//! Common types of the protocol.
use std::borrow::Cow;
use std::cmp::Ordering;
use std::ops::{Add, Sub};
use std::str::FromStr;
use std::{fmt, net};

use chrono::{DateTime, Datelike, Duration, LocalResult, NaiveDateTime, TimeZone, Utc};
use enumset::EnumSet;
use relay_protocol::{
    Annotated, Array, Empty, Error, ErrorKind, FromValue, IntoValue, Meta, Object,
    SkipSerialization, Value,
};
use serde::{Deserialize, Deserializer, Serialize, Serializer};

use crate::processor::{
    process_value, ProcessValue, ProcessingResult, ProcessingState, Processor, ValueType,
};

/// An array-like wrapper used in various places.
#[derive(Clone, Debug, PartialEq, Empty, IntoValue, ProcessValue)]
#[metastructure(process_func = "process_values")]
pub struct Values<T> {
    /// The values of the collection.
    #[metastructure(required = "true", skip_serialization = "empty_deep")]
    pub values: Annotated<Array<T>>,

    /// Additional arbitrary fields for forwards compatibility.
    #[metastructure(additional_properties)]
    pub other: Object<Value>,
}

impl<T> Default for Values<T> {
    fn default() -> Values<T> {
        // Default implemented manually even if <T> does not impl Default.
        Values::new(Vec::new())
    }
}

impl<T> Values<T> {
    /// Constructs a new value array from a given array
    pub fn new(values: Array<T>) -> Values<T> {
        Values {
            values: Annotated::new(values),
            other: Object::default(),
        }
    }
}

impl<T: FromValue> FromValue for Values<T> {
    fn from_value(value: Annotated<Value>) -> Annotated<Self> {
        match value {
            // Example:
            // {"threads": [foo, bar, baz]}
            Annotated(Some(Value::Array(items)), meta) => Annotated(
                Some(Values {
                    values: Annotated(
                        Some(items.into_iter().map(FromValue::from_value).collect()),
                        meta,
                    ),
                    other: Object::new(),
                }),
                Meta::default(),
            ),
            Annotated(Some(Value::Object(mut obj)), meta) => {
                if obj.is_empty() {
                    // Example:
                    // {"exception": {}}
                    // {"threads": {}}
                    Annotated(None, meta)
                } else if let Some(values) = obj.remove("values") {
                    // Example:
                    // {"exception": {"values": [foo, bar, baz]}}
                    Annotated(
                        Some(Values {
                            values: FromValue::from_value(values),
                            other: obj,
                        }),
                        meta,
                    )
                } else {
                    // Example:
                    // {"exception": {"type": "ZeroDivisonError"}
                    Annotated(
                        Some(Values {
                            values: Annotated(
                                Some(vec![FromValue::from_value(Annotated(
                                    Some(Value::Object(obj)),
                                    meta,
                                ))]),
                                Meta::default(),
                            ),
                            other: Object::new(),
                        }),
                        Meta::default(),
                    )
                }
            }
            Annotated(None, meta) => Annotated(None, meta),
            Annotated(Some(value), mut meta) => {
                meta.add_error(Error::expected("a list or values object"));
                meta.set_original_value(Some(value));
                Annotated(None, meta)
            }
        }
    }
}

/// A trait to abstract over pairs.
pub trait AsPair {
    type Key: AsRef<str>;
    type Value: ProcessValue;

    /// Constructs this value from a raw tuple.
    fn from_pair(pair: (Annotated<Self::Key>, Annotated<Self::Value>)) -> Self;

    /// Converts this pair into a raw tuple.
    fn into_pair(self) -> (Annotated<Self::Key>, Annotated<Self::Value>);

    /// Extracts a key and value pair from the object.
    fn as_pair(&self) -> (&Annotated<Self::Key>, &Annotated<Self::Value>);

    /// Extracts the mutable key and value pair from the object.
    fn as_pair_mut(&mut self) -> (&mut Annotated<Self::Key>, &mut Annotated<Self::Value>);

    /// Returns a reference to the string representation of the key.
    fn key(&self) -> Option<&str> {
        self.as_pair().0.as_str()
    }

