/*
 * vSMTP mail transfer agent
 * Copyright (C) 2022 viridIT SAS
 *
 * 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 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/.
 *
*/

use rhai::plugin::{
    mem, Dynamic, FnAccess, FnNamespace, ImmutableString, NativeCallContext, PluginFunction,
    RhaiResult, TypeId,
};
use rhai::Module;

use std::str::FromStr;

/// Objects are rust's representation of rule engine variables.
/// multiple types are supported.
///
/// NOTE: Objects are represented as an enum because it is easier to create containers
/// for them.
#[derive(Debug, Clone, strum::AsRefStr)]
#[strum(serialize_all = "lowercase")]
pub enum Object {
    /// ip v4 address. (a.b.c.d)
    Ip4(std::net::Ipv4Addr),
    /// ip v6 address. (x:x:x:x:x:x:x:x)
    Ip6(std::net::Ipv6Addr),
    /// an ip v4 range. (a.b.c.d/range)
    Rg4(iprange::IpRange<ipnet::Ipv4Net>),
    /// an ip v6 range. (x:x:x:x:x:x:x:x/range)
    Rg6(iprange::IpRange<ipnet::Ipv6Net>),
    /// an email address (jones@foo.com)
    Address(vsmtp_common::Address),
    /// a valid fully qualified domain name (foo.com)
    Fqdn(String),
    /// a regex (^[a-z0-9.]+@foo.com$)
    Regex(regex::Regex),
    /// a user identifier.
    Identifier(String),
    /// a custom smtp reply code.
    Code(vsmtp_common::Reply),
}

/// A ``vSL`` object that is shared or not, depending of the context of the rule engine.
pub type SharedObject = rhai::Shared<Object>;

/// Create a new object using the [`FromStr`] trait.
macro_rules! new_object_from_str {
    ($value:expr, $type:ty, $object_type:expr) => {
        <$type as std::str::FromStr>::from_str($value)
            .map(|value| $object_type(value))
            .map_err(|err| anyhow::anyhow!("{err}"))
    };
}

impl Object {
    fn from_str(s: &str, value: &str) -> anyhow::Result<Self> {
        match s {
            "ip4" => Self::new_ip4(value),
            "ip6" => Self::new_ip6(value),
            "rg4" => Self::new_rg4(value),
            "rg6" => Self::new_rg6(value),
            "address" => Self::new_address(value),
            "fqdn" => Self::new_fqdn(value),
            "regex" => Self::new_regex(value),
            "identifier" => Ok(Self::new_identifier(value)),

            // "file" => Ok(Self::new_file(value)),
            // "code" => Ok(()),
            _ => Err(anyhow::anyhow!("invalid object type: {}", s)),
        }
    }

    /// Create a new ip v4 object.
    ///
    /// # Errors
    /// * The value could not be converted.
    pub fn new_ip4(ip: impl AsRef<str>) -> anyhow::Result<Object> {
        new_object_from_str!(ip.as_ref(), std::net::Ipv4Addr, Object::Ip4)
    }

    /// Create a new ip v6 object.
    ///
    /// # Errors
    /// * The value could not be converted.
    pub fn new_ip6(ip: impl AsRef<str>) -> anyhow::Result<Object> {
        new_object_from_str!(ip.as_ref(), std::net::Ipv6Addr, Object::Ip6)
    }

    /// Create a new ip v4 range object.
    ///
    /// # Errors
    /// * The value could not be converted.
    pub fn new_rg4(range: impl AsRef<str>) -> anyhow::Result<Object> {
        range
            .as_ref()
            .parse::<ipnet::Ipv4Net>()
            .map(|range| Object::Rg4(std::iter::once(range).collect()))
            .map_err(|error| anyhow::anyhow!("{error}"))
    }

    /// Create a new ip v6 range object.
    ///
    /// # Errors
    /// * The value could not be converted.
    pub fn new_rg6(range: impl AsRef<str>) -> anyhow::Result<Object> {
        range
            .as_ref()
            .parse::<ipnet::Ipv6Net>()
            .map(|range| Object::Rg6(std::iter::once(range).collect()))
            .map_err(|error| anyhow::anyhow!("{error}"))
    }

