/*
 * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <hello@stalw.art>
 *
 * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
 */

use super::{ActiveScript, SeenIdHash, SieveScript};
use crate::{
    cache::{MessageCacheFetch, mailbox::MailboxCacheAccess},
    mailbox::{INBOX_ID, TRASH_ID, manage::MailboxFnc},
    message::{
        delivery::{AutogeneratedMessage, IngestRecipient},
        ingest::{EmailIngest, IngestEmail, IngestSource, IngestedEmail},
    },
};
use common::{Server, auth::AccessToken, scripts::plugins::PluginContext};
use mail_parser::MessageParser;
use sieve::{Envelope, Event, Input, Mailbox, Recipient, Sieve, SpamStatus};
use std::{borrow::Cow, sync::Arc};
use std::{future::Future, str::FromStr};
use store::{
    Deserialize, Serialize, ValueKey,
    ahash::AHashMap,
    dispatch::lookup::KeyValue,
    write::{
        AlignedBytes, Archive, ArchiveVersion, Archiver, BatchBuilder, BlobLink, BlobOp, ValueClass,
    },
};
use trc::{AddContext, SieveEvent};
use types::{
    blob_hash::BlobHash,
    collection::Collection,
    field::{PrincipalField, SieveField},
    id::Id,
    keyword::Keyword,
    special_use::SpecialUse,
};

struct SieveMessage<'x> {
    pub raw_message: Cow<'x, [u8]>,
    pub file_into: Vec<u32>,
    pub did_file_into: bool,
    pub flags: Vec<Keyword>,
}

pub trait SieveScriptIngest: Sync + Send {
    #[allow(clippy::too_many_arguments)]
    fn sieve_script_ingest(
        &self,
        access_token: &AccessToken,
        blob_hash: &BlobHash,
        raw_message: &[u8],
        envelope_from: &str,
        envelope_from_authenticated: bool,
        envelope_to: &IngestRecipient,
        session_id: u64,
        active_script: ActiveScript,
        autogenerated: &mut Vec<AutogeneratedMessage>,
    ) -> impl Future<Output = trc::Result<IngestedEmail>> + Send;

    fn sieve_script_get_active_id(
        &self,
        account_id: u32,
    ) -> impl Future<Output = trc::Result<Option<u32>>> + Send;

    fn sieve_script_get_active(
        &self,
        account_id: u32,
    ) -> impl Future<Output = trc::Result<Option<ActiveScript>>> + Send;

    fn sieve_script_get_by_name(
        &self,
        account_id: u32,
        name: &str,
    ) -> impl Future<Output = trc::Result<Option<Sieve>>> + Send;

    fn sieve_script_compile(
        &self,
        account_id: u32,
        document_id: u32,
    ) -> impl Future<Output = trc::Result<Option<CompiledScript>>> + Send;
}

impl SieveScriptIngest for Server {
    #[allow(clippy::blocks_in_conditions)]
    async fn sieve_script_ingest(
        &self,
        access_token: &AccessToken,
        blob_hash: &BlobHash,
        raw_message: &[u8],
        envelope_from: &str,
        envelope_from_authenticated: bool,
        envelope_to: &IngestRecipient,
        session_id: u64,
        active_script: ActiveScript,
        autogenerated: &mut Vec<AutogeneratedMessage>,
    ) -> trc::Result<IngestedEmail> {
        // Parse message
        let message = if let Some(message) = MessageParser::new().parse(raw_message) {
            message
        } else {
            return Err(
                trc::EventType::MessageIngest(trc::MessageIngestEvent::Error)
                    .ctx(trc::Key::Code, 550)
                    .ctx(trc::Key::Reason, "Failed to parse e-mail message."),
            );
        };

        // Obtain mailboxIds
        let account_id = access_token.account_id();
        let mut cache = self
            .get_cached_messages(account_id)
            .await
            .caused_by(trc::location!())?;

        // Create Sieve instance
        let mut instance = self.core.sieve.untrusted_runtime.filter_parsed(message);

