kyyn-core 0.1.13

//! The registry vocabulary — the *courtesy* artifact a KB's schema crate emits
//! (RON-native, committed to the KB) describing its kinds so the engine can
//! drive query/web/MCP UX generically. Integrity never depends on it: the
//! validation fn is the only load-bearing export. Where a protocol demands
//! JSON (MCP tool inputs), the engine derives it from this at the boundary.

use serde::{Deserialize, Serialize};

use crate::query::{
    BindingSource, BoolExpr, EdgeDirection, FieldRef, QueryDecl, ScalarExpr, TypedLiteral,
};

/// Everything the engine may know about a KB's shapes.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Registry {
    /// Hash of the schema crate's source — accept checks freshness against it.
    pub schema_hash: String,
    pub kinds: Vec<Kind>,
    /// Schema-authored analytical queries. The schema constructs these through
    /// the typed builder; this committed representation is backend-neutral and
    /// can be rendered by the web UI without parsing Rust.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub queries: Vec<QueryDecl>,
    /// This KB's role vocabulary — flat, declared once, adoptable by any
    /// kind (a Field's `role` names one). Universal for THIS KB, invisible
    /// to every other: the KB's words, mapped onto engine affordances.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub roles: Vec<RoleDecl>,
}

impl Registry {
    pub fn role(&self, name: &str) -> Option<&RoleDecl> {
        self.roles.iter().find(|r| r.name == name)
    }

    /// The engine affordance a field's adopted role binds, if any.
    pub fn binds(&self, field: &Field) -> Option<Affordance> {
        field
            .role
            .as_deref()
            .and_then(|n| self.role(n))
            .map(|r| r.binds)
    }

    /// The field of `kind` bound to `affordance`, if any.
    pub fn affordance_field<'a>(&self, kind: &'a Kind, a: Affordance) -> Option<&'a Field> {
        kind.fields.iter().find(|f| self.binds(f) == Some(a))
    }

