/**
 * Convert a file of UTF-8 to Windows-1252.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>

static int tolerance = 100;
static char * defaultValue;
static char ochar[1153];

int getUnicodePoint( FILE * infp ) {
    int c;
    int answer;
    int mask;
    int topmask;
    int bytes;

    c = fgetc( infp );
    answer = c;
    if ( EOF != c && 0x80 & c ) {
        bytes = 0;
        topmask = 0xff;
        for ( mask = 0x80; c & mask; mask >>= 1 ) {
            topmask >>= 1;
            bytes++;
        }
        bytes--;
        answer = ( c & topmask ) << ( bytes * 6 );
        while ( 0 < bytes ) {
            c = fgetc( infp );
            bytes--;
            answer += ( c & 0x3f ) << ( bytes * 6 );
        }
        assert( EOF != answer );
    }
    return answer;
}

void replace( int c ) {
    fprintf( stderr,
        "Unicode code point %d has no equivalent in ISO-8859-1.\n", c );
    if ( 0 == tolerance ) {
        fprintf( stderr, "Too many unmappable characters. Quitting.\n" );
        exit( 1 );
    }
    tolerance--;
    printf( defaultValue, c );
}

void putUnicodePoint( int c ) {
    if ( c < 128 ) {
        putchar( c );
    }
    else if ( c < 1000 ) {
        putchar( ochar[c - 128] );
    }
    else {
        putchar( ochar[c - 7200 - 128] );
    }
}

void doFiles( int argc, char **argv ) {

    FILE *infp;
    char *infile;
    int c;

    while ( --argc > 0 ) {
        infile = *++argv;

        if ( 0 == strcmp( infile, "-" ) ) {
            infp = stdin;
        }
        /* Must open input in binary mode so we can catch chars with high bit set. */
        else if ( ( infp = fopen( infile, "rb" ) ) == NULL ) {
            fprintf( stderr, "Unable to open input file \"%s\".\n", infile );
            continue;
        }
        while ( EOF != ( c = getUnicodePoint( infp ) ) ) {
            putUnicodePoint( c );
        }
    }

}

int main( int argc, char **argv ) {

    extern int optind;
    int i, j, c;
    char * oneName[2];

