import 'package:flutter/material.dart';

/// RBAC permission actions shown in the permission matrix.
enum RbacAction {
  read('read', 'VIEW'),
  create('create', 'CREATE'),
  update('update', 'EDIT'),
  delete('delete', 'DELETE'),
  approve('approve', 'APPROVE'),
  export('export', 'EXPORT');

  const RbacAction(this.value, this.label);
  final String value;
  final String label;
}

/// Modules available in the permission matrix.
class RbacModule {
  const RbacModule({
    required this.key,
    required this.label,
    required this.icon,
    required this.color,
  });

  final String key;
  final String label;
  final IconData icon;
  final Color color;
}

const rbacModules = [
  RbacModule(
    key: 'users',
    label: 'User Management',
    icon: Icons.people_outline,
    color: Color(0xFF2563EB),
  ),
  RbacModule(
    key: 'roles',
    label: 'Roles & Permissions',
    icon: Icons.shield_outlined,
    color: Color(0xFF16A34A),
  ),
  RbacModule(
    key: 'masters',
    label: 'Master Data',
    icon: Icons.dataset_outlined,
    color: Color(0xFFEA580C),
  ),
  RbacModule(
    key: 'vendors',
    label: 'Vendor Management',
    icon: Icons.storefront_outlined,
    color: Color(0xFF7C3AED),
  ),
  RbacModule(
    key: 'purchase_orders',
    label: 'Purchase Orders',
    icon: Icons.receipt_long_outlined,
    color: Color(0xFFCA8A04),
  ),
  RbacModule(
    key: 'grn',
    label: 'Purchase Receipt',
    icon: Icons.inventory_outlined,
    color: Color(0xFF0891B2),
  ),
  RbacModule(
    key: 'assets',
    label: 'Asset Management',
    icon: Icons.inventory_2_outlined,
    color: Color(0xFFDC2626),
  ),
];

class ManagedUser {
  const ManagedUser({
    required this.id,
    required this.name,
    required this.email,
    required this.employeeCode,
    required this.roleId,
    required this.roleName,
    required this.department,
    required this.plant,
    required this.lastLogin,
    required this.status,
  });

  final String id;
  final String name;
  final String email;
  final String employeeCode;
  final String roleId;
  final String roleName;
  final String department;
  final String plant;
  final String lastLogin;
  final UserAccountStatus status;

  String get initials {
    final parts = name.trim().split(RegExp(r'\s+'));
    if (parts.length >= 2) {
      return '${parts.first[0]}${parts[1][0]}'.toUpperCase();
    }
    return name.isNotEmpty ? name[0].toUpperCase() : 'U';
  }

  ManagedUser copyWith({
    String? id,
    String? name,
    String? email,
    String? employeeCode,
    String? roleId,
    String? roleName,
    String? department,
    String? plant,
    String? lastLogin,
    UserAccountStatus? status,
  }) {
    return ManagedUser(
      id: id ?? this.id,
      name: name ?? this.name,
      email: email ?? this.email,
      employeeCode: employeeCode ?? this.employeeCode,
      roleId: roleId ?? this.roleId,
      roleName: roleName ?? this.roleName,
      department: department ?? this.department,
      plant: plant ?? this.plant,
      lastLogin: lastLogin ?? this.lastLogin,
      status: status ?? this.status,
    );
  }
}

enum UserAccountStatus {
  active('Active', Color(0xFF16A34A)),
  inactive('Inactive', Color(0xFF6B7280)),
  locked('Locked', Color(0xFFDC2626));

  const UserAccountStatus(this.label, this.color);
  final String label;
  final Color color;
}

UserAccountStatus userStatusFromApi(String status) => switch (status.toLowerCase()) {
      'active' => UserAccountStatus.active,
      'inactive' => UserAccountStatus.inactive,
      'locked' => UserAccountStatus.locked,
      _ => UserAccountStatus.inactive,
    };

class ManagedRole {
  const ManagedRole({
    required this.id,
    required this.name,
    required this.description,
    required this.icon,
    required this.color,
    required this.userCount,
    required this.permissions,
  });

  final String id;
  final String name;
  final String description;
  final IconData icon;
  final Color color;
  final int userCount;
  final Set<String> permissions;

  int get permissionCount => permissions.length;

