# This file originates from node2nix

{stdenv, nodejs, python2, utillinux, runCommand, writeTextFile}:

let
  python = if nodejs ? python then nodejs.python else python2;

  # Create a tar wrapper that filters all the 'Ignoring unknown extended header keyword' noise
  tarWrapper = runCommand "tarWrapper" {} ''
    mkdir -p $out/bin

    cat > $out/bin/tar <<EOF
    #! ${stdenv.shell} -e
    $(type -p tar) "\$@" --warning=no-unknown-keyword
    EOF

    chmod +x $out/bin/tar
  '';

  # Function that generates a TGZ file from a NPM project
  buildNodeSourceDist =
    { name, version, src, ... }:

    stdenv.mkDerivation {
      name = "node-tarball-${name}-${version}";
      inherit src;
      buildInputs = [ nodejs ];
      buildPhase = ''
        export HOME=$TMPDIR
        tgzFile=$(npm pack)
      '';
      installPhase = ''
        mkdir -p $out/tarballs
        mv $tgzFile $out/tarballs
        mkdir -p $out/nix-support
        echo "file source-dist $out/tarballs/$tgzFile" >> $out/nix-support/hydra-build-products
      '';
    };

  includeDependencies = {dependencies}:
    stdenv.lib.optionalString (dependencies != [])
      (stdenv.lib.concatMapStrings (dependency:
        ''
          # Bundle the dependencies of the package
          mkdir -p node_modules
          cd node_modules

          # Only include dependencies if they don't exist. They may also be bundled in the package.
          if [ ! -e "${dependency.name}" ]
          then
              ${composePackage dependency}
          fi

          cd ..
        ''
      ) dependencies);

  # Recursively composes the dependencies of a package
  composePackage = { name, packageName, src, dependencies ? [], ... }@args:
    ''
      DIR=$(pwd)
      cd $TMPDIR

      unpackFile ${src}

      # Make the base dir in which the target dependency resides first
      mkdir -p "$(dirname "$DIR/${packageName}")"

      if [ -f "${src}" ]
      then
          # Figure out what directory has been unpacked
          packageDir="$(find . -maxdepth 1 -type d | tail -1)"

          # Restore write permissions to make building work
          find "$packageDir" -type d -print0 | xargs -0 chmod u+x
          chmod -R u+w "$packageDir"

          # Move the extracted tarball into the output folder
          mv "$packageDir" "$DIR/${packageName}"
      elif [ -d "${src}" ]
      then
          # Get a stripped name (without hash) of the source directory.
          # On old nixpkgs it's already set internally.
          if [ -z "$strippedName" ]
          then
              strippedName="$(stripHash ${src})"
          fi

          # Restore write permissions to make building work
          chmod -R u+w "$strippedName"

          # Move the extracted directory into the output folder
          mv "$strippedName" "$DIR/${packageName}"
      fi

      # Unset the stripped name to not confuse the next unpack step
      unset strippedName

      # Include the dependencies of the package
      cd "$DIR/${packageName}"
      ${includeDependencies { inherit dependencies; }}
      cd ..
      ${stdenv.lib.optionalString (builtins.substring 0 1 packageName == "@") "cd .."}
    '';

  pinpointDependencies = {dependencies, production}:
    let
      pinpointDependenciesFromPackageJSON = writeTextFile {
        name = "pinpointDependencies.js";
        text = ''
          var fs = require('fs');
          var path = require('path');
          
          function resolveDependencyVersion(location, name) {
              if(location == process.env['NIX_STORE']) {
                  return null;
              } else {
                  var dependencyPackageJSON = path.join(location, "node_modules", name, "package.json");
                  
                  if(fs.existsSync(dependencyPackageJSON)) {
                      var dependencyPackageObj = JSON.parse(fs.readFileSync(dependencyPackageJSON));
                      
                      if(dependencyPackageObj.name == name) {
                          return dependencyPackageObj.version;
                      }
                  } else {
                      return resolveDependencyVersion(path.resolve(location, ".."), name);
                  }
              }
          }
          
          function replaceDependencies(dependencies) {
              if(typeof dependencies == "object" && dependencies !== null) {
                  for(var dependency in dependencies) {
                      var resolvedVersion = resolveDependencyVersion(process.cwd(), dependency);
                      
                      if(resolvedVersion === null) {
                          process.stderr.write("WARNING: cannot pinpoint dependency: "+dependency+", context: "+process.cwd()+"\n");
                      } else {
                          dependencies[dependency] = resolvedVersion;
                      }
                  }
              }
          }
          
