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

with lib;

let
  cfg = config.services.lamassu-server;
  nbLib = config.nix-bitcoin.lib;
  secretsDir = config.nix-bitcoin.secretsDir;

  # Path to the deployed lamassu-server (krops puts it in /var/src)
  lamassuServerPath = "/var/src/lamassu-server-built";

  # Basic hardening settings (simplified from nix-bitcoin)
  defaultHardening = {
    # Sandboxing
    PrivateTmp = true;
    ProtectSystem = "strict";
    ProtectHome = true;
    NoNewPrivileges = true;

    # Kernel
    ProtectKernelTunables = true;
    ProtectKernelModules = true;
    ProtectControlGroups = true;

    # Misc
    RestrictRealtime = true;
    RestrictSUIDSGID = true;
    LockPersonality = true;
  };

in
{
  options.services.lamassu-server = {
    enable = mkEnableOption "Lamassu Bitcoin ATM server";

    serverPort = mkOption {
      type = types.port;
      default = 3000;
      description = "Port for the main lamassu server API";
    };

    # NOTE: Admin UI port is currently hardcoded in upstream lamassu-server:
    # - Production mode (default): port 443
    # - Dev mode (--dev flag): port 8070
    # Future: Add --ui-port support to upstream to make this configurable.
    # This would also enable nginx reverse proxy (which also needs port 443).
    # See docs/lamassu-future-nginx.md for implementation details.

    dataDir = mkOption {
      type = types.path;
      default = "/var/lib/lamassu-server";
      description = "Data directory for lamassu-server";
    };

    user = mkOption {
      type = types.str;
      default = "lamassu-server";
      description = "User to run lamassu-server as";
    };

    group = mkOption {
      type = types.str;
      default = cfg.user;
      description = "Group to run lamassu-server as";
    };

    package = mkOption {
      type = types.path;
      default = lamassuServerPath;
      description = "The path to the lamassu-server source directory";
    };

    logLevel = mkOption {
      type = types.enum [ "error" "warn" "info" "verbose" "debug" "silly" ];
      default = "info";
      description = "Logging level for lamassu-server";
    };

    skip2FA = mkOption {
      type = types.bool;
      default = true;
      description = "Skip 2FA authentication (useful for initial setup)";
    };

    # NOTE: devMode is disabled for now. Admin UI runs in production mode (port 443).
    # Future: Re-enable when --ui-port is added to upstream lamassu-server.
    # devMode = mkOption {
    #   type = types.bool;
    #   default = false;
    #   description = "Run admin server in development mode (port 8070).";
    # };

    database = {
      name = mkOption {
        type = types.str;
        default = cfg.user;
        description = "PostgreSQL database name";
      };

      user = mkOption {
        type = types.str;
        default = cfg.user;
        description = "PostgreSQL username";
      };

      # Password is managed by nix-bitcoin secrets system.
      # See: ${secretsDir}/lamassu-db-password
    };

    hostname = mkOption {
      type = types.str;
      default = "localhost";
      description = ''
        Hostname for the server. This is embedded in the pairing QR code
        and tells ATMs where to connect. Can be an IP address or domain name.
      '';
    };

    # Certificate options (same pattern as LND)
    # TODO: When using an IP address, hostname and certificate.extraIPs are redundant.
    # Consider auto-populating certificate.extraIPs from hostname if it's an IP,
    # or unifying these options. For now, set both to the same IP address.
    certificate = {
      extraIPs = mkOption {
        type = with types; listOf str;
        default = [];
        example = [ "192.168.1.100" ];
        description = ''
          Extra IP addresses to include in the certificate SAN.
        '';
      };
      extraDomains = mkOption {
        type = with types; listOf str;
        default = [];
        example = [ "lamassu.example.com" ];
        description = ''
          Extra domain names to include in the certificate SAN.
        '';
      };
    };

    # Read-only options for certificate paths
    certPath = mkOption {
      readOnly = true;
      default = "${secretsDir}/lamassu-cert";
      description = "Path to the TLS certificate.";
    };

    keyPath = mkOption {
      readOnly = true;
      default = "${secretsDir}/lamassu-key";
      description = "Path to the TLS private key.";
    };

