// Copyright 2024 The NativeLink Authors. All rights reserved.

//

// Licensed under the Functional Source License, Version 1.1, Apache 2.0 Future License (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//    See LICENSE file for details

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

use core::cmp::{Eq, Ordering};

use core::hash::{BuildHasher, Hash};

use core::ops::{Deref, DerefMut};

use std::collections::HashMap;

use std::io::{Cursor, Write};

use std::{env, fmt};

use bytes::{Buf, BufMut, Bytes, BytesMut};

use nativelink_error::{Error, ResultExt, make_input_err};

use nativelink_metric::{

    MetricFieldData, MetricKind, MetricPublishKnownKindData, MetricsComponent,

};

use nativelink_proto::build::bazel::remote::execution::v2::Digest;

use prost::Message;

use rand::Rng;

use serde::de::Visitor;

use serde::ser::Error as _;

use serde::{Deserialize, Deserializer, Serialize, Serializer};

use tonic::Code;

use tracing::error;

pub use crate::fs;

#[derive(Default, Clone, Copy, Eq, PartialEq, Hash, wincode::SchemaRead, wincode::SchemaWrite)]

#[repr(C)]

pub struct DigestInfo {

    /// Raw hash in packed form.

    packed_hash: PackedHash,

    /// Possibly the size of the digest in bytes.

    size_bytes: u64,

}

impl MetricsComponent for DigestInfo {

    fn publish(

        &self,

        _kind: MetricKind,

        field_metadata: MetricFieldData,

    ) -> Result<MetricPublishKnownKindData, nativelink_metric::Error> {

        format!("{self}").publish(MetricKind::String, field_metadata)

    }

}

impl DigestInfo {

    pub const fn new(packed_hash: [u8; 32], size_bytes: u64) -> Self {

        Self {

            size_bytes,

            packed_hash: PackedHash(packed_hash),

        }

    }

    pub fn try_new<T>(hash: &str, size_bytes: T) -> Result<Self, Error>

    where

        T: TryInto<u64> + fmt::Display + Copy,

    {

        let packed_hash =

            PackedHash::from_hex(hash).err_tip(|| 
format!9
("Invalid sha256 hash: {hash}"))
?9
;

        let size_bytes = size_bytes

            .try_into()

            .map_err(|_| 
make_input_err!0
("Could not convert {} into u64", size_bytes))
?0
;

        // The proto `Digest` takes an i64, so to keep compatibility

        // we only allow sizes that can fit into an i64.

        if size_bytes > i64::MAX as u64 {

            return Err(make_input_err!(

                "Size bytes is too large: {} - max: {}",

                size_bytes,

                i64::MAX

            ));

        }

        Ok(Self {

            packed_hash,

            size_bytes,

        })

    }

    pub const fn zero_digest() -> Self {

        Self {

            size_bytes: 0,

            packed_hash: PackedHash::new(),

        }

    }

    pub const fn packed_hash(&self) -> &PackedHash {

        &self.packed_hash

    }

    pub const fn set_packed_hash(&mut self, packed_hash: [u8; 32]) {

        self.packed_hash = PackedHash(packed_hash);

    }

    pub const fn size_bytes(&self) -> u64 {

        self.size_bytes

    }

    /// Returns a struct that can turn the `DigestInfo` into a string.

    const fn stringifier(&self) -> DigestStackStringifier<'_> {

        DigestStackStringifier::new(self)

    }

}

/// Counts the number of digits a number needs if it were to be

/// converted to a string.

const fn count_digits(mut num: u64) -> usize {

    let mut count = 0;

    while num != 0 {

        count += 1;

        num /= 10;

    }

    count

}

/// An optimized version of a function that can convert a `DigestInfo`

/// into a str on the stack.

struct DigestStackStringifier<'a> {

    digest: &'a DigestInfo,

    /// Buffer that can hold the string representation of the `DigestInfo`.

    /// - Hex is '2 * sizeof(PackedHash)'.

    /// - Digits can be at most `count_digits(u64::MAX)`.

