// Investor Flow — Derisking Strategy Library (Slice 23)
//
// ADR-0007: "winners have flexibility; losers only cut, never average down."
// Derisking suggestions are considerations, not instructions. No trade verbs.
//
// Pure/cache-deterministic: no I/O. Pure logic operating on position + market data.

// ─── Derisking Strategy Types ───────────────────────────────────────────────

export type DeriskingStrategyId =
  | 'scale_out_at_targets'
  | 'stop_trail_ema21_50'
  | 'thesis_based_partial'
  | 'option_protected_collar'
  | 'regime_cut'
  | 'correlation_driven';

export interface DeriskingStrategy {
  id: DeriskingStrategyId;
  name: string;
  description: string;
  alfredFraming: string;
  requiresOptionsSleeve: boolean;
}

export const DERISKING_STRATEGIES: DeriskingStrategy[] = [
  {
    id: 'scale_out_at_targets',
    name: 'Scale Out at Targets',
    description: 'Reduce partial position size as price reaches predefined profit targets. This adds flexibility — some position remains if the thesis continues to play out.',
    alfredFraming: 'Winners have flexibility. Scaling out at targets locks in some gains while leaving room for further upside.',
    requiresOptionsSleeve: false,
  },
  {
    id: 'stop_trail_ema21_50',
    name: 'Stop-Trail EMA 21/50',
    description: 'Trail a stop above the 21-day or 50-day EMA. This adapts the stop to volatility, allowing the position to breathe while protecting gains.',
    alfredFraming: 'Trailing stops adapt to changing conditions. A static stop ignores new information.',
    requiresOptionsSleeve: false,
  },
  {
    id: 'thesis_based_partial',
    name: 'Thesis-Based Partial Reduction',
    description: 'If the thesis is weakening but not fully invalidated, consider reducing position size rather than fully exiting. This acknowledges uncertainty without abandoning the thesis entirely.',
    alfredFraming: 'When the thesis weakens but is not broken, flexibility means adjusting size — not all or nothing.',
    requiresOptionsSleeve: false,
  },
  {
    id: 'option_protected_collar',
    name: 'Option-Protected Collar',
    description: 'Buy a protective put and sell a covered call to collar the position. This defines downside risk while partially financing the protection with call premium.',
    alfredFraming: 'A collar is insurance financed by someone else. You give up some upside to protect the downside.',
    requiresOptionsSleeve: true,
  },
  {
    id: 'regime_cut',
    name: 'Regime-Cut Reduction',
    description: 'When the market regime shifts to trending-down, consider reducing exposure across the portfolio. This is a macro-level derisking response to changed conditions.',
    alfredFraming: 'When the tide turns, reduce exposure. Fighting a regime shift is a common way winners become losers.',
    requiresOptionsSleeve: false,
  },
  {
    id: 'correlation_driven',
    name: 'Correlation-Driven Reduction',
    description: 'When multiple positions become highly correlated, consider reducing the most correlated ones. Concentrated correlation creates hidden portfolio risk.',
    alfredFraming: 'When everything moves together, you do not have diversification — you have one bet wearing many masks.',
    requiresOptionsSleeve: false,
  },
];

// ─── Derisking Suggestion Input ─────────────────────────────────────────────

export interface DeriskingInput {
  symbol: string;
  currentPrice: number;
  avgCost: number;
  shares: number;
  ema21?: number;
  ema50?: number;
  thesisStatus?: 'intact' | 'weakening' | 'broken';
  currentRegime?: 'trending-up' | 'trending-down' | 'range-bound';
  portfolioCorrelation?: number; // 0-1, how correlated this position is with others
  optionsUnlockState?: number; // 0-4, from ConvexityGate
  profitTargets?: number[]; // price levels
}

export interface DeriskingSuggestion {
  strategy: DeriskingStrategy;
  applicable: boolean;
  reason: string;
  details: string;
}

// ─── Suggestion Engine ──────────────────────────────────────────────────────

export function suggestDerisking(input: DeriskingInput): DeriskingSuggestion[] {
  const suggestions: DeriskingSuggestion[] = [];
  const inProfit = input.currentPrice > input.avgCost;

  for (const strat of DERISKING_STRATEGIES) {
    const suggestion = evaluateStrategy(strat, input, inProfit);
    if (suggestion.applicable) {
      suggestions.push(suggestion);
    }
  }

  return suggestions;
}

function evaluateStrategy(
  strat: DeriskingStrategy,
  input: DeriskingInput,
  inProfit: boolean,
): DeriskingSuggestion {
  switch (strat.id) {
    case 'scale_out_at_targets': {
      const targets = input.profitTargets ?? [];
      const hittingTarget = targets.some((t) => input.currentPrice >= t);
      return {
        strategy: strat,
        applicable: inProfit && hittingTarget,
        reason: hittingTarget
          ? `Price has reached a predefined target. Consider scaling out a portion.`
          : 'Price has not reached any predefined target.',
        details: strat.alfredFraming,
      };
    }

    case 'stop_trail_ema21_50': {
      const hasEMA = input.ema21 !== undefined || input.ema50 !== undefined;
      const belowEMA = input.ema21 !== undefined && input.currentPrice < input.ema21;
      return {
        strategy: strat,
        applicable: hasEMA && inProfit,
        reason: belowEMA
          ? `Price has fallen below EMA21. A trailing stop may help protect gains.`
          : 'Consider trailing a stop above EMA21 or EMA50 to protect gains while allowing the position to breathe.',
        details: strat.alfredFraming,
      };
    }

    case 'thesis_based_partial': {
      const weakening = input.thesisStatus === 'weakening';
      return {
        strategy: strat,
        applicable: weakening,
        reason: weakening
          ? 'Thesis is weakening but not broken. Consider a partial reduction rather than a full exit.'
          : 'Thesis is not weakening.',
        details: strat.alfredFraming,
      };
    }

    case 'option_protected_collar': {
      const hasOptionsSleeve = (input.optionsUnlockState ?? 0) >= 3;
      return {
        strategy: strat,
        applicable: hasOptionsSleeve && inProfit,
        reason: hasOptionsSleeve
          ? 'Options insurance sleeve is unlocked. A collar may define downside risk while partially financing protection.'
          : 'Options insurance sleeve is not unlocked. Collar strategy requires the insurance sleeve tier.',
        details: strat.alfredFraming,
      };
    }

    case 'regime_cut': {
      const regimeDown = input.currentRegime === 'trending-down';
      return {
        strategy: strat,
        applicable: regimeDown,
        reason: regimeDown
          ? 'Market regime has shifted to trending-down. Consider reducing exposure across the portfolio.'
          : 'Market regime is not trending-down.',
        details: strat.alfredFraming,
      };
    }

    case 'correlation_driven': {
      const highCorr = (input.portfolioCorrelation ?? 0) > 0.7;
      return {
        strategy: strat,
        applicable: highCorr,
        reason: highCorr
          ? `Position correlation is ${(input.portfolioCorrelation! * 100).toFixed(0)}%. Consider reducing the most correlated positions.`
          : 'Position correlation is within acceptable range.',
        details: strat.alfredFraming,
      };
    }
  }
}