    /// Returns a reference to the value.
    fn value(&self) -> Option<&Self::Value> {
        self.as_pair().1.value()
    }
}

impl<K, V> AsPair for (Annotated<K>, Annotated<V>)
where
    K: AsRef<str>,
    V: ProcessValue,
{
    type Key = K;
    type Value = V;

    fn from_pair(pair: (Annotated<Self::Key>, Annotated<Self::Value>)) -> Self {
        pair
    }

    fn into_pair(self) -> (Annotated<Self::Key>, Annotated<Self::Value>) {
        self
    }

    fn as_pair(&self) -> (&Annotated<Self::Key>, &Annotated<Self::Value>) {
        (&self.0, &self.1)
    }

    fn as_pair_mut(&mut self) -> (&mut Annotated<Self::Key>, &mut Annotated<Self::Value>) {
        (&mut self.0, &mut self.1)
    }
}

/// A mixture of a hashmap and an array.
#[derive(Clone, Debug, Default, PartialEq, Empty, IntoValue)]
pub struct PairList<T>(pub Array<T>);

impl<T, K, V> PairList<T>
where
    K: AsRef<str>,
    V: ProcessValue,
    T: AsPair<Key = K, Value = V>,
{
    /// Searches for an entry with the given key and returns its position.
    pub fn position<Q>(&self, key: Q) -> Option<usize>
    where
        Q: AsRef<str>,
    {
        let key = key.as_ref();
        self.0
            .iter()
            .filter_map(Annotated::value)
            .position(|entry| entry.as_pair().0.as_str() == Some(key))
    }

    /// Returns a reference to the annotated value corresponding to the key.
    ///
    /// The key may be any borrowed form of the pairlist's key type. If there are multiple entries
    /// with the same key, the first is returned.
    pub fn get<'a, Q>(&'a self, key: Q) -> Option<&Annotated<V>>
    where
        Q: AsRef<str>,
        K: 'a,
    {
        self.position(key)
            .and_then(|pos| self.0.get(pos))
            .and_then(Annotated::value)
            .map(|pair| pair.as_pair().1)
    }

    /// Returns a reference to the value corresponding to the key.
    ///
    /// The key may be any borrowed form of the pairlist's key type. If there are multiple entries
    /// with the same key, the first is returned.
    pub fn get_value<'a, Q>(&'a self, key: Q) -> Option<&V>
    where
        Q: AsRef<str>,
        K: 'a,
    {
        self.get(key).and_then(Annotated::value)
    }

    /// Returns `true` if the pair list contains a value for the specified key.
    pub fn contains<Q>(&self, key: Q) -> bool
    where
        Q: AsRef<str>,
    {
        self.position(key).is_some()
    }

    /// Removes an entry matching the given key and returns its value, if found.
    pub fn remove<Q>(&mut self, key: Q) -> Option<Annotated<V>>
    where
        Q: AsRef<str>,
    {
        self.position(key)
            .and_then(|index| self.0.remove(index).0)
            .map(|entry| entry.into_pair().1)
    }

    /// Inserts a value into the list and returns the old value.
    pub fn insert(&mut self, key: K, value: Annotated<V>) -> Option<Annotated<V>> {
        match self.position(key.as_ref()) {
            Some(index) => self
                .get_mut(index)
                .and_then(|annotated| annotated.value_mut().as_mut())
                .map(|pair| std::mem::replace(pair.as_pair_mut().1, value)),
            None => {
                self.push(Annotated::new(T::from_pair((Annotated::new(key), value))));
                None
            }
        }
    }
}

impl<T> std::ops::Deref for PairList<T> {
    type Target = Array<T>;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl<T> std::ops::DerefMut for PairList<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}

impl<A> FromIterator<Annotated<A>> for PairList<A> {
    fn from_iter<T>(iter: T) -> Self
    where
        T: IntoIterator<Item = Annotated<A>>,
    {
        PairList(FromIterator::from_iter(iter))
    }
}

impl<T> From<Array<T>> for PairList<T> {
    fn from(value: Array<T>) -> Self {
        PairList(value)
    }
}

