Evening Star

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export type JsonObject = Record<string, any>;

const TITLES: Record<string, string> = {
  "D06-F04-A01": "Morning Star",
  "D06-F04-A02": "Evening Star",
  "D06-F04-A03": "Three White Soldiers",
  "D06-F04-A04": "Three Black Crows",
  "D06-F04-A05": "Three Inside Up/Down",
  "D06-F04-A06": "Three Outside Up/Down",
  "D06-F04-A07": "Abandoned Baby",
};

function finite(value: unknown, name: string): number {
  if (typeof value !== "number" || !Number.isFinite(value)) throw new TypeError(`${name} must be a finite number`);
  return value;
}

function positive(value: unknown, name: string): number {
  const result = finite(value, name);
  if (result <= 0) throw new RangeError(`${name} must be positive`);
  return result;
}

function fraction(value: unknown, name: string): number {
  const result = finite(value, name);
  if (result < 0 || result > 1) throw new RangeError(`${name} must be between 0 and 1`);
  return result;
}

function numbers(value: unknown, name: string): number[] {
  if (!Array.isArray(value)) throw new TypeError(`${name} must be an array`);
  const result = value.map((item, index) => finite(item, `${name}[${index}]`));
  if (result.some(item => item < 0)) throw new RangeError(`${name} cannot contain negative values`);
  return result;
}

function candle(value: unknown, name: string): JsonObject {
  if (value === null || typeof value !== "object" || Array.isArray(value)) throw new TypeError(`${name} must be an object`);
  const raw = value as JsonObject;
  const result = {open: finite(raw.open, `${name}.open`), high: finite(raw.high, `${name}.high`), low: finite(raw.low, `${name}.low`), close: finite(raw.close, `${name}.close`)};
  if (result.high < Math.max(result.open, result.close, result.low)) throw new RangeError(`${name}.high is below another OHLC value`);
  if (result.low > Math.min(result.open, result.close, result.high)) throw new RangeError(`${name}.low is above another OHLC value`);
  return result;
}

function anatomy(raw: JsonObject): JsonObject {
  const bodyHigh = Math.max(raw.open, raw.close), bodyLow = Math.min(raw.open, raw.close), body = bodyHigh - bodyLow;
  const direction = raw.close > raw.open ? "bullish" : raw.close < raw.open ? "bearish" : "neutral";
  return {...raw, body_high: bodyHigh, body_low: bodyLow, body, upper_shadow: raw.high - bodyHigh, lower_shadow: bodyLow - raw.low, range: raw.high - raw.low, direction};
}

function median(values: number[]): number {
  const ordered = [...values].sort((a, b) => a - b), middle = Math.floor(ordered.length / 2);
  return ordered.length % 2 ? ordered[middle] : (ordered[middle - 1] + ordered[middle]) / 2;
}

function base(data: JsonObject): JsonObject {
  if (!Array.isArray(data.candles) || data.candles.length !== 3) throw new RangeError("candles must contain exactly three OHLC candles");
  const candles = data.candles.map((item: unknown, index: number) => anatomy(candle(item, `candles[${index}]`)));
  const tick = positive(data.tick_size, "tick_size");
  const context = data.trend_context;
  if (!new Set(["uptrend", "downtrend", "sideways"]).has(context)) throw new RangeError("trend_context must be uptrend, downtrend, or sideways");
  const bodies = numbers(data.prior_bodies, "prior_bodies"), ranges = numbers(data.prior_ranges, "prior_ranges");
  if (bodies.length !== ranges.length) throw new RangeError("prior_bodies and prior_ranges must have equal length");
  if (bodies.some((body, index) => body > ranges[index])) throw new RangeError("a prior body cannot exceed its range");
  const count = bodies.length;
  return {candles, tick, context, bodyScale: count >= 5 ? median(bodies.slice(-10)) : null, rangeScale: count >= 5 ? median(ranges.slice(-10)) : null, count, penetration: fraction(data.penetration_fraction ?? 0.5, "penetration_fraction")};
}

