/* Copyright 2014 Adobe Systems Incorporated (http://www.adobe.com/). All Rights Reserved.
   This software is licensed as OpenSource, under the Apache License, Version 2.0.
   This license is available at: http://opensource.org/licenses/Apache-2.0. */
/***********************************************************************/

#include "cffwrite_encoding.h"

#include <string.h>
#include <stdlib.h>

typedef struct /* Supplementary encoding */
{
    unsigned char code;
    SID sid;
} SupCode;
#define SUP_CODE_SIZE (1 + 2)

/* Declarations used for determining sizes and for format documentation */
typedef struct {
    unsigned char format;
    unsigned char nCodes;
    unsigned char *code; /* [nCodes] */
} Format0;
#define FORMAT0_SIZE(n) (2 * 1 + (n)*1)

typedef struct {
    unsigned char first; /* First code in range */
    unsigned char nLeft; /* Number codes left in range (excluding first) */
} Range;
#define RANGE_SIZE (2 * 1)

typedef struct {
    unsigned char format;
    unsigned char nRanges;
    Range *range; /* [nRanges] */
} Format1;
#define FORMAT1_SIZE(n) (2 * 1 + (n)*RANGE_SIZE)

/* Supplemental encodings */
typedef struct {
    unsigned char nSups;
    SupCode *supplement;
} Supplemental;
#define SUPPLEMENTAL_SIZE(n) (1 + (n)*SUP_CODE_SIZE)

typedef struct {
    dnaDCL(unsigned char, codes); /* Character codes */
    dnaDCL(SupCode, supcodes);    /* Supplementary codes */
    unsigned char nRanges;        /* # code ranges */
    unsigned char format;         /* Selected format */
    Offset offset;                /* Offset relative to first encoding */
} Encoding;

/* Predefined encodings */
static const unsigned char stdenc[] = {
#include "stdenc0.h" /* 0 Standard */
};
static const unsigned char exenc[] = {
#include "exenc0.h" /* 1 Expert (also used with expert subset fonts) */
};

static const struct {
    short cnt;
    const unsigned char *array;
} predefs[] = {
    {ARRAY_LEN(stdenc), stdenc},
    {ARRAY_LEN(exenc), exenc},
};
#define PREDEF_CNT ARRAY_LEN(predefs)

/* ----------------------------- Module Context ---------------------------- */

struct encodingCtx_ {
    dnaDCL(Encoding, encodings);
    Encoding *_new; /* Encoding being added */
    cfwCtx g;       /* Package context */
};

/* Initialize encoding. */
static void initEncoding(void *ctx, long cnt, Encoding *encoding) {
    cfwCtx g = (cfwCtx)ctx;
    while (cnt--) {
        dnaINIT(g->ctx.dnaSafe, encoding->codes, 256, 256);
        dnaINIT(g->ctx.dnaSafe, encoding->supcodes, 5, 10);
        encoding++;
    }
}

/* Initialize module. */
void cfwEncodingNew(cfwCtx g) {
    encodingCtx h = (encodingCtx)cfwMemNew(g, sizeof(struct encodingCtx_));

    /* Link contexts */
    h->g = g;
    g->ctx.encoding = h;

    dnaINIT(g->ctx.dnaSafe, h->encodings, 1, 10);
    h->encodings.func = initEncoding;
}

/* Prepare module for reuse. */
void cfwEncodingReuse(cfwCtx g) {
    encodingCtx h = g->ctx.encoding;
    h->encodings.cnt = 0;
}

/* Free resources */
void cfwEncodingFree(cfwCtx g) {
    encodingCtx h = g->ctx.encoding;
    int i;

    if (h == NULL) {
        return;
    }

    for (i = 0; i < h->encodings.size; i++) {
        Encoding *encoding = &h->encodings.array[i];
        dnaFREE(encoding->codes);
        dnaFREE(encoding->supcodes);
    }
    dnaFREE(h->encodings);

    cfwMemFree(g, h);
    g->ctx.encoding = NULL;
}

/* Get pre-defined encoding identified by "id" (beginning at 0). An array of
   "cnt" elements is returned that maps an SID to a character code or 0 if
   unencoded. A return of NULL indicates no encoding is pre-defined for the
   specified id. */
const unsigned char *cfwEncodingGetPredef(int id, int *cnt) {
    if (id >= (int)PREDEF_CNT) {
        return NULL;
    }

    *cnt = predefs[id].cnt;
    return predefs[id].array;
}

/* Begin new encoding. */
void cfwEncodingBeg(cfwCtx g) {
    encodingCtx h = g->ctx.encoding;
    h->_new = dnaNEXT(h->encodings);
    h->_new->codes.cnt = 0;
    h->_new->supcodes.cnt = 0;
}

/* Add code point to encoding. */
void cfwEncodingAddCode(cfwCtx g, unsigned char code) {
    encodingCtx h = g->ctx.encoding;
    *dnaNEXT(h->_new->codes) = code;
}

