import { useEffect, useMemo, useRef, useState } from "react";
import { FileText, ArrowRight, Sliders } from "@phosphor-icons/react";
import {
  api, inr, ApiError,
  type DraftSection, type IssueTerms, type RunSummary,
} from "../lib/api";
import { CitationPopover, Empty, ErrorNote, Note, Spinner, TableSkeleton } from "./common";

export function Draft({
  run, onNext, onRunUpdate,
}: { run: RunSummary; onNext: () => void; onRunUpdate: (r: RunSummary) => void }) {
  const [sections, setSections] = useState<DraftSection[] | null>(null);
  const [issue, setIssue] = useState<IssueTerms | null>(null);
  const [active, setActive] = useState<string>("");
  const [error, setError] = useState<string | null>(null);
  const [busy, setBusy] = useState(false);
  const docRef = useRef<HTMLDivElement>(null);

  const load = async () => {
    setError(null);
    setSections(null);
    try {
      const [d, t] = await Promise.all([api.draft(run.id), api.getIssue(run.id)]);
      setSections(d.sections);
      setIssue(t);
      setActive(d.sections[0]?.id ?? "");
      onRunUpdate(d);
    } catch (e) {
      setError(e instanceof ApiError ? e.message : String(e));
    }
  };
  useEffect(() => { load(); }, [run.id]);

  const current = useMemo(
    () => sections?.find((s) => s.id === active) ?? sections?.[0],
    [sections, active],
  );

  const saveIssue = async (next: IssueTerms) => {
    setBusy(true);
    try {
      const saved = await api.putIssue(run.id, next);
      setIssue(saved);
      const d = await api.draft(run.id);
      setSections(d.sections);
      onRunUpdate(d);
    } catch (e) {
      setError(e instanceof ApiError ? e.message : String(e));
    } finally {
      setBusy(false);
    }
  };

  return (
    <>
      <div className="page-head">
        <h1 className="page">Offer document draft</h1>
        <p className="lede">
          Drafted from the ledger alone. Templates carry tokens, never figures, so a number that
          is not bound to a sourced fact cannot reach the page. Hover any figure to see the filing
          and page it came from. Figures in grey dashes are your proposed issue terms, not facts
          about the issuer.
        </p>
      </div>

      {error && <div style={{ marginBottom: 14 }}><ErrorNote message={error} onRetry={load} /></div>}

      <div className="grid cols-sidebar">
        <div className="doc-wrap">
          <nav className="panel toc">
            <div className="panel-h"><h2>Sections</h2></div>
            <div style={{ padding: "6px 0" }}>
              {!sections && <div style={{ padding: 12 }}><TableSkeleton rows={6} /></div>}
              {sections?.map((s) => (
                <button
                  key={s.id}
                  aria-current={s.id === active}
                  onClick={() => { setActive(s.id); docRef.current?.scrollTo({ top: 0 }); }}
                >
                  <span className="toc-n">{s.number}</span>
                  {s.title}
                </button>
              ))}
            </div>
          </nav>

          <div>
            {!sections ? (
              <div className="panel"><div className="panel-b"><TableSkeleton rows={12} /></div></div>
            ) : !current ? (
              <div className="panel">
                <Empty title="No draft yet">The draft has not been generated.</Empty>
              </div>
            ) : (
              <div className="doc" ref={docRef}>
                <h3>{current.number}. {current.title}</h3>
                <div className="clause">{current.icdr_clause}</div>
                <div dangerouslySetInnerHTML={{ __html: current.html }} />
                <div style={{
                  marginTop: 22, paddingTop: 14, borderTop: "1px solid var(--line)",
                  fontSize: 11.5, color: "var(--text-3)", fontFamily: "var(--mono)",
                }}>
                  {current.word_count} words · {current.fact_ids.length} sourced figures ·
                  narrative from {current.narrative_source}
                </div>
              </div>
            )}
            <CitationPopover container={docRef} />
          </div>
        </div>

        <aside style={{ display: "grid", gap: 14 }}>
          <section className="panel">
            <div className="panel-h">
              <Sliders size={16} />
              <h2>Proposed issue terms</h2>
            </div>
            <div className="panel-b">
              {!issue ? <TableSkeleton rows={5} /> : (
                <IssueForm issue={issue} busy={busy} onSave={saveIssue} />
              )}
            </div>
          </section>

