#include "format_ops.h"

#include <stdlib.h>

#include <string.h>

char *format_string(const char *fmt, const LatValue *args, size_t argc, char **err) {

    size_t buf_cap = 128;

    size_t buf_len = 0;

    char *buf = malloc(buf_cap);

    if (!buf) { *err = strdup("format: out of memory"); return NULL; }

    size_t arg_idx = 0;

    const char *p = fmt;

    while (*p) {

        /* Escaped braces: {{ -> {, }} -> } */

        if (p[0] == '{' && p[1] == '{') {

            if (buf_len + 1 >= buf_cap) { buf_cap *= 2; buf = realloc(buf, buf_cap); }

            buf[buf_len++] = '{';

            p += 2;

            continue;

        }

        if (p[0] == '}' && p[1] == '}') {

            if (buf_len + 1 >= buf_cap) { buf_cap *= 2; buf = realloc(buf, buf_cap); }

            buf[buf_len++] = '}';

            p += 2;

            continue;

        }

        /* Placeholder: {} */

        if (p[0] == '{' && p[1] == '}') {

            if (arg_idx >= argc) {

                free(buf);

                *err = strdup("format: not enough arguments for placeholders");

                return NULL;

            }

            char *display = value_display(&args[arg_idx]);

            size_t dlen = strlen(display);

            while (buf_len + dlen >= buf_cap) { buf_cap *= 2; buf = realloc(buf, buf_cap); }

            memcpy(buf + buf_len, display, dlen);

            buf_len += dlen;

            free(display);

            arg_idx++;

            p += 2;

            continue;

        }

        /* Regular character */

        if (buf_len + 1 >= buf_cap) { buf_cap *= 2; buf = realloc(buf, buf_cap); }

        buf[buf_len++] = *p;

        p++;

    }

    buf[buf_len] = '\0';

    *err = NULL;

    return buf;

}