frontend/strategy.html

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  <title>Strategy P/L — Options Pricer</title>
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</head>
<body class="antialiased">
  <div class="wrapper" x-data="strategyApp()" x-init="init()">

    <!-- Sidebar -->
    <aside class="navbar navbar-vertical navbar-expand-lg" data-bs-theme="dark">
      <div class="container-fluid">
        <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#sb-menu" aria-label="Toggle navigation"><span class="navbar-toggler-icon"></span></button>
        <h1 class="navbar-brand navbar-brand-autodark">
          <a href="index.html" class="text-decoration-none d-flex align-items-center gap-2">
            <svg xmlns="http://www.w3.org/2000/svg" width="28" height="28" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path stroke="none" d="M0 0h24v24H0z" fill="none"/><rect x="4" y="8" width="4" height="8" rx="1"/><line x1="6" y1="4" x2="6" y2="8"/><line x1="6" y1="16" x2="6" y2="20"/><rect x="16" y="6" width="4" height="10" rx="1"/><line x1="18" y1="2" x2="18" y2="6"/><line x1="18" y1="16" x2="18" y2="22"/></svg>
            <span class="fw-bold">Options Pricer</span>
          </a>
        </h1>
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          <ul class="navbar-nav pt-lg-3">
            <li class="nav-item"><a class="nav-link" href="index.html"><span class="nav-link-icon d-md-none d-lg-inline-block"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"/><path d="M5 12l-2 0l9 -9l9 9l-2 0"/><path d="M5 12v7a2 2 0 0 0 2 2h10a2 2 0 0 0 2 -2v-7"/><path d="M9 21v-6a2 2 0 0 1 2 -2h2a2 2 0 0 1 2 2v6"/></svg></span><span class="nav-link-title">Dashboard</span></a></li>
            <li class="nav-item"><a class="nav-link" href="chain.html"><span class="nav-link-icon d-md-none d-lg-inline-block"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"/><rect x="3" y="5" width="18" height="14" rx="2"/><path d="M3 10l18 0"/><path d="M10 5v14"/></svg></span><span class="nav-link-title">Options Chain</span></a></li>
            <li class="nav-item"><a class="nav-link" href="surface.html"><span class="nav-link-icon d-md-none d-lg-inline-block"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"/><path d="M3 12c1.333 -4.667 2.667 -7 4 -7s2.667 2.333 4 7s2.667 7 4 7s2.667 -2.333 4 -7"/></svg></span><span class="nav-link-title">Vol Surface</span></a></li>
            <li class="nav-item active"><a class="nav-link" href="strategy.html"><span class="nav-link-icon d-md-none d-lg-inline-block"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"/><path d="M4 19l4 -6l4 2l4 -8l4 5"/><path d="M4 4v16h16"/></svg></span><span class="nav-link-title">Strategy P/L</span></a></li>
            <li class="nav-item"><a class="nav-link" href="tracker.html"><span class="nav-link-icon d-md-none d-lg-inline-block"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"/><path d="M12 12m-1 0a1 1 0 1 0 2 0a1 1 0 1 0 -2 0"/><path d="M12 12m-5 0a5 5 0 1 0 10 0a5 5 0 1 0 -10 0"/><path d="M12 12m-9 0a9 9 0 1 0 18 0a9 9 0 1 0 -18 0"/><path d="M15 12l-3 -3"/></svg></span><span class="nav-link-title">Tracker</span></a></li>
          </ul>
        </div>
      </div>
    </aside>

    <!-- Page -->
    <div class="page-wrapper">
      <div class="page-header d-print-none">
        <div class="container-xl">
          <div class="row g-2 align-items-center">
            <div class="col">
              <h2 class="page-title">Strategy P/L Analyzer</h2>
              <div class="text-secondary mt-1" x-show="legs.length > 0" x-cloak>
                <span class="badge bg-purple-lt fs-6 me-2" x-text="strategyName"></span>
                <span x-text="symbol"></span> ·
                <span x-text="legs.length + ' leg' + (legs.length===1?'':'s')"></span> ·
                Spot <strong class="mono" x-text="spot > 0 ? '$'+spot.toFixed(2) : '—'"></strong>
              </div>
            </div>
            <div class="col-auto" x-show="legs.length > 0" x-cloak>
              <button class="btn btn-outline-primary btn-sm me-1" @click="reloadMarket()" :disabled="refreshing" title="Re-fetch spot, marks &amp; IVs; refresh entry price on unlocked legs">
                <span x-show="refreshing" class="spinner-border spinner-border-sm me-1" role="status"></span>Reload
              </button>
              <button class="btn btn-outline-danger btn-sm" @click="clearAll()">Clear all</button>
            </div>
          </div>
        </div>
      </div>

