// cph-render — curriculum lesson render package.
//
// PUBLIC ENTRY: `render-lesson(info, target, outline, heading-numbering)`.
//
// MODEL (ADR-0011, outline shape per ADR-0029). A build compiles a *template
// file* (e.g. `exports/student.typ`) as the typst main, with the manifest
// injected via `--input manifest=<path>`. The template reads the manifest,
// loads each **element** entry's content, and calls `render-lesson` here.
// Presentation (heading numbering) lives in the template, not the manifest,
// not hardcoded-unreachable in this package — we only provide the DEFAULT
// scheme (`default-heading-numbering`) for the template to use or override.
//
// WHY THE TEMPLATE LOADS CONTENT, NOT US (the include-resolution finding):
//   typst resolves an `include`/`import` path relative to THE PACKAGE/FILE THE
//   include LEXICALLY APPEARS IN, and a package (`@local/cph-render`) has its OWN
//   virtual root. A dynamic `include` written inside this file resolves against
//   the PACKAGE root — even an absolute `/segments/x.typ` lands in the package
//   dir, NOT the engineering-file root (`--root`). Verified empirically.
//   Therefore the dynamic-include LOOP must live in the TEMPLATE (which lives at
//   `<root>/exports/*.typ`, so `/<part.path>/<field>.typ` resolves against
//   `--root`). `render-lesson` is content-in: it takes an ALREADY-ASSEMBLED
//   `outline` array of entry dicts and never includes anything itself.
//
// An `outline` entry the template hands us is one of:
//   - an ELEMENT: `entry-type: "element"`, `kind` plus that kind's
//     content/scalar fields. Content field VALUES are already-evaluated typst
//     content (the template produced them via `include`).
//   - a SECTION (ADR-0029): `entry-type: "section"`, `title` (heading text),
//     `depth` (1-based heading level). Contributes no element; it is a
//     heading at its depth-first-open position in the outline.
//
// kind -> fields (MVP) — see `part-fields` below, which the template uses to
// know what to load:
//   segment : textbook (content, required)
//   example : problem (content, required), solution (content, required),
//             source (string scalar, optional, from <path>/element.toml)
//   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 — template passes only the target string):
//   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

/// Per-kind field manifest, exported so a TEMPLATE knows exactly what to load
/// for each part without hardcoding the matrix. For each kind:
///   `content`: field names whose `<part.path>/<field>.typ` the template must
///              `include` (assembling them into the part dict).
///   `optional-content`: content fields that may be absent (template should
///              probe before including; absence is fine).
///   `scalars`: scalar field names the template reads from `<path>/element.toml`
///              (currently only example `source`).
/// Keeping this here (not in the template) keeps kind->fields a single source of
/// truth in the package; the template iterates it generically.
#let part-fields = (
  segment: (content: ("textbook",), optional-content: (), scalars: ()),
  example: (content: ("problem", "solution"), optional-content: (), scalars: ("source",)),
  lemma: (content: ("stmt",), optional-content: ("proof",), scalars: ()),
  sop: (content: ("sop",), optional-content: (), scalars: ()),
)

/// 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)]
      ],
    )
  }
}

/// Render one section-heading outline entry (ADR-0029): `entry.title` at
/// `entry.depth` (1-based heading level).
#let _render-section(entry) = {
  heading(level: entry.at("depth", default: 1))[#entry.at("title", default: "")]
}

/// Render one outline entry: an element dispatches on `kind` via
/// [`_render-part`]; a section (ADR-0029) renders its heading and contributes
/// no element.
#let _render-entry(entry, flags) = {
  if entry.at("entry-type", default: "element") == "section" {
    _render-section(entry)
  } else {
    _render-part(entry, flags)
  }
}

/// THE ENTRY POINT — called by a template (`exports/*.typ`).
///
/// - `info`:   dict, e.g. (title: "…", author: "…"). `author` may be absent.
///             Templates typically pass `manifest.at("info", default: (:))`.
/// - `target`: string. MVP: "student" | "teacher". Unknown => conservative.
///             Each template hardcodes its own target (student.typ => "student").
/// - `outline`: ordered array of outline-entry dicts (ADR-0029), ALREADY
///             ASSEMBLED by the template (element content fields included,
///             scalars read; section entries carry `title`/`depth`). See file
///             header for the entry shapes.
/// - `heading-numbering`: array of per-level numbly pattern strings, e.g.
///             `("{1:一}、", "{1:1}.{2:1}", "{1:1}.{2:1}.{3:1}")`. Presentation
///             lives in the template (ADR-0011); the template passes its chosen
///             scheme. Defaults to `default-heading-numbering` (the framework
///             default) when the template omits it.
#let render-lesson(
  info: (:),
  target: "student",
  outline: (),
  heading-numbering: default-heading-numbering,
) = {
  let title = info.at("title", default: [])
  let author = info.at("author", default: none)

