kdl_codegen/emit/

typescript.rs

//! TypeScript emitter — renders [`ir::Schema`] into TypeScript source text.
//!
//! Ported from club-unison's `codegen/typescript.rs`. Output format is kept
//! faithful so Phase 1 Step 6 can diff this against club-unison's generator
//! for regression detection.
//!
//! ## What it emits
//!
//! - A fixed import / type-alias header (`Timestamp`, `UUID`, `LanguageCode`).
//! - data dialect: every [`ir::TypeDef`] — `interface` for structs, string
//!   `enum` for enums.
//! - entity dialect: every [`ir::Record`] as an `interface` carrying an
//!   `id: string` member; every [`ir::Relation`] as an edge `interface`
//!   carrying `id` / `in` / `out: string` plus its edge properties.
//! - protocol dialect: for every [`ir::Channel`], per club-unison's
//!   `generate_channel`:
//!   - one `interface` per event payload, request payload and `returns` message,
//!   - a `<Channel>ChannelEventTypes` type map,
//!   - a `<Channel>ChannelRequestTypes` type map,
//!   - a `<Channel>ChannelMeta` `const` carrying channel metadata.
//!
//! ## Differences from club-unison (IR-driven port)
//!
//! - No inline `_inline_*` message skipping and no `service` legacy handling.
//! - Named type references emit the bare PascalCase identifier; the special
//!   `timestamp` / `uuid` / `language_code` aliases of club-unison are still
//!   honoured for compatibility with the fixed header.
//!
//! ## Tier 2 — description / constraints
//!
//! - A `description` on an `interface` / `enum` or a field becomes a
//!   `/** ... */` JSDoc comment.
//! - Field `constraints` are **not** emitted — TypeScript's type system
//!   cannot express them, and `@minimum` / `@pattern` JSDoc hacks are
//!   deliberately avoided.

use crate::Emitter;
use crate::ir;

use super::case::to_pascal_case;

/// The TypeScript code generation target.
#[derive(Debug, Default, Clone, Copy)]
pub struct TypeScriptEmitter;

impl TypeScriptEmitter {
    /// Create a new [`TypeScriptEmitter`].
    pub fn new() -> Self {
        Self
    }
}

impl Emitter for TypeScriptEmitter {
    fn emit(&self, schema: &ir::Schema) -> String {
        let mut code = String::new();
        code.push_str(HEADER);
        code.push('\n');

        // data dialect — standalone type definitions.
        for ty in &schema.types {
            match ty {
                ir::TypeDef::Struct {
                    name,
                    description,
                    fields,
                } => {
                    code.push_str(&render_interface(name, description.as_deref(), fields));
                }
                ir::TypeDef::Enum {
                    name,
                    description,
                    variants,
                } => {
                    code.push_str(&render_enum(name, description.as_deref(), variants));
                }
            }
            code.push_str("\n\n");
        }

        // entity dialect — records and relations. Interface names are
        // PascalCased so a camelCase relation name (`derivedFrom`) is idiomatic.
        for record in &schema.records {
            code.push_str(&render_interface(
                &to_pascal_case(&record.name),
                record.description.as_deref(),
                &record_members(record),
            ));
            code.push_str("\n\n");
        }
        for relation in &schema.relations {
            code.push_str(&render_interface(
                &to_pascal_case(&relation.name),
                relation.description.as_deref(),
                &relation_members(relation),
            ));
            code.push_str("\n\n");
        }

        // protocol dialect — channel interfaces + metadata.
        if let Some(protocol) = &schema.protocol {
            if let Some(namespace) = &protocol.namespace {
                code.push_str(&format!("// Namespace: {namespace}\n"));
                code.push_str(&format!("// Version: {}\n\n", protocol.version));
            }
            for channel in &protocol.channels {
                code.push_str(&render_channel(channel));
                code.push_str("\n\n");
            }
        }

        code
    }
}

/// Fixed header block, matching club-unison's `generate_imports`.
const HEADER: &str = "\
// Auto-generated TypeScript definitions
// DO NOT EDIT MANUALLY

export type Timestamp = string; // ISO-8601 format
export type UUID = string;
export type LanguageCode = string; // ISO 639-1 format
";

