alef_e2e/codegen/

elixir.rs

//! Elixir e2e test generator using ExUnit.

use crate::config::E2eConfig;
use crate::escape::{escape_elixir, sanitize_filename, sanitize_ident};
use crate::field_access::FieldResolver;
use crate::fixture::{Assertion, CallbackAction, Fixture, FixtureGroup, HttpFixture, ValidationErrorExpectation};
use alef_core::backend::GeneratedFile;
use alef_core::config::AlefConfig;
use alef_core::hash::{self, CommentStyle};
use alef_core::template_versions as tv;
use anyhow::Result;
use heck::ToSnakeCase;
use std::collections::HashMap;
use std::fmt::Write as FmtWrite;
use std::path::PathBuf;

use super::E2eCodegen;
use super::client;

/// Elixir e2e code generator.
pub struct ElixirCodegen;

impl E2eCodegen for ElixirCodegen {
    fn generate(
        &self,
        groups: &[FixtureGroup],
        e2e_config: &E2eConfig,
        alef_config: &AlefConfig,
    ) -> Result<Vec<GeneratedFile>> {
        let lang = self.language_name();
        let output_base = PathBuf::from(e2e_config.effective_output()).join(lang);

        let mut files = Vec::new();

        // Resolve call config with overrides.
        let call = &e2e_config.call;
        let overrides = call.overrides.get(lang);
        let raw_module = overrides
            .and_then(|o| o.module.as_ref())
            .cloned()
            .unwrap_or_else(|| call.module.clone());
        // Convert module path to Elixir PascalCase if it looks like snake_case
        // (e.g., "html_to_markdown" -> "HtmlToMarkdown").
        // If the override already contains "." (e.g., "Elixir.HtmlToMarkdown"), use as-is.
        let module_path = if raw_module.contains('.') || raw_module.chars().next().is_some_and(|c| c.is_uppercase()) {
            raw_module.clone()
        } else {
            elixir_module_name(&raw_module)
        };
        let base_function_name = overrides
            .and_then(|o| o.function.as_ref())
            .cloned()
            .unwrap_or_else(|| call.function.clone());
        // Elixir facade exports async variants with `_async` suffix when the call is async.
        // Append the suffix only if not already present.
        let function_name = if call.r#async && !base_function_name.ends_with("_async") {
            format!("{base_function_name}_async")
        } else {
            base_function_name
        };
        let options_type = overrides.and_then(|o| o.options_type.clone());
        let options_default_fn = overrides.and_then(|o| o.options_via.clone());
        let empty_enum_fields = HashMap::new();
        let enum_fields = overrides.map(|o| &o.enum_fields).unwrap_or(&empty_enum_fields);
        let handle_struct_type = overrides.and_then(|o| o.handle_struct_type.clone());
        let empty_atom_fields = std::collections::HashSet::new();
        let handle_atom_list_fields = overrides
            .map(|o| &o.handle_atom_list_fields)
            .unwrap_or(&empty_atom_fields);
        let result_var = &call.result_var;

        // Check if any fixture in any group is an HTTP test.
        let has_http_tests = groups.iter().any(|g| g.fixtures.iter().any(|f| f.is_http_test()));
        let has_nif_tests = groups.iter().any(|g| g.fixtures.iter().any(|f| !f.is_http_test()));

        // Resolve package reference (path or version) for the NIF dependency.
        let pkg_ref = e2e_config.resolve_package(lang);
        let pkg_path = if has_nif_tests {
            pkg_ref.as_ref().and_then(|p| p.path.as_deref()).unwrap_or("")
        } else {
            ""
        };

        // Generate mix.exs. The dep atom must match the binding package's
        // mix `app:` value, not the crate name. Use the configured
        // `[elixir].app_name` (the same source the package's own mix.exs
        // uses); fall back to the crate name only when unset. Without this,
        // mix's path-dep resolution silently misroutes — the path-dep's
        // own deps (notably `:rustler_precompiled`) never load during its
        // compilation and the parent build fails with `RustlerPrecompiled
        // is not loaded`.
        let pkg_atom = alef_config.elixir_app_name();
        files.push(GeneratedFile {
            path: output_base.join("mix.exs"),
            content: render_mix_exs(&pkg_atom, pkg_path, e2e_config.dep_mode, has_http_tests, has_nif_tests),
            generated_header: false,
        });

        // Generate lib/e2e_elixir.ex — required so the mix project compiles.
        files.push(GeneratedFile {
            path: output_base.join("lib").join("e2e_elixir.ex"),
            content: "defmodule E2eElixir do\n  @moduledoc false\nend\n".to_string(),
            generated_header: false,
        });

        // Generate test_helper.exs.
        files.push(GeneratedFile {
            path: output_base.join("test").join("test_helper.exs"),
            content: render_test_helper(has_http_tests),
            generated_header: false,
        });

        // Generate test files per category.
        for group in groups {
            let active: Vec<&Fixture> = group
                .fixtures
                .iter()
                .filter(|f| f.skip.as_ref().is_none_or(|s| !s.should_skip(lang)))
                .collect();

            if active.is_empty() {
                continue;
            }

            let filename = format!("{}_test.exs", sanitize_filename(&group.category));
            let field_resolver = FieldResolver::new(
                &e2e_config.fields,
                &e2e_config.fields_optional,
                &e2e_config.result_fields,
                &e2e_config.fields_array,
            );
            let content = render_test_file(
                &group.category,
                &active,
                e2e_config,
                &module_path,
                &function_name,
                result_var,
                &e2e_config.call.args,
                &field_resolver,
                options_type.as_deref(),
                options_default_fn.as_deref(),
                enum_fields,
                handle_struct_type.as_deref(),
                handle_atom_list_fields,
            );
            files.push(GeneratedFile {
                path: output_base.join("test").join(filename),
                content,
                generated_header: true,
            });
        }

        Ok(files)
    }

    fn language_name(&self) -> &'static str {
        "elixir"
    }
}

fn render_test_helper(has_http_tests: bool) -> String {
    if has_http_tests {
        r#"ExUnit.start()

