# Shell snippets prepended to mkLogosModule / mkLogosModuleTests preConfigure.
{ lib }:

let
  # accounts_module -> AccountsModuleImpl
  defaultImplClassFromName = moduleName:
    let
      parts = lib.filter (s: s != "") (lib.splitString "_" moduleName);
      cap = s:
        if s == "" then ""
        else lib.toUpper (lib.substring 0 1 s) + lib.substring 1 (builtins.stringLength s - 1) s;
    in
      lib.concatStrings (map cap parts) + "Impl";

  # Copy resolved external library outputs into ./lib for CMake EXTERNAL_LIBS / includes
  copyExternalLibsToLib = externalLibs:
    let
      names = builtins.attrNames externalLibs;
      one = name:
        let
          v = externalLibs.${name};
        in
          if v == null then ""
          else ''
            if [ -d "${v}/lib" ]; then
              cp -f "${v}"/lib/* lib/ 2>/dev/null || true
            fi
            # Windows ships a shared library's runtime half in bin/ (CMake's
            # RUNTIME destination). Mirror of the staging in
            # logos-plugin-qt/lib/buildPlugin.nix -- see the longer note there
            # for why only this library's own files are taken, not all of bin/.
            if [ -d "${v}/bin" ]; then
              for f in "${v}"/bin/lib${name}.dll "${v}"/bin/${name}.dll; do
                [ -f "$f" ] && cp -fL "$f" lib/ 2>/dev/null || true
              done
            fi
            if [ -d "${v}/include" ]; then
              cp -f "${v}"/include/*.h lib/ 2>/dev/null || true
            fi
          '';
    in
      if names == [] then ""
      else ''
        mkdir -p lib
        ${lib.concatMapStringsSep "\n" one names}
      '';

  # macOS: fix install_name on copied dylibs so tests/runtime resolve via RPATH
  fixupDarwinDylibs = ''
    if [ "$(uname -s)" = Darwin ]; then
      for f in lib/*.dylib; do
        [ -f "$f" ] || continue
        bn=$(basename "$f")
        install_name_tool -id "@rpath/$bn" "$f" 2>/dev/null || true
      done
    fi
  '';

  universalCodegen = config:
    let
      cg = config.codegen or {};
      implClass = cg.impl_class or (defaultImplClassFromName config.name);
      ihRaw = cg.impl_header or "${config.name}_impl.h";
      fromPath =
        if lib.hasInfix "/" ihRaw then ihRaw else "src/${ihRaw}";
      # Include string embedded in generated glue (basename when path is qualified)
      implHeaderInclude =
        if lib.hasInfix "/" ihRaw then builtins.baseNameOf ihRaw else ihRaw;
    in
      ''
        echo "logos-module-builder: generating universal module glue (${config.name})..."
        # Universal modules are header-first cdylibs: same Qt-free mechanism as
        # the `cdylib` interface, but the LIDL contract is DERIVED from the impl
        # header instead of hand-committed. The author still writes only the
        # impl class (deriving LogosModuleContext); the module's own TUs stay
        # Qt-free and its outbound modules().<dep> calls go through the lp_* C
        # ABI (apiStyle=lp). Qt is confined to the generated uniform glue.
        #
        # 1. Derive the LIDL contract from the impl header. Doubles as the
        #    published events sidecar consumed by dependents' typed-event codegen.
        logos-cpp-generator --header-to-lidl "${fromPath}" \
          --impl-class ${implClass} \
          --metadata metadata.json \
          -o ./generated_code/${config.name}.lidl
        # 2. The uniform Qt-plugin glue over the common module-impl C ABI
        #    (logos_host loads it unchanged — load ABI preserved).
        logos-qt-host-generator --lidl ./generated_code/${config.name}.lidl \
          --backend cdylib \
          ${lib.optionalString ((config.concurrency or "single") == "multi") "--concurrency multi"} \
          --output-dir ./generated_code
        # 3. The Qt-FREE C-ABI export wrapper (+ typed event emitters) around
        #    the hand-written impl class.
        # No --concurrency here: the C++ cdylib's logos_module_dispatch is
        # already safe to call concurrently (no lock across the handler), so the
        # multi worker pool lives entirely in the Qt glue above. The author owns
        # thread-safety of the impl's methods under concurrency:"multi".
        logos-cpp-generator --lidl ./generated_code/${config.name}.lidl \
          --backend cdylib \
          --impl-class ${implClass} \
          --impl-header ${implHeaderInclude} \
          --output-dir ./generated_code
      '';

