/* shared.js -- common runtime for all module pages:
   top navigation, Pyodide bootstrap, editable-code runner, plot helpers. */

const NAV_ITEMS = [
  ["index.html", "导航 Home"],
  ["m00_overview.html", "0 水量平衡"],
  ["m01_forcing.html", "1 Forcing"],
  ["m02_pet.html", "2 PET"],
  ["m05_runoff.html", "5 产流"],
  ["m06_response.html", "6 Response"],
  ["m07_routing.html", "7 Routing·方法"],
  ["m08_channel.html", "8a Routing·空间"],
];

function renderNav(here) {
  const nav = document.createElement("div");
  nav.className = "topnav";
  const inner = document.createElement("div");
  inner.className = "wrap";
  const brand = document.createElement("span");
  brand.className = "brand";
  brand.textContent = "💧 HydroModel Builder";
  inner.appendChild(brand);
  for (const [href, label] of NAV_ITEMS) {
    // skip links to pages that don't exist yet (marked with data-disabled below)
    const a = document.createElement("a");
    a.href = href;
    a.textContent = label;
    if (here === href) a.className = "here";
    inner.appendChild(a);
  }
  nav.appendChild(inner);
  document.body.prepend(nav);
}

/* ---------- Pyodide bootstrap (one shared promise) ---------- */
let _pyodidePromise = null;
function getPyodide(statusEl) {
  if (!_pyodidePromise) {
    if (statusEl) statusEl.textContent = "正在加载 Python 运行时 (~10s 首次) …";
    _pyodidePromise = loadPyodide().then(async (py) => {
      await py.loadPackage("numpy");
      if (statusEl) statusEl.textContent = "Python (numpy) 就绪 — 可改代码后重跑";
      return py;
    });
  }
  return _pyodidePromise;
}

/* ---------- Editable-code runner ----------
   makeRunner({codeEl, runBtn, resetBtn, statusEl, errEl, buildScript, onResult})
   - codeEl: <textarea> holding user-editable Python
   - buildScript(userCode, params) -> full python source to exec; must set __out
   - onResult(jsValue, params): update plots/readouts
   - params(): collect current slider values                              */
function makeRunner(cfg) {
  const defaultCode = cfg.codeEl.value;
  async function run() {
    const py = await getPyodide(cfg.statusEl);
    if (cfg.errEl) cfg.errEl.innerHTML = "";
    cfg.runBtn.disabled = true;
    try {
      const params = cfg.params ? cfg.params() : {};
      const src = cfg.buildScript(cfg.codeEl.value, params);
      const t0 = performance.now();
      py.runPython(src);
      const ms = performance.now() - t0;
      const out = py.globals.get("__out");
      const js = out.toJs({ dict_converter: Object.fromEntries });
      if (out.destroy) out.destroy();
      cfg.onResult(js, params, ms);
    } catch (e) {
      if (cfg.errEl)
        cfg.errEl.innerHTML =
          '<div class="err">运行出错 / error:\n' + (e && e.message ? e.message : e) + "</div>";
    } finally {
      cfg.runBtn.disabled = false;
    }
  }
  cfg.runBtn.addEventListener("click", run);
  if (cfg.resetBtn)
    cfg.resetBtn.addEventListener("click", () => {
      cfg.codeEl.value = defaultCode;
      run();
    });
  if (cfg.autorun !== false) getPyodide(cfg.statusEl).then(run);
  return run;
}

/* ---------- slider helper: live label + rerun on release ---------- */
function bindSlider(id, labelId, fmt, onchange) {
  const el = document.getElementById(id);
  const lab = document.getElementById(labelId);
  const f = fmt || ((v) => v);
  const upd = () => (lab.textContent = f(parseFloat(el.value)));
  el.addEventListener("input", upd);
  if (onchange) el.addEventListener("change", onchange);
  upd();
  return el;
}

/* ---------- plot helpers ---------- */
const PLOT_CFG = { responsive: true, displayModeBar: false };
function linePlot(div, traces, ylab, xlab, extra) {
  Plotly.react(
    div,
    traces,
    Object.assign(
      {
        margin: { t: 10, r: 10, b: 40, l: 55 },
        legend: { orientation: "h", y: 1.13 },
        xaxis: { title: xlab || "day" },
        yaxis: { title: ylab || "" },
      },
      extra || {}
    ),
    PLOT_CFG
  );
}

/* version tabs: makeTabs(containerId, [{key,label,crest}], onSwitch) */
function makeTabs(containerId, versions, onSwitch) {
  const box = document.getElementById(containerId);
  box.className = "vtabs";
  let current = versions[0].key;
  for (const v of versions) {
    const b = document.createElement("button");
    b.innerHTML = v.label + (v.crest ? '<span class="crest-mini">CREST</span>' : "");
    b.dataset.key = v.key;
    if (v.key === current) b.className = "on";
    b.addEventListener("click", () => {
      current = v.key;
      for (const c of box.children) c.className = c.dataset.key === current ? "on" : "";
      onSwitch(current);
    });
    box.appendChild(b);
  }
  return () => current;
}

function footer() {
  const f = document.createElement("div");
  f.className = "foot";
  f.innerHTML =
    'Made with Claude Code · hydrologic-model-builder skill · data: TU Delft CIE4431 Hesperange · anchor: <a href="https://github.com/HyDROSLab/EF5">CREST/EF5</a>';
  document.querySelector(".wrap:last-of-type")?.appendChild(f) || document.body.appendChild(f);
}