# Spawn mock-server binary and set MOCK_SERVER_URL for all tests.
mock_server_bin = Path.expand("../../rust/target/release/mock-server", __DIR__)
fixtures_dir = Path.expand("../../../fixtures", __DIR__)

if File.exists?(mock_server_bin) do
  port = Port.open({:spawn_executable, mock_server_bin}, [
    :binary,
    :line,
    args: [fixtures_dir]
  ])
  receive do
    {^port, {:data, {:eol, "MOCK_SERVER_URL=" <> url}}} ->
      System.put_env("MOCK_SERVER_URL", url)
  after
    30_000 ->
      raise "mock-server startup timeout"
  end
end
"#
        .to_string()
    } else {
        "ExUnit.start()\n".to_string()
    }
}

fn render_mix_exs(
    pkg_name: &str,
    pkg_path: &str,
    dep_mode: crate::config::DependencyMode,
    has_http_tests: bool,
    has_nif_tests: bool,
) -> String {
    let mut out = String::new();
    let _ = writeln!(out, "defmodule E2eElixir.MixProject do");
    let _ = writeln!(out, "  use Mix.Project");
    let _ = writeln!(out);
    let _ = writeln!(out, "  def project do");
    let _ = writeln!(out, "    [");
    let _ = writeln!(out, "      app: :e2e_elixir,");
    let _ = writeln!(out, "      version: \"0.1.0\",");
    let _ = writeln!(out, "      elixir: \"~> 1.14\",");
    let _ = writeln!(out, "      deps: deps()");
    let _ = writeln!(out, "    ]");
    let _ = writeln!(out, "  end");
    let _ = writeln!(out);
    let _ = writeln!(out, "  defp deps do");
    let _ = writeln!(out, "    [");

    // Build the list of deps, then join with commas to avoid double-commas.
    let mut deps: Vec<String> = Vec::new();

    // Add the binding NIF dependency when there are non-HTTP tests.
    if has_nif_tests && !pkg_path.is_empty() {
        let pkg_atom = pkg_name;
        let nif_dep = match dep_mode {
            crate::config::DependencyMode::Local => {
                format!("      {{:{pkg_atom}, path: \"{pkg_path}\"}}")
            }
            crate::config::DependencyMode::Registry => {
                // Registry mode: pkg_path is repurposed as the version string.
                format!("      {{:{pkg_atom}, \"{pkg_path}\"}}")
            }
        };
        deps.push(nif_dep);
        // rustler_precompiled provides the precompiled NIF loader.
        deps.push(format!(
            "      {{:rustler_precompiled, \"{rp}\"}}",
            rp = tv::hex::RUSTLER_PRECOMPILED
        ));
        // rustler must be a direct dep in the consumer project for force_build to work.
        deps.push(format!(
            "      {{:rustler, \"{rustler}\", optional: true, runtime: false}}",
            rustler = tv::hex::RUSTLER
        ));
    }

    // Add Req + Jason for HTTP testing.
    if has_http_tests {
        deps.push(format!("      {{:req, \"{req}\"}}", req = tv::hex::REQ));
        deps.push(format!("      {{:jason, \"{jason}\"}}", jason = tv::hex::JASON));
    }

    let _ = writeln!(out, "{}", deps.join(",\n"));
    let _ = writeln!(out, "    ]");
    let _ = writeln!(out, "  end");
    let _ = writeln!(out, "end");
    out
}

#[allow(clippy::too_many_arguments)]
fn render_test_file(
    category: &str,
    fixtures: &[&Fixture],
    e2e_config: &E2eConfig,
    module_path: &str,
    function_name: &str,
    result_var: &str,
    args: &[crate::config::ArgMapping],
    field_resolver: &FieldResolver,
    options_type: Option<&str>,
    options_default_fn: Option<&str>,
    enum_fields: &HashMap<String, String>,
    handle_struct_type: Option<&str>,
    handle_atom_list_fields: &std::collections::HashSet<String>,
) -> String {
    let mut out = String::new();
    out.push_str(&hash::header(CommentStyle::Hash));
    let _ = writeln!(out, "# E2e tests for category: {category}");
    let _ = writeln!(out, "defmodule E2e.{}Test do", elixir_module_name(category));

    // Add client helper when there are HTTP fixtures in this group.
    let has_http = fixtures.iter().any(|f| f.is_http_test());

    // Use async: false for NIF tests — concurrent Tokio runtimes created by DirtyCpu NIFs
    // on ARM64 macOS cause SIGBUS when tests run in parallel. HTTP-only tests can stay async.
    let async_flag = if has_http { "true" } else { "false" };
    let _ = writeln!(out, "  use ExUnit.Case, async: {async_flag}");

    if has_http {
        let _ = writeln!(out);
        let _ = writeln!(out, "  defp mock_server_url do");
        let _ = writeln!(
            out,
            "    System.get_env(\"MOCK_SERVER_URL\") || \"http://localhost:8080\""
        );
        let _ = writeln!(out, "  end");
    }

    let _ = writeln!(out);

    for (i, fixture) in fixtures.iter().enumerate() {
        if let Some(http) = &fixture.http {
            render_http_test_case(&mut out, fixture, http);
        } else {
            render_test_case(
                &mut out,
                fixture,
                e2e_config,
                module_path,
                function_name,
                result_var,
                args,
                field_resolver,
                options_type,
                options_default_fn,
                enum_fields,
                handle_struct_type,
                handle_atom_list_fields,
            );
        }
        if i + 1 < fixtures.len() {
            let _ = writeln!(out);
        }
    }

    let _ = writeln!(out, "end");
    out
}

// ---------------------------------------------------------------------------
// HTTP test rendering
// ---------------------------------------------------------------------------

/// HTTP methods that Finch (Req's underlying HTTP client) does not support.
/// Tests using these methods are emitted with `@tag :skip` so they don't fail.
const FINCH_UNSUPPORTED_METHODS: &[&str] = &["TRACE", "CONNECT"];

/// HTTP methods that Req exposes as convenience functions.
/// All others must be called via `Req.request(method: :METHOD, ...)`.
const REQ_CONVENIENCE_METHODS: &[&str] = &["get", "post", "put", "patch", "delete", "head"];

/// Thin renderer that emits ExUnit `describe` + `test` blocks targeting a mock
/// server via `Req`. Satisfies [`client::TestClientRenderer`] so the shared
/// [`client::http_call::render_http_test`] driver drives the call sequence.
struct ElixirTestClientRenderer<'a> {
    /// The fixture id is needed in [`render_call`] to build the mock server URL
    /// (`mock_server_url()/fixtures/<id>`).
    fixture_id: &'a str,
    /// Expected response status, needed to disable Req's redirect-following for 3xx.
    expected_status: u16,
}

impl<'a> client::TestClientRenderer for ElixirTestClientRenderer<'a> {
    fn language_name(&self) -> &'static str {
        "elixir"
    }

    /// Emit `describe "{fn_name}" do` + inner `test "METHOD PATH - description" do`.
    ///
    /// When `skip_reason` is `Some`, emit `@tag :skip` before the test block so
    /// ExUnit skips it; the shared driver short-circuits before emitting any
    /// assertions and then calls `render_test_close` for symmetry.
    fn render_test_open(&self, out: &mut String, fn_name: &str, description: &str, skip_reason: Option<&str>) {
        let escaped_description = description.replace('"', "\\\"");
        let _ = writeln!(out, "  describe \"{fn_name}\" do");
        if skip_reason.is_some() {
            let _ = writeln!(out, "    @tag :skip");
        }
        let _ = writeln!(out, "    test \"{escaped_description}\" do");
    }

