// ── Pre-Warning Cascade System ─────────────────────────────────
// Cascade presets aligned with PRD: Aggressive, Standard, Light, Minimal, None, Custom

export type CascadePreset = 'aggressive' | 'standard' | 'light' | 'minimal' | 'none' | 'custom';

export interface CascadeWarning {
  id: string;
  minutesBefore: number;
  fired: boolean;
  firedAt: number | null;
  scheduledTime: number; // epoch ms
}

export interface CascadeConfig {
  preset: CascadePreset;
  intervals: number[]; // minutes before target time
}

// Preset definitions (minutes before target)
export const CASCADE_PRESETS: Record<CascadePreset, number[]> = {
  aggressive: [240, 180, 120, 90, 60, 30, 15, 5, 1],
  standard: [120, 60, 30, 15, 5],
  light: [60, 15, 5],
  minimal: [15],
  none: [],
  custom: [],
};

export const CASCADE_PRESET_LABELS: Record<CascadePreset, string> = {
  aggressive: 'Aggressive',
  standard: 'Standard',
  light: 'Light',
  minimal: 'Minimal',
  none: 'None (fire only)',
  custom: 'Custom',
};

/**
 * Calculate all warning timestamps from target time and cascade intervals.
 * Filters out warnings that would be in the past relative to `now`.
 */
export function calculateCascadeWarnings(
  targetTime: number,
  intervals: number[],
  now: number = Date.now()
): CascadeWarning[] {
  return intervals
    .sort((a, b) => b - a) // largest first (earliest warning)
    .map((minutesBefore, idx) => {
      const scheduledTime = targetTime - minutesBefore * 60 * 1000;
      return {
        id: `w-${idx}-${minutesBefore}m`,
        minutesBefore,
        fired: scheduledTime <= now,
        firedAt: scheduledTime <= now ? scheduledTime : null,
        scheduledTime,
      };
    });
}

/**
 * Get the next unfired warning from a cascade.
 */
export function getNextWarning(warnings: CascadeWarning[]): CascadeWarning | null {
  return warnings.find((w) => !w.fired) ?? null;
}

/**
 * Check which warnings should fire given the current time.
 * Returns newly-fired warning IDs.
 */
export function checkWarnings(
  warnings: CascadeWarning[],
  now: number = Date.now()
): string[] {
  const newlyFired: string[] = [];
  for (const warning of warnings) {
    if (!warning.fired && warning.scheduledTime <= now) {
      warning.fired = true;
      warning.firedAt = now;
      newlyFired.push(warning.id);
    }
  }
  return newlyFired;
}

/**
 * Get intervals for a preset, or custom intervals if preset is 'custom'.
 */
export function getCascadeIntervals(config: CascadeConfig): number[] {
  if (config.preset === 'custom') {
    return [...config.intervals].sort((a, b) => b - a);
  }
  return CASCADE_PRESETS[config.preset];
}

/**
 * Format minutes into human-readable string.
 */
export function formatMinutesBefore(minutes: number): string {
  if (minutes >= 60) {
    const hours = Math.floor(minutes / 60);
    const remaining = minutes % 60;
    if (remaining === 0) return `${hours}h`;
    return `${hours}h ${remaining}m`;
  }
  return `${minutes}m`;
}