/**
 * Value Change Animation Tests
 * Tests for animation behavior when gauge value changes
 */

describe('Value Change Animation', () => {
  describe('Animation Start Position', () => {
    it('should start animation from last rendered progress when available', () => {
      const lastRenderedProgress = 0.5;
      const prevPercent = 0;
      const isFirstAnimation = false;
      
      const hasLastRenderedProgress = lastRenderedProgress !== undefined && !isFirstAnimation;
      const animationStartPercent = hasLastRenderedProgress ? lastRenderedProgress : prevPercent;
      
      expect(animationStartPercent).toBe(0.5);
    });

    it('should start animation from prevPercent for first animation', () => {
      const lastRenderedProgress = 0.5;
      const prevPercent = 0;
      const isFirstAnimation = true;
      
      const hasLastRenderedProgress = lastRenderedProgress !== undefined && !isFirstAnimation;
      const animationStartPercent = hasLastRenderedProgress ? lastRenderedProgress : prevPercent;
      
      expect(animationStartPercent).toBe(0);
    });

    it('should start animation from prevPercent when no last rendered progress', () => {
      const lastRenderedProgress = undefined;
      const prevPercent = 0.3;
      const isFirstAnimation = false;
      
      const hasLastRenderedProgress = lastRenderedProgress !== undefined && !isFirstAnimation;
      const animationStartPercent = hasLastRenderedProgress ? lastRenderedProgress : prevPercent;
      
      expect(animationStartPercent).toBe(0.3);
    });
  });

  describe('Animation Duration', () => {
    it('should use configured duration for all animations', () => {
      const configuredDuration = 3000;
      expect(configuredDuration).toBe(3000);
    });

    it('should respect short durations for responsive updates', () => {
      const configuredDuration = 200;
      expect(configuredDuration).toBe(200);
    });
  });

  describe('Animation Delay', () => {
    it('should use configured delay for first animation', () => {
      const configuredDelay = 500;
      const isFirstAnimation = true;
      const effectiveDelay = isFirstAnimation ? configuredDelay : 0;
      
      expect(effectiveDelay).toBe(500);
    });

    it('should skip delay for subsequent animations', () => {
      const configuredDelay = 500;
      const isFirstAnimation = false;
      const effectiveDelay = isFirstAnimation ? configuredDelay : 0;
      
      expect(effectiveDelay).toBe(0);
    });
  });

  describe('Percentage Calculation', () => {
    it('should calculate percentage correctly', () => {
      const minValue = 0;
      const maxValue = 100;
      const value = 50;
      const percentage = (value - minValue) / (maxValue - minValue);
      
      expect(percentage).toBe(0.5);
    });

    it('should handle non-zero min values', () => {
      const minValue = 20;
      const maxValue = 80;
      const value = 50;
      const percentage = (value - minValue) / (maxValue - minValue);
      
      expect(percentage).toBe(0.5);
    });

    it('should handle negative values', () => {
      const minValue = -100;
      const maxValue = 100;
      const value = 0;
      const percentage = (value - minValue) / (maxValue - minValue);
      
      expect(percentage).toBe(0.5);
    });
  });

  describe('prevProgress Preservation (Bug Fix)', () => {
    /**
     * This test catches the critical bug where setupContext was resetting
     * prevProgress to 0 on every call, causing animations to always start from 0
     * instead of the current visual position.
     */
    it('should preserve prevProgress when rebuilding context (not first animation)', () => {
      // Simulate existing context with prevProgress at 0.6 (60% through animation)
      const existingContext = { prevProgress: 0.6 };
      const isFirstAnimation = false;
      
      // The new setupContext should preserve this value
      const existingPrevProgress = existingContext?.prevProgress;
      const newPrevProgress = isFirstAnimation ? 0 : (existingPrevProgress ?? 0);
      
      expect(newPrevProgress).toBe(0.6);
    });

    it('should reset prevProgress to 0 for first animation only', () => {
      const existingContext = { prevProgress: 0.6 };
      const isFirstAnimation = true;
      
      // First animation should start from 0 regardless of existing progress
      const existingPrevProgress = existingContext?.prevProgress;
      const newPrevProgress = isFirstAnimation ? 0 : (existingPrevProgress ?? 0);
      
      expect(newPrevProgress).toBe(0);
    });

    it('should handle undefined existing context gracefully', () => {
      const existingContext = undefined as any;
      const isFirstAnimation = false;
      
      const existingPrevProgress = existingContext?.prevProgress;
      const newPrevProgress = isFirstAnimation ? 0 : (existingPrevProgress ?? 0);
      
      // Should fall back to 0 when no existing context
      expect(newPrevProgress).toBe(0);
    });

    it('should use lastRenderedProgress as animation start when available', () => {
      const lastRenderedProgress = 0.75;
      const prevPercent = 0.5;
      const isFirstAnimation = false;
      
      const hasLastRenderedProgress = lastRenderedProgress !== undefined && !isFirstAnimation;
      const animationStartPercent = hasLastRenderedProgress ? lastRenderedProgress : prevPercent;
      
      // Should use lastRenderedProgress (0.75) not prevPercent (0.5)
      expect(animationStartPercent).toBe(0.75);
    });

    it('should NOT use lastRenderedProgress for first animation', () => {
      const lastRenderedProgress = 0.75;
      const prevPercent = 0;
      const isFirstAnimation = true;
      
      const hasLastRenderedProgress = lastRenderedProgress !== undefined && !isFirstAnimation;
      const animationStartPercent = hasLastRenderedProgress ? lastRenderedProgress : prevPercent;
      
      // First animation should use prevPercent (0) not lastRenderedProgress
      expect(animationStartPercent).toBe(0);
    });
  });
});