# This file has been generated by Niv.
_:
let

  #
  # The fetchers. fetch_<type> fetches specs of type <type>.
  #

  fetch_file = pkgs: spec:
    if spec.builtin or true then
      builtins_fetchurl { inherit (spec) url sha256; }
    else
      pkgs.fetchurl { inherit (spec) url sha256; };

  fetch_tarball = pkgs: name: spec:
    let
      ok = str: ! builtins.isNull (builtins.match "[a-zA-Z0-9+-._?=]" str);
      # sanitize the name, though nix will still fail if name starts with period
      name' = stringAsChars (x: if ! ok x then "-" else x) "${name}-src";
    in
    if spec.builtin or true then
      builtins_fetchTarball { name = name'; inherit (spec) url sha256; }
    else
      pkgs.fetchzip { name = name'; inherit (spec) url sha256; };

  fetch_git = spec:
    builtins.fetchGit { url = spec.repo; inherit (spec) rev ref; };

  fetch_local = spec: spec.path;

  fetch_builtin-tarball = name: throw
    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
        $ niv modify ${name} -a type=tarball -a builtin=true'';

  fetch_builtin-url = name: throw
    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
        $ niv modify ${name} -a type=file -a builtin=true'';

  #
  # Various helpers
  #

  # The set of packages used when specs are fetched using non-builtins.
  mkPkgs = sources:
    let
      sourcesNixpkgs =
        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) { };
      hasNixpkgsPath = builtins.any (x: x.prefix == "nixpkgs") builtins.nixPath;
      hasThisAsNixpkgsPath = <nixpkgs> == ./.;
    in
    if builtins.hasAttr "nixpkgs" sources
    then sourcesNixpkgs
    else if hasNixpkgsPath && ! hasThisAsNixpkgsPath then
      import <nixpkgs> { }
    else
      abort
        ''
          Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
          add a package called "nixpkgs" to your sources.json.
        '';

  # The actual fetching function.
  fetch = pkgs: name: spec:

    if ! builtins.hasAttr "type" spec then
      abort "ERROR: niv spec ${name} does not have a 'type' attribute"
    else if spec.type == "file" then fetch_file pkgs spec
    else if spec.type == "tarball" then fetch_tarball pkgs name spec
    else if spec.type == "git" then fetch_git spec
    else if spec.type == "local" then fetch_local spec
    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
    else if spec.type == "builtin-url" then fetch_builtin-url name
    else
      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";

  # If the environment variable NIV_OVERRIDE_${name} is set, then use
  # the path directly as opposed to the fetched source.
  replace = name: drv:
    let
      saneName = stringAsChars (c: if isNull (builtins.match "[a-zA-Z0-9]" c) then "_" else c) name;
      ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
    in
    if ersatz == "" then drv else ersatz;

  # Ports of functions for older nix versions

  # a Nix version of mapAttrs if the built-in doesn't exist
  mapAttrs = builtins.mapAttrs or (
    f: set: with builtins;
    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
  );

  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/lists.nix#L295
  range = first: last: if first > last then [ ] else builtins.genList (n: first + n) (last - first + 1);

  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L257
  stringToCharacters = s: map (p: builtins.substring p 1 s) (range 0 (builtins.stringLength s - 1));

  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L269
  stringAsChars = f: s: concatStrings (map f (stringToCharacters s));
  concatStrings = builtins.concatStringsSep "";

  # fetchTarball version that is compatible between all the versions of Nix
  builtins_fetchTarball = { url, name, sha256 }@attrs:
    let
      inherit (builtins) lessThan nixVersion fetchTarball;
    in
    if lessThan nixVersion "1.12" then
      fetchTarball { inherit name url; }
    else
      fetchTarball attrs;

  # fetchurl version that is compatible between all the versions of Nix
  builtins_fetchurl = { url, sha256 }@attrs:
    let
      inherit (builtins) lessThan nixVersion fetchurl;
    in
    if lessThan nixVersion "1.12" then
      fetchurl { inherit url; }
    else
      fetchurl attrs;

  # Create the final "sources" from the config
  mkSources = config:
    mapAttrs
      (
        name: spec:
          if builtins.hasAttr "outPath" spec
          then
            abort
              "The values in sources.json should not have an 'outPath' attribute"
          else
            spec // { outPath = replace name (fetch config.pkgs name spec); }
      )
      config.sources;

  # The "config" used by the fetchers
  mkConfig =
    { sourcesFile ? if builtins.pathExists ./sources.json then ./sources.json else null
    , sources ? if isNull sourcesFile then { } else builtins.fromJSON (builtins.readFile sourcesFile)
    , pkgs ? mkPkgs sources
    }: rec {
      # The sources, i.e. the attribute set of spec name to spec
      inherit sources;

      # The "pkgs" (evaluated nixpkgs) to use for e.g. non-builtin fetchers
      inherit pkgs;
    };

in
mkSources (mkConfig { }) // { __functor = _: settings: mkSources (mkConfig settings); }
