/* This file is part of Nekopack.

   Copyright (C) 2017 Jakob Tsar-Fox, All Rights Reserved.

   Nekopack is free software: you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the
   Free Software Foundation, either version 3 of the License, or (at
   your option) any later version.

   Nekopack is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with Nekopack. If not, see <http://www.gnu.org/licenses/>. */

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include <iconv.h>
#include <zlib.h>

#include "cli.h"
#include "defs.h"
#include "extract.h"
#include "file.h"
#include "write.h"

#define ELIF_MAGIC 0x46696c65
#define FILE_MAGIC 0x656c6946
#define HNFN_MAGIC 0x6e666e68
#define NEKO_MAGIC 0x6f6b656e

elif_node *read_elif_entry(memory_stream *data_stream);
void read_stream(void *destination, Bytef **source, size_t size);


/* Decompresses, decrypts, and writes files in the XP3 archive to disk
   according to entries in the table. Will return prematurely if there
   isn't enough memory to store the linked lists. */
void extract(memory_stream data_stream, FILE *archive) {
    /* eliF and File entries are stored in a linked list as they're
       seen because the order of entries in XP3 archives is not
       guaranteed to be chronological. calloc is used to prevent the
       "next" pointer from being garbage and causing a segfault. */
    elif_node *elif_new, *elif_root = calloc(sizeof(elif_node), 1);
    file_node *file_new, *file_root = calloc(sizeof(file_node), 1);

    int stream_ended = 0;
    uint32_t entry_magic;
    uint64_t entry_size;
    do {
        read_stream(&entry_magic, &data_stream.data, sizeof(uint32_t));
        read_stream(&entry_size, &data_stream.data, sizeof(uint64_t));

        switch (entry_magic) {
            /* hnfn, neko, and eliF entries are all identical.

               The size given by the entry header doesn't match the
               actual entry size, so it isn't passed to the function. */
            case ELIF_MAGIC:
            case HNFN_MAGIC:
            case NEKO_MAGIC:
                elif_new = read_elif_entry(&data_stream);
                if (elif_new == NULL) {
                    fprintf(stderr, "Insufficient memory.\n");
                    free_elif_nodes(elif_root);
                    free_file_nodes(file_root);
                    return;
                }
                defer_elif_node(elif_new, elif_root);
                break;
            case FILE_MAGIC:
                file_new = read_file_entry(&data_stream,
                                           data_stream.data + entry_size);
                if (file_new == NULL) {
                    fprintf(stderr, "Insufficient memory.\n");
                    free_elif_nodes(elif_root);
                    free_file_nodes(file_root);
                    return;
                }
                defer_file_node(file_new, file_root);
                break;
            default:
                stream_ended = 1;
        }
    } while (!stream_ended);

    write_files(file_root, elif_root, archive);
    free_elif_nodes(elif_root);
    free_file_nodes(file_root);
}


/* Writes the associated filename for each eliF entry in the table. */
void list(memory_stream data_stream) {
    int stream_ended = 0;
    uint32_t entry_magic;
    uint64_t entry_size;
    elif_node *temporary;
    do {
        read_stream(&entry_magic, &data_stream.data, sizeof(uint32_t));
        read_stream(&entry_size, &data_stream.data, sizeof(uint64_t));

        switch (entry_magic) {
            case ELIF_MAGIC:
            case HNFN_MAGIC:
            case NEKO_MAGIC:
                temporary = read_elif_entry(&data_stream);
                printf("%s\n", temporary->file_name);
                free(temporary->file_name);
                free(temporary);
                break;
            case FILE_MAGIC:
                data_stream.data += entry_size;
                break;
            default:
                stream_ended = 1;
        }
    } while (!stream_ended);
}


/* Wrapper for memcpy which increments the source operand
   by the amount of bytes read to simulate a file stream. */
void read_stream(void *destination, Bytef **source, size_t size) {
    memcpy(destination, *source, size);
    *source += size;
}


/* Creates a node for an eliF entry, which can be deferred in a linked
   list. NULL will be returned if there isn't enough memory to contain
   the node structure or the filenames. */
elif_node *read_elif_entry(memory_stream *data_stream) {
    uint32_t file_key;
    uint16_t name_size;
    read_stream(&file_key, &data_stream->data, sizeof(uint32_t));
    read_stream(&name_size, &data_stream->data, sizeof(uint16_t));

    char *file_name;
    if (name_size < 0x100) {
        /* The filenames are terminated by null bytes,
           but that isn't counted in the name size. */
        char *input_buffer = malloc(name_size * 2 + 2);
        read_stream(input_buffer, &data_stream->data, name_size * 2 + 2);
        if (input_buffer == NULL)
            return NULL;

        /* name_size + 1 is unreliable since we're going back to UTF-8
           and some characters (especially Japanese ones) can be wide.
           To compensate we just allocate a buffer that could fit the
           UTF-16LE data and utilize null-bytes to terminate names. */
        file_name = malloc(name_size * 2 + 2);
        if (file_name == NULL) {
            free(input_buffer);
            return NULL;
        }

        /* iconv is the less-portable glibc way of doing it. It seems to
           be in the OpenBSD manpages, though, so I'm not worried. */
        size_t in_size = name_size * 2 + 2, out_size = name_size * 2 + 2;
        char *in_start = input_buffer, *out_start = file_name;
        iconv_t conversion = iconv_open("UTF-8", "UTF-16LE");
        iconv(conversion, &in_start, &in_size, &out_start, &out_size);
        iconv_close(conversion);

        free(input_buffer);
    } else {
        /* It's safe to assume that a filename that
           large is the flashy copyright notice. */
        data_stream->data += name_size * 2 + 2;
        file_name = strdup("COPYING.txt");
    }

    elif_node *parsed = malloc(sizeof(elif_node));
    if (parsed == NULL) {
        free(file_name);
        return NULL;
    }
    parsed->key = file_key;
    parsed->file_name = file_name;
    parsed->next = NULL;
    return parsed;
}