import 'package:flutter/material.dart';

enum MasterFieldType { text, number, boolean, dropdown }

const categoryTypeOptions = ['STOCK', 'ASSET'];
const termsNotesTypeOptions = ['PO', 'INVOICE'];

class MasterFieldDef {
  const MasterFieldDef({
    required this.key,
    required this.label,
    this.type = MasterFieldType.text,
    this.required = false,
    this.showInList = false,
    this.showInForm = true,
    this.readOnly = false,
    this.optionsMasterKey,
    this.optionsQueryParams,
    this.staticOptions,
    this.multiline = false,
    this.filterByFieldKey,
    this.filterByOptionKey,
    this.visibleWhenFieldKey,
    this.visibleWhenValue,
    this.listNestedKey,
  });

  final String key;
  final String label;
  final MasterFieldType type;
  final bool required;
  final bool showInList;
  /// When false, field is list/display-only and excluded from create/update payloads.
  final bool showInForm;
  /// When true, shown in the form but not editable (value set by other fields).
  final bool readOnly;
  /// Master key used to populate dropdown options (e.g. `locations` for FKs).
  final String? optionsMasterKey;
  /// Extra query parameters when loading [optionsMasterKey] options.
  final Map<String, dynamic>? optionsQueryParams;
  /// Fixed dropdown choices (e.g. category type) — no API lookup.
  final List<String>? staticOptions;
  final bool multiline;
  /// Form field whose value filters this dropdown (e.g. `item_category_id`).
  final String? filterByFieldKey;
  /// Option-row key matched against [filterByFieldKey] (defaults to same key).
  final String? filterByOptionKey;
  /// Show this field only when [visibleWhenFieldKey] equals [visibleWhenValue].
  final String? visibleWhenFieldKey;
  final String? visibleWhenValue;
  /// Nested object key on list rows for display (e.g. `gst_rate` for `gst_rate_id`).
  final String? listNestedKey;

  /// Cache key for dropdown option rows (includes query params when set).
  String get dropdownLookupKey {
    final masterKey = optionsMasterKey;
    if (masterKey == null) return key;
    final params = optionsQueryParams;
    if (params == null || params.isEmpty) return masterKey;
    final parts = params.entries.toList()
      ..sort((a, b) => a.key.compareTo(b.key));
    final query = parts.map((e) => '${e.key}=${e.value}').join('&');
    return '$masterKey?$query';
  }

  bool isVisibleInForm(Map<String, dynamic> values) {
    final whenKey = visibleWhenFieldKey;
    if (whenKey == null) return true;
    return values[whenKey]?.toString() == visibleWhenValue;
  }
}

class MasterDefinition {
  const MasterDefinition({
    required this.id,
    required this.title,
    required this.subtitle,
    required this.category,
    required this.routeKey,
    required this.apiPath,
    required this.module,
    required this.icon,
    required this.fields,
  });

  final String id;
  final String title;
  final String subtitle;
  final String category;
  final String routeKey;
  final String apiPath;
  final String module;
  final IconData icon;
  final List<MasterFieldDef> fields;

  List<MasterFieldDef> get listFields =>
      fields.where((field) => field.showInList).toList();

  List<MasterFieldDef> get formFields =>
      fields.where((field) => field.showInForm).toList();

  String listRoute(String base) => '$base/$routeKey';
  String addRoute(String base) => '$base/$routeKey/add';
  String editRoute(String base, String id) => '$base/$routeKey/$id/edit';
}

const _activeField = MasterFieldDef(
  key: 'is_active',
  label: 'Active',
  type: MasterFieldType.boolean,
);

MasterDefinition? masterDefinitionById(String id) {
  for (final def in masterDefinitions) {
    if (def.id == id) return def;
  }
  return null;
}

