#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <string.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <time.h>

#include <zlib.h>

#include "GenericList.h"

#define C4GroupMaxMaker 30
#define C4GroupMaxPassword 30

typedef struct {
	char id[25];
	uint8_t Reserved1[3];
	int32_t Ver1, Ver2;
	int32_t Entries;
	char Maker[C4GroupMaxMaker + 2];
	char Password[C4GroupMaxPassword + 2];
	int32_t Creation;
	int32_t Original;
	uint8_t Reserved2[92];
} __attribute__((__packed__)) C4GroupHeader;

typedef struct {
	char FileName[257];
	uint8_t Reserved1[3];
	int32_t Packed;
	int32_t Directory;
	int32_t Size;
	int32_t Reserved2;
	int32_t Offset;
	int32_t Modified;
	uint8_t HasCRC;
	uint32_t CRC;
	uint8_t Executable;
	uint8_t Reserved3[26];
} __attribute__((__packed__)) C4GroupEntryCore;

struct list_GroupEntryList;
typedef struct {
	C4GroupEntryCore core;
	uint8_t* data;
	struct list_GroupEntryList* children;
} C4GroupEntryData;

LIST_AUTO(C4GroupEntryData, GroupEntryList)
#define ForeachGroupEntry(list) LIST_FOREACH(GroupEntryList, list, entry)

__off_t fileSizeFd(int fd)
{
	struct stat st;

	if(fstat(fd, &st) == -1)
	{
		return -1;
	}

	return st.st_size;
}

void memScrambleHeader(uint8_t* data)
{
	// XOR deface
	for(size_t i = 0; i < sizeof(C4GroupHeader); i++)
		data[i] ^= 237;
	// byte swap
	for(size_t i = 0; i + 2 < sizeof(C4GroupHeader); i += 3)
	{
		uint8_t temp = data[i];
		data[i] = data[i + 2];
		data[i + 2] = temp;
	}
}

void buildChildren(C4GroupEntryData* entry)
{
	memScrambleHeader(entry->data);
	C4GroupHeader* header = (C4GroupHeader*)entry->data;

	entry->children = GroupEntryListNew();

	uint8_t* data = entry->data + sizeof(C4GroupHeader);
	uint8_t* childData = entry->data + sizeof(C4GroupHeader) + sizeof(C4GroupEntryCore) * header->Entries;

	for(size_t i = 0; i < (size_t)header->Entries; ++i)
	{
		C4GroupEntryCore* core = (C4GroupEntryCore*)(data + sizeof(C4GroupEntryCore) * i);
		C4GroupEntryData* childEntry = &GroupEntryListAppend(entry->children, (C4GroupEntryData){.core = *core, .data = childData + core->Offset, .children = NULL})->value;

		if(core->Directory)
		{
			buildChildren(childEntry);
		}
	}
}

const char* formatTime(int32_t time)
{
	time_t tTime = time;
	static char ret[128];
	strftime(ret, sizeof(ret), "%c", localtime(&tTime));
	return ret;
}

void handleChildren(GroupEntryList* entries, size_t indent, const char* path)
{
	size_t pathLen = strlen(path);
	char* targetPath = malloc(pathLen + 260 + 1);

	strcpy(targetPath, path);
	strcpy(targetPath + pathLen++, "/");

	if(mkdir(path, 0755) == -1)
	{
		fprintf(stderr, "ERROR: Creating target directory \"%s\": %s\n", path, strerror(errno));
		goto ret;
	}

	ForeachGroupEntry(entries)
	{
		for(size_t i = 0; i < indent; ++i)
		{
			putchar('\t');
		}

		strcpy(targetPath + pathLen, entry->value.core.FileName);

// 		printf("%s\t%s\t%d B\n", targetPath, formatTime(entry->value.core.Modified), entry->value.core.Size);

		if(!entry->value.core.Directory)
		{
			int file = open(targetPath, O_WRONLY | O_CREAT, entry->value.core.Executable ? 0755 : 0644);
			if(file == -1)
			{
				fprintf(stderr, "ERROR: Creating target file \"%s\": %s\n", targetPath, strerror(errno));
				goto ret;
			}
			write(file, entry->value.data, entry->value.core.Size);

			if(close(file) == -1)
			{
				fprintf(stderr, "ERROR: Closing file \"%s\": %s\n", targetPath, strerror(errno));
			}

			struct timeval tv[2] = {{.tv_usec = 0, .tv_sec = entry->value.core.Modified}, {.tv_usec = 0, .tv_sec = entry->value.core.Modified}};
			if(utimes(targetPath, tv) == -1)
			{
				fprintf(stderr, "ERROR: Setting modification time for \"%s\": %s\n", targetPath, strerror(errno));
			}
		}

		if(entry->value.core.Directory)
		{
			handleChildren(entry->value.children, indent + 1, targetPath);
		}
	}

ret:
	free(targetPath);
}

void deleteChildren(GroupEntryList* entries)
{
	ForeachGroupEntry(entries)
	{
		if(entry->value.core.Directory)
		{
			deleteChildren(entry->value.children);
		}
	}

