use ldap3_proto::proto::{LdapBindCred, LdapBindRequest, LdapBindResponse, LdapOp, LdapResult};
use ldap3_proto::{LdapMsg, LdapResultCode};

use crate::db::error::BoxedError;
use crate::db::{Database, DatabaseInterface, UserRef};
use crate::ldap::{Dn, LdapReturnError, LdapStream, LdapStreamError, MalformedDn};

#[derive(Debug)]
pub struct InvalidBindDn {
    dn: String,
    kind: InvalidBindDnKind,
}

#[derive(Debug)]
pub enum InvalidBindDnKind {
    Malformed(MalformedDn),
    NoUid,
    MultipleUid,
    NoDc,
}

impl LdapReturnError for InvalidBindDn {
    fn code(&self) -> LdapResultCode {
        LdapResultCode::InvalidDNSyntax
    }

    fn message(&self) -> String {
        match &self.kind {
            InvalidBindDnKind::Malformed(_e) => format!("Malformed dn: {}", self.dn),
            InvalidBindDnKind::NoUid => format!("Missing `uid` in bind dn: {}", self.dn),
            InvalidBindDnKind::MultipleUid => {
                format!("Multiple `uid` accounts provided in bind dn: {}", self.dn)
            }
            InvalidBindDnKind::NoDc => format!("Missing `dc` in bind dn: {}", self.dn),
        }
    }
}

#[derive(Clone, Debug)]
pub struct BindDn(Dn);

impl BindDn {
    pub fn from_dn_str(input: &str) -> Result<Self, InvalidBindDn> {
        let dn = Dn::from_dn_str(input).map_err(|e| InvalidBindDn {
            dn: input.to_string(),
            kind: InvalidBindDnKind::Malformed(e),
        })?;

        let Some(uid) = dn.keys.get("uid") else {
            return Err(InvalidBindDn {
                dn: input.to_string(),
                kind: InvalidBindDnKind::NoUid,
            });
        };

        if uid.len() != 1 {
            return Err(InvalidBindDn {
                dn: input.to_string(),
                kind: InvalidBindDnKind::MultipleUid,
            });
        }

        if dn.get_hostname().is_none() {
            return Err(InvalidBindDn {
                dn: input.to_string(),
                kind: InvalidBindDnKind::NoDc,
            });
        }

        Ok(Self(dn))
    }

    pub fn to_dn_string(&self) -> String {
        self.0.to_dn_string()
    }

    pub fn to_user_ref(&self) -> UserRef {
        let username = self.0.keys.get("uid").unwrap()[0].clone();
        let domain = self.0.keys.get("dc").unwrap().join(".");

        UserRef { username, domain }
    }
}

#[derive(Debug)]
pub enum BindError {
    Db(BoxedError),
    InvalidCredentials,
    InvalidDn(InvalidBindDn),
    UnsupportedSASL,
}

impl BindError {
    pub async fn error_message(
        &self,
        stream: &mut LdapStream,
        msgid: i32,
    ) -> Result<(), LdapStreamError> {
        tracing::debug!(error=?self, "Bind failed");
        let resp_msg = LdapMsg {
            msgid,
            op: LdapOp::BindResponse(LdapBindResponse {
                res: LdapResult {
                    code: self.code(),
                    matcheddn: String::new(),
                    message: self.message(),
                    referral: vec![],
                },
                saslcreds: None,
            }),
            ctrl: vec![],
        };

        stream.send(resp_msg).await?;
        Ok(())
    }
}

impl LdapReturnError for BindError {
    fn code(&self) -> LdapResultCode {
        match self {
            Self::Db(_e) => LdapResultCode::Unavailable,
            Self::InvalidCredentials => LdapResultCode::InvalidCredentials,
            Self::InvalidDn(e) => e.code(),
            Self::UnsupportedSASL => LdapResultCode::OperationsError,
        }
    }

    fn message(&self) -> String {
        match self {
            Self::Db(e) => format!("Database error: {e}"),
            Self::InvalidCredentials => "Wrong username or password".to_string(),
            Self::InvalidDn(e) => e.message(),
            Self::UnsupportedSASL => "SASL login is not supported".to_string(),
        }
    }
}

pub async fn bind_success(stream: &mut LdapStream, msgid: i32) -> Result<(), LdapStreamError> {
    let resp_msg = LdapMsg {
        msgid,
        op: LdapOp::BindResponse(LdapBindResponse {
            res: LdapResult {
                code: LdapResultCode::Success,
                matcheddn: String::new(),
                message: String::new(),
                referral: vec![],
            },
            saslcreds: None,
        }),
        ctrl: vec![],
    };

    stream.send(resp_msg).await?;
    Ok(())
}

/// Tries to bind the user.
///
/// On success, returns `Ok(Some(bound_dn))`. `Ok(None)` means credentials failed,
/// either because the account does not exist, or the password is wrong.
pub async fn op_bind<D: DatabaseInterface>(
    stream: &mut LdapStream,
    db: &Database<D>,
    req: LdapBindRequest,
    msgid: i32,
) -> Result<Option<BindDn>, LdapStreamError> {
    // Anonymous bind
    if req.dn.is_empty() {
        bind_success(stream, msgid).await?;
        return Ok(None);
    }

    let dn = match BindDn::from_dn_str(&req.dn) {
        Ok(dn) => dn,
        Err(e) => {
            BindError::InvalidDn(e).error_message(stream, msgid).await?;
            return Ok(None);
        }
    };

    let LdapBindCred::Simple(password) = req.cred else {
        BindError::UnsupportedSASL
            .error_message(stream, msgid)
            .await?;
        return Ok(None);
    };

    let success = match db.check_password(&dn.to_user_ref(), &password).await {
        Ok(success) => success,
        Err(e) => {
            // tracing::error!(error = &*e as &dyn std::error::Error, "Database failure");
            tracing::error!(error = e, "Database failure");
            BindError::Db(e).error_message(stream, msgid).await?;
            return Ok(None);
        }
    };

    if success {
        bind_success(stream, msgid).await?;
        Ok(Some(dn))
    } else {
        BindError::InvalidCredentials
            .error_message(stream, msgid)
            .await?;
        Ok(None)
    }
}