main.cpp

/*
 * CP Template Generator
 *
 * author: calgagi
 *         Calvin Gagliano 
 */

#include <fstream>
#include <iostream>
#include <unistd.h>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <queue>

using namespace std;

// file to be printed to target file after libraries are printed
string CP_GEN_AFTER = "./user.cpp";

// Dependency graph for libraries that require other libraries
// Note: this should be a DAG
// Syntax: {lib, {list of libs that lib is dependent on}}
map<string, vector<string>> dep_graph = {
    {"lca", {"graph", "rlamb"}}
};

// ============= Helper functions ==============
void error(string msg) {
    cout << "cp_gen: " << msg << endl;
    exit(1);
}

string noAfterDot(const string& filename) {
    int where = filename.find(".");
    if (where == string::npos) {
        error("Could not find task in filename");
    } 
    return filename.substr(0, where);
}

void shavePath(string& path) {
    while (!path.empty() && path.back() != '/') {
        path.pop_back();
    }
    return;
}

string pathToGen() {
    char buff[512];

    // Linux syscall that gets the linked path to the current executable, "gen"
    ssize_t r = ::readlink("/proc/self/exe", buff, 511);
    if (r == -1) {
        error("Could not find path to current executable."); 
    }
    else {
        buff[r] = '\0';
    }

    // this assumes that gen is in the root directory of cp_gen (where lib is)
    string gen_path = buff;
    shavePath(gen_path);
    return gen_path;
}

// ============= Output functions ==============
void output_file(fstream& new_file, const string& file_path) {
    fstream to_output;
    to_output.open(file_path);
    if (!to_output.is_open()) {
        error("Could not find " + file_path + " file");
    }
    string line;
    while (getline(to_output, line)) {
        // Skip "#pragma once" lines, they are used for dependencies in testing
        if (line != "#pragma once") {
            new_file << line << endl;
        }
    }
    return;
}

void output_templates(fstream& new_file, const vector<string>& templates) {
    // this assumes that gen is in the root directory of cp_gen (where lib is)
    string gen_path = pathToGen();
    gen_path += "lib/";

    set<string> already_outputted;

    for (const string& ds : templates) {
        vector<string> to_output;

        queue<string> q;
        q.push(ds);

        // perform BFS on dependency graph
        while (!q.empty()) {
            string cur_lib = q.front();
            q.pop();
            if (already_outputted.find(cur_lib) != already_outputted.end()) {
                continue;
            }
            already_outputted.insert(cur_lib);
            to_output.push_back(cur_lib);
            for (const string& dep : dep_graph[cur_lib]) {
                q.push(dep);
            }
        }
        
        // output files in reverse visited order
        for (int i = to_output.size() - 1; ~i; i--) {
            output_file(new_file, gen_path + to_output[i] + ".hpp");
            new_file << endl;
        }
    }

    return;
}

void output(fstream& new_file, const string& filename, const vector<string>& templates) {
    // Static Header
    time_t now = time(0);
    new_file << "/*\n"
        " * generated by github.com/calgagi/cp_gen\n" 
        " * file: " << filename << "\n"
        " * time: " << ctime(&now) << ""
        " */\n"
        "\n"
        "#include <bits/stdc++.h>\n"
        "using namespace std;\n"
        "typedef long long ll;\n"
        "typedef long double ld;\n\n"
        "namespace cp {\n\n";


    string gen_path = pathToGen();

    // Output templates
    output_templates(new_file, templates);
    new_file << "}\n\n"
                "/* ===== BEGIN USER CODE ===== */\n\n";
    // User-defined after cp namespace file
    output_file(new_file, gen_path + CP_GEN_AFTER);

    return;
}

// =============== main ================
int main(int argc, char** argv) {
    ios_base::sync_with_stdio(false);  
    cin.tie(NULL);

    char cwdBuf[10000];
    string cwd = "";
    if (getcwd(cwdBuf, sizeof(cwdBuf)) == NULL) {
        error("Could not get current working directory");
    } 
    else {
        cwd = cwdBuf;
    }

    // Parse CLI arguments
    vector<string> cliArgs;
    string filename = "";
    for (int i = 1; i < argc; i++) {
        cliArgs.push_back(argv[i]);
        if (cliArgs.back()[0] != '-') {
            // we've found our filename
            filename = cliArgs.back();
            cliArgs.pop_back();
        }
        else {
            // remove leading '-'
            cliArgs.back().erase(cliArgs.back().begin());
        }
    }

    if (filename == "") {
        error("Could not find filename");
    }

    string path = cwd + "/" + filename;
    fstream new_file;
    new_file.open(path, ios_base::out);
    if (!new_file.is_open()) {
        error("Could not open file for output");
    }

    output(new_file, filename, cliArgs);

    return 0;
}