    /// STRICT role coherence — an incoherent mapping makes the registry
    /// meaningless, so these are hard errors wherever a registry is loaded
    /// or generated: every adopted role is declared; the field's shape fits
    /// the affordance (Title = str, Timeline = date, Badge = enum); a Badge
    /// role's shared variants match the adopting field's enum EXACTLY. A
    /// kind wanting different vocabulary declares its own enum field and
    /// simply doesn't adopt the role.
    pub fn coherence_errors(&self) -> Vec<String> {
        // Affordances are SCALAR record-level statements: Option peels (an
        // unset title is still the title field) but List must not — a
        // List<Str> is not a title, and every consumer reads one scalar.
        fn base(ty: &FieldType) -> &FieldType {
            match ty {
                FieldType::Option(i) => base(i),
                other => other,
            }
        }
        let mut errors = Vec::new();
        for (i, r) in self.roles.iter().enumerate() {
            if self.roles[..i].iter().any(|x| x.name == r.name) {
                errors.push(format!("role '{}' is declared twice", r.name));
            }
            if r.binds == Affordance::Badge && r.variants.is_empty() {
                errors.push(format!("badge role '{}' declares no variants", r.name));
            }
            if r.binds != Affordance::Badge && !r.variants.is_empty() {
                errors.push(format!(
                    "role '{}' binds {:?} but declares variants — only Badge roles carry them",
                    r.name, r.binds
                ));
            }
        }
        // Roles bind at RECORD level: only a kind's top-level fields may
        // adopt one. A nested adoption would be silently inert (no consumer
        // looks below the top level) — refuse it loudly instead.
        fn nested_roles(prefix: &str, ty: &FieldType, errors: &mut Vec<String>) {
            match ty {
                FieldType::Option(i) | FieldType::List(i) => nested_roles(prefix, i, errors),
                FieldType::Struct(fs) => {
                    for f in fs {
                        let at = format!("{prefix}.{}", f.name);
                        if let Some(role) = &f.role {
                            errors.push(format!(
                                "{at} adopts role '{role}' but roles bind only to a \
                                 kind's top-level fields — nested adoptions are inert"
                            ));
                        }
                        nested_roles(&at, &f.ty, errors);
                    }
                }
                FieldType::Enum(vs) => {
                    for v in vs {
                        for f in &v.fields {
                            let at = format!("{prefix}.{}.{}", v.name, f.name);
                            if let Some(role) = &f.role {
                                errors.push(format!(
                                    "{at} adopts role '{role}' but roles bind only to a \
                                     kind's top-level fields — nested adoptions are inert"
                                ));
                            }
                            nested_roles(&at, &f.ty, errors);
                        }
                    }
                }
                _ => {}
            }
        }
        for kind in &self.kinds {
            for f in &kind.fields {
                nested_roles(&format!("{}.{}", kind.name, f.name), &f.ty, &mut errors);
            }
        }
        for kind in &self.kinds {
            // Storage is confined to facts/: `receipts/` (engine-owned),
            // registry.ron, sources.ron and schema/ are not a kind's to
            // claim, and `..`/absolute prefixes would escape the ontology.
            if !kind.storage.starts_with("facts/") || kind.storage.contains("..") {
                errors.push(format!(
                    "kind '{}' storage '{}' must live under facts/ (no .., no absolute paths)",
                    kind.name, kind.storage
                ));
            }
            for f in &kind.fields {
                let Some(role_name) = f.role.as_deref() else {
                    continue;
                };
                let at = format!("{}.{}", kind.name, f.name);
                let Some(decl) = self.role(role_name) else {
                    errors.push(format!("{at} adopts undeclared role '{role_name}'"));
                    continue;
                };
                match (decl.binds, base(&f.ty)) {
                    (Affordance::Title, FieldType::Str) => {}
                    (Affordance::Timeline, FieldType::Date) => {}
                    (Affordance::Badge, FieldType::Enum(vs)) => {
                        let field_vs: std::collections::BTreeSet<&str> =
                            vs.iter().map(|v| v.name.as_str()).collect();
                        let role_vs: std::collections::BTreeSet<&str> =
                            decl.variants.iter().map(|v| v.name.as_str()).collect();
                        if field_vs != role_vs {
                            errors.push(format!(
                                "{at} adopts badge role '{role_name}' but its variants \
                                 [{}] differ from the role's [{}] — roles are strict; \
                                 use the shared enum or drop the role",
                                vs.iter()
                                    .map(|v| v.name.as_str())
                                    .collect::<Vec<_>>()
                                    .join(", "),
                                decl.variants
                                    .iter()
                                    .map(|v| v.name.as_str())
                                    .collect::<Vec<_>>()
                                    .join(", "),
                            ));
                        }
                    }
                    (binds, other) => errors.push(format!(
                        "{at} adopts role '{role_name}' (binds {binds:?}) but is {other:?}"
                    )),
                }
            }
        }
        errors.extend(self.query_errors());
        errors
    }

    /// Bind every emitted query back against this registry. Typed Rust catches
    /// mistakes at the authoring call site; this second gate protects the
    /// serialized artifact from drift or hand edits.
    pub fn query_errors(&self) -> Vec<String> {
        use std::collections::{BTreeMap, BTreeSet};

        fn base(ty: &FieldType) -> &FieldType {
            match ty {
                FieldType::Option(inner) | FieldType::List(inner) => base(inner),
                other => other,
            }
        }

        fn literal_fits(ty: &FieldType, lit: &TypedLiteral) -> bool {
            match (base(ty), lit) {
                (FieldType::Str | FieldType::Markdown, TypedLiteral::String(_))
                | (FieldType::Int, TypedLiteral::Int(_))
                | (FieldType::Decimal, TypedLiteral::Decimal(_))
                | (FieldType::Date, TypedLiteral::Date(_))
                | (FieldType::Bool, TypedLiteral::Bool(_)) => true,
                (FieldType::Enum(variants), TypedLiteral::Enum { variant, .. }) => {
                    variants.iter().any(|v| v.name == *variant)
                }
                _ => false,
            }
        }

