import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { generateCTPWithAI } from "@/lib/analysis/ai-ctp";
import { validateCTP } from "@/lib/ctp/validate";

// ─── Request schema ───────────────────────────────────────────────────────────

const AnalyzeRequestSchema = z.object({
  bpm: z.number().min(20).max(400),
  duration: z.number().positive(),
  title: z.string().min(1).max(256).optional(),
  artist: z.string().min(1).max(256).optional(),
  mbid: z.string().uuid().optional().nullable(),
  contributed_by: z.string().min(1).max(64).optional(),
});

/**
 * POST /api/analyze
 *
 * Accepts BPM detection results from the browser and uses Claude to generate
 * a draft CTP document for human review.
 *
 * Body (JSON):
 *   { bpm, duration, title?, artist?, mbid?, contributed_by? }
 *
 * Returns:
 *   { ctp: CTPDocument, warnings: string[] }
 */
export async function POST(req: NextRequest) {
  let body: unknown;
  try {
    body = await req.json();
  } catch {
    return NextResponse.json({ error: "Invalid JSON body" }, { status: 400 });
  }

  const parsed = AnalyzeRequestSchema.safeParse(body);
  if (!parsed.success) {
    return NextResponse.json(
      { error: "Invalid request", details: parsed.error.flatten() },
      { status: 400 }
    );
  }

  const { bpm, duration, title, artist, mbid, contributed_by } = parsed.data;

  if (!process.env.ANTHROPIC_API_KEY) {
    return NextResponse.json(
      { error: "ANTHROPIC_API_KEY is not configured on this server" },
      { status: 503 }
    );
  }

  let ctpDoc;
  try {
    ctpDoc = await generateCTPWithAI({
      bpm,
      duration,
      title,
      artist,
      mbid: mbid ?? null,
      contributedBy: contributed_by ?? "anonymous",
    });
  } catch (err) {
    console.error("[analyze] AI generation failed:", err);
    return NextResponse.json(
      { error: "Failed to generate CTP document", detail: String(err) },
      { status: 500 }
    );
  }

  // Validate the AI output against the CTP schema
  const validation = validateCTP(ctpDoc);
  const warnings: string[] = [];

  if (!validation.success) {
    // Rather than 500-ing, return the draft with validation warnings so the user
    // can still see and manually correct it.
    warnings.push(...validation.errors.issues.map((i) => `${i.path.join(".")}: ${i.message}`));
  }

  return NextResponse.json({ ctp: ctpDoc, warnings });
}