    /// Create a new address object.
    ///
    /// # Errors
    /// * The value could not be converted.
    pub fn new_address(address: impl AsRef<str>) -> anyhow::Result<Object> {
        new_object_from_str!(address.as_ref(), vsmtp_common::Address, Object::Address)
    }

    /// Create a new full qualified domain name object.
    ///
    /// # Errors
    /// * The value could not be converted.

    pub fn new_fqdn(domain: impl AsRef<str>) -> anyhow::Result<Object> {
        addr::parse_domain_name(domain.as_ref())
            .map(|domain| Object::Fqdn(domain.to_string()))
            .map_err(|error| anyhow::anyhow!("{error}"))
    }

    /// Create a new regex object.
    ///
    /// # Errors
    /// * The value could not be converted.
    pub fn new_regex(regex: impl AsRef<str>) -> anyhow::Result<Object> {
        new_object_from_str!(regex.as_ref(), regex::Regex, Object::Regex)
    }

    /// Create a new file object.
    ///
    /// # Errors
    /// * The value could not be converted.
    pub fn new_file(
        path: impl AsRef<std::path::Path>,
        content_type: impl AsRef<str>,
    ) -> anyhow::Result<rhai::Array> {
        std::fs::read_to_string(path.as_ref())?
            .lines()
            .map(str::trim)
            .filter(|line| !line.is_empty())
            .map(|line| Self::from_str(content_type.as_ref(), line).map(rhai::Dynamic::from))
            .collect::<anyhow::Result<rhai::Array>>()
    }

    /// Create a new identifier object.
    pub fn new_identifier(identifier: impl Into<String>) -> Object {
        Object::Identifier(identifier.into())
    }

    /// Create a new code object.
    pub fn new_code(code: u16, text: impl Into<String>) -> Object {
        Object::Code(
            format!("{code} {}", text.into())
                .parse::<vsmtp_common::Reply>()
                .unwrap(),
        )
    }

    /// Create a new code object with an enhanced code.
    pub fn new_code_enhanced<T>(code: u16, enhanced: T, text: T) -> Object
    where
        T: Into<String>,
    {
        Object::Code(
            format!("{code} {} {}", enhanced.into(), text.into())
                .parse::<vsmtp_common::Reply>()
                .unwrap(),
        )
    }
}

impl Object {
    /// check if the `other` object is contained in this object,
    /// return false automatically if the item cannot be contained in this object.
    #[must_use]
    pub fn contains(&self, other: &Self) -> bool {
        match (self, other) {
            (Object::Rg4(rg4), Object::Ip4(ip4)) => rg4.contains(ip4),
            (Object::Rg6(rg6), Object::Ip6(ip6)) => rg6.contains(ip6),
            (Object::Regex(regex), other) => regex.find(other.as_ref()).is_some(),
            (Object::Address(addr), Object::Identifier(identifier)) => {
                addr.local_part() == identifier.as_str()
            }
            (Object::Address(addr), Object::Fqdn(fqdn)) => addr.domain().to_string() == *fqdn,
            _ => false,
        }
    }

    /// check if the `other` string is contained in this object,
    /// return false automatically if the item cannot be contained in this object.
    #[must_use]
    pub fn contains_str(&self, other: &str) -> bool {
        match self {
            Object::Rg4(rg4) => ipnet::Ipv4Net::from_str(other)
                .map(|ip4| rg4.contains(&ip4))
                .unwrap_or(false),
            Object::Rg6(rg6) => ipnet::Ipv6Net::from_str(other)
                .map(|ip6| rg6.contains(&ip6))
                .unwrap_or(false),
            Object::Regex(regex) => regex.find(other).is_some(),
            Object::Address(addr) => {
                addr.local_part() == other || addr.domain().to_string() == other
            }
            _ => false,
        }
    }
}