        fn field_type<'a>(
            bindings: &BTreeMap<u32, &'a Kind>,
            field: &FieldRef,
        ) -> Option<&'a FieldType> {
            bindings
                .get(&field.binding)?
                .fields
                .iter()
                .find(|f| f.name == field.field)
                .map(|f| &f.ty)
        }

        fn check_scalar(
            bindings: &BTreeMap<u32, &Kind>,
            query: &str,
            expr: &ScalarExpr,
            errors: &mut Vec<String>,
        ) {
            match expr {
                ScalarExpr::Field(f) => {
                    if field_type(bindings, f).is_none() {
                        errors.push(format!(
                            "query '{query}' references missing field binding {}.{}",
                            f.binding, f.field
                        ));
                    }
                }
                ScalarExpr::Literal(_) => {}
                ScalarExpr::Aggregate { expr, .. } => {
                    if let Some(expr) = expr {
                        check_scalar(bindings, query, expr, errors);
                    }
                }
            }
        }

        fn check_bool(
            bindings: &BTreeMap<u32, &Kind>,
            query: &str,
            expr: &BoolExpr,
            errors: &mut Vec<String>,
        ) {
            match expr {
                BoolExpr::And(xs) | BoolExpr::Or(xs) => xs
                    .iter()
                    .for_each(|x| check_bool(bindings, query, x, errors)),
                BoolExpr::Not(x) => check_bool(bindings, query, x, errors),
                BoolExpr::Compare { left, right, .. } => {
                    check_scalar(bindings, query, left, errors);
                    check_scalar(bindings, query, right, errors);
                    let pair = match (left, right) {
                        (ScalarExpr::Field(f), ScalarExpr::Literal(l))
                        | (ScalarExpr::Literal(l), ScalarExpr::Field(f)) => Some((f, l)),
                        _ => None,
                    };
                    if let Some((field, literal)) = pair
                        && let Some(ty) = field_type(bindings, field)
                        && !literal_fits(ty, literal)
                    {
                        errors.push(format!(
                            "query '{query}' compares {}.{} ({ty:?}) with incompatible {literal:?}",
                            field.binding, field.field
                        ));
                    }
                }
            }
        }

