/* binary_scan - demonstrates BINARY mode: matching against raw bytes with
 * no decoding step at all, where every value 0-255 is an ordinary input
 * character, including 0x00 (NUL) and 0x0A (the byte '\n' means in text).
 * This is the one thing ASCII and UTF8 mode structurally cannot do: ASCII
 * mode still treats the subject as bytes but restricts \d/\w/\s to the
 * ASCII subset, and UTF8 mode decodes the subject before matching at all,
 * so an arbitrary byte class spanning 0x00-0xFF describes decoded code
 * points there, not raw bytes on the wire.
 *
 * The scenario: a small binary record format concatenated in one buffer,
 * each record a 2-byte magic number followed by 4 raw payload bytes that
 * may be anything, including bytes a C string function would treat as a
 * terminator or a line break. A pattern built from re.escape'd magic bytes
 * and a [\x00-\xff]{4} class extracts every record correctly regardless.
 */
#include "regexx.h"
#include <stdio.h>
#include <string.h>

typedef struct { int n; } Ctx;

static void print_record(void *ctx, const Match *m_const) {
    Ctx *c = ctx;
    Match *m = (Match *)m_const;
    const char *g; size_t glen;
    Match_group(m, NULL, 0, &g, &glen);
    printf("record %d: magic=%02x%02x payload=", c->n, (unsigned char)g[0], (unsigned char)g[1]);
    for (size_t i = 2; i < glen; i++) printf("%02x ", (unsigned char)g[i]);
    printf("\n");
    c->n++;
}

int main(void) {
    /* Three records, back to back, with no separator: a real length-value
     * binary format would carry its own framing; this example only needs
     * a fixed-size payload to keep the pattern simple. Payload bytes
     * deliberately include 0x00 and 0x0a, the two values that would break
     * a NUL-terminated-string or line-oriented approach to scanning this
     * same buffer. */
    uint8_t data[] = {
        0xca, 0xfe, 0x01, 0x00, 0x00, 0x00,   /* record 0: payload has an embedded NUL */
        0xca, 0xfe, 0x0a, 0x0a, 0xff, 0x7f,   /* record 1: payload has embedded 0x0a bytes */
        0xca, 0xfe, 0xde, 0xad, 0xbe, 0xef,   /* record 2: ordinary payload */
    };

    const char *pattern = "\\xca\\xfe[\\x00-\\xff]{4}";
    PatternError err; memset(&err, 0, sizeof err);
    Pattern *pat = re_compile(pattern, strlen(pattern), BINARY, &err);
    if (!pat) {
        fprintf(stderr, "compile error: %s\n", err.msg);
        PatternError_free(&err);
        return 1;
    }

    Input *in = Input_from_buffer(data, sizeof data);
    Ctx ctx = { 0 };
    int n = Pattern_finditer(pat, in, 0, -1, print_record, &ctx);
    printf("total records found: %d (buffer is %zu bytes with %d embedded NUL, %d embedded 0x0a)\n",
           n, sizeof data, 1, 2);

    Input_free(in);
    Pattern_free(pat);
    return 0;
}