impl<T: FromValue> FromValue for PairList<T> {
    fn from_value(value: Annotated<Value>) -> Annotated<Self> {
        match value {
            Annotated(Some(Value::Array(items)), meta) => {
                let mut rv = Vec::new();
                for item in items.into_iter() {
                    rv.push(T::from_value(item));
                }
                Annotated(Some(PairList(rv)), meta)
            }
            Annotated(Some(Value::Object(items)), meta) => {
                let mut rv = Vec::new();
                for (key, value) in items.into_iter() {
                    rv.push(T::from_value(Annotated::new(Value::Array(vec![
                        Annotated::new(Value::String(key)),
                        value,
                    ]))));
                }
                Annotated(Some(PairList(rv)), meta)
            }
            other => FromValue::from_value(other).map_value(PairList),
        }
    }
}

impl<T> ProcessValue for PairList<T>
where
    T: ProcessValue + AsPair,
{
    #[inline]
    fn value_type(&self) -> EnumSet<ValueType> {
        EnumSet::only(ValueType::Object)
    }

    #[inline]
    fn process_value<P>(
        &mut self,
        meta: &mut Meta,
        processor: &mut P,
        state: &ProcessingState<'_>,
    ) -> ProcessingResult
    where
        P: Processor,
    {
        processor.process_pairlist(self, meta, state)
    }

    fn process_child_values<P>(
        &mut self,
        processor: &mut P,
        state: &ProcessingState<'_>,
    ) -> ProcessingResult
    where
        P: Processor,
    {
        for (idx, pair) in self.0.iter_mut().enumerate() {
            let state = state.enter_index(idx, state.inner_attrs(), ValueType::for_field(pair));
            process_value(pair, processor, &state)?;
        }

        Ok(())
    }
}

macro_rules! hex_metrastructure {
    ($type:ident, $expectation:expr) => {
        impl FromStr for $type {
            type Err = std::num::ParseIntError;

            fn from_str(s: &str) -> Result<$type, Self::Err> {
                if s.starts_with("0x") || s.starts_with("0X") {
                    u64::from_str_radix(&s[2..], 16).map($type)
                } else {
                    s.parse().map($type)
                }
            }
        }

        impl fmt::Display for $type {
            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                write!(f, "{:#x}", self.0)
            }
        }

        impl Empty for $type {
            #[inline]
            fn is_empty(&self) -> bool {
                false
            }
        }

        impl FromValue for $type {
            fn from_value(value: Annotated<Value>) -> Annotated<Self> {
                match value {
                    Annotated(Some(Value::String(value)), mut meta) => match value.parse() {
                        Ok(value) => Annotated(Some(value), meta),
                        Err(err) => {
                            meta.add_error(Error::invalid(err));
                            meta.set_original_value(Some(value));
                            Annotated(None, meta)
                        }
                    },
                    Annotated(Some(Value::U64(value)), meta) => Annotated(Some($type(value)), meta),
                    Annotated(Some(Value::I64(value)), meta) => {
                        Annotated(Some($type(value as u64)), meta)
                    }
                    Annotated(None, meta) => Annotated(None, meta),
                    Annotated(Some(value), mut meta) => {
                        meta.add_error(Error::expected($expectation));
                        meta.set_original_value(Some(value));
                        Annotated(None, meta)
                    }
                }
            }
        }

        impl IntoValue for $type {
            fn into_value(self) -> Value {
                Value::String(self.to_string())
            }
            fn serialize_payload<S>(
                &self,
                s: S,
                _behavior: relay_protocol::SkipSerialization,
            ) -> Result<S::Ok, S::Error>
            where
                Self: Sized,
                S: Serializer,
            {
                Serializer::collect_str(s, self)
            }
        }

        impl ProcessValue for $type {}
    };
}

/// Raised if a register value can't be parsed.
#[derive(Debug)]
pub struct InvalidRegVal;

impl fmt::Display for InvalidRegVal {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "invalid register value")
    }
}

impl std::error::Error for InvalidRegVal {}

/// A register value.
#[derive(Default, Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct RegVal(pub u64);

hex_metrastructure!(RegVal, "register value");

/// An address
#[derive(Default, Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Addr(pub u64);

hex_metrastructure!(Addr, "address");
relay_common::impl_str_serde!(Addr, "an address");

/// An ip address.
#[derive(
    Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, Empty, IntoValue, ProcessValue, Serialize,
)]
pub struct IpAddr(pub String);

impl IpAddr {
    /// Returns the auto marker ip address.
    pub fn auto() -> IpAddr {
        IpAddr("{{auto}}".into())
    }