      <div class="page-body">
        <div class="container-xl">

          <!-- Empty state -->
          <div class="card text-center py-5" x-show="legs.length === 0" x-cloak>
            <div class="card-body">
              <svg xmlns="http://www.w3.org/2000/svg" width="48" height="48" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" class="text-secondary mb-3"><path stroke="none" d="M0 0h24v24H0z" fill="none"/><path d="M4 19l4 -6l4 2l4 -8l4 5"/><path d="M4 4v16h16"/></svg>
              <h3 class="text-secondary">No strategy built yet</h3>
              <p class="text-muted">Go to the <a href="chain.html">Options Chain</a>, then click <span class="badge bg-success">B</span> (buy) or <span class="badge bg-danger">S</span> (sell) on options to add legs — or add one manually below.</p>
              <button class="btn btn-primary btn-sm mt-2" @click="showManual = !showManual">+ Add leg manually</button>
            </div>
          </div>

          <!-- P/L chart -->
          <div class="chart-card mb-3" x-show="legs.length > 0" x-cloak>
            <div class="card-header d-flex align-items-center justify-content-between flex-wrap gap-2">
              <h3 class="card-title text-white mb-0">Profit / Loss vs. Underlying Price</h3>
              <div class="d-flex align-items-center gap-2" style="min-width:320px;">
                <span class="text-secondary small text-nowrap">Now</span>
                <input type="range" class="form-range" min="0" :max="maxDTE" step="1" x-model.number="dteOffset" @input="scheduleRender()" style="min-width:160px;">
                <span class="text-secondary small text-nowrap">Exp</span>
                <span class="badge bg-blue-lt text-nowrap" x-text="dteLabel"></span>
              </div>
            </div>
            <div class="card-body p-0">
              <div id="plChart" style="min-height:380px;" role="img" aria-label="Profit and loss diagram"></div>
            </div>
          </div>

          <!-- Stats -->
          <div class="row g-2 mb-4" x-show="legs.length > 0" x-cloak>
            <div class="col-6 col-md-3 col-xl"><div class="stat-box"><div class="lbl">Net</div><div class="val" :class="netCost>=0?'neg':'pos'"><span x-text="netCost>=0?'Debit ':'Credit '"></span><span x-text="fmtMoney(Math.abs(netCost))"></span></div></div></div>
            <div class="col-6 col-md-3 col-xl"><div class="stat-box"><div class="lbl">Max Profit</div><div class="val pos" x-text="stats.maxProfit"></div></div></div>
            <div class="col-6 col-md-3 col-xl"><div class="stat-box"><div class="lbl">Max Loss</div><div class="val neg" x-text="stats.maxLoss"></div></div></div>
            <div class="col-6 col-md-3 col-xl"><div class="stat-box"><div class="lbl">Break-even(s)</div><div class="val amber mono" style="font-size:.95rem" x-text="stats.breakevens"></div></div></div>
            <div class="col-6 col-md-3 col-xl"><div class="stat-box"><div class="lbl">Net Δ (shares)</div><div class="val mono" :class="stats.delta>=0?'pos':'neg'" x-text="stats.delta.toFixed(1)"></div></div></div>
            <div class="col-6 col-md-3 col-xl"><div class="stat-box"><div class="lbl">Net Γ</div><div class="val mono" x-text="stats.gamma.toFixed(2)"></div></div></div>
            <div class="col-6 col-md-3 col-xl"><div class="stat-box"><div class="lbl">Net Θ / day</div><div class="val mono" :class="stats.theta>=0?'pos':'neg'" x-text="fmtMoney(stats.theta)"></div></div></div>
            <div class="col-6 col-md-3 col-xl"><div class="stat-box"><div class="lbl">Net Vega / 1%</div><div class="val mono" :class="stats.vega>=0?'pos':'neg'" x-text="fmtMoney(stats.vega)"></div></div></div>
          </div>

