/**
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0.
 */

#include <aws/common/byte_buf.h>
#include <aws/common/file.h>
#include <aws/common/linked_list.h>
#include <aws/common/logging.h>
#include <aws/common/string.h>

#include <errno.h>

FILE *aws_fopen(const char *file_path, const char *mode) {
    if (!file_path || strlen(file_path) == 0) {
        AWS_LOGF_ERROR(AWS_LS_COMMON_IO, "static: Failed to open file. path is empty");
        aws_raise_error(AWS_ERROR_FILE_INVALID_PATH);
        return NULL;
    }

    if (!mode || strlen(mode) == 0) {
        AWS_LOGF_ERROR(AWS_LS_COMMON_IO, "static: Failed to open file. mode is empty");
        aws_raise_error(AWS_ERROR_INVALID_ARGUMENT);
        return NULL;
    }

    struct aws_string *file_path_str = aws_string_new_from_c_str(aws_default_allocator(), file_path);
    struct aws_string *mode_str = aws_string_new_from_c_str(aws_default_allocator(), mode);

    FILE *file = aws_fopen_safe(file_path_str, mode_str);
    aws_string_destroy(mode_str);
    aws_string_destroy(file_path_str);

    return file;
}

int aws_byte_buf_init_from_file(struct aws_byte_buf *out_buf, struct aws_allocator *alloc, const char *filename) {

    AWS_ZERO_STRUCT(*out_buf);
    FILE *fp = aws_fopen(filename, "rb");

    if (fp) {
        if (fseek(fp, 0L, SEEK_END)) {
            int errno_value = errno; /* Always cache errno before potential side-effect */
            AWS_LOGF_ERROR(AWS_LS_COMMON_IO, "static: Failed to seek file %s with errno %d", filename, errno_value);
            fclose(fp);
            return aws_translate_and_raise_io_error(errno_value);
        }

        size_t allocation_size = (size_t)ftell(fp) + 1;
        /* Tell the user that we allocate here and if success they're responsible for the free. */
        if (aws_byte_buf_init(out_buf, alloc, allocation_size)) {
            fclose(fp);
            return AWS_OP_ERR;
        }

        /* Ensure compatibility with null-terminated APIs, but don't consider
         * the null terminator part of the length of the payload */
        out_buf->len = out_buf->capacity - 1;
        out_buf->buffer[out_buf->len] = 0;

        if (fseek(fp, 0L, SEEK_SET)) {
            int errno_value = errno; /* Always cache errno before potential side-effect */
            AWS_LOGF_ERROR(AWS_LS_COMMON_IO, "static: Failed to seek file %s with errno %d", filename, errno_value);
            aws_byte_buf_clean_up(out_buf);
            fclose(fp);
            return aws_translate_and_raise_io_error(errno_value);
        }

        size_t read = fread(out_buf->buffer, 1, out_buf->len, fp);
        int errno_cpy = errno; /* Always cache errno before potential side-effect */
        fclose(fp);
        if (read < out_buf->len) {
            AWS_LOGF_ERROR(AWS_LS_COMMON_IO, "static: Failed to read file %s with errno %d", filename, errno_cpy);
            aws_secure_zero(out_buf->buffer, out_buf->len);
            aws_byte_buf_clean_up(out_buf);
            return aws_raise_error(AWS_ERROR_SYS_CALL_FAILURE);
        }

        return AWS_OP_SUCCESS;
    }

    return AWS_OP_ERR;
}

bool aws_is_any_directory_separator(char value) {
    return value == '\\' || value == '/';
}

struct aws_directory_iterator {
    struct aws_linked_list list_data;
    struct aws_allocator *allocator;
    struct aws_linked_list_node *current_node;
};

struct directory_entry_value {
    struct aws_directory_entry entry;
    struct aws_byte_buf path;
    struct aws_byte_buf relative_path;
    struct aws_linked_list_node node;
};

static bool s_directory_iterator_directory_entry(const struct aws_directory_entry *entry, void *user_data) {
    struct aws_directory_iterator *iterator = user_data;
    struct directory_entry_value *value = aws_mem_calloc(iterator->allocator, 1, sizeof(struct directory_entry_value));

    value->entry = *entry;
    aws_byte_buf_init_copy_from_cursor(&value->path, iterator->allocator, entry->path);
    value->entry.path = aws_byte_cursor_from_buf(&value->path);
    aws_byte_buf_init_copy_from_cursor(&value->relative_path, iterator->allocator, entry->relative_path);
    value->entry.relative_path = aws_byte_cursor_from_buf(&value->relative_path);
    aws_linked_list_push_back(&iterator->list_data, &value->node);

    return true;
}

struct aws_directory_iterator *aws_directory_entry_iterator_new(
    struct aws_allocator *allocator,
    const struct aws_string *path) {
    struct aws_directory_iterator *iterator = aws_mem_acquire(allocator, sizeof(struct aws_directory_iterator));
    iterator->allocator = allocator;
    aws_linked_list_init(&iterator->list_data);

    /* the whole point of this iterator is to avoid recursion, so let's do that by passing recurse as false. */
    if (AWS_OP_SUCCESS ==
        aws_directory_traverse(allocator, path, false, s_directory_iterator_directory_entry, iterator)) {
        if (!aws_linked_list_empty(&iterator->list_data)) {
            iterator->current_node = aws_linked_list_front(&iterator->list_data);
        }
        return iterator;
    }

    aws_mem_release(allocator, iterator);
    return NULL;
}

int aws_directory_entry_iterator_next(struct aws_directory_iterator *iterator) {
    struct aws_linked_list_node *node = iterator->current_node;

    if (!node || node->next == aws_linked_list_end(&iterator->list_data)) {
        return aws_raise_error(AWS_ERROR_LIST_EMPTY);
    }

    iterator->current_node = aws_linked_list_next(node);

    return AWS_OP_SUCCESS;
}

int aws_directory_entry_iterator_previous(struct aws_directory_iterator *iterator) {
    struct aws_linked_list_node *node = iterator->current_node;

    if (!node || node == aws_linked_list_begin(&iterator->list_data)) {
        return aws_raise_error(AWS_ERROR_LIST_EMPTY);
    }

    iterator->current_node = aws_linked_list_prev(node);

    return AWS_OP_SUCCESS;
}

void aws_directory_entry_iterator_destroy(struct aws_directory_iterator *iterator) {
    while (!aws_linked_list_empty(&iterator->list_data)) {
        struct aws_linked_list_node *node = aws_linked_list_pop_front(&iterator->list_data);
        struct directory_entry_value *value = AWS_CONTAINER_OF(node, struct directory_entry_value, node);

        aws_byte_buf_clean_up(&value->path);
        aws_byte_buf_clean_up(&value->relative_path);

        aws_mem_release(iterator->allocator, value);
    }

    aws_mem_release(iterator->allocator, iterator);
}

const struct aws_directory_entry *aws_directory_entry_iterator_get_value(
    const struct aws_directory_iterator *iterator) {
    struct aws_linked_list_node *node = iterator->current_node;

    if (!iterator->current_node) {
        return NULL;
    }

    struct directory_entry_value *value = AWS_CONTAINER_OF(node, struct directory_entry_value, node);
    return &value->entry;
}