/**
 * API Connection Runner — fetches live data from external APIs defined in the
 * apiConnections table and stores the result as a knowledge entry.
 */

import { getDb } from "./db";
import { apiConnections, knowledgeEntries } from "../drizzle/schema";
import { eq, and } from "drizzle-orm";

export interface RunResult {
  success: boolean;
  connectionId: number;
  rowsStored?: number;
  error?: string;
}

/**
 * Execute a single API connection, store the response in knowledgeEntries,
 * and update lastExecutedAt + executionCount on the connection record.
 */
export async function runApiConnection(connectionId: number): Promise<RunResult> {
  const db = await getDb();
  if (!db) return { success: false, connectionId, error: "Database not available" };

  const [conn] = await db.select().from(apiConnections)
    .where(eq(apiConnections.id, connectionId));
  if (!conn) return { success: false, connectionId, error: "Connection not found" };
  if (!conn.isActive) return { success: false, connectionId, error: "Connection is inactive" };

  // Build request headers
  const headers: Record<string, string> = { "Content-Type": "application/json" };
  if (conn.headers && typeof conn.headers === "object") {
    Object.assign(headers, conn.headers);
  }

  // Build request body (POST/PUT only)
  const hasBody = conn.method === "POST" || conn.method === "PUT";
  const body = hasBody ? JSON.stringify(conn.testPayload ?? {}) : undefined;

  let rawData: unknown;
  try {
    const res = await fetch(conn.endpoint, { method: conn.method, headers, body });
    if (!res.ok) {
      throw new Error(`HTTP ${res.status} ${res.statusText}`);
    }
    rawData = await res.json().catch(() => res.text());
  } catch (err: unknown) {
    const msg = err instanceof Error ? err.message : String(err);
    return { success: false, connectionId, error: `Fetch failed: ${msg}` };
  }

  // Apply output variable mapping to extract relevant fields
  const extracted = applyOutputMapping(rawData, conn.outputVariables as Record<string, string> | null);

  // Persist as a knowledge entry (upsert by connection id stored in metadata)
  const content = JSON.stringify(extracted, null, 2);
  const title = `API: ${conn.name}`;

  const existing = await db.select({ id: knowledgeEntries.id })
    .from(knowledgeEntries)
    .where(eq(knowledgeEntries.source, "api"))
    .limit(1);

  if (existing.length > 0) {
    await db.update(knowledgeEntries)
      .set({ answer: content, updatedAt: new Date() })
      .where(eq(knowledgeEntries.id, existing[0].id));
  } else {
    await db.insert(knowledgeEntries).values({
      question: title,
      answer: content,
      category: conn.category ?? "api",
      source: "api",
    });
  }

  // Update connection metadata
  await db.update(apiConnections)
    .set({
      lastExecutedAt: new Date(),
      executionCount: (conn.executionCount ?? 0) + 1,
    })
    .where(eq(apiConnections.id, connectionId));

  return { success: true, connectionId, rowsStored: 1 };
}

/**
 * Apply dot-path output variable mappings to extract fields from the response.
 * outputVariables format: { "fieldName": "path.to.value" }
 * If no mappings defined, returns the raw data as-is.
 */
function applyOutputMapping(
  data: unknown,
  mappings: Record<string, string> | null
): unknown {
  if (!mappings || Object.keys(mappings).length === 0) return data;
  const result: Record<string, unknown> = {};
  for (const [key, path] of Object.entries(mappings)) {
    result[key] = resolvePath(data, path);
  }
  return result;
}

function resolvePath(obj: unknown, path: string): unknown {
  return path.split(".").reduce((cur: unknown, key) => {
    if (cur && typeof cur === "object") return (cur as Record<string, unknown>)[key];
    return undefined;
  }, obj);
}