    /// Parses an `IpAddr` from a string
    pub fn parse<S>(value: S) -> Result<Self, S>
    where
        S: AsRef<str> + Into<String>,
    {
        if value.as_ref() == "{{auto}}" {
            return Ok(IpAddr(value.into()));
        }

        match net::IpAddr::from_str(value.as_ref()) {
            Ok(_) => Ok(IpAddr(value.into())),
            Err(_) => Err(value),
        }
    }

    /// Checks if the ip address is set to the auto marker.
    pub fn is_auto(&self) -> bool {
        self.0 == "{{auto}}"
    }

    /// Checks whether the contained ip address is still valid (relevant for PII processing).
    pub fn is_valid(&self) -> bool {
        self.is_auto() || net::IpAddr::from_str(&self.0).is_ok()
    }

    /// Returns the string value of this ip address.
    pub fn as_str(&self) -> &str {
        &self.0
    }

    /// Convert IP address into owned string.
    pub fn into_inner(self) -> String {
        self.0
    }
}

impl AsRef<str> for IpAddr {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

impl Default for IpAddr {
    fn default() -> Self {
        IpAddr::auto()
    }
}

impl From<std::net::IpAddr> for IpAddr {
    fn from(ip_addr: std::net::IpAddr) -> Self {
        Self(ip_addr.to_string())
    }
}

impl fmt::Display for IpAddr {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl<'de> Deserialize<'de> for IpAddr {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        let string = Cow::<'_, str>::deserialize(deserializer)?;
        IpAddr::parse(string).map_err(|_| serde::de::Error::custom("expected an ip address"))
    }
}

impl FromValue for IpAddr {
    fn from_value(value: Annotated<Value>) -> Annotated<Self> {
        match value {
            Annotated(Some(Value::String(value)), mut meta) => match IpAddr::parse(value) {
                Ok(addr) => Annotated(Some(addr), meta),
                Err(value) => {
                    meta.add_error(Error::expected("an ip address"));
                    meta.set_original_value(Some(value));
                    Annotated(None, meta)
                }
            },
            Annotated(None, meta) => Annotated(None, meta),
            Annotated(Some(value), mut meta) => {
                meta.add_error(Error::expected("an ip address"));
                meta.set_original_value(Some(value));
                Annotated(None, meta)
            }
        }
    }
}

impl FromStr for IpAddr {
    type Err = ();

    fn from_str(value: &str) -> Result<Self, Self::Err> {
        IpAddr::parse(value).map_err(|_| ())
    }
}

/// An error used when parsing `Level`.
#[derive(Debug)]
pub struct ParseLevelError;

impl fmt::Display for ParseLevelError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "invalid level")
    }
}

impl std::error::Error for ParseLevelError {}

/// Severity level of an event or breadcrumb.
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
pub enum Level {
    /// Indicates very spammy debug information.
    Debug,
    /// Informational messages.
    #[default]
    Info,
    /// A warning.
    Warning,
    /// An error.
    Error,
    /// Similar to error but indicates a critical event that usually causes a shutdown.
    Fatal,
}

impl Level {
    pub fn name(self) -> &'static str {
        match self {
            Level::Debug => "debug",
            Level::Info => "info",
            Level::Warning => "warning",
            Level::Error => "error",
            Level::Fatal => "fatal",
        }
    }

    fn from_python_level(value: u64) -> Option<Level> {
        Some(match value {
            10 => Level::Debug,
            20 => Level::Info,
            30 => Level::Warning,
            40 => Level::Error,
            50 => Level::Fatal,
            _ => return None,
        })
    }
}

impl FromStr for Level {
    type Err = ParseLevelError;

    fn from_str(string: &str) -> Result<Self, Self::Err> {
        Ok(match string {
            "debug" => Level::Debug,
            "info" | "log" => Level::Info,
            "warning" => Level::Warning,
            "error" => Level::Error,
            "fatal" | "critical" => Level::Fatal,
            _ => return Err(ParseLevelError),
        })
    }
}

impl fmt::Display for Level {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(self.name())
    }
}