function result(topicId: string, candles: JsonObject[], context: string, requiredContext: string | null, bodyScale: number | null, rangeScale: number | null, historyCount: number, direction: string, inputChecks: Record<string, boolean>, thresholds: JsonObject): JsonObject {
  let checks = inputChecks, state: string, matched: boolean;
  if (bodyScale === null || rangeScale === null) { checks = {minimum_history: false}; state = "warmup"; matched = false; }
  else {
    const geometry = Object.values(checks).every(Boolean);
    if (geometry && requiredContext !== null && context !== requiredContext) { state = "wrong-context"; matched = false; }
    else { matched = geometry; state = matched ? "matched" : "not-matched"; }
  }
  const failed = Object.entries(checks).filter(([, passed]) => !passed).map(([name]) => name);
  const score = Object.values(checks).filter(Boolean).length / Math.max(1, Object.keys(checks).length);
  const reason = failed.length ? `failed ${failed[0].replaceAll("_", " ")}` : "all declared checks pass";
  return {topic_id: topicId, pattern: TITLES[topicId], matched, state, direction, trend_context: context, required_context: requiredContext, history_count: historyCount, body_scale: bodyScale, range_scale: rangeScale, geometry_score: score, checks, failed_checks: failed, reason, thresholds, candles};
}

function star(topicId: string, data: JsonObject): JsonObject {
  const b = base(data), [a, middle, c] = b.candles, bullish = topicId === "D06-F04-A01", required = bullish ? "downtrend" : "uptrend";
  if (b.bodyScale === null || b.rangeScale === null) return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, bullish ? "bullish" : "bearish", {}, {});
  const longFloor = 1.2 * b.bodyScale, shortCeiling = 0.6 * b.bodyScale;
  let penetrationPrice: number, checks: Record<string, boolean>;
  if (bullish) {
    penetrationPrice = a.close + b.penetration * a.body;
    checks = {first_bearish: a.direction === "bearish", first_long: a.body >= longFloor, second_short: middle.body <= shortCeiling, body_gap_down: middle.body_high <= a.body_low - b.tick, third_bullish: c.direction === "bullish", third_penetrates: c.close >= penetrationPrice};
  } else {
    penetrationPrice = a.close - b.penetration * a.body;
    checks = {first_bullish: a.direction === "bullish", first_long: a.body >= longFloor, second_short: middle.body <= shortCeiling, body_gap_up: middle.body_low >= a.body_high + b.tick, third_bearish: c.direction === "bearish", third_penetrates: c.close <= penetrationPrice};
  }
  return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, bullish ? "bullish" : "bearish", checks, {long_body_floor: longFloor, short_body_ceiling: shortCeiling, penetration_price: penetrationPrice, minimum_gap: b.tick, penetration_fraction: b.penetration});
}

function soldiersOrCrows(topicId: string, data: JsonObject): JsonObject {
  const b = base(data), [a, middle, c] = b.candles, bullish = topicId === "D06-F04-A03", required = bullish ? "downtrend" : "uptrend";
  if (b.bodyScale === null || b.rangeScale === null) return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, bullish ? "bullish" : "bearish", {}, {});
  const bodyFloor = 0.75 * b.bodyScale, shadowCeiling = 0.2 * b.rangeScale;
  const checks: Record<string, boolean> = bullish ? {
    three_bullish: b.candles.every((item: JsonObject) => item.direction === "bullish"), material_bodies: b.candles.every((item: JsonObject) => item.body >= bodyFloor), rising_closes: middle.close >= a.close + b.tick && c.close >= middle.close + b.tick, second_opens_in_prior_body: a.body_low <= middle.open && middle.open <= a.body_high, third_opens_in_prior_body: middle.body_low <= c.open && c.open <= middle.body_high, short_upper_shadows: b.candles.every((item: JsonObject) => item.upper_shadow <= shadowCeiling)
  } : {
    three_bearish: b.candles.every((item: JsonObject) => item.direction === "bearish"), material_bodies: b.candles.every((item: JsonObject) => item.body >= bodyFloor), falling_closes: middle.close <= a.close - b.tick && c.close <= middle.close - b.tick, second_opens_in_prior_body: a.body_low <= middle.open && middle.open <= a.body_high, third_opens_in_prior_body: middle.body_low <= c.open && c.open <= middle.body_high, short_lower_shadows: b.candles.every((item: JsonObject) => item.lower_shadow <= shadowCeiling)
  };
  return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, bullish ? "bullish" : "bearish", checks, {body_floor: bodyFloor, shadow_ceiling: shadowCeiling, minimum_close_step: b.tick});
}

