import { createRequire } from 'module';
const require = createRequire(import.meta.url)
const config = require("../config.json")
const fs = require('fs')
const locale = require(`../locales/${config.locale}.json`)

// This function requires a module without caching it
// So the server doesn't need to be restarted, though this can slow it down a bit.
// https://stackoverflow.com/a/16060619
export function require_module(module) {
    if (config.cache_data == false) {
        delete require.cache[require.resolve(module)];
        return require(module);
    }
    else {
        return require(module);
    }
}

// The configuration defines a date format using the date-fns (a datetime library) syntax 
// eg "yyyy-MM-dd"
// this converts unix time (an integer) into a string that is formatted according to config.js
// uses date-fns's fromUnixTime() and format() functions
// returns the formatted date (string)
export function unix_time_to_date_format(unix_time) {
    const { fromUnixTime, format, getUnixTime } = require("date-fns") // A date utility library
	let date = fromUnixTime(unix_time)
	let formatted_date = format(date, config.date_format)
	return formatted_date
}
// This is similar to the above function, however, instead of formatting to the users
// configuration, it formats to RFC-822 which is the date format used by RSS feeds
// eg "Mon, 23 May 2025 18:59:59 +0100"
// accepts unix time (int)
// returns the formatted date (string)
export function unix_time_to_rss_date(unix_time) {
    const { fromUnixTime, format, getUnixTime } = require("date-fns") // A date utility library
	let date = fromUnixTime(unix_time)
	let formatted_date = format(date, "EEE, dd MMM yyyy HH:mm:ss")
	return `${formatted_date} ${config.time_zone}`
}
// And again with atom's date format
export function unix_time_to_atom_date(unix_time) {
    const { fromUnixTime, format, getUnixTime } = require("date-fns") // A date utility library
	let date = fromUnixTime(unix_time)
	let formatted_date = format(date, "yyyy-MM-dd'T'HH:mm:ss'Z'")
	return `${formatted_date}`
}
// This function accepts a list of strings eg ["string1","string2,"string3"] (any length)
// then returns a string of them each pointing to a seperate url
// eg "<a href="/tag/string1">string1</a>, <a href="/tag/string2">string2</a>, <a href="/tag/string3">string3</a>"
// this is so you can have a list of tags that each point to their individual tag page
// returns: string
export function render_tags(tags) {
	let string = "" // Initialises the string
    if (tags.length == 1 && tags[0] == "") {
        string = locale.no_tags; // If there are no tags, output something
    }
    else {
        for (let tag_index = 0; tag_index < tags.length; tag_index++) { // Loop over each tag
            string += `<a href="/tag/${tags[tag_index].trim()}">${tags[tag_index].trim()}</a>` // Adds the tag to the string as a HTML href
            if (tag_index < tags.length - 1) { // If there are more tags, then insert a comma
                string += ", ";
            }
        }
    }
	return string
}
// The users are stored as a list of objects [ user_object, user_object, user_object ]
// So you cannot easily find the userID (position in list) from the username
// This function returns the username for a given userID by looping over every user
// if the user is present, it returns the index of the user (integer)
// if the user is not present it returns -1
export function get_userID(username) {
    const users = require("../data/users.json")
	for (let i = 0; i < users.length; i++) { // Loop over every user
		if (users[i]['username'] == username) {
			return i // If the username matches then return the index of that user
		}
	}
	return -1 // If user is not present, return -1
}

// This escapes some potentially dangerous HTML characters with their HTML entities
// https://www.freeformatter.com/html-entities.html
// accepts a string
// returns a string with some character replaced by their entities
export function escape_input(input) {
    let output = input
        .replaceAll("&", "&amp;") // This must be first
        .replaceAll("<", "&lt;")
        .replaceAll(">", "&gt;")
        .replaceAll("\\", "&#92;")
        .replaceAll('"', "&#34;")
        .replaceAll("'", "&#39;")
        .replaceAll("/", "&#47;")
        .replaceAll("%", "&#37;")
    return output
}

// Render comment content by replacing the >> int with a url link to that comment
// Syntax: ">> postID-commentID"
export function render_comment(comment_content) {
    return comment_content
            .replaceAll(/>> ([0-9]*)-([0-9]*)/g, "<a href='/comment/$1-$2'>>> $1-$2</a>")
            .replaceAll(/>>([0-9]*)-([0-9]*)/g, "<a href='/comment/$1-$2'>>>$1-$2</a>")
            .replaceAll(/&gt;&gt; ([0-9]*)-([0-9]*)/g, "<a href='/comment/$1-$2'>>> $1-$2</a>")
            .replaceAll(/&gt;&gt;([0-9]*)-([0-9]*)/g, "<a href='/comment/$1-$2'>>>$1-$2</a>")
            .replaceAll("\n", "<br/>")

};

// Renders a string into markdown using markdown-it library
export function render_md(content) {
    const markdownit = require("markdown-it")
    const md = markdownit({ // this is just defining some options for markdown-it, should I add this to config.json?
        html: false,
        xhtmlOut: false,
        breaks: true,
        linkify: false,
        typographer: true,
        quotes: locale.quotes,
    })
    return md.render(content)
};