# ============================================================================
# FS & Storage Configuration
# ============================================================================
# This module defines:
# - Disko partition layout (EFI, swap, root)
# - Filesystem options (device, swap size)
#
# Only applies to systems with physical disk management needs
# (not containers, not WSL, not systems without a configured device)

{ config, lib, ... }:

let
  cfg = config.athenix.host.filesystem;
  # Only enable disk config if device is set and disko is enabled
  hasDiskConfig = cfg.device != null && config.disko.enableConfig;
in
{
  options.athenix = {
    host.filesystem = {
      device = lib.mkOption {
        type = lib.types.nullOr lib.types.str;
        default = null;
        description = ''
          The main disk device to use for automated partitioning and installation.

          When set, enables disko for declarative disk management with:
          - 1GB EFI boot partition
          - Optional swap partition (see swapSize)
          - Root partition using remaining space

          Leave null for systems that don't need disk partitioning (containers, WSL).
        '';
        example = "/dev/nvme0n1";
      };
      useSwap = lib.mkOption {
        type = lib.types.bool;
        default = true;
        description = ''
          Whether to create and use a swap partition.
          Disable for systems with ample RAM or SSDs where swap is undesirable.
        '';
      };
      swapSize = lib.mkOption {
        type = lib.types.nullOr lib.types.str;
        default = null;
        description = ''
          Size of the swap partition (e.g., "16G", "32G").

          Recommended sizes:
          - 8-16GB for desktops with 16GB+ RAM
          - 32GB for laptops (enables hibernation)
          - Match RAM size for systems <8GB RAM
        '';
        example = "32G";
      };
    };
  };

  config = lib.mkMerge [
    {
      # ========== Disk Partitioning (Disko) ==========
      disko.enableConfig = lib.mkDefault (cfg.device != null);
    }

    (lib.mkIf hasDiskConfig {
      disko.devices = {
        disk.main = {
          type = "disk";
          device = cfg.device;
          content = {
            type = "gpt";
            partitions = {
              # EFI System Partition
              ESP = {
                name = "ESP";
                label = "BOOT";
                size = "1G";
                type = "EF00";
                content = {
                  type = "filesystem";
                  format = "vfat";
                  mountpoint = "/boot";
                  mountOptions = [ "umask=0077" ];
                  extraArgs = [
                    "-n"
                    "BOOT"
                  ];
                };
              };

              # Swap Partition (size configurable per host)
              swap = lib.mkIf cfg.useSwap {
                name = "swap";
                label = "swap";
                size = cfg.swapSize;
                content = {
                  type = "swap";
                };
              };

              # Root Partition (takes remaining space)
              root = {
                name = "root";
                label = "root";
                size = "100%";
                content = {
                  type = "filesystem";
                  format = "ext4";
                  mountpoint = "/";
                  extraArgs = [
                    "-L"
                    "ROOT"
                  ];
                };
              };
            };
          };
        };
      };
    })
  ];
}