impl PartialEq for Object {
    fn eq(&self, other: &Self) -> bool {
        match (self, other) {
            (Self::Ip4(l0), Self::Ip4(r0)) => l0 == r0,
            (Self::Ip6(l0), Self::Ip6(r0)) => l0 == r0,
            (Self::Rg4(l0), Self::Rg4(r0)) => l0 == r0,
            (Self::Rg6(l0), Self::Rg6(r0)) => l0 == r0,
            (Self::Address(l0), Self::Address(r0)) => l0 == r0,
            (Self::Fqdn(l0), Self::Fqdn(r0)) | (Self::Identifier(l0), Self::Identifier(r0)) => {
                l0 == r0
            }
            (Self::Regex(r0), Self::Regex(l0)) => r0.as_str() == l0.as_str(),
            (Self::Code(r0), Self::Code(l0)) => r0 == l0,

            // NOTE: do we want those two to be comparable ?
            // (Self::File(l0), Self::File(r0)) => l0 == r0,
            _ => false,
        }
    }
}

// Added to easily enable the user to print data of an object.
impl std::fmt::Display for Object {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Object::Ip4(ip) => write!(f, "{ip}"),
            Object::Ip6(ip) => write!(f, "{ip}"),
            Object::Rg4(range) => write!(f, "{range:?}"),
            Object::Rg6(range) => write!(f, "{range:?}"),
            Object::Address(addr) => write!(f, "{addr}"),
            Object::Fqdn(fqdn) => write!(f, "{fqdn}"),
            Object::Regex(regex) => write!(f, "{regex}"),
            Object::Identifier(ident) => write!(f, "{ident}"),
            Object::Code(reply) => write!(f, "{reply}"),
        }
    }
}

/// Wrap a new object in it's sync/async wrapper.
macro_rules! new_object {
    ($object:expr) => {
        Ok(rhai::Shared::new(
            $object.map_err::<Box<rhai::EvalAltResult>, _>(|e| e.to_string().into())?,
        ))
    };
}

type RhaiResultOf<T> = Result<T, Box<rhai::EvalAltResult>>;

#[rhai::plugin::export_module]
/// vSL objects declaration functions.
pub mod constructors {

    /// An object from the vSL rhai superset.
    pub type VSLObject = crate::objects::SharedObject;

    /// Build an ip4 address. (a.b.c.d)
    ///
    /// # rhai-autodocs:index:1
    #[rhai_fn(global, return_raw)]
    pub fn ip4(ip: &str) -> RhaiResultOf<VSLObject> {
        new_object!(Object::new_ip4(ip))
    }

    /// Build an ip6 address. (x:x:x:x:x:x:x:x)
    ///
    /// # rhai-autodocs:index:2
    #[rhai_fn(global, return_raw)]
    pub fn ip6(ip: &str) -> RhaiResultOf<VSLObject> {
        new_object!(Object::new_ip6(ip))
    }

    /// an ip v4 range. (a.b.c.d/range)
    ///
    /// # rhai-autodocs:index:3
    #[rhai_fn(global, return_raw)]
    pub fn rg4(range: &str) -> RhaiResultOf<VSLObject> {
        new_object!(Object::new_rg4(range))
    }

    /// an ip v6 range. (x:x:x:x:x:x:x:x/range)
    ///
    /// # rhai-autodocs:index:4
    #[rhai_fn(global, return_raw)]
    pub fn rg6(range: &str) -> RhaiResultOf<VSLObject> {
        new_object!(Object::new_rg6(range))
    }

    /// an email address (jones@foo.com)
    ///
    /// # rhai-autodocs:index:5
    #[rhai_fn(global, return_raw)]
    pub fn address(address: &str) -> RhaiResultOf<VSLObject> {
        new_object!(Object::new_address(address))
    }

    /// a valid fully qualified domain name (foo.com)
    ///
    /// # rhai-autodocs:index:6
    #[rhai_fn(global, return_raw)]
    pub fn fqdn(domain: &str) -> RhaiResultOf<VSLObject> {
        new_object!(Object::new_fqdn(domain))
    }

    /// a regex (^[a-z0-9.]+@foo.com$)
    ///
    /// # rhai-autodocs:index:7
    #[rhai_fn(global, return_raw)]
    pub fn regex(regex: &str) -> RhaiResultOf<VSLObject> {
        new_object!(Object::new_regex(regex))
    }

