"use client";

import { useState } from "react";
import { Loader2, ChevronLeft, Check } from "lucide-react";
import { toast } from "sonner";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import {
  useReconciliationLedger, useStyleDistance, usePairDetail, usePromoteLearning,
  type DraftFinalPair,
} from "@/lib/api/learning";

/**
 * /training "למידה" tab (T6/T13) — the reconciliation ledger (INV-LRN4): every
 * decision and its draft↔final comparison status, plus per-case style-distance
 * (T7). The list is the chair's "have we closed each decision against Dafna's
 * final?" surface.
 */

const STATUS_LABEL: Record<string, string> = {
  final_received: "התקבל סופי — ממתין לניתוח",
  analyzed: "נותח (הצעות ממתינות)",
  lessons_folded: "לקחים הוטמעו",
};
const STATUS_CLASS: Record<string, string> = {
  final_received: "bg-gold-wash text-gold-deep border-gold/40",
  analyzed: "bg-navy-soft/20 text-navy",
  lessons_folded: "bg-emerald-50 text-emerald-800 border-emerald-300/60",
};

function fmtDate(iso: string | null) {
  if (!iso) return "—";
  try { return new Date(iso).toLocaleDateString("he-IL"); } catch { return iso; }
}

function StyleDistanceDetail({ caseNumber }: { caseNumber: string }) {
  const { data, isPending, error } = useStyleDistance(caseNumber);
  if (isPending) return <Loader2 className="w-4 h-4 animate-spin text-ink-muted" />;
  if (error || data?.error) return <p className="text-danger text-[0.75rem]">{data?.error || "שגיאה"}</p>;
  if (!data) return null;
  const s = data.summary;
  return (
    <div className="rounded-md bg-rule-soft/30 border border-rule p-3 space-y-2 text-[0.8rem]">
      <div className="flex gap-4 flex-wrap">
        <span>שינוי draft→final: <b className="tabular-nums">{s.change_percent ?? "—"}%</b></span>
        <span>סטיית יחסי-זהב מקס׳: <b className="tabular-nums">{s.ratio_max_deviation_pp ?? "—"} נק׳</b></span>
        <span>אנטי-דפוסים: <b className="tabular-nums">{s.anti_pattern_total}</b></span>
      </div>
      {Object.keys(data.golden_ratio_adherence.sections).length > 0 && (
        <div className="flex gap-3 flex-wrap text-[0.72rem] text-ink-muted">
          {Object.entries(data.golden_ratio_adherence.sections).map(([sec, v]) => (
            <span key={sec} className={v.deviation_pp > 0 ? "text-danger" : ""}>
              {sec}: {v.actual_pct}% (יעד {v.target[0]}-{v.target[1]})
            </span>
          ))}
        </div>
      )}
      {data.anti_pattern_hits.total > 0 && (
        <div className="text-[0.72rem] text-danger">
          {Object.entries(data.anti_pattern_hits.by_pattern).map(([n, v]) => (
            <span key={n} className="me-3">{n}: {v.count}</span>
          ))}
        </div>
      )}
    </div>
  );
}

function SelectableItem({ text, selected, onToggle }: {
  text: string; selected: boolean; onToggle: () => void;
}) {
  return (
    <button type="button" onClick={onToggle}
      className={`w-full flex items-start gap-2 rounded-md border p-2 text-right text-[0.78rem] transition-colors ${
        selected ? "border-navy bg-navy-soft/15" : "border-rule bg-surface hover:bg-rule-soft/30"
      }`}>
      <span className={`mt-0.5 w-4 h-4 shrink-0 rounded border flex items-center justify-center ${
        selected ? "bg-navy border-navy text-parchment" : "border-rule"
      }`}>
        {selected && <Check className="w-3 h-3" />}
      </span>
      <span className="flex-1">{text}</span>
    </button>
  );
}

/** T14 — chair approval gate (INV-G10/LRN1): review the curator's style_method
 * proposal and fold approved lessons/phrases into writer-consumed channels. */
function ProposalReview({ pairId }: { pairId: string }) {
  const { data, isPending, error } = usePairDetail(pairId);
  const promote = usePromoteLearning(pairId);
  const [lessons, setLessons] = useState<Set<string>>(new Set());
  const [phrases, setPhrases] = useState<Set<string>>(new Set());

  if (isPending) return <Loader2 className="w-4 h-4 animate-spin text-ink-muted" />;
  if (error || !data) return <p className="text-danger text-[0.75rem]">שגיאה בטעינת ההצעה.</p>;

  const lessonTexts = data.changes.map((c) => c.lesson).filter((l): l is string => Boolean(l));
  const toggle = (set: Set<string>, setFn: (s: Set<string>) => void, v: string) => {
    const next = new Set(set);
    next.has(v) ? next.delete(v) : next.add(v);
    setFn(next);
  };
  const total = lessons.size + phrases.size;

