clicktrack/app/api/tracks/route.ts

import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { getTempoMapsForSong, getSongByMbid, insertTempoMap, upsertSong } from "@/lib/db/client";
import { validateCTP } from "@/lib/ctp/validate";
import { lookupRecording, formatArtistCredit, mbDurationToSeconds } from "@/lib/musicbrainz/client";

// ─── GET /api/tracks?mbid=<uuid> ─────────────────────────────────────────────

const GetSchema = z.object({
  mbid: z.string().uuid(),
});

export async function GET(req: NextRequest) {
  const params = Object.fromEntries(req.nextUrl.searchParams);
  const parsed = GetSchema.safeParse(params);

  if (!parsed.success) {
    return NextResponse.json(
      { error: "mbid (UUID) is required" },
      { status: 400 }
    );
  }

  const maps = await getTempoMapsForSong(parsed.data.mbid);
  return NextResponse.json({ maps });
}

// ─── POST /api/tracks ─────────────────────────────────────────────────────────
// Body: a raw CTP document JSON

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 validation = validateCTP(body);
  if (!validation.success) {
    return NextResponse.json(
      {
        error: "CTP document validation failed",
        details: validation.errors.flatten(),
      },
      { status: 422 }
    );
  }

  const doc = validation.data;

  if (!doc.metadata.mbid) {
    return NextResponse.json(
      { error: "CTP document must include a metadata.mbid to be stored" },
      { status: 422 }
    );
  }

  // Ensure the song exists — auto-register it if not
  const existing = await getSongByMbid(doc.metadata.mbid);

  if (!existing) {
    try {
      const rec = await lookupRecording(doc.metadata.mbid);
      await upsertSong({
        mbid: doc.metadata.mbid,
        title: rec.title,
        artist: formatArtistCredit(rec["artist-credit"]),
        duration_seconds: mbDurationToSeconds(rec.length),
        acousticbrainz_bpm: null,
        acousticbrainz_time_sig_num: null,
        source: "musicbrainz",
      });
    } catch {
      // MusicBrainz unreachable — fall back to CTP metadata
      await upsertSong({
        mbid: doc.metadata.mbid,
        title: doc.metadata.title,
        artist: doc.metadata.artist,
        duration_seconds: doc.metadata.duration_seconds,
        acousticbrainz_bpm: null,
        acousticbrainz_time_sig_num: null,
        source: "manual",
      });
    }
  }

  const map = await insertTempoMap({
    song_mbid: doc.metadata.mbid,
    ctp_data: body as Record<string, unknown>,
    contributed_by: doc.metadata.contributed_by,
  });

  return NextResponse.json({ map }, { status: 201 });
}