/// Render a `/** ... */` JSDoc block at the given indentation from an optional
/// description, including a trailing newline. A multi-line description is
/// rendered as a `*`-prefixed block; a single line stays on one line.
fn render_doc(description: Option<&str>, indent: &str) -> String {
    match description {
        None => String::new(),
        Some(text) => {
            let mut lines = text.lines();
            match (lines.next(), text.contains('\n')) {
                (Some(first), false) => format!("{indent}/** {first} */\n"),
                (Some(first), true) => {
                    let mut out = format!("{indent}/**\n{indent} * {first}\n");
                    for line in lines {
                        out.push_str(&format!("{indent} * {line}\n"));
                    }
                    out.push_str(&format!("{indent} */\n"));
                    out
                }
                (None, _) => String::new(),
            }
        }
    }
}

/// Render a plain `interface` from a name and field list.
fn render_interface(name: &str, description: Option<&str>, fields: &[ir::Field]) -> String {
    let doc = render_doc(description, "");
    let body: Vec<String> = fields.iter().map(render_field).collect();
    format!("{doc}export interface {name} {{\n{}\n}}", body.join("\n"))
}

/// Render a string-valued `enum`.
fn render_enum(name: &str, description: Option<&str>, variants: &[String]) -> String {
    let doc = render_doc(description, "");
    let body: Vec<String> = variants
        .iter()
        .map(|v| format!("  {} = '{}',", to_pascal_case(v), v))
        .collect();
    format!("{doc}export enum {name} {{\n{}\n}}", body.join("\n"))
}

/// Render a single interface field line, prefixed by its JSDoc when the field
/// carries a description.
fn render_field(field: &ir::Field) -> String {
    let optional = if field.required { "" } else { "?" };
    let doc = render_doc(field.description.as_deref(), "  ");
    format!(
        "{doc}  {}{}: {};",
        field.name,
        optional,
        ty_to_ts(&field.ty)
    )
}

/// The synthetic `id: string` field shared by records and relations.
fn id_member() -> ir::Field {
    ir::Field {
        name: "id".to_string(),
        ty: ir::Ty::Primitive(ir::Prim::String),
        required: true,
        flexible: false,
        default: None,
        description: None,
        constraints: ir::Constraints::default(),
    }
}

/// A record's interface members: a leading `id`, then its declared fields.
fn record_members(record: &ir::Record) -> Vec<ir::Field> {
    let mut members = Vec::with_capacity(record.fields.len() + 1);
    members.push(id_member());
    members.extend(record.fields.iter().cloned());
    members
}

/// A relation's edge-interface members: `id` / `in` / `out`, then its
/// declared edge-property fields.
fn relation_members(relation: &ir::Relation) -> Vec<ir::Field> {
    let endpoint = |name: &str| ir::Field {
        name: name.to_string(),
        ty: ir::Ty::Primitive(ir::Prim::String),
        required: true,
        flexible: false,
        default: None,
        description: None,
        constraints: ir::Constraints::default(),
    };
    let mut members = Vec::with_capacity(relation.fields.len() + 3);
    members.push(id_member());
    members.push(endpoint("in"));
    members.push(endpoint("out"));
    members.extend(relation.fields.iter().cloned());
    members
}

/// Map an [`ir::Ty`] to its TypeScript type expression.
fn ty_to_ts(ty: &ir::Ty) -> String {
    match ty {
        ir::Ty::Primitive(p) => prim_to_ts(*p).to_string(),
        ir::Ty::Array(inner) => format!("{}[]", ty_to_ts(inner)),
        ir::Ty::Named(name) => named_to_ts(name),
        // a link is stored as the target record's id — a string.
        ir::Ty::Link(_) => "string".to_string(),
        // a string literal type maps 1:1 to a TS literal type.
        ir::Ty::Literal(value) => format!("'{value}'"),
        // a union maps to a TS union; members that map to the same TS type
        // are de-duplicated (`link<X> | string` both become `string`).
        ir::Ty::Union(members) => {
            let mut parts: Vec<String> = Vec::new();
            for m in members {
                let t = ty_to_ts(m);
                if !parts.contains(&t) {
                    parts.push(t);
                }
            }
            parts.join(" | ")
        }
    }
}