    /// the content of a file.
    ///
    /// # rhai-autodocs:index:8
    #[rhai_fn(global, return_raw)]
    pub fn file(path: &str, content_type: &str) -> RhaiResultOf<rhai::Array> {
        Object::new_file(path, content_type)
            .map_err::<Box<rhai::EvalAltResult>, _>(|e| e.to_string().into())
    }

    /// a user identifier.
    ///
    /// # rhai-autodocs:index:9
    #[rhai_fn(global)]
    pub fn identifier(identifier: &str) -> VSLObject {
        rhai::Shared::new(Object::new_identifier(identifier))
    }

    /// A SMTP code with the code and message as parameter.
    ///
    /// ```ignore
    /// let code = code(250, "Ok");
    /// let enhanced = code(451, "5.7.3", "STARTTLS is required to send mail");
    /// ```
    ///
    /// # rhai-autodocs:index:10
    #[rhai_fn(global, name = "code", return_raw)]
    pub fn code(code: rhai::INT, text: &str) -> RhaiResultOf<VSLObject> {
        Ok(rhai::Shared::new(Object::new_code(
            u16::try_from(code).map_err::<Box<rhai::EvalAltResult>, _>(|e| e.to_string().into())?,
            text,
        )))
    }

    /// A SMTP code with the code and message as parameter and an enhanced code.
    #[doc(hidden)]
    #[rhai_fn(global, name = "code", return_raw)]
    pub fn code_enhanced(code: rhai::INT, enhanced: &str, text: &str) -> RhaiResultOf<VSLObject> {
        Ok(rhai::Shared::new(Object::new_code_enhanced(
            u16::try_from(code).map_err::<Box<rhai::EvalAltResult>, _>(|e| e.to_string().into())?,
            enhanced,
            text,
        )))
    }
}

/// vSL objects utility methods.
#[rhai::plugin::export_module]
pub mod utils {
    use crate::objects::constructors::VSLObject;

    /// Get the local part of an email address.
    ///
    /// # Args
    ///
    /// * `address` - the address to extract the local part from.
    ///
    /// # Return
    ///
    /// * `String` - the local part.
    ///
    /// # Effective smtp stage
    ///
    /// All of them.
    ///
    /// # Examples
    ///
    /// ```text
    /// #{
    ///     mail: [
    ///         // You can also use the `get_local_part(ctx::mail_from())` syntax.
    ///         action "display mail from identity" || {
    ///             log("info", `received a message from ${ctx::mail_from().local_part}.`);
    ///         }
    ///     ],
    /// }
    /// ```
    ///
    /// # rhai-autodocs:index:1
    #[rhai_fn(global, get = "local_part", return_raw, pure)]
    pub fn local_part(addr: &mut VSLObject) -> RhaiResultOf<String> {
        match &**addr {
            Object::Address(addr) => Ok(addr.local_part().to_string()),
            other => Err(format!("cannot extract local part for {} object", other.as_ref()).into()),
        }
    }

    /// Get the domain of an email address.
    ///
    /// # Args
    ///
    /// * `address` - the address to extract the domain from.
    ///
    /// # Effective smtp stage
    ///
    /// All of them.
    ///
    /// # Examples
    ///
    /// ```text
    /// #{
    ///     mail: [
    ///         // You can also use the `get_domain(ctx::mail_from())` syntax.
    ///         action "display sender's domain" || {
    ///             log("info", `received a message from domain ${ctx::mail_from().domain}.`);
    ///         }
    ///     ],
    /// }
    /// ```
    ///
    /// # rhai-autodocs:index:2
    #[rhai_fn(global, get = "domain", return_raw, pure)]
    pub fn domain(addr: &mut VSLObject) -> RhaiResultOf<VSLObject> {
        match &**addr {
            Object::Address(addr) => Ok(rhai::Shared::new(Object::Fqdn(addr.domain().to_string()))),
            other => Err(format!("cannot extract domain for {} object", other.as_ref()).into()),
        }
    }

    // FIXME: prevent cloning by caching the result ?