    /// - We also have a hyphen separator.

    buf: [u8; size_of::<PackedHash>() * 2 + count_digits(u64::MAX) + 1],

}

impl<'a> DigestStackStringifier<'a> {

    const fn new(digest: &'a DigestInfo) -> Self {

        DigestStackStringifier {

            digest,

            buf: [b'-'; size_of::<PackedHash>() * 2 + count_digits(u64::MAX) + 1],

        }

    }

    fn as_str(&mut self) -> Result<&str, Error> {

        // Populate the buffer and return the amount of bytes written

        // to the buffer.

        let len = {

            let mut cursor = Cursor::new(&mut self.buf[..]);

            let hex = self.digest.packed_hash.to_hex().map_err(|e| 
{0

                Error::from_std_err(Code::InvalidArgument, &e).append(format!(

                    "Could not convert PackedHash to hex - {:?}",

                    self.digest

                ))

            })?;

            cursor

                .write_all(&hex)

                .err_tip(|| 
format!0
("Could not write hex to buffer - {hex:?} - {hex:?}",))
?0
;

            // Note: We already have a hyphen at this point because we

            // initialized the buffer with hyphens.

            cursor.advance(1);

            cursor

                .write_fmt(format_args!("{}", self.digest.size_bytes()))

                .err_tip(|| 
format!0
("Could not write size_bytes to buffer - {hex:?}",))
?0
;

            cursor.position().try_into().map_err(|e| 
{0

                Error::from_std_err(Code::InvalidArgument, &e)

                    .append("Cursor position exceeds usize bounds")

            })?

        };

        // Convert the buffer into utf8 string.

        core::str::from_utf8(&self.buf[..len]).map_err(|e| 
{0

            Error::from_std_err(Code::InvalidArgument, &e).append(format!(

                "Could not convert [u8] to string - {} - {:?}",

                self.digest, self.buf

            ))

        })

    }

}

/// Custom serializer for `DigestInfo` because the default Serializer

/// would try to encode the data as a byte array, but we use {hex}-{size}.

impl Serialize for DigestInfo {

    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

    where

        S: Serializer,

    {

        let mut stringifier = self.stringifier();

        serializer.serialize_str(

            stringifier

                .as_str()

                .err_tip(|| "During serialization of DigestInfo")

                .map_err(S::Error::custom)
?0
,

        )

    }

}

/// Custom deserializer for `DigestInfo` because the default Deserializer

/// would try to decode the data as a byte array, but we use {hex}-{size}.

impl<'de> Deserialize<'de> for DigestInfo {

    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

    where

        D: Deserializer<'de>,

    {

        struct DigestInfoVisitor;

        impl Visitor<'_> for DigestInfoVisitor {

            type Value = DigestInfo;

            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {

                formatter.write_str("a string representing a DigestInfo")

            }

            fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>

            where

                E: serde::de::Error,

            {

                let Some((hash, size)) = s.split_once('-') else {

                    return Err(E::custom(

                        "Invalid DigestInfo format, expected '-' separator",

                    ));

                };

                let size_bytes = size

                    .parse::<u64>()

                    .map_err(|e| 
E::custom0
(
format!0
("Could not parse size_bytes: {e:?}")))
?0
;

                DigestInfo::try_new(hash, size_bytes)

                    .map_err(|e| 
E::custom1
(
format!1
("Could not create DigestInfo: {e:?}")))

            }

        }

        deserializer.deserialize_str(DigestInfoVisitor)

    }

}

impl fmt::Display for DigestInfo {

    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

        let mut stringifier = self.stringifier();

        f.write_str(

            stringifier

                .as_str()

                .err_tip(|| "During serialization of DigestInfo")

                .map_err(|e| 
{0

                    error!("Could not convert DigestInfo to string - {e:?}");

                    fmt::Error

                })?,

        )

    }

}

impl fmt::Debug for DigestInfo {

    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

        let mut stringifier = self.stringifier();

        match stringifier.as_str() {

            Ok(s) => f.debug_tuple("DigestInfo").field(&s).finish(),

            Err(e) => {

                error!("Could not convert DigestInfo to string - {e:?}");

                Err(fmt::Error)

            }

        }

    }

}

impl Ord for DigestInfo {

    fn cmp(&self, other: &Self) -> Ordering {

        self.packed_hash

            .cmp(&other.packed_hash)

            .then_with(|| self.size_bytes.cmp(&other.size_bytes))

