# Code for buildRustCrate, a Nix function that builds Rust code, just
# like Cargo, but using Nix instead.
#
# This can be useful for deploying packages with NixOps, and to share
# binary dependencies between projects.

{ lib, buildPlatform, stdenv, defaultCrateOverrides, fetchCrate, ncurses, rustc  }:

let buildCrate = { crateName, crateVersion, crateAuthors, buildDependencies,
                   dependencies, completeDeps, completeBuildDeps,
                   crateFeatures, libName, build, release, libPath,
                   crateType, metadata, crateBin, finalBins,
                   verbose, colors }:

      let depsDir = lib.concatStringsSep " " dependencies;
          completeDepsDir = lib.concatStringsSep " " completeDeps;
          completeBuildDepsDir = lib.concatStringsSep " " completeBuildDeps;
          makeDeps = dependencies:
            (lib.concatMapStringsSep " " (dep:
              let extern = lib.strings.replaceStrings ["-"] ["_"] dep.libName; in
              (if dep.crateType == "lib" then
                 " --extern ${extern}=${dep.out}/lib/lib${extern}-${dep.metadata}.rlib"
              else
                 " --extern ${extern}=${dep.out}/lib/lib${extern}-${dep.metadata}${buildPlatform.extensions.sharedLibrary}")
            ) dependencies);
          deps = makeDeps dependencies;
          buildDeps = makeDeps buildDependencies;
          optLevel = if release then 3 else 0;
          rustcOpts = (if release then "-C opt-level=3" else "-C debuginfo=2");
          rustcMeta = "-C metadata=${metadata} -C extra-filename=-${metadata}";
          version_ = lib.splitString "-" crateVersion;
          versionPre = if lib.tail version_ == [] then "" else builtins.elemAt version_ 1;
          version = lib.splitString "." (lib.head version_);
          authors = lib.concatStringsSep ":" crateAuthors;
      in ''
      norm=""
      bold=""
      green=""
      boldgreen=""
      if [[ "${colors}" -eq "always" ]]; then
        norm="$(printf '\033[0m')" #returns to "normal"
        bold="$(printf '\033[0;1m')" #set bold
        green="$(printf '\033[0;32m')" #set green
        boldgreen="$(printf '\033[0;1;32m')" #set bold, and set green.
      fi

      echo_build_heading() {
       start=""
       end=""
       if [[ x"${colors}" -eq x"always" ]]; then
         start="$(printf '\033[0;1;32m')" #set bold, and set green.
         end="$(printf '\033[0m')" #returns to "normal"
       fi
       if (( $# == 1 )); then
         echo "$start""Building $1""$end"
       else
         echo "$start""Building $1 ($2)""$end"
       fi
      }

      noisily() {
        start=""
        end=""
        if [[ x"${colors}" -eq x"always" ]]; then
          start="$(printf '\033[0;1;32m')" #set bold, and set green.
          end="$(printf '\033[0m')" #returns to "normal"
        fi
	${lib.optionalString verbose ''
            echo -n "$start"Running "$end"
            echo $@
	''}
	$@
      }

      symlink_dependency() {
      # $1 is the nix-store path of a dependency
        i=$1
	dest=target/deps
	if [ ! -z $2 ]; then
           if [ "$2" = "--buildDep" ]; then
             dest=target/buildDeps
           fi
	fi
        ln -s -f $i/lib/*.rlib $dest #*/
        ln -s -f $i/lib/*.so $i/lib/*.dylib $dest #*/
        if [ -e "$i/lib/link" ]; then
            cat $i/lib/link >> target/link
            cat $i/lib/link >> target/link.final
        fi
        if [ -e $i/env ]; then
            source $i/env
        fi
      }

      build_lib() {
         lib_src=$1
         echo_build_heading $lib_src ${libName}

         noisily rustc --crate-name $CRATE_NAME $lib_src --crate-type ${crateType} \
           ${rustcOpts} ${rustcMeta} ${crateFeatures} --out-dir target/lib \
           --emit=dep-info,link -L dependency=target/deps ${deps} --cap-lints allow \
           $BUILD_OUT_DIR $EXTRA_BUILD $EXTRA_FEATURES --color ${colors}

