mig-bo4e 0.15.0

//! Static shape of the BO4E JSON the forward mapping emits for one PID.
//!
//! The forward mapping ([`MappingEngine::map_interchange`]) builds untyped JSON
//! from the mapping definitions. Code generators that emit typed views of that
//! JSON (the per-PID typed modules of `bo4e-edifact-types`) need to know every
//! shape it can take, not just what a validator requires. This module derives it
//! from the same definitions, code lookup and MIG the engine runs with, reusing
//! the engine's own path, enrichment and nesting rules:
//!
//! - each definition's `[fields]` targets become (dotted, nested) object fields;
//!   a `also_target` becomes a second field;
//! - a field is *enriched* when the engine would enrich it
//!   ([`CodeLookup::enrichment_codes`]); its values are the codes of the segment
//!   variant it reads ([`CodeLookup::field_codes`]) as written: the `enum_map`
//!   values, or the raw codes the `enum_map` does not cover;
//! - `[meta] parent_field` children become lists inside their parent object;
//! - definitions of the same entity merge (`deep_merge_insert`);
//! - an entity may be an array when any group on its source path (below the
//!   transaction root) repeats, or with `repeat_on_tag`;
//! - child entities may additionally appear inside their parent entity
//!   (`nest_child_entities_in_result`).
//!
//! [`MappingEngine::map_interchange`]: crate::MappingEngine::map_interchange

use std::collections::{BTreeMap, BTreeSet};

use mig_types::schema::mig::{MigSchema, MigSegmentGroup};

use crate::code_lists::CodeLists;
use crate::code_lookup::CodeLookup;
use crate::definition::{FieldMapping, MappingDefinition};
use crate::engine::{
    child_entity_nesting_pairs, is_nested_child_of, parse_tag_qualifier, strip_all_rep_indices,
    to_camel_case, MappingEngine, VariantCache,
};

/// Output shape of the message-level and transaction-level BO4E JSON of a PID.
#[derive(Debug, Clone, Default, PartialEq)]
pub struct OutputShape {
    /// `Nachricht.stammdaten` (message-level entities).
    pub message: ScopeShape,
    /// One transaction's `stammdaten`.
    pub transaction: ScopeShape,
}

/// Entities of one scope, keyed by their JSON key (camelCase entity name).
#[derive(Debug, Clone, Default, PartialEq)]
pub struct ScopeShape {
    pub entities: BTreeMap<String, EntityShape>,
}

/// One top-level entity of a scope.
#[derive(Debug, Clone, Default, PartialEq)]
pub struct EntityShape {
    /// Entity name (`[meta] entity`, PascalCase).
    pub entity: String,
    /// Union of the objects all definitions of this entity produce.
    pub object: ObjectShape,
    /// Whether the value may be an array of objects instead of one object.
    pub repeats: bool,
    /// JSON keys of child entities that may be nested inside this entity's
    /// objects (they may also stay at the top level of the scope).
    pub children: BTreeSet<String>,
    /// The field carrying the group's entry qualifier, when every definition of
    /// the entity's top group maps it (candidate for map-keying).
    pub key: Option<KeyField>,
}

/// A JSON object: field name → field shape.
#[derive(Debug, Clone, Default, PartialEq)]
pub struct ObjectShape {
    pub fields: BTreeMap<String, FieldShape>,
}

/// Shape of one object field.
#[derive(Debug, Clone, PartialEq)]
pub enum FieldShape {
    /// A string, or (enriched) a `{code, meaning, enum}` object.
    Leaf(LeafShape),
    /// A nested object (dotted targets).
    Object(ObjectShape),
    /// A `[meta] parent_field` list of objects.
    List {
        /// BO4E type of the elements (`[meta] bo4e_type` of the child definition).
        item_type: String,
        item: ObjectShape,
    },
    /// Different definitions write different kinds of value at this field.
    Mixed,
}

/// A string-valued field.
#[derive(Debug, Clone, Default, PartialEq)]
pub struct LeafShape {
    /// Values the engine can write, with the raw EDIFACT codes producing them.
    /// `None` when the value is free text or not enumerable.
    pub values: Option<BTreeMap<String, WrittenValue>>,
    /// Whether code enrichment can turn the value into a `{code, meaning, enum}`
    /// object (whose `code` is the written value).
    pub enriched: bool,
}

/// One value a code field can hold.
#[derive(Debug, Clone, Default, PartialEq)]
pub struct WrittenValue {
    /// Raw EDIFACT codes the engine writes as this value.
    pub raw_codes: BTreeSet<String>,
    /// Meaning of the (first) raw code, if known.
    pub meaning: String,
    /// Curated enum name of the (first) raw code, if known.
    pub enum_key: Option<String>,
}

