#include <sections.h>
#include <wasm_types.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>

static int check_value_type(FILE *const f)
{
    varint7 value_type;

    if (varint7_read(f, &value_type))
    {
        fprintf(stderr, "%s: varint7_read failed\n", __func__);
        return -1;
    }

    return 0;
}

static int check_func_type(FILE *const f)
{
    varint7 form;
    varuint32 param_count;

    if (varint7_read(f, &form))
    {
        fprintf(stderr, "%s: varint7_read failed\n", __func__);
        return -1;
    }
    else if (varuint32_read(f, &param_count))
    {
        fprintf(stderr, "%s: varuint32_read failed\n", __func__);
        return -1;
    }

    for (varuint32 i = 0; i < param_count; i++)
        if (check_value_type(f))
        {
            fprintf(stderr, "%s: check_value_type failed\n", __func__);
            return -1;
        }

    varuint1 return_count;

    if (varuint1_read(f, &return_count))
    {
        fprintf(stderr, "%s: varuint1_read failed\n", __func__);
        return -1;
    }
    else if (return_count && check_value_type(f))
    {
        fprintf(stderr, "%s: check_value_type 2 failed\n", __func__);
        return -1;
    }

    return 0;
}

static int check(FILE *const f, const unsigned long len)
{
    const long start = ftell(f);
    varuint32 count;

    if (start < 0)
    {
        fprintf(stderr, "%s: ftell(3): %s\n", __func__, strerror(errno));
        return -1;
    }
    else if (varuint32_read(f, &count))
    {
        fprintf(stderr, "%s: varuint32_read failed\n", __func__);
        return -1;
    }

    for (varuint32 i = 0; i < count; i++)
        if (check_func_type(f))
        {
            fprintf(stderr, "%s: check_func_type failed\n", __func__);
            return -1;
        }

    const long end = ftell(f);

    if (end < 0)
    {
        fprintf(stderr, "%s: ftell(3): %s\n", __func__, strerror(errno));
        return -1;
    }

    const unsigned long size = end - start;

    if (size != len)
    {
        fprintf(stderr, "%s: size exceeded (%lu expected, got %lu)\n",
                __func__, len, size);
        return -1;
    }

    return 0;
}

int section_type(struct wasmfs *const w, FILE *const f,
    const unsigned long len)
{
    if (w->sections.type)
    {
        fprintf(stderr, "%s: ignoring duplicate section\n", __func__);
        return 0;
    }

    const long offset = ftell(f);

    if (offset < 0)
    {
        fprintf(stderr, "%s: ftell(3): %s\n", __func__, strerror(errno));
        return -1;
    }
    else if (check(f, len))
    {
        fprintf(stderr, "%s: check failed\n", __func__);
        return -1;
    }

    w->sections.type = offset;
    return 0;
}