#import "pdf.typ": pdf-layout, pdf-header, code-theme
#import "metadata.typ": page, post, authors, author-text, format-date, date-key, normalize-page
#import "blog.typ": post-header, post-card
#import "color/rose-pine.typ": rose-pine
#import "color/rose-pine-moon.typ": rose-pine-moon
#import "color/rose-pine-dawn.typ": rose-pine-dawn

#let plain(value) = {
  if value == none { return "" }
  if type(value) == str { return value }
  if type(value) != content { return str(value) }
  if value == [ ] { return " " }
  if value.func() == parbreak or value.func() == linebreak { return "\n" }
  if value.has("text") { return value.text }
  if value.has("children") { return value.children.map(plain).join() }
  if value.has("body") { return plain(value.body) }
  if value.has("child") { return plain(value.child) }
  ""
}

#let escape(value) = (plain(value)
  .replace("&", "&")
  .replace("<", "&lt;")
  .replace(">", "&gt;")
  .replace("\"", "&quot;")
  .replace("'", "&apos;"))

#let tag(name, value) = "<" + name + ">" + escape(value) + "</" + name + ">\n"

#let site-context = state("typst_web_magic-context", none)

#let image(file, source: none, alt: "", width: auto) = [
  #metadata((kind: "post-image", path: file, alt: alt))
  #context {
    if target() == "html" {
      html.img(class: "post-image", src: "/assets/" + file, alt: alt, loading: "lazy", decoding: "async")
    } else {
      let resolved = if source != none { source } else {
        let ctx = site-context.get()
        assert(ctx != none, message: "Outside a site, pass source: path(...) to image")
        let asset = ctx.assets.find(item => item.path == "assets/" + file)
        assert(asset != none, message: "Image not found in assets: " + file)
        asset.source
      }
      std.image(resolved, alt: alt, width: width)
    }
  }
]

#let audio(file) = context {
  if target() == "html" {
    html.audio(
      controls: true,
      src: "/assets/" + file,
    )
  }
}

#let header(ctx) = context {
  if ctx.page.collection == "blog" {
    post-header(ctx)
  } else if target() == "html" {
    html.elem("header", attrs: (class: "page-header"))[
      #html.h1(ctx.page.title)
      #if ctx.page.date != none {
        html.p(ctx.page.date.display("[month repr:long] [day], [year]"))
      }
    ]
  } else {
    pdf-header(ctx)
  }
}

#let html-layout(ctx, body) = html.main((ctx.site.theme.header)(ctx) + body)

#let preview-layout(ctx) = [
  #set std.page(width: 600pt, height: 315pt, margin: 30pt)
  #set text(size: 32pt)
  #ctx.page.title
  #parbreak()
  #text(size: 16pt, ctx.site.title)
]

#let default-theme = (
  html: html-layout,
  pdf: pdf-layout,
  preview: preview-layout,
  header: header,
)

#let pdf(title: "", description: none, author: (), date: none, theme: (:), body) = {
  let theme = default-theme + theme
  let entry = normalize-page(page(title: title, description: description, author: author, date: date), (:))
  let ctx = (site: entry + (theme: theme), page: entry, pages: (entry,))
  set document(title: title, description: description, author: entry.author, date: date)
  (theme.pdf)(ctx, body)
}

#let listing(collection: none, render: none) = context {
  let ctx = site-context.get()
  let entries = ctx.pages
    .filter(entry => collection == none or entry.collection == collection)
    .sorted(key: date-key)
    .rev()

  for entry in entries {
    if render != none {
      render(ctx, entry)
    } else if target() == "html" {
      html.elem("article", attrs: (class: "listing-item"))[
        #html.h2(html.a(href: entry.href, entry.title))
        #if entry.description != none { html.p(entry.description) }
      ]
    } else {
      list.item(link(entry.url, entry.title))
    }
  }
}

#let post-index(collection: "blog", render: post-card) = [
  #context {
    if target() == "html" {
      html.div(class: "post-index", listing(collection: collection, render: render))
    } else {
      listing(collection: collection, render: render)
    }
  }
]

#let prepare-page(config, item) = {
  let entry = normalize-page(item.entry, (
    title: config.title,
    description: config.description,
    author: config.author,
    pdf: config.pdf,
    preview: config.preview,
  ))
  let path = if entry.path == none { item.path } else { entry.path }
  assert(
    path.ends-with(".html") and not path.starts-with("/") and not path.split("/").contains(".."),
    message: "Page paths must be relative .html paths",
  )

  let href = "/" + if path == "index.html" { "" } else if path.ends-with("/index.html") {
    path.slice(0, -10)
  } else { path }
  let stem = path.slice(0, -5)
  (
    ..entry,
    body: item.body,
    path: path,
    href: href,
    url: config.url + href,
    pdf-path: if entry.pdf { stem + ".pdf" },
    preview-path: if entry.preview { "assets/previews/" + stem + ".png" },
  )
}