MasterDefinition? masterDefinitionByRouteKey(String routeKey) {
  for (final def in masterDefinitions) {
    if (def.routeKey == routeKey) return def;
  }
  return null;
}

const masterDefinitions = <MasterDefinition>[
  MasterDefinition(
    id: 'uom',
    title: 'UOM',
    subtitle: 'Units of measure',
    category: 'Inventory & Items',
    routeKey: 'uom',
    apiPath: '/masters/uom',
    module: 'uom',
    icon: Icons.straighten_outlined,
    fields: [
      MasterFieldDef(key: 'code', label: 'Code', required: true, showInList: true),
      MasterFieldDef(key: 'name', label: 'Name', required: true, showInList: true),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'item_categories',
    title: 'Item Categories',
    subtitle: 'Top-level item grouping',
    category: 'Inventory & Items',
    routeKey: 'item-categories',
    apiPath: '/masters/item-categories',
    module: 'item_categories',
    icon: Icons.category_outlined,
    fields: [
      MasterFieldDef(key: 'code', label: 'Code', required: true, showInList: true),
      MasterFieldDef(key: 'name', label: 'Name', required: true, showInList: true),
      MasterFieldDef(
        key: 'category_type',
        label: 'Category Type',
        type: MasterFieldType.dropdown,
        required: true,
        showInList: true,
        staticOptions: categoryTypeOptions,
      ),
      MasterFieldDef(
        key: 'code_prefix',
        label: 'Code Prefix',
        showInList: true,
        visibleWhenFieldKey: 'category_type',
        visibleWhenValue: 'ASSET',
      ),
      MasterFieldDef(
        key: 'default_useful_life_years',
        label: 'Useful Life (Years)',
        type: MasterFieldType.number,
        visibleWhenFieldKey: 'category_type',
        visibleWhenValue: 'ASSET',
      ),
      MasterFieldDef(
        key: 'default_depreciation_method',
        label: 'Depreciation Method',
        type: MasterFieldType.dropdown,
        showInList: true,
        optionsMasterKey: 'asset_depreciation_methods',
        visibleWhenFieldKey: 'category_type',
        visibleWhenValue: 'ASSET',
      ),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'item_subcategories',
    title: 'Item Sub Categories',
    subtitle: 'Sub-grouping under item categories',
    category: 'Inventory & Items',
    routeKey: 'item-subcategories',
    apiPath: '/masters/item-subcategories',
    module: 'item_subcategories',
    icon: Icons.subdirectory_arrow_right,
    fields: [
      MasterFieldDef(
        key: 'item_category_id',
        label: 'Item Category',
        type: MasterFieldType.dropdown,
        required: true,
        showInList: true,
        optionsMasterKey: 'item_categories',
      ),
      MasterFieldDef(key: 'code', label: 'Code', required: true, showInList: true),
      MasterFieldDef(key: 'name', label: 'Name', required: true, showInList: true),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'items',
    title: 'Items',
    subtitle: 'Material and product master',
    category: 'Inventory & Items',
    routeKey: 'items',
    apiPath: '/masters/items',
    module: 'items',
    icon: Icons.inventory_outlined,
    fields: [
      // Auto-generated by backend — list only; never sent on create/update.
      MasterFieldDef(
        key: 'item_code',
        label: 'Item Code',
        showInList: true,
        showInForm: false,
      ),
      MasterFieldDef(key: 'item_name', label: 'Item Name', required: true, showInList: true),
      MasterFieldDef(
        key: 'is_asset_item',
        label: 'Asset Item',
        type: MasterFieldType.boolean,
        required: true,
        showInList: true,
      ),
      MasterFieldDef(
        key: 'item_category_id',
        label: 'Category',
        type: MasterFieldType.dropdown,
        required: true,
        optionsMasterKey: 'item_categories',
        // Resolved at runtime from is_asset_item (STOCK / ASSET).
      ),
      MasterFieldDef(
        key: 'item_subcategory_id',
        label: 'Sub Category',
        type: MasterFieldType.dropdown,
        optionsMasterKey: 'item_subcategories',
        filterByFieldKey: 'item_category_id',
      ),
      MasterFieldDef(
        key: 'uom_id',
        label: 'UOM',