/// The qualifier field of an entity whose group entry segment carries the
/// qualifier as a mapped field (e.g. NAD 3035 → `partnerrolle`).
#[derive(Debug, Clone, Default, PartialEq)]
pub struct KeyField {
    /// JSON field the qualifier is written to.
    pub field: String,
    /// Second field of a dual decomposition (`also_target`), if any.
    pub also_field: Option<String>,
    /// Raw code → (value written to `field`, value written to `also_field`).
    pub codes: BTreeMap<String, (String, Option<String>)>,
    /// Schema group node(s) of the entity (source paths of its top definitions).
    pub source_paths: BTreeSet<String>,
}

impl OutputShape {
    /// Shape of what `Mapper::from_edifact` emits for `pid` of this variant.
    ///
    /// With the PID `schema` JSON, whether a group repeats follows the PID's
    /// schema (AHB-narrowed `max_reps`); without it, the MIG.
    pub fn for_pid(vc: &VariantCache, pid: &str, schema: Option<&serde_json::Value>) -> Self {
        let key = format!("pid_{pid}");
        let tx_group = vc.tx_group(pid).unwrap_or("");
        let mig = vc.filtered_mig(pid);
        let lookup = vc.code_lookups.get(&key);
        let tx_defs = vc
            .transaction_defs
            .get(&key)
            .map(Vec::as_slice)
            .unwrap_or_default();
        let sources = Sources {
            lookup,
            mig: mig.as_ref(),
            schema,
            code_lists: Some(&vc.code_lists),
        };
        Self::from_parts(&vc.message_defs, tx_defs, tx_group, &sources)
    }

    /// Shape from the message engine's and the transaction engine's definitions.
    /// `tx_group` is the transaction group id (empty for message-only variants).
    pub fn from_parts(
        message_defs: &[MappingDefinition],
        transaction_defs: &[MappingDefinition],
        tx_group: &str,
        sources: &Sources<'_>,
    ) -> Self {
        let message = ScopeShape::build(message_defs, sources, None);
        let transaction = if tx_group.is_empty() {
            ScopeShape::default()
        } else {
            ScopeShape::build(transaction_defs, sources, Some(tx_group))
        };
        Self {
            message,
            transaction,
        }
    }
}

/// What the shape is derived from besides the definitions.
#[derive(Debug, Clone, Copy, Default)]
pub struct Sources<'a> {
    /// The PID's code lookup (decides code fields and their codes).
    pub lookup: Option<&'a CodeLookup>,
    /// The PID-filtered MIG (entry segments; repetition without a schema).
    pub mig: Option<&'a MigSchema>,
    /// The PID schema JSON (repetition).
    pub schema: Option<&'a serde_json::Value>,
    /// The shared tables a rule's `code_list` / `also_code_list` name. Without
    /// them a rule that names its table instead of spelling it inline looks
    /// untranslated, and its field seems to carry raw codes.
    pub code_lists: Option<&'a CodeLists>,
}

impl ScopeShape {
    fn build(defs: &[MappingDefinition], sources: &Sources<'_>, tx_group: Option<&str>) -> Self {
        let Sources {
            lookup,
            mig,
            code_lists,
            ..
        } = *sources;
        let mut entities: BTreeMap<String, EntityShape> = BTreeMap::new();
        for def in defs.iter().filter(|d| d.meta.parent_field.is_none()) {
            let key = to_camel_case(&def.meta.entity);
            let object = object_shape(def, defs, lookup, code_lists);
            let repeats = def_repeats(def, sources, tx_group);
            let entry = entities.entry(key).or_insert_with(|| EntityShape {
                entity: def.meta.entity.clone(),
                ..Default::default()
            });
            entry.object.merge(object);
            entry.repeats |= repeats;
        }

        for (_, parent, child, _) in child_entity_nesting_pairs(defs, tx_group) {
            let child_key = to_camel_case(&child);
            if !entities.contains_key(&child_key) {
                continue;
            }
            if let Some(p) = entities.get_mut(&to_camel_case(&parent)) {
                p.children.insert(child_key);
            }
        }

        for (key, entity) in entities.iter_mut() {
            entity.key = key_field(key, defs, lookup, mig, code_lists);
        }