    /// Close the inner `test` block and the outer `describe` block.
    fn render_test_close(&self, out: &mut String) {
        let _ = writeln!(out, "    end");
        let _ = writeln!(out, "  end");
    }

    /// Emit a `Req` request to the mock server using `mock_server_url()/fixtures/<id>`.
    fn render_call(&self, out: &mut String, ctx: &client::CallCtx<'_>) {
        let method = ctx.method.to_lowercase();
        let mut opts: Vec<String> = Vec::new();

        if let Some(body) = ctx.body {
            let elixir_val = json_to_elixir(body);
            opts.push(format!("json: {elixir_val}"));
        }

        if !ctx.headers.is_empty() {
            let header_pairs: Vec<String> = ctx
                .headers
                .iter()
                .map(|(k, v)| format!("{{\"{}\", \"{}\"}}", escape_elixir(k), escape_elixir(v)))
                .collect();
            opts.push(format!("headers: [{}]", header_pairs.join(", ")));
        }

        if !ctx.cookies.is_empty() {
            let cookie_str = ctx
                .cookies
                .iter()
                .map(|(k, v)| format!("{k}={v}"))
                .collect::<Vec<_>>()
                .join("; ");
            opts.push(format!("headers: [{{\"cookie\", \"{}\"}}]", escape_elixir(&cookie_str)));
        }

        if !ctx.query_params.is_empty() {
            let pairs: Vec<String> = ctx
                .query_params
                .iter()
                .map(|(k, v)| {
                    let val_str = match v {
                        serde_json::Value::String(s) => s.clone(),
                        other => other.to_string(),
                    };
                    format!("{{\"{}\", \"{}\"}}", escape_elixir(k), escape_elixir(&val_str))
                })
                .collect();
            opts.push(format!("params: [{}]", pairs.join(", ")));
        }

        // When the expected response is a redirect (3xx), disable automatic redirect
        // following so the test can assert the redirect status and Location header.
        if (300..400).contains(&self.expected_status) {
            opts.push("redirect: false".to_string());
        }

        let fixture_id = escape_elixir(self.fixture_id);
        let url_expr = format!("\"#{{mock_server_url()}}/fixtures/{fixture_id}\"");

        if REQ_CONVENIENCE_METHODS.contains(&method.as_str()) {
            if opts.is_empty() {
                let _ = writeln!(out, "      {{:ok, response}} = Req.{method}(url: {url_expr})");
            } else {
                let opts_str = opts.join(", ");
                let _ = writeln!(
                    out,
                    "      {{:ok, response}} = Req.{method}(url: {url_expr}, {opts_str})"
                );
            }
        } else {
            opts.insert(0, format!("method: :{method}"));
            opts.insert(1, format!("url: {url_expr}"));
            let opts_str = opts.join(", ");
            let _ = writeln!(out, "      {{:ok, response}} = Req.request({opts_str})");
        }
    }

    fn render_assert_status(&self, out: &mut String, response_var: &str, status: u16) {
        let _ = writeln!(out, "      assert {response_var}.status == {status}");
    }

    /// Emit a header assertion.
    ///
    /// Handles the special tokens `<<present>>`, `<<absent>>`, `<<uuid>>`.
    /// Skips the `connection` header (hop-by-hop, stripped by Req/Mint).
    fn render_assert_header(&self, out: &mut String, response_var: &str, name: &str, expected: &str) {
        let header_key = name.to_lowercase();
        // Req (via Mint) strips hop-by-hop headers; asserting on them is meaningless.
        if header_key == "connection" {
            return;
        }
        let key_lit = format!("\"{}\"", escape_elixir(&header_key));
        let get_header_expr = format!(
            "Enum.find_value({response_var}.headers, fn {{k, v}} -> if String.downcase(k) == {key_lit}, do: List.first(List.wrap(v)) end)"
        );
        match expected {
            "<<present>>" => {
                let _ = writeln!(out, "      assert {get_header_expr} != nil");
            }
            "<<absent>>" => {
                let _ = writeln!(out, "      assert {get_header_expr} == nil");
            }
            "<<uuid>>" => {
                let var = sanitize_ident(&header_key);
                let _ = writeln!(out, "      header_val_{var} = {get_header_expr}");
                let _ = writeln!(
                    out,
                    "      assert Regex.match?(~r/^[0-9a-f]{{8}}-[0-9a-f]{{4}}-[0-9a-f]{{4}}-[0-9a-f]{{4}}-[0-9a-f]{{12}}$/i, to_string(header_val_{var}))"
                );
            }
            literal => {
                let val_lit = format!("\"{}\"", escape_elixir(literal));
                let _ = writeln!(out, "      assert {get_header_expr} == {val_lit}");
            }
        }
    }

    /// Emit a full JSON body equality assertion.
    ///
    /// Req auto-decodes `application/json` bodies; when the response body is a
    /// binary (non-JSON content type), decode it with `Jason.decode!` first.
    fn render_assert_json_body(&self, out: &mut String, response_var: &str, expected: &serde_json::Value) {
        let elixir_val = json_to_elixir(expected);
        match expected {
            serde_json::Value::Object(_) | serde_json::Value::Array(_) => {
                let _ = writeln!(
                    out,
                    "      body_decoded = if is_binary({response_var}.body), do: Jason.decode!({response_var}.body), else: {response_var}.body"
                );
                let _ = writeln!(out, "      assert body_decoded == {elixir_val}");
            }
            _ => {
                let _ = writeln!(out, "      assert {response_var}.body == {elixir_val}");
            }
        }
    }

    /// Emit partial body assertions: one assertion per key in `expected`.
    fn render_assert_partial_body(&self, out: &mut String, response_var: &str, expected: &serde_json::Value) {
        if let Some(obj) = expected.as_object() {
            let _ = writeln!(
                out,
                "      decoded_body = if is_binary({response_var}.body), do: Jason.decode!({response_var}.body), else: {response_var}.body"
            );
            for (key, val) in obj {
                let key_lit = format!("\"{}\"", escape_elixir(key));
                let elixir_val = json_to_elixir(val);
                let _ = writeln!(out, "      assert decoded_body[{key_lit}] == {elixir_val}");
            }
        }
    }

    /// Emit validation-error assertions, checking each expected `msg` appears in
    /// the encoded response body.
    fn render_assert_validation_errors(
        &self,
        out: &mut String,
        response_var: &str,
        errors: &[ValidationErrorExpectation],
    ) {
        for err in errors {
            let msg_lit = format!("\"{}\"", escape_elixir(&err.msg));
            let _ = writeln!(
                out,
                "      assert String.contains?(Jason.encode!({response_var}.body), {msg_lit})"
            );
        }
    }
}