impl FromValue for Level {
    fn from_value(value: Annotated<Value>) -> Annotated<Self> {
        match value {
            Annotated(Some(Value::String(value)), mut meta) => match value.parse() {
                Ok(value) => Annotated(Some(value), meta),
                Err(err) => {
                    meta.add_error(Error::invalid(err));
                    meta.set_original_value(Some(value));
                    Annotated(None, meta)
                }
            },
            Annotated(Some(Value::U64(val)), mut meta) => match Level::from_python_level(val) {
                Some(value) => Annotated(Some(value), meta),
                None => {
                    meta.add_error(ErrorKind::InvalidData);
                    meta.set_original_value(Some(val));
                    Annotated(None, meta)
                }
            },
            Annotated(Some(Value::I64(val)), mut meta) => {
                match Level::from_python_level(val as u64) {
                    Some(value) => Annotated(Some(value), meta),
                    None => {
                        meta.add_error(ErrorKind::InvalidData);
                        meta.set_original_value(Some(val));
                        Annotated(None, meta)
                    }
                }
            }
            Annotated(None, meta) => Annotated(None, meta),
            Annotated(Some(value), mut meta) => {
                meta.add_error(Error::expected("a level"));
                meta.set_original_value(Some(value));
                Annotated(None, meta)
            }
        }
    }
}

impl IntoValue for Level {
    fn into_value(self) -> Value {
        Value::String(self.to_string())
    }

    fn serialize_payload<S>(&self, s: S, _behavior: SkipSerialization) -> Result<S::Ok, S::Error>
    where
        Self: Sized,
        S: Serializer,
    {
        Serialize::serialize(self.name(), s)
    }
}

impl ProcessValue for Level {}

impl Empty for Level {
    #[inline]
    fn is_empty(&self) -> bool {
        false
    }
}

/// A "into-string" type of value. Emulates an invocation of `str(x)` in Python
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Empty, IntoValue, ProcessValue)]
pub struct LenientString(pub String);

impl LenientString {
    /// Returns the string value.
    pub fn as_str(&self) -> &str {
        &self.0
    }

    /// Unwraps the inner raw string.
    pub fn into_inner(self) -> String {
        self.0
    }
}

impl AsRef<str> for LenientString {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

impl std::ops::Deref for LenientString {
    type Target = String;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl std::ops::DerefMut for LenientString {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}

impl From<String> for LenientString {
    fn from(value: String) -> Self {
        LenientString(value)
    }
}

impl FromValue for LenientString {
    fn from_value(value: Annotated<Value>) -> Annotated<Self> {
        match value {
            Annotated(Some(Value::String(string)), meta) => Annotated(Some(string), meta),
            // XXX: True/False instead of true/false because of old python code
            Annotated(Some(Value::Bool(true)), meta) => Annotated(Some("True".to_string()), meta),
            Annotated(Some(Value::Bool(false)), meta) => Annotated(Some("False".to_string()), meta),
            Annotated(Some(Value::U64(num)), meta) => Annotated(Some(num.to_string()), meta),
            Annotated(Some(Value::I64(num)), meta) => Annotated(Some(num.to_string()), meta),
            Annotated(Some(Value::F64(num)), mut meta) => {
                if num.abs() < (1i64 << 53) as f64 {
                    Annotated(Some(num.trunc().to_string()), meta)
                } else {
                    meta.add_error(Error::expected("a number with JSON precision"));
                    meta.set_original_value(Some(num));
                    Annotated(None, meta)
                }
            }
            Annotated(None, meta) => Annotated(None, meta),
            Annotated(Some(value), mut meta) => {
                meta.add_error(Error::expected("a primitive value"));
                meta.set_original_value(Some(value));
                Annotated(None, meta)
            }
        }
        .map_value(LenientString)
    }
}

/// A "into-string" type of value. All non-string values are serialized as JSON.
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Empty, IntoValue, ProcessValue)]
pub struct JsonLenientString(pub String);

impl JsonLenientString {
    /// Returns the string value.
    pub fn as_str(&self) -> &str {
        &self.0
    }

    /// Unwraps the inner raw string.
    pub fn into_inner(self) -> String {
        self.0
    }
}

impl AsRef<str> for JsonLenientString {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

impl std::ops::Deref for JsonLenientString {
    type Target = String;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl std::ops::DerefMut for JsonLenientString {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}

impl From<JsonLenientString> for String {
    fn from(value: JsonLenientString) -> Self {
        value.0
    }
}

impl FromValue for JsonLenientString {
    fn from_value(value: Annotated<Value>) -> Annotated<Self> {
        match value {
            Annotated(Some(Value::String(string)), meta) => Annotated(Some(string.into()), meta),
            Annotated(Some(other), meta) => {
                Annotated(Some(serde_json::to_string(&other).unwrap().into()), meta)
            }
            Annotated(None, meta) => Annotated(None, meta),
        }
    }
}

impl From<String> for JsonLenientString {
    fn from(value: String) -> Self {
        JsonLenientString(value)
    }
}