        Self { entities }
    }
}

/// `werte` → `Werte`: the element type name of a list target.
fn to_pascal(name: &str) -> String {
    let mut chars = name.chars();
    match chars.next() {
        Some(first) => first.to_uppercase().chain(chars).collect(),
        None => String::new(),
    }
}

impl ObjectShape {
    /// Union with `other` (`deep_merge_insert` semantics: fields of both).
    pub fn merge(&mut self, other: ObjectShape) {
        for (name, field) in other.fields {
            match self.fields.remove(&name) {
                None => {
                    self.fields.insert(name, field);
                }
                Some(existing) => {
                    self.fields.insert(name, existing.merged(field));
                }
            }
        }
    }

    fn insert_path(&mut self, path: &str, leaf: LeafShape) {
        match path.split_once('.') {
            None => {
                let merged = match self.fields.remove(path) {
                    None => FieldShape::Leaf(leaf),
                    Some(existing) => existing.merged(FieldShape::Leaf(leaf)),
                };
                self.fields.insert(path.to_string(), merged);
            }
            // A list target (`werte[].code`): one element per matching
            // segment, each an object holding `rest`.
            Some((head, rest)) if head.ends_with("[]") => {
                let name = head.trim_end_matches("[]");
                let field =
                    self.fields
                        .entry(name.to_string())
                        .or_insert_with(|| FieldShape::List {
                            item_type: to_pascal(name),
                            item: ObjectShape::default(),
                        });
                match field {
                    FieldShape::List { item, .. } => item.insert_path(rest, leaf),
                    other => *other = FieldShape::Mixed,
                }
            }
            Some((head, rest)) => {
                let field = self
                    .fields
                    .entry(head.to_string())
                    .or_insert_with(|| FieldShape::Object(ObjectShape::default()));
                match field {
                    FieldShape::Object(obj) => obj.insert_path(rest, leaf),
                    other => *other = FieldShape::Mixed,
                }
            }
        }
    }
}

impl FieldShape {
    fn merged(self, other: FieldShape) -> FieldShape {
        match (self, other) {
            (FieldShape::Leaf(mut a), FieldShape::Leaf(b)) => {
                a.merge(b);
                FieldShape::Leaf(a)
            }
            (FieldShape::Object(mut a), FieldShape::Object(b)) => {
                a.merge(b);
                FieldShape::Object(a)
            }
            (
                FieldShape::List {
                    item_type,
                    item: mut a,
                },
                FieldShape::List { item: b, .. },
            ) => {
                a.merge(b);
                FieldShape::List { item_type, item: a }
            }
            _ => FieldShape::Mixed,
        }
    }
}

impl LeafShape {
    fn merge(&mut self, other: LeafShape) {
        self.enriched |= other.enriched;
        self.values = match (self.values.take(), other.values) {
            (Some(mut a), Some(b)) => {
                for (value, w) in b {
                    let entry = a.entry(value).or_default();
                    if entry.meaning.is_empty() {
                        entry.meaning = w.meaning;
                    }
                    if entry.enum_key.is_none() {
                        entry.enum_key = w.enum_key;
                    }
                    entry.raw_codes.extend(w.raw_codes);
                }
                Some(a)
            }
            _ => None,
        };
    }

    /// Whether the engine can write `value` here.
    pub fn may_be(&self, value: &str) -> bool {
        self.values.as_ref().map_or(true, |v| v.contains_key(value))
    }
}

/// `(element, component)` of a numeric field path like `nad.3.0`, as the engine
/// parses it.
fn path_position(path: &str) -> (String, Option<String>, (usize, usize)) {
    let parts: Vec<&str> = path.split('.').collect();
    let (tag, qualifier, _) = parse_tag_qualifier(parts[0]);
    let position = MappingEngine::parse_element_component(&parts[1..]);
    (tag, qualifier.map(String::from), position)
}

/// The object one definition produces (`extract_fields_from_instance`).
fn object_shape(
    def: &MappingDefinition,
    defs: &[MappingDefinition],
    lookup: Option<&CodeLookup>,
    code_lists: Option<&CodeLists>,
) -> ObjectShape {
    let mut obj = ObjectShape::default();
    for (path, mapping) in &def.fields {
        let (target, enum_map, also) = match mapping {
            FieldMapping::Simple(t) => (t.as_str(), None, None),
            FieldMapping::Structured(s) => (
                s.target.as_str(),
                table(code_lists, s.enum_map.as_ref(), s.code_list.as_deref()),
                s.also_target.as_deref().zip(table(
                    code_lists,
                    s.also_enum_map.as_ref(),
                    s.also_code_list.as_deref(),
                )),
            ),
            FieldMapping::Nested(_) => continue,
        };
        if target.is_empty() {
            continue;
        }
        let (tag, path_qualifier, (element, component)) = path_position(path);
        let (codes, enriched) = match (lookup, def.meta.source_path.as_deref()) {
            (Some(lookup), Some(sp)) => {
                let disc_qualifier = MappingEngine::discriminator_qualifier_for_tag(def, &tag);
                let (pq, dq) = (path_qualifier.as_deref(), disc_qualifier.as_deref());
                let enriched = lookup
                    .enrichment_codes(sp, &tag, pq, dq, element, component)
                    .is_some();
                // Codes of the segment variant the field reads (path qualifier or
                // same-tag discriminator); without one, of every variant.
                (
                    lookup.field_codes(sp, &tag, pq, dq, element, component),
                    enriched,
                )
            }
            _ => (None, false),
        };
        let values = codes.map(|codes| {
            let mut values: BTreeMap<String, WrittenValue> = BTreeMap::new();
            let raw = codes
                .iter()
                .map(|(code, e)| (code.clone(), e.meaning.clone(), e.enum_key.clone()))
                .chain(
                    enum_map
                        .into_iter()
                        .flatten()
                        .filter(|(code, _)| !codes.contains_key(*code))
                        .map(|(code, _)| (code.clone(), String::new(), None)),
                );
            for (code, meaning, enum_key) in raw {
                let written = enum_map
                    .and_then(|m| m.get(&code))
                    .cloned()
                    .unwrap_or_else(|| code.clone());
                let entry = values.entry(written).or_default();
                if entry.raw_codes.is_empty() {
                    entry.meaning = meaning;
                    entry.enum_key = enum_key;
                }
                entry.raw_codes.insert(code);
            }
            values
        });
        obj.insert_path(target, LeafShape { values, enriched });
        if let Some((also_target, also_map)) = also {
            let values = also_map
                .values()
                .map(|v| (v.clone(), WrittenValue::default()))
                .collect();
            obj.insert_path(
                also_target,
                LeafShape {
                    values: Some(values),
                    enriched: false,
                },
            );
        }
    }

