/**
 * Product-agnostic celebration engine.
 *
 * Provides milestone triggers, haptic configs, confetti, sounds,
 * and positive reinforcement messages.
 * Pure client-side TS — no backend dependency.
 */

import type {
  Celebration,
  CelebrationConfig,
  CelebrationEngine,
  CelebrationTrigger,
} from './types.js';

const DEFAULT_CELEBRATIONS: Record<CelebrationTrigger, Celebration> = {
  task_completed: {
    id: 'task_completed',
    title: 'Task Done!',
    body: 'Great work completing that task!',
    emoji: '✅',
    hapticType: 'light',
    confetti: false,
    sound: 'chime',
  },
  streak_continued: {
    id: 'streak_continued',
    title: 'Streak Alive!',
    body: 'You kept your streak going — amazing consistency!',
    emoji: '🔥',
    hapticType: 'medium',
    confetti: false,
    sound: 'chime',
  },
  streak_milestone: {
    id: 'streak_milestone',
    title: 'Streak Milestone!',
    body: 'What an incredible streak — you are unstoppable!',
    emoji: '⭐',
    hapticType: 'heavy',
    confetti: true,
    sound: 'success',
  },
  achievement_unlocked: {
    id: 'achievement_unlocked',
    title: 'Achievement Unlocked!',
    body: 'You just unlocked a new achievement!',
    emoji: '🏆',
    hapticType: 'heavy',
    confetti: true,
    sound: 'success',
  },
  level_up: {
    id: 'level_up',
    title: 'Level Up!',
    body: 'You reached a new level — keep going!',
    emoji: '🚀',
    hapticType: 'heavy',
    confetti: true,
    sound: 'level_up',
  },
  personal_best: {
    id: 'personal_best',
    title: 'Personal Best!',
    body: 'You just set a new personal record!',
    emoji: '🥇',
    hapticType: 'heavy',
    confetti: true,
    sound: 'success',
  },
  milestone_reached: {
    id: 'milestone_reached',
    title: 'Milestone Reached!',
    body: 'Another milestone in the books — well done!',
    emoji: '🎯',
    hapticType: 'medium',
    confetti: true,
    sound: 'success',
  },
  goal_completed: {
    id: 'goal_completed',
    title: 'Goal Complete!',
    body: 'You achieved your goal — celebrate this win!',
    emoji: '🎉',
    hapticType: 'heavy',
    confetti: true,
    sound: 'success',
  },
  first_action: {
    id: 'first_action',
    title: 'First Step!',
    body: 'Every journey begins with a single step — great start!',
    emoji: '👣',
    hapticType: 'medium',
    confetti: true,
    sound: 'chime',
  },
  halfway: {
    id: 'halfway',
    title: 'Halfway There!',
    body: "You're halfway through — the finish line is in sight!",
    emoji: '⏳',
    hapticType: 'medium',
    confetti: false,
    sound: 'chime',
  },
  session_completed: {
    id: 'session_completed',
    title: 'Session Complete!',
    body: 'Another session done — you showed up and that matters!',
    emoji: '💪',
    hapticType: 'medium',
    confetti: false,
    sound: 'success',
  },
  session_started: {
    id: 'session_started',
    title: 'Session Started!',
    body: 'You just started — showing up is the hardest part!',
    emoji: '🌟',
    hapticType: 'light',
    confetti: false,
    sound: 'none',
  },
};

const POSITIVE_MESSAGES: string[] = [
  "You're doing amazing!",
  'Keep it up — every step counts!',
  "Look at you go — you're incredible!",
  'Your dedication is inspiring!',
  'Consistency is your superpower!',
  "You're making real progress!",
  'One step at a time — and you nailed it!',
  'Be proud of how far you have come!',
];

const POSITIVE_INCOMPLETE_MESSAGES: string[] = [
  'Every bit of progress counts!',
  'You showed up — that takes courage!',
  "It's okay to take a break — you'll come back stronger!",
  'Progress, not perfection!',
  'You started, and that matters most!',
  'Rest is part of the journey!',
  "You've done more than you think!",
  'Tomorrow is another opportunity!',
];

const TIMED_MILESTONES = [
  { fraction: 0.25, id: 'timed_25' },
  { fraction: 0.5, id: 'timed_50' },
  { fraction: 0.75, id: 'timed_75' },
  { fraction: 1.0, id: 'timed_100' },
];

const FALLBACK_CELEBRATION: Celebration = {
  id: 'generic',
  title: 'Nice!',
  body: 'Keep up the great work!',
  emoji: '🎉',
  hapticType: 'light',
  confetti: false,
  sound: 'chime',
};

export function createCelebrationEngine(config?: CelebrationConfig): CelebrationEngine {
  const customTriggers = config?.customTriggers ?? {};

  function getCelebration(trigger: CelebrationTrigger | string): Celebration {
    if (trigger in customTriggers) return customTriggers[trigger];
    if (trigger in DEFAULT_CELEBRATIONS) return DEFAULT_CELEBRATIONS[trigger as CelebrationTrigger];
    return { ...FALLBACK_CELEBRATION, id: trigger };
  }

  function getTimedCelebrations(
    elapsedMs: number,
    targetMs: number,
    shownIds: Set<string>
  ): Celebration[] {
    if (targetMs <= 0) return [];
    const progress = elapsedMs / targetMs;
    const results: Celebration[] = [];

    for (const milestone of TIMED_MILESTONES) {
      if (progress >= milestone.fraction && !shownIds.has(milestone.id)) {
        const percent = Math.round(milestone.fraction * 100);
        results.push({
          id: milestone.id,
          title: `${percent}% Complete!`,
          body: getPositiveMessage(percent),
          emoji: milestone.fraction === 1.0 ? '🎉' : '⏳',
          hapticType: milestone.fraction === 1.0 ? 'heavy' : 'medium',
          confetti: milestone.fraction >= 0.75,
          sound: milestone.fraction === 1.0 ? 'success' : 'chime',
        });
      }
    }

    return results;
  }

  function isPersonalBest(current: number, previous: number): boolean {
    return current > previous && previous >= 0;
  }

  function getPositiveMessage(progressPercent: number): string {
    const clamped = Math.max(0, Math.min(100, progressPercent));
    const index = Math.floor((clamped / 100) * (POSITIVE_MESSAGES.length - 1));
    return POSITIVE_MESSAGES[index];
  }

  function getPositiveIncompleteMessage(progressPercent: number): string {
    const clamped = Math.max(0, Math.min(100, progressPercent));
    const index = Math.floor((clamped / 100) * (POSITIVE_INCOMPLETE_MESSAGES.length - 1));
    return POSITIVE_INCOMPLETE_MESSAGES[index];
  }

  return {
    getCelebration,
    getTimedCelebrations,
    isPersonalBest,
    getPositiveMessage,
    getPositiveIncompleteMessage,
  };
}