"use strict";
// Compare view: line up several places over one date range and see which best
// matches a comfort temperature. For each location we pull the same daily record
// the Calendar uses (api/v2/calendar) and, per day, take a chosen temperature
// (daytime high / daily mean / overnight low / feels-like) and measure it against
// the comfort target. A day "hits comfort" when it lands within a tolerance band;
// otherwise it's colder or warmer, and we track by how much.
//
// The whole comparison — locations, comfort target, band, judged temperature and
// date range — lives in the URL hash, so a link reproduces exactly what you see.
// Comfort / band / judged-temperature re-rank instantly (all values are already in
// hand). Editing the date range or the location set doesn't refetch on its own:
// it arms the Refresh button, and the load runs when the user taps it.

const CMP = {
  comfort: "thermograph:cmpComfort",
  tol: "thermograph:cmpTol",
  basis: "thermograph:cmpBasis",
  range: "thermograph:cmpRange",
  locs: "thermograph:cmpLocs",
};

const lsGet = (k) => { try { return localStorage.getItem(k); } catch (e) { return null; } };
const lsSet = (k, v) => { try { localStorage.setItem(k, v); } catch (e) {} };

const clamp = (v, lo, hi) => Math.min(hi, Math.max(lo, v));
const BASES = ["tmax", "tmin", "mean", "feels"];
let comfort = clamp(+lsGet(CMP.comfort) || 68, 30, 100);
let tol = clamp(lsGet(CMP.tol) == null ? 5 : +lsGet(CMP.tol), 0, 15);
let basis = BASES.includes(lsGet(CMP.basis)) ? lsGet(CMP.basis) : "tmax";

// Locations being compared: {lat, lon, name, series|null, loading, error}.
// `series` is a compact per-day array of {hi, lo, feels} (°F, any may be null).
// A location with no series and not loading is "pending" — it needs a Refresh tap.
let locations = [];
// Bumped on every (re)load so a superseded in-flight fetch drops its result.
let loadToken = 0;

const BASIS_LABEL = { tmax: "daytime high", mean: "daily mean", tmin: "overnight low", feels: "feels-like" };

// ---- date range (month granularity) ----
const pad = (n) => String(n).padStart(2, "0");
const isYM = (s) => typeof s === "string" && /^\d{4}-\d{2}$/.test(s);
function defaultRange() {
  const now = new Date();
  const s = new Date(now.getFullYear(), now.getMonth() - 11, 1);   // last 12 whole months
  return { start: `${s.getFullYear()}-${pad(s.getMonth() + 1)}`, end: `${now.getFullYear()}-${pad(now.getMonth() + 1)}` };
}
function loadRange() {
  try { const o = JSON.parse(lsGet(CMP.range)); if (o && isYM(o.start) && isYM(o.end)) return o; } catch (e) {}
  return defaultRange();
}
let range = loadRange();   // the APPLIED range (what loaded data reflects), "YYYY-MM"

const monthStart = (ym) => `${ym}-01`;
const isoOfDate = (d) => `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
const monthEnd = (ym) => isoOfDate(new Date(+ym.slice(0, 4), +ym.slice(5, 7), 0));

// Pretty "Jul 2025 – Jun 2026" for a YYYY-MM range.
const MON = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
const monthLabel = (ym) => `${MON[+ym.slice(5, 7) - 1]} ${ym.slice(0, 4)}`;

// Split a [startIso, endIso] span into consecutive ≤2-year windows so each stays
// within the calendar endpoint's per-request cap (mirrors the Calendar view).
const CHUNK_MONTHS = 24;
function buildChunks(startIso, endIso) {
  const out = [];
  let s = startIso, guard = 0;
  while (s <= endIso && guard++ < 200) {
    const sd = new Date(s + "T00:00:00");
    const ed = new Date(sd.getFullYear(), sd.getMonth() + CHUNK_MONTHS, sd.getDate());
    ed.setDate(ed.getDate() - 1);
    let e = isoOfDate(ed);
    if (e > endIso) e = endIso;
    out.push({ start: s, end: e });
    const ns = new Date(e + "T00:00:00"); ns.setDate(ns.getDate() + 1);
    s = isoOfDate(ns);
  }
  return out;
}

