{
    inputs = {
        ihp.url = "github:digitallyinduced/ihp/v1.5";
        nixpkgs.follows = "ihp/nixpkgs";
        nixpkgs-nixos.follows = "ihp/nixpkgs-nixos";
        flake-parts.follows = "ihp/flake-parts";
        devenv.follows = "ihp/devenv";
        systems.follows = "ihp/systems";
        devenv-root = {
            url = "file+file:///dev/null";
            flake = false;
        };
    };

    outputs = inputs@{ self, nixpkgs, nixpkgs-nixos, ihp, flake-parts, systems, ... }:
        flake-parts.lib.mkFlake { inherit inputs; } {

            systems = import systems;
            imports = [ ihp.flakeModules.default ];

            perSystem = { pkgs, config, lib, ... }: {
                ihp = {
                    appName = "inter-hub";
                    enable = true;
                    projectPath = ./.;
                    packages = with pkgs; [
                        tailwindcss
                    ];
                    haskellPackages = p: with p; [
                        # Haskell dependencies go here
                        p.ihp
                        base
                        wai
                        text
                        # ihp-mail           # Email support: https://ihp.digitallyinduced.com/Guide/mail.html
                        # ihp-datasync       # Real-time DataSync
                        # ihp-job-dashboard  # Job dashboard UI
                        # ihp-typed-sql      # Type-safe SQL queries
                        # ihp-pglistener     # PostgreSQL LISTEN/NOTIFY
                        # Phase 5: Anthropic API calls
                        http-conduit
                        aeson
                        string-conversions
                        # Phase 9: External API, crypto, SDK generation
                        cryptohash-sha256
                        base16-bytestring
                        random-bytestring
                        yaml
                        network-uri
                    ];
                    devHaskellPackages = p: with p; [
                        cabal-install
                        hlint
                        hspec
                        ihp-hspec
                    ];

                    # Hoogle documentation server — disabled to save ~400 MB on constrained host
                    withHoogle = false;

                    # Disable relation type machinery for faster compilation
                    # relationSupport = false;

                    # Skip tests/haddock for specific packages to speed up builds
                    # dontCheckPackages = [ "my-package" ];
                    # doJailbreakPackages = [ "my-package" ];
                    # dontHaddockPackages = [ "my-package" ];

                    # Production build tuning
                    # optimizationLevel = "2"; # Default: "1", use "2" for more optimized production binaries
                    # rtsFlags = "-A96m -N"; # GHC runtime flags for compiled binaries

                    # Mount additional directories under /static/ in production builds
                    # static.extraDirs = {
                    #     # Frontend = self.packages.${system}.frontend;
                    # };
                    # static.makeBundling = true; # Set false if not using Makefile for CSS/JS bundling
                };

                # OCI container image for Kubernetes deployment (Railiance01).
                # Build: nix build .#docker
                # Push:  skopeo copy docker-archive:result docker://92.205.130.254:32166/coulomb/inter-hub:SHA
                # Uses IHP's built-in unoptimized image; binary is /bin/RunProdServer.
                packages.docker = config.packages.unoptimized-docker-image;

                # Custom configuration that will start with `devenv up`
                devenv.shells.default = {
                    # Start Mailhog on local development to catch outgoing emails
                    # services.mailhog.enable = true;

                    # PostgreSQL extensions
                    # services.postgres.extensions = extensions: [ extensions.postgis ];

                    # GHC 9.10.3 crash fix: Generated.Types imports 119 modules, exceeding
                    # the ~287 MB interface-file binary-deserialization limit.
                    #
                    # pkgs is built from `import nixpkgs { overlays = devenv.shells.default.overlays; }`.
                    # IHP adds ihp.overlays.default to this list, which sets
                    # pkgs.ghc = haskellPackages.override { overrides = ihpOverrides }.
                    # We extend pkgs.ghc with a mkDerivation override (lib.mkAfter ensures
                    # we run after IHP's overlay, so prev.ghc is already IHP's package set).
                    # When pname == "inter-hub-models", postUnpack replaces the monolithic
                    # Types.hs with a thin re-export wrapper and ensures TypesPart1/TypesPart2
                    # are present and listed in the cabal.
                    overlays = lib.mkAfter [
                        (final: prev: {
                            ghc = prev.ghc.extend (hfinal: hprev: {
                                mkDerivation = args:
                                    let drv = hprev.mkDerivation args;
                                    in if (args.pname or "") == "inter-hub-models"
                                       then drv.overrideAttrs (old: {
                                           # Splits the monolithic Generated.Types (119 imports, ~287 MB
                                           # interface-file overflow in GHC 9.10.3) into two halves.
                                           # All awk/printf: no external file deps, no git-tracking required.
                                           postUnpack = (old.postUnpack or "") + ''
                                               _types="$sourceRoot/build/Generated/Types.hs"