        type: MasterFieldType.dropdown,
        required: true,
        optionsMasterKey: 'uom',
      ),
      MasterFieldDef(
        key: 'hsn_code_id',
        label: 'HSN Code',
        type: MasterFieldType.dropdown,
        showInList: true,
        optionsMasterKey: 'hsn_codes',
      ),
      MasterFieldDef(
        key: 'gst_rate_id',
        label: 'GST Rate',
        type: MasterFieldType.dropdown,
        showInList: true,
        readOnly: true,
        // Filled from selected HSN's nested gst_rate — no gst-rates API.
      ),
      MasterFieldDef(
        key: 'min_order_qty',
        label: 'Min Order Qty',
        type: MasterFieldType.number,
        required: true,
        // Stock items only — hidden when Asset Item is checked.
        visibleWhenFieldKey: 'is_asset_item',
        visibleWhenValue: 'false',
      ),
      MasterFieldDef(
        key: 'reorder_level',
        label: 'Reorder Level',
        type: MasterFieldType.number,
        required: true,
        visibleWhenFieldKey: 'is_asset_item',
        visibleWhenValue: 'false',
      ),
      MasterFieldDef(
        key: 'tags',
        label: 'Tags',
        multiline: true,
        showInList: true,
      ),
      MasterFieldDef(key: 'description', label: 'Description', multiline: true),
      MasterFieldDef(key: 'specification', label: 'Specification', multiline: true),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'hsn_codes',
    title: 'HSN Codes',
    subtitle: 'HSN/SAC tax classification codes',
    category: 'Finance & Terms',
    routeKey: 'hsn-codes',
    apiPath: '/masters/hsn-codes',
    module: 'hsn_codes',
    icon: Icons.qr_code_outlined,
    fields: [
      MasterFieldDef(key: 'code', label: 'HSN/SAC Code', required: true, showInList: true),
      MasterFieldDef(
        key: 'description',
        label: 'Description',
        required: true,
        showInList: true,
        multiline: true,
      ),
      MasterFieldDef(
        key: 'gst_rate_id',
        label: 'GST Rate',
        type: MasterFieldType.dropdown,
        showInList: true,
        optionsMasterKey: 'gst_rates',
      ),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'document_series',
    title: 'Document Series',
    subtitle: 'Numbering series for documents',
    category: 'Finance & Terms',
    routeKey: 'document-series',
    apiPath: '/masters/document-series',
    module: 'document_series',
    icon: Icons.numbers_outlined,
    fields: [
      MasterFieldDef(key: 'code', label: 'Code', required: true, showInList: true),
      MasterFieldDef(key: 'prefix', label: 'Prefix', required: true, showInList: true),
      MasterFieldDef(
        key: 'current_number',
        label: 'Current Number',
        type: MasterFieldType.number,
        required: true,
        showInList: true,
      ),
      MasterFieldDef(
        key: 'padding',
        label: 'Padding',
        type: MasterFieldType.number,
        required: true,
      ),
      MasterFieldDef(key: 'description', label: 'Description', multiline: true),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'locations',
    title: 'Locations',
    subtitle: 'Plants and warehouses',
    category: 'Organization',
    routeKey: 'locations',
    apiPath: '/masters/locations',
    module: 'locations',
    icon: Icons.place_outlined,
    fields: [
      MasterFieldDef(
        key: 'type',
        label: 'Type',
        type: MasterFieldType.dropdown,
        required: true,
        showInList: true,
        staticOptions: const ['plant', 'warehouse'],
      ),
      MasterFieldDef(key: 'code', label: 'Code', required: true, showInList: true),
      MasterFieldDef(key: 'name', label: 'Name', required: true, showInList: true),
      MasterFieldDef(
        key: 'gstin',
        label: 'GSTIN',
        showInList: true,
        visibleWhenFieldKey: 'type',
        visibleWhenValue: 'plant',
      ),
      MasterFieldDef(
        key: 'city',
        label: 'City',
        showInList: true,
        visibleWhenFieldKey: 'type',
        visibleWhenValue: 'plant',
      ),
      MasterFieldDef(
        key: 'state',
        label: 'State',
        type: MasterFieldType.dropdown,
