#include "moar.h"

/* Decodes the specified number of bytes of ASCII into an NFG string, creating

 * a result of the specified type. The type must have the MVMString REPR. */

MVMString * MVM_string_ascii_decode(MVMThreadContext *tc, const MVMObject *result_type, const char *ascii, size_t bytes) {

    MVMString *result = (MVMString *)REPR(result_type)->allocate(tc, STABLE(result_type));

    size_t i, result_graphs;

    result->body.storage_type    = MVM_STRING_GRAPHEME_32;

    result->body.storage.blob_32 = MVM_malloc(sizeof(MVMGrapheme32) * bytes);

    result_graphs = 0;

    for (i = 0; i < bytes; i++) {

        if (ascii[i] == '\r' && i + 1 < bytes && ascii[i + 1] == '\n') {

            result->body.storage.blob_32[result_graphs++] = MVM_nfg_crlf_grapheme(tc);

            i++;

        }

        else if (ascii[i] >= 0) {

            result->body.storage.blob_32[result_graphs++] = ascii[i];

        }

        else {

            MVM_exception_throw_adhoc(tc,

                "Will not decode invalid ASCII (code point > 127 found)");

        }

    }

    result->body.num_graphs = result_graphs;

    return result;

}

/* Decodes a NULL-terminated ASCII string into an NFG string, creating

 * a result of the specified type. The type must have the MVMString REPR. */

MVMString * MVM_string_ascii_decode_nt(MVMThreadContext *tc, const MVMObject *result_type, const char *ascii) {

    return MVM_string_ascii_decode(tc, result_type, ascii, strlen(ascii));

}

/* Decodes using a decodestream. Decodes as far as it can with the input

 * buffers, or until a stopper is reached. */

MVMuint32 MVM_string_ascii_decodestream(MVMThreadContext *tc, MVMDecodeStream *ds,

                                   const MVMint32 *stopper_chars,

                                   MVMDecodeStreamSeparators *seps) {

    MVMint32              count = 0, total = 0;

    MVMint32              bufsize;

    MVMGrapheme32        *buffer;

    MVMDecodeStreamBytes *cur_bytes;

    MVMDecodeStreamBytes *last_accept_bytes = ds->bytes_head;

    MVMint32 last_accept_pos, last_was_cr;

    MVMuint32 reached_stopper;

    /* If there's no buffers, we're done. */

    if (!ds->bytes_head)

        return 0;

    last_accept_pos = ds->bytes_head_pos;

    /* If we're asked for zero chars, also done. */

    if (stopper_chars && *stopper_chars == 0)

        return 1;

    /* Take length of head buffer as initial guess. */

    bufsize = ds->bytes_head->length;

    buffer = MVM_malloc(bufsize * sizeof(MVMGrapheme32));

    /* Decode each of the buffers. */

    cur_bytes = ds->bytes_head;

    last_was_cr = 0;

    reached_stopper = 0;

    while (cur_bytes) {

        /* Process this buffer. */

        MVMint32  pos   = cur_bytes == ds->bytes_head ? ds->bytes_head_pos : 0;

        char     *bytes = cur_bytes->bytes;

        while (pos < cur_bytes->length) {

            MVMCodepoint codepoint = bytes[pos++];

            MVMGrapheme32 graph;

            if (codepoint > 127)

                MVM_exception_throw_adhoc(tc,

                    "Will not decode invalid ASCII (code point > 127 found)");

            if (last_was_cr) {

                if (codepoint == '\n') {

                    graph = MVM_nfg_crlf_grapheme(tc);

                }

                else {

                    graph = '\r';

                    pos--;

                }

                last_was_cr = 0;

            }

            else if (codepoint == '\r') {

                last_was_cr = 1;

                continue;

            }

            else {

                graph = codepoint;

            }

            if (count == bufsize) {

                /* We filled the buffer. Attach this one to the buffers

                 * linked list, and continue with a new one. */

                MVM_string_decodestream_add_chars(tc, ds, buffer, bufsize);

                buffer = MVM_malloc(bufsize * sizeof(MVMGrapheme32));

                count = 0;

            }

            buffer[count++] = graph;

            last_accept_bytes = cur_bytes;

            last_accept_pos = pos;

            total++;

            if (stopper_chars && *stopper_chars == total) {

                reached_stopper = 1;

                goto done;