          <!-- Legs table (at the bottom) -->
          <div class="card mb-4" x-show="legs.length > 0 || showManual" x-cloak>
            <div class="card-header d-flex align-items-center justify-content-between">
              <h3 class="card-title mb-0">Legs <span class="text-secondary small fw-normal">— Mark = live mid · 🔒 locks entry price · uncheck to drop from chart</span></h3>
              <div>
                <span class="me-3" :class="netCost >= 0 ? 'text-danger' : 'text-success'">
                  Net <strong x-text="netCost >= 0 ? 'debit' : 'credit'"></strong>:
                  <strong class="mono" x-text="fmtMoney(Math.abs(netCost))"></strong>
                </span>
                <button class="btn btn-outline-primary btn-sm" @click="showManual = !showManual" x-text="showManual ? 'Hide manual entry' : '+ Add leg manually'"></button>
              </div>
            </div>
            <div class="table-responsive">
              <table class="table table-sm leg-table mb-0">
                <thead>
                  <tr>
                    <th class="text-center" style="width:3rem">Show</th>
                    <th>Side</th><th>Qty</th><th>Type</th><th class="text-end">Strike</th><th>Expiry</th>
                    <th class="text-end">Entry $</th><th class="text-end">Mark</th><th class="text-end">IV</th>
                    <th class="text-end">Cost</th><th class="text-end">Δ</th><th class="text-end">Θ/d</th><th></th>
                  </tr>
                </thead>
                <tbody>
                  <template x-for="lv in legsView" :key="lv.id">
                    <tr :style="lv.enabled === false ? 'opacity:.4' : ''">
                      <td class="text-center"><input type="checkbox" class="form-check-input m-0" :checked="lv.enabled !== false" @change="toggleLeg(lv.id)" :aria-label="'Show leg '+lv.strike+lv.type"></td>
                      <td style="width:7rem">
                        <select class="form-select form-select-sm" :value="lv.side" @change="updateLeg(lv.id, { side: $event.target.value })">
                          <option value="long">Long</option><option value="short">Short</option>
                        </select>
                      </td>
                      <td style="width:5rem"><input type="number" min="1" step="1" class="form-control form-control-sm" :value="lv.qty" @change="updateLeg(lv.id, { qty: Math.max(1, Math.round(+$event.target.value||1)) })"></td>
                      <td><span class="badge" :class="lv.type==='call' ? 'bg-success-lt text-success' : 'bg-danger-lt text-danger'" x-text="lv.type"></span></td>
                      <td class="text-end mono" x-text="lv.strike"></td>
                      <td class="mono small" x-text="lv.expiry"></td>
                      <td style="width:8.5rem">
                        <div class="input-group input-group-sm flex-nowrap">
                          <input type="number" min="0" step="0.01" class="form-control form-control-sm text-end" :class="lv.locked ? 'opacity-75' : ''" :value="lv.entryPrice" :disabled="lv.locked" @change="updateLeg(lv.id, { entryPrice: Math.max(0, +$event.target.value||0) })">
                          <button class="btn btn-sm btn-outline-secondary px-1" @click="updateLeg(lv.id, { locked: !lv.locked })" :title="lv.locked ? 'Entry price locked — click to unlock (reload will update it)' : 'Click to lock entry price (reload won\'t change it)'" x-text="lv.locked ? '🔒' : '🔓'"></button>
                        </div>
                      </td>
                      <td class="text-end mono small">
                        <template x-if="lv.currentMark != null">
                          <span>$<span x-text="lv.currentMark.toFixed(2)"></span><span x-show="Math.abs(lv.currentMark - lv.entryPrice) > 0.005" :class="(lv.currentMark - lv.entryPrice) >= 0 ? 'text-success' : 'text-danger'" x-text="(lv.currentMark - lv.entryPrice >= 0 ? ' +' : ' ') + (lv.currentMark - lv.entryPrice).toFixed(2)"></span></span>
                        </template>
                        <template x-if="lv.currentMark == null"><span class="text-secondary">—</span></template>
                      </td>
                      <td class="text-end mono small" x-text="lv.iv > 0 ? (lv.iv*100).toFixed(1)+'%' : '—'"></td>
                      <td class="text-end mono" :class="lv.cost >= 0 ? 'text-danger' : 'text-success'" x-text="fmtMoney(lv.cost)"></td>
                      <td class="text-end mono small" :class="lv.delta>=0?'text-success':'text-danger'" x-text="lv.delta.toFixed(1)"></td>
                      <td class="text-end mono small text-danger" x-text="lv.theta.toFixed(1)"></td>
                      <td class="text-end"><button class="btn btn-sm btn-ghost-danger" @click="removeLeg(lv.id)" aria-label="Remove leg">✕</button></td>
                    </tr>
                  </template>