#[derive(Clone, Copy, Debug, Eq, PartialEq, Ord, PartialOrd)]
pub struct Timestamp(pub DateTime<Utc>);

impl Timestamp {
    pub fn into_inner(self) -> DateTime<Utc> {
        self.0
    }
}

impl ProcessValue for Timestamp {
    #[inline]
    fn value_type(&self) -> EnumSet<ValueType> {
        EnumSet::only(ValueType::DateTime)
    }

    #[inline]
    fn process_value<P>(
        &mut self,
        meta: &mut Meta,
        processor: &mut P,
        state: &ProcessingState<'_>,
    ) -> ProcessingResult
    where
        P: Processor,
    {
        processor.process_timestamp(self, meta, state)
    }
}

impl From<DateTime<Utc>> for Timestamp {
    fn from(value: DateTime<Utc>) -> Self {
        Timestamp(value)
    }
}

impl Add<Duration> for Timestamp {
    type Output = Self;

    fn add(self, duration: Duration) -> Self::Output {
        Timestamp(self.0 + duration)
    }
}

impl Sub<Timestamp> for Timestamp {
    type Output = chrono::Duration;

    fn sub(self, rhs: Timestamp) -> Self::Output {
        self.into_inner() - rhs.into_inner()
    }
}

impl PartialEq<DateTime<Utc>> for Timestamp {
    fn eq(&self, other: &DateTime<Utc>) -> bool {
        &self.0 == other
    }
}

impl PartialOrd<DateTime<Utc>> for Timestamp {
    fn partial_cmp(&self, other: &DateTime<Utc>) -> Option<Ordering> {
        self.0.partial_cmp(other)
    }
}

impl fmt::Display for Timestamp {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

pub fn datetime_to_timestamp(dt: DateTime<Utc>) -> f64 {
    // f64s cannot store nanoseconds. To verify this just try to fit the current timestamp in
    // nanoseconds into a 52-bit number (which is the significand of a double).
    //
    // Round off to microseconds to not show more decimal points than we know are correct. Anything
    // else might trick the user into thinking the nanoseconds in those timestamps mean anything.
    //
    // This needs to be done regardless of whether the input value was a ISO-formatted string or a
    // number because it all ends up as a f64 on serialization.
    //
    // If we want to support nanoseconds at some point we will probably have to start using strings
    // everywhere. Even then it's unclear how to deal with it in Python code as a `datetime` cannot
    // store nanoseconds.
    //
    // We use `timestamp_subsec_nanos` instead of `timestamp_subsec_micros` anyway to get better
    // rounding behavior.
    let micros = (f64::from(dt.timestamp_subsec_nanos()) / 1_000f64).round();
    dt.timestamp() as f64 + (micros / 1_000_000f64)
}

fn utc_result_to_annotated<V: IntoValue>(
    result: LocalResult<DateTime<Utc>>,
    original_value: V,
    mut meta: Meta,
) -> Annotated<DateTime<Utc>> {
    match result {
        LocalResult::Single(value) => Annotated(Some(value), meta),
        LocalResult::Ambiguous(_, _) => {
            meta.add_error(Error::expected("ambiguous timestamp"));
            meta.set_original_value(Some(original_value));
            Annotated(None, meta)
        }
        LocalResult::None => {
            meta.add_error(Error::invalid("timestamp out of range"));
            meta.set_original_value(Some(original_value));
            Annotated(None, meta)
        }
    }
}

impl FromValue for Timestamp {
    fn from_value(value: Annotated<Value>) -> Annotated<Self> {
        let rv = match value {
            Annotated(Some(Value::String(value)), mut meta) => {
                // NaiveDateTime parses "%Y-%m-%dT%H:%M:%S%.f"
                let parsed = match value.parse::<NaiveDateTime>() {
                    Ok(dt) => Ok(DateTime::from_naive_utc_and_offset(dt, Utc)),