    /// Get all local parts of the recipient list.
    ///
    /// # Args
    ///
    /// * `rcpt_list` - the recipient list.
    ///
    /// # Return
    ///
    /// * `array` - array of local parts.
    ///
    /// # Effective smtp stage
    ///
    /// `mail` and onwards.
    ///
    /// # Examples
    ///
    /// ```text
    /// #{
    ///     mail: [
    ///         action "display recipients usernames" || {
    ///             print("list of recipients user names:");
    ///
    ///             // You can also use the `get_local_parts(ctx::rcpt_list())` syntax.
    ///             for user in ctx::rcpt_list().local_parts {
    ///                 print(`- ${user}`);
    ///             }
    ///         }
    ///     ],
    /// }
    /// ```
    ///
    /// # rhai-autodocs:index:3
    #[rhai_fn(global, get = "local_parts", return_raw, pure)]
    pub fn local_parts(container: &mut rhai::Array) -> RhaiResultOf<rhai::Array> {
        container
            .iter()
            .map(|item| {
                if item.is::<SharedObject>() {
                    match &*item.clone_cast::<SharedObject>() {
                        Object::Address(addr) => {
                            Ok(rhai::Dynamic::from(addr.local_part().to_string()))
                        }
                        other => Err(format!(
                            "cannot extract local part for non email address ({})",
                            other.as_ref()
                        )
                        .into()),
                    }
                } else if item.is::<String>() {
                    let item = item.clone_cast::<String>();

                    // NOTE: Using this instead of [`Object::new_address`] because it would need an extra match.
                    <vsmtp_common::Address as std::str::FromStr>::from_str(item.as_str())
                        .map(|addr| rhai::Dynamic::from(addr.local_part().to_string()))
                        .map_err::<Box<rhai::EvalAltResult>, _>(|e| e.to_string().into())
                } else {
                    Err(format!(
                        "cannot extract local part from a {} object.",
                        item.type_name()
                    )
                    .into())
                }
            })
            .collect()
    }

    /// Get all domains of the recipient list.
    ///
    /// # Args
    ///
    /// * `rcpt_list` - the recipient list.
    ///
    /// # Effective smtp stage
    ///
    /// `mail` and onwards.
    ///
    /// # Examples
    ///
    /// ```text
    /// #{
    ///     mail: [
    ///         action "display recipients domains" || {
    ///             print("list of recipients domains:");
    ///
    ///             // You can also use the `get_domains(ctx::rcpt_list())` syntax.
    ///             for domain in ctx::rcpt_list().domains {
    ///                 print(`- ${domain}`);
    ///             }
    ///         }
    ///     ],
    /// }
    /// ```
    ///
    /// # rhai-autodocs:index:4
    #[rhai_fn(global, get = "domains", return_raw, pure)]
    pub fn domains(container: &mut rhai::Array) -> RhaiResultOf<rhai::Array> {
        container
            .iter()
            .map(|item| {
                if item.is::<SharedObject>() {
                    match &*item.clone_cast::<SharedObject>() {
                        Object::Address(addr) => Ok(rhai::Dynamic::from(addr.domain().to_string())),
                        other => Err(format!(
                            "cannot extract domain for non email address ({})",
                            other.as_ref()
                        )
                        .into()),
                    }
                } else if item.is::<String>() {
                    // TODO: handle rhai multi typed strings.
                    let item = item.clone_cast::<String>();

                    // NOTE: Using this instead of [`Object::new_address`] because it would need an extra match.
                    <vsmtp_common::Address as std::str::FromStr>::from_str(item.as_str())
                        .map(|addr| rhai::Dynamic::from(addr.domain().to_string()))
                        .map_err::<Box<rhai::EvalAltResult>, _>(|e| e.to_string().into())
                } else {
                    Err(format!("cannot extract domain from a {} object.", item.type_name()).into())
                }
            })
            .collect()
    }

    /// Convert a `SharedObject` to a `String`
    ///
    /// # rhai-autodocs:index:5
    #[rhai_fn(global, name = "to_string", pure)]
    pub fn object_to_string(this: &mut VSLObject) -> String {
        this.to_string()
    }