#let html-document(ctx, body, feeds) = {
  let config = ctx.site
  let entry = ctx.page
  html.html(lang: config.lang)[
    #html.head[
      #html.meta(charset: "utf-8")
      #html.meta(name: "viewport", content: "width=device-width, initial-scale=1")
      #html.title(plain(entry.title))
      #html.meta(name: "description", content: plain(entry.description))
      #html.link(rel: "canonical", href: entry.url)
      #for (property, value) in (
        "og:title": plain(entry.title),
        "og:description": plain(entry.description),
        "og:url": entry.url,
        "og:type": if entry.collection == none { "website" } else { "article" },
      ) {
        html.elem("meta", attrs: (property: property, content: value))
      }
      #if entry.preview {
        html.elem("meta", attrs: (
          property: "og:image",
          content: config.url + "/" + entry.preview-path,
        ))
        html.meta(name: "twitter:card", content: "summary_large_image")
      }
      #for stylesheet in config.css { html.link(rel: "stylesheet", href: stylesheet) }
      #for feed in feeds {
        html.link(rel: "alternate", type: "application/rss+xml", title: feed.title, href: "/" + feed.path)
      }
      #(config.head)(ctx)
    ]
    #html.body((config.theme.html)(ctx, body))
  ]
}

#let rss(config, entries, feed) = {
  let xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<rss version=\"2.0\"><channel>\n"
  xml += tag("title", feed.title) + tag("link", config.url) + tag("description", config.description)

  for entry in entries.sorted(key: date-key).rev() {
    xml += "<item>\n" + tag("title", entry.title) + tag("link", entry.url)
    xml += "<guid isPermaLink=\"true\">" + escape(entry.url) + "</guid>\n"
    xml += tag("description", entry.description)
    if entry.date != none {
      let date = entry.date.display("[weekday repr:short], [day padding:zero] [month repr:short] [year]")
      xml += tag("pubDate", date + " 00:00:00 +0000")
    }
    xml += "</item>\n"
  }
  asset(feed.path, xml + "</channel></rss>\n")
}

#let sitemap(entries) = {
  let urls = entries.filter(entry => entry.path != "404.html").map(entry => {
    "<url>" + tag("loc", entry.url) + "</url>\n"
  })
  asset("sitemap.xml",
    "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
    + "<urlset xmlns=\"http://www.sitemaps.org/schemas/sitemap/0.9\">\n"
    + urls.join() + "</urlset>\n",
  )
}

#let site(
  title: "",
  url: "",
  description: none,
  author: (),
  lang: "en",
  css: auto,
  head: ctx => [],
  pdf: false,
  preview: false,
  theme: (:),
  pages: (),
  assets: (),
  feeds: (),
) = {
  let default-css = "assets/typst_web_magic.css"
  if css == auto { css = ("/" + default-css,) }
  if css.contains("/" + default-css) and not assets.any(item => item.path == default-css) {
    assets.push((path: default-css, source: path("default.css")))
  }
  let config = (
    title: title,
    url: url.trim(at: end, "/"),
    description: description,
    author: author,
    by: authors(author),
    lang: lang,
    css: css,
    head: head,
    pdf: pdf,
    preview: preview,
    theme: default-theme + theme,
  )
  let entries = pages.map(item => prepare-page(config, item))
  let outputs = assets.map(item => item.path) + feeds.map(feed => feed.path) + ("sitemap.xml",)
  for entry in entries {
    outputs += (entry.path, entry.pdf-path, entry.preview-path).filter(path => path != none)
  }
  assert(outputs.len() == outputs.dedup().len(), message: "Duplicate output paths")

  for entry in entries {
    let ctx = (site: config, page: entry, pages: entries, assets: assets)
    let content = [
      #site-context.update(ctx)
      #entry.body
    ]
    let metadata = (
      title: entry.title,
      description: entry.description,
      author: entry.author,
      date: entry.date,
    )

    document(entry.path, ..metadata, html-document(ctx, content, feeds))
    if entry.pdf {
      document(entry.pdf-path, ..metadata, (config.theme.pdf)(ctx, content))
    }
    if entry.preview {
      document(entry.preview-path, ..metadata, (config.theme.preview)(ctx))
    }
  }

  for item in assets { asset(item.path, read(item.source, encoding: none)) }
  for feed in feeds {
    let render = feed.at("render", default: rss)
    render(config, entries.filter(entry => entry.collection == feed.collection), feed)
  }
  sitemap(entries)
}