alef 0.84.0

use super::{pyi_docstring, python_safe_name};
use crate::backends::pyo3::type_map::python_type;
use crate::core::ir::{EnumDef, EnumVariant, TypeRef};
use ahash::AHashSet;

/// Map a data-enum factory-constructor param type to its stub annotation, widening dataclass-backed
/// config DTOs. The bare name (`LlmConfig`) resolves to the compiled `#[pyclass]` this stub declares,
/// but the public name users pass is the `options.py` `@dataclass`, so such a param is widened to
/// `options.<Name> | dict[str, Any]` — the public wrapper or a dict, matching what the runtime
/// `__alef_coerce_dto` accepts. Non-DTO types (and the inner of containers) fall back to
/// [`python_type`], so the output is byte-identical to it wherever no coercible DTO is present.
fn factory_param_type(ty: &TypeRef, coercible_dtos: &AHashSet<&str>) -> String {
    match ty {
        TypeRef::Named(name) if coercible_dtos.contains(name.as_str()) => {
            format!("options.{name} | dict[str, Any]")
        }
        TypeRef::Optional(inner) => format!("{} | None", factory_param_type(inner, coercible_dtos)),
        TypeRef::Vec(inner) => format!("list[{}]", factory_param_type(inner, coercible_dtos)),
        TypeRef::Map(k, v) => format!(
            "dict[{}, {}]",
            factory_param_type(k, coercible_dtos),
            factory_param_type(v, coercible_dtos)
        ),
        _ => python_type(ty),
    }
}

fn to_python_enum_variant(name: &str) -> String {
    use heck::ToShoutySnakeCase;
    crate::core::keywords::python_str_enum_ident(&name.to_shouty_snake_case())
}

/// Generate a Python enum stub.
pub(super) fn gen_enum_stub(
    enum_def: &EnumDef,
    emit_docstrings: bool,
    coercible_dtos: &AHashSet<&str>,
    is_host_enum: bool,
) -> String {
    use crate::codegen::generators::enum_has_data_variants;
    let mut lines = vec![];

    if enum_has_data_variants(enum_def) {
        gen_data_enum_typeddicts(&mut lines, enum_def, coercible_dtos, is_host_enum);
    } else {
        lines.push(format!("class {}:", enum_def.name));
        if emit_docstrings && let Some(docstring) = pyi_docstring(&enum_def.doc, "    ") {
            lines.push(docstring);
        }
        for variant in &enum_def.variants {
            // Emit snake_case attribute names to match the #[pyo3(name = "...")] rename
            lines.push(format!(
                "    {}: {} = ...",
                to_python_enum_variant(&variant.name),
                enum_def.name
            ));
            if emit_docstrings && let Some(docstring) = pyi_docstring(&variant.doc, "    ") {
                lines.push(docstring);
            }
        }
        lines.push("    def __init__(self, value: int | str) -> None: ...".to_string());
    }

    lines.join("\n")
}

/// serde's default discriminator key, kept for enums that reach the tagged path without one.
const DEFAULT_TAG_FIELD: &str = "type";

/// The stub annotation for an adjacently tagged variant's payload, or `None` when the variant is
/// a unit variant and serde writes no content key for it at all.
///
/// A struct variant's payload is an object of its own named fields, which a TypedDict cannot spell
/// inline, so a companion TypedDict is emitted into `lines` and referenced by name.
fn adjacent_payload_type(lines: &mut Vec<String>, enum_def: &EnumDef, variant: &EnumVariant) -> Option<String> {
    if variant.fields.is_empty() {
        return None;
    }
    if variant.is_tuple && variant.fields.len() == 1 {
        return Some(python_type(&variant.fields[0].ty));
    }
    let payload_class = format!("{}{}Payload", enum_def.name, variant.name);
    lines.push(format!("class {payload_class}(TypedDict):"));
    for field in &variant.fields {
        let field_type = python_type(&field.ty);
        let field_type = if field.optional && !field_type.contains("| None") {
            format!("{field_type} | None")
        } else {
            field_type
        };
        lines.push(format!("    {}: {}", python_safe_name(&field.name), field_type));
    }
    lines.push(String::new());
    Some(payload_class)
}

/// Generate TypedDicts for each variant of a data enum, plus a Union type alias.
fn gen_data_enum_typeddicts(
    lines: &mut Vec<String>,
    enum_def: &EnumDef,
    coercible_dtos: &AHashSet<&str>,
    is_host_enum: bool,
) {
    let repr = crate::codegen::serde_enum_repr::serde_enum_repr(enum_def);
    let tag_field = repr.tag().unwrap_or(DEFAULT_TAG_FIELD);
    let rename_all = enum_def.serde_rename_all.as_deref();

    let mut variant_class_names = vec![];

    for variant in &enum_def.variants {
        let class_name = format!("{}{}Variant", enum_def.name, variant.name);
        variant_class_names.push(class_name.clone());

        let tag_value =
            crate::codegen::naming::wire_variant_value(&variant.name, variant.serde_rename.as_deref(), rename_all);