          /* Read the package.json configuration */
          var packageObj = JSON.parse(fs.readFileSync('./package.json'));
          
          /* Pinpoint all dependencies */
          replaceDependencies(packageObj.dependencies);
          if(process.argv[2] == "development") {
              replaceDependencies(packageObj.devDependencies);
          }
          replaceDependencies(packageObj.optionalDependencies);
          
          /* Write the fixed package.json file */
          fs.writeFileSync("package.json", JSON.stringify(packageObj, null, 2));
        '';
      };
    in
    ''
      node ${pinpointDependenciesFromPackageJSON} ${if production then "production" else "development"}
      
      ${stdenv.lib.optionalString (dependencies != [])
        ''
          if [ -d node_modules ]
          then
              cd node_modules
              ${stdenv.lib.concatMapStrings (dependency: pinpointDependenciesOfPackage dependency) dependencies}
              cd ..
          fi
        ''}
    '';
  
  # Recursively traverses all dependencies of a package and pinpoints all
  # dependencies in the package.json file to the versions that are actually
  # being used.
  
  pinpointDependenciesOfPackage = { packageName, dependencies ? [], production ? true, ... }@args:
    ''
      if [ -d "${packageName}" ]
      then
          cd "${packageName}"
          ${pinpointDependencies { inherit dependencies production; }}
          cd ..
          ${stdenv.lib.optionalString (builtins.substring 0 1 packageName == "@") "cd .."}
      fi
    '';

  # Extract the Node.js source code which is used to compile packages with
  # native bindings
  nodeSources = runCommand "node-sources" {} ''
    tar --no-same-owner --no-same-permissions -xf ${nodejs.src}
    mv node-* $out
  '';

  # Builds and composes an NPM package including all its dependencies
  buildNodePackage = { name, packageName, version, dependencies ? [], production ? true, npmFlags ? "", dontNpmInstall ? false, preRebuild ? "", ... }@args:

    stdenv.lib.makeOverridable stdenv.mkDerivation (builtins.removeAttrs args [ "dependencies" ] // {
      name = "node-${name}-${version}";
      buildInputs = [ tarWrapper python nodejs ] ++ stdenv.lib.optional (stdenv.isLinux) utillinux ++ args.buildInputs or [];
      dontStrip = args.dontStrip or true; # Striping may fail a build for some package deployments

      inherit dontNpmInstall preRebuild;

      unpackPhase = args.unpackPhase or "true";

      buildPhase = args.buildPhase or "true";

      compositionScript = composePackage args;
      pinpointDependenciesScript = pinpointDependenciesOfPackage args;
      
      passAsFile = [ "compositionScript" "pinpointDependenciesScript" ];

      installPhase = args.installPhase or ''
        # Create and enter a root node_modules/ folder
        mkdir -p $out/lib/node_modules
        cd $out/lib/node_modules

        # Compose the package and all its dependencies
        source $compositionScriptPath
        
        # Pinpoint the versions of all dependencies to the ones that are actually being used
        echo "pinpointing versions of dependencies..."
        source $pinpointDependenciesScriptPath

        # Patch the shebangs of the bundled modules to prevent them from
        # calling executables outside the Nix store as much as possible
        patchShebangs .

