alef-backend-zig 0.14.26

use alef_codegen::keywords::zig_ident;
use alef_codegen::type_mapper::TypeMapper;
use alef_core::ir::{EnumDef, TypeDef, TypeRef};

use crate::type_map::ZigMapper;

use super::helpers::emit_cleaned_zig_doc;

pub(crate) fn emit_type(ty: &TypeDef, out: &mut String) {
    emit_cleaned_zig_doc(out, &ty.doc, "");
    out.push_str(&format!("pub const {} = struct {{\n", ty.name));
    for field in &ty.fields {
        let ty_str = zig_field_type(&field.ty, field.optional);
        out.push_str(&format!("    {}: {},\n", zig_ident(&field.name), ty_str));
    }
    out.push_str("};\n");
}

pub(crate) fn emit_enum(en: &EnumDef, out: &mut String) {
    emit_cleaned_zig_doc(out, &en.doc, "");
    let all_unit = en.variants.iter().all(|v| v.fields.is_empty());
    if all_unit {
        out.push_str(&format!("pub const {} = enum {{\n", en.name));
        for variant in &en.variants {
            out.push_str(&format!("    {},\n", zig_ident(&to_snake_case(&variant.name))));
        }
        out.push_str("};\n");
    } else {
        out.push_str(&format!("pub const {} = union(enum) {{\n", en.name));
        for variant in &en.variants {
            let tag = zig_ident(&to_snake_case(&variant.name));
            if variant.fields.is_empty() {
                out.push_str(&format!("    {tag}: void,\n"));
            } else if variant.fields.len() == 1 {
                let ty_str = zig_field_type(&variant.fields[0].ty, variant.fields[0].optional);
                out.push_str(&format!("    {tag}: {ty_str},\n"));
            } else {
                out.push_str(&format!("    {tag}: struct {{\n"));
                for f in &variant.fields {
                    let name = if f.name.is_empty() {
                        "value".into()
                    } else {
                        zig_ident(&f.name)
                    };
                    let ty_str = zig_field_type(&f.ty, f.optional);
                    out.push_str(&format!("        {name}: {ty_str},\n"));
                }
                out.push_str("    },\n");
            }
        }
        out.push_str("};\n");
    }
}

pub(crate) fn zig_field_type(ty: &TypeRef, optional: bool) -> String {
    let mapper = ZigMapper;
    let inner = mapper.map_type(ty);
    if optional { format!("?{inner}") } else { inner }
}

pub(crate) fn to_snake_case(name: &str) -> String {
    let mut out = String::new();
    for (i, ch) in name.chars().enumerate() {
        if ch.is_uppercase() {
            if i > 0 {
                out.push('_');
            }
            out.extend(ch.to_lowercase());
        } else {
            out.push(ch);
        }
    }
    out
}