/**
 * Turns whatever JSON the local model returns into {summary, insight}.
 *
 * The models routinely invent their own field names — `tren_mortalitas_harian`,
 * `dampak_populasi`, `rekomendasi_tindakan` instead of `kesimpulan`/`insight`.
 * The old per-page parser answered that by substituting a cheerful default
 * ("Analisis operasional kandang terpantau dengan baik."), which could mask a
 * report of total flock loss, and the counting page answered it by discarding
 * the response outright.
 *
 * Rule here: never invent reassuring text, and never silently drop content. Any
 * field the model produced is folded into the output; only a response with no
 * usable text at all returns null, so the UI can show a real error instead.
 */

export interface AiResult {
  summary: string;
  insight: string;
}

/** Field names seen standing in for the conclusion. */
const KESIMPULAN_KEYS = [
  'kesimpulan',
  'kesimpulan_analisis',
  'ringkasan',
  'headline',
  'summary',
  'conclusion',
];

/** Field names seen standing in for the recommendation. */
const INSIGHT_KEYS = [
  'insight',
  'insights',
  'rekomendasi',
  'rekomendasi_tindakan',
  'tindakan',
  'saran',
  'actions',
  'recommendations',
];

const isPlainObject = (value: unknown): value is Record<string, unknown> =>
  typeof value === 'object' && value !== null && !Array.isArray(value);

/** Turns a leftover field name into a readable label: `tren_mortalitas_harian` -> `Tren mortalitas harian`. */
const humanizeKey = (key: string) => {
  const spaced = key.replace(/[_-]+/g, ' ').replace(/([a-z])([A-Z])/g, '$1 $2');
  return spaced.charAt(0).toUpperCase() + spaced.slice(1);
};

/** Flattens any value into readable plain text. Arrays become bullet lines. */
const renderValue = (value: unknown, depth = 0): string => {
  if (value === null || value === undefined) return '';
  if (typeof value === 'string') return value.trim();
  if (typeof value === 'number' || typeof value === 'boolean') return String(value);

  if (Array.isArray(value)) {
    return value
      .map((item) => renderValue(item, depth + 1))
      .filter((item) => item.length > 0)
      .map((item) => (depth === 0 ? `• ${item}` : item))
      .join('\n');
  }

  if (isPlainObject(value)) {
    return Object.entries(value)
      .map(([key, nested]) => {
        const rendered = renderValue(nested, depth + 1);
        return rendered ? `${humanizeKey(key)}: ${rendered}` : '';
      })
      .filter((line) => line.length > 0)
      .join('\n');
  }

  return '';
};

const takeFirst = (source: Record<string, unknown>, keys: string[]) => {
  for (const key of keys) {
    if (key in source) {
      const rendered = renderValue(source[key]);
      if (rendered) return { key, text: rendered };
    }
  }
  return null;
};

/** Strips think-tags, code fences, comments and trailing commas, then isolates the JSON object. */
const extractJsonObject = (text: string): string | null => {
  const cleaned = text
    .replace(/<think>[\s\S]*?<\/think>/gi, '')
    .replace(/^```(?:json)?\s*/i, '')
    .replace(/\s*```\s*$/, '')
    .replace(/\/\/.*/g, '')
    .replace(/\/\*[\s\S]*?\*\//g, '')
    .replace(/,\s*([}\]])/g, '$1')
    .trim();

  const first = cleaned.indexOf('{');
  const last = cleaned.lastIndexOf('}');
  if (first === -1 || last === -1 || last <= first) return null;
  return cleaned.slice(first, last + 1);
};

export const parseAiResult = (text: string): AiResult | null => {
  if (!text || typeof text !== 'string') return null;

  const candidate = extractJsonObject(text);
  if (!candidate) return null;

  let parsed: unknown;
  try {
    parsed = JSON.parse(candidate);
  } catch {
    return null;
  }
  if (!isPlainObject(parsed)) return null;

  const used = new Set<string>();

  const kesimpulanHit = takeFirst(parsed, KESIMPULAN_KEYS);
  if (kesimpulanHit) used.add(kesimpulanHit.key);

  const insightHit = takeFirst(parsed, INSIGHT_KEYS);
  if (insightHit) used.add(insightHit.key);

  // Anything the model invented a name for still carries its analysis, so it is
  // appended under a readable label rather than thrown away.
  const leftovers = Object.entries(parsed)
    .filter(([key]) => !used.has(key))
    .map(([key, value]) => {
      const rendered = renderValue(value);
      return rendered ? `${humanizeKey(key)}: ${rendered}` : '';
    })
    .filter((line) => line.length > 0);

  let kesimpulan = kesimpulanHit?.text ?? '';
  let insight = insightHit?.text ?? '';

  if (!kesimpulan && leftovers.length > 0) {
    // Promote the first salvaged field to the conclusion so the card is never
    // headed by a generic sentence the model never wrote.
    kesimpulan = leftovers.shift() as string;
  }
  if (leftovers.length > 0) {
    insight = [insight, ...leftovers].filter(Boolean).join('\n\n');
  }

  if (!kesimpulan && !insight) return null;

  return {
    summary: kesimpulan || 'Model tidak mengembalikan ringkasan eksplisit.',
    insight: insight || 'Model tidak mengembalikan rekomendasi eksplisit.',
  };
};