{
  lib,
  stdenv,
  writeShellScriptBin,
  coreutils,
  bash,
}: let
  script = writeShellScriptBin "crunch" ''
    #!/usr/bin/env bash
    set -euo pipefail

    # ═══════════════════════════════════════════════════════════════
    # crunch — Voice-notified reminders & AI crunch jobs
    #          via systemd transient timers.
    #
    # Requires: talk (ElevenLabs TTS) in PATH, ELEVENLABS_API_KEY env.
    # Optional: pi, opencode for AI crunch mode.
    # ═══════════════════════════════════════════════════════════════

    TALK="''${TALK:-talk}"
    SELF="$(readlink -f "''${BASH_SOURCE[0]:-$0}")"

    # ── Helpers ───────────────────────────────────────────────────

    usage() {
      cat <<'EOF'
    crunch — voice-notified reminders and AI jobs via systemd timers

    Usage:
      crunch at <time> <message>              One-shot (14:30 or "2026-07-03 14:30")
      crunch in <duration> <message>          One-shot after delay (30m, 2h, 1h30m)
      crunch daily <time> <message>           Recurring daily at time
      crunch weekly <day> <time> <message>    Recurring weekly (Mon or Montag)
      crunch ai <engine> <type> <time> <prompt>  AI crunch (pi|opencode)
      crunch script <type> <time> <script.sh> [args]  Custom script → talk
      crunch list                              List active jobs
      crunch cancel <name>                     Cancel a job
      crunch purge                             Remove fired one-shot jobs

    Examples:
      crunch at "14:30" "Müll rausbringen"
      crunch at "2026-07-03 10:00" "Zahnarzttermin"
      crunch in "30m" "Build checken"
      crunch daily "09:00" "Daily standup"
      crunch weekly "Mon 09:00" "Weekly review"
      crunch weekly "Montag 09:00" "Weekly review"
      crunch ai pi in "1h" "Fasse neueste Commits zusammen"
      crunch ai opencode daily "08:00" "Review offene Issues"
      crunch script daily "08:00" ~/scripts/basecamp-daily.sh
      crunch list
      crunch cancel mll-rausbringen-12345

    Environment:
      VOICE_NOTIFY=0       Silence voice output (passed to talk)
      ELEVENLABS_API_KEY   Required by talk
      TALK                 Override path to talk binary
    EOF
    }

    # German → systemd day abbreviations
    norm_day() {
      local d="''${1,,}"
      d="''${d%%.*}"  # strip trailing dot (German abbreviation)
      case "$d" in
        mo|mon|monday|montag)        echo "Mon" ;;
        di|tue|tues|tuesday|dienstag) echo "Tue" ;;
        mi|wed|weds|wednesday|mittwoch) echo "Wed" ;;
        do|thu|thur|thurs|thursday|donnerstag) echo "Thu" ;;
        fr|fri|friday|freitag)        echo "Fri" ;;
        sa|sat|saturday|samstag)      echo "Sat" ;;
        so|su|sun|sunday|sonntag)     echo "Sun" ;;
        *)                            echo "''${1^}" ;;
      esac
    }

    make_name() {
      local msg="''${1:?No message}"
      local slug
      slug="''${msg,,}"
      slug="''${slug//[^a-z0-9 ]/}"
      slug="''${slug// /-}"
      slug="''${slug:0:25}"
      slug="''${slug%-}"  # trim trailing dash
      echo "crunch-''${slug:-job}-$RANDOM"
    }

    # schedule <type> <time_spec> <exec_cmd> <name>
    schedule() {
      local type="$1" time_spec="$2" exec_cmd="$3" name="$4"
      local timer_flag=""

      case "$type" in
        at)
          if [[ "$time_spec" == *' '* ]]; then
            # "2026-07-03 14:30" → specific date
            timer_flag="--on-calendar=''${time_spec}:00"
          else
            # "14:30" → next matching time
            timer_flag="--on-calendar=*-*-* ''${time_spec}:00"
          fi
          ;;
        in)
          timer_flag="--on-active=''${time_spec}"
          ;;
        daily)
          timer_flag="--on-calendar=*-*-* ''${time_spec}:00"
          ;;
        weekly)
          local day time_part
          day="$(norm_day "''${time_spec%% *}")"
          time_part="''${time_spec##* }"
          timer_flag="--on-calendar=''${day} *-*-* ''${time_part}:00"
          ;;
        *)
          echo "Unknown schedule type: $type" >&2
          exit 1
          ;;
      esac

      systemd-run --user \
        --unit="''${name}" \
        --description="crunch job" \
        "''${timer_flag}" \
        bash -lc "''${exec_cmd}" \
        && echo "✓ Scheduled: $name"
    }

    # ── Internal execution (called by systemd) ────────────────────

    case "''${1:-}" in
      _say)
        shift
        exec "$TALK" "$*"
        ;;
      _ai)
        engine="$2"; shift 2
        case "$engine" in
          pi|pi-agent)
            pi -p "$*" | "$TALK"
            ;;
          opencode|oc)
            opencode run "$*" -q | "$TALK"
            ;;
          *)
            echo "Unknown engine: $engine (use: pi, opencode)" >&2
            exit 1
            ;;
        esac
        exit $?
        ;;
      _script)
        script_path="$2"; shift 2
        rc=0
        output=$(bash "$script_path" "$@" 2>&1) || rc=$?
        if [ -n "''${output:-}" ]; then
          printf '%s' "$output" | "$TALK"
        fi
        exit "$rc"
        ;;
    esac