  // `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 entry in outline {
    _render-entry(entry, flags)
  }
}

/// Shift a section entry's `depth` by `delta`; an element entry passes through
/// unchanged (elements carry no depth). Used by [`render-bundle`] to nest each
/// lesson's own outline one level under that lesson's title heading.
#let _shift-depth(entry, delta) = {
  if entry.at("entry-type", default: "element") == "section" {
    entry.depth = entry.depth + delta
  }
  entry
}

/// THE BUNDLE ENTRY POINT (ADR-0030) — called by a bundle target's template
/// (`exports/<target>.typ` under a `bundle.toml` root) to assemble several
/// already-loaded lessons into one combined document.
///
/// - `info`: the bundle's own `[info]` (title/author of the 合集).
/// - `lessons`: ordered array of `(info: .., target: .., outline: ..)` dicts —
///   one per `bundle.toml` `lessons` entry, each ALREADY ASSEMBLED exactly as
///   a single-lesson template would assemble it for [`render-lesson`].
/// - `heading-numbering`: shared per-level numbering scheme across the whole
///   bundle (ADR-0011 presentation-in-template stance; same knob as
///   `render-lesson`).
/// - `reset-counters`: whether `example`/`lemma` auto-counters reset at each
///   lesson boundary. **Default `true`** (ADR-0030's recommended default: a
///   lesson's internal "例题3" means that lesson's 例题3, so cross-lesson
///   continuation would silently break author references). Pass `false` for
///   a genuine "全书连续编号" 合集.
///
/// Each lesson's own outline is rendered under a depth-1 heading naming that
/// lesson (`lesson.info.title`); the lesson's own section headings shift one
/// level deeper (ADR-0029's per-lesson depths are relative to that lesson, so
/// nesting under the lesson-title heading keeps the outline↔structure
/// correspondence meaningful in the combined document). `@label`/`@ref`
/// cross-references stay global across the whole compiled document (typst's
/// ordinary behavior) regardless of `reset-counters`.
#let render-bundle(
  info: (:),
  lessons: (),
  heading-numbering: default-heading-numbering,
  reset-counters: true,
) = {
  let title = info.at("title", default: [])
  let author = info.at("author", default: none)

  set document(
    title: title,
    author: if author == none { () } else { author },
  )

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

  title-block()
  v(1.2em, weak: true)

  for lesson in lessons {
    if reset-counters {
      example-counter.update(0)
      lemma-counter.update(0)
    }

    let flags = _flags-for(lesson.at("target", default: "student"))
    let lesson-info = lesson.at("info", default: (:))

    heading(level: 1)[#lesson-info.at("title", default: [])]

    for entry in lesson.at("outline", default: ()) {
      _render-entry(_shift-depth(entry, 1), flags)
    }
  }
}

/// Render a teacher-facing outline. `children` is intentionally separate from
/// the lesson body: each node heading is accompanied by an optional planning
/// note rendered as a visually distinct teaching-tip box.
#let _render-outline-node(node, level) = {
  let title = node.at("title", default: "")
  let kind = node.at("kind", default: "")
  heading(level: level)[#title]

  if kind != "" {
    block(
      inset: (x: 0.35em, y: 0.1em),
      fill: gray.lighten(80%),
      radius: 0.2em,
      text(size: 9pt, fill: gray.darken(30%))[#kind],
    )
  }

  let notes = node.at("notes", default: none)
  if notes != none and notes != "" {
    block(
      width: 100%,
      inset: (x: 1em, y: 0.7em),
      fill: rgb("#fff8e7"),
      stroke: rgb("#e6c45a") + 0.6pt,
      radius: 0.3em,
      breakable: true,
      {
        set text(size: 10.5pt)
        text(weight: "bold")[教学提示]
        linebreak()
        notes
      },
    )
  }

  for child in node.at("children", default: ()) {
    _render-outline-node(child, level + 1)
  }
}

/// Render the outline document supplied by `cph outline --format pdf`.
#let render-outline(outline) = {
  let title = outline.at("title", default: "课程大纲")
  let authors = outline.at("authors", default: ())
  set document(title: title, author: authors)
  show: base-style.with(heading-numbering: default-heading-numbering)

  title-block()
  subtitle-block([课程大纲])
  for child in outline.at("children", default: ()) {
    _render-outline-node(child, 1)
  }
}