#![allow(dead_code)]
extern crate core;
use core::cell::UnsafeCell;
use memory::{VMem, CPUBus};
use cartridge::{Cartridge, BankType, MirrorType};

pub trait Mapper : VMem {
    fn get_cart(&self) -> &Cartridge;
    fn tick(&mut self, _bus: &CPUBus) {}
}

pub struct RefMapper<'a> {
    mapper: UnsafeCell<&'a mut Mapper>
}

impl<'a> RefMapper<'a> {
    pub fn new(mapper: &'a mut Mapper) -> Self {
        RefMapper { mapper: UnsafeCell::new(mapper) }
    }

    #[inline(always)]
    pub fn get_mut(&self) -> &'a mut Mapper {
        unsafe { *self.mapper.get() }
    }
}

impl<'a> core::ops::Deref for RefMapper<'a> {
    type Target = &'a mut Mapper;
    #[inline(always)]
    fn deref(&self) -> &&'a mut Mapper {
        unsafe { &*self.mapper.get() }
    }
}

pub struct Mapper1<'a, C> where C: Cartridge {
    cart: C,
    prg_banks: [&'a [u8]; 2],
    chr_banks: [&'a mut [u8]; 2],
    sram: &'a mut [u8],
    ctl_reg: u8,
    load_reg: u8,
    prg_nbank: usize, /* num of 16k PRG ROM banks */
    chr_nbank: usize /* num of 8k PRG ROM banks */
}

impl<'a, C> VMem for Mapper1<'a, C> where C: Cartridge {
    fn read(&self, addr: u16) -> u8 {
        let addr = addr as usize;
        match addr >> 12 {
            /* [0x0000..0x2000) */
            0 | 1 => self.chr_banks[(addr >> 12) & 1][addr & 0xfff],
            /* [0x2000..0x6000) */
            2 | 3 | 4 | 5 => panic!("unmapped address: 0x{:04x}", addr),
            /* [0x6000..0x8000) */
            6 | 7 => self.sram[addr - 0x6000],
            /* [0x8000..0xffff] */
            _ => self.prg_banks[(addr >> 14) & 1][addr & 0x3fff]
        }
    }

    fn write(&mut self, addr: u16, data: u8) {
        let addr = addr as usize;
        match addr >> 12 {
            /* [0x0000..0x2000) */
            0 | 1 => self.chr_banks[(addr >> 12) & 1][addr & 0xfff] = data,
            /* [0x2000..0x6000) */
            2 | 3 | 4 | 5 => panic!("unmapped address: 0x{:04x}", addr),
            /* [0x6000..0x8000) */
            6 | 7 => self.sram[addr - 0x6000] = data,
            /* [0x8000..0xffff] */
            _ => self.write_loadreg(addr as u16, data)
        }
    }
}

impl<'a, C> Mapper1<'a, C> where C: Cartridge {
    pub fn new(cart: C) -> Self {
        let prg_nbank = cart.get_size(BankType::PrgRom) >> 14;
        let chr_nbank = cart.get_size(BankType::ChrRom) >> 13;
        unsafe {
            let mut m = Mapper1{cart,
                        prg_nbank,
                        chr_nbank,
                        load_reg: 0x10,
                        ctl_reg: 0x0c,
                        prg_banks: core::mem::uninitialized(),
                        chr_banks: core::mem::uninitialized(),
                        sram: core::mem::uninitialized()};
            {
                let c = &mut m.cart;
                    m.prg_banks = [
                        c.get_bank(0, 0x4000, BankType::PrgRom),
                        c.get_bank((prg_nbank - 1) << 14, 0x4000, BankType::PrgRom)
                    ];
                    m.chr_banks = [
                        c.get_bank(0, 0x1000, BankType::ChrRom),
                        c.get_bank(0x1000, 0x1000, BankType::ChrRom)
                    ];
                    m.sram = c.get_bank(0, 0x2000, BankType::Sram);
            }
            m
        }
    }

    fn write_loadreg(&mut self, addr: u16, data: u8) {
        if data & 0x80 == 0x80 {
            self.ctl_reg |= 0x0c;
            self.load_reg = 0x10;
            return
        }
        let triggered = self.load_reg & 1 == 1;
        self.load_reg = (self.load_reg >> 1) | ((data & 1) << 4);
        if !triggered { return }

