#define _GNU_SOURCE

#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>

#include "arg.h"

char *argv0;

int execveat(int dirfd, const char *path,
            char *const argv[],
            char *const envp[],
            int flags);

void die(const char *fmt, ...)
{
	va_list ap;
	int saved_errno;

	saved_errno = errno;

	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);

	if (fmt[0] && fmt[strlen(fmt)-1] == ':')
		fprintf(stderr, " %s", strerror(saved_errno));
	fputc('\n', stderr);

	exit(1);
}

#define usage() die("Usage: %s [filename]", argv0)
int main(int argc, char **argv)
{
    ARGBEGIN {
        default:
            usage();
    } ARGEND

    if(argc < 1)
        usage();

    int cpwd = open(".", O_PATH | O_CLOEXEC);

    int file = open(*argv, 0);
    if(file < 0)
        die("open file:");

    char buf[1 << 8];
    size_t linksize = readlink("/proc/self/exe", buf, 1 << 8);
    if(linksize < 0)
        die("readlink:");
    buf[linksize] = '\0';
    char *dname = dirname(buf);
    chdir(dname);

    int mkcpio = open("gen_init_cpio", O_CLOEXEC);
    if(mkcpio < 0)
        die("open gen_init_cpio:");

    fchdir(cpwd);

    char *argv0_dirname = strdup(*argv);
    chdir(dirname(argv0_dirname));
    free(argv0_dirname);

    int cpiopipe[2];
    if(pipe(cpiopipe) < 0)
        die("pipe:");

    int materialfd = memfd_create("material.mtl", 0);
    if(materialfd < 0)
        die("memfd_create:");

    int stdout_kept = dup(STDOUT_FILENO);
    dup2(cpiopipe[0], STDIN_FILENO);
    dup2(cpiopipe[1], STDOUT_FILENO);
    //dup2(STDOUT_FILENO, materialpipe[1]);
    if(cpiopipe[0] != STDIN_FILENO)
        close(cpiopipe[0]);
    if(cpiopipe[1] != STDOUT_FILENO)
        close(cpiopipe[1]);
    /* all printf go to gen_init_cpio now */

    printf("file material.mtl /proc/self/fd/%d 0644 0 0\n", materialfd);
    size_t num_read = 1;
    while(num_read > 0) {
        buf[0] = '\0';
        num_read = read(file, buf, (1 << 8) - 2);
        lseek(file, -num_read, SEEK_CUR);
        buf[num_read] = '\0';
        *strchrnul(buf, '\n') = '\0';
        lseek(file, strchrnul(buf, '\n') - buf + 1, SEEK_CUR);
        if(strncmp(buf, "map_", 4) == 0 ||
                strncmp(buf, "disp ", 5) == 0 ||
                strncmp(buf, "bump ", 5) == 0) {
            char *name = *argv;
#define CASE(val) strncmp(buf, val, strlen(val)) == 0
            if(CASE("map_Ka "))
                name = "ambient";
            else if(CASE("map_Kd "))
                name = "diffuse";
            else if(CASE("map_Ks "))
                name = "specular";
            else if(CASE("map_Ns "))
                name = "specular_highlight";
            else if(CASE("map_bump ") || CASE("bump"))
                name = "bump";
            else if(CASE("disp "))
                name = "displacement";
            else if(CASE("map_d "))
                name = "alpha";

            *strchrnul(buf, ' ') = '\0';
            dprintf(materialfd, "%s %s\n", buf, name);

            printf("file %s %s 0644 0 0\n", name, strchrnul(buf, ' ') + 1);
        } else {
            dprintf(materialfd, "%s\n", buf);
        }
    }
    fflush(stdout);
    dup2(stdout_kept, STDOUT_FILENO);
    if(stdout_kept != STDOUT_FILENO)
        close(stdout_kept);

    execveat(mkcpio, "", (char*[]){"gen_init_cpio", "-", NULL}, NULL, AT_EMPTY_PATH);
}