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

#include "apfl.h"

#include "alloc.h"

struct string_source_reader {
    struct apfl_allocator allocator;
    struct apfl_string_view sv;
    size_t off;
};

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

    struct string_source_reader *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;
}

void *
apfl_string_source_reader_new(struct apfl_allocator allocator, struct apfl_string_view sv)
{
    struct string_source_reader *ctx = ALLOC_OBJ(allocator, struct string_source_reader);
    if (ctx == NULL) {
        return NULL;
    }

    ctx->allocator = allocator;
    ctx->sv = sv;
    ctx->off = 0;

    return ctx;
}

void
apfl_string_source_reader_destroy(void *opaque)
{
    struct string_source_reader *ctx = opaque;
    if (ctx == NULL) {
        return;
    }

    FREE_OBJ(ctx->allocator, ctx);
}