import { performance } from "node:perf_hooks";
import { z } from "zod";
import type { FastifyInstance } from "fastify";
import { prisma } from "./db.js";
import { requireAdmin } from "./auth.js";
import { env } from "./env.js";
import { runMultiplex } from "./llm/multiplexer.js";
import { runMultiplexStream } from "./llm/streaming.js";
import { exaClient } from "./search/exa.js";

type IncomingChatMessage = {
  role: "system" | "user" | "assistant" | "tool";
  content: string;
  name?: string;
};

function sameMessage(a: IncomingChatMessage, b: IncomingChatMessage) {
  return a.role === b.role && a.content === b.content && (a.name ?? null) === (b.name ?? null);
}

async function storeNonAssistantMessages(chatId: string, messages: IncomingChatMessage[]) {
  const incoming = messages.filter((m) => m.role !== "assistant");
  if (!incoming.length) return;

  const existing = await prisma.message.findMany({
    where: { chatId },
    orderBy: { createdAt: "asc" },
    select: { role: true, content: true, name: true },
  });
  const existingNonAssistant = existing.filter((m) => m.role !== "assistant");

  let sharedPrefix = 0;
  const max = Math.min(existingNonAssistant.length, incoming.length);
  while (sharedPrefix < max && sameMessage(existingNonAssistant[sharedPrefix] as IncomingChatMessage, incoming[sharedPrefix])) {
    sharedPrefix += 1;
  }

  if (sharedPrefix === incoming.length) return;
  const toInsert = sharedPrefix === existingNonAssistant.length ? incoming.slice(existingNonAssistant.length) : incoming;
  if (!toInsert.length) return;

  await prisma.message.createMany({
    data: toInsert.map((m) => ({
      chatId,
      role: m.role as any,
      content: m.content,
      name: m.name,
    })),
  });
}

export async function registerRoutes(app: FastifyInstance) {
  app.get("/health", async () => ({ ok: true }));

  app.get("/v1/auth/session", async (req) => {
    requireAdmin(req);
    return { authenticated: true, mode: env.ADMIN_TOKEN ? "token" : "open" };
  });

  app.get("/v1/chats", async (req) => {
    requireAdmin(req);
    const chats = await prisma.chat.findMany({
      orderBy: { updatedAt: "desc" },
      take: 100,
      select: { id: true, title: true, createdAt: true, updatedAt: true },
    });
    return { chats };
  });

  app.post("/v1/chats", async (req) => {
    requireAdmin(req);
    const Body = z.object({ title: z.string().optional() });
    const body = Body.parse(req.body ?? {});
    const chat = await prisma.chat.create({ data: { title: body.title } });
    return { chat };
  });

  app.get("/v1/searches", async (req) => {
    requireAdmin(req);
    const searches = await prisma.search.findMany({
      orderBy: { updatedAt: "desc" },
      take: 100,
      select: { id: true, title: true, query: true, createdAt: true, updatedAt: true },
    });
    return { searches };
  });

  app.post("/v1/searches", async (req) => {
    requireAdmin(req);
    const Body = z.object({ title: z.string().optional(), query: z.string().optional() });
    const body = Body.parse(req.body ?? {});
    const title = body.title?.trim() || body.query?.trim()?.slice(0, 80);
    const query = body.query?.trim() || null;
    const search = await prisma.search.create({
      data: {
        title: title || null,
        query,
      },
      select: { id: true, title: true, query: true, createdAt: true, updatedAt: true },
    });
    return { search };
  });

  app.get("/v1/searches/:searchId", async (req) => {
    requireAdmin(req);
    const Params = z.object({ searchId: z.string() });
    const { searchId } = Params.parse(req.params);

    const search = await prisma.search.findUnique({
      where: { id: searchId },
      include: { results: { orderBy: { rank: "asc" } } },
    });
    if (!search) return app.httpErrors.notFound("search not found");
    return { search };
  });

