import { performance } from "node:perf_hooks";
import { prisma } from "../db.js";
import { anthropicClient, openaiClient, xaiClient } from "./providers.js";
import {
  buildToolLogMessageData,
  runToolAwareChatCompletionsStream,
  runToolAwareOpenAIChatStream,
  type ToolExecutionEvent,
} from "./chat-tools.js";
import { buildAnthropicConversationMessage, getAnthropicSystemPrompt } from "./message-content.js";
import type { MultiplexRequest, Provider } from "./types.js";

type StreamUsage = {
  inputTokens?: number;
  outputTokens?: number;
  totalTokens?: number;
};

export type StreamEvent =
  | { type: "meta"; chatId: string | null; callId: string | null; provider: Provider; model: string }
  | { type: "tool_call"; event: ToolExecutionEvent }
  | { type: "delta"; text: string }
  | { type: "done"; text: string; usage?: StreamUsage }
  | { type: "error"; message: string };

function getChatIdOrCreate(chatId?: string) {
  if (chatId) return Promise.resolve(chatId);
  return prisma.chat.create({ data: {}, select: { id: true } }).then((c) => c.id);
}

export async function* runMultiplexStream(req: MultiplexRequest): AsyncGenerator<StreamEvent> {
  const t0 = performance.now();
  const shouldPersist = req.persist !== false;
  const chatId = shouldPersist ? await getChatIdOrCreate(req.chatId) : null;

  const call =
    shouldPersist && chatId
      ? await prisma.llmCall.create({
          data: {
            chatId,
            provider: req.provider as any,
            model: req.model,
            request: req as any,
          },
          select: { id: true },
        })
      : null;

  if (shouldPersist && chatId) {
    await prisma.$transaction([
      prisma.chat.update({
        where: { id: chatId },
        data: {
          lastUsedProvider: req.provider as any,
          lastUsedModel: req.model,
        },
      }),
      prisma.chat.updateMany({
        where: { id: chatId, initiatedProvider: null },
        data: {
          initiatedProvider: req.provider as any,
          initiatedModel: req.model,
        },
      }),
    ]);
  }

  yield { type: "meta", chatId, callId: call?.id ?? null, provider: req.provider, model: req.model };

  let text = "";
  let usage: StreamUsage | undefined;
  let raw: unknown = { streamed: true };

  try {
    if (req.provider === "openai" || req.provider === "xai") {
      const client = req.provider === "openai" ? openaiClient() : xaiClient();
      const streamEvents =
        req.provider === "openai"
          ? runToolAwareOpenAIChatStream({
              client,
              model: req.model,
              messages: req.messages,
              temperature: req.temperature,
              maxTokens: req.maxTokens,
              logContext: {
                provider: req.provider,
                model: req.model,
                chatId: chatId ?? undefined,
              },
            })
          : runToolAwareChatCompletionsStream({
              client,
              model: req.model,
              messages: req.messages,
              temperature: req.temperature,
              maxTokens: req.maxTokens,
              logContext: {
                provider: req.provider,
                model: req.model,
                chatId: chatId ?? undefined,
              },
            });
      for await (const ev of streamEvents) {
        if (ev.type === "delta") {
          text += ev.text;
          yield { type: "delta", text: ev.text };
          continue;
        }

        if (ev.type === "tool_call") {
          if (shouldPersist && chatId) {
            const toolMessage = buildToolLogMessageData(chatId, ev.event);
            await prisma.message.create({
              data: {
                chatId: toolMessage.chatId,
                role: toolMessage.role as any,
                content: toolMessage.content,
                name: toolMessage.name,
                metadata: toolMessage.metadata as any,
              },
            });
          }
          yield { type: "tool_call", event: ev.event };
          continue;
        }

        raw = ev.result.raw;
        usage = ev.result.usage;
        text = ev.result.text;
      }
    } else if (req.provider === "anthropic") {
      const client = anthropicClient();

      const system = getAnthropicSystemPrompt(req.messages);
      const msgs = req.messages.filter((message) => message.role !== "system").map((message) => buildAnthropicConversationMessage(message));

      const stream = await client.messages.create({
        model: req.model,
        system,
        max_tokens: req.maxTokens ?? 1024,
        temperature: req.temperature,
        messages: msgs as any,
        stream: true,
      });

      for await (const ev of stream as any as AsyncIterable<any>) {
        // Anthropic streaming events include content_block_delta with text_delta
        if (ev?.type === "content_block_delta" && ev?.delta?.type === "text_delta") {
          const delta = ev.delta.text ?? "";
          if (delta) {
            text += delta;
            yield { type: "delta", text: delta };
          }
        }
        // capture usage if present on message_delta
        if (ev?.type === "message_delta" && ev?.usage) {
          usage = {
            inputTokens: ev.usage.input_tokens,
            outputTokens: ev.usage.output_tokens,
            totalTokens:
              (ev.usage.input_tokens ?? 0) + (ev.usage.output_tokens ?? 0),
          };
        }
        // some streams end with message_stop
      }
      raw = { streamed: true, provider: "anthropic" };
    } else {
      throw new Error(`unknown provider: ${req.provider}`);
    }

    const latencyMs = Math.round(performance.now() - t0);

    if (shouldPersist && chatId && call) {
      await prisma.$transaction(async (tx) => {
        await tx.message.create({
          data: { chatId, role: "assistant" as any, content: text },
        });
        await tx.llmCall.update({
          where: { id: call.id },
          data: {
            response: raw as any,
            latencyMs,
            inputTokens: usage?.inputTokens,
            outputTokens: usage?.outputTokens,
            totalTokens: usage?.totalTokens,
          },
        });
      });
    }

    yield { type: "done", text, usage };
  } catch (e: any) {
    const latencyMs = Math.round(performance.now() - t0);
    if (shouldPersist && call) {
      await prisma.llmCall.update({
        where: { id: call.id },
        data: {
          error: e?.message ?? String(e),
          latencyMs,
        },
      });
    }
    yield { type: "error", message: e?.message ?? String(e) };
  }
}