import { NextResponse } from "next/server";
import { sql } from "@/db";
import { detectMedicalIntent, ESCALATION_RULES } from "@/lib/ai/medical-triggers";
import { logAudit } from "@/lib/audit";

const LITELLM_URL = process.env.LITELLM_BASE_URL;
const LITELLM_KEY = process.env.LITELLM_API_KEY;

export async function POST(request: Request) {
  try {
    // Check API key is configured
    if (!LITELLM_KEY) {
      return NextResponse.json({ error: "AI service not configured" }, { status: 503 });
    }

    const body = await request.json();
    const { messages, childId } = body;

    if (!messages || !Array.isArray(messages)) {
      return NextResponse.json({ error: "messages array required" }, { status: 400 });
    }

    const lastUserMsg = [...messages].reverse().find(m => m.role === "user")?.content || "";

    // HARD GUARDRAIL: Check for medical intent BEFORE calling LLM
    const intent = detectMedicalIntent(lastUserMsg);
    if (intent.isMedical) {
      // Fetch pediatrician phone
      const sessionToken = request.headers.get("cookie")?.match(/tia_session=([^;]+)/)?.[1] || "";
      const families = await sql`
        SELECT pediatrician_phone FROM families
        WHERE id IN (SELECT family_id FROM family_members WHERE user_id IN (SELECT user_id FROM sessions WHERE session_token = ${sessionToken}))
        LIMIT 1
      `;
      const pediatricianPhone = families[0]?.pediatrician_phone;

      const reply = [
        `I can't interpret symptoms — that's a pediatrician's job, not mine.`,
        ``,
        ESCALATION_RULES[intent.category],
        ``,
        pediatricianPhone
          ? `Call your pediatrician now: ${pediatricianPhone}`
          : `Add your pediatrician's phone in Settings so I can show it here.`,
      ].join("\n");

      // Audit log
      await logAudit({
        action: "ai_medical_redirect",
        metadata: { category: intent.category, keyword: intent.matchedKeyword },
        request,
      });

      return NextResponse.json({
        reply,
        redirected: true,
        category: intent.category,
      });
    }

    // Get child's context
    let context = "";
    if (childId) {
      const children = await sql.unsafe(
        `SELECT name, birth_date, sex FROM children WHERE id = $1`,
        [childId]
      );
      if (children.length > 0) {
        const child = children[0];
        const age = calculateAge(child.birth_date);
        context = `The child's name is ${child.name}, they are ${age} old. `;
      }
    }

    const systemMessage = {
      role: "system",
      content: `You are Tia, a friendly baby care assistant.

STRICT RULES:
- Never diagnose, interpret symptoms, or give medical advice
- Never recommend medications, dosages, or treatments
- If user describes symptoms, fever, rash, breathing issues — refuse and redirect to pediatrician
- Provide only general educational info (developmental milestones, food intro, sleep patterns)
- Always note "this is general info, not medical advice"
- Keep responses under 200 words
- Be warm but clinical`,
    };

    // Call LiteLLM
    const response = await fetch(`${LITELLM_URL}/v1/chat/completions`, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "Authorization": `Bearer ${LITELLM_KEY}`,
      },
      body: JSON.stringify({
        model: "minimax-2.7",
        messages: [systemMessage, ...messages],
        max_tokens: 500,
        temperature: 0.3,
      }),
    });

    if (!response.ok) {
      const error = await response.text();
      return NextResponse.json({ error: error }, { status: response.status });
    }

    const data = await response.json();
    return NextResponse.json({ reply: data.choices?.[0]?.message?.content });
  } catch (error) {
    console.error(error);
    return NextResponse.json({ error: String(error) }, { status: 500 });
  }
}

function calculateAge(birthDate: string) {
  const birth = new Date(birthDate);
  const now = new Date();
  const days = Math.floor((now.getTime() - birth.getTime()) / (1000 * 60 * 60 * 24));
  const months = Math.floor(days / 30);
  const years = Math.floor(months / 12);

  if (years > 0) return `${years} year${years > 1 ? "s" : ""} old`;
  if (months > 0) return `${months} month${months > 1 ? "s" : ""} old`;
  return `${days} day${days > 1 ? "s" : ""} old`;
}