        optionsMasterKey: 'location_states',
        showInList: true,
        visibleWhenFieldKey: 'type',
        visibleWhenValue: 'plant',
      ),
      MasterFieldDef(
        key: 'address',
        label: 'Address',
        multiline: true,
        visibleWhenFieldKey: 'type',
        visibleWhenValue: 'plant',
      ),
      MasterFieldDef(
        key: 'pincode',
        label: 'Pincode',
        visibleWhenFieldKey: 'type',
        visibleWhenValue: 'plant',
      ),
      MasterFieldDef(
        key: 'phone',
        label: 'Phone',
        visibleWhenFieldKey: 'type',
        visibleWhenValue: 'plant',
      ),
      MasterFieldDef(
        key: 'location',
        label: 'Location Detail',
        showInList: true,
        visibleWhenFieldKey: 'type',
        visibleWhenValue: 'warehouse',
      ),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'designations',
    title: 'Designations',
    subtitle: 'Employee designations',
    category: 'Organization',
    routeKey: 'designations',
    apiPath: '/masters/designations',
    module: 'designations',
    icon: Icons.badge_outlined,
    fields: [
      MasterFieldDef(key: 'name', label: 'Name', required: true, showInList: true),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'departments',
    title: 'Departments',
    subtitle: 'Organisation departments',
    category: 'Organization',
    routeKey: 'departments',
    apiPath: '/masters/departments',
    module: 'departments',
    icon: Icons.apartment_outlined,
    fields: [
      MasterFieldDef(key: 'name', label: 'Name', required: true, showInList: true),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'delivery_terms',
    title: 'Delivery Terms',
    subtitle: 'Delivery incoterms and terms',
    category: 'Finance & Terms',
    routeKey: 'delivery-terms',
    apiPath: '/masters/delivery-terms',
    module: 'delivery_terms',
    icon: Icons.local_shipping_outlined,
    fields: [
      MasterFieldDef(key: 'code', label: 'Code', required: true, showInList: true),
      MasterFieldDef(key: 'name', label: 'Name', required: true, showInList: true),
      MasterFieldDef(key: 'description', label: 'Description', multiline: true),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'payment_terms',
    title: 'Payment Terms',
    subtitle: 'Vendor payment terms',
    category: 'Finance & Terms',
    routeKey: 'payment-terms',
    apiPath: '/masters/payment-terms',
    module: 'payment_terms',
    icon: Icons.payments_outlined,
    fields: [
      MasterFieldDef(key: 'code', label: 'Code', required: true, showInList: true),
      MasterFieldDef(key: 'name', label: 'Name', required: true, showInList: true),
      MasterFieldDef(
        key: 'credit_days',
        label: 'Credit Days',
        type: MasterFieldType.number,
        required: true,
        showInList: true,
      ),
      MasterFieldDef(key: 'description', label: 'Description', multiline: true),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'terms_notes',
    title: 'Terms & Notes',
    subtitle: 'Default terms by document type (PO, Invoice)',
    category: 'Finance & Terms',
    routeKey: 'terms-notes',
    apiPath: '/masters/terms-notes',
    module: 'terms_notes',
    icon: Icons.notes_outlined,
    fields: [
      MasterFieldDef(
        key: 'type',
        label: 'Document Type',
        type: MasterFieldType.dropdown,
        required: true,
        showInList: true,
        staticOptions: termsNotesTypeOptions,
      ),
      MasterFieldDef(
        key: 'notes',
        label: 'Notes',
        required: true,
        showInList: true,
        multiline: true,
      ),
      _activeField,
    ],
  ),
  MasterDefinition(
    id: 'gst_rates',
    title: 'GST Rates',
    subtitle: 'Tax rate master',
    category: 'Finance & Terms',
    routeKey: 'gst-rates',
    apiPath: '/masters/gst-rates',
    module: 'gst_rates',
    icon: Icons.percent_outlined,
    fields: [
      MasterFieldDef(
        key: 'rate_pct',
        label: 'Rate (%)',
        type: MasterFieldType.number,
        required: true,
        showInList: true,
      ),
      MasterFieldDef(key: 'description', label: 'Description', showInList: true),
      _activeField,
    ],
  ),
];

