#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "stuffy.h"

// Put a module header into a HeaderStruct and read (skip) module data
// Returns size of data read when reading a module header
int ReadSingleModuleFromArchive(int fd, ModuleStruct* module)
{
    int readSize;
    long long int moduleSize;
    readSize = read(fd, &(module->moduleHeader), sizeof(module->moduleHeader));
    moduleSize = (long long) module->moduleHeader.moduleInfo.st_size;
    module->moduleData = malloc(moduleSize);
    readSize = read(fd, module->moduleData, moduleSize);
    return readSize;
}

// Write a single module into file
int WriteSingleModuleToArchive(int fd, ModuleStruct* module)
{
    int writeSize;
    long long int moduleSize;
    moduleSize = (long long) module->moduleHeader.moduleInfo.st_size;
    writeSize = write(fd, &(module->moduleHeader), sizeof(module->moduleHeader));
    writeSize = write(fd, module->moduleData, moduleSize);
    return writeSize;
}

void PrintModuleHeader(ModuleStruct* module)
{
    printf("Name: %s | ", module->moduleHeader.moduleName);
    printf("Size: %ld\n", module->moduleHeader.moduleInfo.st_size);
    return;
}

int OpenArchive(char* archiveName, int flags)
{
    int archiveFD = open(archiveName, flags, 0644);
    if (archiveFD < 0)
    {
        perror("Archive");
        return -1;
    }
    return archiveFD;
    
}

void LoadModuleFromFile(char* filename, ModuleStruct* module)
{
    stat(filename, &(module->moduleHeader.moduleInfo));
    long long int moduleSize;
    moduleSize = (long long) module->moduleHeader.moduleInfo.st_size;
    module->moduleData = malloc(moduleSize);
    int fdInput = open(filename, O_RDONLY);
    read(fdInput, module->moduleData, moduleSize);
    close(fdInput);
    return;
}

// Checks if operation went ok, if not then prints message and exits
void SafetyCheck(int status, char* message)
{
    if (status)
    {
        fprintf(stderr, "%s\n", message);
        exit(1);
    }
    return;
}

// Strip path from filename for adding to archive
char* StripFilename(char* filename)
{
    int nameStartPosition = -1;
    for (int i = 0; i < strlen(filename); i++)
        if (filename[i] == '/')
            nameStartPosition = i+1;
    if (nameStartPosition == -1)
        nameStartPosition = 0;
    int copySize = strlen(filename) - nameStartPosition;
    char* newFilename = malloc(copySize + 1);
    strncpy(newFilename, &filename[nameStartPosition], copySize);
    strcat(newFilename, "\0");
    return newFilename;
}

// Overhead function for archive operations
void Stuffy(int argc, char* argv[])
{
    int archiveAction = StuffyArgument(argc, argv);
    if (archiveAction < 0)
    {
        fprintf(stderr, "Usage: stuffy.out [OPTION] [ARCHIVE] [FILE]");
        exit(1);
    }
    StuffyAction(argc, argv, archiveAction);
    return;
}

// Checks for argument, if argument is found then returns argument number.
// Returns -1 if not found
int StuffyArgument(int argc, char* argv[])
{
    for (int i = 1; i < argc; i++)
    {
        if ((argv[i][0] == '-') && (argv[i][1] == 'a'))
            return 0;
        if ((argv[i][0] == '-') && (argv[i][1] == 'r'))
            return 1;
        if ((argv[i][0] == '-') && (argv[i][1] == 'l'))
            return 2;
        if ((argv[i][0] == '-') && (argv[i][1] == 'e'))
            return 3;
    }
    return -1;
}

// Redirects program to necessary action function
void StuffyAction(int argc, char* argv[], int archiveAction)
{
    if (archiveAction == 0)
        AddToArchive(argv[2], argv[3]);
    if (archiveAction == 1)
        RemoveFromArchive(argv[2], argv[3]);
    if (archiveAction == 2)
        ListArchive(argv[2]);
    if (archiveAction == 3)
        ExtractArchive(argc, argv);
    return;
}

// Checks if filename is found in a header of archive
int IsFileArchived(char* archiveName, char* filename)
{
    ModuleStruct module;
    ssize_t readSize;
    char* newFilename = StripFilename(filename);
    int archiveFD = OpenArchive(archiveName, O_RDONLY | O_CREAT);
    do
    {
        readSize = ReadSingleModuleFromArchive(archiveFD, &(module));
        free(module.moduleData);
        if (strcmp(module.moduleHeader.moduleName, newFilename) == 0)
        {
            free(newFilename);
            close(archiveFD);
            return 1;
        }
    } while (readSize > 0);
    free(newFilename);
    close(archiveFD);
    return 0;
}