/// Map an [`ir::Prim`] to its TypeScript type.
fn prim_to_ts(p: ir::Prim) -> &'static str {
    match p {
        ir::Prim::String => "string",
        ir::Prim::Int | ir::Prim::Float => "number",
        ir::Prim::Bool => "boolean",
        ir::Prim::Datetime => "Timestamp",
        ir::Prim::Json => "any",
    }
}

/// Resolve a named type reference, honouring club-unison's special aliases.
fn named_to_ts(name: &str) -> String {
    match name {
        "timestamp" => "Timestamp".to_string(),
        "uuid" => "UUID".to_string(),
        "language_code" => "LanguageCode".to_string(),
        _ => to_pascal_case(name),
    }
}

/// Render a payload `interface` with a leading JSDoc comment of the given kind.
fn render_payload_interface(kind: &str, name: &str, fields: &[ir::Field]) -> String {
    if fields.is_empty() {
        format!("/** {kind} \"{name}\" — empty payload */\nexport interface {name} {{}}")
    } else {
        let body: Vec<String> = fields.iter().map(render_field).collect();
        format!(
            "/** {kind} \"{name}\" */\nexport interface {name} {{\n{}\n}}",
            body.join("\n")
        )
    }
}

/// Render the full block for one channel: payload interfaces, the event /
/// request type maps, and the `ChannelMeta` const. Ported from
/// club-unison's `generate_channel`.
fn render_channel(channel: &ir::Channel) -> String {
    let mut code = String::new();

    let backend_str = match channel.backend {
        ir::ChannelBackend::Stream => "stream",
        ir::ChannelBackend::Datagram => "datagram",
    };

    // Section header.
    let channel_id_note = match channel.channel_id {
        Some(id) => format!(", channel_id={id}"),
        None => String::new(),
    };
    code.push_str(&format!(
        "// ════════════════════════════════════════════════\n\
         // Channel: {name} (backend={backend_str}{channel_id_note})\n\
         // ════════════════════════════════════════════════\n\n",
        name = channel.name,
    ));

    // Event interfaces.
    let mut event_names: Vec<String> = Vec::new();
    for evt in &channel.events {
        code.push_str(&render_payload_interface("Event", &evt.name, &evt.fields));
        code.push_str("\n\n");
        event_names.push(evt.name.clone());
    }

    // Request / response interfaces. Each entry is (request name, response name).
    let mut request_mappings: Vec<(String, String)> = Vec::new();
    for req in &channel.requests {
        code.push_str(&render_payload_interface("Request", &req.name, &req.fields));
        code.push_str("\n\n");

        let response_name = match &req.returns {
            Some(returns) => {
                code.push_str(&render_payload_interface(
                    "Response",
                    &returns.name,
                    &returns.fields,
                ));
                code.push_str("\n\n");
                returns.name.clone()
            }
            None => "void".to_string(),
        };
        request_mappings.push((req.name.clone(), response_name));
    }

    let pascal = to_pascal_case(&channel.name);

    // Event type map.
    let event_types_name = format!("{pascal}ChannelEventTypes");
    code.push_str(&format!(
        "/** Event name → 生成 interface の map for \"{}\" (= type-narrowing 用) */\n",
        channel.name
    ));
    if event_names.is_empty() {
        code.push_str(&format!(
            "export type {event_types_name} = Record<string, never>;\n\n"
        ));
    } else {
        code.push_str(&format!("export interface {event_types_name} {{\n"));
        for n in &event_names {
            code.push_str(&format!("  {n}: {n};\n"));
        }
        code.push_str("}\n\n");
    }