        let load_reg = self.load_reg;
        match (addr >> 13) & 3 {
            0x0 => {
                self.ctl_reg = load_reg;
                self.cart.set_mirror_type(match load_reg & 3 {
                    0x0 => MirrorType::Single0,
                    0x1 => MirrorType::Single1,
                    0x2 => MirrorType::Vertical,
                    _ => MirrorType::Horizontal
                });
            },
            0x1 => {
                match (self.ctl_reg >> 4) & 1 {
                    0x0 => {
                        let base = ((load_reg & 0xfe) as usize % self.chr_nbank) << 13;
                        self.chr_banks = [
                            self.cart.get_bank(base, 0x1000, BankType::ChrRom),
                            self.cart.get_bank(base + 0x1000, 0x1000, BankType::ChrRom)];
                    },
                    _ =>
                        self.chr_banks[0] = self.cart.get_bank(
                            (load_reg as usize % (self.chr_nbank << 1)) << 12,
                            0x1000, BankType::ChrRom)
                }
            },
            0x2 => {
                if (self.ctl_reg >> 4) & 1 == 1 {
                    self.chr_banks[1] = self.cart.get_bank(
                            (load_reg as usize % (self.chr_nbank << 1)) << 12,
                            0x1000, BankType::ChrRom)
                }
            },
            0x3 => {
                let load_reg = load_reg & 0xf;
                match (self.ctl_reg >> 2) & 3 {
                    0x0 | 0x1 => {
                        let base = ((load_reg & 0xfe) as usize % (self.prg_nbank >> 1)) << 15;
                        self.prg_banks = [
                            self.cart.get_bank(base, 0x4000, BankType::PrgRom),
                            self.cart.get_bank(base + 0x4000, 0x4000, BankType::PrgRom)
                        ];
                    },
                    0x2 => self.prg_banks = [
                            self.cart.get_bank(0, 0x4000, BankType::PrgRom),
                            self.cart.get_bank((load_reg as usize % self.prg_nbank) << 14,
                                                0x4000, BankType::PrgRom)],
                    0x3 => self.prg_banks = [
                            self.cart.get_bank((load_reg as usize % self.prg_nbank) << 14,
                                                0x4000, BankType::PrgRom),
                            self.cart.get_bank((self.prg_nbank - 1) << 14,
                                                0x4000, BankType::PrgRom)],
                    _ => ()
                }
            },
            _ => ()
        }
        self.load_reg = 0x10;
    }
}

impl<'a, C> Mapper for Mapper1<'a, C> where C: Cartridge {
    fn get_cart(&self) -> &Cartridge {&self.cart}
}

pub struct Mapper2<'a, C> where C: Cartridge {
    cart: C,
    prg_banks: [&'a [u8]; 2],
    chr_bank: &'a mut [u8],
    sram: &'a mut [u8],
    prg_nbank: usize
}

impl<'a, C> VMem for Mapper2<'a, C> where C: Cartridge {
    fn read(&self, addr: u16) -> u8 {
        let addr = addr as usize;
        match addr >> 12 {
            /* [0x0000..0x2000) */
            0 | 1 => self.chr_bank[addr],
            /* [0x2000..0x6000) */
            2 | 3 | 4 | 5 => panic!("unmapped address: 0x{:04x}", addr),
            /* [0x6000..0x8000) */
            6 | 7 => self.sram[addr - 0x6000],
            /* [0x8000..0xffff] */
            _ => self.prg_banks[(addr >> 14) & 1][addr & 0x3fff]
        }
    }

    fn write(&mut self, addr: u16, data: u8) {
        let addr = addr as usize;
        match addr >> 12 {
            /* [0x0000..0x2000) */
            0 | 1 => self.chr_bank[addr] = data,
            /* [0x2000..0x6000) */
            2 | 3 | 4 | 5 => panic!("unmapped address: 0x{:04x}", addr),
            /* [0x6000..0x8000) */
            6 | 7 => self.sram[addr - 0x6000] = data,
            /* [0x8000..0xffff] */
            _ => self.prg_banks[0] =
                    self.cart.get_bank(
                        ((data as usize) % self.prg_nbank) << 14,
                        0x4000,
                        BankType::PrgRom)
        }
    }
}

