// DEFAULT STUDENT TEMPLATE (framework default; ADR-0011).
//
// This is a *real, editable* file that lives in an engineering file at
// `exports/student.typ`. The framework compiles it AS THE MAIN FILE with the
// manifest injected:
//   typst compile --root <eng-root> --input manifest=<path-rel-to-root> exports/student.typ <out>
//
// It is intentionally self-contained (no shared helper import) so it can be
// copied verbatim into a new engineering file's `exports/`. Presentation —
// heading numbering — lives HERE (editable per engineering file), not in the
// manifest and not hardcoded in the cph-render package.
//
// WHY THE INCLUDE LOOP IS HERE AND NOT IN cph-render: typst resolves a dynamic
// `include` path relative to the file it lexically appears in, and a package has
// its own virtual root — an include inside cph-render would resolve against the
// PACKAGE, not the engineering root. A `/<part.path>/<field>.typ` written HERE
// (this template lives under `--root`) resolves against `--root`. So the
// template loads content and hands cph-render an already-assembled `parts` array.
//
// OPEN CONTRACT POINT — optional-content presence. typst has no "does this file
// exist" primitive (a missing `include` is a hard compile error). So the
// template CANNOT probe disk the way the old Rust driver did for lemma `proof`.
// It relies on the manifest declaring which optional content fields are present,
// via a per-part `fields` array listing the content fields that exist on disk
// (the engine knows this — it walks the part dir). Required fields are loaded
// unconditionally; optional fields load only if listed in `fields`. If a part
// omits `fields`, optional content is skipped (conservative). The exact shape of
// this declaration is for the manifest/Rust contract to pin.

#import "@local/cph-render:0.1.0": render-lesson, part-fields, default-heading-numbering

// This template IS the student build, so the target is fixed.
#let target = "student"

// Read the injected manifest (a path string relative to typst --root).
#let manifest = toml(sys.inputs.manifest)
#let info = manifest.at("info", default: (:))
#let raw-parts = manifest.at("parts", default: ())

// Assemble each part: include its content fields (computed absolute paths,
// resolved against --root) and read scalar fields from <path>/element.toml.
// `part-fields` (from cph-render) is the single source of truth for kind->fields.
#let parts = raw-parts.map(raw => {
  let kind = raw.at("kind", default: none)
  let path = raw.at("path", default: none)
  let spec = part-fields.at(kind, default: (content: (), optional-content: (), scalars: ()))
  // Which optional content fields are present on disk (manifest-declared).
  let present = raw.at("fields", default: ())
  let part = (kind: kind)

  // Required content fields: <path>/<field>.typ (absolute, root-relative).
  for field in spec.content {
    part.insert(field, include "/" + path + "/" + field + ".typ")
  }
  // Optional content fields: only when the manifest says the file exists.
  for field in spec.optional-content {
    if field in present {
      part.insert(field, include "/" + path + "/" + field + ".typ")
    }
  }
  // Scalar fields come from <path>/element.toml.
  if spec.scalars.len() > 0 {
    let element = toml("/" + path + "/element.toml")
    for field in spec.scalars {
      let v = element.at(field, default: none)
      if v != none and v != "" { part.insert(field, v) }
    }
  }
  part
})

// Presentation: per-level heading numbering. Default (一、 / 1.1 / 1.1.1) comes
// from cph-render; override here per engineering file if desired.
#render-lesson(
  info: info,
  target: target,
  parts: parts,
  heading-numbering: default-heading-numbering,
)