import { useEffect, useMemo, useRef, useState } from "react";
import { Link, useParams } from "react-router";

import { logout } from "wasp/client/auth";
import { getSpec, resetSection, updateSection, useQuery } from "wasp/client/operations";

import { SECTION_TEMPLATES, isSectionDone } from "./sections.js";
import "./styles.css";

export const SpecPage = ({ user }) => {
  const { id } = useParams();
  const specId = Number(id);
  const { data: spec, isLoading, error } = useQuery(getSpec, { id: specId });

  const [drafts, setDrafts] = useState({});
  const [current, setCurrent] = useState(0);
  const [mode, setMode] = useState("edit");
  const [saveState, setSaveState] = useState("idle");
  const timerRef = useRef(null);

  // Seed drafts from the server exactly once per loaded section.
  useEffect(() => {
    if (spec?.sections) {
      setDrafts((prev) => {
        const next = { ...prev };
        spec.sections.forEach((s) => {
          if (next[s.key] === undefined) next[s.key] = s.content;
        });
        return next;
      });
    }
  }, [spec]);

  const sections = spec?.sections ?? [];
  const sec = sections[current];

  const doneCount = useMemo(
    () => sections.filter((s) => isSectionDone(drafts[s.key])).length,
    [sections, drafts]
  );

  const handleChange = (value) => {
    if (!sec) return;
    setDrafts((d) => ({ ...d, [sec.key]: value }));
    setSaveState("saving");
    clearTimeout(timerRef.current);
    timerRef.current = setTimeout(async () => {
      try {
        await updateSection({ specId, key: sec.key, content: value });
        setSaveState("saved");
      } catch (err) {
        setSaveState("error");
      }
    }, 700);
  };

  const markdown = useMemo(() => {
    if (!spec) return "";
    return (
      `# Tech Spec — ${spec.title}\n\n` +
      sections
        .map((s, i) => `## ${i + 1}. ${s.title}\n\n${(drafts[s.key] ?? s.content).trim()}`)
        .join("\n\n---\n\n")
    );
  }, [spec, sections, drafts]);

  if (isLoading) {
    return <div className="wrap lede">Loading…</div>;
  }
  if (error) {
    return <div className="wrap"><p className="lede">Error: {error.message}</p><Link to="/">← Back</Link></div>;
  }
  if (!spec) return null;

  return (
    <div className="app">
      <header className="topbar">
        <Link to="/" className="logo row" style={{ textDecoration: "none", color: "inherit" }}>
          <div className="logo-mark" />SpecForge
        </Link>
        <span className={"chip" + (doneCount === sections.length ? " ready" : "")}>
          {doneCount}/{sections.length}{doneCount === sections.length ? " · ready for harness" : ""}
        </span>
        <div className="sp" />
        <button className="btn" onClick={() => setMode(mode === "edit" ? "preview" : "edit")}>
          {mode === "edit" ? "Preview" : "Edit"}
        </button>
        <button className="btn primary" onClick={() => copyToClipboard(markdown)}>Copy Markdown</button>
        <button className="btn" onClick={logout}>Logout</button>
      </header>
      <div className="wrap">
        <div className="editor">
          <nav className="sidenav">
            {sections.map((s, i) => (
              <button key={s.key} className={"secbtn" + (i === current ? " on" : "")} onClick={() => setCurrent(i)}>
                <span className={"dot" + (isSectionDone(drafts[s.key]) ? " done" : "")} />
                {s.title}
              </button>
            ))}
          </nav>
          <div className="pane">
            <div className="kick">Section {String(current + 1).padStart(2, "0")} of {sections.length}</div>
            <div className="h1" style={{ fontSize: 18 }}>{sec?.title}</div>
            <div className="hint">{sec?.hint}</div>
            {mode === "edit" ? (
              <textarea value={drafts[sec?.key] ?? ""} onChange={(e) => handleChange(e.target.value)} spellCheck="false" />
            ) : (
              <div className="preview">{drafts[sec?.key] ?? ""}</div>
            )}
            <div className="statusline">
              <span>{wordCount(drafts[sec?.key])} words</span>
              {saveState === "saving" && <span>saving…</span>}
              {saveState === "saved" && <span className="saved">✓ saved</span>}
              {saveState === "error" && <span style={{ color: "var(--warn)" }}>save failed</span>}
              <div className="sp" />
              <button
                className="btn"
                onClick={async () => {
                  if (!sec) return;
                  const template = SECTION_TEMPLATES.find((t) => t.key === sec.key);
                  await resetSection({ specId, key: sec.key }).catch((e) => window.alert(e.message));
                  setDrafts((d) => ({ ...d, [sec.key]: template?.starter ?? d[sec.key] }));
                }}
              >
                Reset section
              </button>
              <button className="btn" onClick={() => setCurrent((current + sections.length - 1) % sections.length)}>← Prev</button>
              <button className="btn" onClick={() => setCurrent((current + 1) % sections.length)}>Next →</button>
            </div>
          </div>
        </div>
        <p className="lede" style={{ marginTop: 14, fontSize: 12 }}>
          Signed in as {user?.identities?.username?.id} · spec #{spec.id} · every edit autosaves to the database.
        </p>
      </div>
    </div>
  );
};

function wordCount(text) {
  const t = (text ?? "").trim();
  return t ? t.split(/\s+/).length : 0;
}

async function copyToClipboard(text) {
  try {
    await navigator.clipboard.writeText(text);
    toast("Copied full spec as Markdown — paste into a .md file");
  } catch {
    toast("Clipboard blocked — select the preview text manually");
  }
}

function toast(msg) {
  let el = document.querySelector(".toast");
  if (!el) {
    el = document.createElement("div");
    el.className = "toast";
    document.body.appendChild(el);
  }
  el.textContent = msg;
  el.classList.add("show");
  setTimeout(() => el.classList.remove("show"), 2000);
}