/* ── EUMORA API client ────────────────────────────────────────────────────── */

import { EMOTIONS, BACKEND_EMOTION_MAP, type EmotionPreset } from "./data";

const API_URL =
  process.env.NEXT_PUBLIC_API_URL?.replace(/\/$/, "") || "http://localhost:8000";

// ── Types ────────────────────────────────────────────────────────────────────

export interface BackendTrack {
  name:          string;
  artist:        string;
  album:         string;
  album_art?:    string;
  spotify_url?:  string;
  preview_url?:  string | null;
  popularity:    number;
  match_score:   number;
}

export interface BackendResult {
  emotion:              string;
  confidence:           number;
  probabilities:        Record<string, number>;
  explanation?:         string;
  music_context?:       Record<string, unknown>;
  targets_used?:        Record<string, unknown> | null;
  tracks:               BackendTrack[];
  spotify_unavailable?: boolean;
}

/** The shape consumed by the New Frontend UI */
export interface AnalysisResult {
  emotion:    string;          // key in EMOTIONS (melancholy, euphoric, etc.)
  confidence: number;          // 0–1
  summary:    string;          // poetic descriptor
  tracks:     DisplayTrack[];  // either from Spotify or curated fallback
  fromBackend: boolean;        // true if real backend was used
}

export interface DisplayTrack {
  title:      string;
  artist:     string;
  album:      string;
  year:       number | string;
  duration:   string;
  album_art?: string;
  spotify_url?: string;
  match_score?: number;
}

// ── API call ─────────────────────────────────────────────────────────────────

/**
 * Call the backend /api/recommend endpoint and translate the response into
 * the format expected by the New Frontend UI.
 *
 * Falls back to curated presets if:
 *  - Backend is unreachable
 *  - Spotify is unavailable on the backend
 */
export async function analyze(text: string): Promise<AnalysisResult> {
  try {
    const res = await fetch(`${API_URL}/api/recommend`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ text, limit: 10 }),
    });

    if (!res.ok) {
      throw new Error(`Backend returned ${res.status}`);
    }

    const data: BackendResult = await res.json();

    // Map backend emotion → frontend emotion key
    const frontendEmotion = BACKEND_EMOTION_MAP[data.emotion] ?? "melancholy";
    const emo: EmotionPreset = EMOTIONS[frontendEmotion] ?? EMOTIONS.melancholy;

    // If Spotify returned real tracks, use them
    if (data.tracks && data.tracks.length > 0 && !data.spotify_unavailable) {
      const displayTracks: DisplayTrack[] = data.tracks.map((t) => ({
        title:       t.name,
        artist:      t.artist,
        album:       t.album,
        year:        "",
        duration:    "",
        album_art:   t.album_art,
        spotify_url: t.spotify_url,
        match_score: t.match_score,
      }));

      return {
        emotion:    frontendEmotion,
        confidence: data.confidence,
        summary:    data.explanation || emo.descriptor,
        tracks:     displayTracks,
        fromBackend: true,
      };
    }

    // Spotify unavailable — use curated fallback tracks
    return {
      emotion:    frontendEmotion,
      confidence: data.confidence,
      summary:    data.explanation || emo.descriptor,
      tracks:     emo.tracks.map((t) => ({ ...t, year: t.year })),
      fromBackend: true,
    };
  } catch {
    // Backend completely unreachable — do client-side fallback
    return analyzeClientFallback(text);
  }
}

// ── Client-side fallback ─────────────────────────────────────────────────────

function analyzeClientFallback(text: string): AnalysisResult {
  const t = text.toLowerCase();
  const score: Record<string, number> = {};
  const kw: Record<string, string[]> = {
    melancholy: ["sad", "heavy", "blue", "rain", "alone", "empty", "tired", "ache"],
    euphoric:   ["smiling", "alive", "happy", "joy", "ecstatic", "high", "best", "summer", "sun"],
    anxious:    ["panic", "spiral", "anxious", "racing", "can't", "3am", "awake", "stress"],
    lonely:     ["lonely", "miss", "without", "her name", "his name", "empty room", "alone"],
    nostalgic:  ["remember", "back when", "used to", "old", "childhood", "summer of", "missed"],
    yearning:   ["want", "need you", "long for", "wish", "ache", "almost", "across"],
    peaceful:   ["calm", "quiet", "still", "soft", "warm", "easy", "settled"],
    defiant:    ["hate", "no more", "done", "fight", "scream", "burn", "angry"],
  };

  Object.entries(kw).forEach(([emo, words]) => {
    score[emo] = words.reduce((s, w) => s + (t.includes(w) ? 1 : 0), 0);
  });

  const sorted = Object.entries(score).sort((a, b) => b[1] - a[1]);
  const top = sorted[0][1] > 0 ? sorted[0][0] : "melancholy";
  const confidence = sorted[0][1] > 0
    ? Math.min(0.95, 0.6 + sorted[0][1] * 0.08)
    : 0.52;

  const emo = EMOTIONS[top] ?? EMOTIONS.melancholy;

  return {
    emotion:    top,
    confidence,
    summary:    emo.descriptor,
    tracks:     emo.tracks.map((tr) => ({ ...tr, year: tr.year })),
    fromBackend: false,
  };
}