// ---- shareable URL state ----
// The hash carries the full comparison: c=comfort, t=band, b=basis, s/e=range,
// loc=lat,lon;lat,lon. Written on every state change; read once on load (a link
// wins over localStorage). A plain lat/lon hash from cross-view nav is ignored
// here and handled by the seed path instead.
function writeHashState() {
  const p = new URLSearchParams();
  p.set("c", comfort); p.set("t", tol); p.set("b", basis);
  p.set("s", range.start); p.set("e", range.end);
  if (locations.length) p.set("loc", locations.map((l) => `${l.lat.toFixed(4)},${l.lon.toFixed(4)}`).join(";"));
  history.replaceState(null, "", "#" + p.toString());
}
function readHashState() {
  const p = new URLSearchParams(location.hash.slice(1));
  if (!["c", "t", "b", "s", "e", "loc"].some((k) => p.has(k))) return null;   // not a compare link
  const st = {};
  if (p.has("c")) st.comfort = clamp(+p.get("c") || 68, 30, 100);
  if (p.has("t") && p.get("t") !== "") st.tol = clamp(+p.get("t"), 0, 15);
  if (BASES.includes(p.get("b"))) st.basis = p.get("b");
  if (isYM(p.get("s"))) st.start = p.get("s");
  if (isYM(p.get("e"))) st.end = p.get("e");
  if (p.has("loc")) {
    st.locs = p.get("loc").split(";").map((pair) => {
      const [a, b] = pair.split(",").map(Number);
      return { lat: a, lon: b };
    }).filter((l) => !isNaN(l.lat) && !isNaN(l.lon));
  }
  return st;
}

// ---- elements ----
const addBtn = document.getElementById("cmp-add");
const refreshBtn = document.getElementById("cmp-refresh");
const locList = document.getElementById("cmp-loc-list");
const params = document.getElementById("cmp-params");
const placeholder = document.getElementById("cmp-placeholder");
const head = document.getElementById("cmp-head");
const results = document.getElementById("cmp-results");
const comfortInput = document.getElementById("cmp-comfort");
const comfortVal = document.getElementById("cmp-comfort-val");
const tolInput = document.getElementById("cmp-tol");
const tolVal = document.getElementById("cmp-tol-val");
const basisToggle = document.getElementById("cmp-basis");
const startInput = document.getElementById("cmp-start");
const endInput = document.getElementById("cmp-end");

addBtn.innerHTML = `${window.LocationPicker.PIN_ICON} <span>Add location</span>`;

// ---- data ----
// Fetch one location's range (chunked) and reduce it to the compact per-day series.
async function fetchSeries(loc, token) {
  const chunks = buildChunks(monthStart(range.start), monthEnd(range.end));
  const days = [];
  let place = null;
  for (const ch of chunks) {
    const url = `api/v2/calendar?lat=${loc.lat}&lon=${loc.lon}&start=${ch.start}&end=${ch.end}`;
    const d = await window.Thermograph.getJSON(url, window.Thermograph.TTL.calendar, true);
    if (token !== loadToken) return null;   // superseded
    place = place || d.place || `${d.cell.center_lat.toFixed(2)}, ${d.cell.center_lon.toFixed(2)}`;
    for (const r of d.days) days.push(r);
  }
  return {
    name: place,
    series: days.map((r) => ({
      hi: r.tmax ? r.tmax.v : null,
      lo: r.tmin ? r.tmin.v : null,
      feels: r.feels ? r.feels.v : null,
    })),
  };
}

function persistLocations() {
  lsSet(CMP.locs, JSON.stringify(locations.map((l) => ({ lat: l.lat, lon: l.lon, name: l.name }))));
}

async function loadLocation(loc, token) {
  loc.loading = true; loc.error = null;
  renderAll();
  try {
    const res = await fetchSeries(loc, token);
    if (!res || token !== loadToken) return;   // superseded (a newer load owns this loc)
    loc.name = res.name; loc.series = res.series;
  } catch (e) {
    if (token === loadToken) loc.error = e.message || "couldn't load";
  }
  if (token === loadToken) loc.loading = false;
  persistLocations();
  renderAll();
}

// Load every location that still needs data under the current range.
function loadPending(token) {
  for (const loc of locations) if (!loc.series && !loc.loading) loadLocation(loc, token);
}

function addLocation(lat, lon) {
  // Ignore a spot already on the list (same grid neighborhood).
  if (locations.some((l) => Math.abs(l.lat - lat) < 0.05 && Math.abs(l.lon - lon) < 0.05)) return;
  locations.push({ lat, lon, name: null, series: null, loading: false, error: null });
  window.Thermograph.saveLastLocation(lat, lon);
  persistLocations();
  writeHashState();
  renderAll();   // pending → the Refresh button appears; no fetch until it's tapped
}

function removeLocation(i) {
  locations.splice(i, 1);
  persistLocations();
  writeHashState();
  renderAll();
}

// ---- pending / refresh state ----
const dateChanged = () => startInput.value !== range.start || endInput.value !== range.end;
const isPending = (l) => !l.series && !l.loading && !l.error;
const isDirty = () => locations.length > 0 && (dateChanged() || locations.some(isPending));

