Multiple If statements for Arduino - arduino

Question

I'm new to this site and also the wonderful world of Arduino, I have been playing around with a Leonardo board and some Neopixel LEDS ( WS2812B ). I'm currently trying to set predefined colors on the LEDs with a single Pot, but also have an interrupt for a PIR sensor. I'm using the Fastled library since its great but at this point I seem to be stuck on the interrupt part. Any guidance will be appreciated !
#include "FastLED.h"
#define NUM_LEDS 3
#define DATA_PIN 6
#define PIR_PIN 2
int PIR_PIN = 0
// These constants won't change:
const int analogPin = A0; // pin that the sensor is attached to
CRGB leds[NUM_LEDS];
void setup() {
// initialize the LED pin as an output:
FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS);
// initialize serial communications:
pinMode(PIR_PIN, INPUT);
attachInterrupt(0, PIR_PIN, CHANGE);
}
void loop() {
// read the value of the potentiometer:
int analogValue = analogRead(analogPin);
if (analogPin < 1000)
{
leds[0] = CRGB::Red;
FastLED.show();// do Thing A
}
else if (analogPin < 500)
{
leds[0] = CRGB::Orange;
FastLED.show();// do Thing B
}
else if (analogPin < 250)
{
leds[0] = CRGB::Green;
FastLED.show();//do fuckity
}
else
{
leds[0] = CRGB::Purple;
FastLED.show();// do Thing C
}
}
void PIN_PIR () {
buttonState = digitalRead(PIR_PIN);
digitalWrite(DATA_PIN, buttonState);
}