import type { FastifyInstance } from "fastify";
import type { PiProcessManager } from "../pi/pi-process-manager.js";
import type { ThtRunner } from "../tht/tht-runner.js";
import type { SseHub } from "../sse/sse-hub.js";
import type { Settings } from "../settings/settings-store.js";
import { getUser } from "../auth/auth.js";
import type { ReadinessManager } from "../runtime/readiness-manager.js";

export function sessionRoutes(
  app: FastifyInstance,
  d: { mgr: PiProcessManager; tht: ThtRunner; hub: SseHub; getSettings: () => Settings; readiness: ReadinessManager },
) {
  const info = (id: string, text: string, level = "info") =>
    d.hub.publish(id, "info", { type: "info", level, text });

  const bindRuntime = (id: string, rt: ReturnType<PiProcessManager["createFor"]>) =>
    rt.bridge.onClientEvent((e) => {
      if (e.type === "system_event" && e.event === "session_failed") {
        void d.tht.failSession(id, d.getSettings().workspace).catch(() => undefined);
      }
      d.hub.publish(id, e.type, e);
    });

  const bootstrap = (
    id: string,
    rt: ReturnType<PiProcessManager["createFor"]>,
    configure: Promise<void>,
    retrieval: Promise<void> | null,
    start: () => void,
  ) => {
    void (async () => {
      try {
        if (retrieval) info(id, "Preparing retrieval context");
        await Promise.all([configure, retrieval]);
        info(id, "Starting model");
        start();
      } catch (error) {
        d.mgr.teardown(id);
        const text = error instanceof Error ? error.message : String(error);
        void d.tht.failSession(id, d.getSettings().workspace).catch(() => undefined);
        rt.bridge.emitClientEvent({ type: "info", level: "error", text: `Session bootstrap failed: ${text}` });
        rt.bridge.emitClientEvent({ type: "system_event", event: "session_failed" });
        rt.bridge.emitClientEvent({ type: "system_event", event: "agent_end" });
      }
    })();
  };

  app.post("/runtime/prewarm", async (_req, reply) => {
    const workspace = d.getSettings().workspace ?? "";
    void d.readiness.ensure(workspace).catch(() => undefined);
    return reply.code(202).send({ status: "warming" });
  });