                    // XXX: This actually accepts more than RFC 3339. SDKs are strongly discouraged
                    // from exercising that freedom. We should only support RFC3339.
                    //
                    // See https://github.com/chronotope/chrono/pull/516 (docs PR) for what this
                    // actually does: It appears to accept a superset of RFC3339, but only a subset
                    // of ISO 8601.
                    Err(_) => value.parse(),
                };
                match parsed {
                    Ok(value) => Annotated(Some(value), meta),
                    Err(err) => {
                        meta.add_error(Error::invalid(err));
                        meta.set_original_value(Some(value));
                        Annotated(None, meta)
                    }
                }
            }
            Annotated(Some(Value::U64(ts)), meta) => {
                utc_result_to_annotated(Utc.timestamp_opt(ts as i64, 0), ts, meta)
            }
            Annotated(Some(Value::I64(ts)), meta) => {
                utc_result_to_annotated(Utc.timestamp_opt(ts, 0), ts, meta)
            }
            Annotated(Some(Value::F64(ts)), meta) => {
                let secs = ts as i64;
                // at this point we probably already lose nanosecond precision, but we deal with
                // this in `datetime_to_timestamp`.
                let nanos = (ts.fract() * 1_000_000_000f64) as u32;
                utc_result_to_annotated(Utc.timestamp_opt(secs, nanos), ts, meta)
            }
            Annotated(None, meta) => Annotated(None, meta),
            Annotated(Some(value), mut meta) => {
                meta.add_error(Error::expected("a timestamp"));
                meta.set_original_value(Some(value));
                Annotated(None, meta)
            }
        };

        match rv {
            Annotated(Some(value), mut meta) => {
                if value.year() > 9999 {
                    // We need to enforce this because Python has a max value for year and
                    // otherwise crashes. Also this is probably nicer UX than silently showing the
                    // wrong value.
                    meta.add_error(Error::invalid("timestamp out of range"));
                    meta.set_original_value(Some(Timestamp(value)));
                    Annotated(None, meta)
                } else {
                    Annotated(Some(Timestamp(value)), meta)
                }
            }
            x => x.map_value(Timestamp),
        }
    }
}

impl IntoValue for Timestamp {
    fn into_value(self) -> Value {
        Value::F64(datetime_to_timestamp(self.0))
    }

    fn serialize_payload<S>(&self, s: S, _behavior: SkipSerialization) -> Result<S::Ok, S::Error>
    where
        Self: Sized,
        S: Serializer,
    {
        Serialize::serialize(&datetime_to_timestamp(self.0), s)
    }
}

impl Empty for Timestamp {
    fn is_empty(&self) -> bool {
        false
    }
}

#[cfg(test)]
mod tests {
    use similar_asserts::assert_eq;

    use super::*;

    #[test]
    fn test_values_serialization() {
        let value = Annotated::new(Values {
            values: Annotated::new(vec![
                Annotated::new(0u64),
                Annotated::new(1u64),
                Annotated::new(2u64),
            ]),
            other: Object::default(),
        });
        assert_eq!(value.to_json().unwrap(), "{\"values\":[0,1,2]}");
    }

    #[test]
    fn test_values_deserialization() {
        #[derive(Clone, Debug, Empty, FromValue, IntoValue, PartialEq)]
        struct Exception {
            #[metastructure(field = "type")]
            ty: Annotated<String>,
            value: Annotated<String>,
        }
        let value = Annotated::<Values<Exception>>::from_json(
            r#"{"values": [{"type": "Test", "value": "aha!"}]}"#,
        )
        .unwrap();
        assert_eq!(
            value,
            Annotated::new(Values::new(vec![Annotated::new(Exception {
                ty: Annotated::new("Test".to_string()),
                value: Annotated::new("aha!".to_string()),
            })]))
        );

        let value =
            Annotated::<Values<Exception>>::from_json(r#"[{"type": "Test", "value": "aha!"}]"#)
                .unwrap();
        assert_eq!(
            value,
            Annotated::new(Values::new(vec![Annotated::new(Exception {
                ty: Annotated::new("Test".to_string()),
                value: Annotated::new("aha!".to_string()),
            })]))
        );

        let value =
            Annotated::<Values<Exception>>::from_json(r#"{"type": "Test", "value": "aha!"}"#)
                .unwrap();
        assert_eq!(
            value,
            Annotated::new(Values::new(vec![Annotated::new(Exception {
                ty: Annotated::new("Test".to_string()),
                value: Annotated::new("aha!".to_string()),
            })]))
        );
    }

