# Arguments that this derivation gets when it is created with `callPackage`
{ stdenv
, lib
, symlinkJoin
, makeWrapper
, youtube-dl
}:

# the unwrapped mpv derivation - 1st argument to `wrapMpv`
mpv:

let
  # arguments to the function (called `wrapMpv` in all-packages.nix)
  wrapper = {
    extraMakeWrapperArgs ? [],
    youtubeSupport ? true,
    # a set of derivations (probably from `mpvScripts`) where each is
    # expected to have a `scriptName` passthru attribute that points to the
    # name of the script that would reside in the script's derivation's
    # `$out/share/mpv/scripts/`.
    scripts ? [],
    extraUmpvWrapperArgs ? []
  }:
  let
    binPath = lib.makeBinPath ([
      mpv.luaEnv
    ] ++ lib.optionals youtubeSupport [
      youtube-dl
    ] ++ lib.optionals mpv.vapoursynthSupport [
      mpv.vapoursynth.python3
    ]);
    # All arguments besides the input and output binaries (${mpv}/bin/mpv and
    # $out/bin/mpv). These are used by the darwin specific makeWrapper call
    # used to wrap $out/Applications/mpv.app/Contents/MacOS/mpv as well.
    mostMakeWrapperArgs = builtins.concatStringsSep " " ([ "--argv0" "'$0'"
      # These are always needed (TODO: Explain why)
      "--prefix" "LUA_CPATH" "\\;" "${mpv.luaEnv}/lib/lua/${mpv.lua.luaversion}/\\?.so"
      "--prefix" "LUA_PATH" "\\;" "${mpv.luaEnv}/share/lua/${mpv.lua.luaversion}/\\?.lua"
    ] ++ lib.optionals mpv.vapoursynthSupport [
      "--prefix" "PYTHONPATH" ":" "${mpv.vapoursynth}/lib/${mpv.vapoursynth.python3.sitePackages}"
    ] ++ lib.optionals (binPath != "") [
      "--prefix" "PATH" ":" binPath
    ] ++ (lib.lists.flatten (map
      # For every script in the `scripts` argument, add the necessary flags to the wrapper
      (script:
        [
          "--add-flags"
          # Here we rely on the existence of the `scriptName` passthru
          # attribute of the script derivation from the `scripts`
          "--script=${script}/share/mpv/scripts/${script.scriptName}"
        ]
      ) scripts
    )) ++ extraMakeWrapperArgs)
    ;
    umpvWrapperArgs = builtins.concatStringsSep " " ([
      "--argv0" "'$0'"
      "--set" "MPV" "$out/bin/mpv"
    ] ++ extraUmpvWrapperArgs)
    ;
  in
    symlinkJoin {
      name = "mpv-with-scripts-${mpv.version}";

      paths = [ mpv ];

      buildInputs = [ makeWrapper ];

      passthru.unwrapped = mpv;

      postBuild = ''
        # wrapProgram can't operate on symlinks
        rm "$out/bin/mpv"
        makeWrapper "${mpv}/bin/mpv" "$out/bin/mpv" ${mostMakeWrapperArgs}
        rm "$out/bin/umpv"
        makeWrapper "${mpv}/bin/umpv" "$out/bin/umpv" ${umpvWrapperArgs}
      '' + lib.optionalString stdenv.isDarwin ''
        # wrapProgram can't operate on symlinks
        rm "$out/Applications/mpv.app/Contents/MacOS/mpv"
        makeWrapper "${mpv}/Applications/mpv.app/Contents/MacOS/mpv" "$out/Applications/mpv.app/Contents/MacOS/mpv" ${mostMakeWrapperArgs}
      '';
    };
in
  lib.makeOverridable wrapper