// This file is part of Gear.

// Copyright (C) 2021-2024 Gear Technologies Inc.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

//! Runtime interface for gear node

#![allow(useless_deprecated, deprecated)]
#![cfg_attr(not(feature = "std"), no_std)]

extern crate alloc;

use byteorder::{ByteOrder, LittleEndian};
use codec::{Decode, Encode};
use gear_core::{
    gas::GasLeft,
    memory::{HostPointer, MemoryInterval},
    str::LimitedStr,
};
use gear_lazy_pages_common::{GlobalsAccessConfig, ProcessAccessError, Status};
use sp_runtime_interface::{
    pass_by::{Codec, PassBy},
    runtime_interface,
};
use sp_std::{convert::TryFrom, mem, result::Result, vec::Vec};
#[cfg(feature = "std")]
use {
    ark_bls12_381::{G1Projective as G1, G2Affine, G2Projective as G2},
    ark_ec::{
        bls12::Bls12Config,
        hashing::{curve_maps::wb, map_to_curve_hasher::MapToCurveBasedHasher, HashToCurve},
    },
    ark_ff::fields::field_hashers::DefaultFieldHasher,
    ark_scale::ArkScale,
    gear_lazy_pages::LazyPagesStorage,
};

mod gear_sandbox;

#[cfg(feature = "std")]
pub use gear_sandbox::init as sandbox_init;
pub use gear_sandbox::sandbox;

const _: () = assert!(core::mem::size_of::<HostPointer>() >= core::mem::size_of::<usize>());

// Domain Separation Tag for signatures on G2.
pub const DST_G2: &[u8] = b"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_";

#[derive(Debug, Clone, Encode, Decode)]
#[codec(crate = codec)]
pub struct LazyPagesProgramContext {
    /// Wasm program memory addr.
    pub wasm_mem_addr: Option<HostPointer>,
    /// Wasm program memory size.
    pub wasm_mem_size: u32,
    /// Wasm program stack end page.
    pub stack_end: Option<u32>,
    /// The field contains prefix to a program's memory pages, i.e.
    /// `program_id` + `memory_infix`.
    pub program_key: Vec<u8>,
    /// Globals config to access globals inside lazy-pages.
    pub globals_config: GlobalsAccessConfig,
    /// Lazy-pages access costs.
    pub costs: Vec<u64>,
}

impl PassBy for LazyPagesProgramContext {
    type PassBy = Codec<LazyPagesProgramContext>;
}

#[derive(Debug, Clone, Encode, Decode)]
#[codec(crate = codec)]
pub struct LazyPagesInitContext {
    pub page_sizes: Vec<u32>,
    pub global_names: Vec<LimitedStr<'static>>,
    pub pages_storage_prefix: Vec<u8>,
}

impl From<gear_lazy_pages_common::LazyPagesInitContext> for LazyPagesInitContext {
    fn from(ctx: gear_lazy_pages_common::LazyPagesInitContext) -> Self {
        let gear_lazy_pages_common::LazyPagesInitContext {
            page_sizes,
            global_names,
            pages_storage_prefix,
        } = ctx;

        Self {
            page_sizes,
            global_names,
            pages_storage_prefix,
        }
    }
}

impl From<LazyPagesInitContext> for gear_lazy_pages_common::LazyPagesInitContext {
    fn from(ctx: LazyPagesInitContext) -> Self {
        let LazyPagesInitContext {
            page_sizes,
            global_names,
            pages_storage_prefix,
        } = ctx;

        Self {
            page_sizes,
            global_names,
            pages_storage_prefix,
        }
    }
}

impl PassBy for LazyPagesInitContext {
    type PassBy = Codec<LazyPagesInitContext>;
}

#[derive(Debug, Default)]
struct SpIoProgramStorage;

#[cfg(feature = "std")]
impl LazyPagesStorage for SpIoProgramStorage {
    fn page_exists(&self, key: &[u8]) -> bool {
        sp_io::storage::exists(key)
    }

    fn load_page(&mut self, key: &[u8], buffer: &mut [u8]) -> Option<u32> {
        sp_io::storage::read(key, buffer, 0)
    }
}

fn deserialize_mem_intervals(bytes: &[u8], intervals: &mut Vec<MemoryInterval>) {
    let mem_interval_size = mem::size_of::<MemoryInterval>();
    for chunk in bytes.chunks_exact(mem_interval_size) {
        // can't panic because of chunks_exact
        intervals.push(MemoryInterval::try_from_bytes(chunk).unwrap());
    }
}