impl<'a, C> Mapper2<'a, C> where C: Cartridge {
    pub fn new(cart: C) -> Self {
        let nbank = cart.get_size(BankType::PrgRom) >> 14;
        unsafe {
            let mut m = Mapper2{cart,
                        prg_nbank: nbank,
                        prg_banks: core::mem::uninitialized(),
                        chr_bank: core::mem::uninitialized(),
                        sram: core::mem::uninitialized()};
            {
                let c = &mut m.cart;
                    m.prg_banks = [
                        c.get_bank(0, 0x4000, BankType::PrgRom),
                        c.get_bank((nbank - 1) << 14, 0x4000, BankType::PrgRom)
                    ];
                    m.chr_bank = c.get_bank(0, 0x2000, BankType::ChrRom);
                    m.sram = c.get_bank(0, 0x2000, BankType::Sram);
            }
            m
        }
    }
}

impl<'a, C> Mapper for Mapper2<'a, C> where C: Cartridge {
    fn get_cart(&self) -> &Cartridge {&self.cart}
}

pub struct Mapper4<'a, C> where C: Cartridge {
    cart: C,
    prg_banks: [&'a [u8]; 4],
    chr_banks: [&'a mut [u8]; 8],
    sram: &'a mut [u8],
    prg_nbank: usize, /* num of 16k PRG ROM banks */
    chr_nbank: usize, /* num of 8k PRG ROM banks */
    chr_inv: u8,
    prg_mode: u8,
    reg_idx: u8,
    regs: [u8; 8], /* 4 pairs of registers */
    irq_reload: u8,
    irq_counter: u8,
    irq_enable: bool
}

impl<'a, C> VMem for Mapper4<'a, C> where C: Cartridge {
    fn read(&self, addr: u16) -> u8 {
        let addr = addr as usize;
        match addr >> 12 {
            /* [0x0000..0x2000) */
            0 | 1 => self.chr_banks[addr >> 10][addr & 0x3ff],
            /* [0x2000..0x6000) */
            2 | 3 | 4 | 5 => panic!("unmapped address: 0x{:04x}", addr),
            /* [0x6000..0x8000) */
            6 | 7 => self.sram[addr - 0x6000],
            /* [0x8000..0xffff] */
            _ => {
                let addr = addr - 0x8000;
                self.prg_banks[addr >> 13][addr & 0x1fff]
            }
        }
    }

    fn write(&mut self, addr: u16, data: u8) {
        let addr = addr as usize;
        match addr >> 12 {
            /* [0x0000..0x2000) */
            0 | 1 => self.chr_banks[addr >> 10][addr & 0x3ff] = data,
            /* [0x2000..0x6000) */
            2 | 3 | 4 | 5 => panic!("unmapped address: 0x{:04x}", addr),
            /* [0x6000..0x8000) */
            6 | 7 => self.sram[addr - 0x6000] = data,
            /* [0x8000..0xa000) */
            8 | 9 => match addr & 1 {
                0 => self.write_select_reg(data),
                _ => self.write_bank_data(data)
            },
            /* [0xa000..0xc000) */
            0xa | 0xb => match addr & 1 {
                0 => self.write_mirror(data),
                _ => ()
            },
            /* [0xc000..0xe000) */
            0xc | 0xd => match addr & 1 {
                0 => self.irq_reload = data,
                _ => self.irq_counter = 0
            },
            /* [0xe000..0xffff] */
            _ => match addr & 1 {
                0 => self.irq_enable = false,
                _ => self.irq_enable = true
            }
        }
    }
}

impl<'a, C> Mapper4<'a, C> where C: Cartridge {
    #[inline(always)]
    fn write_select_reg(&mut self, data: u8) {
        self.prg_mode = (data >> 6) & 1;
        self.chr_inv = (data >> 7) & 1;
        self.reg_idx = data & 0x7;
        self.update_banks();
    }

    #[inline(always)]
    fn write_bank_data(&mut self, data: u8) {
        self.regs[self.reg_idx as usize] = data;
        self.update_banks();
    }