    // Request type map.
    let request_types_name = format!("{pascal}ChannelRequestTypes");
    code.push_str(&format!(
        "/** Request name → {{ request, response }} 生成 interface の map for \"{}\" */\n",
        channel.name
    ));
    if request_mappings.is_empty() {
        code.push_str(&format!(
            "export type {request_types_name} = Record<string, never>;\n\n"
        ));
    } else {
        code.push_str(&format!("export interface {request_types_name} {{\n"));
        for (req_name, resp_type) in &request_mappings {
            code.push_str(&format!(
                "  {req_name}: {{ request: {req_name}; response: {resp_type} }};\n"
            ));
        }
        code.push_str("}\n\n");
    }

    // Channel metadata const.
    let meta_name = format!("{pascal}ChannelMeta");
    code.push_str(&format!(
        "/** Channel metadata for \"{}\" (= Phase 2 runtime SDK 用 type-narrowing 入力) */\n",
        channel.name
    ));
    code.push_str(&format!("export const {meta_name} = {{\n"));
    code.push_str(&format!("  name: {:?} as const,\n", channel.name));
    code.push_str(&format!("  backend: {backend_str:?} as const,\n"));
    if let Some(cid) = channel.channel_id {
        code.push_str(&format!("  channelId: {cid} as const,\n"));
    }
    let from_str = match channel.from {
        ir::ChannelFrom::Client => "client",
        ir::ChannelFrom::Server => "server",
        ir::ChannelFrom::Either => "either",
    };
    code.push_str(&format!("  from: {from_str:?} as const,\n"));
    let lifetime_str = match channel.lifetime {
        ir::ChannelLifetime::Transient => "transient",
        ir::ChannelLifetime::Persistent => "persistent",
    };
    code.push_str(&format!("  lifetime: {lifetime_str:?} as const,\n"));

    // events list.
    if event_names.is_empty() {
        code.push_str("  events: [] as const,\n");
    } else {
        code.push_str("  events: [");
        for (i, n) in event_names.iter().enumerate() {
            if i > 0 {
                code.push_str(", ");
            }
            code.push_str(&format!("{n:?}"));
        }
        code.push_str("] as const,\n");
    }

    // requests mapping.
    if request_mappings.is_empty() {
        code.push_str("  requests: {} as const,\n");
    } else {
        code.push_str("  requests: {\n");
        for (req_name, resp_type) in &request_mappings {
            code.push_str(&format!(
                "    {req_name}: {{ request: {req_name:?} as const, response: {resp_type:?} as const }},\n"
            ));
        }
        code.push_str("  } as const,\n");
    }

    // Phantom type carrier.
    code.push_str(&format!(
        "  __types: undefined as unknown as {{ events: {event_types_name}; requests: {request_types_name} }},\n"
    ));
    code.push_str("} as const;\n");

    code
}

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

    fn field(name: &str, ty: ir::Ty, required: bool) -> ir::Field {
        ir::Field {
            name: name.to_string(),
            ty,
            required,
            flexible: false,
            default: None,
            description: None,
            constraints: ir::Constraints::default(),
        }
    }

    #[test]
    fn emits_header() {
        let out = TypeScriptEmitter::new().emit(&ir::Schema::default());
        assert!(out.contains("// DO NOT EDIT MANUALLY"));
        assert!(out.contains("export type Timestamp = string;"));
        assert!(out.contains("export type UUID = string;"));
    }

    #[test]
    fn emits_interface_with_optional_field() {
        let schema = ir::Schema {
            types: vec![ir::TypeDef::Struct {
                name: "User".to_string(),
                description: None,
                fields: vec![
                    field("name", ir::Ty::Primitive(ir::Prim::String), true),
                    field("nick", ir::Ty::Primitive(ir::Prim::String), false),
                ],
            }],
            protocol: None,
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("export interface User {"));
        assert!(out.contains("  name: string;"));
        assert!(out.contains("  nick?: string;"));
    }

    #[test]
    fn emits_enum() {
        let schema = ir::Schema {
            types: vec![ir::TypeDef::Enum {
                name: "Role".to_string(),
                description: None,
                variants: vec!["admin".to_string(), "guest_user".to_string()],
            }],
            protocol: None,
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("export enum Role {"));
        assert!(out.contains("  Admin = 'admin',"));
        assert!(out.contains("  GuestUser = 'guest_user',"));
    }