// The Refresh tap: adopt any edited dates (which invalidates every series) and load
// whatever now needs data.
function refresh() {
  let s = startInput.value || range.start, e = endInput.value || range.end;
  if (!isYM(s) || !isYM(e)) return;
  if (s > e) { const t = s; s = e; e = t; }
  const rangeChanged = s !== range.start || e !== range.end;
  range = { start: s, end: e };
  startInput.value = s; endInput.value = e;
  lsSet(CMP.range, JSON.stringify(range));
  const token = ++loadToken;
  if (rangeChanged) for (const loc of locations) loc.series = null;
  writeHashState();
  loadPending(token);
  renderAll();
}

// ---- stats ----
function basisTemp(pt) {
  if (basis === "tmax") return pt.hi;
  if (basis === "tmin") return pt.lo;
  if (basis === "feels") return pt.feels;
  return pt.hi != null && pt.lo != null ? (pt.hi + pt.lo) / 2 : null;   // mean
}

function computeStats(series) {
  let n = 0, below = 0, above = 0, comf = 0, sumBelow = 0, sumAbove = 0, sumAbs = 0;
  for (const pt of series) {
    const t = basisTemp(pt);
    if (t == null || isNaN(t)) continue;
    n++;
    const d = t - comfort;
    sumAbs += Math.abs(d);
    if (d < -tol) { below++; sumBelow += -d; }
    else if (d > tol) { above++; sumAbove += d; }
    else comf++;
  }
  if (!n) return null;
  return {
    n, comf, below, above,
    comfortPct: 100 * comf / n, belowPct: 100 * below / n, abovePct: 100 * above / n,
    avgBelow: below ? sumBelow / below : 0,
    avgAbove: above ? sumAbove / above : 0,
    mad: sumAbs / n,
  };
}

// ---- render ----
const pct = (v) => `${v < 10 ? v.toFixed(1) : Math.round(v)}%`;
const deg = (v) => `${Math.round(v)}°`;

function renderLocList() {
  locList.innerHTML = locations.map((l, i) => {
    let label, cls = "cmp-chip";
    // Show the raw coordinates while pending/loading (with the loading class still
    // driving the spinner); once scored, l.name holds the resolved neighborhood +
    // city, so the coordinates are replaced live by the place name.
    const coords = `${l.lat.toFixed(2)}, ${l.lon.toFixed(2)}`;
    if (l.loading) { label = l.name || coords; cls += " loading"; }
    else if (l.error) { label = "Couldn't load"; cls += " error"; }
    else if (!l.series) { label = l.name || coords; cls += " pending"; }
    else { label = l.name; }
    return `<li class="${cls}"><span class="cmp-chip-name">${label}</span>` +
           `<button type="button" class="cmp-chip-x" data-i="${i}" aria-label="Remove ${label}">&times;</button></li>`;
  }).join("");
}

function rankCard(loc, s, rank) {
  const bar = `<div class="cmp-bar" role="img" aria-label="${pct(s.belowPct)} colder, ${pct(s.comfortPct)} in comfort, ${pct(s.abovePct)} warmer">` +
    `<span class="cmp-seg cmp-below" style="flex-basis:${s.belowPct}%"></span>` +
    `<span class="cmp-seg cmp-comfort" style="flex-basis:${s.comfortPct}%"></span>` +
    `<span class="cmp-seg cmp-above" style="flex-basis:${s.abovePct}%"></span></div>`;
  const stats =
    `<div class="cmp-stats">` +
      `<div class="cmp-stat cmp-s-below"><span class="cmp-k">Colder</span><span class="cmp-v">${pct(s.belowPct)}</span><span class="cmp-d">${s.below ? `avg ${deg(s.avgBelow)} below` : "—"}</span></div>` +
      `<div class="cmp-stat cmp-s-comfort"><span class="cmp-k">In comfort</span><span class="cmp-v">${pct(s.comfortPct)}</span><span class="cmp-d">±${tol}° of ${comfort}°</span></div>` +
      `<div class="cmp-stat cmp-s-above"><span class="cmp-k">Warmer</span><span class="cmp-v">${pct(s.abovePct)}</span><span class="cmp-d">${s.above ? `avg ${deg(s.avgAbove)} above` : "—"}</span></div>` +
    `</div>`;
  return `<div class="cmp-card">` +
    `<div class="cmp-card-top">` +
      `<span class="cmp-rank">#${rank}</span>` +
      `<div class="cmp-card-name"><span class="cmp-name">${loc.name}</span><span class="cmp-daycount">${s.n} days</span></div>` +
      `<div class="cmp-big"><b>${pct(s.comfortPct)}</b><span>in comfort</span></div>` +
    `</div>` +
    bar + stats +
    `<div class="cmp-mad">Typical day misses comfort by <b>${deg(s.mad)}</b></div>` +
  `</div>`;
}

function renderResults() {
  const loading = locations.filter((l) => l.loading).length;
  const scored = locations
    .map((l) => ({ loc: l, s: l.series ? computeStats(l.series) : null }))
    .filter((x) => x.s);
  // Best comfort share first; break ties by the smaller typical miss.
  scored.sort((a, b) => (b.s.comfortPct - a.s.comfortPct) || (a.s.mad - b.s.mad));

  if (!scored.length) {
    head.hidden = true;
    results.innerHTML = loading ? `<p class="spinner">Loading daily weather…</p>` : "";
    return;
  }

