use ldap3_proto::control::LdapControl;
use ldap3_proto::proto::{
    LdapOp, LdapPartialAttribute, LdapResult, LdapSearchRequest, LdapSearchResultEntry,
};
use ldap3_proto::{LdapMsg, LdapResultCode};

use crate::db::error::BoxedError;
use crate::db::{Database, DatabaseInterface, User};
use crate::ldap::filter::mail::{MailDomainError, MailFilter};
use crate::ldap::{Dn, LdapReturnError, LdapStream, LdapStreamError, MalformedDn};

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

#[derive(Debug)]
pub enum InvalidSearchDnKind {
    Malformed(MalformedDn),
    NoOu,
    MultipleOu,
}

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

    fn message(&self) -> String {
        match &self.kind {
            InvalidSearchDnKind::Malformed(_e) => format!("Malformed dn: {}", self.dn),
            InvalidSearchDnKind::NoOu => format!("Missing `ou` in search dn: {}", self.dn),
            InvalidSearchDnKind::MultipleOu => {
                format!("Multiple `ou` tables provided in search dn: {}", self.dn)
            }
        }
    }
}

#[derive(Clone, Debug)]
pub struct SearchDn(#[expect(unused)] Dn);

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

        let Some(ou) = dn.keys.get("ou") else {
            return Err(InvalidSearchDn {
                dn: input.to_string(),
                kind: InvalidSearchDnKind::NoOu,
            });
        };

        if ou.len() != 1 {
            return Err(InvalidSearchDn {
                dn: input.to_string(),
                kind: InvalidSearchDnKind::MultipleOu,
            });
        }

        Ok(Self(dn))
    }
}

#[derive(Debug)]
pub enum SearchError {
    Db(BoxedError),
    InvalidDn(InvalidSearchDn),
    MailDomain(MailDomainError),
}

impl SearchError {
    pub async fn error_message(
        &self,
        stream: &mut LdapStream,
        msgid: i32,
    ) -> Result<(), LdapStreamError> {
        let resp_msg = LdapMsg {
            msgid,
            op: LdapOp::SearchResultDone(LdapResult {
                code: self.code(),
                matcheddn: String::new(),
                message: self.message(),
                referral: vec![],
            }),
            ctrl: vec![],
        };

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

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

    fn message(&self) -> String {
        match self {
            Self::Db(e) => format!("Database error: {e}"),
            Self::InvalidDn(e) => e.message(),
            Self::MailDomain(e) => e.message(),
        }
    }
}

pub async fn search_success(
    stream: &mut LdapStream,
    msgid: i32,
    entries: Vec<(LdapSearchResultEntry, Vec<LdapControl>)>,
) -> Result<(), LdapStreamError> {
    let count = entries.len();

    for (entry, ctrl) in entries {
        tracing::debug!("Search result: {entry:?}");
        stream
            .send(LdapMsg {
                msgid,
                op: LdapOp::SearchResultEntry(entry),
                ctrl,
            })
            .await?;
    }

    stream
        .send(LdapMsg {
            msgid,
            op: LdapOp::SearchResultDone(LdapResult {
                code: LdapResultCode::Success,
                matcheddn: String::new(),
                message: format!("Found {count} result(s)"),
                referral: vec![],
            }),
            // TODO: implement LdapControl for pagination
            ctrl: vec![],
        })
        .await?;

    Ok(())
}

fn search_entry_from_user(user: &User, req_attrs: &[String]) -> LdapSearchResultEntry {
    let mut res: Vec<LdapPartialAttribute> = vec![];
    for attr in req_attrs {
        if let Some(attr_value) = match attr.as_str() {
            "uid" => Some(user.username.clone()),
            "cn" | "mail" => Some(user.mail.clone()),
            _ => {
                tracing::warn!("Ignoring unknown attr in search query: {attr}");
                None
            }
        } {
            res.push(LdapPartialAttribute {
                atype: attr.clone(),
                // TODO: there may be multiple values here in the future,
                // eg. mailaliases
                vals: vec![Vec::from(attr_value)],
            });
        }
    }

    LdapSearchResultEntry {
        dn: Dn::from_user(user).to_dn_string(),
        attributes: res,
    }
}

pub async fn search_by_mail_filter(
    stream: &mut LdapStream,
    db: &Database,
    sr: LdapSearchRequest,
    msgid: i32,
) -> Result<(), LdapStreamError> {
    // TODO: We should probably reuse the search DN somehow
    if let Err(e) = SearchDn::from_dn_str(&sr.base) {
        SearchError::InvalidDn(e)
            .error_message(stream, msgid)
            .await?;
        return Ok(());
    }

    let mail_filter = match MailFilter::from_search_filter(&sr.filter) {
        Ok(mail_filter) => mail_filter,
        Err(e) => {
            SearchError::MailDomain(e)
                .error_message(stream, msgid)
                .await?;
            return Ok(());
        }
    };

    let maybe_user = match db.get_user(&mail_filter.to_user_ref()).await {
        Ok(maybe_user) => maybe_user,
        Err(e) => {
            SearchError::Db(e).error_message(stream, msgid).await?;
            return Ok(());
        }
    };

    if let Some(user) = maybe_user {
        let entry_ctrl = (search_entry_from_user(&user, &sr.attrs), vec![]);
        search_success(stream, msgid, vec![entry_ctrl]).await?;
    } else {
        search_success(stream, msgid, vec![]).await?;
    }

    Ok(())
}