// SPDX-License-Identifier: 0BSD
// Copyright © Paweł Redman


#let webroot = "/"

#let format-date-en(date) = {
    let months = (
        "January",
        "February",
        "March",
        "April",
        "May",
        "June",
        "July",
        "August",
        "September",
        "October",
        "November",
        "December",
    )

    [#months.at(date.month() - 1) #date.day(), #date.year()]
}

#let link-self(page, body) = {
    let parts = page.split("#")
    let url = if parts.len() == 1 {
        webroot + page + ".html"
    } else {
        webroot + parts.at(0) + ".html#" + parts.slice(1).join("#")
    }

    link(url, body)
}

#let static(path) = {
    webroot + "static/" + path
}

#let img(src, alt: "") = {
    html.elem("img", attrs: (src: src, alt: alt))
}

#let anchor(name) = {
    html.elem("span", attrs: (id: name))[]
}

#let breadcrumbs() = {
    let path = sys.inputs.at("path")
    let parts = path.split("/")

    link(webroot)[redman.xyz]

    for (i, part) in parts.enumerate() {
        let is_last = i == parts.len() - 1
        let url = parts.slice(0, i + 1).join("/") + "/index.html"

        if is_last {
            " / "
            part
        } else {
            " / "
            link(webroot + url, part)
        }
    }
}

#let template(title, header, main, front_page: false) = {
    let body_attrs = if front_page {
        (class: "front-page")
    } else {
        (:)
    }

    html.html({
        html.head({
            html.meta(charset: "utf-8")
            html.meta(name: "viewport", content: "width=device-width, initial-scale=1")
            html.title(title)
            html.link(rel: "stylesheet", href: static("style.css"))
        })
        html.elem("body", attrs: body_attrs, {
            html.header(header)
            html.main(main)
            html.footer[
                © 2019--2026 Paweł Redman \
                Text and images are licensed under #link("https://creativecommons.org/licenses/by-sa/4.0/")[CC-BY-SA 4.0] unless noted otherwise.
            ]
        })
    })
}

#let post(body, title: none, author: "Paweł Redman", date: none, updated: none) = {
    set document(
        title: title,
        author: author,
    )

    set text(lang: "en")
    set heading(numbering: "1.1.")
    set math.equation(numbering: "(1.)")

    // As of 0.14, equations aren't supported in HTML. Emit them as SVG instead.
    show math.equation: it => context {
        show: if it.block { it => it } else { box }
        if it.block {
            html.elem("div", attrs: (class: "block-math"))[
                #html.frame(it)
            ]
        } else {
            html.frame(it)
        }
    }

    if date != none {
        [
            #metadata((
                title: title,
                date_year: date.year(),
                date_month: date.month(),
                date_day: date.day(),
            )) <post-meta>
        ]
    } else {
        [
            #metadata((
                title: title,
            )) <post-meta>
        ]
    }

    template(
        title,
        html.nav(breadcrumbs()),
        html.article({
            html.header({
                html.h1(title)
                if date != none {
                    html.p(id: "author")[
                        by #author, published on #html.time(datetime: date)[#format-date-en(date)]
                        #if updated != none {
                            [, updated on #html.time(datetime: updated)[#format-date-en(updated)]]
                        }
                    ]
                }
            })
            body
        }),
    )
}