    }

}

impl PartialOrd for DigestInfo {

    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {

        Some(self.cmp(other))

    }

}

impl TryFrom<Digest> for DigestInfo {

    type Error = Error;

    fn try_from(digest: Digest) -> Result<Self, Self::Error> {

        let 
packed_hash259
 = PackedHash::from_hex(&digest.hash)

            .err_tip(|| 
format!1
("Invalid sha256 hash: {}", digest.hash))
?1
;

        let size_bytes = digest.size_bytes.try_into().map_err(|e| 
{0

            Error::from_std_err(Code::InvalidArgument, &e)

                .append(format!("Could not convert {} into u64", digest.size_bytes))

        })?;

        Ok(Self {

            packed_hash,

            size_bytes,

        })

    }

}

impl TryFrom<&Digest> for DigestInfo {

    type Error = Error;

    fn try_from(digest: &Digest) -> Result<Self, Self::Error> {

        let packed_hash = PackedHash::from_hex(&digest.hash)

            .err_tip(|| format!("Invalid sha256 hash: {}", digest.hash))?;

        let size_bytes = digest.size_bytes.try_into().map_err(|e| {

            Error::from_std_err(Code::InvalidArgument, &e)

                .append(format!("Could not convert {} into u64", digest.size_bytes))

        })?;

        Ok(Self {

            packed_hash,

            size_bytes,

        })

    }

}

impl From<DigestInfo> for Digest {

    fn from(val: DigestInfo) -> Self {

        Self {

            hash: val.packed_hash.to_string(),

            size_bytes: val.size_bytes.try_into().unwrap_or_else(|e| 
{0

                error!("Could not convert {} into u64 - {e:?}", val.size_bytes);

                // This is a placeholder value that can help a user identify

                // that the conversion failed.

                -255

            }),

        }

    }

}

impl From<&DigestInfo> for Digest {

    fn from(val: &DigestInfo) -> Self {

        Self {

            hash: val.packed_hash.to_string(),

            size_bytes: val.size_bytes.try_into().unwrap_or_else(|e| 
{0

                error!("Could not convert {} into u64 - {e:?}", val.size_bytes);

                // This is a placeholder value that can help a user identify

                // that the conversion failed.

                -255

            }),

        }

    }

}

#[derive(

    Debug,

    Serialize,

    Deserialize,

    Default,

    Clone,

    Copy,

    Eq,

    PartialEq,

    Hash,

    PartialOrd,

    Ord,

    wincode::SchemaRead,

    wincode::SchemaWrite,

)]

pub struct PackedHash([u8; 32]);

const SIZE_OF_PACKED_HASH: usize = 32;

impl PackedHash {

    const fn new() -> Self {

        Self([0; SIZE_OF_PACKED_HASH])

    }

    fn from_hex(hash: &str) -> Result<Self, Error> {

        let mut packed_hash = [0u8; 32];

        hex::decode_to_slice(hash, &mut packed_hash).map_err(|e| 
{10

            Error::from_std_err(Code::InvalidArgument, &e)

                .append(format!("Invalid sha256 hash: {hash}"))

        })?;

        Ok(Self(packed_hash))

    }

    /// Converts the packed hash into a hex string.

    #[inline]

    fn to_hex(self) -> Result<[u8; SIZE_OF_PACKED_HASH * 2], fmt::Error> {

        let mut hash = [0u8; SIZE_OF_PACKED_HASH * 2];

        hex::encode_to_slice(self.0, &mut hash).map_err(|e| 
{0

            error!("Could not convert PackedHash to hex - {e:?} - {:?}", self.0);

            fmt::Error

        })?;

        Ok(hash)

    }

}

impl fmt::Display for PackedHash {

    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

        let hash = self.to_hex()
?0
;

        match core::str::from_utf8(&hash) {

            Ok(hash) => f.write_str(hash)
?0
,

            Err(_) => f.write_str(&format!("Could not convert hash to utf8 {:?}", self.0))?,

        }

        Ok(())

    }

}

impl Deref for PackedHash {

    type Target = [u8; 32];

    fn deref(&self) -> &Self::Target {

        &self.0

    }

}

impl DerefMut for PackedHash {

    fn deref_mut(&mut self) -> &mut Self::Target {

        &mut self.0

    }

}

// Simple utility trait that makes it easier to apply `.try_map` to Vec.