        // Set account name and email
        let account_info = self.account(account_id).await.caused_by(trc::location!())?;
        let mail_from = account_info.name().to_string();
        instance.set_user_full_name(
            account_info
                .description()
                .unwrap_or_else(|| account_info.name()),
        );
        instance.set_user_address(&mail_from);

        // Set envelope
        instance.set_envelope(Envelope::From, envelope_from);
        instance.set_envelope(Envelope::To, envelope_to.address.as_str());
        if let Some(orcpt) = &envelope_to.orcpt {
            instance.set_envelope(Envelope::Orcpt, orcpt.as_str());
        }
        instance.set_spam_status(if envelope_to.is_spam {
            SpamStatus::Spam
        } else {
            SpamStatus::Ham
        });

        let mut input = Input::script(
            active_script.script_name.to_string(),
            active_script.script.clone(),
        );

        let mut do_discard = false;
        let mut do_deliver = false;
        let mut do_redirect = false;

        let mut reject_reason = None;
        let mut messages: Vec<SieveMessage> = vec![SieveMessage {
            raw_message: raw_message.into(),
            file_into: Vec::new(),
            flags: Vec::new(),
            did_file_into: false,
        }];
        let mut ingested_message = IngestedEmail {
            document_id: 0,
            thread_id: 0,
            change_id: u64::MAX,
            blob_id: Default::default(),
            size: raw_message.len(),
            imap_uids: Vec::new(),
        };
        let mut checked_ids: AHashMap<SeenIdHash, bool> = AHashMap::new();

        while let Some(event) = instance.run(input) {
            match event {
                Ok(event) => match event {
                    Event::IncludeScript { name, .. } => match &name {
                        sieve::Script::Personal(name_) => {
                            if let Ok(Some(script)) =
                                self.sieve_script_get_by_name(account_id, name_).await
                            {
                                input = Input::script(name, script);
                            } else {
                                input = false.into();
                            }
                        }
                        sieve::Script::Global(name_) => {
                            if let Some(script) =
                                self.get_untrusted_sieve_script(&name_.to_lowercase(), session_id)
                            {
                                input = Input::script(name, script.clone());
                            } else {
                                input = false.into();
                            }
                        }
                    },
                    Event::MailboxExists {
                        mailboxes,
                        special_use,
                    } => {
                        if !mailboxes.is_empty() {
                            let mut special_use_ids = Vec::with_capacity(special_use.len());
                            for role in special_use.iter().map(|v| SpecialUse::parse(v)) {
                                special_use_ids.push(match role {
                                    Some(SpecialUse::Inbox) => INBOX_ID,
                                    Some(SpecialUse::Trash) => TRASH_ID,
                                    Some(role) => cache
                                        .mailbox_by_role(&role)
                                        .map(|m| m.document_id)
                                        .unwrap_or(u32::MAX),
                                    None => u32::MAX,
                                });
                            }

                            let mut result = true;
                            for mailbox in mailboxes {
                                match mailbox {
                                    Mailbox::Name(name) => {
                                        if !matches!(
                                            cache.mailbox_by_path(&name),
                                            Some(item) if special_use_ids.is_empty() ||
                                            special_use_ids.contains(&item.document_id)
                                        ) {
                                            result = false;
                                            break;
                                        }
                                    }
                                    Mailbox::Id(id) => {
                                        if !matches!(Id::from_str(&id), Ok(id) if
                                                        cache.has_mailbox_id(&id.document_id()) &&
                                                        (special_use_ids.is_empty() ||
                                                        special_use_ids.contains(&id.document_id())))
                                        {
                                            result = false;
                                            break;
                                        }
                                    }
                                }
                            }
                            input = result.into();
                        } else if !special_use.is_empty() {
                            let mut result = true;