List<String> get masterCategories =>
    masterDefinitions.map((def) => def.category).toSet().toList();

String masterRecordLabel(Map<String, dynamic> row) {
  final ratePct = row['rate_pct'];
  if (ratePct != null) {
    final rate = ratePct is num
        ? ratePct.toDouble()
        : double.tryParse(ratePct.toString());
    if (rate != null) {
      final rateLabel = rate % 1 == 0 ? '${rate.toInt()}%' : '$rate%';
      final desc = row['description'];
      if (desc != null && desc.toString().trim().isNotEmpty) {
        return '$rateLabel — ${desc.toString().trim()}';
      }
      return rateLabel;
    }
  }

  for (final key in ['name', 'item_name', 'item_code']) {
    final value = row[key];
    if (value != null && value.toString().trim().isNotEmpty) {
      return value.toString();
    }
  }

  final code = row['code'];
  if (code != null && code.toString().trim().isNotEmpty) {
    final desc = row['description'];
    if (desc != null && desc.toString().trim().isNotEmpty) {
      return '${code.toString().trim()} — ${desc.toString().trim()}';
    }
    return code.toString().trim();
  }

  final description = row['description'];
  if (description != null && description.toString().trim().isNotEmpty) {
    return description.toString().trim();
  }
  return row['id']?.toString() ?? 'Record';
}

String masterCellValue(Map<String, dynamic> row, MasterFieldDef field) {
  final value = row[field.key];
  if (value == null || value == '') return '—';

  if (field.key == 'is_asset_item') {
    return masterIsAssetItem(value) ? 'Asset' : 'Stock';
  }

  if (field.key == 'tags') {
    if (value is List) {
      final tags = value
          .map((e) => e.toString().trim())
          .where((e) => e.isNotEmpty)
          .toList();
      return tags.isEmpty ? '—' : tags.join(', ');
    }
    final text = value.toString().trim();
    return text.isEmpty ? '—' : text;
  }

  if (field.type == MasterFieldType.boolean) {
    return value == true ? 'Yes' : 'No';
  }

  if (field.type == MasterFieldType.dropdown) {
    final label = row['${field.key}_label'];
    if (label != null && label.toString().isNotEmpty) return label.toString();

    if (field.key == 'gst_rate_id') {
      final nested = row['gst_rate'];
      if (nested is Map) {
        final pct = nested['rate_pct'];
        if (pct != null) {
          final rate = pct is num
              ? pct.toDouble()
              : double.tryParse(pct.toString());
          if (rate != null) {
            return rate % 1 == 0 ? '${rate.toInt()}%' : '$rate%';
          }
        }
      }
    }