                  <!-- Manual entry row -->
                  <template x-if="showManual">
                    <tr style="background:#161824;">
                      <td></td>
                      <td><select class="form-select form-select-sm" x-model="manual.side"><option value="long">Long</option><option value="short">Short</option></select></td>
                      <td><input type="number" min="1" step="1" class="form-control form-control-sm" x-model.number="manual.qty"></td>
                      <td><select class="form-select form-select-sm" x-model="manual.type"><option value="call">call</option><option value="put">put</option></select></td>
                      <td><input type="number" step="0.5" class="form-control form-control-sm text-end" placeholder="strike" x-model.number="manual.strike"></td>
                      <td><input type="date" class="form-control form-control-sm" x-model="manual.expiry"></td>
                      <td><input type="number" min="0" step="0.01" class="form-control form-control-sm text-end" placeholder="entry $" x-model.number="manual.entryPrice"></td>
                      <td></td>
                      <td><input type="number" min="0" step="0.5" class="form-control form-control-sm text-end" placeholder="IV %" x-model.number="manual.ivPct"></td>
                      <td colspan="4" class="text-end"><button class="btn btn-sm btn-primary" @click="addManualLeg()">Add leg</button></td>
                    </tr>
                  </template>
                </tbody>
              </table>
            </div>
          </div>

        </div>
      </div>
    </div>

    <!-- Toast -->
    <div class="toast-mini" x-show="toast" x-transition x-cloak>
      <div class="alert alert-success py-2 px-3 mb-0" x-text="toast"></div>
    </div>
  </div>

  <script src="/assets/tabler.min.js" defer></script>
  <script src="/assets/blackscholes.js"></script>
  <script src="/assets/strategy-store.js"></script>
  <script src="/assets/alpine.min.js" defer></script>

  <script>
    const R = 0.05;             // risk-free rate (matches backend)
    const MULT = 100;           // contract multiplier
    const DAY_MS = 86400000;

    const CHART_BG='#1e2030', CHART_GRID='#2d3045', CHART_LABEL='#8b95a7';
    const COLOR_EXP='#4dd4ac', COLOR_TN='#a98eda';

    function legDTE(leg) {
      // days from now to expiry; can be negative if expired
      const t = Date.parse(leg.expiry + 'T00:00:00Z');
      return (t - Date.now()) / DAY_MS;
    }
    function legSign(leg) { return leg.side === 'short' ? -1 : 1; }
    function legCost(leg) { return legSign(leg) * leg.qty * MULT * (leg.entryPrice || 0); }

    /** Value (per share) of a leg at underlying S, evaluated `offsetDays` from now. */
    function legValueAt(leg, S, offsetDays) {
      const remDays = legDTE(leg) - offsetDays;
      if (remDays <= 0) return BS.intrinsic(S, leg.strike, leg.type);
      const sigma = leg.iv > 0 ? leg.iv : 0.0001;
      return BS.bsPrice(S, leg.strike, remDays / 365, R, sigma, leg.type);
    }
    /** Position P/L at underlying S, evaluated `offsetDays` from now. */
    function plAt(legs, netCost, S, offsetDays) {
      let v = 0;
      for (const leg of legs) v += legSign(leg) * leg.qty * MULT * legValueAt(leg, S, offsetDays);
      return v - netCost;
    }