         EXTRA_LIB=" --extern $CRATE_NAME=target/lib/lib$CRATE_NAME-${metadata}.rlib"
         if [ -e target/deps/lib$CRATE_NAME-${metadata}${buildPlatform.extensions.sharedLibrary} ]; then
            EXTRA_LIB="$EXTRA_LIB --extern $CRATE_NAME=target/lib/lib$CRATE_NAME-${metadata}${buildPlatform.extensions.sharedLibrary}"
         fi
      }

      build_bin() {
        crate_name=$1
        crate_name_=$(echo $crate_name | sed -e "s/-/_/g")
	main_file=""
	if [[ ! -z $2 ]]; then
          main_file=$2
	fi
	echo_build_heading $@
	noisily rustc --crate-name $crate_name_ $main_file --crate-type bin ${rustcOpts}\
          ${crateFeatures} --out-dir target/bin --emit=dep-info,link -L dependency=target/deps \
          $LINK ${deps}$EXTRA_LIB --cap-lints allow \
          $BUILD_OUT_DIR $EXTRA_BUILD $EXTRA_FEATURES --color ${colors}
        if [ "$crate_name_" -ne "$crate_name" ]; then
          mv target/bin/$crate_name_ target/bin/$crate_name
        fi
      }

      runHook preBuild
      mkdir -p target/{deps,lib,build,buildDeps}
      chmod uga+w target -R
      for i in ${completeDepsDir}; do
        symlink_dependency $i
      done
      for i in ${completeBuildDepsDir}; do
         symlink_dependency $i --buildDep
      done
      if [ -e target/link ]; then
        sort -u target/link > target/link.sorted
        mv target/link.sorted target/link
        sort -u target/link.final > target/link.final.sorted
        mv target/link.final.sorted target/link.final
        tr '\n' ' ' < target/link > target/link_
      fi
      EXTRA_BUILD=""
      BUILD_OUT_DIR=""
      export CARGO_PKG_NAME=${crateName}
      export CARGO_PKG_VERSION=${crateVersion}
      export CARGO_PKG_AUTHORS="${authors}"
      export CARGO_CFG_TARGET_ARCH=${buildPlatform.parsed.cpu.name}
      export CARGO_CFG_TARGET_OS=${buildPlatform.parsed.kernel.name}

      export CARGO_CFG_TARGET_ENV="gnu"
      export CARGO_MANIFEST_DIR="."
      export DEBUG="${toString (!release)}"
      export OPT_LEVEL="${toString optLevel}"
      export TARGET="${buildPlatform.config}"
      export HOST="${buildPlatform.config}"
      export PROFILE=${if release then "release" else "debug"}
      export OUT_DIR=$(pwd)/target/build/${crateName}.out
      export CARGO_PKG_VERSION_MAJOR=${builtins.elemAt version 0}
      export CARGO_PKG_VERSION_MINOR=${builtins.elemAt version 1}
      export CARGO_PKG_VERSION_PATCH=${builtins.elemAt version 2}
      if [ -n "${versionPre}" ]; then
        export CARGO_PKG_VERSION_PRE="${versionPre}"
      fi

      BUILD=""
      if [[ ! -z "${build}" ]] ; then
         BUILD=${build}
      elif [[ -e "build.rs" ]]; then
         BUILD="build.rs"
      fi
      if [[ ! -z "$BUILD" ]] ; then
         echo_build_heading "$BUILD" ${libName}
         mkdir -p target/build/${crateName}
         EXTRA_BUILD_FLAGS=""
         if [ -e target/link_ ]; then
           EXTRA_BUILD_FLAGS=$(cat target/link_)
         fi
         if [ -e target/link.build ]; then
           EXTRA_BUILD_FLAGS="$EXTRA_BUILD_FLAGS $(cat target/link.build)"
         fi
         noisily rustc --crate-name build_script_build $BUILD --crate-type bin ${rustcOpts} \
          ${crateFeatures} --out-dir target/build/${crateName} --emit=dep-info,link \
          -L dependency=target/buildDeps ${buildDeps} --cap-lints allow $EXTRA_BUILD_FLAGS --color ${colors}