/// Render an ExUnit `describe` + `test` block for an HTTP server test fixture.
///
/// Delegates to [`client::http_call::render_http_test`] after the one
/// Elixir-specific pre-condition: HTTP methods unsupported by Finch (the
/// underlying Req adapter) are emitted with `@tag :skip` directly.
fn render_http_test_case(out: &mut String, fixture: &Fixture, http: &HttpFixture) {
    let method = http.request.method.to_uppercase();

    // Finch does not support TRACE/CONNECT — emit a skipped test stub directly
    // rather than routing through the shared driver, which would assert on the
    // response and fail.
    if FINCH_UNSUPPORTED_METHODS.contains(&method.as_str()) {
        let test_name = sanitize_ident(&fixture.id);
        let description = fixture.description.replace('"', "\\\"");
        let path = &http.request.path;
        let _ = writeln!(out, "  describe \"{test_name}\" do");
        let _ = writeln!(out, "    @tag :skip");
        let _ = writeln!(out, "    test \"{method} {path} - {description}\" do");
        let _ = writeln!(out, "    end");
        let _ = writeln!(out, "  end");
        return;
    }

    let renderer = ElixirTestClientRenderer {
        fixture_id: &fixture.id,
        expected_status: http.expected_response.status_code,
    };
    client::http_call::render_http_test(out, &renderer, fixture);
}

// ---------------------------------------------------------------------------
// Function-call test rendering
// ---------------------------------------------------------------------------

#[allow(clippy::too_many_arguments)]
fn render_test_case(
    out: &mut String,
    fixture: &Fixture,
    e2e_config: &E2eConfig,
    default_module_path: &str,
    default_function_name: &str,
    default_result_var: &str,
    args: &[crate::config::ArgMapping],
    field_resolver: &FieldResolver,
    options_type: Option<&str>,
    options_default_fn: Option<&str>,
    enum_fields: &HashMap<String, String>,
    handle_struct_type: Option<&str>,
    handle_atom_list_fields: &std::collections::HashSet<String>,
) {
    let test_name = sanitize_ident(&fixture.id);
    let description = fixture.description.replace('"', "\\\"");

    // Non-HTTP non-mock_response fixtures (e.g. AsyncAPI, WebSocket, OpenRPC
    // protocol-only fixtures) cannot be tested via the configured `[e2e.call]`
    // function when the binding does not expose it. Emit a documented `@tag :skip`
    // test so the suite stays compilable. HTTP fixtures dispatch via render_http_test_case
    // and never reach here.
    if fixture.mock_response.is_none() {
        let _ = writeln!(out, "  describe \"{test_name}\" do");
        let _ = writeln!(out, "    @tag :skip");
        let _ = writeln!(out, "    test \"{description}\" do");
        let _ = writeln!(
            out,
            "      # non-HTTP fixture: Elixir binding does not expose a callable for the configured `[e2e.call]` function"
        );
        let _ = writeln!(out, "      :ok");
        let _ = writeln!(out, "    end");
        let _ = writeln!(out, "  end");
        return;
    }

    // Resolve per-fixture call config (falls back to default if fixture.call is None).
    let call_config = e2e_config.resolve_call(fixture.call.as_deref());
    let lang = "elixir";
    let call_overrides = call_config.overrides.get(lang);

    // Compute module_path and function_name from the resolved call config,
    // applying Elixir-specific PascalCase conversion.
    let (module_path, function_name, result_var) = if fixture.call.is_some() {
        let raw_module = call_overrides
            .and_then(|o| o.module.as_ref())
            .cloned()
            .unwrap_or_else(|| call_config.module.clone());
        let resolved_module = if raw_module.contains('.') || raw_module.chars().next().is_some_and(|c| c.is_uppercase())
        {
            raw_module.clone()
        } else {
            elixir_module_name(&raw_module)
        };
        let base_fn = call_overrides
            .and_then(|o| o.function.as_ref())
            .cloned()
            .unwrap_or_else(|| call_config.function.clone());
        let resolved_fn = if call_config.r#async && !base_fn.ends_with("_async") {
            format!("{base_fn}_async")
        } else {
            base_fn
        };
        (resolved_module, resolved_fn, call_config.result_var.clone())
    } else {
        (
            default_module_path.to_string(),
            default_function_name.to_string(),
            default_result_var.to_string(),
        )
    };

    let expects_error = fixture.assertions.iter().any(|a| a.assertion_type == "error");

    // When the fixture uses a named call, use the args and options from that call's config.
    let (
        effective_args,
        effective_options_type,
        effective_options_default_fn,
        effective_enum_fields,
        effective_handle_struct_type,
        effective_handle_atom_list_fields,
    );
    let empty_enum_fields_local: HashMap<String, String>;
    let empty_atom_fields_local: std::collections::HashSet<String>;
    let (
        resolved_args,
        resolved_options_type,
        resolved_options_default_fn,
        resolved_enum_fields_ref,
        resolved_handle_struct_type,
        resolved_handle_atom_list_fields_ref,
    ) = if fixture.call.is_some() {
        let co = call_config.overrides.get(lang);
        effective_args = call_config.args.as_slice();
        effective_options_type = co.and_then(|o| o.options_type.as_deref());
        effective_options_default_fn = co.and_then(|o| o.options_via.as_deref());
        empty_enum_fields_local = HashMap::new();
        effective_enum_fields = co.map(|o| &o.enum_fields).unwrap_or(&empty_enum_fields_local);
        effective_handle_struct_type = co.and_then(|o| o.handle_struct_type.as_deref());
        empty_atom_fields_local = std::collections::HashSet::new();
        effective_handle_atom_list_fields = co
            .map(|o| &o.handle_atom_list_fields)
            .unwrap_or(&empty_atom_fields_local);
        (
            effective_args,
            effective_options_type,
            effective_options_default_fn,
            effective_enum_fields,
            effective_handle_struct_type,
            effective_handle_atom_list_fields,
        )
    } else {
        (
            args as &[_],
            options_type,
            options_default_fn,
            enum_fields,
            handle_struct_type,
            handle_atom_list_fields,
        )
    };

    let (mut setup_lines, args_str) = build_args_and_setup(
        &fixture.input,
        resolved_args,
        &module_path,
        resolved_options_type,
        resolved_options_default_fn,
        resolved_enum_fields_ref,
        &fixture.id,
        resolved_handle_struct_type,
        resolved_handle_atom_list_fields_ref,
    );