          <Note tone="quiet">
            These terms are your input as merchant banker. They are recorded separately from the
            disclosure ledger and never treated as facts about the issuer. The engine checks them
            against the issuer's real financials and against the SME limits.
          </Note>

          <button className="btn btn-primary" onClick={onNext} disabled={!sections}
                  style={{ justifyContent: "center", padding: "11px 18px" }}>
            Run the consistency engine <ArrowRight size={15} />
          </button>
        </aside>
      </div>
    </>
  );
}

function IssueForm({
  issue, busy, onSave,
}: { issue: IssueTerms; busy: boolean; onSave: (t: IssueTerms) => void }) {
  const [d, setD] = useState(issue);
  useEffect(() => setD(issue), [issue]);

  const num = (k: keyof IssueTerms) => ({
    value: String(d[k] ?? 0),
    onChange: (e: React.ChangeEvent<HTMLInputElement>) =>
      setD({ ...d, [k]: Number(e.target.value) || 0 }),
  });

  const gross = d.fresh_issue_shares * d.price_per_share;
  const net = gross - d.issue_expenses;
  const objTotal = d.objects.reduce((a, o) => a + o.amount, 0);
  const gap = objTotal - net;

  return (
    <>
      <div className="field">
        <label htmlFor="px">Issue price per share</label>
        <input id="px" className="ctl" type="number" {...num("price_per_share")} />
      </div>
      <div className="field">
        <label htmlFor="fresh">Fresh issue shares</label>
        <input id="fresh" className="ctl" type="number" {...num("fresh_issue_shares")} />
        <div className="help">Gross proceeds {inr(gross)}</div>
      </div>
      <div className="field">
        <label htmlFor="ofs">Offer for sale shares</label>
        <input id="ofs" className="ctl" type="number" {...num("ofs_shares")} />
        <div className="help">
          {inr(d.ofs_shares * d.price_per_share)}, capped at 20% of the issue for an SME
        </div>
      </div>
      <div className="field">
        <label htmlFor="exp">Estimated issue expenses</label>
        <input id="exp" className="ctl" type="number" {...num("issue_expenses")} />
        <div className="help">Net proceeds {inr(net)}</div>
      </div>

      <div style={{ borderTop: "1px solid var(--line)", paddingTop: 12, marginTop: 4 }}>
        <div style={{ fontSize: 12, fontWeight: 500, color: "var(--text-2)", marginBottom: 8 }}>
          Objects of the issue
        </div>
        {d.objects.map((o, i) => (
          <div className="obj-row" key={o.id}>
            <span className="lbl">{o.label}</span>
            <input
              className="ctl"
              type="number"
              aria-label={o.label}
              value={String(o.amount)}
              onChange={(e) => {
                const objects = [...d.objects];
                objects[i] = { ...o, amount: Number(e.target.value) || 0 };
                setD({ ...d, objects });
              }}
            />
          </div>
        ))}
        <div style={{
          display: "flex", justifyContent: "space-between", fontSize: 12,
          marginTop: 8, paddingTop: 8, borderTop: "1px solid var(--line-soft)",
        }}>
          <span style={{ color: "var(--text-2)" }}>Objects total</span>
          <span className="num" style={{ fontWeight: 600 }}>{inr(objTotal)}</span>
        </div>
        <div style={{ display: "flex", justifyContent: "space-between", fontSize: 12, marginTop: 4 }}>
          <span style={{ color: "var(--text-2)" }}>Net proceeds available</span>
          <span className="num" style={{ fontWeight: 600 }}>{inr(net)}</span>
        </div>
        {Math.abs(gap) > 1 && (
          <div className="delta" style={{ marginTop: 8 }}>
            {gap > 0 ? "over by " : "short by "}{inr(Math.abs(gap))}
          </div>
        )}
      </div>

      <button
        className="btn btn-ghost btn-sm"
        style={{ width: "100%", justifyContent: "center", marginTop: 10 }}
        onClick={() => onSave(d)}
        disabled={busy}
      >
        {busy ? <><Spinner /> Redrafting</> : "Apply terms and redraft"}
      </button>
    </>
  );
}