    function detectStrategy(legs) {
      const n = legs.length;
      if (n === 0) return 'Empty';
      const cap = s => s.charAt(0).toUpperCase() + s.slice(1);
      const sw = s => s === 'long' ? 'Long' : 'Short';
      if (n === 1) return `${sw(legs[0].side)} ${cap(legs[0].type)}`;
      const ls = [...legs].sort((a,b)=> a.type.localeCompare(b.type) || a.strike-b.strike || a.expiry.localeCompare(b.expiry));
      const allSameExp = ls.every(l => l.expiry === ls[0].expiry);
      const calls = ls.filter(l=>l.type==='call'), puts = ls.filter(l=>l.type==='put');
      if (n === 2) {
        const [a,b] = ls;
        if (a.type===b.type && a.expiry===b.expiry && a.side!==b.side && a.qty===b.qty) {
          const L = a.side==='long'?a:b, Sh = a.side==='long'?b:a;
          if (a.type==='call') return L.strike < Sh.strike ? 'Bull Call Spread (debit)' : 'Bear Call Spread (credit)';
          return L.strike > Sh.strike ? 'Bear Put Spread (debit)' : 'Bull Put Spread (credit)';
        }
        if (calls.length===1 && puts.length===1 && a.side===b.side && a.expiry===b.expiry)
          return calls[0].strike===puts[0].strike ? `${sw(a.side)} Straddle` : `${sw(a.side)} Strangle`;
        if (a.type===b.type && a.strike===b.strike && a.expiry!==b.expiry && a.side!==b.side) return 'Calendar Spread';
        if (a.type===b.type && a.strike!==b.strike && a.expiry!==b.expiry && a.side!==b.side) return 'Diagonal Spread';
        return 'Custom (2 legs)';
      }
      if (n === 3) {
        if (allSameExp && (calls.length===3 || puts.length===3)) {
          const [lo,mid,hi] = ls;
          if (lo.side===hi.side && lo.side!==mid.side && lo.qty===hi.qty && mid.qty===2*lo.qty)
            return `${lo.side==='long'?'Long':'Short'} ${cap(ls[0].type)} Butterfly`;
        }
        return 'Custom (3 legs)';
      }
      if (n === 4) {
        if (allSameExp && calls.length===2 && puts.length===2) {
          const [pL,pH] = puts, [cL,cH] = calls;
          const ic = pL.side==='long'&&pH.side==='short'&&cL.side==='short'&&cH.side==='long';
          if (ic && pH.strike===cL.strike) return 'Iron Butterfly';
          if (ic) return 'Iron Condor';
          const ric = pL.side==='short'&&pH.side==='long'&&cL.side==='long'&&cH.side==='short';
          if (ric) return 'Reverse Iron Condor';
        }
        if (allSameExp && calls.length===4) return 'Call Condor';
        if (allSameExp && puts.length===4) return 'Put Condor';
        return 'Custom (4 legs)';
      }
      return `Custom (${n} legs)`;
    }

    function fmtMoney(v) {
      if (v == null || !isFinite(v)) return '—';
      const sign = v < 0 ? '-' : '';
      const a = Math.abs(v);
      return sign + '$' + a.toLocaleString('en-US', { maximumFractionDigits: a < 100 ? 2 : 0 });
    }

    function strategyApp() {
      return {
        // state
        symbol: '', spot: 0, legs: [],
        dteOffset: 0,
        refreshing: false, showManual: false, toast: '',
        manual: { side:'long', type:'call', qty:1, strike:null, expiry:'', entryPrice:null, ivPct:null },
        chart: null, _renderTimer: null,

        init() {
          this.reload();
          // pull live spot / marks / IVs on open (does NOT touch entry prices)
          if (this.legs.length > 0 && this.symbol) this.reloadMarket(false);
          // re-sync if another tab changed the basket
          window.addEventListener('storage', (e) => { if (e.key === StrategyStore.KEY) this.reload(); });
        },

        reload() {
          const st = StrategyStore.load();
          this.symbol = st.symbol || '';
          this.spot = st.spotSnapshot || 0;
          this.legs = st.legs || [];
          if (this.dteOffset > this.maxDTE) this.dteOffset = this.maxDTE;
          if (this.legs.length > 0) this.$nextTick(() => this.renderChart());
        },

        // ── derived ───────────────────────────────────────────
        // only legs with the "Show" checkbox ticked drive the chart / stats / Greeks
        get activeLegs() { return this.legs.filter(l => l.enabled !== false); },
        get netCost() { return this.activeLegs.reduce((s,l)=> s + legCost(l), 0); },
        get strategyName() { return detectStrategy(this.activeLegs); },
        get maxDTE() { const a = this.activeLegs; return a.length ? Math.max(1, Math.ceil(Math.max(0, ...a.map(legDTE)))) : 1; },
        // exact (not floored) days to the earliest expiry — so the "expiration"
        // curve uses true intrinsic value (sharp hockey stick), not a near-expiry BS approx
        get minDTE() { const a = this.activeLegs; return a.length ? Math.max(0, Math.min(...a.map(legDTE))) : 0; },
        get dteLabel() {
          const d = new Date(Date.now() + this.dteOffset * DAY_MS);
          const ds = d.toISOString().slice(0,10);
          if (this.dteOffset === 0) return 'Today (' + ds + ')';
          return 'T+' + this.dteOffset + 'd · ' + ds;
        },

        get legsView() {
          return this.legs.map(l => {
            const dteY = Math.max(legDTE(l), 0) / 365;
            const sigma = l.iv > 0 ? l.iv : 0.0001;
            const g = (this.spot > 0)
              ? BS.bsGreeks(this.spot, l.strike, dteY, R, sigma, l.type)
              : { delta:0, gamma:0, theta:0, vega:0 };
            const k = legSign(l) * l.qty * MULT;
            return {
              ...l,
              cost: legCost(l),
              delta: g.delta * k,
              gamma: g.gamma * k,
              theta: g.theta * k,
              vega: g.vega * k,
            };
          });
        },