function inside(data: JsonObject): JsonObject {
  const topicId = "D06-F04-A05", b = base(data), [a, middle, c] = b.candles;
  const bullish = a.direction === "bearish" && middle.direction === "bullish", bearish = a.direction === "bullish" && middle.direction === "bearish";
  const direction = bullish ? "bullish" : bearish ? "bearish" : "none", required = bullish ? "downtrend" : bearish ? "uptrend" : null;
  if (b.bodyScale === null || b.rangeScale === null) return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, direction, {}, {});
  const longFloor = 1.2 * b.bodyScale, shortCeiling = 0.6 * b.bodyScale;
  const contained = middle.body_low >= a.body_low && middle.body_high <= a.body_high && (middle.body_low > a.body_low || middle.body_high < a.body_high);
  const confirms = (bullish && c.direction === "bullish" && c.close >= a.open + b.tick) || (bearish && c.direction === "bearish" && c.close <= a.open - b.tick);
  return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, direction, {opposite_first_pair: bullish || bearish, first_long: a.body >= longFloor, second_short: middle.body <= shortCeiling, second_body_inside: contained, third_confirms_past_first_open: confirms}, {long_body_floor: longFloor, short_body_ceiling: shortCeiling, confirmation_step: b.tick});
}

function outside(data: JsonObject): JsonObject {
  const topicId = "D06-F04-A06", b = base(data), [a, middle, c] = b.candles;
  const bullish = a.direction === "bearish" && middle.direction === "bullish", bearish = a.direction === "bullish" && middle.direction === "bearish";
  const direction = bullish ? "bullish" : bearish ? "bearish" : "none", required = bullish ? "downtrend" : bearish ? "uptrend" : null;
  const engulfed = middle.body_low <= a.body_low && middle.body_high >= a.body_high && middle.body > a.body;
  const confirms = (bullish && c.direction === "bullish" && c.close >= middle.close + b.tick) || (bearish && c.direction === "bearish" && c.close <= middle.close - b.tick);
  return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, direction, {opposite_first_pair: bullish || bearish, second_body_engulfs: engulfed, third_confirms_beyond_second_close: confirms}, {confirmation_step: b.tick});
}

function abandoned(data: JsonObject): JsonObject {
  const topicId = "D06-F04-A07", b = base(data), [a, middle, c] = b.candles;
  const bullish = a.direction === "bearish" && c.direction === "bullish", bearish = a.direction === "bullish" && c.direction === "bearish";
  const direction = bullish ? "bullish" : bearish ? "bearish" : "none", required = bullish ? "downtrend" : bearish ? "uptrend" : null;
  if (b.bodyScale === null || b.rangeScale === null) return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, direction, {}, {});
  const longFloor = 1.2 * b.bodyScale, dojiCeiling = 0.1 * b.rangeScale;
  let penetrationPrice = a.close, separated = false, penetrates = false;
  if (bullish) { penetrationPrice = a.close + b.penetration * a.body; separated = middle.high <= a.low - b.tick && c.low >= middle.high + b.tick; penetrates = c.close >= penetrationPrice; }
  else if (bearish) { penetrationPrice = a.close - b.penetration * a.body; separated = middle.low >= a.high + b.tick && c.high <= middle.low - b.tick; penetrates = c.close <= penetrationPrice; }
  return result(topicId, b.candles, b.context, required, b.bodyScale, b.rangeScale, b.count, direction, {opposite_outer_candles: bullish || bearish, first_long: a.body >= longFloor, middle_doji: middle.body <= dojiCeiling, full_range_isolation: separated, third_penetrates: penetrates}, {long_body_floor: longFloor, doji_body_ceiling: dojiCeiling, minimum_gap: b.tick, penetration_price: penetrationPrice, penetration_fraction: b.penetration});
}

export function calculate(topicId: string, inputs: JsonObject): JsonObject {
  if (inputs === null || typeof inputs !== "object" || Array.isArray(inputs)) throw new TypeError("inputs must be an object");
  if (["D06-F04-A01", "D06-F04-A02"].includes(topicId)) return star(topicId, inputs);
  if (["D06-F04-A03", "D06-F04-A04"].includes(topicId)) return soldiersOrCrows(topicId, inputs);
  if (topicId === "D06-F04-A05") return inside(inputs);
  if (topicId === "D06-F04-A06") return outside(inputs);
  if (topicId === "D06-F04-A07") return abandoned(inputs);
  throw new RangeError(`unsupported topic id ${topicId}`);
}