    for child in defs.iter().filter(|c| is_nested_child_of(c, def)) {
        let field = child.meta.parent_field.clone().unwrap_or_default();
        let list = FieldShape::List {
            item_type: child.meta.bo4e_type.clone(),
            item: object_shape(child, defs, lookup, code_lists),
        };
        let merged = match obj.fields.remove(&field) {
            None => list,
            Some(existing) => existing.merged(list),
        };
        obj.fields.insert(field, merged);
    }
    obj
}

/// The table a rule translates through, as the engine resolves it
/// ([`CodeLists::resolve`]). Without the shared lists only an inline table counts.
fn table<'a>(
    code_lists: Option<&'a CodeLists>,
    inline: Option<&'a BTreeMap<String, String>>,
    named: Option<&str>,
) -> Option<&'a BTreeMap<String, String>> {
    match code_lists {
        Some(lists) => lists.resolve(inline, named),
        None => inline,
    }
}

/// The MIG group at `source_group` (rep indices stripped), with the groups on
/// the way there.
fn group_chain<'a>(mig: &'a MigSchema, source_group: &str) -> Option<Vec<&'a MigSegmentGroup>> {
    let mut chain = Vec::new();
    let mut groups = &mig.segment_groups;
    for part in strip_all_rep_indices(source_group).split('.') {
        let group = groups.iter().find(|g| g.id.eq_ignore_ascii_case(part))?;
        chain.push(group);
        groups = &group.nested_groups;
    }
    Some(chain)
}

/// Whether one definition can produce several objects for one scope instance.
fn def_repeats(def: &MappingDefinition, sources: &Sources<'_>, tx_group: Option<&str>) -> bool {
    if def.meta.source_group.is_empty() {
        return false;
    }
    if def.meta.repeat_on_tag.is_some() {
        return true;
    }
    let disc = MappingEngine::discriminator_qualifier(def);
    let mig_repeats = || {
        let Some(chain) = sources
            .mig
            .and_then(|m| group_chain(m, &def.meta.source_group))
        else {
            return true;
        };
        chain.iter().enumerate().any(|(i, g)| {
            let is_tx_root = i == 0 && tx_group.is_some_and(|tx| g.id.eq_ignore_ascii_case(tx));
            !is_tx_root && g.max_rep_std.max(g.max_rep_spec) > 1
        })
    };
    let (Some(schema), Some(sp)) = (sources.schema, def.meta.source_path.as_deref()) else {
        return mig_repeats();
    };
    match schema_path_repeats(schema, sp, tx_group, disc.as_deref()) {
        // A group the PID schema lacks is absent from the PID-filtered tree, so
        // the definition produces nothing.
        None => false,
        Some(true) => true,
        // A discriminator selects one AHB group variant, whose repetition the
        // schema states. Without one, the definition takes every repetition the
        // MIG allows (schema nodes can merge several AHB occurrences).
        Some(false) => disc.is_none() && mig_repeats(),
    }
}