    /// Convert a `SharedObject` to a debug string
    ///
    /// # rhai-autodocs:index:6
    #[rhai_fn(global, name = "to_debug", pure)]
    pub fn object_to_debug(this: &mut VSLObject) -> String {
        format!("{:#?}", **this)
    }
}

/// vSL objects Eq method between each other and other types.
#[rhai::plugin::export_module]
pub mod comparisons {

    /// Operator `==` for `SharedObject`
    ///
    /// # rhai-autodocs:index:1
    #[rhai_fn(global, name = "==", pure)]
    pub fn object_is_self(this: &mut SharedObject, other: SharedObject) -> bool {
        **this == *other
    }

    /// Operator `!=` for `SharedObject`
    ///
    /// # rhai-autodocs:index:2
    #[rhai_fn(global, name = "!=", pure)]
    pub fn object_not_self(this: &mut SharedObject, other: SharedObject) -> bool {
        **this != *other
    }

    /// Operator `==` for `SharedObject` and `&str`
    ///
    /// # rhai-autodocs:index:3
    #[rhai_fn(global, name = "==", return_raw, pure)]
    pub fn object_is_string(this: &mut SharedObject, s: &str) -> RhaiResultOf<bool> {
        internal_string_is_object(s, this)
    }

    /// Operator `!=` for `SharedObject` and `&str`
    ///
    /// # rhai-autodocs:index:4
    #[rhai_fn(global, name = "!=", return_raw, pure)]
    pub fn object_not_string(this: &mut SharedObject, s: &str) -> RhaiResultOf<bool> {
        internal_string_is_object(s, this).map(|res| !res)
    }

    /// Operator `==` for `&str` and `SharedObject`
    ///
    /// # rhai-autodocs:index:5
    #[rhai_fn(global, name = "==", return_raw)]
    pub fn string_is_object(this: &str, other: SharedObject) -> RhaiResultOf<bool> {
        internal_string_is_object(this, &other)
    }

    /// Operator `!=` for `&str` and `SharedObject`
    ///
    /// # rhai-autodocs:index:6
    #[rhai_fn(global, name = "!=", return_raw)]
    pub fn string_not_object(this: &str, other: SharedObject) -> RhaiResultOf<bool> {
        internal_string_is_object(this, &other).map(|res| !res)
    }

    // NOTE: should this return an error if the string cannot be converted ?
    /// Operator `contains`
    ///
    /// # rhai-autodocs:index:7
    #[rhai_fn(global, name = "contains", pure)]
    pub fn string_in_object(this: &mut SharedObject, s: &str) -> bool {
        this.contains_str(s)
    }

    /// Operator `contains`
    ///
    /// # rhai-autodocs:index:8
    #[rhai_fn(global, name = "contains", pure)]
    pub fn object_in_object(this: &mut SharedObject, other: SharedObject) -> bool {
        this.contains(&other)
    }

    #[rhai_fn(global, name = "contains", pure)]
    ///
    /// # rhai-autodocs:index:9
    pub fn object_in_map(map: &mut rhai::Map, object: SharedObject) -> bool {
        // FIXME: impl Ord on Object to prevent cloning.
        map.contains_key(object.to_string().as_str())
    }
}

// the following methods are used to compare recursively deep objects
// using refs instead of shared rhai objects.
// FIXME: using generics here should be a good idea.
// TODO:  all comparison function should return an error in case of mismatching types ?

fn internal_string_is_object(this: &str, other: &Object) -> RhaiResultOf<bool> {
    match other {
        Object::Address(addr) => Ok(this == addr.full()),
        Object::Fqdn(fqdn) => Ok(this == fqdn.as_str()),
        Object::Regex(re) => Ok(re.is_match(this)),
        Object::Ip4(ip4) => Ok(this == ip4.to_string()),
        Object::Ip6(ip6) => Ok(this == ip6.to_string()),
        Object::Identifier(s) => Ok(this == s.as_str()),
        _ => Err(format!("a {other} object cannot be compared to a string").into()),
    }
}