{ config, lib, pkgs, homeyConfig, ... }:

# Caddy reverse proxy.
#
# Features:
#   - DNS-01 ACME via Cloudflare API → real wildcard cert for *.home.zakobar.com
#   - forward_auth to Authelia for protected vhosts
#   - Plain reverse_proxy for public vhosts (authelia itself, nextcloud)
#   - Listens on :80 (redirect) and :443 (TLS)
#
# Because nixpkgs ships Caddy without the cloudflare DNS plugin by default,
# we build a custom Caddy with it using the xcaddy wrapper from nixpkgs.
#
# Secrets consumed from sops:
#   cloudflare/api_token

let
  cfg    = config.homey.caddy;
  domain = homeyConfig.domain;

  # Build Caddy with the Cloudflare DNS plugin using the nixos-25.05 API.
  # `withPlugins` is a passthru function on the caddy package; it uses xcaddy
  # under the hood to produce a fixed-output derivation.
  caddyWithCloudflare = pkgs.caddy.withPlugins {
    plugins = [
      "github.com/caddy-dns/cloudflare@v0.2.2-0.20250724223520-f589a18c0f5d"
    ];
    hash = "sha256-2Fb2fgM7YhWk9kBnnNGb85MJkAkgzXiI1fb6eK3ykIE=";
  };

  # Reusable Authelia forward_auth snippet
  # Returns a Caddyfile snippet block that applies forward_auth.
  # copy_headers makes Authelia's Remote-* headers available downstream.
  autheliaForwardAuth = ''
    forward_auth localhost:9091 {
      uri /api/verify?rd=https://auth.${domain}
      copy_headers Remote-User Remote-Name Remote-Groups Remote-Email
      # On auth failure, redirect to the authelia login page
      @goauth status 401
      handle_response @goauth {
        redir https://auth.${domain}?rm={method} 302
      }
    }
  '';

in
{
  options.homey.caddy = {
    enable = lib.mkEnableOption "Caddy reverse proxy";

    acmeEmail = lib.mkOption {
      type        = lib.types.str;
      default     = "admin@zakobar.com";
      description = "Email for Let's Encrypt ACME registration.";
    };
  };

  config = lib.mkIf cfg.enable {
    # -----------------------------------------------------------------------
    # Secrets
    # -----------------------------------------------------------------------
    sops.secrets."cloudflare/api_token" = {
      owner = config.services.caddy.user;
    };

    # -----------------------------------------------------------------------
    # Caddy service
    # -----------------------------------------------------------------------
    services.caddy = {
      enable  = true;
      package = caddyWithCloudflare;

      # Global options
      globalConfig = ''
        email ${cfg.acmeEmail}
        # Use Cloudflare DNS-01 challenge for wildcard cert
        acme_dns cloudflare {env.CLOUDFLARE_API_TOKEN}
      '';

      # Each virtual host
      virtualHosts = {

        # ------------------------------------------------------------------
        # Authelia — public, no auth gate (it IS the auth gate)
        # ------------------------------------------------------------------
        "auth.${domain}" = {
          extraConfig = ''
            reverse_proxy localhost:9091
          '';
        };

        # ------------------------------------------------------------------
        # Gitea — protected behind one_factor Authelia
        # ------------------------------------------------------------------
        "git.${domain}" = {
          extraConfig = ''
            ${autheliaForwardAuth}
            reverse_proxy localhost:3000
          '';
        };

        # ------------------------------------------------------------------
        # Nextcloud — public auth (Nextcloud manages its own users + LDAP)
        # Authelia is not gating nextcloud directly because NC has its own
        # login flow.  We still want HTTPS.
        # ------------------------------------------------------------------
        "nextcloud.${domain}" = {
          extraConfig = ''
            # Redirect CardDAV/CalDAV discovery
            redir /.well-known/carddav /remote.php/dav/ 301
            redir /.well-known/caldav  /remote.php/dav/ 301

            # Large uploads (5 GB)
            request_body {
              max_size 5GB
            }

            reverse_proxy localhost:8080
          '';
        };

        # ------------------------------------------------------------------
        # phpLDAPadmin — two_factor, admins only (enforced by authelia policy)
        # ------------------------------------------------------------------
        "ldapadmin.${domain}" = {
          extraConfig = ''
            ${autheliaForwardAuth}
            reverse_proxy localhost:8081
          '';
        };

        # ------------------------------------------------------------------
        # Jellyfin — one_factor (added when enabled)
        # ------------------------------------------------------------------
        "jellyfin.${domain}" = {
          extraConfig = ''
            ${autheliaForwardAuth}
            reverse_proxy localhost:8096
          '';
        };

        # ------------------------------------------------------------------
        # Transmission — two_factor, admins only (enforced by authelia policy)
        # ------------------------------------------------------------------
        "torrent.${domain}" = {
          extraConfig = ''
            ${autheliaForwardAuth}
            reverse_proxy localhost:9092
          '';
          # NOTE: transmission is bound to 9092 to avoid clash with authelia on 9091.
        };

      };
    };

    # -----------------------------------------------------------------------
    # Pass Cloudflare token as env var to the caddy systemd unit.
    #
    # The caddy-dns/cloudflare plugin reads CLOUDFLARE_API_TOKEN directly.
    # sops decrypts the secret to a file at runtime; we write a transient
    # env file to /run/ in ExecStartPre so systemd picks it up via
    # EnvironmentFile.  The file is removed in ExecStopPost.
    # -----------------------------------------------------------------------
    systemd.services.caddy = {
      serviceConfig = {
        EnvironmentFile = "/run/caddy-secrets.env";
        ExecStartPre = [
          (pkgs.writeShellScript "caddy-inject-cf-token" ''
            install -m 0600 /dev/null /run/caddy-secrets.env
            printf 'CLOUDFLARE_API_TOKEN=%s\n' \
              "$(cat ${config.sops.secrets."cloudflare/api_token".path})" \
              > /run/caddy-secrets.env
          '')
        ];
        ExecStopPost = [
          (pkgs.writeShellScript "caddy-cleanup-env" ''
            rm -f /run/caddy-secrets.env
          '')
        ];
      };
      after = lib.mkAfter [ "podman-authelia.service" ];
      wants = lib.mkAfter [ "podman-authelia.service" ];
    };

    # -----------------------------------------------------------------------
    # Firewall — open HTTP + HTTPS (already in common.nix, explicit here too)
    # -----------------------------------------------------------------------
    networking.firewall.allowedTCPPorts = [ 80 443 ];
  };
}