import { sessionStore } from '@electron/gateway/session-store';
import { getTranscriptFilePath } from '@electron/utils/token-usage-writer';
import { buildAgentSessionKey, normalizeAgentSessionKey, parseSessionKey } from '@runtime/lib/agents';
import type { HostApiContext } from '../context';
import type { NormalizedHostApiRequest } from '../route-utils';
import { fail, ok, parseJsonBody } from '../route-utils';

function parseSessionIdentity(request: NormalizedHostApiRequest): { agentId: string; sessionId: string; sessionKey: string } | null {
  const sessionKey = normalizeAgentSessionKey(request.url.searchParams.get('sessionKey')?.trim() || '');
  const parsed = parseSessionKey(sessionKey);
  if (sessionKey && parsed.isAgentSession) {
    return {
      agentId: parsed.agentId,
      sessionId: parsed.sessionId,
      sessionKey: parsed.sessionKey,
    };
  }

  const agentId = request.url.searchParams.get('agentId')?.trim() || '';
  const sessionId = request.url.searchParams.get('sessionId')?.trim() || '';
  if (!agentId || !sessionId) return null;

  return {
    agentId: parseSessionKey(buildAgentSessionKey(agentId, sessionId)).agentId,
    sessionId: parseSessionKey(buildAgentSessionKey(agentId, sessionId)).sessionId,
    sessionKey: buildAgentSessionKey(agentId, sessionId),
  };
}

export async function handleSessionRoutes(
  request: NormalizedHostApiRequest,
  _ctx: HostApiContext,
) {
  const { pathname, method } = request;

  if (pathname === '/api/sessions/transcript' && method === 'GET') {
    const identity = parseSessionIdentity(request);
    if (!identity) {
      return fail(400, 'sessionKey or agentId/sessionId is required');
    }

    try {
      const fsP = await import('node:fs/promises');
      const transcriptPath = getTranscriptFilePath(identity.sessionKey);
      let raw: string;

      try {
        raw = await fsP.readFile(transcriptPath, 'utf8');
      } catch (error: any) {
        const requestedSessionKey = request.url.searchParams.get('sessionKey')?.trim() || '';
        if (error?.code === 'ENOENT' && requestedSessionKey && requestedSessionKey !== identity.sessionKey) {
          raw = await fsP.readFile(getTranscriptFilePath(requestedSessionKey), 'utf8');
        } else {
          throw error;
        }
      }

      const lines = raw.split(/\r?\n/).filter(Boolean);
      const messages = lines.flatMap((line) => {
        try {
          const entry = JSON.parse(line) as { type?: string; message?: unknown; timestamp?: string };
          return entry.type === 'message' && entry.message ? [{ ...entry.message, timestamp: entry.timestamp }] : [];
        } catch {
          return [];
        }
      });

      return ok({
        agentId: identity.agentId,
        sessionId: identity.sessionId,
        sessionKey: identity.sessionKey,
        transcriptPath,
        messages,
      });
    } catch (error: any) {
      if (error?.code === 'ENOENT') {
        return fail(404, 'Transcript not found');
      }
      return fail(500, error instanceof Error ? error.message : String(error));
    }
  }

  if (pathname === '/api/sessions/delete' && method === 'POST') {
    const body = parseJsonBody<{ sessionKey: string }>(request.body);
    const rawSessionKey = String(body?.sessionKey || '').trim();
    const sessionKey = normalizeAgentSessionKey(rawSessionKey);
    if (!sessionKey) {
      return fail(400, 'sessionKey is required');
    }

    sessionStore.deleteSession(sessionKey);

    const transcriptPath = getTranscriptFilePath(sessionKey);
    try {
      const fsP = await import('node:fs/promises');
      await fsP.rename(transcriptPath, transcriptPath.replace(/\.jsonl$/, '.deleted.jsonl'));
    } catch {
      if (rawSessionKey && rawSessionKey !== sessionKey) {
        try {
          const fsP = await import('node:fs/promises');
          const legacyTranscriptPath = getTranscriptFilePath(rawSessionKey);
          await fsP.rename(legacyTranscriptPath, legacyTranscriptPath.replace(/\.jsonl$/, '.deleted.jsonl'));
        } catch {
          // Best effort: transcript may not exist yet.
        }
      }
    }

    return ok({ success: true });
  }

  return null;
}