quillmark_core/

reader.rs

//! Schema-bound typed reader — the read twin of
//! [`TypedWriter`](crate::TypedWriter).
//!
//! The read surface's verbs split by read-vs-write, but the deeper fault line is
//! **interpret-vs-transport**. [`Document::get`](crate::Card::payload) is
//! *transport*: it returns the stored value verbatim, schema-free and
//! round-trippable — the disambiguation / debug read. Projecting a field to
//! markdown is *interpretation*: a schema-shaped question ("this field's
//! richtext, as markdown") that a schema-free `Document` cannot answer without
//! guessing which fields are even richtext. [`Card::field_markdown`] carries the
//! projection but has no schema to name the field set, so an unknown field name
//! reads back as absent rather than as the typo it is.
//!
//! [`Quill::view`](crate::Quill::view) binds the schema — where the authority
//! already lives, the writer's twin — so a single verb interprets by the field's
//! declared type:
//!
//! ```ignore
//! let v = quill.view(&doc);
//! v.get("subject")?;            // richtext → Some(Markdown(..))
//! v.get("qty")?;                // integer  → Some(Value(3))
//! v.get("absent")?;             // absent   → None
//! v.get("nope");                // unknown name → Err(UnknownField)
//! v.card(2)?.get("body")?;      // card field, kind resolves its schema
//! ```
//!
//! **absence returns; mismatch raises; an unknown name is a typo.** A `richtext`
//! field projects to markdown ([`ReadValue::Markdown`]) and a `plaintext` field
//! to its literal text ([`ReadValue::Plaintext`]); every other declared type
//! returns its canonical value verbatim ([`ReadValue::Value`]) — the same
//! transport `Document` reads, now reached with schema authority. A present value
//! that does not decode under a content field raises
//! [`EditError::FieldRichtextDecode`], the mismatch [`Card::field_markdown`] /
//! [`Card::field_plaintext`] surfaces. A name the schema does not declare raises
//! [`EditError::UnknownField`], exactly as [`TypedWriter::set`](crate::TypedWriter::set)
//! rejects it on the write side.
//!
//! The body read stays quill-free: a body's type is a format fact, not a schema
//! fact, so [`get_body`](TypedReader::get_body) mirrors
//! [`Card::body_markdown`](crate::Card::body_markdown) rather than consulting the
//! schema.
//!
//! Like [`TypedWriter`](crate::TypedWriter), a bound reader holds `&Document`
//! and `&QuillConfig`, so
//! it cannot cross a binding boundary that carries no lifetimes (wasm-bindgen /
//! pyo3); those surfaces construct one per call from the quill handle.

use indexmap::IndexMap;

use crate::document::{Card, Document, EditError, RichtextDecodeError};
use crate::quill::{CardSchema, FieldSchema, FieldType, QuillConfig};
use crate::value::QuillValue;

/// The interpreted value at a field address — the output of [`TypedReader::get`].
/// A content field decodes to its codec's projection (`richtext` to markdown,
/// `plaintext` to literal text); every other declared type carries its canonical
/// value verbatim (the transport read, reached through the schema). Absence is
/// the `None` of the enclosing `Option`, not a variant here.
#[derive(Debug, Clone, PartialEq)]
pub enum ReadValue {
    /// A `richtext` field projected to markdown (`export ∘ decode`) — the lossy,
    /// on-demand view (content-only marks do not survive markdown).
    Markdown(String),
    /// A `plaintext` field projected through its literal codec (`to_plaintext ∘
    /// decode`) — verbatim text, marks never interpreted (`*hi*` is four
    /// characters, not emphasis).
    Plaintext(String),
    /// A non-content field's canonical value, verbatim — the schema-free
    /// transport read a `Document` returns, delivered here with schema authority.
    Value(QuillValue),
}

impl ReadValue {
    /// The projected text of a content field — markdown for a `richtext` field,
    /// literal text for a `plaintext` field; `None` for a [`Value`](ReadValue::Value).
    pub fn as_text(&self) -> Option<&str> {
        match self {
            ReadValue::Markdown(s) | ReadValue::Plaintext(s) => Some(s),
            ReadValue::Value(_) => None,
        }
    }

    /// The canonical value, when this is a [`Value`](ReadValue::Value).
    pub fn as_value(&self) -> Option<&QuillValue> {
        match self {
            ReadValue::Value(v) => Some(v),
            ReadValue::Markdown(_) | ReadValue::Plaintext(_) => None,
        }
    }
}

/// A [`Document`] bound to its [`QuillConfig`] for typed reads. Construct with
/// [`Quill::view`](crate::Quill::view). Reads target the main card; use
/// [`card`](Self::card) for a composable card. The read twin of
/// [`TypedWriter`](crate::TypedWriter).
pub struct TypedReader<'a> {
    config: &'a QuillConfig,
    doc: &'a Document,
}

impl<'a> TypedReader<'a> {
    /// Bind `doc` to `config`. Prefer [`Quill::view`](crate::Quill::view).
    pub fn new(config: &'a QuillConfig, doc: &'a Document) -> Self {
        Self { config, doc }
    }