    // Build visitor if present — must happen before emitting setup_lines so the
    // visitor setup line is included in the loop below.
    let final_args = if let Some(visitor_spec) = &fixture.visitor {
        let visitor_var = build_elixir_visitor(&mut setup_lines, visitor_spec);
        format!("{args_str}, {visitor_var}")
    } else {
        args_str
    };

    let _ = writeln!(out, "  describe \"{test_name}\" do");
    let _ = writeln!(out, "    test \"{description}\" do");

    for line in &setup_lines {
        let _ = writeln!(out, "      {line}");
    }

    let returns_result = call_config.returns_result;

    if expects_error {
        if returns_result {
            let _ = writeln!(
                out,
                "      assert {{:error, _}} = {module_path}.{function_name}({final_args})"
            );
        } else {
            // Non-Result function — just call and discard; error detection not meaningful.
            let _ = writeln!(out, "      _result = {module_path}.{function_name}({final_args})");
        }
        let _ = writeln!(out, "    end");
        let _ = writeln!(out, "  end");
        return;
    }

    if returns_result {
        let _ = writeln!(
            out,
            "      {{:ok, {result_var}}} = {module_path}.{function_name}({final_args})"
        );
    } else {
        // Non-Result function returns value directly (e.g., bool, String).
        let _ = writeln!(out, "      {result_var} = {module_path}.{function_name}({final_args})");
    }

    for assertion in &fixture.assertions {
        render_assertion(out, assertion, &result_var, field_resolver, &module_path);
    }

    let _ = writeln!(out, "    end");
    let _ = writeln!(out, "  end");
}

/// Build setup lines (e.g. handle creation) and the argument list for the function call.
///
/// Returns `(setup_lines, args_string)`.
#[allow(clippy::too_many_arguments)]
fn build_args_and_setup(
    input: &serde_json::Value,
    args: &[crate::config::ArgMapping],
    module_path: &str,
    options_type: Option<&str>,
    options_default_fn: Option<&str>,
    enum_fields: &HashMap<String, String>,
    fixture_id: &str,
    _handle_struct_type: Option<&str>,
    _handle_atom_list_fields: &std::collections::HashSet<String>,
) -> (Vec<String>, String) {
    if args.is_empty() {
        return (Vec::new(), json_to_elixir(input));
    }

    let mut setup_lines: Vec<String> = Vec::new();
    let mut parts: Vec<String> = Vec::new();

    for arg in args {
        if arg.arg_type == "mock_url" {
            setup_lines.push(format!(
                "{} = System.get_env(\"MOCK_SERVER_URL\") <> \"/fixtures/{fixture_id}\"",
                arg.name,
            ));
            parts.push(arg.name.clone());
            continue;
        }

        if arg.arg_type == "handle" {
            // Generate a create_{name} call using {:ok, name} = ... pattern.
            // The NIF now accepts config as an optional JSON string (not a NifStruct/NifMap)
            // so that partial maps work: serde_json::from_str respects #[serde(default)].
            let constructor_name = format!("create_{}", arg.name.to_snake_case());
            let field = arg.field.strip_prefix("input.").unwrap_or(&arg.field);
            let config_value = input.get(field).unwrap_or(&serde_json::Value::Null);
            let name = &arg.name;
            if config_value.is_null()
                || config_value.is_object() && config_value.as_object().is_some_and(|o| o.is_empty())
            {
                setup_lines.push(format!("{{:ok, {name}}} = {module_path}.{constructor_name}(nil)"));
            } else {
                // Serialize the config map to a JSON string with Jason so that Rust can
                // deserialize it with serde_json and apply field defaults for missing keys.
                let json_str = serde_json::to_string(config_value).unwrap_or_else(|_| "{}".to_string());
                let escaped = escape_elixir(&json_str);
                setup_lines.push(format!("{name}_config = \"{escaped}\""));
                setup_lines.push(format!(
                    "{{:ok, {name}}} = {module_path}.{constructor_name}({name}_config)",
                ));
            }
            parts.push(arg.name.clone());
            continue;
        }

        let field = arg.field.strip_prefix("input.").unwrap_or(&arg.field);
        let val = input.get(field);
        match val {
            None | Some(serde_json::Value::Null) if arg.optional => {
                // Elixir functions have fixed positional arity — pass nil for optional args
                // rather than skipping them, so the call site has the correct arity.
                parts.push("nil".to_string());
                continue;
            }
            None | Some(serde_json::Value::Null) => {
                // Required arg with no fixture value: pass a language-appropriate default.
                let default_val = match arg.arg_type.as_str() {
                    "string" => "\"\"".to_string(),
                    "int" | "integer" => "0".to_string(),
                    "float" | "number" => "0.0".to_string(),
                    "bool" | "boolean" => "false".to_string(),
                    _ => "nil".to_string(),
                };
                parts.push(default_val);
            }
            Some(v) => {
                // For file_path args, prepend the path to the test_documents directory
                // relative to the e2e/elixir/ directory where `mix test` runs.
                if arg.arg_type == "file_path" {
                    if let Some(path_str) = v.as_str() {
                        let full_path = format!("../../test_documents/{path_str}");
                        parts.push(format!("\"{}\"", escape_elixir(&full_path)));
                        continue;
                    }
                }
                // For bytes args, use File.read! for file paths and Base.decode64! for base64.
                // Inline text (starts with '<', '{', '[' or contains spaces) is used as-is (UTF-8 binary).
                if arg.arg_type == "bytes" {
                    if let Some(raw) = v.as_str() {
                        let var_name = &arg.name;
                        if raw.starts_with('<') || raw.starts_with('{') || raw.starts_with('[') || raw.contains(' ') {
                            // Inline text — use as a binary string.
                            parts.push(format!("\"{}\"", escape_elixir(raw)));
                        } else {
                            let first = raw.chars().next().unwrap_or('\0');
                            let is_file_path = (first.is_ascii_alphanumeric() || first == '_')
                                && raw
                                    .find('/')
                                    .is_some_and(|slash_pos| slash_pos > 0 && raw[slash_pos + 1..].contains('.'));
                            if is_file_path {
                                // Looks like "dir/file.ext" — read from test_documents.
                                let full_path = format!("../../test_documents/{raw}");
                                let escaped = escape_elixir(&full_path);
                                setup_lines.push(format!("{var_name} = File.read!(\"{escaped}\")"));
                                parts.push(var_name.to_string());
                            } else {
                                // Treat as base64-encoded binary.
                                setup_lines.push(format!(
                                    "{var_name} = Base.decode64!(\"{}\", padding: false)",
                                    escape_elixir(raw)
                                ));
                                parts.push(var_name.to_string());
                            }
                        }
                        continue;
                    }
                }
                // For json_object args with options_type+options_via, build a proper struct.
                if arg.arg_type == "json_object" && !v.is_null() {
                    if let (Some(_opts_type), Some(options_fn), Some(obj)) =
                        (options_type, options_default_fn, v.as_object())
                    {
                        // Add setup line to initialize options from default function.
                        let options_var = "options";
                        setup_lines.push(format!("{options_var} = {module_path}.{options_fn}()"));

