// ClawdDotNet — Token usage › Timeline (#660)
//
// Stacked bars per hour or day, grouped by agent, model or event, measuring cost, tokens or
// runs. Budget denials and model changes are drawn as markers on the axis - the usual
// explanation for a jump. Clicking a bar opens the runs of exactly that bucket and group.
//
// Inline SVG built with the DOM API: the manager runs offline, no chart library.

import { api } from "../modules/api.js";
import { erstelleElement, erstelleKarte, formatiereTokens, formatiereKosten } from "../modules/dom.js";
import { t } from "../modules/i18n.js";
import { readFilters, applyFilters, toApiQuery, loadFacets, buildFilterBar, rangeOf } from "../modules/usage-filters.js";
import { sourceLabel } from "./usage-runs.js";

const PATH = "/verbrauch/timeline";
const SVG = "http://www.w3.org/2000/svg";

// Distinguishable in light and dark theme; repeats after ten groups.
const PALETTE = ["#4e79a7", "#f28e2b", "#59a14f", "#e15759", "#76b7b2", "#edc948", "#b07aa1", "#ff9da7", "#9c755f", "#bab0ac"];

function svg(tag, attributes = {}, ...children) {
  const element = document.createElementNS(SVG, tag);
  for (const [key, value] of Object.entries(attributes)) element.setAttribute(key, String(value));
  for (const child of children) element.append(child);
  return element;
}

function title(text) {
  const element = document.createElementNS(SVG, "title");
  element.textContent = text;
  return element;
}

export async function renderUsageTimeline() {
  const container = document.getElementById("ansicht-inhalt");
  if (!container) return;

  const filters = readFilters();
  const bucket = filters.bucket ?? (["24h", "7d"].includes(filters.range) ? "hour" : "day");
  const groupBy = filters.groupBy ?? "agent";
  const metric = filters.metric ?? "cost";

  const layout = erstelleElement("div", { klasse: "verbrauch-ansicht" });
  layout.append(erstelleElement("h1", { text: t("timeline.title") }));

  const facets = await loadFacets(filters);
  layout.append(buildFilterBar(filters, facets, (next) => applyFilters(PATH, { ...next, bucket, groupBy, metric })));
  layout.append(buildControls(filters, bucket, groupBy, metric));

  const content = erstelleElement("div", {}, erstelleElement("div", { klasse: "hinweis-zentriert", text: t("common.loading") }));
  layout.append(content);
  container.replaceChildren(layout);

  let points;
  let events;
  try {
    const tzOffset = -new Date().getTimezoneOffset();
    [points, events] = await Promise.all([
      api(`/usage/series?${toApiQuery(filters, { bucket, groupBy, tzOffset })}`),
      api(`/usage/events?${toApiQuery(filters)}`)
    ]);
  } catch (err) {
    content.replaceChildren(erstelleKarte(t("runs.unavailable"), [erstelleElement("p", { klasse: "gedaempft", text: err.message })]));
    return;
  }

  if (points.length === 0) {
    content.replaceChildren(erstelleKarte(t("runs.empty.title"), [erstelleElement("p", { klasse: "gedaempft", text: t("runs.empty.text") })]));
    return;
  }

  content.replaceChildren(buildChart(points, events, filters, bucket, groupBy, metric));
}

function buildControls(filters, bucket, groupBy, metric) {
  const bar = erstelleElement("div", { klasse: "reiter-leiste diagramm-steuerung" });

  const group = (name, options, current) => {
    const wrapper = erstelleElement("div", { klasse: "gruppe-horizontal" },
      erstelleElement("span", { klasse: "gedaempft klein", text: t(`timeline.${name}`) }));
    for (const option of options) {
      wrapper.append(erstelleElement("button", {
        type: "button",
        klasse: `reiter-schaltflaeche${option === current ? " aktiv" : ""}`,
        text: t(`timeline.${name}.${option}`),
        onclick: () => applyFilters(PATH, { ...readFilters(), bucket, groupBy, metric, [name]: option })
      }));
    }
    return wrapper;
  };

  bar.append(
    group("metric", ["cost", "tokens", "runs"], metric),
    group("groupBy", ["agent", "model", "source"], groupBy),
    group("bucket", ["hour", "day"], bucket));
  return bar;
}

function bucketsBetween(from, to, bucket) {
  const step = bucket === "day" ? 864e5 : 36e5;
  const start = new Date(from);
  if (bucket === "day") start.setHours(0, 0, 0, 0);
  else start.setMinutes(0, 0, 0);
  const list = [];
  for (let time = start.getTime(); time < new Date(to).getTime() && list.length < 2000; time += step) {
    list.push(time);
  }
  return list;
}

function formatBucket(time, bucket) {
  const date = new Date(time);
  return bucket === "day"
    ? date.toLocaleDateString(undefined, { day: "2-digit", month: "2-digit" })
    : date.toLocaleString(undefined, { day: "2-digit", month: "2-digit", hour: "2-digit", minute: "2-digit" });
}

function formatValue(value, metric) {
  return metric === "cost" ? formatiereKosten(value) : metric === "tokens" ? formatiereTokens(value) : String(value);
}

function buildChart(points, events, filters, bucket, groupBy, metric) {
  const valueOf = (p) => (metric === "cost" ? Number(p.costUsd) : metric === "tokens" ? p.tokens : p.runs);
  const { from, to } = rangeOf(filters);