  ManagedRole copyWith({
    String? id,
    String? name,
    String? description,
    IconData? icon,
    Color? color,
    int? userCount,
    Set<String>? permissions,
  }) {
    return ManagedRole(
      id: id ?? this.id,
      name: name ?? this.name,
      description: description ?? this.description,
      icon: icon ?? this.icon,
      color: color ?? this.color,
      userCount: userCount ?? this.userCount,
      permissions: permissions ?? this.permissions,
    );
  }

  bool hasPermission(String module, RbacAction action) =>
      permissions.contains('$module.${action.value}');
}

String permissionKey(String module, RbacAction action) =>
    '$module.${action.value}';

Set<String> allPermissionsForRole(String roleId) {
  final all = <String>{};
  for (final module in rbacModules) {
    for (final action in RbacAction.values) {
      all.add(permissionKey(module.key, action));
    }
  }

  Set<String> modulePerms(
    String module, {
    bool create = false,
    bool edit = false,
    bool delete = false,
    bool approve = false,
    bool export = false,
    bool view = true,
  }) {
    final perms = <String>{};
    if (view) perms.add(permissionKey(module, RbacAction.read));
    if (create) perms.add(permissionKey(module, RbacAction.create));
    if (edit) perms.add(permissionKey(module, RbacAction.update));
    if (delete) perms.add(permissionKey(module, RbacAction.delete));
    if (approve) perms.add(permissionKey(module, RbacAction.approve));
    if (export) perms.add(permissionKey(module, RbacAction.export));
    return perms;
  }

  return switch (roleId) {
    'super_admin' => all,
    'admin' => all.where((p) => !p.startsWith('settings.')).toSet(),
    'purchase_manager' => {
      ...modulePerms('users', view: true),
      ...modulePerms('masters', view: true, create: true, edit: true),
      ...modulePerms('vendors', view: true, create: true, edit: true),
      ...modulePerms('purchase_orders',
          view: true, create: true, edit: true, approve: true, export: true),
      ...modulePerms('grn', view: true),
      ...modulePerms('assets', view: true),
    },
    'store_manager' => {
      ...modulePerms('masters', view: true),
      ...modulePerms('grn', view: true, create: true, edit: true),
      ...modulePerms('assets', view: true),
    },
    'accounts' => {
      ...modulePerms('vendors', view: true),
      ...modulePerms('purchase_orders', view: true, export: true),
      ...modulePerms('grn', view: true),
    },
    'asset_manager' => {
      ...modulePerms('assets',
          view: true, create: true, edit: true, delete: true, export: true),
      ...modulePerms('masters', view: true),
    },
    _ => {permissionKey('assets', RbacAction.read)},
  };
}

List<ManagedRole> defaultRoles = [
  ManagedRole(
    id: 'super_admin',
    name: 'Super Admin',
    description: 'Full access to all modules',
    icon: Icons.admin_panel_settings_outlined,
    color: const Color(0xFF2563EB),
    userCount: 1,
    permissions: allPermissionsForRole('super_admin'),
  ),
  ManagedRole(
    id: 'admin',
    name: 'Admin',
    description: 'Administrative access, no system config',
    icon: Icons.shield_outlined,
    color: const Color(0xFF16A34A),
    userCount: 2,
    permissions: allPermissionsForRole('admin'),
  ),
  ManagedRole(
    id: 'purchase_manager',
    name: 'Purchase Manager',
    description: 'Full PO lifecycle and vendor management',
    icon: Icons.receipt_long_outlined,
    color: const Color(0xFFCA8A04),
    userCount: 8,
    permissions: allPermissionsForRole('purchase_manager'),
  ),
  ManagedRole(
    id: 'store_manager',
    name: 'Store Manager',
    description: 'Purchase Receipt, warehouse receipts, stock view',
    icon: Icons.warehouse_outlined,
    color: const Color(0xFF0891B2),
    userCount: 12,
    permissions: allPermissionsForRole('store_manager'),
  ),
  ManagedRole(
    id: 'accounts',
    name: 'Accounts',
    description: 'View PO, Purchase Receipt, vendor financial details',
    icon: Icons.account_balance_wallet_outlined,
    color: const Color(0xFF7C3AED),
    userCount: 8,
    permissions: allPermissionsForRole('accounts'),
  ),
  ManagedRole(
    id: 'asset_manager',
    name: 'Asset Manager',
    description: 'Full asset register and transfer mgmt',
    icon: Icons.inventory_2_outlined,
    color: const Color(0xFFEA580C),
    userCount: 4,
    permissions: allPermissionsForRole('asset_manager'),
  ),
];