    # ── CLI ───────────────────────────────────────────────────────

    [ $# -lt 1 ] && { usage; exit 0; }

    cmd="$1"; shift

    case "$cmd" in
      # ── Simple voice reminders ──
      at)
        [ $# -lt 2 ] && { echo "Usage: crunch at <time> <message>" >&2; exit 1; }
        time_spec="$1"; shift
        msg="$*"
        name="$(make_name "$msg")"
        schedule at "$time_spec" "$SELF _say $(printf '%q' "$msg")" "$name"
        ;;

      in)
        [ $# -lt 2 ] && { echo "Usage: crunch in <duration> <message>" >&2; exit 1; }
        duration="$1"; shift
        msg="$*"
        name="$(make_name "$msg")"
        schedule in "$duration" "$SELF _say $(printf '%q' "$msg")" "$name"
        ;;

      daily)
        [ $# -lt 2 ] && { echo "Usage: crunch daily <time> <message>" >&2; exit 1; }
        time_spec="$1"; shift
        msg="$*"
        name="$(make_name "$msg")"
        schedule daily "$time_spec" "$SELF _say $(printf '%q' "$msg")" "$name"
        ;;

      weekly)
        [ $# -lt 2 ] && { echo "Usage: crunch weekly <day> <time> <message>" >&2; exit 1; }
        day_time="$1"; shift
        msg="$*"
        name="$(make_name "$msg")"
        schedule weekly "$day_time" "$SELF _say $(printf '%q' "$msg")" "$name"
        ;;

      # ── AI crunch jobs ──
      ai)
        [ $# -lt 4 ] && { echo "Usage: crunch ai <pi|opencode> <at|in|daily|weekly> <time> <prompt>" >&2; exit 1; }
        engine="$1"; sub_type="$2"; time_spec="$3"; shift 3
        prompt="$*"
        name="$(make_name "$prompt")"
        schedule "$sub_type" "$time_spec" \
          "$SELF _ai $engine $(printf '%q' "$prompt")" "$name"
        ;;

      # ── Custom script crunch jobs ──
      script)
        [ $# -lt 3 ] && { echo "Usage: crunch script <at|in|daily|weekly> <time> <script.sh> [args...]" >&2; exit 1; }
        sub_type="$1"; time_spec="$2"; script_path="$3"; shift 3
        script_path="$(readlink -f "$script_path")"
        [ ! -f "$script_path" ] && { echo "Script not found: $script_path" >&2; exit 1; }
        name="$(make_name "$(basename "$script_path" .sh)")"
        exec_cmd="$SELF _script $(printf '%q' "$script_path")"
        if [ $# -gt 0 ]; then
          exec_cmd+=" $(printf '%q ' "$@")"
        fi
        schedule "$sub_type" "$time_spec" "$exec_cmd" "$name"
        ;;

      # ── Management ──
      list)
        echo "Active crunch jobs:"
        echo "───────────────────────────────────"
        systemctl --user list-timers 'crunch-*' --no-pager 2>/dev/null \
          | grep -E 'crunch-|^NEXT|^NEXT|^$' || echo "  (none)"
        ;;

      cancel)
        [ $# -lt 1 ] && { echo "Usage: crunch cancel <name>" >&2; exit 1; }
        name="$1"
        # Accept with or without crunch- prefix
        [[ "$name" != crunch-* ]] && name="crunch-$name"
        systemctl --user stop "''${name}.timer" "''${name}.service" 2>/dev/null \
          && echo "✓ Cancelled: $name" \
          || echo "✗ Not found: $name"
        ;;

      purge)
        echo "Purging fired one-shot jobs..."
        local purged=0
        for unit in $(systemctl --user list-units 'crunch-*' --all --plain --no-legend --no-pager 2>/dev/null | awk '{print $1}'); do
          if systemctl --user is-failed "$unit" &>/dev/null; then
            systemctl --user stop "$unit" 2>/dev/null || true
            systemctl --user reset-failed "$unit" 2>/dev/null || true
            echo "  Purged: $unit"
            purged=$((purged + 1))
          fi
        done
        echo "✓ Purged $purged unit(s)"
        ;;

      -h|--help|help)
        usage
        ;;

      *)
        echo "Unknown command: $cmd" >&2
        echo ""
        usage
        exit 1
        ;;
    esac
  '';
in
  stdenv.mkDerivation {
    pname = "crunch";
    version = "0.1.0";

    dontUnpack = true;

    installPhase = ''
      mkdir -p "$out/bin"
      ln -s ${script}/bin/crunch "$out/bin/crunch"
    '';

    meta = with lib; {
      description = "Voice-notified reminders and AI crunch jobs via systemd transient timers";
      homepage = "https://code.m3ta.dev/m3tam3re/nixpkgs";
      license = licenses.mit;
      platforms = platforms.linux;
      mainProgram = "crunch";
    };
  }