#include <string>
#include <iostream>
#include <filesystem>
#include <vector>
#include <chrono>

#include <string.h>

std::string libs = "";
std::string cppflags = "";
std::string executable = "out";
std::string source_path = "";
std::string build_path = "";

std::vector<std::string> keys = {"libs", "cppflags", "executable", "sourcepath", "buildpath"};
enum tokens {LIBS, CPPFLAGS, EXECUTABLE, SOURCEPATH, BUILDPATH};

bool must_link = false;

char *getBufferFromFile(const char* filename)
{
    FILE *f = fopen(filename, "rb");
    fseek(f, 0, SEEK_END);
    long size = ftell(f);
    fseek(f, 0, SEEK_SET);
    char *buffer = (char*)malloc(size+1);
    fread(buffer, size, 1, f);
    buffer[size] = 0;
    return buffer;
}

#define IGNOREWHITESPACE while (*p!=0 && *p <= 32) { p++; }
void loadLagueirtoFile()
{
    char *buffer = getBufferFromFile("lagueirtofile");
    char *p = buffer;
    char token[255];
    while (*p!=0)
    {
        IGNOREWHITESPACE;  // Ignore whitespace
        int i=0;
        while (*p>32 && *p!='=') { token[i]=*p; i++; p++; }
        IGNOREWHITESPACE
        if (*p=='=')
        {
            token[i]=0;
            int tokennum = -1;
            for (int j=0;j<keys.size();++j) if (keys[j]==token) tokennum = j;
            if (tokennum!=-1)
            {
                p++;
                IGNOREWHITESPACE
                i=0;
                while (*p!='\r' && *p!='\n' && *p!=0) { token[i]=*p; i++; p++; }
                token[i]=0;
                switch (tokennum)
                {
                    case LIBS:
                        libs = token;
                        //std::cout << "LIBS: " << libs << std::endl;
                        break;
                    case CPPFLAGS:
                        cppflags = token;
                        //std::cout << "CPPFLAGS: " << cppflags << std::endl;
                        break;
                    case EXECUTABLE:
                        executable = token;
                        //std::cout << "EXECUTABLE: " << executable << std::endl;
                        break;
                    case SOURCEPATH:
                        source_path = token;
                        //std::cout << "SOURCEPATH: " << source_path << std::endl;
                        break;
                    case BUILDPATH:
                        build_path = token;
                        //std::cout << "BUILDPATH: " << build_path << std::endl;
                        break;
                }
            }
        }
    }
    free(buffer);
}

std::string getFileExtension(std::string path)
{
    std::size_t dotpos = path.find_last_of(".");
    return dotpos <= 0 ? "" : path.substr(dotpos + 1);
}

std::string getFileNameWithoutExtension(std::string path)
{
    std::size_t slashpos = path.find_last_of("/");
    std::string filename = path.substr(slashpos+1);

    std::size_t dotpos = filename.find_last_of(".");
    if (dotpos <= 0) return filename;

    return filename.substr(0, dotpos);
}


const bool textFound(char *buffer, const char *text)
{
    const int strsize = strlen(text);
    int i = 0;
    bool equal=true;
    while (equal && i<strsize)
    {
        if (buffer[i]!=text[i]) equal = false;
        ++i;
    }
    return equal;
}


std::vector<std::string> getIncludes(std::string filename)
{
    char *buffer = getBufferFromFile(filename.c_str());

    std::vector<std::string> includes;

    char *p = buffer;
    while (*p != 0)
    {
        if (*p=='#')
        {
            if (textFound(buffer, "#include"))
            {
                p+=8;
                while(strchr(" \t", *p)) p++;   // Ignore whitespace (spaces and tabs)
                if (*p == '"')
                {
                    p++;
                    char *p2 = p;
                    while (*p2!='"' && *p2!=0 ) p2++;
                    if (*p2!=0) {
                        *p2=0;
                        includes.push_back(std::string(p));
                        p = p2+1;
                    }
                }
            }
        }
        p++;
    }
    
    free(buffer);
    return includes;
}

std::vector<std::string> split(std::string str)
{
    std::vector<std::string> strings;
    char tmp[100];
    int tmp_p = 0, str_p = 0;
    while (str[str_p]!=0)
    {
        if (str[str_p]!=32)
            tmp[tmp_p++] = str[str_p++];
        else
        {
            tmp[tmp_p]=0;
            strings.push_back(tmp);
            tmp_p=0; while (str[str_p]==32) str_p++;
        }
    }
    tmp[tmp_p]=0;
    strings.push_back(tmp);
    
    return strings;
}

void MaybeRecompile(std::string source_file)
{
    bool must_recompile = false;
    std::string object_file = build_path + "/" + getFileNameWithoutExtension(source_file)+".o";