        get stats() {
          const legs = this.activeLegs, net = this.netCost, spot = this.spot;
          if (legs.length === 0) return { maxProfit:'—', maxLoss:'—', breakevens:'—', delta:0, gamma:0, theta:0, vega:0 };
          // dense expiration-curve sample for breakevens / extremes / unbounded
          const lo0 = 0.01;
          const hi0 = Math.max(spot * 2, ...legs.map(l=>l.strike)) * 1.5 + 10;
          const Nd = 600;
          const xs = [], ys = [];
          for (let i = 0; i <= Nd; i++) {
            const x = lo0 + (hi0 - lo0) * i / Nd;
            xs.push(x); ys.push(plAt(legs, net, x, this.minDTE));
          }
          // breakevens (sign changes)
          const bes = [];
          for (let i = 1; i <= Nd; i++) {
            const y0 = ys[i-1], y1 = ys[i];
            if (y0 === 0) { bes.push(xs[i-1]); continue; }
            if ((y0 < 0 && y1 > 0) || (y0 > 0 && y1 < 0)) {
              const x = xs[i-1] + (0 - y0) * (xs[i]-xs[i-1]) / (y1 - y0);
              bes.push(x);
            }
          }
          const uniqBE = bes.filter((v,i)=> i===0 || Math.abs(v - bes[i-1]) > 1e-6);
          // extremes — include the grid samples AND the exact kink points (strikes)
          // plus the sample bounds, since piecewise payoffs peak/trough at strikes
          let maxY = -Infinity, minY = Infinity;
          for (const y of ys) { if (y > maxY) maxY = y; if (y < minY) minY = y; }
          for (const k of new Set([...legs.map(l=>l.strike), lo0, hi0])) {
            const y = plAt(legs, net, k, this.minDTE);
            if (y > maxY) maxY = y; if (y < minY) minY = y;
          }
          // unbounded detection from the far-right slope of the expiration curve
          // (downside is always bounded since the underlying can't go below 0)
          const slopeR = (ys[Nd] - ys[Nd-1]) / (xs[Nd] - xs[Nd-1]);
          const maxProfit = slopeR >  1e-2 ? 'Unlimited' : fmtMoney(maxY);
          const maxLoss   = slopeR < -1e-2 ? 'Unlimited' : fmtMoney(minY);
          // net greeks now
          let d=0,g=0,t=0,v=0;
          for (const l of legs) {
            const dteY = Math.max(legDTE(l), 0) / 365;
            const sigma = l.iv > 0 ? l.iv : 0.0001;
            const gr = (spot>0) ? BS.bsGreeks(spot, l.strike, dteY, R, sigma, l.type) : {delta:0,gamma:0,theta:0,vega:0};
            const k = legSign(l) * l.qty * MULT;
            d += gr.delta*k; g += gr.gamma*k; t += gr.theta*k; v += gr.vega*k;
          }
          return {
            maxProfit, maxLoss,
            breakevens: uniqBE.length ? uniqBE.map(x=>'$'+x.toFixed(2)).join(' / ') : '—',
            delta:d, gamma:g, theta:t, vega:v,
          };
        },