    #[test]
    fn maps_types() {
        let schema = ir::Schema {
            types: vec![ir::TypeDef::Struct {
                name: "T".to_string(),
                description: None,
                fields: vec![
                    field("n", ir::Ty::Primitive(ir::Prim::Int), true),
                    field("b", ir::Ty::Primitive(ir::Prim::Bool), true),
                    field("at", ir::Ty::Primitive(ir::Prim::Datetime), true),
                    field("blob", ir::Ty::Primitive(ir::Prim::Json), true),
                    field(
                        "tags",
                        ir::Ty::Array(Box::new(ir::Ty::Primitive(ir::Prim::String))),
                        true,
                    ),
                    field("owner", ir::Ty::Named("user_account".to_string()), true),
                ],
            }],
            protocol: None,
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("  n: number;"));
        assert!(out.contains("  b: boolean;"));
        assert!(out.contains("  at: Timestamp;"));
        assert!(out.contains("  blob: any;"));
        assert!(out.contains("  tags: string[];"));
        assert!(out.contains("  owner: UserAccount;"));
    }

    #[test]
    fn emits_channel_interfaces_and_meta() {
        let schema = ir::Schema {
            types: vec![],
            records: vec![],
            relations: vec![],
            protocol: Some(ir::Protocol {
                name: "ping-pong".to_string(),
                version: "2.0.0".to_string(),
                namespace: Some("demo".to_string()),
                description: None,
                channels: vec![ir::Channel {
                    name: "ping-pong".to_string(),
                    from: ir::ChannelFrom::Client,
                    lifetime: ir::ChannelLifetime::Persistent,
                    backend: ir::ChannelBackend::Stream,
                    channel_id: None,
                    requests: vec![ir::Request {
                        name: "Ping".to_string(),
                        fields: vec![field("seq", ir::Ty::Primitive(ir::Prim::Int), true)],
                        returns: Some(ir::Message {
                            name: "Pong".to_string(),
                            fields: vec![field("seq", ir::Ty::Primitive(ir::Prim::Int), true)],
                        }),
                    }],
                    events: vec![ir::Event {
                        name: "Tick".to_string(),
                        fields: vec![],
                    }],
                }],
            }),
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("// Namespace: demo"));
        assert!(out.contains("// Channel: ping-pong (backend=stream)"));
        assert!(out.contains("/** Request \"Ping\" */"));
        assert!(out.contains("export interface Ping {"));
        assert!(out.contains("/** Response \"Pong\" */"));
        assert!(out.contains("/** Event \"Tick\" — empty payload */"));
        assert!(out.contains("export interface Tick {}"));
        assert!(out.contains("export interface PingPongChannelEventTypes {"));
        assert!(out.contains("export interface PingPongChannelRequestTypes {"));
        assert!(out.contains("  Ping: { request: Ping; response: Pong };"));
        assert!(out.contains("export const PingPongChannelMeta = {"));
        assert!(out.contains("  name: \"ping-pong\" as const,"));
        assert!(out.contains("  backend: \"stream\" as const,"));
        assert!(out.contains("  from: \"client\" as const,"));
        assert!(out.contains("  lifetime: \"persistent\" as const,"));
        assert!(out.contains("  events: [\"Tick\"] as const,"));
    }

    #[test]
    fn datagram_channel_meta_carries_channel_id() {
        let schema = ir::Schema {
            types: vec![],
            records: vec![],
            relations: vec![],
            protocol: Some(ir::Protocol {
                name: "telemetry".to_string(),
                version: "1.0.0".to_string(),
                namespace: None,
                description: None,
                channels: vec![ir::Channel {
                    name: "metrics".to_string(),
                    from: ir::ChannelFrom::Server,
                    lifetime: ir::ChannelLifetime::Persistent,
                    backend: ir::ChannelBackend::Datagram,
                    channel_id: Some(7),
                    requests: vec![],
                    events: vec![ir::Event {
                        name: "Sample".to_string(),
                        fields: vec![field("v", ir::Ty::Primitive(ir::Prim::Float), true)],
                    }],
                }],
            }),
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("// Channel: metrics (backend=datagram, channel_id=7)"));
        assert!(out.contains("  channelId: 7 as const,"));
        assert!(out.contains("  requests: {} as const,"));
        assert!(out.contains("export type MetricsChannelRequestTypes = Record<string, never>;"));
    }