  # Cdylib authoring: the module is (or wraps) a cdylib exporting the common
  # module-impl C ABI (logos_module_impl.h in logos-protocol). The generator
  # emits only the uniform Qt-plugin glue from the LIDL contract; the C
  # exports come from the module's own language backend — the C++ SDK's
  # `--from-header --backend cdylib` wrapper or the Rust SDK's
  # `lidl-gen --provider`. The glue is identical either way.
  cdylibCodegen = config:
    let
      cg = config.codegen or {};
      # A rust-first module (codegen.rust.trait) derives its .lidl from the trait;
      # the builder stages it at generated_code/<name>.lidl (mkLogosModule's
      # lidlStaging), so no codegen.lidl is needed. Otherwise it's the committed
      # contract named by codegen.lidl.
      lidlFile =
        if ((cg.rust or {}).trait or null) != null
        then "generated_code/${config.name}.lidl"
        else (cg.lidl or (throw "cdylib interface requires codegen.lidl in metadata.json"));
      # Contract-first C++ flavor: when codegen names an impl_class, the
      # generator ALSO emits the C-ABI export wrapper (+ typed events) around
      # that hand-written Qt-free class. Without it (e.g. Rust modules whose
      # exports come from lidl-gen --provider) only the uniform glue is
      # generated.
      implClass = cg.impl_class or null;
      implHeaderRaw = cg.impl_header or "${config.name}_impl.h";
      implHeader =
        if lib.hasInfix "/" implHeaderRaw
        then builtins.baseNameOf implHeaderRaw
        else implHeaderRaw;
      implFlags =
        if implClass == null then ""
        else "--impl-class ${implClass} --impl-header ${implHeader}";
    in
      ''
        echo "logos-module-builder: generating cdylib Qt glue (${config.name})..."
        logos-qt-host-generator --lidl "${lidlFile}" \
          --backend cdylib \
          ${lib.optionalString ((config.concurrency or "single") == "multi") "--concurrency multi"} \
          --output-dir ./generated_code
        ${lib.optionalString (implClass != null) ''
          # Contract-first C++ flavor: the Qt-FREE C-ABI export wrapper
          # (+ typed event emitters) around the hand-written impl class.
          # No --concurrency: the C++ cdylib dispatch is already concurrency-safe;
          # the multi worker pool lives in the Qt glue (logos-qt-generator above).
          logos-cpp-generator --lidl "${lidlFile}" \
            --backend cdylib \
            ${implFlags} \
            --output-dir ./generated_code
        ''}
      '';

  # UI plugin backends (type=ui_qml + interface=universal): the USER
  # writes the .rep (the view contract) and the *Backend class (deriving
  # <RepClass>SimpleSource + LogosUiPluginContext); the view generator emits
  # only the *Interface.h and the *Plugin glue that wires the (Qt-typed)
  # LogosModules aggregate into the backend on initLogos.
  #
  # The binary is logos-VIEW-generator (logos-view-module), not
  # logos-qt-generator (logos-qt-sdk). Both shipped the same emitter for a
  # while and they rotted apart: logos-qt-sdk#38 added the module teardown
  # hook to the copy this line used to call, and the other copy never got it.
  #
  # That divergence was invisible, and would have become permanent the moment
  # this line was repointed without reconciling first: ui-host reaches
  # aboutToUnload() BY NAME through the meta-object, so a generated plugin
  # class that does not declare it simply has no such meta-method --
  # QMetaObject::invokeMethod returns false and the host moves on, which is
  # indistinguishable from a view answering "Synchronous, nothing to wait for".
  # No build, load or call fails; every view just silently loses its chance to
  # finish. logos-view-module's `ui-plugin-metaobject` check now compiles the
  # emitted plugin and drives that handshake through QPluginLoader, so the
  # regression cannot recur silently in the new home.
  #
  # The generator lives with the LogosView*.in templates its output is compiled
  # against and with logos_ui_plugin_context.h, which its output calls into --
  # one authoring surface, one repo, matching how logos-plugin-qt owns the
  # cdylib Qt-plugin glue.
  #
  # `--backend ui` is spelled explicitly even though it is that binary's
  # default: it keeps the call site self-describing, and logos-view-generator
  # REFUSES an unrecognised --backend rather than silently defaulting.
  uiCodegen = config:
    let
      cg = config.codegen or {};
      repFile = cg.rep or "src/${config.name}.rep";
      backendFlags =
        lib.optionalString (cg ? backend_class) " --backend-class ${cg.backend_class}"
        + lib.optionalString (cg ? backend_header) " --backend-header ${cg.backend_header}";
    in
      ''
        echo "logos-module-builder: generating ui plugin glue (${config.name})..."
        logos-view-generator --backend ui \
          --metadata metadata.json \
          --rep "${repFile}"${backendFlags} \
          --output-dir ./generated_code
      '';

