{
  description = "Landkreis-Sprints";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    rust-overlay.url = "github:oxalica/rust-overlay";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { nixpkgs, rust-overlay, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs {
          inherit system;
          overlays = [ (import rust-overlay) ];
        };

        rust = pkgs.rust-bin.stable.latest.default.override {
          extensions = [
            "rustfmt"
            "clippy"
          ];
        };
      in {
        devShells.default = pkgs.mkShell {
          packages = with pkgs; [
            rust

            postgresql
            postgis

            sqlx-cli

            gdal
            geos
            proj

            pkg-config
            openssl
          ];

          shellHook = ''
            export PGDATA="$PWD/.pgdata"
            export PGHOST="$PWD/.pgsocket"
            export PGPORT="5433"
            export PGDATABASE="county_sprints"
            export PGUSER="county_sprints"

            mkdir -p "$PGHOST"

            if [ ! -f "$PGDATA/PG_VERSION" ]; then
              echo "initialising PostgreSQL..."

              initdb \
                --auth=trust \
                --no-locale \
                "$PGDATA" >/dev/null

              cat >> "$PGDATA/postgresql.conf" <<PGEOF
listen_addresses = ''
port = 5433
unix_socket_directories = '$PGHOST'
PGEOF
            fi

            if ! pg_ctl -D "$PGDATA" status >/dev/null 2>&1; then
              pg_ctl \
                -D "$PGDATA" \
                -o "-k $PGHOST -p $PGPORT" \
                -l "$PGDATA/postgresql.log" \
                start >/dev/null
            fi

            if ! psql \
              -h "$PGHOST" \
              -p "$PGPORT" \
              -d postgres \
              -tAc "SELECT 1 FROM pg_roles WHERE rolname='$PGUSER'" |
              grep -q 1
            then
              createuser \
                -h "$PGHOST" \
                -p "$PGPORT" \
                "$PGUSER"
            fi

            if ! psql \
              -h "$PGHOST" \
              -p "$PGPORT" \
              -d postgres \
              -tAc "SELECT 1 FROM pg_database WHERE datname='$PGDATABASE'" |
              grep -q 1
            then
              createdb \
                -h "$PGHOST" \
                -p "$PGPORT" \
                -O "$PGUSER" \
                "$PGDATABASE"
            fi

            if ! psql \
              -h "$PGHOST" \
              -p "$PGPORT" \
              -d "$PGDATABASE" \
              -tAc "SELECT 1 FROM pg_extension WHERE extname='postgis'" |
              grep -q 1
            then
              psql \
                -h "$PGHOST" \
                -p "$PGPORT" \
                -d "$PGDATABASE" \
                -c "CREATE EXTENSION postgis;" >/dev/null
            fi

            export DATABASE_URL="postgresql://$PGUSER@/$PGDATABASE?host=$PGHOST&port=$PGPORT"

            echo
            echo "========================================"
            echo " county-sprints development environment"
            echo "========================================"
            echo "DATABASE_URL=$DATABASE_URL"
            echo
          '';
        };
      }
    );
}