use half::f16;
use pim_isa::{BankMode, File, Instruction, Kernel, PimConfig};

#[cxx::bridge(namespace = "pim_vm")]
mod ffi {
    pub enum BankMode {
        SingleBank,
        AllBank,
        PimAllBank,
    }

    extern "Rust" {
        type PimVM;

        fn new_pim_vm(num_pim_units: u32) -> Box<PimVM>;
        fn reset(&mut self);
        fn apply_config(&mut self, config: &str);
        fn bank_mode(&self) -> BankMode;
        fn execute_read(&mut self, bank_index: u32, address: u32, bank_data: &[u8]);
        fn execute_write(&mut self, bank_index: u32) -> [u8; 32];

        fn init_logger();
    }
}

fn init_logger() {
    env_logger::init();
}

const GRF_A_BIT_OFFSET: usize = 10;
const GRF_B_BIT_OFFSET: usize = 13;
const BURST_LENGTH: usize = 32;

const GRF_NUM_REGISTERS: usize = 8;
const SRF_A_NUM_REGISTERS: usize = 8;
const SRF_M_NUM_REGISTERS: usize = 8;

const FP_UNITS: usize = 16;
type GrfRegister = [f16; FP_UNITS];

#[derive(Clone, Debug)]
struct PimUnit {
    grf_a: [GrfRegister; GRF_NUM_REGISTERS],
    grf_b: [GrfRegister; GRF_NUM_REGISTERS],
    srf_a: [f16; SRF_A_NUM_REGISTERS],
    srf_m: [f16; SRF_A_NUM_REGISTERS],
    pc: u8,
    jump_counter: Option<u16>,
}

impl Default for PimUnit {
    fn default() -> Self {
        Self {
            grf_a: [[f16::ZERO; FP_UNITS]; GRF_NUM_REGISTERS],
            grf_b: [[f16::ZERO; FP_UNITS]; GRF_NUM_REGISTERS],
            srf_a: [f16::ZERO; SRF_A_NUM_REGISTERS],
            srf_m: [f16::ZERO; SRF_M_NUM_REGISTERS],
            pc: 0,
            jump_counter: None,
        }
    }
}

#[derive(Debug)]
struct PimVM {
    pim_units: Vec<PimUnit>,
    pim_config: pim_isa::PimConfig,
}

impl PimVM {
    fn reset(&mut self) {
        for unit in self.pim_units.iter_mut() {
            unit.pc = 0;
            unit.jump_counter = None;
        }
    }

    fn apply_config(&mut self, config_str: &str) {
        log::debug!("Config string:\n{config_str}");

        self.pim_config = serde_json::from_str::<pim_isa::PimConfig>(config_str).unwrap();
        self.reset();

        log::debug!("Apply pim config:\n{:?}", self.pim_config);
    }

    fn bank_mode(&self) -> ffi::BankMode {
        match self.pim_config.bank_mode {
            BankMode::SingleBank => ffi::BankMode::SingleBank,
            BankMode::AllBank => ffi::BankMode::AllBank,
            BankMode::PimAllBank => ffi::BankMode::PimAllBank,
        }
    }
}

fn new_pim_vm(num_pim_units: u32) -> Box<PimVM> {
    Box::new(PimVM {
        pim_units: vec![PimUnit::default(); num_pim_units as _],
        pim_config: PimConfig {
            bank_mode: BankMode::SingleBank,
            kernel: Kernel::NOP,
        },
    })
}

#[repr(C)]
struct BankData([f16; FP_UNITS]);

impl PimVM {
    pub fn execute_read(&mut self, bank_index: u32, address: u32, bank_data: &[u8]) {
        assert_eq!(bank_data.len(), BURST_LENGTH);

        let pim_unit = &mut self.pim_units[bank_index as usize];

        let mut inst = self.pim_config.kernel.0[pim_unit.pc as usize];
        pim_unit.pc += 1;

        let aam_grf_a_index = (address >> GRF_A_BIT_OFFSET) & 0b111;
        let aam_grf_b_index = (address >> GRF_B_BIT_OFFSET) & 0b111;

        log::debug!("PimUnit {bank_index} Execute PC {}: {inst:?}", pim_unit.pc);

        // The JUMP instruction is zero-cycle and not actually executed
        while let Instruction::JUMP { offset, count } = inst {
            pim_unit.jump_counter = match pim_unit.jump_counter {
                Some(jump_counter) => jump_counter.checked_sub(1),
                None => count.checked_sub(1),
            };

            if pim_unit.jump_counter != None {
                let new_pc = pim_unit.pc as i32 + offset as i32;

                if new_pc < 0 || new_pc >= 32 {
                    panic!("Invalid PC {new_pc} after JUMP: {inst:?}");
                }

                pim_unit.pc = new_pc as _;
                log::debug!("PimUnit {bank_index} New PC {new_pc}: {inst:?}");
            }

            inst = self.pim_config.kernel.0[pim_unit.pc as usize];
            pim_unit.pc += 1;
        }

        match inst {
            Instruction::NOP => (),
            Instruction::EXIT => {
                pim_unit.jump_counter = None;
                pim_unit.pc = 0;
            }
            Instruction::JUMP { .. } => unreachable!(),
            Instruction::MOV { src, dst } | Instruction::FILL { src, dst } => {
                let data = PimVM::load(src, pim_unit, &bank_data);
                PimVM::store(dst, pim_unit, &data);
            }
            Instruction::ADD {
                src0,
                mut src1,
                mut dst,
                aam,
            } => {
                if aam {
                    src1 = if let File::GrfA { index: _ } = src1 {
                        File::GrfA {
                            index: aam_grf_a_index as _,
                        }
                    } else {
                        panic!("Invalid operand in address-aligned-mode");
                    };

                    dst = if let File::GrfB { index: _ } = dst {
                        File::GrfB {
                            index: aam_grf_b_index as _,
                        }
                    } else {
                        panic!("Invalid operand in address-aligned-mode");
                    };
                }

                let data0 = PimVM::load(src0, pim_unit, &bank_data);
                let data1 = PimVM::load(src1, pim_unit, &bank_data);

                let sum: [f16; FP_UNITS] = data0
                    .into_iter()
                    .zip(data1)
                    .map(|(src0, src1)| src0 + src1)
                    .collect::<Vec<_>>()
                    .try_into()
                    .unwrap();