    /// Read a main-card field, interpreted by its declared type — `richtext` to
    /// markdown ([`ReadValue::Markdown`]), `plaintext` to literal text
    /// ([`ReadValue::Plaintext`]), every other type verbatim
    /// ([`ReadValue::Value`]). `Ok(None)` when the field is absent;
    /// [`EditError::UnknownField`] for a name the schema does not declare (a typo,
    /// as on the write side); [`EditError::FieldRichtextDecode`] when a content
    /// field holds a value that does not decode (a scalar an opaque
    /// [`store_field`](crate::Card::store_field) wrote).
    pub fn get(&self, name: &str) -> Result<Option<ReadValue>, EditError> {
        read_field(self.doc.main(), Some(&self.config.main.fields), name)
    }

    /// The main body's markdown projection — the quill-free body read
    /// ([`Card::body_markdown`](crate::Card::body_markdown)). A body's type is a
    /// format fact, not a schema fact, so this consults no schema and never
    /// raises; the body is never absent.
    pub fn get_body(&self) -> String {
        self.doc.main().body_markdown()
    }

    /// A schema-bound reader for the composable card at `index`. The card's
    /// `$kind` resolves its [`CardSchema`]; an unknown kind carries no schema, so
    /// every field name on it is undeclared and reads with
    /// [`EditError::UnknownField`] (read such a card verbatim through
    /// [`Card::payload`]). [`EditError::IndexOutOfRange`] when `index` is out of
    /// range — a boundary error, not an absent field, as the card write verbs
    /// treat it.
    pub fn card(&self, index: usize) -> Result<CardReader<'_>, EditError> {
        let len = self.doc.cards().len();
        let card = self
            .doc
            .card(index)
            .ok_or(EditError::IndexOutOfRange { index, len })?;
        let schema = card.kind().and_then(|k| self.config.card_kind(k));
        Ok(CardReader { schema, card })
    }
}

/// A single composable card bound to its [`CardSchema`], from
/// [`TypedReader::card`]. Same `get` / `get_body` verbs as [`TypedReader`],
/// reading the card at its bound index.
pub struct CardReader<'a> {
    schema: Option<&'a CardSchema>,
    card: &'a Card,
}

impl CardReader<'_> {
    /// The card's `$kind`, if any.
    pub fn kind(&self) -> Option<&str> {
        self.card.kind()
    }

    /// Read a field on this card, interpreted by its declared type — the card
    /// twin of [`TypedReader::get`]. Resolves the field against the card's
    /// [`CardSchema`]; a name the schema does not declare — or any name when the
    /// card kind is unknown — reads with [`EditError::UnknownField`].
    pub fn get(&self, name: &str) -> Result<Option<ReadValue>, EditError> {
        read_field(self.card, self.schema.map(|s| &s.fields), name)
    }

    /// This card's body markdown — the card twin of [`TypedReader::get_body`],
    /// quill-free and never raising.
    pub fn get_body(&self) -> String {
        self.card.body_markdown()
    }
}

/// The shared read dispatch behind [`TypedReader::get`] and [`CardReader::get`]:
/// resolve `name` against `fields_schema` (an unknown name, or every name when
/// the whole schema is `None` — an unknown card kind — is
/// [`EditError::UnknownField`]), then interpret by the field's declared type. A
/// content field projects through its codec — `richtext` via
/// [`Card::field_markdown`], `plaintext` via [`Card::field_plaintext`] — each
/// carrying the projection's absent (`None`) / mismatch
/// ([`EditError::FieldRichtextDecode`]) outcomes; every other type returns its
/// canonical value verbatim, `None` when absent.
fn read_field(
    card: &Card,
    fields_schema: Option<&IndexMap<String, FieldSchema>>,
    name: &str,
) -> Result<Option<ReadValue>, EditError> {
    let schema = fields_schema
        .and_then(|m| m.get(name))
        .ok_or_else(|| EditError::UnknownField(name.to_string()))?;
    match schema.r#type {
        FieldType::RichText { .. } => project(card.field_markdown(name), name, ReadValue::Markdown),
        FieldType::PlainText { .. } => {
            project(card.field_plaintext(name), name, ReadValue::Plaintext)
        }
        _ => Ok(card
            .payload()
            .get(name)
            .map(|v| ReadValue::Value(v.clone()))),
    }
}