/// Whether any PID schema group on `source_path` (below the transaction root)
/// allows more than one repetition. An unqualified part (`sg12`) stands for all
/// of its qualified variants (`sg12_z04`, ...). `None` if the path is not in
/// the schema.
fn schema_path_repeats(
    schema: &serde_json::Value,
    source_path: &str,
    tx_group: Option<&str>,
    discriminator: Option<&str>,
) -> Option<bool> {
    let mut level: Vec<&serde_json::Value> = vec![schema.get("fields")?];
    let mut repeats = false;
    let parts: Vec<&str> = source_path.split('.').collect();
    for (i, part) in parts.iter().copied().enumerate() {
        let mut next: Vec<&serde_json::Value> = map_names(&level, part)
            .into_iter()
            .map(|(_, node)| node)
            .collect();
        if next.is_empty() {
            return None;
        }
        // The last part of a discriminated definition only selects the variant
        // carrying its qualifier.
        if i == parts.len() - 1 && !part.contains('_') {
            if let Some(q) = discriminator.map(|q| format!("_{}", q.to_lowercase())) {
                let selected: Vec<&serde_json::Value> = map_names(&level, part)
                    .into_iter()
                    .filter(|(name, _)| name.to_lowercase().ends_with(&q))
                    .map(|(_, node)| node)
                    .collect();
                if !selected.is_empty() {
                    next = selected;
                }
            }
        }
        let is_tx_root = i == 0 && tx_group.is_some_and(|tx| part.eq_ignore_ascii_case(tx));
        if !is_tx_root {
            // Several variants of an unqualified group each contribute instances.
            repeats |= next.len() > 1;
            let last_discriminated = i == parts.len() - 1 && discriminator.is_some();
            repeats |= next.iter().any(|node| {
                node.get("max_reps")
                    .and_then(|v| v.as_u64())
                    .map_or(true, |max| max > 1)
                    // A node merging several AHB group occurrences lists their
                    // entry segments side by side; each is its own repetition.
                    || (!last_discriminated && entry_segment_count(node) > 1)
            });
        }
        level = next
            .iter()
            .filter_map(|node| node.get("children"))
            .collect();
    }
    Some(repeats)
}

/// Number of entry segments (segments with the first segment's id) a schema
/// group node lists.
fn entry_segment_count(node: &serde_json::Value) -> usize {
    let Some(segments) = node.get("segments").and_then(|v| v.as_array()) else {
        return 0;
    };
    let entry = segments.first().and_then(|s| s.get("id"));
    segments.iter().filter(|s| s.get("id") == entry).count()
}

/// Schema group nodes of `containers` matching a source path part: the node of
/// that name, or for an unqualified part (`sg12`) all its variants (`sg12_z04`).
fn map_names<'a>(
    containers: &[&'a serde_json::Value],
    part: &str,
) -> Vec<(&'a String, &'a serde_json::Value)> {
    let prefix = format!("{part}_");
    containers
        .iter()
        .filter_map(|c| c.as_object())
        .flatten()
        .filter(|(name, _)| {
            name.eq_ignore_ascii_case(part) || (!part.contains('_') && name.starts_with(&prefix))
        })
        .collect()
}

/// Qualifier field of `entity_key`: every definition at the entity's top group
/// maps the entry segment's qualifier (element 0, component 0) to the same field.
fn key_field(
    entity_key: &str,
    defs: &[MappingDefinition],
    lookup: Option<&CodeLookup>,
    mig: Option<&MigSchema>,
    code_lists: Option<&CodeLists>,
) -> Option<KeyField> {
    let mig = mig?;
    let entity_defs: Vec<&MappingDefinition> = defs
        .iter()
        .filter(|d| d.meta.parent_field.is_none() && to_camel_case(&d.meta.entity) == entity_key)
        .collect();
    let depth = |d: &MappingDefinition| d.meta.source_group.split('.').count();
    let top = entity_defs.iter().map(|d| depth(d)).min()?;
    let mut key: Option<KeyField> = None;
    for def in entity_defs.iter().filter(|d| depth(d) == top) {
        if def.meta.source_group.is_empty() || def.meta.discriminator.is_some() {
            return None;
        }
        let chain = group_chain(mig, &def.meta.source_group)?;
        let entry_tag = chain.last()?.segments.first()?.id.to_uppercase();
        let (field, enum_map, also) = def.fields.iter().find_map(|(path, mapping)| {
            let (tag, qualifier, position) = path_position(path);
            let numeric = path.split('.').skip(1).all(|p| p.parse::<usize>().is_ok());
            if tag != entry_tag || qualifier.is_some() || !numeric || position != (0, 0) {
                return None;
            }
            match mapping {
                FieldMapping::Simple(t) if !t.is_empty() => Some((t.clone(), None, None)),
                FieldMapping::Structured(s) if !s.target.is_empty() => Some((
                    s.target.clone(),
                    table(code_lists, s.enum_map.as_ref(), s.code_list.as_deref()),
                    s.also_target.clone().zip(table(
                        code_lists,
                        s.also_enum_map.as_ref(),
                        s.also_code_list.as_deref(),
                    )),
                )),
                _ => None,
            }
        })?;
        let also_field = also.as_ref().map(|(f, _)| f.clone());
        let entry = key.get_or_insert_with(|| KeyField {
            field: field.clone(),
            also_field: also_field.clone(),
            ..Default::default()
        });
        if entry.field != field || entry.also_field != also_field {
            return None;
        }
        let mut raw: BTreeSet<String> = enum_map
            .into_iter()
            .flatten()
            .map(|(c, _)| c.clone())
            .collect();
        if let (Some(lookup), Some(sp)) = (lookup, def.meta.source_path.as_deref()) {
            if let Some(codes) = lookup.codes_q(sp, &entry_tag, None, 0, 0) {
                raw.extend(codes.keys().cloned());
            }
            entry.source_paths.insert(sp.to_string());
        }
        for code in raw {
            let written = enum_map
                .and_then(|m| m.get(&code))
                .cloned()
                .unwrap_or_else(|| code.clone());
            let also_value = also.as_ref().and_then(|(_, m)| m.get(&code).cloned());
            let value = (written, also_value);
            match entry.codes.get(&code) {
                Some(existing) if *existing != value => return None,
                _ => {
                    entry.codes.insert(code, value);
                }
            }
        }
    }
    key.filter(|k| !k.codes.is_empty())
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    fn def(toml: &str) -> MappingDefinition {
        MappingDefinition::from_toml_str(toml).unwrap()
    }