  // The API only returns buckets that have runs; the axis shows the whole range.
  const firstPoint = Math.min(...points.map((p) => new Date(p.bucketStart).getTime()));
  const buckets = bucketsBetween(Math.min(new Date(from).getTime(), firstPoint), to, bucket);
  const step = bucket === "day" ? 864e5 : 36e5;
  const indexOf = (time) => Math.floor((time - buckets[0]) / step);

  const groups = [...new Set(points.map((p) => p.group))].sort();
  const color = (group) => PALETTE[groups.indexOf(group) % PALETTE.length];

  const stacks = buckets.map(() => []);
  for (const p of points) {
    const i = indexOf(new Date(p.bucketStart).getTime());
    if (i >= 0 && i < stacks.length) stacks[i].push(p);
  }
  const max = Math.max(...stacks.map((s) => s.reduce((sum, p) => sum + valueOf(p), 0)), 0) || 1;

  const barWidth = Math.max(4, Math.min(28, Math.floor(1100 / buckets.length)));
  const left = 70;
  const top = 16;
  const height = 260;
  const width = left + buckets.length * barWidth + 20;
  const chart = svg("svg", {
    class: "zeitverlauf",
    viewBox: `0 0 ${width} ${height + top + 50}`,
    width,
    height: height + top + 50,
    role: "img",
    "aria-label": t("timeline.title")
  });

  // Axis and grid: four lines with the value.
  for (let i = 0; i <= 4; i++) {
    const y = top + height - (height * i) / 4;
    chart.append(svg("line", { x1: left, x2: width - 10, y1: y, y2: y, class: "raster" }));
    const label = svg("text", { x: left - 6, y: y + 4, "text-anchor": "end", class: "achse" });
    label.textContent = formatValue((max * i) / 4, metric);
    chart.append(label);
  }

  const labelEvery = Math.ceil(buckets.length / 12);
  stacks.forEach((stack, i) => {
    const x = left + i * barWidth;
    let y = top + height;
    for (const p of stack) {
      const h = (valueOf(p) / max) * height;
      if (h <= 0) continue;
      y -= h;
      const rect = svg("rect", {
        x: x + 1, y, width: barWidth - 2, height: h, fill: color(p.group), class: "balken", tabindex: 0
      }, title(`${formatBucket(buckets[i], bucket)} · ${groupBy === "source" ? sourceLabel(p.group) : p.group}: ` +
        `${formatValue(valueOf(p), metric)} (${t("timeline.tooltipRuns", { n: p.runs })})`));
      rect.addEventListener("click", () => openBucket(filters, buckets[i], step, groupBy, p.group));
      chart.append(rect);
    }
    if (i % labelEvery === 0) {
      const label = svg("text", { x: x + barWidth / 2, y: top + height + 16, "text-anchor": "middle", class: "achse" });
      label.textContent = formatBucket(buckets[i], bucket);
      chart.append(label);
    }
  });

  for (const event of events) {
    const time = new Date(event.at).getTime();
    const i = (time - buckets[0]) / step;
    if (i < 0 || i > buckets.length) continue;
    const x = left + i * barWidth;
    const kind = event.kind === "budget_exceeded" ? "ereignis-budget" : "ereignis-modell";
    chart.append(svg("g", { class: `ereignis ${kind}` },
      svg("line", { x1: x, x2: x, y1: top, y2: top + height }),
      svg("path", { d: `M${x - 5},${top + height + 22} L${x + 5},${top + height + 22} L${x},${top + height + 30} Z` }),
      title(`${new Date(event.at).toLocaleString()} · ${event.agentId}: ${t(`timeline.event.${event.kind}`)} – ${event.text}`)));
  }

  const legend = erstelleElement("div", { klasse: "legende" });
  for (const group of groups) {
    const total = points.filter((p) => p.group === group).reduce((sum, p) => sum + valueOf(p), 0);
    legend.append(erstelleElement("span", { klasse: "legende-eintrag" },
      erstelleElement("span", { klasse: "legende-farbe", stil: { background: color(group) } }),
      erstelleElement("span", { text: `${groupBy === "source" ? sourceLabel(group) : group}: ${formatValue(total, metric)}` })));
  }
  if (events.length > 0) {
    legend.append(
      erstelleElement("span", { klasse: "legende-eintrag" },
        erstelleElement("span", { klasse: "legende-marke ereignis-budget" }),
        erstelleElement("span", { text: t("timeline.event.budget_exceeded") })),
      erstelleElement("span", { klasse: "legende-eintrag" },
        erstelleElement("span", { klasse: "legende-marke ereignis-modell" }),
        erstelleElement("span", { text: t("timeline.event.model_changed") })));
  }

  return erstelleKarte(t("timeline.chart"), [
    erstelleElement("div", { klasse: "diagramm-scroll" }, chart),
    legend,
    erstelleElement("p", { klasse: "hinweis", text: t("timeline.hint") })
  ]);
}

function openBucket(filters, start, step, groupBy, group) {
  const day = (time) => {
    const d = new Date(time);
    return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, "0")}-${String(d.getDate()).padStart(2, "0")}`;
  };
  const next = { ...filters, range: "custom", from: day(start), to: day(start + step - 1), offset: 0 };
  delete next.bucket;
  delete next.groupBy;
  delete next.metric;
  next[groupBy === "source" ? "source" : groupBy] = group;
  applyFilters("/verbrauch/runs", next);
}