        # Deploy the Node.js package by running npm install. Since the
        # dependencies have been provided already by ourselves, it should not
        # attempt to install them again, which is good, because we want to make
        # it Nix's responsibility. If it needs to install any dependencies
        # anyway (e.g. because the dependency parameters are
        # incomplete/incorrect), it fails.
        #
        # The other responsibilities of NPM are kept -- version checks, build
        # steps, postprocessing etc.

        export HOME=$TMPDIR
        cd "${packageName}"
        runHook preRebuild
        npm --registry http://www.example.com --nodedir=${nodeSources} ${npmFlags} ${stdenv.lib.optionalString production "--production"} rebuild

        if [ "$dontNpmInstall" != "1" ]
        then
            # NPM tries to download packages even when they already exist if npm-shrinkwrap is used.
            rm -f npm-shrinkwrap.json

            npm --registry http://www.example.com --nodedir=${nodeSources} ${npmFlags} ${stdenv.lib.optionalString production "--production"} install
        fi

        # Create symlink to the deployed executable folder, if applicable
        if [ -d "$out/lib/node_modules/.bin" ]
        then
            ln -s $out/lib/node_modules/.bin $out/bin
        fi

        # Create symlinks to the deployed manual page folders, if applicable
        if [ -d "$out/lib/node_modules/${packageName}/man" ]
        then
            mkdir -p $out/share
            for dir in "$out/lib/node_modules/${packageName}/man/"*
            do
                mkdir -p $out/share/man/$(basename "$dir")
                for page in "$dir"/*
                do
                    ln -s $page $out/share/man/$(basename "$dir")
                done
            done
        fi

        # Run post install hook, if provided
        runHook postInstall
      '';
    });

  # Builds a development shell
  buildNodeShell = { name, packageName, version, src, dependencies ? [], production ? true, npmFlags ? "", dontNpmInstall ? false, ... }@args:
    let
      nodeDependencies = stdenv.mkDerivation {
        name = "node-dependencies-${name}-${version}";

        buildInputs = [ tarWrapper python nodejs ] ++ stdenv.lib.optional (stdenv.isLinux) utillinux ++ args.buildInputs or [];

        includeScript = includeDependencies { inherit dependencies; };
        pinpointDependenciesScript = pinpointDependenciesOfPackage args;
        
        passAsFile = [ "includeScript" "pinpointDependenciesScript" ];

        buildCommand = ''
          mkdir -p $out/lib
          cd $out/lib
          source $includeScriptPath
          
          # Pinpoint the versions of all dependencies to the ones that are actually being used
          echo "pinpointing versions of dependencies..."
          source $pinpointDependenciesScriptPath

          # Create fake package.json to make the npm commands work properly
          cat > package.json <<EOF
          {
              "name": "${packageName}",
              "version": "${version}"
          }
          EOF

          # Patch the shebangs of the bundled modules to prevent them from
          # calling executables outside the Nix store as much as possible
          patchShebangs .

          export HOME=$PWD
          npm --registry http://www.example.com --nodedir=${nodeSources} ${npmFlags} ${stdenv.lib.optionalString production "--production"} rebuild

          ${stdenv.lib.optionalString (!dontNpmInstall) ''
            # NPM tries to download packages even when they already exist if npm-shrinkwrap is used.
            rm -f npm-shrinkwrap.json

            npm --registry http://www.example.com --nodedir=${nodeSources} ${npmFlags} ${stdenv.lib.optionalString production "--production"} install
          ''}

          ln -s $out/lib/node_modules/.bin $out/bin
        '';
      };
    in
    stdenv.lib.makeOverridable stdenv.mkDerivation {
      name = "node-shell-${name}-${version}";

      buildInputs = [ python nodejs ] ++ stdenv.lib.optional (stdenv.isLinux) utillinux ++ args.buildInputs or [];
      buildCommand = ''
        mkdir -p $out/bin
        cat > $out/bin/shell <<EOF
        #! ${stdenv.shell} -e
        $shellHook
        exec ${stdenv.shell}
        EOF
        chmod +x $out/bin/shell
      '';

      # Provide the dependencies in a development shell through the NODE_PATH environment variable
      inherit nodeDependencies;
      shellHook = stdenv.lib.optionalString (dependencies != []) ''
        export NODE_PATH=$nodeDependencies/lib/node_modules
      '';
    };
in
{ inherit buildNodeSourceDist buildNodePackage buildNodeShell; }