'use client';

import { useState } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { apiFetch } from '../../../lib/api';
import { useSession } from '../../../components/session-provider';

interface Deal {
  id: string; title: string; stage: string;
  organizationId: string | null; contactId: string | null;
  valueMinorUnits: number | null; currency: string | null;
  probability: number | null; expectedCloseDate: string | null;
  notes: string | null; createdAt: string;
}
interface Organization { id: string; name: string; }

const STAGES = [
  { key: 'identified',  label: 'Identificat',  color: 'bg-sky-400' },
  { key: 'qualified',   label: 'Calificat',     color: 'bg-primary' },
  { key: 'proposal',    label: 'Propunere',     color: 'bg-amber-400' },
  { key: 'negotiation', label: 'Negociere',     color: 'bg-orange-500' },
  { key: 'won',         label: 'Câștigat',      color: 'bg-signal-ok' },
  { key: 'lost',        label: 'Pierdut',       color: 'bg-signal-danger' },
];

function fmtMoney(minor: number | null, currency: string | null) {
  if (!minor) return '—';
  return new Intl.NumberFormat('ro-RO', { style: 'currency', currency: currency ?? 'RON', minimumFractionDigits: 0 }).format(minor / 100);
}

export default function PipelinePage() {
  const { activeTenant } = useSession();
  const tenantId = activeTenant?.tenantId ?? '';
  const qc = useQueryClient();
  const [showCreate, setShowCreate] = useState(false);
  const [form, setForm] = useState({ title: '', stage: 'identified', probability: '50', expectedCloseDate: '' });

  const { data: deals = [], isLoading } = useQuery({
    queryKey: ['pipeline', tenantId],
    queryFn: () => apiFetch<Deal[]>('/v1/pipeline', { tenantId }),
    enabled: Boolean(tenantId),
    staleTime: 60_000,
  });
  const { data: orgs = [] } = useQuery({
    queryKey: ['orgs', tenantId],
    queryFn: () => apiFetch<Organization[]>('/v1/organizations', { tenantId }),
    enabled: Boolean(tenantId), staleTime: 300_000,
  });
  const orgMap = Object.fromEntries(orgs.map((o) => [o.id, o.name]));

  const { mutate: create, isPending } = useMutation({
    mutationFn: () => apiFetch<Deal>('/v1/pipeline', {
      method: 'POST',
      body: { ...form, probability: parseInt(form.probability) || 50 },
      tenantId,
    }),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ['pipeline', tenantId] });
      setShowCreate(false);
      setForm({ title: '', stage: 'identified', probability: '50', expectedCloseDate: '' });
    },
  });

  const { mutate: advanceStage } = useMutation({
    mutationFn: ({ id, stage }: { id: string; stage: string }) =>
      apiFetch(`/v1/pipeline/${id}`, { method: 'PATCH', body: { stage }, tenantId }),
    onSuccess: () => qc.invalidateQueries({ queryKey: ['pipeline', tenantId] }),
  });

  const active = deals.filter((d) => !['won', 'lost'].includes(d.stage));
  const closed = deals.filter((d) => ['won', 'lost'].includes(d.stage));
  const pipelineValue = active.reduce((s, d) => s + (d.valueMinorUnits ?? 0) * ((d.probability ?? 50) / 100), 0);
  const primaryCurrency = deals.find((d) => d.currency)?.currency ?? 'RON';

  // Group by stage
  const byStage: Record<string, Deal[]> = {};
  for (const s of STAGES) byStage[s.key] = [];
  for (const d of deals) {
    if (!byStage[d.stage]) byStage[d.stage] = [];
    byStage[d.stage].push(d);
  }

  const stageIdx = Object.fromEntries(STAGES.map((s, i) => [s.key, i]));
  const nextStage = (stage: string) => STAGES[stageIdx[stage] + 1]?.key;

  return (
    <div className="max-w-6xl space-y-6 p-6">
      <div className="flex items-center justify-between gap-4 flex-wrap">
        <div>
          <h1 className="font-display text-2xl font-semibold text-ink">Pipeline Vânzări</h1>
          <p className="text-sm text-ink-faint mt-1">
            {active.length} deal-uri active · Valoare ponderată: {fmtMoney(Math.round(pipelineValue), primaryCurrency)}
          </p>
        </div>
        <button onClick={() => setShowCreate(true)} className="btn btn-primary text-xs px-4 py-2">+ Deal nou</button>
      </div>