         mkdir -p target/build/${crateName}.out
         export RUST_BACKTRACE=1
         BUILD_OUT_DIR="-L $OUT_DIR"
         mkdir -p $OUT_DIR
         target/build/${crateName}/build_script_build > target/build/${crateName}.opt
         set +e
         EXTRA_BUILD=$(sed -n "s/^cargo:rustc-flags=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ')
         EXTRA_FEATURES=$(sed -n "s/^cargo:rustc-cfg=\(.*\)/--cfg \1/p" target/build/${crateName}.opt | tr '\n' ' ')
         EXTRA_LINK=$(sed -n "s/^cargo:rustc-link-lib=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ')
         EXTRA_LINK_SEARCH=$(sed -n "s/^cargo:rustc-link-search=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ')
         CRATENAME=$(echo ${crateName} | sed -e "s/\(.*\)-sys$/\U\1/")
         grep -P "^cargo:(?!(rustc-|warning=|rerun-if-changed=|rerun-if-env-changed))" target/build/${crateName}.opt \
           | sed -e "s/cargo:\([^=]*\)=\(.*\)/export DEP_$(echo $CRATENAME)_\U\1\E=\2/" > target/env

         set -e
         if [ -n "$(ls target/build/${crateName}.out)" ]; then

            if [ -e "${libPath}" ] ; then
               cp -r target/build/${crateName}.out/* $(dirname ${libPath}) #*/
            else
               cp -r target/build/${crateName}.out/* src #*/
            fi
         fi
      fi

      EXTRA_LIB=""
      CRATE_NAME=$(echo ${libName} | sed -e "s/-/_/g")

      if [ -e target/link_ ]; then
        EXTRA_BUILD="$(cat target/link_) $EXTRA_BUILD"
      fi

      if [ -e "${libPath}" ] ; then
         build_lib ${libPath}
      elif [ -e src/lib.rs ] ; then
         build_lib src/lib.rs
      elif [ -e src/${libName}.rs ] ; then
         build_lib src/${libName}.rs
      fi

      echo "$EXTRA_LINK_SEARCH" | while read i; do
         if [ ! -z "$i" ]; then
           for lib in $i; do
             echo "-L $lib" >> target/link
             L=$(echo $lib | sed -e "s#$(pwd)/target/build#$out/lib#")
             echo "-L $L" >> target/link.final
           done
         fi
      done
      echo "$EXTRA_LINK" | while read i; do
         if [ ! -z "$i" ]; then
           for lib in $i; do
             echo "-l $lib" >> target/link
             echo "-l $lib" >> target/link.final
           done
         fi
      done

      if [ -e target/link ]; then
         sort -u target/link.final > target/link.final.sorted
         mv target/link.final.sorted target/link.final
         sort -u target/link > target/link.sorted
         mv target/link.sorted target/link

         tr '\n' ' ' < target/link > target/link_
         LINK=$(cat target/link_)
       fi

      mkdir -p target/bin
      echo "${crateBin}" | sed -n 1'p' | tr ',' '\n' | while read BIN; do
         if [ ! -z "$BIN" ]; then
           build_bin $BIN
         fi
      done
      ${lib.optionalString (crateBin == "") ''
        if [[ -e src/main.rs ]]; then
          build_bin ${crateName} src/main.rs
        fi
        for i in src/bin/*.rs; do #*/
          build_bin "$(basename $i .rs)" "$i"
        done
      ''}
      # Remove object files to avoid "wrong ELF type"
      find target -type f -name "*.o" -print0 | xargs -0 rm -f
      runHook postBuild
    '' + finalBins;

    installCrate = crateName: ''
      mkdir -p $out
      if [ -s target/env ]; then
        cp target/env $out/env
      fi
      if [ -s target/link.final ]; then
        mkdir -p $out/lib
        cp target/link.final $out/lib/link
      fi
      if [ "$(ls -A target/lib)" ]; then
        mkdir -p $out/lib
        cp target/lib/* $out/lib #*/
      fi
      if [ "$(ls -A target/build)" ]; then # */
        mkdir -p $out/lib
        cp -r target/build/* $out/lib # */
      fi
      if [ "$(ls -A target/bin)" ]; then
        mkdir -p $out/bin
        cp -P target/bin/* $out/bin # */
      fi
    '';
in

