#include <assert.h>
#include <string.h>

#include "apfl.h"

static bool
reader_callback(void *opaque, char *buf, size_t *len, bool need)
{
    (void)need;

    struct apfl_string_source_reader_data *ctx = opaque;

    size_t maxlen = *len;
    size_t remain_len = ctx->sv.len - ctx->off;
    *len = maxlen < remain_len ? maxlen : remain_len;
    memcpy(buf, ctx->sv.bytes + ctx->off, *len);
    ctx->off += *len;
    assert(ctx->off <= ctx->sv.len);

    return true;
}

struct apfl_string_source_reader_data
apfl_string_source_reader_create(struct apfl_string_view sv)
{
    return (struct apfl_string_source_reader_data) {
        .sv = sv,
        .off = 0,
    };
}

struct apfl_source_reader apfl_string_source_reader(struct apfl_string_source_reader_data *data)
{
    return (struct apfl_source_reader) {
        .callback = reader_callback,
        .opaque = data,
    };
}