  app.post("/v1/searches/:searchId/run", async (req) => {
    requireAdmin(req);
    const Params = z.object({ searchId: z.string() });
    const Body = z.object({
      query: z.string().trim().min(1).optional(),
      title: z.string().trim().min(1).optional(),
      type: z.enum(["auto", "fast", "deep", "instant"]).optional(),
      numResults: z.number().int().min(1).max(25).optional(),
      includeDomains: z.array(z.string().trim().min(1)).max(50).optional(),
      excludeDomains: z.array(z.string().trim().min(1)).max(50).optional(),
    });

    const { searchId } = Params.parse(req.params);
    const body = Body.parse(req.body ?? {});

    const existing = await prisma.search.findUnique({
      where: { id: searchId },
      select: { id: true, query: true },
    });
    if (!existing) return app.httpErrors.notFound("search not found");

    const query = body.query?.trim() || existing.query?.trim();
    if (!query) return app.httpErrors.badRequest("query is required");

    const startedAt = performance.now();

    try {
      const exa = exaClient();
      const [searchOutcome, answerOutcome] = await Promise.allSettled([
        exa.searchAndContents(query, {
          type: body.type ?? "auto",
          numResults: body.numResults ?? 10,
          includeDomains: body.includeDomains,
          excludeDomains: body.excludeDomains,
          text: { maxCharacters: 1200 },
          highlights: {
            query,
            maxCharacters: 320,
            numSentences: 2,
            highlightsPerUrl: 2,
          },
          moderation: true,
          userLocation: "US",
        } as any),
        exa.answer(query, {
          text: true,
          model: "exa",
          userLocation: "US",
        }),
      ]);

      const searchResponse = searchOutcome.status === "fulfilled" ? searchOutcome.value : null;
      const answerResponse = answerOutcome.status === "fulfilled" ? answerOutcome.value : null;
      const searchError = searchOutcome.status === "rejected" ? searchOutcome.reason?.message ?? String(searchOutcome.reason) : null;
      const answerError = answerOutcome.status === "rejected" ? answerOutcome.reason?.message ?? String(answerOutcome.reason) : null;

      const latencyMs = Math.round(performance.now() - startedAt);
      const normalizedTitle = body.title?.trim() || query.slice(0, 80);
      const rows = (searchResponse?.results ?? []).map((result: any, index: number) => ({
        searchId,
        rank: index,
        title: result.title ?? null,
        url: result.url,
        publishedDate: result.publishedDate ?? null,
        author: result.author ?? null,
        text: result.text ?? null,
        highlights: Array.isArray(result.highlights) ? (result.highlights as any) : null,
        highlightScores: Array.isArray(result.highlightScores) ? (result.highlightScores as any) : null,
        score: typeof result.score === "number" ? result.score : null,
        favicon: result.favicon ?? null,
        image: result.image ?? null,
      }));
      const answerText =
        typeof answerResponse?.answer === "string"
          ? answerResponse.answer
          : answerResponse?.answer
            ? JSON.stringify(answerResponse.answer, null, 2)
            : null;

      await prisma.$transaction(async (tx) => {
        await tx.search.update({
          where: { id: searchId },
          data: {
            query,
            title: normalizedTitle,
            requestId: searchResponse?.requestId ?? null,
            rawResponse: searchResponse as any,
            latencyMs,
            error: searchError,
            answerText,
            answerRequestId: answerResponse?.requestId ?? null,
            answerCitations: (answerResponse?.citations as any) ?? null,
            answerRawResponse: answerResponse as any,
            answerError,
          },
        });
        await tx.searchResult.deleteMany({ where: { searchId } });
        if (rows.length) {
          await tx.searchResult.createMany({ data: rows as any });
        }
      });

      if (searchError && answerError) {
        throw app.httpErrors.badGateway(`Exa search and answer failed: ${searchError}; ${answerError}`);
      }

      const search = await prisma.search.findUnique({
        where: { id: searchId },
        include: { results: { orderBy: { rank: "asc" } } },
      });
      if (!search) return app.httpErrors.notFound("search not found");
      return { search };
    } catch (err: any) {
      await prisma.search.update({
        where: { id: searchId },
        data: {
          latencyMs: Math.round(performance.now() - startedAt),
          error: err?.message ?? String(err),
        },
      });
      throw err;
    }
  });