    fn nad_node(code: &str, max_reps: u64) -> serde_json::Value {
        json!({
            "max_reps": max_reps,
            "discriminator": {"segment": "NAD", "element": "3035", "values": [code]},
            "segments": [{"id": "NAD", "elements": [
                {"index": 0, "id": "3035", "type": "code",
                 "codes": [{"value": code, "name": format!("Rolle {code}")}]}
            ]}]
        })
    }

    fn schema(sg12_max_reps: u64) -> serde_json::Value {
        json!({"fields": {
            "sg2": {"max_reps": 2, "segments": [], "children": {}},
            "sg4": {"max_reps": 99999, "segments": [], "children": {
                "sg5_z16": {"max_reps": 999999, "segments": []},
                "sg6": {"max_reps": 1, "segments": []},
                "sg12_z07": nad_node("Z07", sg12_max_reps),
                "sg12_z39": nad_node("Z39", sg12_max_reps),
                "sg12_z40": nad_node("Z40", sg12_max_reps),
            }}
        }})
    }

    fn mig() -> MigSchema {
        let segment = |id: &str| {
            json!({"id": id, "name": id, "description": null, "counter": null, "level": 1,
                   "number": null, "max_rep_std": 1, "max_rep_spec": 1, "status_std": null,
                   "status_spec": null, "example": null, "data_elements": [], "composites": []})
        };
        let group = |id: &str, entry: &str, nested: Vec<serde_json::Value>| {
            json!({"id": id, "name": id, "description": null, "counter": null, "level": 1,
                   "max_rep_std": 99, "max_rep_spec": 99, "status_std": null, "status_spec": null,
                   "segments": [segment(entry)], "nested_groups": nested})
        };
        serde_json::from_value(json!({
            "message_type": "UTILMD", "variant": null, "version": "", "publication_date": "",
            "author": "", "format_version": "FV2604", "source_file": "", "segments": [],
            "segment_groups": [group("SG4", "IDE", vec![
                group("SG12", "NAD", vec![group("SG13", "CTA", vec![])]),
            ])]
        }))
        .unwrap()
    }

    const GESCHAEFTSPARTNER: &str = r#"
[meta]
entity = "Geschaeftspartner"
bo4e_type = "Geschaeftspartner"
source_group = "SG4.SG12"
source_path = "sg4.sg12"

[fields]
"nad.3.0" = "name1"
"nad.0" = { target = "partnerrolle", enum_map = { "Z07" = "kundeMsb", "Z39" = "kundeLf", "Z40" = "kundeLf" }, also_target = "datenqualitaet", also_enum_map = { "Z39" = "base", "Z40" = "informative" } }
"#;

    const KONTAKTWEG: &str = r#"
[meta]
entity = "Geschaeftspartner"
bo4e_type = "Kontaktweg"
source_group = "SG4.SG12.SG13"
source_path = "sg4.sg12.sg13"
parent_field = "kontaktwege"

[fields]
"com.0.0" = "kontaktwert"
"#;

    fn shape(sg12_max_reps: u64) -> OutputShape {
        let schema = schema(sg12_max_reps);
        let lookup = CodeLookup::from_schema_value(&schema);
        let mig = mig();
        let defs = vec![def(GESCHAEFTSPARTNER), def(KONTAKTWEG)];
        OutputShape::from_parts(
            &[],
            &defs,
            "SG4",
            &Sources {
                lookup: Some(&lookup),
                mig: Some(&mig),
                schema: Some(&schema),
                code_lists: None,
            },
        )
    }

