{ pkgs, lib, config, ... }:
{
  home.packages = lib.mkIf config.programs.git.enable [
    pkgs.b4
    pkgs.delta
    pkgs.difftastic
    pkgs.git-absorb
    pkgs.git-bug
    pkgs.git-chglog
    pkgs.git-cliff
    pkgs.git-crypt
    pkgs.git-extras
    pkgs.git-filter-repo
    #pkgs.git-publish
    pkgs.git-quick-stats
    pkgs.gitui
    pkgs.tig
  ];
  programs.git = {
    enable = lib.mkDefault true;
    ignores = [ "*~" "*.swp" ];
    package = lib.mkDefault pkgs.gitMinimal;
    aliases = {
      a = "add";
      ab = "absorb";
      abr = "absorb -r";
      ap = "add -p";
      au = "add -u";
      authors = "shortlog -s -n";
      b = "branch";
      bl = "git log -p -M --follow --stat --";
      c = "commit";
      ca = "commit --amend";
      caa = "commit --amend -C@";
      caaa = "commit --amend -C@ -a";
      cf = "commit --fixup";
      co = "checkout";
      d = "diff";
      dc = "diff --cached";
      dcw = "diff --cached --word-diff=color";
      dh = "diff --histogram";
      dp = "diff --patience";
      dt = "difftool --patience";
      dtc = "difftool --cached";
      dw = "diff --word-diff=color";
      g = "grep";
      ign = "ls-files -o -i --exclude-standard";
      l = "log";
      ll = "log --graph --decorate --pretty=oneline --abbrev-commit";
      lp = "log -p --pretty=fuller";
      lpg = "log -p --pretty=fuller -g";
      p = "push -v";
      pf = "push -vf";
      pl = "pull";
      r = "reset";
      rh = "reset --hard";
      ri = "rebase -i";
      rp = "reset -p";
      s = "status";
      spull = "!git-svn fetch && git-svn rebase";
      spush = "!git-svn dcommit";
      ss = "status -s";
      st = "status -uno";
      sw = "switch";
      fetch-local = "!git fetch local && git tag -d $(git describe --exact-match 2>/dev/null >/dev/null) && git fetch --tags local";
      pull-local = "!git fetch-local && git checkout -B master local/master";
      pull-local-old = "!git fetch-local && git checkout HEAD'^' && git branch -f master local/master && git checkout master";
      root = ''!git rev-list --parents HEAD | egrep "^[a-f0-9]{40}$"'';
      has-tag-version = ''!git show-ref --tags -d | grep -qx \"^$(git rev-parse HEAD) refs/tags/v[0-9][0-9][0-9][0-9]\\.[0-9][0-9]\\.[0-9][0-9]\\(\\^{}\\)\\?\"'';
      tag-version = ''"!git has-tag-version && return; v=$(TZ=UTC date +v%Y-%m-%d) && name=$(git rev-parse --show-toplevel | sed -e 's:^.*/work::') && set -x && git tag -s -m \"$name $v\" $v"'';
      has-tag-majordate = ''!git show-ref --tags -d | grep -qx \"^$(git rev-parse HEAD) refs/tags/v[0-9]\\+.[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]\\(\\^{}\\)\\?\"'';
      tag-majordate = ''"!git has-tag-majordate && return; name=$(basename $(dirname $(git rev-parse --show-toplevel))); major=$(basename $(git rev-parse --show-toplevel)); version=''${version:-$(TZ=UTC date +\"v$major.%Y%m%d\")} && set -x && git tag -s -m \"$name $version\" $version"'';
      tag-cabal = ''"!set -x; for cabal in $(git ls-files | grep '.*\\.cabal$'); do name=$(sed -ne 's/^name: *\\(.*\\)/\\1/p' \"$cabal\"); version=$(sed -ne 's/^version: *\\(.*\\)/\\1/p' \"$cabal\"); git tag --merged | grep -Fqx \"$name-$version\" || git tag -f -s -m \"$name v$version\" $name-$version; done"'';
      cl = "notes --ref=changelog append";
      cl-bug = "notes --ref=changelogs/bugs append";
      cl-feature = "notes --ref=changelogs/features append";
      wip = "for-each-ref --sort='authordate:iso8601' --format=' %(color:green)%(authordate:relative)%09%(color:white)%(refname:short)' refs/heads";
    };
    extraConfig = {
      browser.elinks.cmd = "elinks";
      color.branch = "auto";
      color.diff = "auto";
      #color.diff.whitespace = "red reverse";
      color.status = "auto";
      core.commentChar = "auto";
      core.quotepath = "false";
      core.whitespace = "fix,-indent-with-non-tab,trailing-space,cr-at-eol";
      diff.algorithm = "histogram";
      diff.sqldiff.command = "sqldiff";
      format.pretty = "oneline";
      gui.fontdiff = ''-family "DejaVu Sans Mono" -size 8 -weight normal -slant roman -underline 0 -overstrike 0'';
      gui.fontui = ''-family "DejaVu Sans" -size 8 -weight normal -slant roman -underline 0 -overstrike 0'';
      gui.spellingdictionary = "en_US";
      gui.tabsize = 4;
      guitool."Rebase interactive" = {
        cmd = "EDITOR=gvim git rebase -i $REVISION";
        revprompt = true;
      };
      init.defaultBranch = "main";
      merge.tool = "vimdiff";
      merge.conflictStyle = "zdiff3";
      protocol.version = 2;
      pull.rebase = true;
      push.default = "simple";
      rebase.autosquash = "true";
      sendemail.chainReplyTo = "false";
      sendemail.composeencoding = "UTF-8";
      sendemail.confirm = "always";
      sendemail.envelopeSender = "auto";
      sendemail.multiedit = "yes";
      sendemail.suppressFrom = "false";
      sendemail.suppresscc = "self";
      sendemail.thread = "true";
      sendemail.validate = "true";
      web.browser = "elinks";
    };
    iniContent = {
      /*
      diff.external = lib.concatStringsSep " " [
        "${pkgs.difftastic}/bin/difft"
          "--color auto"
          "--background dark"
          "--display side-by-side"
      ];
      */
      # difftastic
      /*
      diff.tool = "difftastic";
      difftool.prompt = false;
      difftool.difftastic.cmd = ''${pkgs.difftastic}/bin/difft "$LOCAL" "$REMOTE"'';
      pager.difftool = true;
      */

      # delta
      /*
      core.pager = "delta --grep-separator-symbol keep";
      interactive.diffFilter = "delta --color-only --features=interactive";
      delta.features = "decorations";
      delta.interactive = {
        keep-plus-minus-markers = false;
      };
      delta.decorations = {
        commit-decoration-style = "blue ol";
        commit-style = "raw";
        file-style = "omit";
        hunk-header-decoration-style = "blue box";
        hunk-header-file-style = "red";
        hunk-header-line-number-style = "#067a00";
        hunk-header-style = "file line-number syntax";
      };
      */
    };
  };
  programs.bash = lib.mkIf config.programs.git.enable {
    shellAliases = {
      g = "git";
      ge = "git-edit-commit";
      gg = "git grep";
      gge = "git-grep-edit";
      gui = "gitui";
    };
    initExtra = ''
      git-edit-commit () { $EDITOR $(git diff-tree --no-commit-id --name-only -r "$@"); }
      git-grep-edit () { $EDITOR $(git grep --name-only --recursive "$@"); }
    '';
  };
}