  app.get("/v1/chats/:chatId", async (req) => {
    requireAdmin(req);
    const Params = z.object({ chatId: z.string() });
    const { chatId } = Params.parse(req.params);

    const chat = await prisma.chat.findUnique({
      where: { id: chatId },
      include: { messages: { orderBy: { createdAt: "asc" } }, calls: { orderBy: { createdAt: "desc" } } },
    });
    if (!chat) return app.httpErrors.notFound("chat not found");
    return { chat };
  });

  app.post("/v1/chats/:chatId/messages", async (req) => {
    requireAdmin(req);
    const Params = z.object({ chatId: z.string() });
    const Body = z.object({
      role: z.enum(["system", "user", "assistant", "tool"]),
      content: z.string(),
      name: z.string().optional(),
      metadata: z.unknown().optional(),
    });

    const { chatId } = Params.parse(req.params);
    const body = Body.parse(req.body);

    const msg = await prisma.message.create({
      data: {
        chatId,
        role: body.role as any,
        content: body.content,
        name: body.name,
        metadata: body.metadata as any,
      },
    });

    return { message: msg };
  });

  // Main: create a completion via provider+model and store everything.
  app.post("/v1/chat-completions", async (req) => {
    requireAdmin(req);

    const Body = z.object({
      chatId: z.string().optional(),
      provider: z.enum(["openai", "anthropic", "xai"]),
      model: z.string().min(1),
      messages: z.array(
        z.object({
          role: z.enum(["system", "user", "assistant", "tool"]),
          content: z.string(),
          name: z.string().optional(),
        })
      ),
      temperature: z.number().min(0).max(2).optional(),
      maxTokens: z.number().int().positive().optional(),
    });

    const body = Body.parse(req.body);

    // ensure chat exists if provided
    if (body.chatId) {
      const exists = await prisma.chat.findUnique({ where: { id: body.chatId }, select: { id: true } });
      if (!exists) return app.httpErrors.notFound("chat not found");
    }

    // Store only new non-assistant messages to avoid duplicate history entries.
    if (body.chatId) {
      await storeNonAssistantMessages(body.chatId, body.messages);
    }

    const result = await runMultiplex(body);

    return {
      chatId: body.chatId ?? null,
      ...result,
    };
  });

  // Streaming SSE endpoint.
  app.post("/v1/chat-completions/stream", async (req, reply) => {
    requireAdmin(req);

    const Body = z.object({
      chatId: z.string().optional(),
      provider: z.enum(["openai", "anthropic", "xai"]),
      model: z.string().min(1),
      messages: z.array(
        z.object({
          role: z.enum(["system", "user", "assistant", "tool"]),
          content: z.string(),
          name: z.string().optional(),
        })
      ),
      temperature: z.number().min(0).max(2).optional(),
      maxTokens: z.number().int().positive().optional(),
    });

    const body = Body.parse(req.body);

    // ensure chat exists if provided
    if (body.chatId) {
      const exists = await prisma.chat.findUnique({ where: { id: body.chatId }, select: { id: true } });
      if (!exists) return app.httpErrors.notFound("chat not found");
    }

    // Store only new non-assistant messages to avoid duplicate history entries.
    if (body.chatId) {
      await storeNonAssistantMessages(body.chatId, body.messages);
    }

    reply.raw.writeHead(200, {
      "Content-Type": "text/event-stream; charset=utf-8",
      "Cache-Control": "no-cache, no-transform",
      Connection: "keep-alive",
    });

    const send = (event: string, data: any) => {
      reply.raw.write(`event: ${event}\n`);
      reply.raw.write(`data: ${JSON.stringify(data)}\n\n`);
    };

    for await (const ev of runMultiplexStream(body)) {
      if (ev.type === "meta") send("meta", ev);
      else if (ev.type === "delta") send("delta", ev);
      else if (ev.type === "done") send("done", ev);
      else if (ev.type === "error") send("error", ev);
    }

    reply.raw.end();
    return reply;
  });
}