                PimVM::store(dst, pim_unit, &sum);
            }
            Instruction::MUL {
                src0,
                mut src1,
                mut dst,
                aam,
            } => {
                if aam {
                    src1 = if let File::GrfA { index: _ } = src1 {
                        File::GrfA {
                            index: aam_grf_a_index as _,
                        }
                    } else {
                        panic!("Invalid operand in address-aligned-mode");
                    };

                    dst = if let File::GrfB { index: _ } = dst {
                        File::GrfB {
                            index: aam_grf_b_index as _,
                        }
                    } else {
                        panic!("Invalid operand in address-aligned-mode");
                    };
                }

                let data0 = PimVM::load(src0, pim_unit, &bank_data);
                let data1 = PimVM::load(src1, pim_unit, &bank_data);

                let product: [f16; FP_UNITS] = data0
                    .into_iter()
                    .zip(data1)
                    .map(|(src0, src1)| src0 * src1)
                    .collect::<Vec<_>>()
                    .try_into()
                    .unwrap();

                PimVM::store(dst, pim_unit, &product);
            }
            Instruction::MAC {
                src0,
                mut src1,
                mut src2,
                mut dst,
                aam,
            }
            | Instruction::MAD {
                src0,
                mut src1,
                mut src2,
                mut dst,
                aam,
            } => {
                if aam {
                    src1 = if let File::GrfA { index: _ } = src1 {
                        File::GrfA {
                            index: aam_grf_a_index as _,
                        }
                    } else {
                        panic!("Invalid operand in address-aligned-mode");
                    };

                    src2 = if let File::GrfB { index: _ } = src2 {
                        File::GrfB {
                            index: aam_grf_b_index as _,
                        }
                    } else {
                        panic!("Invalid operand in address-aligned-mode");
                    };

                    dst = if let File::GrfB { index: _ } = dst {
                        File::GrfB {
                            index: aam_grf_b_index as _,
                        }
                    } else {
                        panic!("Invalid operand in address-aligned-mode");
                    };
                }

                assert_eq!(src2, dst);

                let data0 = PimVM::load(src0, pim_unit, &bank_data);
                let data1 = PimVM::load(src1, pim_unit, &bank_data);
                let data2 = PimVM::load(src2, pim_unit, &bank_data);

                let product: [f16; FP_UNITS] = data0
                    .into_iter()
                    .zip(data1)
                    .map(|(src0, src1)| src0 * src1)
                    .collect::<Vec<_>>()
                    .try_into()
                    .unwrap();

                let sum: [f16; FP_UNITS] = product
                    .into_iter()
                    .zip(data2)
                    .map(|(product, src2)| product + src2)
                    .collect::<Vec<_>>()
                    .try_into()
                    .unwrap();

                log::debug!("{data0:?}\n{data1:?}\n{data2:?}\n{product:?}\n{sum:?}");
                PimVM::store(dst, pim_unit, &sum);
            }
        }
    }

    pub fn execute_write(&mut self, bank_index: u32) -> [u8; BURST_LENGTH] {
        let pim_unit = &mut self.pim_units[bank_index as usize];

        let current_pc = pim_unit.pc;
        pim_unit.pc += 1;

        let inst = &self.pim_config.kernel.0[current_pc as usize];

        log::debug!("PimUnit {bank_index} Execute PC {current_pc}: {inst:?}");

        let data = match inst {
            Instruction::FILL { src, dst } => {
                let data: [f16; FP_UNITS] = match src {
                    File::GrfA { index } => pim_unit.grf_a[*index as usize],
                    File::GrfB { index } => pim_unit.grf_b[*index as usize],
                    _ => panic!("Unsupported src operand: {src:?}"),
                };

                if *dst != File::Bank {
                    panic!("Unsupported dst operand: {dst:?}")
                }

                data
            }
            _ => panic!("Unsupported instruction for write: {inst:?}"),
        };

        unsafe { std::mem::transmute(data) }
    }

    fn load(src: File, pim_unit: &PimUnit, bank_data: &[u8]) -> [f16; FP_UNITS] {
        match src {
            File::GrfA { index } => pim_unit.grf_a[index as usize],
            File::GrfB { index } => pim_unit.grf_b[index as usize],
            File::SrfM { index } => [pim_unit.srf_m[index as usize]; FP_UNITS],
            File::SrfA { index } => [pim_unit.srf_a[index as usize]; FP_UNITS],
            File::Bank => unsafe { std::ptr::read(bank_data.as_ptr() as *const BankData).0 },
        }
    }

    fn store(dst: File, pim_unit: &mut PimUnit, data: &[f16; FP_UNITS]) {
        match dst {
            File::GrfA { index } => pim_unit.grf_a[index as usize] = data.clone(),
            File::GrfB { index } => pim_unit.grf_b[index as usize] = data.clone(),
            File::SrfM { index } => pim_unit.srf_m[index as usize] = data[0],
            File::SrfA { index } => pim_unit.srf_a[index as usize] = data[0],
            File::Bank => panic!("Unsupported dst operand: {dst:?}"),
        }
    }
}