    # NOTE: nginx is disabled for now because admin UI binds directly to port 443.
    # Enabling nginx would cause a port conflict.
    # Future: Add --ui-port to upstream, run admin UI on internal port (e.g., 8070),
    # and use nginx as reverse proxy on 443. See docs/lamassu-future-nginx.md
    # nginx = {
    #   enable = mkEnableOption "Nginx reverse proxy on port 443";
    #   hostname = mkOption {
    #     type = types.nullOr types.str;
    #     default = null;
    #     description = "Hostname for nginx virtual host";
    #   };
    # };

    enableBitcoin = mkOption {
      type = types.bool;
      default = false;
      description = "Enable Bitcoin integration (requires bitcoind)";
    };
  };

  config = mkIf cfg.enable {
    # ═══════════════════════════════════════════════════════════════════════════
    # nix-bitcoin secrets integration
    # ═══════════════════════════════════════════════════════════════════════════

    nix-bitcoin.secrets = {
      lamassu-key.user = cfg.user;
      lamassu-cert = {
        user = cfg.user;
        permissions = "444";  # World readable (it's a public cert)
      };
      lamassu-db-password = {
        user = cfg.user;
        group = "postgres";  # PostgreSQL needs to read this too
      };
    };

    nix-bitcoin.generateSecretsCmds.lamassu = ''
      makeCert lamassu '${nbLib.mkCertExtraAltNames cfg.certificate}'
      makePasswordSecret lamassu-db-password
    '';

    # ═══════════════════════════════════════════════════════════════════════════

    # NOTE: Nginx reverse proxy is disabled. See docs/lamassu-future-nginx.md
    # for future implementation when --ui-port is added to upstream.

    # Enable PostgreSQL
    services.postgresql = {
      enable = true;
      package = pkgs.postgresql_15;
      ensureDatabases = [ cfg.database.name ];
      ensureUsers = [
        {
          name = cfg.database.user;
          ensureDBOwnership = true;
        }
      ];
      # Enable password authentication for localhost connections
      authentication = pkgs.lib.mkOverride 10 ''
        # TYPE  DATABASE        USER            ADDRESS                 METHOD
        local   all             all                                     peer
        host    all             all             127.0.0.1/32            md5
        host    all             all             ::1/128                 md5
      '';
    };

    # Create system users and groups
    users.users = {
      # Lamassu server user
      ${cfg.user} = {
        isSystemUser = true;
        group = cfg.group;
        home = cfg.dataDir;
        createHome = true;
      };
    };

    users.groups.${cfg.group} = {};

    # Create data directory with proper permissions
    systemd.tmpfiles.rules = [
      "d '${cfg.dataDir}' 0770 ${cfg.user} ${cfg.group} - -"
      "d '${cfg.dataDir}/logs' 0770 ${cfg.user} ${cfg.group} - -"
      "d '${cfg.dataDir}/blockchain' 0770 ${cfg.user} ${cfg.group} - -"
      "d '${cfg.dataDir}/ofac' 0770 ${cfg.user} ${cfg.group} - -"
      "d '${cfg.dataDir}/photos' 0770 ${cfg.user} ${cfg.group} - -"
      "d '${cfg.dataDir}/photos/idcards' 0770 ${cfg.user} ${cfg.group} - -"
      "d '${cfg.dataDir}/photos/frontcamera' 0770 ${cfg.user} ${cfg.group} - -"
      "d '${cfg.dataDir}/operator' 0770 ${cfg.user} ${cfg.group} - -"
      # Ensure lamassu-server user can read/write to the source directory
      "Z '${cfg.package}' 0755 ${cfg.user} ${cfg.group} - -"
    ];

    # Service to set PostgreSQL password from nix-bitcoin secrets
    systemd.services.lamassu-postgres-setup = {
      description = "Setup PostgreSQL password for lamassu-server";
      wantedBy = [ "multi-user.target" ];
      after = [ "postgresql.service" "nix-bitcoin-secrets.target" ];
      wants = [ "postgresql.service" ];
      serviceConfig = {
        Type = "oneshot";
        RemainAfterExit = true;
        User = "postgres";
      };
      script = ''
        # Wait for user to exist, then set password from secrets
        for i in {1..30}; do
          if ${pkgs.postgresql}/bin/psql -tAc "SELECT 1 FROM pg_roles WHERE rolname='${cfg.database.user}'" | grep -q 1; then
            echo "Setting password for ${cfg.database.user}..."
            password=$(cat ${secretsDir}/lamassu-db-password)
            ${pkgs.postgresql}/bin/psql -c "ALTER USER \"${cfg.database.user}\" WITH PASSWORD '$password';"
            exit 0
          fi
          echo "Waiting for user ${cfg.database.user} to be created (attempt $i/30)..."
          sleep 1
        done
        echo "ERROR: User ${cfg.database.user} was not created after 30 seconds"
        exit 1
      '';
    };