        // ── actions ───────────────────────────────────────────
        updateLeg(id, patch) {
          StrategyStore.updateLeg(id, patch);
          this.reload();
        },
        toggleLeg(id) {
          const leg = this.legs.find(l => l.id === id);
          const cur = leg ? leg.enabled !== false : true;
          StrategyStore.updateLeg(id, { enabled: !cur });
          // refresh legs without resetting the date slider
          const st = StrategyStore.load();
          this.legs = st.legs || [];
          if (this.dteOffset > this.maxDTE) this.dteOffset = this.maxDTE;
          this.$nextTick(() => this.renderChart());
        },
        removeLeg(id) {
          StrategyStore.removeLeg(id);
          this.reload();
        },
        clearAll() {
          if (!confirm('Clear all legs?')) return;
          StrategyStore.clear();
          this.reload();
          if (this.chart) { this.chart.destroy(); this.chart = null; }
        },
        addManualLeg() {
          const m = this.manual;
          if (!m.strike || m.strike <= 0 || !m.expiry) { alert('Need a strike and expiry.'); return; }
          StrategyStore.addLeg({
            symbol: this.symbol || 'MANUAL',
            expiry: m.expiry, type: m.type, strike: +m.strike,
            side: m.side, qty: Math.max(1, Math.round(+m.qty||1)),
            entryPrice: Math.max(0, +m.entryPrice||0),
            iv: (+m.ivPct||0) / 100,
          });
          this.manual = { side:'long', type:'call', qty:1, strike:null, expiry:'', entryPrice:null, ivPct:null };
          this.reload();
          this.flash('Leg added');
        },
        // Re-fetch spot + each leg's current mark & IV.
        // When repriceUnlocked (default — the Reload button), unlocked legs also
        // get their entry price reset to the current mark; locked legs always keep it.
        async reloadMarket(repriceUnlocked = true) {
          if (!this.symbol || this.legs.length === 0) return;
          this.refreshing = true;
          try {
            const expiries = [...new Set(this.legs.map(l => l.expiry).filter(Boolean))];
            const byExpiry = {};   // expiry -> { strike@type -> option }
            let spot = 0;
            for (const exp of expiries) {
              const r = await fetch('/api/chain?symbol=' + encodeURIComponent(this.symbol) + '&expiry=' + encodeURIComponent(exp));
              if (!r.ok) continue;
              const e = await r.json();
              const snap = e.data?.snapshots?.[0];
              if (!snap) continue;
              if (snap.spot > 0) spot = snap.spot;
              const map = {};
              for (const o of (snap.chain || [])) {
                const t = (o.type || o.optionType || '').toLowerCase();
                map[Number(o.strike) + '@' + t] = o;
              }
              byExpiry[exp] = map;
            }
            const st = StrategyStore.load();
            let updated = 0, relinked = 0;
            for (const leg of st.legs) {
              const map = byExpiry[leg.expiry];
              if (!map) continue;
              const o = map[Number(leg.strike) + '@' + leg.type];
              if (!o) continue;
              const mark = Math.round((o.midPrice ?? o.mid ?? o.bsPrice ?? 0) * 100) / 100;
              leg.currentMark = mark;
              if (o.iv > 0) leg.iv = o.iv;
              if (!leg.locked && repriceUnlocked && mark > 0) { leg.entryPrice = mark; relinked++; }
              updated++;
            }
            if (spot > 0) st.spotSnapshot = spot;
            StrategyStore.save(st);
            this.legs = st.legs;
            if (spot > 0) this.spot = spot;
            if (this.dteOffset > this.maxDTE) this.dteOffset = this.maxDTE;
            this.$nextTick(() => this.renderChart());
            if (repriceUnlocked) {
              this.flash(updated > 0
                ? `Reloaded ${updated} leg${updated===1?'':'s'}${relinked?` (${relinked} re-priced)`:''} · spot $${(spot||this.spot).toFixed(2)}`
                : 'Reloaded — no matching contracts found in the current chain');
            }
          } catch (e) {
            if (repriceUnlocked) this.flash('Reload failed: ' + e.message);
          } finally {
            this.refreshing = false;
          }
        },
        flash(msg) { this.toast = msg; setTimeout(()=>{ this.toast=''; }, 2500); },

        scheduleRender() {
          clearTimeout(this._renderTimer);
          this._renderTimer = setTimeout(() => this.renderChart(), 40);
        },

        renderChart() {
          const legs = this.activeLegs, net = this.netCost;
          if (legs.length === 0) {
            if (this.chart) this.chart.updateSeries([{ name: 'P/L', data: [] }, { name: 'P/L', data: [] }]);
            return;
          }
          const spot = this.spot > 0 ? this.spot : (legs.reduce((s,l)=>s+l.strike,0)/legs.length);
          const strikes = legs.map(l=>l.strike);
          const minK = Math.min(...strikes), maxK = Math.max(...strikes);
          const span = maxK - minK;
          const half = Math.max(spot*0.22, span*1.5, (maxK-spot)*1.4, (spot-minK)*1.4, 5);
          const lo = Math.max(0.01, spot - half), hi = spot + half;
          const expAt = this.minDTE;
          const N = 161;
          // x-grid = evenly spaced points + the exact strike kinks (so payoff
          // vertices — butterfly peak, condor body, etc. — render sharply)
          const xGrid = [];
          for (let i = 0; i <= N; i++) xGrid.push(lo + (hi-lo)*i/N);
          for (const k of strikes) if (k > lo && k < hi) xGrid.push(k);
          xGrid.sort((a,b)=>a-b);
          const expData = [], tnData = [];
          let yMin = Infinity, yMax = -Infinity;
          for (const x of xGrid) {
            const ye = plAt(legs, net, x, expAt);
            const yt = plAt(legs, net, x, this.dteOffset);
            expData.push([x, +ye.toFixed(2)]);
            tnData.push([x, +yt.toFixed(2)]);
            yMin = Math.min(yMin, ye, yt); yMax = Math.max(yMax, ye, yt);
          }
          // Keep the chart readable when one tail is (near-)unbounded: don't let it
          // dominate the y-axis so badly the rest of the curve is a flat sliver.
          const aHi = Math.max(yMax, 0), aLo = Math.max(-yMin, 0);
          if (aLo > 1 && aHi > 6 * aLo) yMax = 6 * aLo;
          if (aHi > 1 && aLo > 6 * aHi) yMin = -6 * aHi;
          const pad = Math.max((yMax - yMin) * 0.08, 1);
          yMin -= pad; yMax += pad;