    for ( i = 0; i < 1154; i++ ) {
        ochar[i] = '?';
    }
    ochar[32] = 0xa0;
    ochar[33] = 0xa1;
    ochar[34] = 0xa2;
    ochar[35] = 0xa3;
    ochar[36] = 0xa4;
    ochar[37] = 0xa5;
    ochar[38] = 0xa6;
    ochar[39] = 0xa7;
    ochar[40] = 0xa8;
    ochar[41] = 0xa9;
    ochar[42] = 0xaa;
    ochar[43] = 0xab;
    ochar[44] = 0xac;
    ochar[45] = 0xad;
    ochar[46] = 0xae;
    ochar[47] = 0xaf;
    ochar[48] = 0xb0;
    ochar[49] = 0xb1;
    ochar[50] = 0xb2;
    ochar[51] = 0xb3;
    ochar[52] = 0xb4;
    ochar[53] = 0xb5;
    ochar[54] = 0xb6;
    ochar[55] = 0xb7;
    ochar[56] = 0xb8;
    ochar[57] = 0xb9;
    ochar[58] = 0xba;
    ochar[59] = 0xbb;
    ochar[60] = 0xbc;
    ochar[61] = 0xbd;
    ochar[62] = 0xbe;
    ochar[63] = 0xbf;
    ochar[64] = 0xc0;
    ochar[65] = 0xc1;
    ochar[66] = 0xc2;
    ochar[67] = 0xc3;
    ochar[68] = 0xc4;
    ochar[69] = 0xc5;
    ochar[70] = 0xc6;
    ochar[71] = 0xc7;
    ochar[72] = 0xc8;
    ochar[73] = 0xc9;
    ochar[74] = 0xca;
    ochar[75] = 0xcb;
    ochar[76] = 0xcc;
    ochar[77] = 0xcd;
    ochar[78] = 0xce;
    ochar[79] = 0xcf;
    ochar[80] = 0xd0;
    ochar[81] = 0xd1;
    ochar[82] = 0xd2;
    ochar[83] = 0xd3;
    ochar[84] = 0xd4;
    ochar[85] = 0xd5;
    ochar[86] = 0xd6;
    ochar[87] = 0xd7;
    ochar[88] = 0xd8;
    ochar[89] = 0xd9;
    ochar[90] = 0xda;
    ochar[91] = 0xdb;
    ochar[92] = 0xdc;
    ochar[93] = 0xdd;
    ochar[94] = 0xde;
    ochar[95] = 0xdf;
    ochar[96] = 0xe0;
    ochar[97] = 0xe1;
    ochar[98] = 0xe2;
    ochar[99] = 0xe3;
    ochar[100] = 0xe4;
    ochar[101] = 0xe5;
    ochar[102] = 0xe6;
    ochar[103] = 0xe7;
    ochar[104] = 0xe8;
    ochar[105] = 0xe9;
    ochar[106] = 0xea;
    ochar[107] = 0xeb;
    ochar[108] = 0xec;
    ochar[109] = 0xed;
    ochar[110] = 0xee;
    ochar[111] = 0xef;
    ochar[112] = 0xf0;
    ochar[113] = 0xf1;
    ochar[114] = 0xf2;
    ochar[115] = 0xf3;
    ochar[116] = 0xf4;
    ochar[117] = 0xf5;
    ochar[118] = 0xf6;
    ochar[119] = 0xf7;
    ochar[120] = 0xf8;
    ochar[121] = 0xf9;
    ochar[122] = 0xfa;
    ochar[123] = 0xfb;
    ochar[124] = 0xfc;
    ochar[125] = 0xfd;
    ochar[126] = 0xfe;
    ochar[127] = 0xff;
    ochar[210] = 0x8c;
    ochar[211] = 0x9c;
    ochar[224] = 0x8a;
    ochar[225] = 0x9a;
    ochar[248] = 0x9f;
    ochar[253] = 0x8e;
    ochar[254] = 0x9e;
    ochar[274] = 0x83;
    ochar[582] = 0x88;
    ochar[604] = 0x98;
    ochar[883] = 0x96;
    ochar[884] = 0x97;
    ochar[888] = 0x91;
    ochar[889] = 0x92;
    ochar[890] = 0x82;
    ochar[892] = 0x93;
    ochar[893] = 0x94;
    ochar[894] = 0x84;
    ochar[896] = 0x86;
    ochar[897] = 0x87;
    ochar[898] = 0x95;
    ochar[902] = 0x85;
    ochar[912] = 0x89;
    ochar[921] = 0x8b;
    ochar[922] = 0x9b;
    ochar[1036] = 0x80;
    ochar[1154] = 0x99;

    defaultValue = "?";

    while ( -1 != ( c = getopt( argc, argv, "t:d:" ) ) ) {
        switch (c) {
        case 't':
            fprintf( stderr, "Tolerance given as %s.\n", optarg );
            tolerance = atoi(optarg);
            break;
        case 'd':
            defaultValue = optarg;
            break;
        default:
            fprintf( stderr, "usage: utf2iso [-t n] [-d s] [files]\n" );
            fprintf( stderr, " where n is how many errors to tolerate\n" );
            fprintf( stderr, " and s is a default string" );
            fprintf( stderr, " for unmappable chars.\n" );
            fprintf( stderr, " s can contain something like %%d" );
            fprintf( stderr, " or be empty.\n" );
            exit( 1 );
        }
    }
    i = 1;
    j = optind;
    while ( j < argc ) {
        argv[i++] = argv[j++];
    }
    argc -= ( j - i );

    if ( argc < 2 ) {
        oneName[0] = argv[0];
        oneName[1] = "-";
        doFiles( 2, oneName );
    }
    else {
        doFiles( argc, argv );
    }

    return 0;
}