// Headless guard for the trace-chart viewer (chart-viewer.js). Property protected:
// buildCharts maps an AURA_TRACES payload to uPlot configs WITHOUT a DOM — overlay
// is one chart with every series on its own y-scale over the shared xs; panels is
// one chart per series, each on the SAME shared xs (timestamp-aligned). It loads the
// real viewer module (a fix/regression there is observed here) and drives the
// exported pure `buildCharts`; uPlot itself (which needs `document`) is never
// instantiated — mount() is browser-only and not called here.

import { createRequire } from "node:module";
import { readFileSync } from "node:fs";
import { fileURLToPath } from "node:url";
import { dirname, join } from "node:path";

const require = createRequire(import.meta.url);
const here = dirname(fileURLToPath(import.meta.url));
const traces = JSON.parse(readFileSync(join(here, "fixtures", "sample-traces.json"), "utf8"));

const fail = (msg) => { console.error("FAIL: " + msg); process.exit(1); };
const eq = (a, b, msg) => { if (a !== b) fail(`${msg} (got ${a}, want ${b})`); };
const sameArr = (a, b, msg) => {
  if (!Array.isArray(a) || !Array.isArray(b) || a.length !== b.length || a.some((v, i) => v !== b[i])) fail(msg);
};

// No `document` global -> chart-viewer.js's browser mount is skipped; require gives
// us only the pure export (mirrors viewer_dot_ids.mjs stubbing window before require).
global.window = { AURA_TRACES: traces };
const { buildCharts } = require(join(here, "..", "assets", "chart-viewer.js"));

const n = traces.series.length;
const idx = Array.from({ length: traces.xs.length }, (_, i) => i);

// overlay: ONE chart, all series superimposed, each on its own scale. Default x spine is
// ORDINAL (indices) so non-trading gaps collapse.
const overlay = buildCharts(traces, "overlay");
eq(overlay.length, 1, "overlay is one chart");
eq(overlay[0].data.length, 1 + n, "overlay data = xs + N series");
eq(overlay[0].opts.series.length, 1 + n, "overlay uPlot series = x + N");
sameArr(overlay[0].data[0], idx, "default overlay x-axis is the ordinal index spine");
const scaleIds = overlay[0].opts.series.slice(1).map((s) => s.scale);
eq(new Set(scaleIds).size, n, "each overlay series has a distinct y-scale");

// continuous mode restores the real-timestamp x spine.
const overlayC = buildCharts(traces, "overlay", "continuous");
sameArr(overlayC[0].data[0], traces.xs, "continuous overlay x-axis is the shared xs");

// panels: ONE chart per series, all positionally aligned on the SAME ordinal spine.
const panels = buildCharts(traces, "panels");
eq(panels.length, n, "panels = one chart per series");
for (const p of panels) {
  eq(p.data.length, 2, "each panel = xs + its one series");
  sameArr(p.data[0], idx, "panel shares the same ordinal index spine (position-aligned)");
}

console.log(`OK — overlay 1 chart / ${n} series, panels ${n} charts, shared xs.`);
process.exit(0);