import type {
  DataServiceCollectionRemoval,
  DataServiceDocument,
  DataServiceDocumentList,
  DataServiceErrorContext,
  DataServiceHostResult,
  DataServiceInstanceList,
  DataServiceInstanceRemoval,
  DataServiceInstanceState,
} from '../../../shared/data-service';
import {
  DATA_SERVICE_PLUGIN_ID,
  type CodingPluginToolDefinition,
} from '../../../shared/coding-plugins';
import type { DataServiceOperations } from '../../services/data-service-client';
import type {
  AdapterInvocationResult,
  CodingPluginAdapter,
  PluginBackendProjection,
  TrustedCodingCapabilityContext,
} from '../registry';

const MAX_REQUEST_BYTES = 98_304;
const CONTEXT_KEYS = new Set([
  'resource', 'limit', 'current', 'attempted', 'actual', 'current_revision',
]);
const CONTEXT_RESOURCES = new Set(['instances', 'collections', 'documents', 'bytes']);

type InputRecord = Record<string, unknown>;

function isRecord(value: unknown): value is InputRecord {
  return value !== null && typeof value === 'object' && !Array.isArray(value);
}

function boundedContext(value: DataServiceErrorContext | undefined): DataServiceErrorContext | undefined {
  if (!value) return undefined;
  const projected: DataServiceErrorContext = {};
  for (const [key, item] of Object.entries(value)) {
    if (!CONTEXT_KEYS.has(key)) continue;
    if (key === 'resource') {
      if (typeof item !== 'string' || !CONTEXT_RESOURCES.has(item) || item.length > 32) return undefined;
      projected[key] = item;
    } else if (Number.isSafeInteger(item) && (item as number) >= 0) {
      projected[key] = item as number;
    }
  }
  return Object.keys(projected).length > 0 ? projected : undefined;
}

function validRetryAfter(value: unknown): value is number {
  return Number.isSafeInteger(value) && (value as number) >= 0 && (value as number) <= 86_400;
}

function boundedError(error: unknown, fallback: string): string {
  return typeof error === 'string' && error.trim().length > 0 && error.length <= 2_000
    ? error
    : fallback;
}

function failure(
  code: string,
  error: string,
  status = 422,
  retryable = false,
): AdapterInvocationResult {
  return {
    success: false,
    status,
    code,
    error,
    retryable,
    payload_schema: 'data-service.v1',
    data: null,
  };
}

function projectResult<T>(result: DataServiceHostResult<T>): AdapterInvocationResult<T> {
  if (result.success) {
    return {
      success: true,
      status: result.status,
      code: null,
      error: null,
      retryable: false,
      payload_schema: 'data-service.v1',
      data: result.data,
    };
  }
  const context = boundedContext(result.context);
  return {
    success: false,
    status: result.status,
    code: result.code ?? 'plugin_backend_unavailable',
    error: boundedError(result.error, 'Data Service request was rejected'),
    retryable: result.retryable,
    ...(validRetryAfter(result.retry_after_seconds)
      ? { retry_after_seconds: result.retry_after_seconds }
      : {}),
    ...(context ? { context } : {}),
    payload_schema: 'data-service.v1',
    data: null,
  };
}

function schemaValid(value: unknown, schema: Readonly<Record<string, unknown>>): boolean {
  if (schema.type === 'object') {
    if (!isRecord(value)) return false;
    const properties = isRecord(schema.properties) ? schema.properties : {};
    if (schema.additionalProperties === false
      && Object.keys(value).some((key) => !Object.prototype.hasOwnProperty.call(properties, key))) {
      return false;
    }
    const required = Array.isArray(schema.required) ? schema.required : [];
    if (required.some((key) => typeof key !== 'string' || !Object.prototype.hasOwnProperty.call(value, key))) {
      return false;
    }
    return Object.entries(value).every(([key, item]) => {
      const child = properties[key];
      return !child || (isRecord(child) && schemaValid(item, child));
    });
  }
  if (schema.type === 'array') {
    if (!Array.isArray(value)) return false;
    if (typeof schema.maxItems === 'number' && value.length > schema.maxItems) return false;
    const items = isRecord(schema.items) ? schema.items : null;
    return !items || value.every((item) => schemaValid(item, items));
  }
  if (schema.type === 'string') {
    if (typeof value !== 'string') return false;
    if (typeof schema.minLength === 'number' && value.length < schema.minLength) return false;
    if (typeof schema.maxLength === 'number' && value.length > schema.maxLength) return false;
    if (typeof schema.pattern === 'string' && !(new RegExp(schema.pattern, 'u')).test(value)) return false;
    return true;
  }
  if (schema.type === 'integer') {
    if (!Number.isSafeInteger(value)) return false;
    if (typeof schema.minimum === 'number' && (value as number) < schema.minimum) return false;
    if (typeof schema.maximum === 'number' && (value as number) > schema.maximum) return false;
    return true;
  }
  if (schema.type === 'boolean') return typeof value === 'boolean'
    && (schema.const === undefined || value === schema.const);
  return true;
}