crate_: lib.makeOverridable ({ rust, release, verbose, features, buildInputs, crateOverrides }:

let crate = crate_ // (lib.attrByPath [ crate_.crateName ] (attr: {}) crateOverrides crate_);
    processedAttrs = [
      "src" "buildInputs" "crateBin" "crateLib" "libName" "libPath"
      "buildDependencies" "dependencies" "features"
      "crateName" "version" "build" "authors" "colors"
    ];
    extraDerivationAttrs = lib.filterAttrs (n: v: ! lib.elem n processedAttrs) crate;
    buildInputs_ = buildInputs;
in
stdenv.mkDerivation (rec {

    inherit (crate) crateName;

    src = if lib.hasAttr "src" crate then
        crate.src
      else
        fetchCrate { inherit (crate) crateName version sha256; };
    name = "rust_${crate.crateName}-${crate.version}";
    buildInputs = [ rust ncurses ] ++ (crate.buildInputs or []) ++ buildInputs_;
    dependencies =
      builtins.map
        (dep: dep.override { rust = rust; release = release; verbose = verbose; crateOverrides = crateOverrides; })
        (crate.dependencies or []);

    buildDependencies =
      builtins.map
        (dep: dep.override { rust = rust; release = release; verbose = verbose; crateOverrides = crateOverrides; })
        (crate.buildDependencies or []);

    completeDeps = lib.lists.unique (dependencies ++ lib.lists.concatMap (dep: dep.completeDeps) dependencies);
    completeBuildDeps = lib.lists.unique (
      buildDependencies
      ++ lib.lists.concatMap (dep: dep.completeBuildDeps ++ dep.completeDeps) buildDependencies
    );

    crateFeatures = if crate ? features then
        lib.concatMapStringsSep " " (f: "--cfg feature=\\\"${f}\\\"") (crate.features ++ features)
      else "";

    libName = if crate ? libName then crate.libName else crate.crateName;
    libPath = if crate ? libPath then crate.libPath else "";

    metadata = builtins.substring 0 10 (builtins.hashString "sha256" (crateName + "-" + crateVersion));

    crateBin = if crate ? crateBin then
       builtins.foldl' (bins: bin:
          let name =
              lib.strings.replaceStrings ["-"] ["_"]
                 (if bin ? name then bin.name else crateName);
              path = if bin ? path then bin.path else "src/main.rs";
          in
          bins + (if bin == "" then "" else ",") + "${name} ${path}"

       ) "" crate.crateBin
    else "";

    finalBins = if crate ? crateBin then
       builtins.foldl' (bins: bin:
          let name = lib.strings.replaceStrings ["-"] ["_"]
                      (if bin ? name then bin.name else crateName);
              new_name = if bin ? name then bin.name else crateName;
          in
          if name == new_name then bins else
          (bins + "mv target/bin/${name} target/bin/${new_name};")

       ) "" crate.crateBin
    else "";

    build = if crate ? build then crate.build else "";
    crateVersion = crate.version;
    crateAuthors = if crate ? authors && lib.isList crate.authors then crate.authors else [];
    crateType =
      if lib.attrByPath ["procMacro"] false crate then "proc-macro" else
      if lib.attrByPath ["plugin"] false crate then "dylib" else "lib";
    colors = lib.attrByPath [ "colors" ] "always" crate;
    buildPhase = buildCrate {
      inherit crateName dependencies buildDependencies completeDeps completeBuildDeps
              crateFeatures libName build release libPath crateType crateVersion
              crateAuthors metadata crateBin finalBins verbose colors;
    };
    installPhase = installCrate crateName;

} // extraDerivationAttrs)) {
  rust = rustc;
  release = true;
  verbose = true;
  features = [];
  buildInputs = [];
  crateOverrides = defaultCrateOverrides;
}