                        // For each field in the options object, add a struct update line.
                        for (k, vv) in obj.iter() {
                            let snake_key = k.to_snake_case();
                            let elixir_val = if let Some(_enum_type) = enum_fields.get(k) {
                                if let Some(s) = vv.as_str() {
                                    let snake_val = s.to_snake_case();
                                    // Use atom for enum values, not string
                                    format!(":{snake_val}")
                                } else {
                                    json_to_elixir(vv)
                                }
                            } else {
                                json_to_elixir(vv)
                            };
                            setup_lines.push(format!(
                                "{options_var} = %{{{options_var} | {snake_key}: {elixir_val}}}"
                            ));
                        }

                        // Push the variable name as the argument.
                        parts.push(options_var.to_string());
                        continue;
                    }
                    // When there's no options_type+options_via, the Elixir NIF expects a JSON
                    // string (Option<String> decoded by serde_json) rather than an Elixir map.
                    // Serialize the JSON value to a string literal here.
                    if !v.is_null() {
                        let json_str = serde_json::to_string(v).unwrap_or_else(|_| "{}".to_string());
                        let escaped = escape_elixir(&json_str);
                        parts.push(format!("\"{escaped}\""));
                        continue;
                    }
                }
                parts.push(json_to_elixir(v));
            }
        }
    }

    (setup_lines, parts.join(", "))
}

/// Returns true if the field expression is a numeric/integer expression
/// (e.g., a `length(...)` call) rather than a string.
fn is_numeric_expr(field_expr: &str) -> bool {
    field_expr.starts_with("length(")
}

fn render_assertion(
    out: &mut String,
    assertion: &Assertion,
    result_var: &str,
    field_resolver: &FieldResolver,
    module_path: &str,
) {
    // Handle synthetic / derived fields before the is_valid_for_result check
    // so they are never treated as struct field accesses on the result.
    if let Some(f) = &assertion.field {
        match f.as_str() {
            "chunks_have_content" => {
                let pred =
                    format!("Enum.all?({result_var}.chunks || [], fn c -> c.content != nil and c.content != \"\" end)");
                match assertion.assertion_type.as_str() {
                    "is_true" => {
                        let _ = writeln!(out, "      assert {pred}");
                    }
                    "is_false" => {
                        let _ = writeln!(out, "      refute {pred}");
                    }
                    _ => {
                        let _ = writeln!(
                            out,
                            "      # skipped: unsupported assertion type on synthetic field '{f}'"
                        );
                    }
                }
                return;
            }
            "chunks_have_embeddings" => {
                let pred = format!(
                    "Enum.all?({result_var}.chunks || [], fn c -> c.embedding != nil and c.embedding != [] end)"
                );
                match assertion.assertion_type.as_str() {
                    "is_true" => {
                        let _ = writeln!(out, "      assert {pred}");
                    }
                    "is_false" => {
                        let _ = writeln!(out, "      refute {pred}");
                    }
                    _ => {
                        let _ = writeln!(
                            out,
                            "      # skipped: unsupported assertion type on synthetic field '{f}'"
                        );
                    }
                }
                return;
            }
            // ---- EmbedResponse virtual fields ----
            // embed_texts returns [[float]] in Elixir — no wrapper struct.
            // result_var is the embedding matrix; use it directly.
            "embeddings" => {
                match assertion.assertion_type.as_str() {
                    "count_equals" => {
                        if let Some(val) = &assertion.value {
                            let ex_val = json_to_elixir(val);
                            let _ = writeln!(out, "      assert length({result_var}) == {ex_val}");
                        }
                    }
                    "count_min" => {
                        if let Some(val) = &assertion.value {
                            let ex_val = json_to_elixir(val);
                            let _ = writeln!(out, "      assert length({result_var}) >= {ex_val}");
                        }
                    }
                    "not_empty" => {
                        let _ = writeln!(out, "      assert {result_var} != []");
                    }
                    "is_empty" => {
                        let _ = writeln!(out, "      assert {result_var} == []");
                    }
                    _ => {
                        let _ = writeln!(
                            out,
                            "      # skipped: unsupported assertion type on synthetic field 'embeddings'"
                        );
                    }
                }
                return;
            }
            "embedding_dimensions" => {
                let expr = format!("(if {result_var} == [], do: 0, else: length(hd({result_var})))");
                match assertion.assertion_type.as_str() {
                    "equals" => {
                        if let Some(val) = &assertion.value {
                            let ex_val = json_to_elixir(val);
                            let _ = writeln!(out, "      assert {expr} == {ex_val}");
                        }
                    }
                    "greater_than" => {
                        if let Some(val) = &assertion.value {
                            let ex_val = json_to_elixir(val);
                            let _ = writeln!(out, "      assert {expr} > {ex_val}");
                        }
                    }
                    _ => {
                        let _ = writeln!(
                            out,
                            "      # skipped: unsupported assertion type on synthetic field 'embedding_dimensions'"
                        );
                    }
                }
                return;
            }
            "embeddings_valid" | "embeddings_finite" | "embeddings_non_zero" | "embeddings_normalized" => {
                let pred = match f.as_str() {
                    "embeddings_valid" => {
                        format!("Enum.all?({result_var}, fn e -> e != [] end)")
                    }
                    "embeddings_finite" => {
                        format!("Enum.all?({result_var}, fn e -> Enum.all?(e, fn v -> is_float(v) and v == v end) end)")
                    }
                    "embeddings_non_zero" => {
                        format!("Enum.all?({result_var}, fn e -> Enum.any?(e, fn v -> v != 0.0 end) end)")
                    }
                    "embeddings_normalized" => {
                        format!(
                            "Enum.all?({result_var}, fn e -> n = Enum.reduce(e, 0.0, fn v, acc -> acc + v * v end); abs(n - 1.0) < 1.0e-3 end)"
                        )
                    }
                    _ => unreachable!(),
                };
                match assertion.assertion_type.as_str() {
                    "is_true" => {
                        let _ = writeln!(out, "      assert {pred}");
                    }
                    "is_false" => {
                        let _ = writeln!(out, "      refute {pred}");
                    }
                    _ => {
                        let _ = writeln!(
                            out,
                            "      # skipped: unsupported assertion type on synthetic field '{f}'"
                        );
                    }
                }
                return;
            }
            // ---- keywords / keywords_count ----
            // Elixir ExtractionResult does not expose extracted_keywords; skip.
            "keywords" | "keywords_count" => {
                let _ = writeln!(
                    out,
                    "      # skipped: field '{f}' not available on Elixir ExtractionResult"
                );
                return;
            }
            _ => {}
        }
    }

    // Skip assertions on fields that don't exist on the result type.
    if let Some(f) = &assertion.field {
        if !f.is_empty() && !field_resolver.is_valid_for_result(f) {
            let _ = writeln!(out, "      # skipped: field '{f}' not available on result type");
            return;
        }
    }

    let field_expr = match &assertion.field {
        Some(f) if !f.is_empty() => field_resolver.accessor(f, "elixir", result_var),
        _ => result_var.to_string(),
    };

