#include <U8g2lib.h>
#include <Encoder.h>
#include <EEPROM.h>

/* ================= HARDWARE ================= */
U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R2);
Encoder encoder(2, 3);

#define ENC_SW 4
#define BAUDRATE 38400

/* ================= ENCODER FILTER ================= */
#define ENC_DEBOUNCE_US 1200
long encLastRaw = 0;
unsigned long encLastTime = 0;

/* ================= PAGE ANIMATION ================= */
#define SWIPE_STEPS 10
#define FADE_STEPS  6
#define OLED_W 128

bool swipeActive = false;
uint8_t swipeStep = 0;
uint8_t fadeStep  = 0;
uint8_t prevPage  = 0;
int8_t swipeDir   = 1;

/* ================= EEPROM ================= */
#define EEPROM_MAGIC 0x55
#define EEPROM_ADDR  0

struct Settings {
  uint8_t magic;
  uint8_t vol, sub, pre;
  uint8_t bal, fad;
  uint8_t tre, mid, bas;
  uint8_t inVol;
} cfg;

/* ================= UI STATE ================= */
uint8_t page = 0, item = 0;
bool btnHeld = false;
unsigned long btnTime = 0;

/* ================= MUTE ANIMATION ================= */
bool muteState = false;
bool muteAnimating = false;
bool muteTarget = false;
uint8_t muteStep = 0;

/* ================= ANIMATION BUFFERS ================= */
uint8_t aVol,aSub,aTre,aMid,aBas,aBal,aFad,aIn;

/* ================= EEPROM ================= */
void loadEEPROM() {
  EEPROM.get(EEPROM_ADDR, cfg);
  if (cfg.magic != EEPROM_MAGIC) {
    cfg = {EEPROM_MAGIC,0x08,0x08,0,0x40,0x40,0x08,0x08,0x08,0x00};
    EEPROM.put(EEPROM_ADDR, cfg);
  }
}
void saveEEPROM() { EEPROM.put(EEPROM_ADDR, cfg); }

/* ================= UART ================= */
void sendFrame(uint8_t *f){ Serial.write(f,8); }
void sendP1(){ uint8_t f[8]={0x08,0x43,cfg.vol,cfg.sub,0xFF,0xFF,cfg.pre,0x00}; sendFrame(f); }
void sendMute(){ uint8_t f[8]={0x08,0x43,0xF0,0xFF,0xFF,0xFF,0xFF,0x00}; sendFrame(f); }
void sendP2(){ uint8_t f[8]={0x08,0x43,0xFF,0xFF,cfg.bal,cfg.fad,0xFF,0x00}; sendFrame(f); }
void sendP3(uint8_t m){
  uint8_t f[8]={0x08,0x44,0xFF,0xFF,0xFF,0x00,0x00,0x00};
  if(m==0)f[2]=cfg.tre;
  if(m==1)f[3]=cfg.mid;
  if(m==2)f[4]=cfg.bas;
  sendFrame(f);
}
void sendP4(){ uint8_t f[8]={0x08,0x43,cfg.inVol,0x0F,0x40,0x40,0x00,0x01}; sendFrame(f); }

/* ================= HELPERS ================= */
void animate(uint8_t &a,uint8_t t){ if(a<t)a++; else if(a>t)a--; }

void bar(int x,int y,int w,uint8_t v,bool sel){
  u8g2.drawFrame(x,y,w,8);
  u8g2.drawBox(x+1,y+1,map(v,0,15,0,w-2),6);
  if(sel) u8g2.drawFrame(x-2,y-2,w+4,12);
}
void slider(int x,int y,uint8_t v,uint8_t mn,uint8_t mx,bool sel){
  u8g2.drawHLine(x,y,108);
  int p=map(v,mn,mx,x,x+108);
  u8g2.drawDisc(p,y,sel?4:3);
}

/* ================= VECTOR ICONS ================= */
void drawVectorSpeaker(int x,int y){
  u8g2.drawTriangle(x,y+4,x+6,y,x+6,y+8);
  u8g2.drawBox(x+6,y+2,2,4);
}
void drawVectorMuteX(int x,int y){
  u8g2.drawLine(x,y,x+8,y+8);
  u8g2.drawLine(x+8,y,x,y+8);
}
void drawSpeakerWaves(uint8_t f){
  uint8_t r=f%3;
  u8g2.drawCircle(68,14,4+r);
  if(r>1) u8g2.drawCircle(68,14,7);
}

/* ================= MUTE CROSSFADE ================= */
void drawMuteCrossfade(bool toMute){
  drawVectorSpeaker(56,10);
  if(toMute){
    if(muteStep>1) drawVectorMuteX(56,10);
  } else {
    if(muteStep<FADE_STEPS-2) drawVectorMuteX(56,10);
  }
}