  app.post("/sessions", async (req, reply) => {
    const b = req.body as { question: string; name?: string };
    const s = d.getSettings();
    const ensure = await d.readiness.ensure(s.workspace ?? "");
    if (!ensure.ok) return reply.code(503).send({ error: ensure.error ?? "Ollama/embeddings non disponibili" });
    // Settings (global) supply workspace/provider/model/thinking. The new-question
    // form sends only the question text. `workspace` selects the tht `-c <config>`.
    const { id } = await d.tht.sessionNew({
      question: b.question,
      name: b.name,
      workspace: s.workspace,
      provider: s.provider,
      model: s.model,
      thinking: s.thinking,
    });
    const options = {
      provider: s.provider,
      model: s.model,
      thinking: s.thinking,
      author: getUser(req).id,
      question: b.question,
    };
    const rt = d.mgr.createFor(id, options);
    bindRuntime(id, rt);
    info(id, "Session created");
    bootstrap(
      id, rt, d.mgr.configure(rt, options),
      d.tht.searchPack(b.question, id, s.workspace),
      () => d.mgr.start(id, rt, options),
    );
    return { id };
  });
  app.get("/sessions", async () => d.tht.sessionList(d.getSettings().workspace));
  app.get("/sessions/:id", async (req) => d.tht.sessionShow((req.params as any).id, d.getSettings().workspace));
  app.post("/sessions/:id/response", async (req, reply) => {
    const id = (req.params as any).id;
    const rt = d.mgr.get(id);
    if (!rt) return reply.code(404).send({ error: "sessione non attiva" });
    rt.bridge.respond((req.body as any).ui_response);
    return reply.code(204).send();
  });
  app.post("/sessions/:id/steer", async (req, reply) => {
    const rt = d.mgr.get((req.params as any).id);
    if (!rt) return reply.code(404).send({ error: "sessione non attiva" });
    rt.bridge.steer((req.body as any).text);
    return reply.code(204).send();
  });
  app.post("/sessions/:id/resume", async (req, reply) => {
    const id = (req.params as any).id;
    const existing = d.mgr.get(id);
    if (existing) {
      const state = existing.bridge.turnState();
      if (state === "running" || state === "waiting") {
        return reply.code(200).send({ id, alreadyActive: true });
      }
      d.mgr.teardown(id);
      d.hub.clear(id);
    }
    const manifest = (await d.tht.sessionShow(id, d.getSettings().workspace)) as { status?: string; archived?: boolean } | null;
    if (manifest?.status === "finalized" || manifest?.archived) {
      return reply.code(409).send({ error: "sessione in sola lettura (finalizzata o archiviata)" });
    }
    const settings = d.getSettings();
    const ensure = await d.readiness.ensure(settings.workspace ?? "");
    if (!ensure.ok) return reply.code(503).send({ error: ensure.error ?? "Ollama/embeddings non disponibili" });
    const saved = manifest as { provider?: string; model?: string; thinking?: string } | null;
    const options = {
      provider: saved?.provider,
      model: saved?.model,
      thinking: saved?.thinking ?? settings.thinking,
      author: getUser(req).id,
      mode: "resume" as const,
    };
    await d.tht.reopenSession(id, settings.workspace);
    const rt = d.mgr.createFor(id, options);
    bindRuntime(id, rt);
    info(id, "Resuming session");
    bootstrap(id, rt, d.mgr.configure(rt, options), null, () => d.mgr.start(id, rt, options));
    return reply.code(200).send({ id });
  });
  app.post("/sessions/:id/close", async (req) => {
    const id = (req.params as { id: string }).id;
    try {
      await d.tht.closeSession(id, d.getSettings().workspace);
    } finally {
      d.mgr.teardown(id);
      d.hub.clear(id);
    }
    return { closed: true };
  });
  app.get("/sessions/:id/events", (req, reply) => {
    const id = (req.params as any).id;
    const rt = d.mgr.get(id);
    // Add CORS headers manually: reply.raw.writeHead bypasses Fastify's onSend hooks
    // (where @fastify/cors injects headers), so we must set them explicitly here.
    const origin = (req.headers.origin as string | undefined) ?? "*";
    reply.raw.writeHead(200, {
      "Content-Type": "text/event-stream",
      "Cache-Control": "no-cache",
      "X-Accel-Buffering": "no",
      Connection: "keep-alive",
      "Access-Control-Allow-Origin": origin,
      "Access-Control-Allow-Credentials": "true",
    });
    // Send the handshake immediately. Without this, Node waits for the first event body and
    // proxies/clients cannot establish an idle SSE subscription or inspect its headers.
    reply.raw.flushHeaders();
    const send = (event: string, data: object) => reply.raw.write(`event: ${event}\ndata: ${JSON.stringify(data)}\n\n`);
    const off = d.hub.subscribe(id, send, rt?.bridge.pendingWidget() ?? null);
    req.raw.on("close", off);
  });
  app.post("/sessions/:id/rename", async (req, reply) => {
    await d.tht.setName((req.params as any).id, (req.body as any).name);
    return reply.code(204).send();
  });
  app.post("/sessions/:id/group", async (req, reply) => {
    await d.tht.setGroup((req.params as any).id, (req.body as any).group);
    return reply.code(204).send();
  });
  app.post("/sessions/:id/archive", async (req, reply) => {
    await d.tht.archive((req.params as any).id);
    return reply.code(204).send();
  });
  app.post("/sessions/:id/unarchive", async (req, reply) => {
    await d.tht.unarchive((req.params as any).id);
    return reply.code(204).send();
  });
  app.delete("/sessions/:id", async (req, reply) => {
    const id = (req.params as any).id;
    d.mgr.teardown(id); // drop any live runtime before deleting on disk
    await d.tht.deleteSession(id, d.getSettings().workspace);
    return reply.code(204).send();
  });
  app.get("/sessions/:id/documents", async (req) => d.tht.documents((req.params as any).id));
}