    // Only wrap in String.trim/0 when the expression is actually a string.
    // Numeric expressions (e.g., length(...)) must not be wrapped.
    let is_numeric = is_numeric_expr(&field_expr);
    let trimmed_field_expr = if is_numeric {
        field_expr.clone()
    } else {
        format!("String.trim({field_expr})")
    };

    match assertion.assertion_type.as_str() {
        "equals" => {
            if let Some(expected) = &assertion.value {
                let elixir_val = json_to_elixir(expected);
                // Apply String.trim only for string comparisons, not numeric ones.
                let is_string_expected = expected.is_string();
                if is_string_expected && !is_numeric {
                    let _ = writeln!(out, "      assert {trimmed_field_expr} == {elixir_val}");
                } else {
                    let _ = writeln!(out, "      assert {field_expr} == {elixir_val}");
                }
            }
        }
        "contains" => {
            if let Some(expected) = &assertion.value {
                let elixir_val = json_to_elixir(expected);
                // Use to_string() to handle atoms (enums) as well as strings
                let _ = writeln!(
                    out,
                    "      assert String.contains?(to_string({field_expr}), {elixir_val})"
                );
            }
        }
        "contains_all" => {
            if let Some(values) = &assertion.values {
                for val in values {
                    let elixir_val = json_to_elixir(val);
                    let _ = writeln!(
                        out,
                        "      assert String.contains?(to_string({field_expr}), {elixir_val})"
                    );
                }
            }
        }
        "not_contains" => {
            if let Some(expected) = &assertion.value {
                let elixir_val = json_to_elixir(expected);
                let _ = writeln!(
                    out,
                    "      refute String.contains?(to_string({field_expr}), {elixir_val})"
                );
            }
        }
        "not_empty" => {
            let _ = writeln!(out, "      assert {field_expr} != \"\"");
        }
        "is_empty" => {
            if is_numeric {
                // length(...) == 0
                let _ = writeln!(out, "      assert {field_expr} == 0");
            } else {
                // Handle nil (None) as empty
                let _ = writeln!(out, "      assert is_nil({field_expr}) or {trimmed_field_expr} == \"\"");
            }
        }
        "contains_any" => {
            if let Some(values) = &assertion.values {
                let items: Vec<String> = values.iter().map(json_to_elixir).collect();
                let list_str = items.join(", ");
                let _ = writeln!(
                    out,
                    "      assert Enum.any?([{list_str}], fn v -> String.contains?(to_string({field_expr}), v) end)"
                );
            }
        }
        "greater_than" => {
            if let Some(val) = &assertion.value {
                let elixir_val = json_to_elixir(val);
                let _ = writeln!(out, "      assert {field_expr} > {elixir_val}");
            }
        }
        "less_than" => {
            if let Some(val) = &assertion.value {
                let elixir_val = json_to_elixir(val);
                let _ = writeln!(out, "      assert {field_expr} < {elixir_val}");
            }
        }
        "greater_than_or_equal" => {
            if let Some(val) = &assertion.value {
                let elixir_val = json_to_elixir(val);
                let _ = writeln!(out, "      assert {field_expr} >= {elixir_val}");
            }
        }
        "less_than_or_equal" => {
            if let Some(val) = &assertion.value {
                let elixir_val = json_to_elixir(val);
                let _ = writeln!(out, "      assert {field_expr} <= {elixir_val}");
            }
        }
        "starts_with" => {
            if let Some(expected) = &assertion.value {
                let elixir_val = json_to_elixir(expected);
                let _ = writeln!(out, "      assert String.starts_with?({field_expr}, {elixir_val})");
            }
        }
        "ends_with" => {
            if let Some(expected) = &assertion.value {
                let elixir_val = json_to_elixir(expected);
                let _ = writeln!(out, "      assert String.ends_with?({field_expr}, {elixir_val})");
            }
        }
        "min_length" => {
            if let Some(val) = &assertion.value {
                if let Some(n) = val.as_u64() {
                    let _ = writeln!(out, "      assert String.length({field_expr}) >= {n}");
                }
            }
        }
        "max_length" => {
            if let Some(val) = &assertion.value {
                if let Some(n) = val.as_u64() {
                    let _ = writeln!(out, "      assert String.length({field_expr}) <= {n}");
                }
            }
        }
        "count_min" => {
            if let Some(val) = &assertion.value {
                if let Some(n) = val.as_u64() {
                    let _ = writeln!(out, "      assert length({field_expr}) >= {n}");
                }
            }
        }
        "count_equals" => {
            if let Some(val) = &assertion.value {
                if let Some(n) = val.as_u64() {
                    let _ = writeln!(out, "      assert length({field_expr}) == {n}");
                }
            }
        }
        "is_true" => {
            let _ = writeln!(out, "      assert {field_expr} == true");
        }
        "is_false" => {
            let _ = writeln!(out, "      assert {field_expr} == false");
        }
        "method_result" => {
            if let Some(method_name) = &assertion.method {
                let call_expr = build_elixir_method_call(result_var, method_name, assertion.args.as_ref(), module_path);
                let check = assertion.check.as_deref().unwrap_or("is_true");
                match check {
                    "equals" => {
                        if let Some(val) = &assertion.value {
                            let elixir_val = json_to_elixir(val);
                            let _ = writeln!(out, "      assert {call_expr} == {elixir_val}");
                        }
                    }
                    "is_true" => {
                        let _ = writeln!(out, "      assert {call_expr} == true");
                    }
                    "is_false" => {
                        let _ = writeln!(out, "      assert {call_expr} == false");
                    }
                    "greater_than_or_equal" => {
                        if let Some(val) = &assertion.value {
                            let n = val.as_u64().unwrap_or(0);
                            let _ = writeln!(out, "      assert {call_expr} >= {n}");
                        }
                    }
                    "count_min" => {
                        if let Some(val) = &assertion.value {
                            let n = val.as_u64().unwrap_or(0);
                            let _ = writeln!(out, "      assert length({call_expr}) >= {n}");
                        }
                    }
                    "contains" => {
                        if let Some(val) = &assertion.value {
                            let elixir_val = json_to_elixir(val);
                            let _ = writeln!(out, "      assert String.contains?({call_expr}, {elixir_val})");
                        }
                    }
                    "is_error" => {
                        let _ = writeln!(out, "      assert_raise RuntimeError, fn -> {call_expr} end");
                    }
                    other_check => {
                        panic!("Elixir e2e generator: unsupported method_result check type: {other_check}");
                    }
                }
            } else {
                panic!("Elixir e2e generator: method_result assertion missing 'method' field");
            }
        }
        "matches_regex" => {
            if let Some(expected) = &assertion.value {
                let elixir_val = json_to_elixir(expected);
                let _ = writeln!(out, "      assert Regex.match?(~r/{elixir_val}/, {field_expr})");
            }
        }
        "not_error" => {
            // Already handled — the call would fail if it returned {:error, _}.
        }
        "error" => {
            // Handled at the test level.
        }
        other => {
            panic!("Elixir e2e generator: unsupported assertion type: {other}");
        }
    }
}