      {showCreate && (
        <div className="card p-5 space-y-4 border-primary/30">
          <h2 className="text-sm font-semibold text-ink">Deal nou</h2>
          <div className="grid grid-cols-1 gap-3 sm:grid-cols-2">
            <div className="sm:col-span-2">
              <label className="text-xs text-ink-faint block mb-1">Titlu deal *</label>
              <input value={form.title} onChange={(e) => setForm((f) => ({ ...f, title: e.target.value }))}
                placeholder="Contract SaaS — Firma XYZ"
                className="w-full rounded-lg border bg-card px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-ring" />
            </div>
            <div>
              <label className="text-xs text-ink-faint block mb-1">Etapă</label>
              <select value={form.stage} onChange={(e) => setForm((f) => ({ ...f, stage: e.target.value }))}
                className="w-full rounded-lg border bg-card px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-ring">
                {STAGES.filter((s) => !['won','lost'].includes(s.key)).map((s) => <option key={s.key} value={s.key}>{s.label}</option>)}
              </select>
            </div>
            <div>
              <label className="text-xs text-ink-faint block mb-1">Probabilitate ({form.probability}%)</label>
              <input type="range" min="0" max="100" step="5" value={form.probability}
                onChange={(e) => setForm((f) => ({ ...f, probability: e.target.value }))}
                className="w-full" />
            </div>
            <div>
              <label className="text-xs text-ink-faint block mb-1">Data estimată close</label>
              <input type="date" value={form.expectedCloseDate}
                onChange={(e) => setForm((f) => ({ ...f, expectedCloseDate: e.target.value }))}
                className="w-full rounded-lg border bg-card px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-ring" />
            </div>
          </div>
          <div className="flex gap-3">
            <button onClick={() => create()} disabled={isPending || !form.title.trim()}
              className="btn btn-primary text-xs px-4 py-2 disabled:opacity-50">
              {isPending ? 'Se salvează…' : 'Salvează'}
            </button>
            <button onClick={() => setShowCreate(false)} className="text-xs text-ink-faint hover:text-ink">Anulează</button>
          </div>
        </div>
      )}

      {isLoading ? <div className="card p-8 text-center text-sm text-ink-faint">Se încarcă…</div>
        : deals.length === 0 ? (
          <div className="card p-12 text-center space-y-2">
            <p className="text-3xl">🎯</p>
            <p className="text-sm text-ink-faint">Niciun deal în pipeline.</p>
            <button onClick={() => setShowCreate(true)} className="text-xs text-bronze-deep hover:underline">Adaugă primul deal →</button>
          </div>
        ) : (
          <>
            {/* Stage columns */}
            <div className="grid grid-cols-2 gap-3 lg:grid-cols-4">
              {STAGES.filter((s) => !['won','lost'].includes(s.key)).map((stage) => {
                const stageDeals = byStage[stage.key] ?? [];
                return (
                  <div key={stage.key} className="card p-3 space-y-2">
                    <div className="flex items-center gap-2">
                      <div className={`w-2 h-2 rounded-full ${stage.color}`} />
                      <p className="text-xs font-semibold text-ink">{stage.label}</p>
                      <span className="ml-auto text-[10px] text-ink-faint">{stageDeals.length}</span>
                    </div>
                    {stageDeals.length === 0 && <p className="text-[10px] text-ink-faint text-center py-2">Gol</p>}
                    {stageDeals.map((d) => {
                      const next = nextStage(d.stage);
                      return (
                        <div key={d.id} className="rounded-lg border bg-card/50 p-2.5 space-y-1.5">
                          <p className="text-xs font-medium text-ink line-clamp-2">{d.title}</p>
                          {d.organizationId && orgMap[d.organizationId] && (
                            <p className="text-[10px] text-ink-faint">@ {orgMap[d.organizationId]}</p>
                          )}
                          <div className="flex items-center justify-between">
                            <span className="text-[10px] text-ink-faint">{d.probability ?? 50}%</span>
                            {fmtMoney(d.valueMinorUnits, d.currency) !== '—' && (
                              <span className="text-[10px] font-medium text-ink">{fmtMoney(d.valueMinorUnits, d.currency)}</span>
                            )}
                          </div>
                          {next && (
                            <button onClick={() => advanceStage({ id: d.id, stage: next })}
                              className="w-full text-[10px] text-bronze-deep border border-bronze-deep/20 rounded py-0.5 hover:bg-bronze-deep/5">
                              → {STAGES.find((s) => s.key === next)?.label}
                            </button>
                          )}
                        </div>
                      );
                    })}
                  </div>
                );
              })}
            </div>

            {/* Won/Lost summary */}
            {closed.length > 0 && (
              <div className="grid grid-cols-2 gap-3">
                {[['won','Câștigate'],['lost','Pierdute']].map(([stage, label]) => {
                  const stageDeals = byStage[stage] ?? [];
                  return (
                    <div key={stage} className="card p-4 space-y-2">
                      <p className="text-xs font-semibold text-ink">{label} ({stageDeals.length})</p>
                      {stageDeals.slice(0, 3).map((d) => (
                        <p key={d.id} className="text-xs text-ink-faint line-clamp-1">
                          {d.title} — {fmtMoney(d.valueMinorUnits, d.currency)}
                        </p>
                      ))}
                    </div>
                  );
                })}
              </div>
            )}
          </>
        )
      }
    </div>
  );
}