function boundedDocumentData(value: unknown): boolean {
  if (!isRecord(value)) return false;
  try {
    const encoded = JSON.stringify({ data: value });
    return typeof encoded === 'string' && Buffer.byteLength(encoded, 'utf8') <= MAX_REQUEST_BYTES;
  } catch {
    return false;
  }
}

function validateInput(tool: CodingPluginToolDefinition, input: unknown): boolean {
  if (!schemaValid(input, tool.inputSchema)) return false;
  if (!isRecord(input)) return false;
  if (tool.name === 'data_service_put_document' && !boundedDocumentData(input.data)) return false;
  return true;
}

type DataServiceResult =
  | DataServiceInstanceState
  | DataServiceInstanceList
  | DataServiceDocument
  | DataServiceDocumentList
  | DataServiceCollectionRemoval
  | DataServiceInstanceRemoval
  | null;

async function callDataService(
  operations: DataServiceOperations,
  toolName: string,
  input: InputRecord,
  projectPath: string,
): Promise<DataServiceHostResult<DataServiceResult>> {
  switch (toolName) {
    case 'data_service_configure':
      return await operations.configure({ collections: input.collections as string[] }, projectPath);
    case 'data_service_inspect':
      return await operations.inspect(projectPath);
    case 'data_service_list_projects':
      return await operations.listProjects();
    case 'data_service_get_document':
      return await operations.getDocument({
        collection: input.collection as string,
        document_id: input.document_id as string,
      }, projectPath);
    case 'data_service_list_documents':
      return await operations.listDocuments({
        collection: input.collection as string,
        ...(input.limit === undefined ? {} : { limit: input.limit as number }),
        ...(input.cursor === undefined ? {} : { cursor: input.cursor as string }),
      }, projectPath);
    case 'data_service_put_document':
      return await operations.putDocument({
        collection: input.collection as string,
        document_id: input.document_id as string,
        data: input.data as Record<string, unknown>,
        ...(input.if_revision === undefined ? {} : { if_revision: input.if_revision as number }),
      }, projectPath);
    case 'data_service_delete_document':
      return await operations.deleteDocument({
        collection: input.collection as string,
        document_id: input.document_id as string,
        ...(input.if_revision === undefined ? {} : { if_revision: input.if_revision as number }),
        confirmed: true,
      }, projectPath);
    case 'data_service_remove_collection':
      return await operations.removeCollection({
        collection: input.collection as string,
        confirmed: true,
      }, projectPath);
    case 'data_service_reset':
      return await operations.reset({ confirmed: true }, projectPath);
    case 'data_service_remove_project':
      return await operations.removeProject({ confirmed: true }, projectPath);
    default:
      throw new Error('Data Service tool is unavailable');
  }
}

function projection(result: DataServiceHostResult<unknown>): PluginBackendProjection {
  if (result.success) return { status: 'ready' };
  switch (result.code) {
    case 'authentication_required': return { status: 'authentication_required' };
    case 'project_identity_required': return { status: 'identity_required' };
    case 'active_project_required':
    case 'instance_not_found': return { status: 'unconfigured' };
    case 'active_project_path_mismatch':
    case 'active_project_invalid': return { status: 'degraded', code: result.code, message: 'Data Service project is unavailable', retryable: false };
    default:
      return {
        status: 'degraded',
        code: result.code ?? 'plugin_backend_unavailable',
        message: 'Data Service is temporarily unavailable',
        retryable: result.retryable,
        ...(validRetryAfter(result.retry_after_seconds)
          ? { retry_after_seconds: result.retry_after_seconds }
          : {}),
      };
  }
}

export class DataServicePluginAdapter implements CodingPluginAdapter {
  readonly pluginId = DATA_SERVICE_PLUGIN_ID;

  constructor(private readonly operations: DataServiceOperations) {}

  async inspect(projectPath: string): Promise<PluginBackendProjection> {
    try {
      return projection(await this.operations.inspect(projectPath));
    } catch {
      return {
        status: 'degraded',
        code: 'plugin_backend_unavailable',
        message: 'Data Service is temporarily unavailable',
        retryable: true,
      };
    }
  }

  async invoke(
    _context: TrustedCodingCapabilityContext,
    tool: CodingPluginToolDefinition,
    input: unknown,
  ): Promise<AdapterInvocationResult<DataServiceResult>> {
    if (!validateInput(tool, input)) {
      return failure('plugin_input_invalid', 'Data Service tool input is invalid');
    }
    try {
      return projectResult(await callDataService(
        this.operations,
        tool.name,
        input as InputRecord,
        _context.projectPath,
      ));
    } catch {
      return {
        success: false,
        status: 503,
        code: 'plugin_backend_unavailable',
        error: 'Data Service is temporarily unavailable',
        retryable: true,
        payload_schema: 'data-service.v1',
        data: null,
      };
    }
  }

  async deactivate(_projectPath: string): Promise<void> {
    // Data Service deactivation invalidates preview sessions in the dedicated
    // lifecycle owner; this adapter owns no independent process or token.
  }
}

export const createDataServicePluginAdapter = (
  operations: DataServiceOperations,
): DataServicePluginAdapter => new DataServicePluginAdapter(operations);