// report.typ — mopac-pdf "report" template: clean business report with
// title page, TOC, numbered headings, headers/footers with classification.
#let report(
  title: "Untitled",
  subtitle: "",
  author: "",
  date: "",
  classification: "",
  doc,
) = {
  let accent = rgb("#1f4e79")
  let ink = rgb("#1a1a1a")
  let rule = luma(205)

  set page(
    paper: "a4",
    margin: (top: 2.6cm, bottom: 2.6cm, x: 2.4cm),
  )
  set text(font: "Libertinus Serif", size: 10.5pt, fill: ink, lang: "en")
  set par(justify: true, leading: 0.65em, spacing: 1.15em)
  set heading(numbering: "1.1.")
  show heading: set block(above: 1.5em, below: 1.0em)
  show heading.where(level: 1): it => {
    text(size: 16pt, fill: accent, weight: "bold")[#it]
    v(-0.6em)
    line(length: 100%, stroke: 0.8pt + accent)
    v(0.3em)
  }
  show heading.where(level: 2): it => {
    text(size: 13pt, weight: "bold")[#it]
    v(-0.55em)
    line(length: 100%, stroke: 0.4pt + rule)
    v(0.25em)
  }
  show heading.where(level: 3): it => text(size: 11.5pt, weight: "bold")[#it]
  show heading: it => {
    if it.level >= 4 { text(size: 10.5pt, weight: "bold", style: "italic")[#it] } else { it }
  }

  // Running header from page 2; footer everywhere with classification.
  set page(header: context {
    if counter(page).get().first() > 1 [
      #set text(size: 8.5pt, fill: luma(95))
      #grid(
        columns: (1fr, auto),
        align: (left + horizon, right + horizon),
        text(style: "italic")[#title],
        if classification != "" [#classification],
      )
      #v(-0.55em)
      #line(length: 100%, stroke: 0.4pt + rule)
    ]
  })
  set page(footer: context {
    set text(size: 8.5pt, fill: luma(95))
    grid(
      columns: (1fr, auto, 1fr),
      align: (left + horizon, center + horizon, right + horizon),
      if date != "" [#date],
      counter(page).display("1 / 1", both: true),
      if classification != "" [#classification],
    )
  })

  // Title page.
  align(center + horizon)[
    #v(1fr)
    #block(width: 76%)[
      #if classification != "" [
        #text(size: 10pt, fill: accent, tracking: 2.5pt, weight: "semibold")[#upper(classification)]
        #v(1.4em)
      ]
      #text(size: 26pt, weight: "bold", fill: ink)[#title]
      #if subtitle != "" [#v(0.6em) #text(size: 14pt, fill: luma(80))[#subtitle]]
      #v(1.3em)
      #line(length: 30%, stroke: 1.2pt + accent)
      #v(1.3em)
      #text(size: 11pt, fill: luma(60))[
        #if author != "" [#author]
        #if author != "" and date != "" [#h(1.6em)]
        #if date != "" [#date]
      ]
    ]
    #v(1fr)
  ]
  pagebreak()

  // TOC when there is structure to show.
  context {
    let heads = query(heading)
    if heads.len() >= 2 [
      #outline(title: [Table of Contents], depth: 2)
      #pagebreak()
    ]
  }

  doc
}