#[derive(Debug, Clone, Encode, Decode)]
#[codec(crate = codec)]
pub enum ProcessAccessErrorVer1 {
    OutOfBounds,
    GasLimitExceeded,
    GasAllowanceExceeded,
}

/// Runtime interface for gear node and runtime.
/// Note: name is expanded as gear_ri
#[runtime_interface]
pub trait GearRI {
    fn pre_process_memory_accesses(
        reads: &[MemoryInterval],
        writes: &[MemoryInterval],
        gas_left: (GasLeft,),
    ) -> (GasLeft, Result<(), ProcessAccessErrorVer1>) {
        let mut gas_left = gas_left.0;
        let gas_before = gas_left.gas;
        let res = gear_lazy_pages::pre_process_memory_accesses(reads, writes, &mut gas_left.gas);

        // Support charge for allowance otherwise DB will be corrupted.
        gas_left.allowance = gas_left
            .allowance
            .saturating_sub(gas_before.saturating_sub(gas_left.gas));

        match res {
            Ok(_) => {
                if gas_left.allowance > 0 {
                    (gas_left, Ok(()))
                } else {
                    (gas_left, Err(ProcessAccessErrorVer1::GasAllowanceExceeded))
                }
            }
            Err(ProcessAccessError::OutOfBounds) => {
                (gas_left, Err(ProcessAccessErrorVer1::OutOfBounds))
            }
            Err(ProcessAccessError::GasLimitExceeded) => {
                (gas_left, Err(ProcessAccessErrorVer1::GasLimitExceeded))
            }
        }
    }

    #[version(2)]
    fn pre_process_memory_accesses(reads: &[u8], writes: &[u8], gas_bytes: &mut [u8; 8]) -> u8 {
        let mem_interval_size = mem::size_of::<MemoryInterval>();
        let reads_len = reads.len();
        let writes_len = writes.len();

        let mut reads_intervals = Vec::with_capacity(reads_len / mem_interval_size);
        deserialize_mem_intervals(reads, &mut reads_intervals);
        let mut writes_intervals = Vec::with_capacity(writes_len / mem_interval_size);
        deserialize_mem_intervals(writes, &mut writes_intervals);

        let mut gas_counter = LittleEndian::read_u64(gas_bytes);

        let res = match gear_lazy_pages::pre_process_memory_accesses(
            &reads_intervals,
            &writes_intervals,
            &mut gas_counter,
        ) {
            Ok(_) => 0,
            Err(err) => err.into(),
        };

        LittleEndian::write_u64(gas_bytes, gas_counter);

        res
    }

    fn lazy_pages_status() -> (Status,) {
        (gear_lazy_pages::status()
            .unwrap_or_else(|err| unreachable!("Cannot get lazy-pages status: {err}")),)
    }

    /// Init lazy-pages.
    /// Returns whether initialization was successful.
    fn init_lazy_pages(ctx: LazyPagesInitContext) -> bool {
        use gear_lazy_pages::LazyPagesVersion;

        gear_lazy_pages::init(LazyPagesVersion::Version1, ctx.into(), SpIoProgramStorage)
            .map_err(|err| log::error!("Cannot initialize lazy-pages: {}", err))
            .is_ok()
    }

    /// Init lazy pages context for current program.
    /// Panic if some goes wrong during initialization.
    fn init_lazy_pages_for_program(ctx: LazyPagesProgramContext) {
        let wasm_mem_addr = ctx.wasm_mem_addr.map(|addr| {
            usize::try_from(addr)
                .unwrap_or_else(|err| unreachable!("Cannot cast wasm mem addr to `usize`: {}", err))
        });

        gear_lazy_pages::initialize_for_program(
            wasm_mem_addr,
            ctx.wasm_mem_size,
            ctx.stack_end,
            ctx.program_key,
            Some(ctx.globals_config),
            ctx.costs,
        )
        .map_err(|e| e.to_string())
        .expect("Cannot initialize lazy pages for current program");
    }