  autoCodegen = config:
    if config.interface == "universal" && (config.type or "core") == "ui_qml"
      then uiCodegen config
    else if config.interface == "universal" then universalCodegen config
    else if config.interface == "cdylib" then cdylibCodegen config
    # `interface: "provider"` (LOGOS_METHOD dispatch via
    # `logos-cpp-generator --provider-header`) was removed. Throw rather than
    # falling through to the `else ""` no-op below: an unrecognised interface
    # silently generates NO glue, so the module would build green and then be
    # un-callable from every consumer.
    else if config.interface == "provider" then
      throw ("logos-module-builder: module '${config.name}' declares the removed "
             + "interface \"provider\". Use interface \"universal\": write a plain "
             + "src/${config.name}_impl.h and the contract is derived from it.")
    # `legacy` — the default when metadata.json omits `interface` — generates no
    # glue at all. For a CONSUMER that is correct and normal: a ui_qml view
    # plugin is not loaded by liblogos, and a fixture that only builds tests has
    # nothing to expose. For a module that ships a plugin liblogos loads and
    # other modules call, it is the silent form of exactly what the `provider`
    # branch above throws for — the module builds green and is un-callable from
    # every consumer.
    #
    # `main` is what separates the two, and it is the only field that does:
    # `type` alone cannot, because the core fixtures that legitimately generate
    # nothing are core too. A provider ships a plugin, so it names one.
    else if (config.type or "core") == "core" && (config.main or null) != null then
      throw ("logos-module-builder: module '${config.name}' is a core module "
             + "shipping a plugin (main: ${config.main}) but declares no "
             + "`interface`, so NO glue would be generated and every call into "
             + "it would fail at runtime rather than at build time. Use "
             + "interface \"universal\" (write a plain src/${config.name}_impl.h "
             + "and the contract is derived from it) or \"cdylib\" (bring your "
             + "own C ABI plus codegen.lidl).")
    else "";

  # Order: optional ext copy -> optional darwin fixup -> codegen -> user hook
  # Note: mkLogosModule main builds already copy externals in logos-plugin-qt buildPlugin
  # (externalLibCopies). Use copyExternals=true only for contexts without that (e.g. unit tests).
  # Stamp the logos-protocol semver the module is being built against into
  # the metadata.json the plugin embeds (Q_PLUGIN_METADATA). One number
  # governs Logos load/call compatibility (same MAJOR <=> compatible);
  # liblogos reads it pre-load. Runs before cmake/moc so the embedded copy
  # carries the field; modules built by older builders simply lack it and
  # load permissively ("legacy").
  stampProtocolVersion = protocolVersion:
    if protocolVersion == null then "" else ''
      if [ -f ./metadata.json ]; then
        jq '. + {logos_protocol_version: "${protocolVersion}"}' ./metadata.json           > ./metadata.json.lp-stamp && mv ./metadata.json.lp-stamp ./metadata.json
        echo "Stamped logos_protocol_version=${protocolVersion} into metadata.json"
      fi
    '';

  # preCodegen runs AFTER the protocol-version stamp / external copy / darwin fix
  # but BEFORE codegen — used to stage a builder-derived .lidl (rust-first) into
  # the tree where cdylibCodegen will read codegen.lidl.
  compose = { config, externalLibs, userPre, fixDarwin ? false, copyExternals ? false, protocolVersion ? null, preCodegen ? "" }:
    let
      stamp = stampProtocolVersion protocolVersion;
      copy = if copyExternals then copyExternalLibsToLib externalLibs else "";
      codegen = autoCodegen config;
      fix = if fixDarwin then fixupDarwinDylibs else "";
    in
      stamp + copy + fix + preCodegen + codegen + userPre;

in {
  inherit defaultImplClassFromName copyExternalLibsToLib fixupDarwinDylibs universalCodegen uiCodegen autoCodegen compose stampProtocolVersion;
}