/// Lift a codec projection ([`Card::field_markdown`] / [`Card::field_plaintext`])
/// into a [`ReadValue`]: `None` absent, `Some(Ok)` wrapped by `wrap`, `Some(Err)`
/// the [`EditError::FieldRichtextDecode`] mismatch naming `name`.
fn project(
    projection: Option<Result<String, RichtextDecodeError>>,
    name: &str,
    wrap: fn(String) -> ReadValue,
) -> Result<Option<ReadValue>, EditError> {
    match projection {
        None => Ok(None),
        Some(Ok(text)) => Ok(Some(wrap(text))),
        Some(Err(e)) => Err(EditError::FieldRichtextDecode {
            field: name.to_string(),
            message: e.into_message(),
        }),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::document::Document;
    use crate::version::QuillReference;
    use std::str::FromStr;

    const QUILL_YAML: &str = "\
quill:
  name: memo
  backend: typst
  version: 1.0.0
  description: Reader test quill
main:
  fields:
    subject:
      type: richtext
      inline: true
    note:
      type: plaintext
    qty:
      type: integer
card_kinds:
  note:
    fields:
      body:
        type: richtext
";

    fn config() -> QuillConfig {
        QuillConfig::from_yaml(QUILL_YAML).expect("valid quill")
    }

    fn blank_doc() -> Document {
        Document::new(QuillReference::from_str("memo@1.0.0").unwrap())
    }

    // Build a document through the writer, then read it back through the view.
    fn seeded_doc(config: &QuillConfig) -> Document {
        let mut doc = blank_doc();
        {
            let mut w = crate::TypedWriter::new(config, &mut doc);
            w.set("subject", "Hello **world**").unwrap();
            w.set("qty", "3").unwrap();
            w.add_card("note", [("body", "a *card*")], None, None).unwrap();
        }
        doc
    }

    #[test]
    fn richtext_field_projects_to_markdown() {
        let config = config();
        let doc = seeded_doc(&config);
        let view = TypedReader::new(&config, &doc);
        assert_eq!(
            view.get("subject").unwrap(),
            Some(ReadValue::Markdown("Hello **world**".to_string()))
        );
    }

    #[test]
    fn plaintext_field_projects_to_literal_text() {
        let config = config();
        let mut doc = blank_doc();
        {
            let mut w = crate::TypedWriter::new(&config, &mut doc);
            // Marks are literal under plaintext: `*hi*` is verbatim, not emphasis.
            w.set("note", "a *literal* line").unwrap();
        }
        let view = TypedReader::new(&config, &doc);
        assert_eq!(
            view.get("note").unwrap(),
            Some(ReadValue::Plaintext("a *literal* line".to_string()))
        );
    }

    #[test]
    fn scalar_field_returns_canonical_value() {
        let config = config();
        let doc = seeded_doc(&config);
        let view = TypedReader::new(&config, &doc);
        assert_eq!(
            view.get("qty").unwrap(),
            Some(ReadValue::Value(QuillValue::from_json(serde_json::json!(3))))
        );
    }

    #[test]
    fn absent_field_returns_none() {
        let config = config();
        let doc = blank_doc();
        let view = TypedReader::new(&config, &doc);
        assert_eq!(view.get("subject").unwrap(), None);
        assert_eq!(view.get("qty").unwrap(), None);
    }

    #[test]
    fn unknown_field_name_raises() {
        let config = config();
        let doc = blank_doc();
        let view = TypedReader::new(&config, &doc);
        assert!(matches!(
            view.get("nope"),
            Err(EditError::UnknownField(name)) if name == "nope"
        ));
    }

    #[test]
    fn richtext_field_holding_scalar_raises_mismatch() {
        let config = config();
        let mut doc = blank_doc();
        // An opaque write puts a bare number under the `subject` richtext field.
        doc.main_mut()
            .store_field("subject", QuillValue::from_json(serde_json::json!(3)))
            .unwrap();
        let view = TypedReader::new(&config, &doc);
        assert!(matches!(
            view.get("subject"),
            Err(EditError::FieldRichtextDecode { field, .. }) if field == "subject"
        ));
    }

    #[test]
    fn card_field_reads_through_kind_schema() {
        let config = config();
        let doc = seeded_doc(&config);
        let view = TypedReader::new(&config, &doc);
        let card = view.card(0).unwrap();
        assert_eq!(card.kind(), Some("note"));
        assert_eq!(
            card.get("body").unwrap(),
            Some(ReadValue::Markdown("a *card*".to_string()))
        );
        assert!(matches!(card.get("nope"), Err(EditError::UnknownField(_))));
    }

    #[test]
    fn card_out_of_range_raises() {
        let config = config();
        let doc = blank_doc();
        let view = TypedReader::new(&config, &doc);
        assert!(matches!(
            view.card(9),
            Err(EditError::IndexOutOfRange { index: 9, len: 0 })
        ));
    }

    #[test]
    fn body_read_is_quill_free() {
        let config = config();
        let mut doc = blank_doc();
        doc.main_mut().revise_body("A **body**.").unwrap();
        let view = TypedReader::new(&config, &doc);
        assert_eq!(view.get_body(), "A **body**.");
    }
}