    #[test]
    fn test_hex_to_string() {
        assert_eq!("0x0", &Addr(0).to_string());
        assert_eq!("0x2a", &Addr(42).to_string());
    }

    #[test]
    fn test_hex_from_string() {
        assert_eq!(Addr(0), "0".parse().unwrap());
        assert_eq!(Addr(42), "42".parse().unwrap());
        assert_eq!(Addr(42), "0x2a".parse().unwrap());
        assert_eq!(Addr(42), "0X2A".parse().unwrap());
    }

    #[test]
    fn test_hex_serialization() {
        let value = Value::String("0x2a".to_string());
        let addr: Annotated<Addr> = FromValue::from_value(Annotated::new(value));
        assert_eq!(addr.payload_to_json().unwrap(), "\"0x2a\"");
        let value = Value::U64(42);
        let addr: Annotated<Addr> = FromValue::from_value(Annotated::new(value));
        assert_eq!(addr.payload_to_json().unwrap(), "\"0x2a\"");
    }

    #[test]
    fn test_hex_deserialization() {
        let addr = Annotated::<Addr>::from_json("\"0x2a\"").unwrap();
        assert_eq!(addr.payload_to_json().unwrap(), "\"0x2a\"");
        let addr = Annotated::<Addr>::from_json("42").unwrap();
        assert_eq!(addr.payload_to_json().unwrap(), "\"0x2a\"");
    }

    #[test]
    fn test_level() {
        assert_eq!(
            Level::Info,
            Annotated::<Level>::from_json("\"log\"").unwrap().0.unwrap()
        );
        assert_eq!(
            Level::Warning,
            Annotated::<Level>::from_json("30").unwrap().0.unwrap()
        );
        assert_eq!(
            Level::Fatal,
            Annotated::<Level>::from_json("\"critical\"")
                .unwrap()
                .0
                .unwrap()
        );
    }

    #[test]
    fn test_ip_addr() {
        assert_eq!(
            IpAddr("{{auto}}".into()),
            Annotated::<IpAddr>::from_json("\"{{auto}}\"")
                .unwrap()
                .0
                .unwrap()
        );
        assert_eq!(
            IpAddr("127.0.0.1".into()),
            Annotated::<IpAddr>::from_json("\"127.0.0.1\"")
                .unwrap()
                .0
                .unwrap()
        );
        assert_eq!(
            IpAddr("::1".into()),
            Annotated::<IpAddr>::from_json("\"::1\"")
                .unwrap()
                .0
                .unwrap()
        );
        assert_eq!(
            Annotated::from_error(
                Error::expected("an ip address"),
                Some(Value::String("clearly invalid value".into()))
            ),
            Annotated::<IpAddr>::from_json("\"clearly invalid value\"").unwrap()
        );
    }

    #[test]
    fn test_timestamp_year_out_of_range() {
        #[derive(Debug, FromValue, Default, Empty, IntoValue)]
        struct Helper {
            foo: Annotated<Timestamp>,
        }

        let x: Annotated<Helper> = Annotated::from_json(r#"{"foo": 1562770897893}"#).unwrap();
        assert_eq!(
            x.to_json_pretty().unwrap(),
            r#"{
  "foo": null,
  "_meta": {
    "foo": {
      "": {
        "err": [
          [
            "invalid_data",
            {
              "reason": "timestamp out of range"
            }
          ]
        ],
        "val": 1562770897893.0
      }
    }
  }
}"#
        );
    }

    #[test]
    fn test_timestamp_completely_out_of_range() {
        #[derive(Debug, FromValue, Default, Empty, IntoValue)]
        struct Helper {
            foo: Annotated<Timestamp>,
        }

        let x: Annotated<Helper> =
            Annotated::from_json(r#"{"foo": -10000000000000000.0}"#).unwrap();
        assert_eq!(
            x.to_json_pretty().unwrap(),
            r#"{
  "foo": null,
  "_meta": {
    "foo": {
      "": {
        "err": [
          [
            "invalid_data",
            {
              "reason": "timestamp out of range"
            }
          ]
        ],
        "val": -1e16
      }
    }
  }
}"#
        );
    }
}