'use strict';

/**
 * The causally-correct defence atom.
 *
 * The bug these guard against is subtle and total: getting handedness backwards
 * sends half the league's grounders to the wrong infielders, and the atom still
 * LOOKS like it is reading defence. Nothing downstream would catch it.
 */

const sd = require('../../src/services/model/sprayDefense');

const pullGround = {
  pull_gb: 0.45, straight_gb: 0.10, oppo_gb: 0.05,
  pull_air: 0.20, straight_air: 0.12, oppo_air: 0.08,
};
const pos = (o) => Object.fromEntries(Object.entries(o).map(([k, v]) => [k, { oaa: v, fielders: 2 }]));

describe('handedness maps pull to the RIGHT side of the field', () => {
  it('a RIGHT-handed pull hitter meets 3B/SS', () => {
    // Elite left side, terrible right side.
    const d = pos({ '3B': 12, SS: 10, '1B': -10, '2B': -10, LF: 0, CF: 0, RF: 0 });
    const r = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: d });
    expect(r.multiplier).toBeLessThan(1);           // suppressed
    expect(r.contributions.find((c) => c.cell === 'pull_gb').positions).toEqual(['3B', 'SS']);
  });

  it('the SAME hitter batting LEFT meets 1B/2B — the mirror image', () => {
    const d = pos({ '3B': 12, SS: 10, '1B': -10, '2B': -10, LF: 0, CF: 0, RF: 0 });
    const right = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: d });
    const left = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'L', positionOaa: d });
    // Against the same defence, pulling into the good side vs the bad side must
    // move the read in OPPOSITE directions. Getting this backwards would be
    // invisible downstream.
    expect(right.multiplier).toBeLessThan(1);
    expect(left.multiplier).toBeGreaterThan(1);
  });

  it('a SWITCH hitter is unreadable, not guessed', () => {
    const d = pos({ '3B': 5, SS: 5, '1B': 5, '2B': 5 });
    expect(sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'S', positionOaa: d })).toBeNull();
  });
});

describe('this is what team-average could not express', () => {
  it('two teams with the SAME total defence read differently for a pull hitter', () => {
    // Both sum to +4 — indistinguishable to the team-average factor.
    const leftStrong = pos({ '3B': 12, SS: 8, '1B': -8, '2B': -8, LF: 0, CF: 0, RF: 0 });
    const rightStrong = pos({ '3B': -8, SS: -8, '1B': 12, '2B': 8, LF: 0, CF: 0, RF: 0 });
    const a = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: leftStrong });
    const b = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: rightStrong });
    expect(a.multiplier).toBeLessThan(b.multiplier);
    // The whole reason the crude version failed the gate.
  });

  it('a ground-ball hitter and an air hitter read the SAME team differently', () => {
    const badInfieldGoodOutfield = pos({ '3B': -10, SS: -10, '1B': -8, '2B': -8, LF: 10, CF: 10, RF: 10 });
    const grounder = { pull_gb: 0.5, straight_gb: 0.3, oppo_gb: 0.2, pull_air: 0, straight_air: 0, oppo_air: 0 };
    const flyer = { pull_gb: 0, straight_gb: 0, oppo_gb: 0, pull_air: 0.5, straight_air: 0.3, oppo_air: 0.2 };
    const g = sd.sprayDefenseMultiplier({ spray: grounder, bats: 'R', positionOaa: badInfieldGoodOutfield });
    const f = sd.sprayDefenseMultiplier({ spray: flyer, bats: 'R', positionOaa: badInfieldGoodOutfield });
    expect(g.multiplier).toBeGreaterThan(1);   // his grounders find holes
    expect(f.multiplier).toBeLessThan(1);      // his fly balls get run down
  });
});

describe('honesty — absent zones contribute nothing, not zero', () => {
  it('an unmeasured position is renormalised away, never treated as average', () => {
    const partial = { '3B': 12, SS: 12 };      // only the pull-ground zone known
    const r = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: pos(partial) });
    expect(r).not.toBeNull();
    // Coverage states honestly how much of his contact we could actually read.
    expect(r.coverage).toBeCloseTo(0.45 + 0.10, 2);   // pull_gb + straight_gb(SS)
    expect(r.multiplier).toBeLessThan(1);
  });

  it('nothing readable at all → null, never a 1.0 that looks measured', () => {
    expect(sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: {} })).toBeNull();
    expect(sd.sprayDefenseMultiplier({ spray: null, bats: 'R', positionOaa: pos({ '3B': 5 }) })).toBeNull();
    expect(sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: null })).toBeNull();
  });

  it('the effect is bounded — no stack of positions runs away', () => {
    const absurd = pos({ '3B': 500, SS: 500, '1B': 500, '2B': 500, LF: 500, CF: 500, RF: 500 });
    const r = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: absurd });
    expect(r.multiplier).toBeGreaterThanOrEqual(1 - sd.MAX_EFFECT - 1e-9);
  });

  it('a league-average defence leaves the read untouched', () => {
    const r = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: pos({ '3B': 0, SS: 0, '1B': 0, '2B': 0, LF: 0, CF: 0, RF: 0 }) });
    expect(r.multiplier).toBeCloseTo(1, 6);
  });
});

describe('the reasoning shown to a user is checkable, or absent', () => {
  it('names the zone and the direction', () => {
    const d = pos({ '3B': 12, SS: 10, '1B': 0, '2B': 0, LF: 0, CF: 0, RF: 0 });
    const r = sd.sprayDefenseMultiplier({ spray: pullGround, bats: 'R', positionOaa: d });
    const text = sd.explain(r, 'Chicago Cubs');
    expect(text).toMatch(/pull gb/);
    expect(text).toMatch(/Chicago Cubs is strong/);
  });

  it('NO read means NO sentence — never a fluent fallback', () => {
    expect(sd.explain(null, 'Cubs')).toBeNull();
  });
});