    // Prefer explicit "<base>_name" or nested "<base>.name" / flat code from API
    // (e.g. asset_category_id -> asset_category_name; hsn_code_id -> hsn_code)
    if (field.key.endsWith('_id')) {
      final baseKey = field.key.substring(0, field.key.length - 3);
      final explicitName = row['${baseKey}_name'];
      if (explicitName != null && explicitName.toString().trim().isNotEmpty) {
        return explicitName.toString().trim();
      }

      final nestedKeys = <String>[
        if (field.listNestedKey != null) field.listNestedKey!,
        baseKey,
      ];
      for (final nestedKey in nestedKeys) {
        final nested = row[nestedKey];
        if (nested is Map) {
          for (final nameKey in ['name', 'code', 'description']) {
            final nestedValue = nested[nameKey];
            if (nestedValue != null &&
                nestedValue.toString().trim().isNotEmpty) {
              return nestedValue.toString().trim();
            }
          }
        } else if (nested != null && nested.toString().trim().isNotEmpty) {
          // Flat denormalized value (e.g. items.hsn_code string)
          return nested.toString().trim();
        }
      }
    }

    if (field.staticOptions != null) {
      return value.toString().replaceAll('_', ' ');
    }
  }

  return value.toString();
}

String masterStatusValue(Map<String, dynamic> row) {
  final active = row['is_active'];
  if (active == false) return 'inactive';
  return 'active';
}

bool masterIsAssetItem(Object? value) {
  if (value == true || value == 1) return true;
  if (value == false || value == 0) return false;
  final text = value?.toString().trim().toLowerCase() ?? '';
  return text == 'true' || text == '1' || text == 'yes';
}

/// Category list filter for Items form: ASSET when Asset Item is checked.
String itemCategoryTypeForValues(Map<String, dynamic> values) =>
    values['is_asset_item'] == true ? 'ASSET' : 'STOCK';

/// Effective options query for a form field (may depend on other values).
Map<String, dynamic>? masterFieldOptionsQuery({
  required String masterId,
  required MasterFieldDef field,
  required Map<String, dynamic> values,
}) {
  if (masterId == 'items' && field.key == 'item_category_id') {
    return {'category_type': itemCategoryTypeForValues(values)};
  }
  return field.optionsQueryParams;
}

String masterFieldDropdownLookupKey({
  required String masterId,
  required MasterFieldDef field,
  required Map<String, dynamic> values,
}) {
  final masterKey = field.optionsMasterKey;
  if (masterKey == null) return field.key;
  final params = masterFieldOptionsQuery(
    masterId: masterId,
    field: field,
    values: values,
  );
  if (params == null || params.isEmpty) return masterKey;
  final parts = params.entries.toList()
    ..sort((a, b) => a.key.compareTo(b.key));
  final query = parts.map((e) => '${e.key}=${e.value}').join('&');
  return '$masterKey?$query';
}

/// Placeholder / hint casing for master field labels (keeps UOM, HSN, GST, etc.).
String masterFieldHintLabel(String label) {
  const acronyms = {
    'uom': 'UOM',
    'hsn': 'HSN',
    'gst': 'GST',
    'sac': 'SAC',
    'po': 'PO',
    'grn': 'Purchase Receipt',
    'amc': 'AMC',
  };
  return label
      .trim()
      .split(RegExp(r'\s+'))
      .where((part) => part.isNotEmpty)
      .map((part) {
        final lower = part.toLowerCase();
        return acronyms[lower] ?? lower;
      })
      .join(' ');
}

/// Display label for GST filled from HSN nested `gst_rate.description`.
String? gstRateDisplayFromValues(Map<String, dynamic> values) {
  final nested = values['gst_rate'];
  if (nested is Map) {
    final desc = nested['description'];
    if (desc != null && desc.toString().trim().isNotEmpty) {
      return desc.toString().trim();
    }
    final pct = nested['rate_pct'];
    if (pct != null) {
      final rate = pct is num ? pct.toDouble() : double.tryParse(pct.toString());
      if (rate != null) {
        return rate % 1 == 0 ? '${rate.toInt()}%' : '$rate%';
      }
    }
  }
  final label = values['gst_rate_label'];
  if (label != null && label.toString().trim().isNotEmpty) {
    return label.toString().trim();
  }
  return null;
}