#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define PCRE2_CODE_UNIT_WIDTH 8
#include <pcre2.h>

int main(int argc, char const *argv[])
{
    pcre2_code *compileCode;
    PCRE2_SPTR pattern;     /* PCRE2_SPTR is a pointer to unsigned code units of */
    PCRE2_SPTR subject;
    PCRE2_SPTR replace;
    size_t subjectLength;
    size_t replaceLength;
    int subsCount;

    PCRE2_UCHAR *output = (PCRE2_UCHAR *)malloc(sizeof(PCRE2_UCHAR));
    PCRE2_SIZE outputLength;

    int errornumber;
    PCRE2_SIZE errorOffset;

    if (argc != 4) {
        printf("Usage: ./app <pattern> <replace> <subject>\n");
        return EXIT_FAILURE;
    }

    pattern = (PCRE2_SPTR)argv[1];
    replace = (PCRE2_SPTR)argv[2];
    subject = (PCRE2_SPTR)argv[3];

    subjectLength = strlen((char *)subject);
    replaceLength = strlen((char *)replace);

    compileCode = pcre2_compile(
        pattern,               /* the pattern */
        PCRE2_ZERO_TERMINATED, /* indicates pattern is zero-terminated */
        0,                     /* default options */
        &errornumber,          /* for error number */
        &errorOffset,          /* for error offset */
        NULL                   /* use default compile context */
    );

    if (compileCode == NULL) {
        PCRE2_UCHAR buffer[256];
        pcre2_get_error_message(errornumber, buffer, sizeof(buffer));
        printf("PCRE2 compilation failed at offset %d: %s\n", (int)errorOffset, buffer);
        pcre2_code_free(compileCode);
        free(output);
        return EXIT_FAILURE;
    }

    subsCount = pcre2_substitute(
        compileCode,           /*Points to the compiled pattern*/
        subject,               /*Points to the subject string*/
        PCRE2_ZERO_TERMINATED, /*subjectLength,*/ /*Length of the subject string*/
        0,                     /*Offset in the subject at which to start matching*/
        PCRE2_SUBSTITUTE_GLOBAL | PCRE2_SUBSTITUTE_OVERFLOW_LENGTH | PCRE2_SUBSTITUTE_EXTENDED,               /*Option bits*/
        NULL,                     /*Points to a match data block, or is NULL*/
        NULL,                     /*Points to a match context, or is NULL*/
        replace,               /*Points to the replacement string*/
        PCRE2_ZERO_TERMINATED, /*replaceLength,*/ /*Length of the replacement string*/
        output,               /*Points to the output buffer*/
        &outputLength          /*Points to the length of the output buffer*/
    );

    if (subsCount > 0) {
        printf("%s\ncount: %i\n", output, subsCount);
    } else if (subsCount == 0) {
        printf("No matches\n");
    } else {
        PCRE2_UCHAR buffer[256];
        pcre2_get_error_message(subsCount, buffer, sizeof(buffer));
        printf("PCRE2 substitute failed. ErrorCode %i: %s\n", (int)subsCount, buffer);
        pcre2_code_free(compileCode);
        free(output);
        return EXIT_FAILURE;
    }

    pcre2_code_free(compileCode);
    free(output);

    return EXIT_SUCCESS;
}