List<ManagedUser> buildDefaultUsers() {
  const seeds = [
    ('Gowtham S', 'gowtham@bharaterp.com', 'super_admin', 'Super Admin',
        'Administration', 'Unit 1 - Soap', 'Today 10:24 AM', UserAccountStatus.active),
    ('Ravi Kumar', 'ravi@bharaterp.com', 'purchase_manager', 'Purchase Manager',
        'Procurement', 'Unit 1 - Soap', 'Yesterday', UserAccountStatus.active),
    ('Priya Sharma', 'priya@bharaterp.com', 'store_manager', 'Store Manager',
        'Stores / Warehouse', 'Unit 2 - Powder', '2 days ago', UserAccountStatus.active),
    ('Anil Mehta', 'anil@bharaterp.com', 'accounts', 'Accounts',
        'Finance', 'Unit 1 - Soap', '1 week ago', UserAccountStatus.inactive),
    ('Deepak Singh', 'deepak@bharaterp.com', 'asset_manager', 'Asset Manager',
        'Asset Management', 'Unit 1 - Soap', '3 days ago', UserAccountStatus.locked),
  ];

  final users = <ManagedUser>[];
  final roleIds = [
    'purchase_manager',
    'store_manager',
    'accounts',
    'asset_manager',
    'admin',
  ];
  final roleNames = {
    'purchase_manager': 'Purchase Manager',
    'store_manager': 'Store Manager',
    'accounts': 'Accounts',
    'asset_manager': 'Asset Manager',
    'admin': 'Admin',
  };
  final departments = [
    'Procurement',
    'Stores / Warehouse',
    'Finance',
    'Asset Management',
    'Administration',
    'Production',
  ];
  final plants = ['Unit 1 - Soap', 'Unit 2 - Powder', 'Head Office'];
  final logins = ['Today 09:15 AM', 'Yesterday', '2 days ago', '3 days ago', '1 week ago'];
  final statuses = [
    UserAccountStatus.active,
    UserAccountStatus.active,
    UserAccountStatus.active,
    UserAccountStatus.inactive,
    UserAccountStatus.locked,
  ];

  for (var i = 0; i < 38; i++) {
    if (i < seeds.length) {
      final s = seeds[i];
      users.add(
        ManagedUser(
          id: '${i + 1}',
          name: s.$1,
          email: s.$2,
          employeeCode: 'EMP-${(i + 1).toString().padLeft(3, '0')}',
          roleId: s.$3,
          roleName: s.$4,
          department: s.$5,
          plant: s.$6,
          lastLogin: s.$7,
          status: s.$8,
        ),
      );
      continue;
    }

    final roleId = roleIds[i % roleIds.length];
    users.add(
      ManagedUser(
        id: '${i + 1}',
        name: 'User ${i + 1}',
        email: 'user${i + 1}@bharaterp.com',
        employeeCode: 'EMP-${(i + 1).toString().padLeft(3, '0')}',
        roleId: roleId,
        roleName: roleNames[roleId]!,
        department: departments[i % departments.length],
        plant: plants[i % plants.length],
        lastLogin: logins[i % logins.length],
        status: statuses[i % statuses.length],
      ),
    );
  }

  return users;
}

List<ManagedUser> get defaultUsers => buildDefaultUsers();