  // Headline: the winner + the parameters it was judged under.
  const win = scored[0];
  const span = `${monthLabel(range.start)} – ${monthLabel(range.end)}`;
  const lead = scored.length > 1
    ? `<b>${win.loc.name}</b> best matches ${comfort}° — ${pct(win.s.comfortPct)} of days within ±${tol}°`
    : `<b>${win.loc.name}</b>: ${pct(win.s.comfortPct)} of days within ±${tol}° of ${comfort}°`;
  head.hidden = false;
  head.innerHTML = `<h2>${lead}</h2>` +
    `<p class="meta">By ${BASIS_LABEL[basis]} · ${span}${loading ? ` · loading ${loading} more…` : ""}</p>`;

  results.innerHTML = scored.map((x, i) => rankCard(x.loc, x.s, i + 1)).join("");
}

function renderAll() {
  const has = locations.length > 0;
  params.hidden = !has;
  placeholder.hidden = has;
  addBtn.querySelector("span").textContent = has ? "Add another location" : "Add location";
  refreshBtn.hidden = !isDirty();
  renderLocList();
  renderResults();
}

// ---- events ----
addBtn.addEventListener("click", () => {
  const cur = locations.length ? locations[locations.length - 1] : window.Thermograph.loadLastLocation();
  window.LocationPicker.open(cur, (lat, lon) => addLocation(lat, lon));
});

refreshBtn.addEventListener("click", refresh);

locList.addEventListener("click", (e) => {
  const x = e.target.closest(".cmp-chip-x");
  if (x) removeLocation(+x.dataset.i);
});

// Comfort / band / basis: instant re-rank over data already in hand — no refetch.
comfortInput.addEventListener("input", () => {
  comfort = +comfortInput.value;
  comfortVal.textContent = `${comfort}°`;
  lsSet(CMP.comfort, String(comfort));
  writeHashState();
  renderResults();
});
tolInput.addEventListener("input", () => {
  tol = +tolInput.value;
  tolVal.textContent = `±${tol}°`;
  lsSet(CMP.tol, String(tol));
  writeHashState();
  renderResults();
});
basisToggle.addEventListener("click", (e) => {
  const btn = e.target.closest("button[data-basis]");
  if (!btn) return;
  basis = btn.dataset.basis;
  lsSet(CMP.basis, basis);
  basisToggle.querySelectorAll("button").forEach((b) => b.classList.toggle("active", b === btn));
  writeHashState();
  renderResults();
});

// Editing the dates doesn't load — it just arms Refresh (re-eval via renderAll).
startInput.max = endInput.max = `${new Date().getFullYear()}-12`;
startInput.addEventListener("change", renderAll);
endInput.addEventListener("change", renderAll);

// ---- init ----
(function restore() {
  const hash = readHashState();
  if (hash) {
    if (hash.comfort != null) comfort = hash.comfort;
    if (hash.tol != null) tol = hash.tol;
    if (hash.basis) basis = hash.basis;
    if (hash.start && hash.end) range = { start: hash.start, end: hash.end };
  }

  comfortInput.value = comfort; comfortVal.textContent = `${comfort}°`;
  tolInput.value = tol; tolVal.textContent = `±${tol}°`;
  basisToggle.querySelectorAll("button").forEach((b) => b.classList.toggle("active", b.dataset.basis === basis));
  startInput.value = range.start; endInput.value = range.end;

  // A shared link's locations win; else the last-used set; else seed from the spot
  // the other views were on so the page isn't empty. All three auto-load on arrival
  // (the tap-to-refresh rule is for later interactive edits, not the initial view).
  let list = hash && hash.locs;
  if (!list) { try { const saved = JSON.parse(lsGet(CMP.locs)); if (Array.isArray(saved)) list = saved; } catch (e) {} }
  if (!list || !list.length) { const last = window.Thermograph.loadLastLocation(); list = last ? [{ lat: last.lat, lon: last.lon }] : []; }

  locations = list
    .filter((l) => l && typeof l.lat === "number" && typeof l.lon === "number")
    .map((l) => ({ lat: l.lat, lon: l.lon, name: l.name || null, series: null, loading: false, error: null }));

  writeHashState();
  const token = ++loadToken;
  loadPending(token);
  renderAll();
})();