        // serde's adjacent form nests the whole payload under the content key, so the variant's
        // TypedDict declares that one key. A struct variant's payload is an object in its own
        // right and gets its own TypedDict; a newtype variant's is whatever it wraps. ~keep
        let payload_type_name = repr
            .content()
            .and_then(|_| adjacent_payload_type(lines, enum_def, variant));

        lines.push(format!("class {}(TypedDict):", class_name));

        lines.push(format!("    {}: Literal[\"{}\"]", tag_field, tag_value));

        match (repr.content(), payload_type_name) {
            (Some(content_field), Some(payload_type)) => {
                lines.push(format!("    {content_field}: {payload_type}"));
            }
            (Some(_), None) => {}
            (None, _) => {
                for field in &variant.fields {
                    let field_type = python_type(&field.ty);
                    let field_type = if field.optional && !field_type.contains("| None") {
                        format!("{} | None", field_type)
                    } else {
                        field_type
                    };
                    lines.push(format!("    {}: {}", python_safe_name(&field.name), field_type));
                }
            }
        }

        lines.push("".to_string());
    }

    lines.push(format!("class {}:", enum_def.name));
    lines.push(format!("    {}: str", tag_field));
    gen_data_enum_variant_constructor_stubs(lines, enum_def, coercible_dtos, is_host_enum);
    // The runtime wrapper exposes a `#[new]` accepting a tag string, a `{"type": ...}` dict, or
    // serde-based `#[new]` is omitted and the type is return-only. Mirror that here so a converter
    if !crate::codegen::generators::enum_has_sanitized_fields(enum_def) {
        lines.push(
            "    def __init__(self, value: dict[str, Any] | str | None = None, **kwargs: Any) -> None: ...".to_string(),
        );
    }
    lines.push("    def __str__(self) -> str: ...".to_string());
    lines.push("    def __repr__(self) -> str: ...".to_string());
}

/// Emit a `@staticmethod` stub for each per-variant constructor the PyO3 binding exposes.
///
/// The runtime binding declares these under the bare snake_case host name (via
/// `#[pyo3(name = "<snake>")]`), so the stub declares the same public name. Each param type maps
/// through [`python_type`] — the same mapper the surrounding stub uses for fields — and the return
/// type is the enum itself. `collect_all_variant_constructors` owns the skip rules (unit / tuple /
/// `binding_excluded` / sanitized-field variants) so the stub and runtime binding stay aligned —
/// including for a variant whose snake_case name collides with a hand-written `impl EnumType { .. }`
/// method, since the runtime binding never forwards that method either (see its doc comment).
///
/// `is_host_enum` additionally excludes any variant
/// `gen_pyo3_enum_variant_constructors_content` (`codegen::generators::enums`) itself drops as an
/// unreachable FOREIGN cfg-gated variant -- without this the stub would advertise a
/// `@staticmethod` PyO3 never registers.
fn gen_data_enum_variant_constructor_stubs(
    lines: &mut Vec<String>,
    enum_def: &EnumDef,
    coercible_dtos: &AHashSet<&str>,
    is_host_enum: bool,
) {
    use crate::codegen::generators::{collect_all_variant_constructors, variant_constructor_is_reachable};

    let ctors: Vec<_> = collect_all_variant_constructors(enum_def)
        .into_iter()
        .filter(|ctor| {
            enum_def
                .variants
                .iter()
                .find(|v| v.name == ctor.variant_name)
                .is_some_and(|v| variant_constructor_is_reachable(v, is_host_enum))
        })
        .collect();

    const SHADOWABLE_BUILTINS: &[&str] = &["list", "dict", "set", "tuple", "frozenset", "type"];
    let shadowed: Vec<&str> = SHADOWABLE_BUILTINS
        .iter()
        .copied()
        .filter(|b| ctors.iter().any(|c| c.snake_name == *b))
        .collect();

    for ctor in &ctors {
        let params: Vec<String> = ctor
            .params
            .iter()
            .enumerate()
            .map(|(idx, p)| {
                let optional = p.optional || crate::codegen::shared::is_promoted_optional(&ctor.params, idx);
                let mut py_type = factory_param_type(&p.ty, coercible_dtos);
                for builtin in &shadowed {
                    py_type = py_type.replace(&format!("{builtin}["), &format!("builtins.{builtin}["));
                }
                let py_type = if optional && !py_type.contains("| None") {
                    format!("{py_type} | None")
                } else {
                    py_type
                };
                crate::backends::pyo3::template_env::render(
                    "stub_enum_variant_constructor_param.jinja",
                    minijinja::context! {
                        name => python_safe_name(&p.name),
                        py_type => py_type,
                        optional => optional,
                    },
                )
            })
            .collect();
        lines.push(crate::backends::pyo3::template_env::render(
            "stub_enum_variant_constructor.jinja",
            minijinja::context! {
                method_name => python_safe_name(&ctor.snake_name),
                params => params.join(", "),
                return_type => &enum_def.name,
            },
        ));
    }
}

#[cfg(test)]
mod tests;