import type { ProviderAccount } from '@runtime/lib/providers';
import {
  DEFAULT_AGENT_ID,
  DEFAULT_MAIN_SESSION_SUFFIX,
  buildMainSessionKey,
  normalizeAgentId,
  type AgentSummary,
} from '@runtime/lib/agents';
import type { HostApiContext } from '../context';
import type { NormalizedHostApiRequest } from '../route-utils';
import { ok } from '../route-utils';

function formatModelDisplay(modelRef: string | null | undefined, fallbackLabel: string): string {
  const trimmed = String(modelRef ?? '').trim();
  if (!trimmed) return fallbackLabel;

  const parts = trimmed.split('/');
  return parts[parts.length - 1] || trimmed;
}

function buildMainAgent(defaultAccount: ProviderAccount | null): AgentSummary {
  return {
    id: DEFAULT_AGENT_ID,
    name: 'Main Agent',
    isDefault: true,
    providerAccountId: defaultAccount?.id ?? null,
    modelRef: defaultAccount?.model ?? null,
    modelDisplay: formatModelDisplay(defaultAccount?.model, defaultAccount?.label || 'Unassigned'),
    mainSessionKey: buildMainSessionKey(DEFAULT_AGENT_ID, DEFAULT_MAIN_SESSION_SUFFIX),
    vendorId: defaultAccount?.vendorId ?? null,
    source: 'synthetic-main',
  };
}

function buildProviderBackedAgents(accounts: ProviderAccount[]): AgentSummary[] {
  const seen = new Set<string>();
  const summaries: AgentSummary[] = [];

  for (const account of accounts) {
    const agentId = normalizeAgentId(account.id);
    if (seen.has(agentId) || agentId === DEFAULT_AGENT_ID) continue;
    seen.add(agentId);

    summaries.push({
      id: agentId,
      name: account.label || agentId,
      isDefault: false,
      providerAccountId: account.id,
      modelRef: account.model ?? null,
      modelDisplay: formatModelDisplay(account.model, account.label || agentId),
      mainSessionKey: buildMainSessionKey(agentId, DEFAULT_MAIN_SESSION_SUFFIX),
      vendorId: account.vendorId,
      source: 'provider-account',
    });
  }

  return summaries;
}

export async function handleAgentRoutes(
  request: NormalizedHostApiRequest,
  ctx: HostApiContext,
) {
  const { pathname, method } = request;
  if (pathname !== '/api/agents' || method !== 'GET') {
    return null;
  }

  const accounts = ctx.providerApiService
    .getAccounts()
    .filter((account) => account.enabled !== false);
  const defaultAccountId = ctx.providerApiService.getDefault().accountId;
  const defaultAccount = accounts.find((account) => account.id === defaultAccountId) ?? accounts[0] ?? null;

  const agents = [
    buildMainAgent(defaultAccount),
    ...buildProviderBackedAgents(accounts),
  ];

  return ok({
    success: true,
    agents,
    defaultAgentId: DEFAULT_AGENT_ID,
    defaultProviderAccountId: defaultAccount?.id ?? null,
    defaultModelRef: defaultAccount?.model ?? null,
    mainSessionSuffix: DEFAULT_MAIN_SESSION_SUFFIX,
    configuredChannelTypes: [],
    channelOwners: {},
    channelAccountOwners: {},
  });
}