#include "fun.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void printElf(const char *fileName)
{
    FILE *fp = fopen(fileName, "rb");
    if (fp == NULL)
    {
        printf("Error: cannot open file\n");
        return;
    }

    Elf32_Ehdr ehdr;

    fread(&ehdr, sizeof(Elf32_Ehdr), 1, fp);

    fclose(fp);

    printf("ELF header:\n");

    printf("  Magic number:\t\t\t\t\t\t%02x %02x %02x %02x\n", ehdr.e_ident[0], ehdr.e_ident[1], ehdr.e_ident[2], ehdr.e_ident[3]);

    printf("  Class:\t\t\t\t\t\t");
    switch (ehdr.e_ident[EI_CLASS])
    {
    case ELFCLASSNONE:
        printf("Invalid class\n");
        break;
    case ELFCLASS32:
        printf("ELF32\n");
        break;
    case ELFCLASS64:
        printf("ELF64\n");
        break;
    default:
        printf("Unknown class (0x%x)\n", ehdr.e_ident[4]);
        break;
    }

    printf("  Data:\t\t\t\t\t\t\t");
    switch (ehdr.e_ident[EI_DATA])
    {
    case ELFDATANONE:
        printf("Invalid data encoding\n");
        break;
    case ELFDATA2LSB:
        printf("2's complement, little endian\n");
        break;
    case ELFDATA2MSB:
        printf("2's complement, big endian\n");
        break;
    default:
        printf("Unknown data encoding (0x%x)\n", ehdr.e_ident[5]);
        break;
    }

    printf("  Version:\t\t\t\t\t\t");
    switch (ehdr.e_ident[EI_VERSION])
    {
    case EV_NONE:
        printf("Invalid version\n");
        break;
    case EV_CURRENT:
        printf("Current version\n");
        break;
    default:
        printf("Unknown version (0x%x)\n", ehdr.e_ident[6]);
        break;
    }

    printf("  OS/ABI:\t\t\t\t\t\t");
    switch (ehdr.e_ident[EI_OSABI])
    {
    case ELFOSABI_NONE:
        printf("UNIX System V ABI\n");
        break;
    default:
        printf("Unknown OS/ABI (0x%x)\n", ehdr.e_ident[7]);
        break;
    }

    printf("  ABI Version:\t\t\t\t\t\t%d\n", ehdr.e_ident[EI_ABIVERSION]);

    printf("  Type:\t\t\t\t\t\t\t");
    switch (ehdr.e_type)
    {
    case ET_NONE:
        printf("No file type\n");
        break;
    case ET_REL:
        printf("Relocatable file\n");
        break;
    case ET_EXEC:
        printf("Executable file\n");
        break;
    case ET_DYN:
        printf("Shared object file\n");
        break;
    case ET_CORE:
        printf("Core file\n");
        break;
    case ET_LOPROC:
        printf("Processor-specific\n");
        break;
    case ET_HIPROC:
        printf("Processor-specific\n");
        break;
    default:
        printf("Unknown type (0x%x)\n", ehdr.e_type);
        break;
    }

    printf("  Machine:\t\t\t\t\t\t");
    switch (ehdr.e_machine)
    {
    case EM_386:
        printf("Intel 80386\n");
        break;
    default:
        printf("Unknown type (0x%x)\n", ehdr.e_type);
        break;
    }

    printf("  Version:\t\t\t\t\t\t0x%x\n", ehdr.e_version);

    printf("  Entry point address:\t\t\t\t\t0x%x\n", ehdr.e_entry);

    printf("  Start of program headers:\t\t\t\t%d (bytes into file)\n", ehdr.e_phoff);

    printf("  Start of section headers:\t\t\t\t%d (bytes into file)\n", ehdr.e_shoff);

    printf("  Flags:\t\t\t\t\t\t0x%x\n", ehdr.e_flags);

    printf("  Size of this header:\t\t\t\t\t%d (bytes)\n", ehdr.e_ehsize);

    printf("  Size of program headers:\t\t\t\t%d (bytes)\n", ehdr.e_phentsize);

    printf("  Number of program headers:\t\t\t\t%d\n", ehdr.e_phnum);

    printf("  Size of section headers:\t\t\t\t%d (bytes)\n", ehdr.e_shentsize);

    printf("  Number of section headers:\t\t\t\t%d \n", ehdr.e_shnum);

    printf("  Section header string table index:\t\t\t%d \n", ehdr.e_shstrndx);
}

void printElfFunc(const char *fileName)
{
    FILE *fd = fopen(fileName, "rb");
  
    if (!fd)
    {
        perror("Failed to open file");
        return;
    }
    
    Elf32_Ehdr ehdr;
    fread(&ehdr, sizeof(Elf32_Ehdr), 1, fd);
    fseek(fd, ehdr.e_shoff, SEEK_SET);