    #[test]
    fn code_field_values_are_written_values_with_raw_code_aliases() {
        let shape = shape(1);
        let gp = &shape.transaction.entities["geschaeftspartner"];
        let Some(FieldShape::Leaf(rolle)) = gp.object.fields.get("partnerrolle") else {
            panic!("partnerrolle leaf: {gp:#?}");
        };
        assert!(rolle.enriched, "a schema code field can be enriched");
        let values = rolle.values.as_ref().unwrap();
        let raw = |v: &str| values[v].raw_codes.iter().cloned().collect::<Vec<_>>();
        assert_eq!(values.keys().collect::<Vec<_>>(), ["kundeLf", "kundeMsb"]);
        assert_eq!(raw("kundeLf"), ["Z39", "Z40"]);
        assert_eq!(raw("kundeMsb"), ["Z07"]);
        assert_eq!(values["kundeMsb"].meaning, "Rolle Z07");

        let Some(FieldShape::Leaf(dq)) = gp.object.fields.get("datenqualitaet") else {
            panic!("datenqualitaet leaf");
        };
        assert!(!dq.enriched, "also_target values are never enriched");
        let dq_values: Vec<&String> = dq.values.as_ref().unwrap().keys().collect();
        assert_eq!(dq_values, ["base", "informative"]);

        assert!(
            matches!(gp.object.fields.get("name1"), Some(FieldShape::Leaf(l)) if l.values.is_none())
        );
        assert!(matches!(
            gp.object.fields.get("kontaktwege"),
            Some(FieldShape::List { item_type, item }) if item_type == "Kontaktweg"
                && item.fields.contains_key("kontaktwert")
        ));
    }

    #[test]
    fn key_field_records_joint_qualifier_decomposition() {
        let shape = shape(1);
        let key = shape.transaction.entities["geschaeftspartner"]
            .key
            .clone()
            .expect("key field");
        assert_eq!(key.field, "partnerrolle");
        assert_eq!(key.also_field.as_deref(), Some("datenqualitaet"));
        let codes: Vec<(&str, &str, Option<&str>)> = key
            .codes
            .iter()
            .map(|(c, (w, a))| (c.as_str(), w.as_str(), a.as_deref()))
            .collect();
        assert_eq!(
            codes,
            [
                ("Z07", "kundeMsb", None),
                ("Z39", "kundeLf", Some("base")),
                ("Z40", "kundeLf", Some("informative")),
            ]
        );
    }

    /// IFTSTA 21037 SG15: RFF+Z13 carries the PID as its only code, RFF+ACW and
    /// RFF+ACE a free reference; two CAV variants with different code lists.
    fn status_schema() -> serde_json::Value {
        let rff = |qual: &str, id: serde_json::Value| {
            json!({"id": "RFF", "elements": [{"index": 0, "composite": "C506", "components": [
                {"sub_index": 0, "id": "1153", "type": "code", "codes": [{"value": qual, "name": qual}]},
                id,
            ]}]})
        };
        let data = json!({"sub_index": 1, "id": "1154", "type": "data"});
        let cav = |qual: &str, codes: serde_json::Value| {
            json!({"id": "CAV", "elements": [{"index": 0, "composite": "C889", "components": [
                {"sub_index": 0, "id": "7111", "type": "code", "codes": [{"value": qual, "name": qual}]},
                {"sub_index": 1, "id": "7110", "type": "code", "codes": codes},
            ]}]})
        };
        json!({"fields": {"sg14": {"max_reps": 1, "segments": [], "children": {"sg15": {"max_reps": 1, "segments": [
            rff("Z13", json!({"sub_index": 1, "id": "1154", "type": "code",
                              "codes": [{"value": "21037", "name": "RD / NB-Bewertung"}]})),
            rff("ACW", data.clone()),
            rff("ACE", data),
            cav("Z91", json!([{"value": "A", "name": "Alpha"}, {"value": "B", "name": "Beta"}])),
            cav("ZF0", json!([{"value": "C", "name": "Gamma"}])),
        ]}}}}})
    }

    #[test]
    fn qualified_field_paths_take_codes_of_their_own_segment_variant() {
        let schema = status_schema();
        let lookup = CodeLookup::from_schema_value(&schema);
        let status = def(r#"
[meta]
entity = "Status"
bo4e_type = "Status"
source_group = "SG14.SG15"
source_path = "sg14.sg15"