	GroupEntryListDestroy(entries);
}

int main(int argc, char* argv[])
{
	if(argc != 3)
	{
		fprintf(stderr, "USAGE: %s <group> <target>\n", argv[0]);
		return EXIT_FAILURE;
	}

	int file = open(argv[1], O_RDONLY);
	if(file == -1)
	{
		fprintf(stderr, "ERROR: Opening file \"%s\": %s\n", argv[1], strerror(errno));
		return EXIT_FAILURE;
	}

	__off_t size = fileSizeFd(file);
	if(size == -1)
	{
		fprintf(stderr, "ERROR: Getting file size: %s\n", strerror(errno));
		return EXIT_FAILURE;
	}
	else
	{
		printf("Size: %ld\n", size);
	}

	uint8_t* mappedFile = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, file, 0);

	if(mappedFile == MAP_FAILED)
	{
		fprintf(stderr, "ERROR: Mapping file: %s\n", strerror(errno));
		return EXIT_FAILURE;
	}

	if(close(file) == -1)
	{
		fprintf(stderr, "ERROR: Closing file: %s\n", strerror(errno));
		return EXIT_FAILURE;
	}

	if((mappedFile[0] != 0x1e && mappedFile[0] != 0x1f) || (mappedFile[1] != 0x8c && mappedFile[1] != 0x8b))
	{
		fprintf(stderr, "ERROR: The file is not a valid group file. Magic bytes don't match.\n");
		return EXIT_FAILURE;
	}

	mappedFile[0] = 0x1f;
	mappedFile[1] = 0x8b;

	z_stream strm = {
		.zalloc = NULL,
		.zfree = NULL,
		.opaque = NULL,
		.next_in = mappedFile,
		.avail_in = size
	};

	int ret = inflateInit2(&strm, 15 + 16); // window size 15 + automatic gzip

	if(ret != Z_OK)
	{
		fprintf(stderr, "ERROR: inflateInit2: %s\n", zError(ret));
		return EXIT_FAILURE;
	}

	C4GroupHeader header;

	strm.next_out = (Bytef*)&header;
	strm.avail_out = sizeof(header);

	ret = inflate(&strm, Z_SYNC_FLUSH);
	if(ret != Z_OK)
	{
		fprintf(stderr, "ERROR: inflating header: %s\n", zError(ret));
		return EXIT_FAILURE;
	}

	memScrambleHeader((uint8_t*)&header);

	printf("Version %d.%d\n", header.Ver1, header.Ver2);
	printf("%d Entries\n", header.Entries);
	printf("%sOriginal\n", header.Original == 1234567 ? "" : "Not ");
	printf("Created %s\n", formatTime(header.Creation));
	puts(header.id);
	puts(header.Maker);

	GroupEntryList* entries = GroupEntryListNew();

	for(size_t i = 0; i < (size_t)header.Entries; ++i)
	{
		GroupEntryListEntry* listEntry = GroupEntryListAppend(entries, (C4GroupEntryData){.data = NULL, .children = NULL});
		strm.next_out = (Bytef*)&listEntry->value.core;
		strm.avail_out = sizeof(listEntry->value.core);

		ret = inflate(&strm, Z_SYNC_FLUSH);
		if(ret != Z_OK)
		{
			fprintf(stderr, "ERROR: inflating header: %s\n", zError(ret));
			return EXIT_FAILURE;
		}
	}

	GroupEntryListEntry* last = GroupEntryListLast(entries);
	size_t uncompressedSize = last->value.core.Offset + last->value.core.Size;

	uint8_t* data = malloc(uncompressedSize);

	strm.next_out = data;
	strm.avail_out = uncompressedSize;

	ret = inflate(&strm, Z_SYNC_FLUSH);
	if(ret != Z_STREAM_END)
	{
		fprintf(stderr, "ERROR: inflating header: %s\n", zError(ret));
		return EXIT_FAILURE;
	}

	inflateEnd(&strm);

	if(munmap(mappedFile, size) == -1)
	{
		fprintf(stderr, "ERROR: Unmapping file: %s\n", strerror(errno));
		return EXIT_FAILURE;
	}

	ForeachGroupEntry(entries)
	{
		entry->value.data = data + entry->value.core.Offset;

		if(entry->value.core.Directory)
		{
			buildChildren(&entry->value);
		}
	}

	handleChildren(entries, 0, argv[2]);

	deleteChildren(entries);

	free(data);

	return EXIT_SUCCESS;
}