    Elf32_Shdr simbolHdr;
    Elf32_Shdr stringHdr;
    uint8_t strtab = 0;
    for (size_t i = 0; i < ehdr.e_shnum; i++)
    {
        Elf32_Shdr shdr;
        fread(&shdr, sizeof(Elf32_Shdr), 1, fd);
        if (shdr.sh_type == SHT_SYMTAB)
        {
            simbolHdr = shdr;
        }
        else if (shdr.sh_type == SHT_STRTAB)
        {
            strtab++;
            if (strtab == 2)
            {
                stringHdr = shdr;
            }
        }
    }

    size_t numOfSimbols = simbolHdr.sh_size / sizeof(Elf32_Sym);
    char name[20];
    memset(name, 0, sizeof(name));

    printf("%-10s%-10s    %-10s%-20s\n", "NR", "Value", "Size", "Name");
    int pos = 0;
    for (size_t i = 0; i < numOfSimbols; i++)
    {
        fseek(fd, simbolHdr.sh_offset + i * sizeof(Elf32_Sym), SEEK_SET);
        Elf32_Sym sys;
        fread(&sys, sizeof(Elf32_Sym), 1, fd);

        if (sys.st_size > 50)
        {
            printf("%-10d", pos++);
            printf("0x%-8x    ", sys.st_value);
            printf("%-10d", sys.st_size);

            fseek(fd, stringHdr.sh_offset + sys.st_name, SEEK_SET);
            fread(&name, sizeof(name), 1, fd);

            printf("%-20s\n", name);
        }
    }

    fclose(fd);
    return;
}

void changeElf(int argc, const char **argv)
{
    FILE *fd = fopen(argv[2], "r+b");
    if (!fd)
    {
        perror("Failed to open file");
        return;
    }

    Elf32_Ehdr ehdr;
    fread(&ehdr, sizeof(Elf32_Ehdr), 1, fd);
    fseek(fd, ehdr.e_shoff, SEEK_SET);

    Elf32_Shdr simbolHdr;
    Elf32_Shdr stringHdr;
    uint8_t strtab = 0;
    for (size_t i = 0; i < ehdr.e_shnum; i++)
    {
        Elf32_Shdr shdr;
        fread(&shdr, sizeof(Elf32_Shdr), 1, fd);
        if (shdr.sh_type == SHT_SYMTAB)
        {
            simbolHdr = shdr;
        }
        else if (shdr.sh_type == SHT_STRTAB)
        {
            strtab++;
            if (strtab == 2)
            {
                stringHdr = shdr;
            }
        }
    }

    size_t numOfSimbols = simbolHdr.sh_size / sizeof(Elf32_Sym);
    char name[20];
    memset(name, 0, sizeof(name));

    printf("%-10s\t%s\t\t%s\t%s\t\n", "IME", "NASLOV", "VREDNOST", "NOVA_VREDNOST");

    for (unsigned int i = 0; i < numOfSimbols; ++i)
    {
        fseek(fd, simbolHdr.sh_offset + i * sizeof(Elf32_Sym), SEEK_SET);
        Elf32_Sym sys;
        fread(&sys, sizeof(Elf32_Sym), 1, fd);

        if (!(ELF32_ST_TYPE(sys.st_info) == STT_OBJECT && ELF32_ST_BIND(sys.st_info) == STB_GLOBAL))
            continue;

        fseek(fd, stringHdr.sh_offset + sys.st_name, SEEK_SET);
        fread(&name, sizeof(name), 1, fd);

        int con = 1;
        for (int j = 3; j < argc; j++)
        {
            if (strcmp(name, argv[j]) == 0)
            {
                con = 0;
                break;
            }
        }
        if (con)
            continue;

        printf("%-10s\t", name);
        printf("%x\t\t", sys.st_value);

        fseek(fd, ehdr.e_shoff + sys.st_shndx * sizeof(Elf32_Shdr), SEEK_SET);
        Elf32_Shdr hdr;
        fread(&hdr, sizeof(Elf32_Shdr), 1, fd);
        uint32_t realAddr = (sys.st_value - hdr.sh_addr) + hdr.sh_offset;

        fseek(fd, realAddr, SEEK_SET);
        uint32_t val;
        fread(&val, sizeof(uint32_t), 1, fd);

        printf("%x\t\t", val);

        val += 10;
        fseek(fd, realAddr, SEEK_SET);
        fwrite(&val, sizeof(val), 1, fd);
        printf("%x\n", val);
    }

    fclose(fd);
    return;
}