// Check through archive for file, if in archive then inform user
// Adds file to archive and can be repeatedly used to add more to the archive
// If file is already in archive, then exit, let user know, and suggest removing
//      file already inside the archive
void AddToArchive(char* archiveName, char* filename)
{
    ModuleStruct module;
    ssize_t readSize;
    char* filenameCleaned = StripFilename(filename);
    if (IsFileArchived(archiveName, filenameCleaned))
    {
        fprintf(stderr, "File already exists in archive, try removing file first.\n");
        return;
    }
    if (access(filename, F_OK))
    {
        fprintf(stderr, "%s not found.\n", filename);
        return;
    }
    int archiveFD = OpenArchive(archiveName, O_WRONLY | O_APPEND| O_CREAT);
    LoadModuleFromFile(filename, &module);
    strcpy(module.moduleHeader.moduleName, filenameCleaned);
    WriteSingleModuleToArchive(archiveFD, &module);
    free(filenameCleaned);
    free(module.moduleData);
    close(archiveFD);
    return;
}

// Check through archive for file, if file exists with name, remove it
// If file not in archive, print "somefile was not found."
void RemoveFromArchive(char* archiveName, char* filename)
{
    ssize_t readSize;
    char* filenameCleaned = StripFilename(filename);
    char tempArchiveName[strlen(archiveName)+5];
    strcpy(tempArchiveName, archiveName);
    strcat(tempArchiveName, ".tmp\0");
    int archiveFile = open(archiveName, O_RDWR | O_CREAT, 0644);
    SafetyCheck((archiveFile < 0), "Archive failed to open.");
    if (!IsFileArchived(archiveName, filenameCleaned))
    {
        fprintf(stderr, "Failed to find %s\n", filenameCleaned);
        return;
    } 
    ModuleStruct module;
    int newArchiveFD = OpenArchive(tempArchiveName, O_WRONLY | O_CREAT);
    readSize = ReadSingleModuleFromArchive(archiveFile, &(module));
    while (readSize > 0)
    {
        if (strcmp(module.moduleHeader.moduleName, filenameCleaned) != 0)
            WriteSingleModuleToArchive(newArchiveFD, &module);
        free(module.moduleData);
        readSize = ReadSingleModuleFromArchive(archiveFile, &(module));
    }
    close(archiveFile);
    close(newArchiveFD);
    SafetyCheck(remove(archiveName), "Old archive failed removal.");
    SafetyCheck(rename(tempArchiveName, archiveName), 
                "New archive failed name change.");
    free(filenameCleaned);
    return;
}

// List names and sizes of files stored in archive
// Last line prints total size of all files in archive
void ListArchive(char* archiveName)
{
    int archiveFile = open(archiveName, O_RDONLY);
    ssize_t readSize;
    SafetyCheck((archiveFile < 0), "Archive failed to open.");
    ModuleStruct module;
    do
    {
        readSize = ReadSingleModuleFromArchive(archiveFile, &module);
        if (readSize > 0)
        {
            PrintModuleHeader(&module);
            free(module.moduleData);
        }
    } while (readSize > 0);
    return;
}

int Test_ListArchive(char* archiveName)
{
    struct stat statArchive;
    int archiveFD = OpenArchive(archiveName, O_RDONLY);
    ssize_t readSize;
    long int sizeTotal = 0;
    if (archiveFD < 0)
        return -1;
    ModuleStruct module;
    stat(archiveName, &statArchive);
    do
    {
        readSize = ReadSingleModuleFromArchive(archiveFD, &module);
        if (readSize > 0)
        {
            sizeTotal += sizeof(module.moduleHeader);
            sizeTotal += module.moduleHeader.moduleInfo.st_size;
        }
        free(module.moduleData);
    } while (readSize > 0);
    return sizeTotal;
}

// Extract data of name file from archive to stdout, which is then redirected
// Extracted data remains in archive
int _ExtractArchive(char* archiveName, char* filenameIn)
{
    ssize_t readSize;
    ssize_t writeSize = 0;
    long long int moduleSize;
    char* filenameCleaned = StripFilename(filenameIn);
    int archiveFile = open(archiveName, O_RDWR | O_CREAT, 0644);
    if (!IsFileArchived(archiveName, filenameCleaned))
    {
        fprintf(stderr, "Failed to find %s\n", filenameCleaned);
        return -1;
    } 
    ModuleStruct module;
    readSize = ReadSingleModuleFromArchive(archiveFile, &(module));
    while (readSize > 0)
    {
        if (strcmp(module.moduleHeader.moduleName, filenameCleaned) == 0)
            writeSize += write(STDOUT_FILENO, module.moduleData, module.moduleHeader.moduleInfo.st_size);
        free(module.moduleData);
        readSize = ReadSingleModuleFromArchive(archiveFile, &(module));
    }
    close(archiveFile);
    free(filenameCleaned);
    return writeSize;
}

void ExtractArchive(int argc, char* argv[])
{
    int writeSize;
    writeSize = _ExtractArchive(argv[2], argv[3]);
    return;
}