                                               # TypesPart1: first half of modules
                                               awk 'BEGIN{n=0} /^import Generated\./{n++; mods[n]=$2} END{
                                                   half=int(n/2)+1
                                                   print "-- Split: GHC 9.10.3 interface-file overflow workaround."
                                                   print "module Generated.TypesPart1 ("
                                                   for(i=1;i<=half;i++) {
                                                       if(i<half) print "    module " mods[i] ","
                                                       else        print "    module " mods[i]
                                                   }
                                                   print "    ) where"
                                                   for(i=1;i<=half;i++) print "import " mods[i]
                                               }' "$_types" > "$sourceRoot/build/Generated/TypesPart1.hs"

                                               # TypesPart2: second half of modules
                                               awk 'BEGIN{n=0} /^import Generated\./{n++; mods[n]=$2} END{
                                                   half=int(n/2)+1
                                                   print "-- Split: GHC 9.10.3 interface-file overflow workaround."
                                                   print "module Generated.TypesPart2 ("
                                                   for(i=half+1;i<=n;i++) {
                                                       if(i<n) print "    module " mods[i] ","
                                                       else    print "    module " mods[i]
                                                   }
                                                   print "    ) where"
                                                   for(i=half+1;i<=n;i++) print "import " mods[i]
                                               }' "$_types" > "$sourceRoot/build/Generated/TypesPart2.hs"

                                               # Thin wrapper replaces the monolithic Types.hs
                                               printf '%s\n' \
                                                   '-- Split wrapper: GHC 9.10.3 interface-file overflow workaround.' \
                                                   'module Generated.Types (' \
                                                   '    module Generated.TypesPart1,' \
                                                   '    module Generated.TypesPart2' \
                                                   '    ) where' \
                                                   'import Generated.TypesPart1' \
                                                   'import Generated.TypesPart2' \
                                                   > "$_types"

                                               # Add TypesPart1/TypesPart2 to cabal exposed-modules and add
                                               # ghc-options: -O0 to keep interface file sizes below the
                                               # GHC 9.10.3 binary-deserialisation limit (~287 MB).
                                               # -O0 strips unfoldings/specialisations from .hi files,
                                               # reducing them by ~10x so TypesPart*.hi stays well under the limit.
                                               _cabal=$(ls "$sourceRoot"/*.cabal | head -1)
                                               if ! grep -q 'Generated\.TypesPart1' "$_cabal"; then
                                                   awk '/^    exposed-modules:/{
                                                       print "    ghc-options: -O0"
                                                       print
                                                       next
                                                   } /Generated\.LearningInsightInclude/{
                                                       print
                                                       print "        Generated.TypesPart1"
                                                       print "        Generated.TypesPart2"
                                                       next
                                                   }{print}' "$_cabal" > "$_cabal.new"
                                                   mv "$_cabal.new" "$_cabal"
                                               fi
                                           '';
                                       })
                                       else drv;
                            });
                        })
                    ];

                    # Resource limits for constrained host (2 CPU, ~3.8 GiB RAM).
                    # -A32m: smaller minor heap (reduces GC pressure).
                    # -M2g: hard heap ceiling (prevents OOM on large compiles).
                    # Note: -N1 is intentionally omitted — it requires -threaded and
                    # would break build-generated-code and similar tools.
                    # GHC parallel module compilation is capped via -j1 in .ghci.
                    env.GHCRTS = "-A32m -M2g";

                    # Custom processes that don't appear in https://devenv.sh/reference/options/
                    processes = {
                        tailwind.exec = "tailwindcss -c tailwind/tailwind.config.js -i ./tailwind/app.css -o static/app.css --watch=always";
                    };
                };
            };

            # Adding the new NixOS configuration for "production"
            # See https://ihp.digitallyinduced.com/Guide/deployment.html#deploying-with-deploytonixos for more info
            # Used to deploy the IHP application
            flake.nixosConfigurations."production" = import ./Config/nix/hosts/production/host.nix { inherit inputs; };
        };

    # The following configuration speeds up build times by using the devenv, cachix and digitallyinduced binary caches
    # You can add your own cachix cache here to speed up builds. For that uncomment the following lines and replace `CHANGE-ME` with your cachix cache name
    nixConfig = {
        extra-substituters = [
            "https://devenv.cachix.org"
            "https://cachix.cachix.org"
            "https://digitallyinduced.cachix.org"
            # "https://CHANGE-ME.cachix.org"
        ];
        extra-trusted-public-keys = [
            "devenv.cachix.org-1:w1cLUi8dv3hnoSPGAuibQv+f9TZLr6cv/Hm9XgU50cw="
            "cachix.cachix.org-1:eWNHQldwUO7G2VkjpnjDbWwy4KQ/HNxht7H4SSoMckM="
            "digitallyinduced.cachix.org-1:y+wQvrnxQ+PdEsCt91rmvv39qRCYzEgGQaldK26hCKE="
            # "CHANGE-ME.cachix.org-1:CHANGE-ME-PUBLIC-KEY"
        ];
    };
}