/* ================= PAGE DRAW ================= */
void drawPage(uint8_t p,int16_t xo){
  if(p==0){
    u8g2.drawStr(xo,10,"VOL"); bar(xo+30,3,90,15-aVol,item==0);
    u8g2.drawStr(xo,30,"SUB"); bar(xo+30,23,90,15-aSub,item==1);
    u8g2.drawStr(xo,50,"PRE");
    u8g2.drawCircle(xo+60,46,10);
    u8g2.drawStr(xo+55,50,cfg.pre==0?"P1":cfg.pre==1?"P2":cfg.pre==2?"P3":"P4");
  }
  if(p==1){
    u8g2.drawStr(xo,15,"BAL"); slider(xo+10,20,aBal,0x30,0x50,item==0);
    u8g2.drawStr(xo,45,"FAD"); slider(xo+10,50,aFad,0x30,0x50,item==1);
  }
  if(p==2){
    u8g2.drawStr(xo,15,"TRE"); slider(xo+10,20,aTre,1,15,item==0);
    u8g2.drawStr(xo,35,"MID"); slider(xo+10,40,aMid,1,15,item==1);
    u8g2.drawStr(xo,55,"BAS"); slider(xo+10,60,aBas,1,15,item==2);
  }
  if(p==3){
    u8g2.drawStr(xo,30,"IN VOL");
    bar(xo+30,25,90,240-aIn,true);
  }
}

/* ================= UI ================= */
void drawUI(){
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_6x12_tf);

  animate(aVol,cfg.vol); animate(aSub,cfg.sub);
  animate(aTre,cfg.tre); animate(aMid,cfg.mid); animate(aBas,cfg.bas);
  animate(aBal,cfg.bal); animate(aFad,cfg.fad); animate(aIn,cfg.inVol);

  if(muteAnimating){
    drawMuteCrossfade(muteTarget);
    muteStep++;
    if(muteStep>=FADE_STEPS){ muteAnimating=false; muteStep=0; }
    u8g2.sendBuffer();
    return;
  }

  if(muteState){
    drawVectorSpeaker(56,10);
    drawVectorMuteX(56,10);
    u8g2.setFont(u8g2_font_logisoso24_tf);
    u8g2.drawStr(18,48,"MUTE");
    u8g2.sendBuffer();
    return;
  }

  if(swipeActive){
    int off=map(swipeStep,0,SWIPE_STEPS,0,OLED_W);
    drawPage(prevPage,-off*swipeDir);
    drawPage(page,(OLED_W-off)*swipeDir);
    swipeStep++;
    if(swipeStep>=SWIPE_STEPS) swipeActive=false;
  } else {
    drawPage(page,0);
  }

  drawVectorSpeaker(56,10);
  drawSpeakerWaves(millis()/120);

  u8g2.sendBuffer();
}

/* ================= SETUP ================= */
void setup(){
  pinMode(ENC_SW,INPUT_PULLUP);
  Serial.begin(BAUDRATE);
  u8g2.begin();
  loadEEPROM();
}

/* ================= LOOP ================= */
void loop(){
  long raw=encoder.read();
  unsigned long now=micros();
  long delta=raw-encLastRaw;

  if(abs(delta)>=4 && now-encLastTime>ENC_DEBOUNCE_US){
    int d=(delta>0)?1:-1;
    encLastRaw=raw; encLastTime=now;

    if(page==0){
      if(item==0)cfg.vol=constrain(cfg.vol-d,0,15),sendP1();
      if(item==1)cfg.sub=constrain(cfg.sub-d,0,15),sendP1();
      if(item==2)cfg.pre=constrain(cfg.pre+d,0,3),sendP1();
    }
    if(page==1){
      if(item==0)cfg.bal=constrain(cfg.bal+d,0x30,0x50),sendP2();
      if(item==1)cfg.fad=constrain(cfg.fad+d,0x30,0x50),sendP2();
    }
    if(page==2){
      if(item==0)cfg.tre=constrain(cfg.tre+d,1,15),sendP3(0);
      if(item==1)cfg.mid=constrain(cfg.mid+d,1,15),sendP3(1);
      if(item==2)cfg.bas=constrain(cfg.bas+d,1,15),sendP3(2);
    }
    if(page==3){
      cfg.inVol=constrain(cfg.inVol+d,0,240);
      sendP4();
    }
    saveEEPROM();
  }

  if(!digitalRead(ENC_SW)){
    if(!btnHeld){ btnHeld=true; btnTime=millis(); }
  } else if(btnHeld){
    btnHeld=false;
    if(millis()-btnTime>1200){
      muteTarget=!muteState;
      muteAnimating=true;
      muteState=muteTarget;
      sendMute();
    } else {
      item++;
      if((page==0&&item>2)||(page==1&&item>1)||(page==2&&item>2)||(page==3)){
        item=0;
        prevPage=page;
        page=(page+1)%4;
        swipeActive=true;
        swipeStep=0;
      }
    }
  }

  drawUI();
}