          // breakevens for light vertical lines
          const bes = [];
          for (let i = 1; i < expData.length; i++) {
            const y0 = expData[i-1][1], y1 = expData[i][1];
            if ((y0 < 0 && y1 > 0) || (y0 > 0 && y1 < 0)) {
              const x = expData[i-1][0] + (0 - y0) * (expData[i][0]-expData[i-1][0]) / (y1 - y0);
              bes.push(x);
            }
          }

          const xAnnos = [{
            x: spot, borderColor: '#ffd43b', strokeDashArray: 4,
            label: { text: 'Spot $'+spot.toFixed(2), borderColor:'#ffd43b', style:{ color:'#1a1c2e', background:'#ffd43b', fontSize:'11px' }, position:'top' }
          }].concat(bes.map(x => ({ x, borderColor:'#ffd43b66', strokeDashArray:2,
            label:{ text:'BE $'+x.toFixed(2), borderColor:'transparent', style:{ color:'#ffd43b', background:'#1a1c2e', fontSize:'10px' }, position:'bottom' } })));

          const opts = {
            chart: { type:'line', height:380, background:CHART_BG, foreColor:CHART_LABEL, fontFamily:'inherit', toolbar:{show:false}, animations:{enabled:false}, zoom:{enabled:false} },
            series: [
              { name: this.dteOffset===0 ? 'P/L Today' : 'P/L '+this.dteLabel, type:'line', data: tnData, color: COLOR_TN },
              { name: 'P/L at Expiration', type:'line', data: expData, color: COLOR_EXP },
            ],
            stroke: { width:[2,3], curve:['smooth','straight'], dashArray:[5,0] },
            markers: { size:0 },
            grid: { borderColor:CHART_GRID, strokeDashArray:3 },
            dataLabels: { enabled:false },
            legend: { labels:{ colors:'#d0d5e0' }, position:'top', horizontalAlign:'right' },
            xaxis: {
              type:'numeric', tickAmount:10,
              labels:{ style:{colors:CHART_LABEL}, formatter:v=>'$'+Number(v).toFixed(0) },
              title:{ text:'Underlying price', style:{color:CHART_LABEL} },
              axisBorder:{color:CHART_GRID}, axisTicks:{color:CHART_GRID},
            },
            yaxis: {
              min:yMin, max:yMax,
              labels:{ style:{colors:CHART_LABEL}, formatter:v=>fmtMoney(v) },
              title:{ text:'Profit / Loss ($)', style:{color:CHART_LABEL} },
            },
            tooltip: {
              theme:'dark', shared:true, intersect:false,
              x:{ formatter:v=>'Underlying $'+Number(v).toFixed(2) },
              y:{ formatter:v=>fmtMoney(v) },
            },
            annotations: {
              yaxis: [
                { y:0, y2:yMax, fillColor:'#2fb344', opacity:0.05, borderColor:'transparent' },
                { y:yMin, y2:0, fillColor:'#d63939', opacity:0.05, borderColor:'transparent' },
                { y:0, borderColor:'#9aa4b2', strokeDashArray:0, label:{ text:'Break-even', borderColor:'transparent', style:{color:'#9aa4b2', background:'transparent', fontSize:'10px'}, position:'left' } },
              ],
              xaxis: xAnnos,
            },
          };

          if (this.chart) {
            this.chart.updateOptions(opts, true, false);
          } else {
            this.chart = new ApexCharts(document.getElementById('plChart'), opts);
            this.chart.render();
          }
        },

        fmtMoney,
      };
    }
  </script>
</body>
</html>