    # Main lamassu server service
    systemd.services.lamassu-server = {
      description = "Lamassu Bitcoin ATM Server";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" "postgresql.service" "lamassu-postgres-setup.service" "nix-bitcoin-secrets.target" ];
      wants = [ "postgresql.service" "lamassu-postgres-setup.service" ];

      environment = {
        NODE_ENV = "production";

        # Database configuration (password read at runtime from secrets)
        POSTGRES_HOST = "127.0.0.1";
        POSTGRES_PORT = "5432";
        POSTGRES_DB = cfg.database.name;
        POSTGRES_USER = cfg.database.user;

        # Server configuration
        SERVER_PORT = toString cfg.serverPort;
        LOG_LEVEL = cfg.logLevel;
        HOSTNAME = cfg.hostname;

        # SSL/TLS certificates (from nix-bitcoin secrets)
        CA_PATH = cfg.certPath;
        CERT_PATH = cfg.certPath;
        KEY_PATH = cfg.keyPath;

        # Wallet and mnemonic
        MNEMONIC_PATH = "${cfg.dataDir}/lamassu-mnemonic";

        # Data directories
        OFAC_DATA_DIR = "${cfg.dataDir}/ofac";
        ID_PHOTO_CARD_DIR = "${cfg.dataDir}/photos/idcards";
        FRONT_CAMERA_DIR = "${cfg.dataDir}/photos/frontcamera";
        OPERATOR_DATA_DIR = "${cfg.dataDir}/operator";

        # Bitcoin RPC configuration (if enabled)
        BTC_NODE_LOCATION = "remote";
        BTC_WALLET_LOCATION = "remote";
        BTC_NODE_USER = "lamassu";
        BTC_NODE_RPC_HOST = "192.168.0.34";
        BTC_NODE_RPC_PORT = "8332";
        BTC_NODE_PASSWORD = "L3XF8iUrr5FNk2k6mILI";

        # Security
        SKIP_2FA = if cfg.skip2FA then "true" else "false";
      };

      serviceConfig = let
        lamassuEnv = pkgs.writeShellScript "lamassu-env" ''
          #!/bin/bash
          set -euo pipefail
          export PATH=${pkgs.nodejs_22}/bin:$PATH
          # Read database password from nix-bitcoin secrets
          DB_PASSWORD=$(cat ${secretsDir}/lamassu-db-password)
          export DATABASE_URL="postgresql://${cfg.database.user}:$DB_PASSWORD@127.0.0.1:5432/${cfg.database.name}"
          export POSTGRES_PASSWORD="$DB_PASSWORD"
          export NODE_PATH=${cfg.package}/node_modules:${cfg.package}/packages/server/node_modules
          cd ${cfg.package}
          exec "$@"
        '';
      in defaultHardening // {
        WorkingDirectory = "${cfg.package}/packages/server";
        ExecStartPre = [
          # Generate BIP39 mnemonic if it doesn't exist
          "${pkgs.bash}/bin/bash -c 'if [[ ! -f ${cfg.dataDir}/lamassu-mnemonic ]]; then echo \"abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about\" > ${cfg.dataDir}/lamassu-mnemonic && chmod 600 ${cfg.dataDir}/lamassu-mnemonic; fi'"
          # Run database migration
          "${lamassuEnv} ${pkgs.nodejs_22}/bin/node packages/server/bin/lamassu-migrate"
        ];
        ExecStart = "${lamassuEnv} ${pkgs.nodejs_22}/bin/node packages/server/bin/lamassu-server --port ${toString cfg.serverPort} --logLevel ${cfg.logLevel}";

        # Node.js specific overrides
        MemoryDenyWriteExecute = false;

        # Allow read/write access
        ReadWritePaths = [ cfg.dataDir cfg.package "/tmp" ];
        RestrictAddressFamilies = [ "AF_UNIX" "AF_INET" "AF_INET6" ];

        # Service identity
        User = cfg.user;
        Group = cfg.group;
        Restart = "on-failure";
        RestartSec = "10s";
      };

      preStart = ''
        mkdir -p ${cfg.dataDir}/logs

        # Wait for PostgreSQL using peer authentication
        timeout=30
        while ! ${pkgs.postgresql}/bin/psql -h /run/postgresql -U ${cfg.database.user} -d ${cfg.database.name} -c '\q' 2>/dev/null; do
          if [ $timeout -le 0 ]; then
            echo "Timeout waiting for PostgreSQL"
            exit 1
          fi
          echo "Waiting for PostgreSQL..."
          sleep 1
          ((timeout--))
        done
        echo "PostgreSQL is ready"
      '';
    };

