// cph-render — curriculum lesson render package.
//
// Single public entry: `display(info, target, parts)`.
//
// A lesson is an ORDERED array of typed parts. Each part is a dict with a
// `kind` plus that kind's content/scalar fields. Content field VALUES are
// already-evaluated typst content (the driver produces them via `include`) —
// never modules or strings; we render them directly.
//
// kind -> fields (MVP):
//   segment : textbook (content, required)
//   example : problem (content, required), solution (content, required),
//             source (string, optional)
//   lemma   : stmt (content, required), proof (content, optional)
//   sop     : sop (content, required)
//
// target -> show/hide (the (kind x target) render matrix; defaults per
// ADR-0005/0008, derived internally — caller passes no flags):
//   student : example problem only (hide solution); lemma stmt only (hide
//             proof); segment textbook; sop shown.
//   teacher : everything shown.
//   unknown : rendered conservatively == student (show only required-public
//             fields). Never crashes. The "no render rule => warning"
//             diagnostic is the Rust side's job, not ours.

#import "src/style.typ": base-style, default-heading-numbering, title-block, subtitle-block
#import "src/elements/segment.typ": display-segment
#import "src/elements/example.typ": display-example
#import "src/elements/lemma.typ": display-lemma
#import "src/elements/sop.typ": display-sop
#import "src/elements/common.typ": example-counter, lemma-counter

/// Resolve a target string to the set of show/hide booleans.
/// Unknown targets fall back to the conservative (student-like) profile.
#let _flags-for(target) = {
  if target == "teacher" {
    (show-solution: true, show-proof: true, subtitle: [教师版讲义])
  } else if target == "student" {
    (show-solution: false, show-proof: false, subtitle: [学生版讲义])
  } else {
    // Unknown target: conservative — show only required-public fields.
    (show-solution: false, show-proof: false, subtitle: [讲义])
  }
}

/// Render one part according to its `kind`. Unknown kinds render an inline
/// note instead of crashing.
#let _render-part(part, flags) = {
  let kind = part.at("kind", default: none)
  if kind == "segment" {
    display-segment(part)
  } else if kind == "example" {
    display-example(part, show-solution: flags.show-solution)
  } else if kind == "lemma" {
    display-lemma(part, show-proof: flags.show-proof)
  } else if kind == "sop" {
    display-sop(part)
  } else {
    // Don't crash on an unrecognised kind; surface it visibly instead.
    block(
      width: 100%,
      inset: 0.6em,
      fill: red.lighten(85%),
      stroke: red.darken(20%) + 0.6pt,
      radius: 0.4em,
      text(fill: red.darken(30%), weight: "bold")[
        [未知部件类型 / unknown kind: #repr(kind)]
      ],
    )
  }
}

/// THE ENTRY POINT.
///
/// - `info`:   dict, e.g. (title: "…", author: "…"). `author` may be absent.
/// - `target`: string. MVP: "student" | "teacher". Unknown => conservative.
/// - `parts`:  ordered array of part dicts (see file header).
/// - `config`: dict carrying the target's build/presentation overrides
///             (ADR-0009). Open/forward-compatible — read keys with
///             `.at(.., default: ..)`. Recognised keys (MVP):
///               `config.numbering.heading`: array of per-level numbly pattern
///                 strings, e.g. `("{1:一}、", "{1:1}.{2:1}")`. Optional; when
///                 absent the framework default (correct per-level scheme) is
///                 used. Future presentation knobs slot in without touching
///                 this signature.
#let display(info: (:), target: "student", parts: (), config: (:)) = {
  let title = info.at("title", default: [])
  let author = info.at("author", default: none)

  // Resolve presentation config -> framework defaults, file may override.
  // `config.numbering.heading` (array of numbly patterns) overrides the
  // framework default per-level numbering when present.
  let numbering-cfg = config.at("numbering", default: (:))
  let heading-numbering = numbering-cfg.at(
    "heading",
    default: default-heading-numbering,
  )

  // `document` author wants a string/array; normalise the optional field.
  set document(
    title: title,
    author: if author == none { () } else { author },
  )

  show: base-style.with(heading-numbering: heading-numbering)

  // Reset shared counters so each rendered lesson numbers from 1.
  example-counter.update(0)
  lemma-counter.update(0)

  let flags = _flags-for(target)

  title-block()
  subtitle-block(flags.subtitle)

  // Render strictly in array order.
  for part in parts {
    _render-part(part, flags)
  }
}