prober: %1.3f [%s]\r\n", GetConfidence(), GetCharSetName());
}
#endif
}