[fields]
"rff[Z13].0.1" = "pruefidentifikator"
"rff[ACW].0.0" = "acwQualifier"
"rff[ACW].0.1" = "referenz"
"rff[ACE].0.1" = "gegenvorschlagReferenz"
"cav[Z91].0.1" = "z91Wert"
"cav.0.1" = "wert"
"#);
        let obj = object_shape(&status, &[], Some(&lookup), None);
        let leaf = |name: &str| match obj.fields.get(name) {
            Some(FieldShape::Leaf(l)) => l.clone(),
            other => panic!("{name}: {other:?}"),
        };
        let values = |name: &str| {
            leaf(name)
                .values
                .map(|v| v.keys().cloned().collect::<Vec<_>>())
        };
        for free_reference in ["referenz", "gegenvorschlagReferenz"] {
            assert_eq!(
                values(free_reference),
                None,
                "{free_reference} is RFF+ACW/ACE data, not RFF+Z13's PID code"
            );
            assert!(!leaf(free_reference).enriched);
        }
        assert_eq!(
            values("pruefidentifikator"),
            Some(vec!["21037".to_string()])
        );
        assert_eq!(values("acwQualifier"), Some(vec!["ACW".to_string()]));
        assert_eq!(
            values("z91Wert"),
            Some(vec!["A".to_string(), "B".to_string()])
        );
        assert_eq!(
            values("wert"),
            Some(vec!["A".to_string(), "B".to_string(), "C".to_string()]),
            "an unqualified path reads any CAV variant"
        );
    }

    /// A rule naming a shared code list (#165) emits the same names as one
    /// spelling the table inline, so its shape must be the same too. It was
    /// not: only the inline `enum_map` was read, and FV2504 — which names its
    /// lists almost everywhere — got typed variants for raw codes the engine
    /// never writes (#170: `partnerrolle` "kundeDesLf" unknown).
    #[test]
    fn a_named_code_list_shapes_like_the_inline_table() {
        let schema = status_schema();
        let lookup = CodeLookup::from_schema_value(&schema);
        let rule = |mapping: &str| {
            def(&format!(
                r#"
[meta]
entity = "Status"
bo4e_type = "Status"
source_group = "SG14.SG15"
source_path = "sg14.sg15"

[fields]
"cav[Z91].0.1" = {mapping}
"#
            ))
        };
        let inline = rule(r#"{ target = "z91Wert", enum_map = { "A" = "alpha", "B" = "beta" } }"#);
        let named = rule(r#"{ target = "z91Wert", code_list = "z91" }"#);
        let lists = crate::code_lists::CodeLists::from_toml_str(
            "[z91]\n\"A\" = \"alpha\"\n\"B\" = \"beta\"\n",
        )
        .unwrap();

        let values = |obj: &ObjectShape| match obj.fields.get("z91Wert") {
            Some(FieldShape::Leaf(l)) => l
                .values
                .as_ref()
                .map(|v| v.keys().cloned().collect::<Vec<_>>()),
            other => panic!("{other:?}"),
        };
        let expected = values(&object_shape(&inline, &[], Some(&lookup), None));
        assert_eq!(
            expected,
            Some(vec!["alpha".to_string(), "beta".to_string()])
        );
        assert_eq!(
            values(&object_shape(&named, &[], Some(&lookup), Some(&lists))),
            expected
        );
    }

    #[test]
    fn several_variants_of_an_unqualified_group_repeat() {
        assert!(shape(1).transaction.entities["geschaeftspartner"].repeats);
    }

    #[test]
    fn repetition_follows_the_pid_schema() {
        let schema = schema(1);
        let mig = mig();
        let sources = Sources {
            schema: Some(&schema),
            mig: Some(&mig),
            lookup: None,
            code_lists: None,
        };
        let repeats = |toml: &str, tx: Option<&str>| def_repeats(&def(toml), &sources, tx);
        let entity = |sg: &str, sp: &str, extra: &str| {
            format!(
                "[meta]\nentity = \"E\"\nbo4e_type = \"E\"\nsource_group = \"{sg}\"\n\
                 source_path = \"{sp}\"\n{extra}\n[fields]\n\"x.0\" = \"x\"\n"
            )
        };
        assert!(repeats(&entity("SG4.SG5", "sg4.sg5_z16", ""), Some("SG4")));
        assert!(
            !repeats(
                &entity("SG4.SG6", "sg4.sg6", "discriminator = \"RFF.0.0=Z13\""),
                Some("SG4")
            ),
            "a discriminated variant repeats as the schema says"
        );
        assert!(
            repeats(&entity("SG4.SG6", "sg4.sg6", ""), Some("SG4")),
            "without a discriminator the MIG's repetition counts (unknown here)"
        );
        assert!(!repeats(&entity("SG4", "sg4", ""), Some("SG4")), "tx root");
        assert!(repeats(&entity("SG2", "sg2", ""), None));
        assert!(
            !repeats(
                &entity("SG4.SG12", "sg4.sg12", "discriminator = \"NAD.0.0=Z07\""),
                Some("SG4")
            ),
            "a discriminator selects one variant"
        );
        assert!(
            !repeats(&entity("SG4.SG9", "sg4.sg9", ""), Some("SG4")),
            "absent group"
        );
        assert!(repeats(
            &entity("SG4.SG6", "sg4.sg6", "repeat_on_tag = \"FTX\""),
            Some("SG4")
        ));
    }
}