# Copyright Tom Hubrecht, (2023-2024)
# SPDX-FileCopyrightText: 2024 Tom Hubrecht <tom.hubrecht@dgnum.eu>
#
# SPDX-License-Identifier: EUPL-1.2

{
  patchFile,
  excludeGitHubManual ? true,
  fetchers ? { },
}:

rec {
  base =
    { pkgs }:
    rec {
      mkUrlPatch =
        attrs:
        pkgs.fetchpatch (
          {
            hash = pkgs.lib.fakeHash;
          }
          // attrs
          // (pkgs.lib.optionalAttrs (excludeGitHubManual && !(builtins.hasAttr "includes" attrs)) {
            excludes = (attrs.excludes or [ ]) ++ [ "nixos/doc/manual/*" ];
          })
        );

      mkGitHubPatch =
        { id, ... }@attrs:
        mkUrlPatch (
          (builtins.removeAttrs attrs [ "id" ])
          // {
            url = "https://github.com/NixOS/nixpkgs/pull/${builtins.toString id}.diff";
          }
        );

      mkCommitPatch =
        { sha, ... }@attrs:
        mkUrlPatch (
          (builtins.removeAttrs attrs [ "sha" ])
          // {
            url = "https://github.com/NixOS/nixpkgs/commit/${builtins.toString sha}.diff";
          }
        );

      patchFunctions = {
        commit = mkCommitPatch;
        github = mkGitHubPatch;
        remote = pkgs.fetchpatch;
        static = attrs: attrs.path;
        url = mkUrlPatch;
      } // fetchers;

      mkPatch =
        {
          _type ? "github",
          ...
        }@attrs:
        if builtins.hasAttr _type patchFunctions then
          patchFunctions.${_type} (builtins.removeAttrs attrs [ "_type" ])
        else
          throw "Unknown patch type: ${builtins.toString _type}.";

      mkPatches = v: builtins.map mkPatch ((import patchFile).${v} or [ ]);

      applyPatches =
        {
          src,
          name,
          patches ? mkPatches name,
        }:
        if patches == [ ] then
          src
        else
          pkgs.applyPatches {
            inherit patches src;

            name = "${name}-patched";
          };

      applyPatches' = name: src: applyPatches { inherit name src; };
    };

  mkNixpkgsSrc = { src, name }: (base { pkgs = import src { }; }).applyPatches { inherit src name; };
}