import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient, PutCommand, QueryCommand } from '@aws-sdk/lib-dynamodb';
import { ulid } from 'ulid';

type Role = 'user' | 'assistant' | 'system';

const region = process.env.AWS_REGION!;
const tableName = process.env.CHAT_TABLE_NAME!;

const ddb = new DynamoDBClient({ region });
const doc = DynamoDBDocumentClient.from(ddb);

export type SessionItem = {
  pk: string; // SESSION#{sessionId}
  sk: 'SESSION';
  userId: string;
  companyId?: string | null;
  model?: string;
  promptId?: string;
  promptVersion?: string;
  createdAt: string;
  updatedAt: string;
};

export type MessageItem = {
  pk: string; // SESSION#{sessionId}
  sk: string; // MSG#{isoOrUlid}
  role: Role;
  content: string;
  createdAt: string;
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  redactions?: any;
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  toolCalls?: any;
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  evidenceJson?: any;
};

export async function createSession(params: { userId: string; companyId?: string | null; model?: string; promptId?: string; promptVersion?: string; }): Promise<string> {
  const sessionId = ulid();
  const now = new Date().toISOString();
  let item: SessionItem = {
    pk: `SESSION#${sessionId}`,
    sk: 'SESSION',
    userId: params.userId,
    createdAt: now,
    updatedAt: now,
  }
  if (params.companyId) {
    item.companyId = params.companyId;
  }
  if (params.model) {
    item.model = params.model;
  }
  if (params.promptId) {
    item.promptId = params.promptId;
  }
  if (params.promptVersion) {
    item.promptVersion = params.promptVersion;
  }
  await doc.send(new PutCommand({ TableName: tableName, Item: item }));
  return sessionId;
}

// eslint-disable-next-line @typescript-eslint/no-explicit-any
export async function putMessage(params: { sessionId: string; role: Role; content: string; evidenceJson?: any }): Promise<void> {
  const now = new Date().toISOString();
  const item: MessageItem = {
    pk: `SESSION#${params.sessionId}`,
    sk: `MSG#${ulid()}`,
    role: params.role,
    content: sanitizeContent(params.content),
    createdAt: now,
    evidenceJson: params.evidenceJson,
  } as MessageItem;
  await doc.send(new PutCommand({ TableName: tableName, Item: item }));
}

export async function getHistory(sessionId: string, limit: number = 20): Promise<Array<{ role: Role; content: string }>> {
  const resp = await doc.send(new QueryCommand({
    TableName: tableName,
    KeyConditionExpression: 'pk = :pk and begins_with(sk, :msg) ',
    ExpressionAttributeValues: { ':pk': `SESSION#${sessionId}`, ':msg': 'MSG#' },
    ScanIndexForward: true,
    Limit: limit,
  }));
  const items = (resp.Items || []) as MessageItem[];
  return items.map(it => ({ role: it.role, content: it.content })).slice(-limit);
}

function sanitizeContent(text: string): string {
  // Basic server-side redaction: do not persist raw secrets-looking strings
  try {
    return String(text).replace(/(api|secret|token|password)[=:]\s*[^\s"']+/gi, '$1=[REDACTED]');
  } catch {
    return text;
  }
}