    // si el objecte no existeix, fa falta recompilar
    if (!std::filesystem::exists(object_file))
    {
        must_recompile = true;
        //std::cout << "'" << object_file << "' No existeix. ";

    }
    else
    {
        // Si sí que existeix, agafem la data de modificació
        auto object_file_write_time = std::filesystem::last_write_time(object_file);
        
        // Si la data de modificació del cpp es major que la del objecte, fa falta recompilar
        auto source_file_write_time = std::filesystem::last_write_time(source_file);
        if (source_file_write_time > object_file_write_time)
        {
            //std::cout << "'" << source_file << "' es més nou. ";
            must_recompile = true;
        }
        else
        {
            // Sino, mirem els includes
            auto include_files = getIncludes(source_file);
            for (auto include : include_files)
            {
                std::filesystem::path fullpath(source_file);
                auto path_without_filename = fullpath.remove_filename(); 
                std::string src_path = path_without_filename.string();

                std::string include_file = src_path + "/" + include;
                if (!std::filesystem::exists(include_file))
                {
                    std::cout << "WARNING: Include file '" << include_file << "' not found." << std::endl;
                }
                else
                {
                    auto include_file_write_time = std::filesystem::last_write_time(include_file);
                    if (include_file_write_time > object_file_write_time)
                    {
                        //std::cout << "El include '" << include_file << "' es més nou. ";
                        must_recompile = true;
                        break;
                    }
                }
            }

        }
    }
    if (must_recompile)
    {
        must_link = true;
        //std::cout << object_file << " s'ha de reompilar" << std::endl;
        std::string command = "g++ " + source_file + " " + cppflags + " -c -o " + object_file;
        std::cout << command << std::endl;

        std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
        system(command.c_str());
        std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
        float t = float(std::chrono::duration_cast<std::chrono::microseconds>(end - begin).count())/1000000;
        std::cout << "(" << t << " seconds)" << std::endl;
    }
    else
    {
        //std::cout << object_file << " està actualitzat" << std::endl;
    }
}

int main(int argc, char *argv[])
{
    if (argc>1) {
        for (int i=1; i<argc; ++i) {
            if (argv[i][0] == '-') {
                if (strcmp(argv[i], "--clean")==0) {
                    system("rm -rf build");
                }
            } else {
                std::filesystem::current_path(argv[i]);
            }
        }
    }
    
    loadLagueirtoFile();

    std::chrono::steady_clock::time_point begin_all = std::chrono::steady_clock::now();

    if (!std::filesystem::is_directory(build_path))
    {
        std::filesystem::create_directory(build_path);
    }

    auto source_paths = split(source_path);

    for (auto src_path : source_paths)
    {
        if (!std::filesystem::is_directory(src_path))
        {
            if (std::filesystem::is_regular_file(src_path) && getFileExtension(src_path)=="cpp")
            {
                MaybeRecompile(src_path);
            } else {
                std::cout << "ERROR: '" << src_path <<"' does not exists." << std::endl;
                exit(1);
            }
        } else {
            std::string path = "./" + src_path;
            for (const auto & entry : std::filesystem::directory_iterator(path))
            {
                std::string source_file = entry.path();
                std::string file_extension = getFileExtension(source_file);
                if (file_extension=="cpp" || file_extension=="c")
                {
                    MaybeRecompile(source_file);
                }
            }
        }
    }

    if (must_link)
    {
        std::string command = "g++ " + build_path + "/*.o " + libs + " -o " + executable;
        std::cout << command << std::endl;
        if (system(command.c_str()) != 0) {
            std::cout << "ABORTED!" << std::endl;
            exit(1);
        }
        std::chrono::steady_clock::time_point end_all = std::chrono::steady_clock::now();
        float t = float(std::chrono::duration_cast<std::chrono::microseconds>(end_all - begin_all).count())/1000000;
        std::cout << "(" << t << " seconds)" << std::endl;
    }
    else
    {
        std::cout << "Everything is up to date. Nothing to do." << std::endl;
    }
}