/* Add supplementary code point to encoding. */
void cfwEncodingAddSupCode(cfwCtx g, unsigned char code, SID sid) {
    encodingCtx h = g->ctx.encoding;
    SupCode *sup = dnaNEXT(h->_new->supcodes);
    sup->code = code;
    sup->sid = sid;
}

/* Compare supplementary encodings. */
static int CTL_CDECL cmpSupCodes(const void *first, const void *second) {
    SupCode *a = (SupCode *)first;
    SupCode *b = (SupCode *)second;
    if (a->code < b->code) {
        return -1;
    } else if (a->code > b->code) {
        return 1;
    } else if (a->sid < b->sid) {
        return -1;
    } else if (a->sid > b->sid) {
        return 1;
    } else {
        return 0;
    }
}

/* End code point addition and check for duplicate encoding. */
int cfwEncodingEnd(cfwCtx g) {
    encodingCtx h = g->ctx.encoding;
    int i;

    /* Sort supplementary encoding by code */
    if (h->_new->supcodes.cnt > 0) {
        qsort(h->_new->supcodes.array, h->_new->supcodes.cnt, sizeof(SupCode),
              cmpSupCodes);
    }

    for (i = 0; i < h->encodings.cnt - 1; i++) {
        Encoding *encoding = &h->encodings.array[i];

        if (h->_new->codes.cnt == encoding->codes.cnt &&
            h->_new->supcodes.cnt == encoding->supcodes.cnt &&
            memcmp(h->_new->codes.array,
                   encoding->codes.array,
                   h->_new->codes.cnt) == 0 &&
            memcmp(h->_new->supcodes.array,
                   encoding->supcodes.array,
                   h->_new->supcodes.cnt) == 0) {
            /* Found match; remove new encoding from list */
            h->encodings.cnt--;
            return PREDEF_CNT + i;
        }
    }

    /* No match found; leave encoding in list */
    return PREDEF_CNT + h->encodings.cnt - 1;
}

/* Fill encodings and return total size of all encodings. */
long cfwEncodingFill(cfwCtx g) {
    encodingCtx h = g->ctx.encoding;
    int i;
    Offset offset;

    offset = 0;
    for (i = 0; i < h->encodings.cnt; i++) {
        int j;
        Encoding *encoding = &h->encodings.array[i];
        long size0;
        long size1;

        /* Count ranges */
        encoding->nRanges = 1;
        for (j = 1; j < encoding->codes.cnt; j++) {
            if (encoding->codes.array[j - 1] + 1 != encoding->codes.array[j]) {
                encoding->nRanges++;
            }
        }

        encoding->offset = offset;

        /* Save format and offset */
        size0 = FORMAT0_SIZE(encoding->codes.cnt);
        size1 = FORMAT1_SIZE(encoding->nRanges);
        if (size0 < size1) {
            /* Select format 0 */
            offset += size0;
            encoding->format = 0;
        } else {
            /* Select format 1 */
            offset += size1;
            encoding->format = 1;
        }
        if (encoding->supcodes.cnt > 0) {
            encoding->format |= 0x80;
            offset += SUPPLEMENTAL_SIZE(encoding->supcodes.cnt);
        }
    }
    return offset;
}

/* Write encodings. */
void cfwEncodingWrite(cfwCtx g) {
    encodingCtx h = g->ctx.encoding;
    int i;

    /* Write non-standard encodings */
    for (i = 0; i < h->encodings.cnt; i++) {
        int j;
        Encoding *encoding = &h->encodings.array[i];

        cfwWrite1(g, encoding->format);
        switch (encoding->format & 0x7f) {
            case 0:
                /* Write format 0 */
                cfwWrite1(g, (unsigned char)encoding->codes.cnt);
                cfwWrite(g, encoding->codes.cnt, (char *)encoding->codes.array);
                break;

            case 1: {
                /* Write format 1 */
                unsigned char nLeft = 0;

                cfwWrite1(g, encoding->nRanges);
                cfwWrite1(g, encoding->codes.array[0]);
                for (j = 1; j < encoding->codes.cnt; j++) {
                    if (encoding->codes.array[j - 1] + 1 !=
                            encoding->codes.array[j] ||
                        nLeft == 255) {
                        cfwWrite1(g, nLeft);
                        cfwWrite1(g, encoding->codes.array[j]);
                        nLeft = 0;
                    } else {
                        nLeft++;
                    }
                }
                cfwWrite1(g, nLeft);
            } break;
        }
        if (encoding->format & 0x80) {
            cfwWrite1(g, (unsigned char)encoding->supcodes.cnt);
            for (j = 0; j < encoding->supcodes.cnt; j++) {
                SupCode *supplement = &encoding->supcodes.array[j];
                cfwWrite1(g, supplement->code);
                cfwWrite2(g, supplement->sid);
            }
        }
    }
}

/* Get absolute encoding offset. */
Offset cfwEncodingGetOffset(cfwCtx g, int iEncoding, Offset base) {
    encodingCtx h = g->ctx.encoding;
    return (iEncoding < (int)PREDEF_CNT) ? iEncoding : base + h->encodings.array[iEncoding - PREDEF_CNT].offset;
}