    // -------------------------------------------------------------------------
    // Tier 1 — record / relation / link / literal / union
    // -------------------------------------------------------------------------

    #[test]
    fn record_becomes_interface_with_id() {
        let schema = ir::Schema {
            records: vec![ir::Record {
                name: "Atlas".to_string(),
                description: None,
                id_strategy: ir::IdStrategy::Uuidv7,
                fields: vec![field("name", ir::Ty::Primitive(ir::Prim::String), true)],
            }],
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("export interface Atlas {"));
        assert!(out.contains("  id: string;"));
        assert!(out.contains("  name: string;"));
    }

    #[test]
    fn relation_interface_is_pascal_cased_with_in_out() {
        let schema = ir::Schema {
            relations: vec![ir::Relation {
                name: "derivedFrom".to_string(),
                description: None,
                from: "Memory".to_string(),
                to: "Memory".to_string(),
                unique: true,
                fields: vec![field("reason", ir::Ty::Primitive(ir::Prim::String), false)],
            }],
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("export interface DerivedFrom {"));
        assert!(out.contains("  id: string;"));
        assert!(out.contains("  in: string;"));
        assert!(out.contains("  out: string;"));
        assert!(out.contains("  reason?: string;"));
    }

    #[test]
    fn link_literal_and_union_map_to_ts_types() {
        let schema = ir::Schema {
            records: vec![ir::Record {
                name: "Doc".to_string(),
                description: None,
                id_strategy: ir::IdStrategy::Uuidv7,
                fields: vec![
                    field("parent", ir::Ty::Link("Doc".to_string()), false),
                    field(
                        "visibility",
                        ir::Ty::Union(vec![
                            ir::Ty::Literal("public".to_string()),
                            ir::Ty::Literal("private".to_string()),
                        ]),
                        true,
                    ),
                ],
            }],
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("  parent?: string;"), "link → string");
        assert!(
            out.contains("  visibility: 'public' | 'private';"),
            "literal union → TS union of literals"
        );
    }

    // -------------------------------------------------------------------------
    // Tier 2 — description -> JSDoc (constraints are not emitted)
    // -------------------------------------------------------------------------

    #[test]
    fn interface_and_field_descriptions_become_jsdoc() {
        let mut content = field("content", ir::Ty::Primitive(ir::Prim::String), true);
        content.description = Some("Memory content text".to_string());
        let schema = ir::Schema {
            types: vec![ir::TypeDef::Struct {
                name: "Memory".to_string(),
                description: Some("User memory".to_string()),
                fields: vec![content],
            }],
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("/** User memory */\n"), "interface JSDoc");
        assert!(
            out.contains("  /** Memory content text */\n"),
            "field JSDoc"
        );
    }

    #[test]
    fn enum_description_becomes_jsdoc() {
        let schema = ir::Schema {
            types: vec![ir::TypeDef::Enum {
                name: "Role".to_string(),
                description: Some("An access role".to_string()),
                variants: vec!["admin".to_string()],
            }],
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("/** An access role */\n"));
    }

    #[test]
    fn constraints_do_not_appear_in_typescript_output() {
        // TypeScript's type system cannot express min/max/pattern.
        let mut f = field("confidence", ir::Ty::Primitive(ir::Prim::Float), true);
        f.constraints = ir::Constraints {
            min: Some(0),
            max: Some(1),
            ..Default::default()
        };
        let schema = ir::Schema {
            types: vec![ir::TypeDef::Struct {
                name: "T".to_string(),
                description: None,
                fields: vec![f],
            }],
            ..Default::default()
        };
        let out = TypeScriptEmitter::new().emit(&schema);
        assert!(out.contains("  confidence: number;"));
        assert!(!out.contains("@minimum"), "no constraint metadata leaks");
    }
}