        let mut errors = Vec::new();
        let mut names = BTreeSet::new();
        for query in &self.queries {
            if !names.insert(query.name.as_str()) {
                errors.push(format!("query '{}' is declared twice", query.name));
            }
            let mut bindings = BTreeMap::new();
            for binding in &query.bindings {
                let Some(kind) = self.kinds.iter().find(|k| k.name == binding.kind) else {
                    errors.push(format!(
                        "query '{}' binding {} names missing kind '{}'",
                        query.name, binding.id, binding.kind
                    ));
                    continue;
                };
                if bindings.insert(binding.id, kind).is_some() {
                    errors.push(format!(
                        "query '{}' declares binding {} twice",
                        query.name, binding.id
                    ));
                }
            }
            for binding in &query.bindings {
                let BindingSource::Follow {
                    from,
                    field,
                    direction,
                    ..
                } = &binding.source
                else {
                    continue;
                };
                let (field_kind, target_kind) = match direction {
                    EdgeDirection::Out => (bindings.get(from), bindings.get(&binding.id)),
                    EdgeDirection::In => (bindings.get(&binding.id), bindings.get(from)),
                };
                let (Some(field_kind), Some(target_kind)) = (field_kind, target_kind) else {
                    errors.push(format!(
                        "query '{}' binding {} follows missing binding {}",
                        query.name, binding.id, from
                    ));
                    continue;
                };
                let Some(decl) = field_kind.fields.iter().find(|f| f.name == *field) else {
                    errors.push(format!(
                        "query '{}' follows missing edge '{}.{}'",
                        query.name, field_kind.name, field
                    ));
                    continue;
                };
                let points_to = match base(&decl.ty) {
                    FieldType::Link { allowed } => allowed
                        .as_ref()
                        .is_none_or(|ks| ks.iter().any(|k| k == &target_kind.name)),
                    FieldType::Str => decl.refers_to.as_deref() == Some(target_kind.name.as_str()),
                    _ => false,
                };
                if !points_to {
                    errors.push(format!(
                        "query '{}' edge '{}.{}' does not point to '{}'",
                        query.name, field_kind.name, field, target_kind.name
                    ));
                }
            }
            if query.bindings.is_empty() {
                errors.push(format!("query '{}' has no root binding", query.name));
            }
            if query.columns.is_empty() {
                errors.push(format!("query '{}' has no output columns", query.name));
            }
            if let Some(filter) = &query.filter {
                check_bool(&bindings, &query.name, filter, &mut errors);
            }
            for expr in &query.group_by {
                check_scalar(&bindings, &query.name, expr, &mut errors);
            }
            let mut columns = BTreeSet::new();
            for column in &query.columns {
                if let Some(f) = &column.format
                    && (f.thousands || f.decimals.is_some())
                {
                    // Numeric display options need a numeric expression: an
                    // aggregate count/sum, or a numeric field.
                    let numeric = match &column.expr {
                        ScalarExpr::Aggregate { .. } => true,
                        ScalarExpr::Field(fr) => field_type(&bindings, fr)
                            .map(|ty| matches!(base(ty), FieldType::Int | FieldType::Decimal))
                            .unwrap_or(false),
                        ScalarExpr::Literal(l) => {
                            matches!(l, TypedLiteral::Int(_) | TypedLiteral::Decimal(_))
                        }
                    };
                    if !numeric {
                        errors.push(format!(
                            "query '{}' column '{}' uses numeric formatting \
                             (thousands/decimals) on a non-numeric expression",
                            query.name, column.name
                        ));
                    }
                }
                if !columns.insert(column.name.as_str()) {
                    errors.push(format!(
                        "query '{}' has duplicate output column '{}'",
                        query.name, column.name
                    ));
                }
                check_scalar(&bindings, &query.name, &column.expr, &mut errors);
                // SQL's classic gate, enforced at accept instead of at run
                // time: under GROUP BY, every non-aggregate output column
                // must BE one of the grouping expressions.
                if !query.group_by.is_empty()
                    && !matches!(column.expr, ScalarExpr::Aggregate { .. })
                    && !query.group_by.contains(&column.expr)
                {
                    errors.push(format!(
                        "query '{}' output column '{}' is neither aggregated \
                         nor in group_by",
                        query.name, column.name
                    ));
                }
            }
            if query.group_by.is_empty() {
                let aggs = query
                    .columns
                    .iter()
                    .filter(|c| matches!(c.expr, ScalarExpr::Aggregate { .. }))
                    .count();
                if aggs > 0 && aggs < query.columns.len() {
                    errors.push(format!(
                        "query '{}' mixes aggregate and plain columns without \
                         group_by",
                        query.name
                    ));
                }
            }
            for expr in &query.group_by {
                if matches!(expr, ScalarExpr::Aggregate { .. }) {
                    errors.push(format!(
                        "query '{}' groups by an aggregate — group_by takes \
                         field expressions",
                        query.name
                    ));
                }
            }
            for order in &query.order_by {
                check_scalar(&bindings, &query.name, &order.expr, &mut errors);
            }
        }
        errors
    }
}

