import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { generateText, stepCountIs } from "ai";
import { db, chatMessages, aiConversations, sql } from "@epicure/db";
import { requireSessionOrApiKey } from "@/lib/api-auth";
import { applyRateLimit } from "@/lib/rate-limit";
import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
import { getModelConfigForUseCase } from "@/lib/ai/resolve-user-key";
import { resolveModel } from "@/lib/ai/factory";
import { getUserPrivateBio, buildUserBioContext } from "@/lib/ai/user-bio";
import { createRecipeTool } from "@/lib/ai/tools/create-recipe-tool";
import { addToShoppingListTool } from "@/lib/ai/tools/add-to-shopping-list-tool";

const Schema = z.object({
  question: z.string().min(1).max(500),
  conversationId: z.string().uuid().optional(),
});

const LANG: Record<string, string> = { en: "English", fr: "French" };

export async function POST(req: NextRequest) {
  const { session, response } = await requireSessionOrApiKey(req);
  if (response) return response;

  const body = await req.json() as unknown;
  const parsed = Schema.safeParse(body);
  if (!parsed.success) {
    return NextResponse.json({ error: "Validation error" }, { status: 400 });
  }

  const limited = await applyRateLimit(`rl:ai:${session!.user.id}`, 30, 60);
  if (limited) return limited;

  const [configResult, privateBio] = await Promise.all([
    resolveAiConfigOrError(() => getModelConfigForUseCase(session!.user.id, "text")),
    getUserPrivateBio(session!.user.id),
  ]);
  if (!configResult.ok) return configResult.response;
  const aiConfig = configResult.data;
  const model = resolveModel(aiConfig);
  const bioContext = buildUserBioContext(privateBio);
  const locale = (session!.user as { locale?: string }).locale ?? "en";
  const lang = LANG[locale] ?? "English";

  const result = await withAiQuota(session!.user.id, session!.user.tier as "free" | "pro" | "team", () =>
    generateText({
      model,
      system: `You are Epicure, a helpful culinary assistant answering general cooking questions — not tied to any specific recipe (techniques, substitutions, timing, equipment, food safety, etc). If asked who you are or what model/AI you're built on, say you're Epicure — never name the underlying model or provider. If a question has nothing to do with cooking or food, politely redirect. Keep answers under 200 words. Respond in ${lang}.\n\nYou have two tools, both of which only draft something for the user to review — neither saves anything by itself, so still write a short text reply too when you use one (e.g. "Here's a draft — check it below and confirm if it looks right").\n- createRecipe: only when the user explicitly asks you to create, save, or write down a recipe (e.g. "make me a recipe for X", "write that down as a recipe"). Don't call it just because a recipe came up in conversation.\n- addToShoppingList: only when the user explicitly asks to add ingredients/items to a shopping list (e.g. "add that to my shopping list").${bioContext}`,
      prompt: parsed.data.question,
      tools: { createRecipe: createRecipeTool, addToShoppingList: addToShoppingListTool },
      stopWhen: stepCountIs(3),
    }), { skipQuota: aiConfig.isByok }
  );
  if (!result.ok) return result.response;

  const { conversationId } = parsed.data;
  const proposedRecipe = result.data.toolCalls.find((c) => c.toolName === "createRecipe")?.input;
  const proposedShoppingList = result.data.toolCalls.find((c) => c.toolName === "addToShoppingList")?.input;

  void db.insert(chatMessages).values([
    { id: crypto.randomUUID(), userId: session!.user.id, recipeId: null, conversationId, role: "user", content: parsed.data.question },
    { id: crypto.randomUUID(), userId: session!.user.id, recipeId: null, conversationId, role: "assistant", content: result.data.text },
  ]).catch((err) => console.error("[cooking-chat] failed to persist chat history", err));

  if (conversationId) {
    // Bumps updatedAt (for the conversation list's sort order) and, only if
    // this is the conversation's first message, auto-titles it from the
    // opening question — so users aren't left staring at "Untitled" entries;
    // they can still rename it later.
    void db.execute(sql`
      UPDATE ${aiConversations}
      SET updated_at = now(), title = COALESCE(title, ${parsed.data.question.slice(0, 60)})
      WHERE ${aiConversations.id} = ${conversationId} AND ${aiConversations.userId} = ${session!.user.id}
    `).catch((err) => console.error("[cooking-chat] failed to touch conversation", err));
  }

  return NextResponse.json({ answer: result.data.text, proposedRecipe, proposedShoppingList });
}