    # Admin server service
    systemd.services.lamassu-admin-server = {
      description = "Lamassu Admin Server";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" "lamassu-server.service" ];
      wants = [ "lamassu-server.service" ];

      environment = {
        NODE_ENV = "production";
        LOG_LEVEL = cfg.logLevel;
        HOSTNAME = cfg.hostname;
        CA_PATH = cfg.certPath;
        CERT_PATH = cfg.certPath;
        KEY_PATH = cfg.keyPath;
        # Database configuration (password read at runtime from secrets)
        POSTGRES_HOST = "127.0.0.1";
        POSTGRES_PORT = "5432";
        POSTGRES_DB = cfg.database.name;
        POSTGRES_USER = cfg.database.user;
        MNEMONIC_PATH = "${cfg.dataDir}/lamassu-mnemonic";
        SKIP_2FA = if cfg.skip2FA then "true" else "false";
        # Data directories
        OFAC_DATA_DIR = "${cfg.dataDir}/ofac";
        ID_PHOTO_CARD_DIR = "${cfg.dataDir}/photos/idcards";
        FRONT_CAMERA_DIR = "${cfg.dataDir}/photos/frontcamera";
        OPERATOR_DATA_DIR = "${cfg.dataDir}/operator";
      };

      serviceConfig = let
        lamassuAdminEnv = pkgs.writeShellScript "lamassu-admin-env" ''
          #!/bin/bash
          set -euo pipefail
          export PATH=${pkgs.nodejs_22}/bin:$PATH
          # Read database password from nix-bitcoin secrets
          DB_PASSWORD=$(cat ${secretsDir}/lamassu-db-password)
          export DATABASE_URL="postgresql://${cfg.database.user}:$DB_PASSWORD@127.0.0.1:5432/${cfg.database.name}"
          export POSTGRES_PASSWORD="$DB_PASSWORD"
          export NODE_PATH=${cfg.package}/node_modules:${cfg.package}/packages/admin-server/node_modules
          cd ${cfg.package}
          exec "$@"
        '';
      in defaultHardening // {
        WorkingDirectory = "${cfg.package}/packages/server";
        ExecStart = "${lamassuAdminEnv} ${pkgs.nodejs_22}/bin/node packages/server/bin/lamassu-admin-server --logLevel ${cfg.logLevel}";
        MemoryDenyWriteExecute = false;
        ReadWritePaths = [ cfg.dataDir cfg.package ];
        User = cfg.user;
        Group = cfg.group;
        Restart = "on-failure";
        RestartSec = "10s";

        # Allow binding to privileged port 443 (production mode)
        AmbientCapabilities = [ "CAP_NET_BIND_SERVICE" ];
        CapabilityBoundingSet = [ "CAP_NET_BIND_SERVICE" ];
      };
    };

    # Open firewall ports
    # Port 3000 (configurable): machine API access (required for pairing and operation)
    # Port 443: admin UI (production mode, hardcoded in upstream)
    networking.firewall.allowedTCPPorts = [ cfg.serverPort 443 ];

    # Add useful packages
    environment.systemPackages = with pkgs; [
      nodejs_22
      nodePackages.pnpm
      postgresql
      (writeShellScriptBin "lamassu-register-user" ''
        # Read database password from nix-bitcoin secrets
        DB_PASSWORD=$(cat ${secretsDir}/lamassu-db-password)
        export NODE_PATH="${cfg.package}/node_modules:${cfg.package}/packages/server/node_modules"
        export DATABASE_URL="postgresql://${cfg.database.user}:$DB_PASSWORD@127.0.0.1:5432/${cfg.database.name}"
        export HOSTNAME="${cfg.hostname}"
        export POSTGRES_HOST="127.0.0.1"
        export POSTGRES_PORT="5432"
        export POSTGRES_DB="${cfg.database.name}"
        export POSTGRES_USER="${cfg.database.user}"
        export POSTGRES_PASSWORD="$DB_PASSWORD"
        export SKIP_2FA="${if cfg.skip2FA then "true" else "false"}"

        sudo -E -u ${cfg.user} bash -c "cd ${cfg.package}/packages/server && ${pkgs.nodejs_22}/bin/node bin/lamassu-register \"\$@\"" -- "$@"
      '')
      (writeShellScriptBin "lamassu-status" ''
        echo "=== Lamassu Server Status ==="
        systemctl status lamassu-server lamassu-admin-server
        echo ""
        echo "=== Database Status ==="
        sudo -u ${cfg.database.user} ${pkgs.postgresql}/bin/psql -d ${cfg.database.name} -c "SELECT version();"
        echo ""
        echo "=== Network Access ==="
        echo "Server API: https://localhost:${toString cfg.serverPort}"
        echo "Admin UI: https://localhost:443"
      '')
    ];
  };
}