            }

            if (MVM_string_decode_stream_maybe_sep(tc, seps, codepoint)) {

                reached_stopper = 1;

                goto done;

            }

        }

        cur_bytes = cur_bytes->next;

    }

  done:

    /* Attach what we successfully parsed as a result buffer, and trim away

     * what we chewed through. */

    if (count) {

        MVM_string_decodestream_add_chars(tc, ds, buffer, count);

    }

    else {

        MVM_free(buffer);

    }

    MVM_string_decodestream_discard_to(tc, ds, last_accept_bytes, last_accept_pos);

    return reached_stopper;

}

/* Encodes the specified substring to ASCII. Anything outside of ASCII range

 * will become replaced with the supplied replacement, or an exception will be

 * thrown if there isn't one. The result string is NULL terminated, but the

 * specified size is the non-null part. */

char * MVM_string_ascii_encode_substr(MVMThreadContext *tc, MVMString *str, MVMuint64 *output_size, MVMint64 start, MVMint64 length, MVMString *replacement, MVMint32 translate_newlines) {

    /* ASCII is a single byte encoding, but \r\n is a 2-byte grapheme, so we

     * may have to resize as we go. */

    MVMuint32      startu    = (MVMuint32)start;

    MVMStringIndex strgraphs = MVM_string_graphs(tc, str);

    MVMuint32      lengthu   = (MVMuint32)(length == -1 ? strgraphs - startu : length);

    MVMuint8      *result;

    size_t         result_alloc;

    MVMuint8      *repl_bytes = NULL;

    MVMuint64      repl_length;

    /* must check start first since it's used in the length check */

    if (start < 0 || start > strgraphs)

        MVM_exception_throw_adhoc(tc, "start out of range");

    if (length < -1 || start + lengthu > strgraphs)

        MVM_exception_throw_adhoc(tc, "length out of range");

    if (replacement)

        repl_bytes = (MVMuint8 *) MVM_string_ascii_encode_substr(tc, replacement,

            &repl_length, 0, -1, NULL, translate_newlines);

    result_alloc = lengthu;

    result = MVM_malloc(result_alloc + 1);

    if (str->body.storage_type == MVM_STRING_GRAPHEME_ASCII) {

        /* No encoding needed; directly copy. */

        memcpy(result, str->body.storage.blob_ascii, lengthu);

        result[lengthu] = 0;

        if (output_size)

            *output_size = lengthu;

    }

    else {

        MVMuint32 i = 0;

        MVMCodepointIter ci;

        MVM_string_ci_init(tc, &ci, str, translate_newlines);

        while (MVM_string_ci_has_more(tc, &ci)) {

            MVMCodepoint ord = MVM_string_ci_get_codepoint(tc, &ci);

            if (i == result_alloc) {

                result_alloc += 8;

                result = MVM_realloc(result, result_alloc + 1);

            }

            if (ord >= 0 && ord <= 127) {

                result[i] = (MVMuint8)ord;

                i++;

            }

            else if (replacement) {

                if (repl_length >= result_alloc || i >= result_alloc - repl_length) {

                    result_alloc += repl_length;

                    result = MVM_realloc(result, result_alloc + 1);

                }

                memcpy(result + i, repl_bytes, repl_length);

                i += repl_length;

            }

            else {

                MVM_free(result);

                MVM_free(repl_bytes);

                MVM_exception_throw_adhoc(tc,

                    "Error encoding ASCII string: could not encode codepoint %d",

                    ord);

            }

        }

        result[i] = 0;

        if (output_size)

            *output_size = i;

    }

    MVM_free(repl_bytes);

    return (char *)result;

}

/* Encodes the specified string to ASCII.  */

char * MVM_string_ascii_encode(MVMThreadContext *tc, MVMString *str, MVMuint64 *output_size, MVMint32 translate_newlines) {

    return MVM_string_ascii_encode_substr(tc, str, output_size, 0, -1, NULL, translate_newlines);

}

/* Encodes the specified string to ASCII not returning length.  */

char * MVM_string_ascii_encode_any(MVMThreadContext *tc, MVMString *str) {

    return MVM_string_ascii_encode(tc, str, NULL, 0);

}