// Shared by the stats overview and the per-alert drilldown: the time-range
// chips, the chart cards and the SVG column chart.

import { h } from './ui.js';

const DAY_MS = 24 * 60 * 60 * 1000;

// `days` counts back from today, inclusive; the server reads from/to as UTC
// dates, so these are too.
export const RANGES = [
  { id: 'today', label: 'Today', days: 1 },
  { id: '7d', label: '7d', days: 7 },
  { id: '30d', label: '30d', days: 30 },
  { id: '90d', label: '90d', days: 90 },
  { id: 'all', label: 'All', days: null },
];

// The chosen range outlives navigating between the overview and a drilldown.
let range = '30d';
export const getRange = () => range;
export const setRangeId = (id) => { range = id; };

const utcDate = (ms) => new Date(ms).toISOString().slice(0, 10);

export function rangeQuery() {
  const r = RANGES.find((x) => x.id === range);
  if (!r.days) return {};
  const now = Date.now();
  return { from: utcDate(now - (r.days - 1) * DAY_MS), to: utcDate(now) };
}

export function chips(onPick, ranges = RANGES) {
  return h('div', { class: 'chips', role: 'tablist', 'aria-label': 'Time range' },
    ranges.map((r) => h('button', {
      class: 'chip',
      type: 'button',
      role: 'tab',
      'aria-selected': String(r.id === range),
      onclick: () => onPick(r.id),
      text: r.label,
    })));
}

export function card(title, content, note) {
  return h('section', { class: 'chart-card card card-pad' },
    h('div', { class: 'chart-head' },
      h('h3', { class: 'chart-title', text: title }),
      note && h('span', { class: 'chart-note', text: note })),
    content);
}

export const pad2 = (n) => String(n).padStart(2, '0');
export const WEEKDAYS = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
// Monday first, as the mockup has it; server weekdays are 0=Sunday.
export const MONDAY_FIRST = [1, 2, 3, 4, 5, 6, 0];

const SVG_NS = 'http://www.w3.org/2000/svg';

function svg(tag, attrs = {}, text) {
  const el = document.createElementNS(SVG_NS, tag);
  for (const [k, v] of Object.entries(attrs)) el.setAttribute(k, String(v));
  if (text != null) el.textContent = text;
  return el;
}

// A column chart: one bar per item, the value in a tooltip, and a label under
// the items marked `tick`.
export function columns(items, label) {
  const W = 480;
  const H = 140;
  const base = H - 18;
  const step = W / items.length;
  const max = Math.max(...items.map((x) => x.value), 1);
  const root = svg('svg', {
    class: 'columns', viewBox: `0 0 ${W} ${H}`, role: 'img', 'aria-label': label,
  });
  root.appendChild(svg('line', { class: 'axis', x1: 0, x2: W, y1: base, y2: base }));
  items.forEach((it, i) => {
    const bh = it.value ? Math.max(2, (it.value / max) * (base - 6)) : 0;
    const x = i * step + step * 0.15;
    const g = svg('g', { class: 'col' });
    g.appendChild(svg('title', {}, `${it.label}: ${it.value}`));
    // A full-height transparent hit area, so a tiny bar is still hoverable.
    g.appendChild(svg('rect', { class: 'col-hit', x: i * step, y: 0, width: step, height: base }));
    if (bh) g.appendChild(svg('rect', { class: 'col-bar', x, y: base - bh, width: step * 0.7, height: bh, rx: 2 }));
    root.appendChild(g);
    if (it.tick) {
      root.appendChild(svg('text', { class: 'col-label', x: i * step + step / 2, y: H - 4, 'text-anchor': 'middle' }, it.label));
    }
  });
  return root;
}

// A 7×24 weekday-by-hour grid from `grid[weekday][hour]` (0=Sunday); cell
// opacity steps with the count relative to the busiest cell.
export function heatmap(grid) {
  const max = Math.max(...grid.flat(), 1);
  const level = (c) => (c === 0 ? 0 : Math.min(4, Math.ceil((c / max) * 4)));
  const rows = MONDAY_FIRST.map((w) => h('div', { class: 'heat-row' },
    h('span', { class: 'heat-day', text: WEEKDAYS[w] }),
    h('div', { class: 'heat-cells' }, grid[w].map((c, hr) => h('div', {
      class: `heat-cell lv${level(c)}`,
      title: `${WEEKDAYS[w]} ${pad2(hr)}:00 UTC: ${c}`,
    })))));
  const axis = h('div', { class: 'heat-row' },
    h('span', { class: 'heat-day' }),
    h('div', { class: 'heat-cells' }, Array.from({ length: 24 }, (_, hr) =>
      h('span', { class: 'heat-hour', text: hr % 3 === 0 ? pad2(hr) : '' }))));
  const peak = grid.flatMap((row, d) => row.map((c, hr) => ({ d, hr, c }))).reduce((a, b) => (b.c > a.c ? b : a));
  return h('div', {
    class: 'heatmap',
    role: 'img',
    'aria-label': peak.c
      ? `Heatmap of incidents by weekday and hour in UTC. The busiest slot is ${WEEKDAYS[peak.d]} at ${pad2(peak.hr)}:00 with ${peak.c}.`
      : 'Heatmap of incidents by weekday and hour in UTC. Nothing in this range.',
  }, rows, axis);
}