// This will convert one vector into another vector with a different type.

pub trait VecExt<T> {

    fn try_map<F, U>(self, f: F) -> Result<Vec<U>, Error>

    where

        Self: Sized,

        F: (Fn(T) -> Result<U, Error>) + Sized;

}

impl<T> VecExt<T> for Vec<T> {

    fn try_map<F, U>(self, f: F) -> Result<Vec<U>, Error>

    where

        Self: Sized,

        F: (Fn(T) -> Result<U, Error>) + Sized,

    {

        let mut output = Vec::with_capacity(self.len());

        for 
item6
 in self {

            output.push((f)(item)
?0
);

        }

        Ok(output)

    }

}

// Simple utility trait that makes it easier to apply `.try_map` to HashMap.

// This will convert one HashMap into another keeping the key the same, but

// different value type.

pub trait HashMapExt<K: Eq + Hash, T, S: BuildHasher> {

    fn try_map<F, U>(self, f: F) -> Result<HashMap<K, U, S>, Error>

    where

        Self: Sized,

        F: (Fn(T) -> Result<U, Error>) + Sized;

}

impl<K: Eq + Hash, T, S: BuildHasher + Clone> HashMapExt<K, T, S> for HashMap<K, T, S> {

    fn try_map<F, U>(self, f: F) -> Result<HashMap<K, U, S>, Error>

    where

        Self: Sized,

        F: (Fn(T) -> Result<U, Error>) + Sized,

    {

        let mut output = HashMap::with_capacity_and_hasher(self.len(), (*self.hasher()).clone());

        for (
k2
, 
v2
) in self {

            output.insert(k, (f)(v)
?0
);

        }

        Ok(output)

    }

}

// Utility to encode our proto into GRPC stream format.

pub fn encode_stream_proto<T: Message>(proto: &T) -> Result<Bytes, Box<dyn core::error::Error>> {

    // See below comment on spec.

    use core::mem::size_of;

    const PREFIX_BYTES: usize = size_of::<u8>() + size_of::<u32>();

    let mut buf = BytesMut::new();

    for _ in 
0..PREFIX_BYTES43
 {

        // Advance our buffer first.

        // We will backfill it once we know the size of the message.

        buf.put_u8(0);

    }

    proto.encode(&mut buf)
?0
;

    let len = buf.len() - PREFIX_BYTES;

    {

        let mut buf = &mut buf[0..PREFIX_BYTES];

        // See: https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#:~:text=Compressed-Flag

        // for more details on spec.

        // Compressed-Flag -> 0 / 1 # encoded as 1 byte unsigned integer.

        buf.put_u8(0);

        // Message-Length -> {length of Message} # encoded as 4 byte unsigned integer (big endian).

        buf.put_u32(u32::try_from(len)
?0
);

        // Message -> *{binary octet}.

    }

    Ok(buf.freeze())

}

/// Small utility to reseed the global RNG.

/// Done this way because we use it in a macro

/// and macro's can't load external crates.

#[inline]

pub fn reseed_rng_for_test() -> Result<(), Error> {

    rand::rng()

        .reseed()

        .map_err(|e| 
Error::from_std_err0
(
Code::InvalidArgument0
, 
&e0
).
append0
("Could not reseed RNG"))

}

/// Get temporary path from either `TEST_TMPDIR` or best effort temp directory if

/// not set.

pub fn make_temp_path(data: &str) -> String {

    #[cfg(target_family = "unix")]

    return format!(

        "{}/{}/{}",

        env::var("TEST_TMPDIR").unwrap_or_else(|_| env::temp_dir().to_str().unwrap().to_string()),

        rand::rng().random::<u64>(),

        data

    );

    #[cfg(target_family = "windows")]

    return format!(

        "{}\\{}\\{}",

        env::var("TEST_TMPDIR").unwrap_or_else(|_| env::temp_dir().to_str().unwrap().to_string()),

        rand::rng().random::<u64>(),

        data

    );

}

// Constant for PreconditionFailure

pub const VIOLATION_TYPE_MISSING: &str = "MISSING";