/// Build an Elixir call expression for a `method_result` assertion on a tree-sitter result.
/// Maps method names to the appropriate `module_path` function calls.
fn build_elixir_method_call(
    result_var: &str,
    method_name: &str,
    args: Option<&serde_json::Value>,
    module_path: &str,
) -> String {
    match method_name {
        "root_child_count" => format!("{module_path}.root_child_count({result_var})"),
        "has_error_nodes" => format!("{module_path}.tree_has_error_nodes({result_var})"),
        "error_count" | "tree_error_count" => format!("{module_path}.tree_error_count({result_var})"),
        "tree_to_sexp" => format!("{module_path}.tree_to_sexp({result_var})"),
        "contains_node_type" => {
            let node_type = args
                .and_then(|a| a.get("node_type"))
                .and_then(|v| v.as_str())
                .unwrap_or("");
            format!("{module_path}.tree_contains_node_type({result_var}, \"{node_type}\")")
        }
        "find_nodes_by_type" => {
            let node_type = args
                .and_then(|a| a.get("node_type"))
                .and_then(|v| v.as_str())
                .unwrap_or("");
            format!("{module_path}.find_nodes_by_type({result_var}, \"{node_type}\")")
        }
        "run_query" => {
            let query_source = args
                .and_then(|a| a.get("query_source"))
                .and_then(|v| v.as_str())
                .unwrap_or("");
            let language = args
                .and_then(|a| a.get("language"))
                .and_then(|v| v.as_str())
                .unwrap_or("");
            format!("{module_path}.run_query({result_var}, \"{language}\", \"{query_source}\", source)")
        }
        _ => format!("{module_path}.{method_name}({result_var})"),
    }
}

/// Convert a category name to an Elixir module-safe PascalCase name.
fn elixir_module_name(category: &str) -> String {
    use heck::ToUpperCamelCase;
    category.to_upper_camel_case()
}

/// Convert a `serde_json::Value` to an Elixir literal string.
fn json_to_elixir(value: &serde_json::Value) -> String {
    match value {
        serde_json::Value::String(s) => format!("\"{}\"", escape_elixir(s)),
        serde_json::Value::Bool(true) => "true".to_string(),
        serde_json::Value::Bool(false) => "false".to_string(),
        serde_json::Value::Number(n) => {
            // Elixir requires floats to have a decimal point and does not accept
            // `e+N` exponent notation. Strip the `+` and ensure there is a decimal
            // point before any `e` exponent marker (e.g. `1e-10` → `1.0e-10`).
            let s = n.to_string().replace("e+", "e");
            if s.contains('e') && !s.contains('.') {
                // Insert `.0` before the `e` so Elixir treats this as a float.
                s.replacen('e', ".0e", 1)
            } else {
                s
            }
        }
        serde_json::Value::Null => "nil".to_string(),
        serde_json::Value::Array(arr) => {
            let items: Vec<String> = arr.iter().map(json_to_elixir).collect();
            format!("[{}]", items.join(", "))
        }
        serde_json::Value::Object(map) => {
            let entries: Vec<String> = map
                .iter()
                .map(|(k, v)| format!("\"{}\" => {}", escape_elixir(k), json_to_elixir(v)))
                .collect();
            format!("%{{{}}}", entries.join(", "))
        }
    }
}

/// Build an Elixir visitor map and add setup line. Returns the visitor variable name.
fn build_elixir_visitor(setup_lines: &mut Vec<String>, visitor_spec: &crate::fixture::VisitorSpec) -> String {
    use std::fmt::Write as FmtWrite;
    let mut visitor_obj = String::new();
    let _ = writeln!(visitor_obj, "%{{");
    for (method_name, action) in &visitor_spec.callbacks {
        emit_elixir_visitor_method(&mut visitor_obj, method_name, action);
    }
    let _ = writeln!(visitor_obj, "    }}");

    setup_lines.push(format!("visitor = {visitor_obj}"));
    "visitor".to_string()
}

/// Emit an Elixir visitor method for a callback action.
fn emit_elixir_visitor_method(out: &mut String, method_name: &str, action: &CallbackAction) {
    use std::fmt::Write as FmtWrite;

    // Elixir uses atom keys and handle_ prefix
    let handle_method = format!("handle_{}", &method_name[6..]); // strip "visit_" prefix
    let params = match method_name {
        "visit_link" => "_ctx, _href, _text, _title",
        "visit_image" => "_ctx, _src, _alt, _title",
        "visit_heading" => "_ctx, _level, text, _id",
        "visit_code_block" => "_ctx, _lang, _code",
        "visit_code_inline"
        | "visit_strong"
        | "visit_emphasis"
        | "visit_strikethrough"
        | "visit_underline"
        | "visit_subscript"
        | "visit_superscript"
        | "visit_mark"
        | "visit_button"
        | "visit_summary"
        | "visit_figcaption"
        | "visit_definition_term"
        | "visit_definition_description" => "_ctx, _text",
        "visit_text" => "_ctx, _text",
        "visit_list_item" => "_ctx, _ordered, _marker, _text",
        "visit_blockquote" => "_ctx, _content, _depth",
        "visit_table_row" => "_ctx, _cells, _is_header",
        "visit_custom_element" => "_ctx, _tag_name, _html",
        "visit_form" => "_ctx, _action_url, _method",
        "visit_input" => "_ctx, _input_type, _name, _value",
        "visit_audio" | "visit_video" | "visit_iframe" => "_ctx, _src",
        "visit_details" => "_ctx, _is_open",
        "visit_element_end" | "visit_table_end" | "visit_definition_list_end" | "visit_figure_end" => "_ctx, _output",
        "visit_list_start" => "_ctx, _ordered",
        "visit_list_end" => "_ctx, _ordered, _output",
        _ => "_ctx",
    };

    let _ = writeln!(out, "      :{handle_method} => fn({params}) ->");
    match action {
        CallbackAction::Skip => {
            let _ = writeln!(out, "        :skip");
        }
        CallbackAction::Continue => {
            let _ = writeln!(out, "        :continue");
        }
        CallbackAction::PreserveHtml => {
            let _ = writeln!(out, "        :preserve_html");
        }
        CallbackAction::Custom { output } => {
            let escaped = escape_elixir(output);
            let _ = writeln!(out, "        {{:custom, \"{escaped}\"}}");
        }
        CallbackAction::CustomTemplate { template } => {
            // For template, use string interpolation in Elixir (but simplified without arg binding)
            let escaped = escape_elixir(template);
            let _ = writeln!(out, "        {{:custom, \"{escaped}\"}}");
        }
    }
    let _ = writeln!(out, "      end,");
}