#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ptrace.h>

#include "linenoise.h"
#include "mujs.h"

#define LOG_ERR(fmt, ...) fprintf(stderr, "Error: " fmt, ##__VA_ARGS__)
#define LOG_INF(fmt, ...) fprintf(stdout, "Info:  " fmt, ##__VA_ARGS__)

#define unused(x) ((void)(x))

#define shift(argc, argv, msg, ...) (argc <= 0 ? (LOG_ERR(msg, ##__VA_ARGS__), exit(EXIT_FAILURE)) : (void)0, argc--, *argv++)

typedef struct {
    const char *file;
    pid_t pid;
    js_State *js;
} Dbg;

void dbg_js_print_file(js_State *js)
{
    void *data = js_currentfunctiondata(js);
    Dbg *dbg = (Dbg *)data;

    printf("File: %s\n", dbg->file);
}

void dbg_init_js(Dbg *dbg)
{
    dbg->js   = js_newstate(NULL, NULL, JS_STRICT);

    js_newcfunctionx(dbg->js, &dbg_js_print_file, "print_file", 0, dbg, NULL);
    js_setglobal(dbg->js, "print_file");
}

void dbg_init(Dbg *dbg, const char *file, pid_t pid)
{
    dbg->file = file;
    dbg->pid  = pid;
    dbg_init_js(dbg);
}

void dbg_deinit(Dbg *dbg)
{
    js_freestate(dbg->js);
}

void dbg_loop(Dbg *dbg)
{
    int status, options = 0;
    waitpid(dbg->pid, &status, options);

    char *line = NULL;
    while ((line = linenoise("debugus # ")) != NULL) {
        js_dostring(dbg->js, line);
        linenoiseHistoryAdd(line);
        linenoiseFree(line);
    }
}

void start_debugging(const char *input_file_path)
{
    pid_t pid = fork();
    if (pid == 0) {
        /* ptrace(PTRACE_TRACEME, 0, NULL, NULL); */
        /* execl(input_file_path, input_file_path, NULL); */
    } else if (pid >= 1) {
        Dbg dbg;
        dbg_init(&dbg, input_file_path, pid);
        dbg_loop(&dbg);
        dbg_deinit(&dbg);
    }
}

int main(int argc, char ** argv)
{
    const char *program_name = shift(argc, argv, "");
    unused(program_name);

    const char *input_file_path = shift(argc, argv, "No input file provided\n");
    start_debugging(input_file_path);

    return 0;
}