# Support functions to create a nix generated workspace for out-of-tree sources.
#
# You do not need to check this in since it will be regenerated every time it is
# used by crate2nix.
#
# This file was @generated by crate2nix 0.9.0-alpha.1 with the command:
#   "generate"
#
# See https://github.com/kolloch/crate2nix for more info.

{ nixpkgs ? <nixpkgs>
, pkgs ? import nixpkgs {}
, lib ? pkgs.lib
# The path to crate2nix.json.
, crate2nixJson ? ./crate2nix.json
}:

let config = builtins.fromJSON (builtins.readFile crate2nixJson);
    sources = config.sources or (builtins.throw "no sources in ${crate2nixJson}");
in
rec {
    /* An attrset mapping a source name to its source (as a derivation). */
    fetchedSourcesByName = lib.mapAttrs internal.sourceFromConfig sources;

    /* A derivation building a directory symlinking all workspace member sources
       by their name.
    */
    fetchedSources =
        let sources = lib.mapAttrsToList (name: path: { inherit name path; }) fetchedSourcesByName;
        in
        pkgs.linkFarm "crate2nix-sources" sources;

    internal = rec {
        sourceFromConfig = name: { type, ... } @ source:
            assert builtins.isString name;
            assert builtins.isString type;

            if type == "Git"
            then pkgs.fetchgit {
                url = source.url;
                rev = source.rev;
                sha256 = source.sha256;
            }
            else if type == "CratesIo"
            then downloadFromCratesIo source
            else if type == "Nix"
            then resolveNix source
            else builtins.throw "Unexpected source type '${type}' for source: ${builtins.toJSON source}";

        /* Resolves a source configuration of type "Nix".

           It can either have

           * a `{ package = ...; ... }` path which will be resolved with pkg.callPackage

           * or an `{ import = ...; ... }` path which will be imported.

           Within that context and additional optional `attr` attribute path is resolved.

           E.g.
           ```nix
           {
                type = "Nix";
                import = "./nix/sources.nix";
                attr = "myPackage.release";
           }
           ```
        */
        resolveNix = { type, ... } @ source:
            assert type == "Nix";

            let attrs =
                    if source ? package
                    then pkgs.callPackage (./. + "/${source.package}") {}
                    else if source ? "import"
                    then import (./. + ''/${source."import"}'')
                    else builtins.throw "Neither import nor package in nix source.";
                attrPath = lib.splitString "." source.attr;
                sourceDerivation =
                    if source ? attr
                    then lib.attrByPath
                        attrPath
                        (builtins.throw
                            ''
                            Did not find attribute '${source.attr or ""}'
                            in '${source.package or source.import or "missing file"}'.
                            '')
                        attrs
                    else attrs;
            in
            sourceDerivation;

        downloadFromCratesIo = { type, name, version, sha256 }:
            assert type == "CratesIo";

            let archive = pkgs.fetchurl {
                name = "${name}-${version}.tar.gz";
                url = "https://crates.io/api/v1/crates/${name}/${version}/download";
                inherit sha256;
            };
            in pkgs.runCommand (lib.removeSuffix ".tar.gz" name) {}
            ''
                mkdir -p $out
                tar -xzf ${archive} --strip-components=1 -C $out
            '';
    };
}