  return (
    <div className="rounded-md bg-gold-wash/30 border border-gold/40 p-3 space-y-3 text-[0.8rem]">
      <p className="text-ink-muted text-[0.75rem]">
        הצעת הדיסטילציה (סגנון/שיטה בלבד — INV-LRN5). בחר/י מה לאמץ; ייכתב לערוצים שהכותב צורך (שער-יו&quot;ר).
      </p>
      {data.overall_assessment && (
        <p className="italic text-ink-muted">{data.overall_assessment}</p>
      )}
      {lessonTexts.length > 0 && (
        <div className="space-y-1.5">
          <div className="font-semibold text-navy text-[0.75rem]">לקחי-סגנון → כללי-דיון</div>
          {lessonTexts.map((l, i) => (
            <SelectableItem key={`l${i}`} text={l} selected={lessons.has(l)}
              onToggle={() => toggle(lessons, setLessons, l)} />
          ))}
        </div>
      )}
      {data.new_expressions.length > 0 && (
        <div className="space-y-1.5">
          <div className="font-semibold text-navy text-[0.75rem]">ביטויי-מעבר חדשים</div>
          {data.new_expressions.map((p, i) => (
            <SelectableItem key={`p${i}`} text={p} selected={phrases.has(p)}
              onToggle={() => toggle(phrases, setPhrases, p)} />
          ))}
        </div>
      )}
      {lessonTexts.length === 0 && data.new_expressions.length === 0 && (
        <p className="text-ink-muted">אין הצעות style_method.</p>
      )}
      <div className="flex justify-end">
        <Button size="sm" disabled={total === 0 || promote.isPending}
          className="bg-navy text-parchment hover:bg-navy-soft"
          onClick={() => promote.mutate(
            { lessons: [...lessons], phrases: [...phrases] },
            {
              onSuccess: (r) => toast.success(`הוטמעו ${r.folded_lessons} לקחים + ${r.folded_phrases} ביטויים`),
              onError: (e) => toast.error(e instanceof Error ? e.message : "שגיאה"),
            },
          )}>
          {promote.isPending ? <Loader2 className="w-3.5 h-3.5 animate-spin me-1" />
            : <Check className="w-3.5 h-3.5 me-1" />}
          אשר והטמע {total > 0 ? `(${total})` : ""}
        </Button>
      </div>
    </div>
  );
}

function Row({ pair }: { pair: DraftFinalPair }) {
  const [open, setOpen] = useState(false);
  return (
    <div className="rounded-lg border border-rule bg-surface overflow-hidden">
      <button type="button" onClick={() => setOpen((o) => !o)}
        className="w-full flex items-center gap-3 px-4 py-3 text-right hover:bg-gold-wash/30 transition-colors">
        <ChevronLeft className={`w-4 h-4 text-ink-muted shrink-0 transition-transform ${open ? "-rotate-90" : ""}`} />
        <div className="flex-1 min-w-0 text-right">
          <div className="font-semibold text-navy truncate">{pair.case_number || "—"}{pair.title ? ` — ${pair.title}` : ""}</div>
          <div className="text-[0.72rem] text-ink-muted">עודכן {fmtDate(pair.updated_at)}</div>
        </div>
        {pair.change_percent != null && (
          <Badge variant="outline" className="tabular-nums text-[0.65rem]">Δ {pair.change_percent}%</Badge>
        )}
        <Badge variant="outline" className={`text-[0.65rem] ${STATUS_CLASS[pair.status] ?? ""}`}>
          {STATUS_LABEL[pair.status] ?? pair.status}
        </Badge>
      </button>
      {open && (
        <div className="px-4 pb-3 space-y-3">
          {pair.status === "analyzed" && <ProposalReview pairId={pair.id} />}
          {pair.case_number && <StyleDistanceDetail caseNumber={pair.case_number} />}
        </div>
      )}
    </div>
  );
}

export function LearningPanel() {
  const { data, isPending, error } = useReconciliationLedger();
  if (error) return <p className="text-danger text-sm">שגיאה בטעינת הפנקס.</p>;
  if (isPending) return <Loader2 className="w-5 h-5 animate-spin text-ink-muted" />;

  const items = data?.items ?? [];
  return (
    <div className="space-y-3">
      <p className="text-[0.8rem] text-ink-muted">
        פנקס-ההתאמה (INV-LRN4): כל החלטה נסגרת מול הסופי של דפנה; כל סופי מנותח מול הטיוטה.
        לחיצה על תיק → מדד מרחק-הסגנון שלו.
      </p>
      {items.length === 0 ? (
        <p className="text-ink-muted text-sm py-8 text-center">אין עדיין השוואות. הן נוצרות כשמסמנים החלטה כסופית.</p>
      ) : (
        items.map((p) => <Row key={p.id} pair={p} />)
      )}
    </div>
  );
}