# Nix-built Grafana Pyroscope continuous profiling server
# Builds v1.19.1 from forge mirror
# Uses stdenv + make (not buildGoModule) due to multi-module go.work workspace
# with local replace directives (./api, ./lidia)
# Built with dockerTools.buildLayeredImage for efficient layer caching
{ pkgs ? import <nixpkgs> { } }:

let
  version = "1.19.1";

  src = pkgs.fetchgit {
    url = "https://forge.ops.eblu.me/mirrors/pyroscope.git";
    rev = "v${version}";
    hash = "sha256-UPxGimkzXLFACqmAM1hNQIoNjN6OquVibwVmNvP00+s=";
  };

  # Build frontend assets via yarn + webpack (upstream uses Docker for this)
  # mkYarnPackage symlinks node_modules from the Nix store, but webpack's
  # CopyPlugin can't follow symlinks for glob patterns. We dereference the
  # @grafana/ui icons directory before running the build.
  ui = pkgs.mkYarnPackage {
    inherit version src;
    pname = "pyroscope-ui";

    buildPhase = ''
      runHook preBuild
      export HOME=$TMPDIR
      cd deps/grafana-pyroscope

      # mkYarnPackage symlinks node_modules into the Nix store (read-only).
      # Webpack CopyPlugin can't glob through these symlinks to find
      # @grafana/ui icons. Pre-copy them to the output location and patch
      # webpack to skip the CopyPlugin entry for icons.
      mkdir -p public/build/grafana/build/img
      cp -rL ../../node_modules/@grafana/ui/dist/public/img/icons \
        public/build/grafana/build/img/

      # Rewrite the CopyPlugin icons path to point at our pre-copied location
      # instead of the symlinked node_modules path that webpack can't glob
      sed -i "s|from: 'node_modules/@grafana/ui/dist/public/img/icons'|from: 'public/build/grafana/build/img/icons'|" \
        scripts/webpack/webpack.common.js

      yarn --offline build
      runHook postBuild
    '';

    installPhase = ''
      runHook preInstall
      mkdir -p $out
      cp -r public/build/* $out/
      runHook postInstall
    '';

    distPhase = "true";
  };

  # Pre-fetch Go modules for all go.mod files in the workspace (fixed-output derivation)
  goModules = pkgs.stdenv.mkDerivation {
    pname = "pyroscope-go-modules";
    inherit src version;

    nativeBuildInputs = with pkgs; [ go git cacert ];

    buildPhase = ''
      export GOPATH=$TMPDIR/go
      export GOFLAGS=-modcacherw
      # Download modules for all workspace members
      go mod download
      cd api && go mod download && cd ..
      cd lidia && go mod download && cd ..
    '';

    installPhase = ''
      cp -r $TMPDIR/go/pkg/mod $out
    '';

    # Disable fixup: patchelf and patchShebangs modify downloaded Go toolchain
    # binaries, which makes the fixed-output derivation reference store paths
    dontFixup = true;

    outputHashMode = "recursive";
    outputHash = "sha256-RCWuqz1XaDrS7+GqL/9v7LNA14M4/ohWEtPeTMDkJFc=";
    outputHashAlgo = "sha256";
  };

  pyroscope = pkgs.stdenv.mkDerivation {
    inherit src version;
    pname = "pyroscope";

    nativeBuildInputs = with pkgs; [
      go
      git
      gnumake
      cacert
    ];

    buildPhase = ''
      runHook preBuild

      export HOME=$TMPDIR
      export GOPATH=$TMPDIR/go
      export GOFLAGS=-modcacherw

      # Populate module cache from pre-fetched modules
      mkdir -p $GOPATH/pkg
      cp -r ${goModules} $GOPATH/pkg/mod
      chmod -R u+w $GOPATH/pkg/mod

      # Copy pre-built frontend assets
      mkdir -p public/build
      cp -r ${ui}/* public/build/

      # Build Go binary with embedded frontend assets
      # Skip the Makefile's frontend/build target (uses Docker) and
      # invoke go/bin directly with EMBEDASSETS set
      # CGO_ENABLED=0 for static binary (matches upstream)
      CGO_ENABLED=0 \
        EMBEDASSETS=embedassets \
        IMAGE_TAG=v${version} \
        make go/bin

      runHook postBuild
    '';

    installPhase = ''
      runHook preInstall
      mkdir -p $out/bin
      cp pyroscope $out/bin/pyroscope
      runHook postInstall
    '';

    meta = with pkgs.lib; {
      description = "Grafana Pyroscope continuous profiling platform";
      homepage = "https://grafana.com/docs/pyroscope/";
      license = licenses.agpl3Only;
      mainProgram = "pyroscope";
    };
  };
in

pkgs.dockerTools.buildLayeredImage {
  name = "blumeops/pyroscope";
  contents = [
    pyroscope
    pkgs.cacert
    pkgs.tzdata
  ];

  config = {
    Entrypoint = [ "${pyroscope}/bin/pyroscope" ];
    Cmd = [ "-config.path=/etc/pyroscope/config.yaml" ];
    Env = [
      "SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
      "TZDIR=${pkgs.tzdata}/share/zoneinfo"
    ];
    ExposedPorts = {
      "4040/tcp" = { };
    };
    User = "65534";
  };
}