/// One KB-level role: this KB's own vocabulary, declared once and adoptable
/// by any kind. STRICT: a Badge role carries the shared variant vocabulary
/// (with tones) and every adopting field must match it exactly — that
/// agreement is what makes cross-kind treatment (badges, views) coherent.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RoleDecl {
    pub name: String,
    /// Curation intent for the concept, written once for the whole KB.
    pub doc: String,
    /// The engine affordance this role maps onto.
    pub binds: Affordance,
    /// Badge roles: the shared variants, each with its tone.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub variants: Vec<Variant>,
}

/// The engine's closed affordance vocabulary — what generic UI can DO with
/// a field. Never contains a domain word (that is the KB's registry `roles`
/// job); grows one affordance at a time, each justified by an engine
/// behaviour that cannot exist without it.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum Affordance {
    /// Names the record — lists, links, briefs.
    Title,
    /// Places the record on the KB's timeline — the sort key, the recency
    /// signal. (The alias keeps registries written before the rename
    /// parseable; regeneration writes `Timeline`.)
    #[serde(alias = "Date")]
    Timeline,
    /// A closed enum rendered as a tone-coloured badge.
    Badge,
}

/// Valence of one badge variant — the engine's palette; the KB decides
/// which of its own words map onto which tone.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum Tone {
    Positive,
    Neutral,
    Attention,
    Negative,
}

/// One kind of record.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Kind {
    /// Singular kind name — also the `Link` kind (`person`, `meeting`, …).
    pub name: String,
    /// Kind-level doc: what this is AND the existence bar (curation intent).
    pub doc: String,
    /// Storage pattern relative to the KB root, placeholders in `{}`
    /// (e.g. `facts/people/{id}.ron`, `facts/checkins/{person}/{date}.ron`).
    pub storage: String,
    pub fields: Vec<Field>,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct Field {
    pub name: String,
    /// The field's doc comment — write discipline, semantics, examples.
    pub doc: String,
    pub ty: FieldType,
    /// Name of a KB-declared role this field adopts (Registry::roles).
    /// Strictly checked — see Registry::coherence_errors.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub role: Option<String>,
    /// For plain string fields that hold another kind's bare id (a
    /// check-in's `person` slug): the target kind. REFERENCE semantics —
    /// the graph builds an edge from it; schema-declared, engine-generic.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub refers_to: Option<String>,
}

/// The structural type of a field — what generic UI needs to render and
/// generic query needs to filter. Deliberately smaller than Rust's type
/// system: the validation fn owns full fidelity.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum FieldType {
    /// Plain string.
    Str,
    /// Signed integer (i64 on the wire).
    Int,
    /// EXACT decimal, carried as a string on the wire (`"1250000.00"`) —
    /// never a float. The type for money amounts, quantities, rates.
    Decimal,
    /// An external web link with a human title, rendered as an anchor.
    /// On the wire: `(title: "PMO Tracker", url: "https://…")`. Distinct
    /// from `Link`, which addresses records INSIDE the knowledge graph.
    Hyperlink,
    /// Prose rendered as the KB's markdown subset (inline `[[links]]`).
    Markdown,
    Date,
    Bool,
    /// Closed sum type. Unit-only enums are the degenerate case (every
    /// variant's `fields` empty); variants with payloads carry their fields,
    /// so generic UI can render a variant selector + that variant's fields.
    Enum(Vec<Variant>),
    /// A `Link`; `allowed: None` = any kind.
    Link {
        allowed: Option<Vec<String>>,
    },
    List(Box<FieldType>),
    Option(Box<FieldType>),
    /// Nested record (e.g. an action's dated log entries).
    Struct(Vec<Field>),
}

/// One variant of an `Enum` field (or of a Badge role's shared vocabulary,
/// where `tone` is meaningful).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct Variant {
    pub name: String,
    #[serde(default, skip_serializing_if = "String::is_empty")]
    pub doc: String,
    /// Payload fields; empty = unit variant.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub fields: Vec<Field>,
    /// Badge-role vocabularies only: the variant's valence.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub tone: Option<Tone>,
}