#!/usr/bin/c -Wall -Wextra -std=c99 -O2 --
#define _XOPEN_SOURCE 700
#include <time.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <alloca.h>
#include <string.h>
#include "str_replace.h"

#define ROOT "https://blog.notryan.com"

void p_tag(unsigned indent, char *tag, char *str) {
    while (indent--) putchar(' ');
    printf("<%s>%s</%s>\n", tag, str, tag);
}

#define RFC5322_FMT "%a, %d %b %Y %T %z"
size_t rfc5322_date(struct tm *tm, char *buf, size_t len) {
    //setenv("TZ", "PST8PDT", 1); tzset();
    return strftime(buf, len, RFC5322_FMT, tm);
}

void get_datetime_str(char *fname, char *pub_date) {
    int fd = open(fname, O_RDONLY);

    // Date
    char date[17];
    lseek(fd, 143, 0);
    read(fd, date, sizeof(date));
    date[sizeof(date)-1] = '\0';

    // Time
    char time_[15];
    lseek(fd, 225, 0);
    read(fd, time_, sizeof(time_));
    time_[sizeof(time_)-1] = '\0';

    // Append and parse
    close(fd);
    sprintf(pub_date, "%s %s", date, time_);
}

void p_item(unsigned index) {
    // Read item contents. Skip if DNE.
    char fname[8];
    sprintf(fname, "%03u.txt", index);
    if (access(fname, R_OK) == -1) return;

    // Read date
    char pub_date[64];
    get_datetime_str(fname, pub_date);

    // Read title
    char title[80];
    FILE *fp = fopen(fname, "r");
    fseek(fp, 240, 0);
    while (fgetc(fp) == ' ');
    fseek(fp, -1, SEEK_CUR);
    fgets(title, 80, fp);
    title[strlen(title)-1] = '\0';
    fseek(fp, 0, 0);
    
    // Generate body
    char *desc = malloc(100);
    desc[0] = '\0';
    strcat(desc, "<![CDATA[<pre>\n");
    int i = 2;
    char buf[100];
    while (fgets(buf, 100, fp)) {
        char *escaped = escape_html(buf);
        desc = realloc(desc, 100*i++);
        strcat(desc, escaped);
        free(escaped);
    }
    fclose(fp);
    strcat(desc, "</pre>]]>");

    // Generate title
    char link[80];
    sprintf(link, ROOT"/%s", fname);

    puts("\n    <item>");
    p_tag(8, "title", title);
    p_tag(8, "link",  link);
    p_tag(8, "description", desc);
    p_tag(8, "pubDate", pub_date);
    printf("        <guid isPermaLink=\"false\">%s</guid>\n", fname);
    puts("    </item>");

    free(desc);
}

int main(void) {
    char build_date[64];
    time_t tm = time(NULL);
    rfc5322_date(localtime(&tm), build_date, sizeof(build_date));

    puts("<?xml version=\"1.0\" encoding=\"UTF-8\" ?>");
    puts("<rss version=\"2.0\" xmlns:atom=\"http://www.w3.org/2005/Atom\">");
    puts("<channel>");
    puts("<atom:link href=\""ROOT"/rss.xml\" rel=\"self\" type=\"application/rss+xml\"/>");
    p_tag(4, "title", "notryan - blog");
    p_tag(4, "link", ROOT);
    p_tag(4, "description", "A text-only blog about technology... and stuff.");
    printf("\n");
    p_tag(4, "generator", ROOT"/rss.c");
    p_tag(4, "lastBuildDate", build_date);
    for (int i = 1; i < 1000; i++) p_item(i);
    puts("</channel>");
    puts("</rss>");

    return 0;
}