    #[inline(always)]
    fn write_mirror(&mut self, data: u8) {
        self.cart.set_mirror_type(match data & 1 {
            0 => MirrorType::Vertical,
            _ => MirrorType::Horizontal
        })
    }

    #[inline(always)]
    fn get_prgbank<'b>(&mut self, idx: u8) -> &'b mut [u8] {
        self.cart.get_bank(0x2000 * idx as usize, 0x2000, BankType::PrgRom)
    }

    #[inline(always)]
    fn get_chrbank<'b>(&mut self, idx: u8) -> &'b mut [u8] {
        self.cart.get_bank(0x400 * idx as usize, 0x400, BankType::ChrRom)
    }

    fn update_banks(&mut self) {
        macro_rules! make_arr {
            ($mt: ident, $m: ident, [$($x: expr), *]) => {
                [$({let t = ($x as usize % self.$m) as u8;
                    self.$mt(t)}), *]
            };
        }
        self.prg_banks = match self.prg_mode {
            0 => make_arr!(get_prgbank, prg_nbank, [
                self.regs[6],
                self.regs[7],
                (self.prg_nbank - 2) as u8,
                (self.prg_nbank - 1) as u8
            ]),
            _ => make_arr!(get_prgbank, prg_nbank, [
                (self.prg_nbank - 2) as u8,
                self.regs[7],
                self.regs[6],
                (self.prg_nbank - 1) as u8
            ])
        };
        self.chr_banks = match self.chr_inv {
            0 => make_arr!(get_chrbank, chr_nbank, [
                self.regs[0] & 0xfe,
                self.regs[0] | 0x01,
                self.regs[1] & 0xfe,
                self.regs[1] | 0x01,
                self.regs[2],
                self.regs[3],
                self.regs[4],
                self.regs[5]
            ]),
            _ => make_arr!(get_chrbank, chr_nbank, [
                self.regs[2],
                self.regs[3],
                self.regs[4],
                self.regs[5],
                self.regs[0] & 0xfe,
                self.regs[0] | 0x01,
                self.regs[1] & 0xfe,
                self.regs[1] | 0x01
            ]),
        };
    }

    pub fn new(cart: C) -> Self {
        let prg_nbank = cart.get_size(BankType::PrgRom) >> 13;
        let chr_nbank = cart.get_size(BankType::ChrRom) >> 10;
        unsafe {
            let mut m = Mapper4{cart,
                prg_nbank,
                chr_nbank,
                prg_mode: 0,
                chr_inv: 0,
                reg_idx: 0,
                regs: [0; 8],
                prg_banks: core::mem::uninitialized(),
                chr_banks: core::mem::uninitialized(),
                sram: core::mem::uninitialized(),
                irq_reload: 0,
                irq_counter: 0,
                irq_enable: false
            };
            m.prg_banks = [
                m.get_prgbank(0),
                m.get_prgbank(1),
                m.get_prgbank((prg_nbank - 2) as u8),
                m.get_prgbank((prg_nbank - 1) as u8)];
            m.chr_banks = [
                m.get_chrbank(0),
                m.get_chrbank(0),
                m.get_chrbank(0),
                m.get_chrbank(0),
                m.get_chrbank(0),
                m.get_chrbank(0),
                m.get_chrbank(0),
                m.get_chrbank(0)];
            {
                let c = &mut m.cart;
                m.sram = c.get_bank(0, 0x2000, BankType::Sram);
            }
            m
        }
    }
}

impl<'a, C> Mapper for Mapper4<'a, C> where C: Cartridge {
    fn get_cart(&self) -> &Cartridge {&self.cart}
    fn tick(&mut self, bus: &CPUBus) {
        let ppu = bus.get_ppu();
        if ppu.cycle != 260 {
            return
        }
        if ppu.scanline > 239 && ppu.scanline < 261 {
            return
        }
        if !ppu.get_show_bg() && !ppu.get_show_sp() {
            return
        }
        if self.irq_counter == 0 {
            self.irq_counter = self.irq_reload
        } else {
            self.irq_counter -= 1;
            if self.irq_counter == 0 && self.irq_enable {
                bus.get_cpu().trigger_irq();
            }
        }
    }
}