// The fit through the Food (grams) bars. The arithmetic is easy to get subtly
// wrong and the result is a sentence stating a fact about the puppy, so the
// cases that matter are the ones where it should decline to say anything.
import { load } from "./extract.mjs";
import { suite, eq, ok, report } from "./assert.mjs";

const app = load({ names: ["foodTrend"] });
const words = load({ names: ["foodTrendSentence"] });

// The 7/14/30 picker reaches the trend by deciding how many days weeklyData
// builds — there is no second mechanism, so this is the thing to hold still.
let windowDays = 7;
const weekly = load({
  names: ["startOfDay", "endOfDay", "ymd", "weeklyData"],
  stubs: {
    chartDays: () => windowDays,
    isExcluded: () => false,
    eventsForDay: () => [],
    sleepMsInRange: () => 0,
    walkMsInRange: () => 0,
  },
});

suite("the day picker is what sets the trend's window");
for (const n of [7, 14, 30]) {
  windowDays = n;
  eq(weekly.weeklyData([]).length, n, `picking ${n}d gives the charts ${n} days to fit over`);
}
windowDays = 7;

// weeklyData's shape, as far as foodTrend reads it. Today is last, as there.
const days = (grams, { excluded = [] } = {}) =>
  grams.map((g, i) => ({ grams: g, excluded: excluded.includes(i) }));

suite("it declines to fit when there is nothing to fit");
{
  eq(app.foodTrend(days([300, 320, 310])), null,
     "three days is too few — today is dropped, leaving two, and two always fit perfectly");
  eq(app.foodTrend(days([300, 320, 310, 330, 340], { excluded: [0, 1] })), null,
     "marked days don't count toward the four either");
  eq(app.foodTrend(days([])), null, "an empty window fits nothing");
}

suite("today is left out, being half-eaten");
{
  // Four steady days then a partial today. Including today would tip the line
  // down; the fit should not see it at all.
  const t = app.foodTrend(days([400, 400, 400, 400, 50]));
  ok(t, "four complete days are enough");
  eq(Math.round(t.perWeek), 0, "a flat run stays flat despite today being low");
  eq(t.last, 3, "the line stops at the last complete day, not at today");
}

suite("it reports a direction only when the climb beats the scatter");
{
  const rising = app.foodTrend(days([200, 250, 300, 350, 400, 450, 0]));
  ok(rising.clear, "a clean climb is reported");
  eq(Math.round(rising.perWeek), 350, "…at 50 g a day, which is 350 g a week");

  const falling = app.foodTrend(days([450, 400, 350, 300, 250, 200, 0]));
  ok(falling.clear, "a clean fall is reported");
  ok(falling.perWeek < 0, "…with a negative weekly change");

  // Same mean, no direction, plenty of noise: the honest answer is "steady".
  const noisy = app.foodTrend(days([200, 500, 210, 480, 190, 520, 0]));
  ok(!noisy.clear, "a see-saw is not a trend, however the slope comes out");

  // A gentle real climb buried in large day-to-day swings: also not claimable.
  const buried = app.foodTrend(days([300, 520, 180, 540, 200, 560, 0]));
  ok(!buried.clear, "a slope smaller than the scatter is not reported as a trend");
}

suite("the fitted line passes through the data");
{
  const t = app.foodTrend(days([100, 200, 300, 400, 500, 0]));
  eq(Math.round(t.at(0)), 100, "it starts where the first day sits");
  eq(Math.round(t.at(4)), 500, "and ends where the last complete day sits");
  eq(Math.round(t.mean), 300, "the mean is the mean of the days it fitted");
}

suite("marked days are skipped without shifting the line");
{
  // The middle day is marked; the rest describe a clean 50 g/day climb. The fit
  // must ignore the hatch rather than reading it as a day of zero grams.
  const t = app.foodTrend(days([200, 250, 0, 350, 400, 450, 0], { excluded: [2] }));
  eq(Math.round(t.perWeek), 350, "the climb is unchanged by the marked day");
  ok(t.clear, "…and it is still clear, not drowned by a false zero");
}

suite("what the sentence is allowed to say");
{
  const say = (grams, opts) => words.foodTrendSentence(app.foodTrend(days(grams, opts)), 14);

  const rising = say([200, 250, 300, 350, 400, 450, 0]);
  ok(/up about 350 g a week/.test(rising), "a clear climb gives the rate");
  ok(/200 g a day then/.test(rising) && /450 g a day now/.test(rising),
     "…and the figures at each end of the line, so it is not only a rate");
  ok(/the last 14 days/.test(rising), "…named against the window it was fitted over");

  const steady = say([300, 302, 298, 301, 299, 300, 0]);
  ok(/roughly steady/.test(steady), "a flat run is called steady");
  ok(/averaging about 300 g a day/.test(steady),
     "…and quotes the average, which is a measurement rather than model output");
  ok(!/then/.test(steady) && !/ now\b/.test(steady),
     "…but not fitted endpoints, which would dress up a line nobody should read");

  const noisy = say([200, 500, 210, 480, 190, 520, 0]);
  ok(/roughly steady/.test(noisy) && /variation is larger/.test(noisy),
     "a see-saw says the variation beat the trend, rather than quoting a slope");

  const none = say([300, 320, 310]);
  ok(/Not enough complete days/.test(none) && /needs four/.test(none),
     "too few days explains itself instead of leaving the chart bare");

  // False precision would make a fit look like a reading.
  ok(/\b\d*[05] g a day/.test(rising), "figures are rounded to 10 g, not quoted to the gram");
  const falling = say([450, 400, 350, 300, 250, 200, 0]);
  ok(/down about/.test(falling), "a clear fall says down");
}

export default report("food-trend");