    /// Mprotect all wasm mem buffer except released pages.
    /// If `protect` argument is true then restrict all accesses to pages,
    /// else allows read and write accesses.
    fn mprotect_lazy_pages(protect: bool) {
        if protect {
            gear_lazy_pages::set_lazy_pages_protection()
        } else {
            gear_lazy_pages::unset_lazy_pages_protection()
        }
        .map_err(|err| err.to_string())
        .expect("Cannot set/unset mprotection for lazy pages");
    }

    fn change_wasm_memory_addr_and_size(addr: Option<HostPointer>, size: Option<u32>) {
        // `as usize` is safe, because of const assert above.
        gear_lazy_pages::change_wasm_mem_addr_and_size(addr.map(|addr| addr as usize), size)
            .unwrap_or_else(|err| unreachable!("Cannot set new wasm addr and size: {err}"));
    }

    fn write_accessed_pages() -> Vec<u32> {
        gear_lazy_pages::write_accessed_pages()
            .unwrap_or_else(|err| unreachable!("Cannot get write accessed pages: {err}"))
    }

    // Bellow goes deprecated runtime interface functions.
}

/// For debug using in benchmarks testing.
/// In wasm runtime is impossible to interact with OS functionality,
/// this interface allows to do it partially.
#[runtime_interface]
pub trait GearDebug {
    fn println(msg: &[u8]) {
        println!("{}", sp_std::str::from_utf8(msg).unwrap());
    }

    fn file_write(path: &str, data: Vec<u8>) {
        use std::{fs::File, io::Write};

        let mut file = File::create(path).unwrap();
        file.write_all(&data).unwrap();
    }

    fn file_read(path: &str) -> Vec<u8> {
        use std::{fs::File, io::Read};

        let mut file = File::open(path).unwrap();
        let mut data = Vec::new();
        file.read_to_end(&mut data).unwrap();
        data
    }

    fn time_in_nanos() -> u128 {
        use std::time::SystemTime;

        SystemTime::now()
            .duration_since(SystemTime::UNIX_EPOCH)
            .unwrap()
            .as_nanos()
    }
}

/// Describes possible errors for `GearBls12_381`.
#[repr(u32)]
enum GearBls12_381Error {
    /// Failed to decode an array of G1-points.
    Decode,
    /// The array of G1-points is empty.
    EmptyPointList,
    /// Failed to create `MapToCurveBasedHasher`.
    MapperCreation,
    /// Failed to map a message to a G2-point.
    MessageMapping,
}

impl From<GearBls12_381Error> for u32 {
    fn from(value: GearBls12_381Error) -> Self {
        value as u32
    }
}

#[runtime_interface]
pub trait GearBls12_381 {
    /// Aggregate provided G1-points. Useful for cases with hundreds or more items.
    /// Accepts scale-encoded `ArkScale<Vec<G1Projective>>`.
    /// Result is scale-encoded `ArkScale<G1Projective>`.
    fn aggregate_g1(points: &[u8]) -> Result<Vec<u8>, u32> {
        type ArkScale<T> = ark_scale::ArkScale<T, { ark_scale::HOST_CALL }>;

        let ArkScale(points) = ArkScale::<Vec<G1>>::decode(&mut &points[..])
            .map_err(|_| u32::from(GearBls12_381Error::Decode))?;

        let point_first = points
            .first()
            .ok_or(u32::from(GearBls12_381Error::EmptyPointList))?;

        let point_aggregated = points
            .iter()
            .skip(1)
            .fold(*point_first, |aggregated, point| aggregated + *point);

        Ok(ArkScale::<G1>::from(point_aggregated).encode())
    }

    /// Map a message to G2Affine-point using the domain separation tag from `milagro_bls`.
    /// Result is encoded `ArkScale<G2Affine>`.
    fn map_to_g2affine(message: &[u8]) -> Result<Vec<u8>, u32> {
        type ArkScale<T> = ark_scale::ArkScale<T, { ark_scale::HOST_CALL }>;
        type WBMap = wb::WBMap<<ark_bls12_381::Config as Bls12Config>::G2Config>;

        let mapper =
            MapToCurveBasedHasher::<G2, DefaultFieldHasher<sha2::Sha256>, WBMap>::new(DST_G2)
                .map_err(|_| u32::from(GearBls12_381Error::MapperCreation))?;

        let point = mapper
            .hash(message)
            .map_err(|_| u32::from(GearBls12_381Error::MessageMapping))?;

        Ok(ArkScale::<G2Affine>::from(point).encode())
    }
}