/*
 * toucs.c - convert charsets to Unicode.
 */

#include "charset.h"
#include "internal.h"

struct unicode_emit_param {
    wchar_t *output;
    int outlen;
    const wchar_t *errstr;
    int errlen;
    int stopped;
};

static void unicode_emit(void *ctx, long int output)
{
    struct unicode_emit_param *param = (struct unicode_emit_param *)ctx;
    wchar_t outval;
    wchar_t const *p;
    int outlen;

    if (output == ERROR) {
        if (param->errstr) {
            p = param->errstr;
            outlen = param->errlen;
        } else {
            outval = 0xFFFD;           /* U+FFFD REPLACEMENT CHARACTER */
            p = &outval;
            outlen = 1;
        }
    } else {
        outval = output;
        p = &outval;
        outlen = 1;
    }

    if (param->outlen >= outlen) {
        while (outlen > 0) {
            *param->output++ = *p++;
            param->outlen--;
            outlen--;
        }
    } else {
        param->stopped = 1;
    }
}

int charset_to_unicode(const char **input, int *inlen,
                       wchar_t *output, int outlen,
                       int charset, charset_state *state,
                       const wchar_t *errstr, int errlen)
{
    charset_spec const *spec = charset_find_spec(charset);
    charset_state localstate;
    struct unicode_emit_param param;

    param.output = output;
    param.outlen = outlen;
    param.errstr = errstr;
    param.errlen = errlen;
    param.stopped = 0;

    if (!state) {
        localstate.s0 = 0;
    } else {
        localstate = *state;           /* structure copy */
    }

    while (*inlen > 0) {
        int lenbefore = param.output - output;
        spec->read(spec, (unsigned char)**input, &localstate,
                   unicode_emit, &param);
        if (param.stopped) {
            /*
             * The emit function has _tried_ to output some
             * characters, but ran up against the end of the
             * buffer. Leave immediately, and return what happened
             * _before_ attempting to process this character.
             */
            return lenbefore;
        }
        if (state)
            *state = localstate;   /* structure copy */
        (*input)++;
        (*inlen)--;
    }

    return param.output - output;
}