                            for role in special_use.iter().map(|v| SpecialUse::parse(v)) {
                                match role {
                                    Some(SpecialUse::Inbox | SpecialUse::Trash) => {}
                                    Some(other) if cache.mailbox_by_role(&other).is_some() => {}
                                    _ => {
                                        result = false;
                                        break;
                                    }
                                }
                            }
                            input = result.into();
                        } else {
                            input = false.into();
                        }
                    }
                    Event::DuplicateId { id, expiry, last } => {
                        let id_hash = SeenIdHash::new(
                            account_id,
                            active_script.version.hash().unwrap_or_default(),
                            &id,
                        );
                        if let Some(result) = checked_ids.get(&id_hash) {
                            input = (*result).into();
                        } else {
                            let exists = self
                                .in_memory_store()
                                .key_exists(id_hash.key())
                                .await
                                .caused_by(trc::location!())?;

                            if !exists || last {
                                self.in_memory_store()
                                    .key_set(KeyValue::new(id_hash.key(), vec![]).expires(expiry))
                                    .await
                                    .caused_by(trc::location!())?;
                            }

                            checked_ids.insert(id_hash, exists);
                            input = exists.into();
                        }
                    }
                    Event::Discard => {
                        do_discard = true;
                        input = true.into();
                    }
                    Event::Reject { reason, .. } => {
                        reject_reason = reason.into();
                        do_discard = true;
                        input = true.into();
                    }
                    Event::Keep { flags, message_id } => {
                        if let Some(message) = messages.get_mut(message_id) {
                            message.flags = flags.into_iter().map(Keyword::from).collect();
                            if !message.file_into.contains(&INBOX_ID) {
                                message.file_into.push(INBOX_ID);
                            }
                            do_deliver = true;
                        } else {
                            trc::event!(
                                Sieve(SieveEvent::UnexpectedError),
                                Details = "Unknown message id.",
                                MessageId = message_id,
                                SpanId = session_id
                            );
                        }
                        input = true.into();
                    }
                    Event::FileInto {
                        folder,
                        flags,
                        mailbox_id,
                        special_use,
                        create,
                        message_id,
                    } => {
                        let mut target_id = u32::MAX;

                        // Find mailbox by Id
                        if let Some(mailbox_id) = mailbox_id.and_then(|m| Id::from_str(&m).ok()) {
                            let mailbox_id = mailbox_id.document_id();
                            if cache.has_mailbox_id(&mailbox_id) {
                                target_id = mailbox_id;
                            }
                        }

                        // Find mailbox by role
                        if target_id == u32::MAX
                            && let Some(special_use) =
                                special_use.as_deref().and_then(SpecialUse::parse)
                        {
                            match special_use {
                                SpecialUse::Inbox => {
                                    target_id = INBOX_ID;
                                }
                                SpecialUse::Trash => {
                                    target_id = TRASH_ID;
                                }
                                role => {
                                    if let Some(item) = cache.mailbox_by_role(&role) {
                                        target_id = item.document_id;
                                    }
                                }
                            }
                        }

                        // Find mailbox by name
                        if target_id == u32::MAX {
                            if !create {
                                if let Some(m) = cache.mailbox_by_path(&folder) {
                                    target_id = m.document_id;
                                }
                            } else if let Some(document_id) = self
                                .mailbox_create_path(account_id, &folder)
                                .await
                                .caused_by(trc::location!())?
                            {
                                cache = self
                                    .get_cached_messages(account_id)
                                    .await
                                    .caused_by(trc::location!())?;
                                target_id = document_id;
                            }
                        }

                        // Default to Inbox
                        if target_id == u32::MAX {
                            target_id = INBOX_ID;
                        }

                        if let Some(message) = messages.get_mut(message_id) {
                            message.flags = flags.into_iter().map(Keyword::from).collect();
                            if !message.file_into.contains(&target_id) {
                                message.file_into.push(target_id);
                            }
                            message.did_file_into = true;
                            do_deliver = true;
                        } else {
                            trc::event!(
                                Sieve(SieveEvent::UnexpectedError),
                                Details = "Unknown message id.",
                                MessageId = message_id,
                                SpanId = session_id
                            );
                        }
                        input = true.into();
                    }
                    Event::SendMessage {
                        recipient,
                        message_id,
                        ..
                    } => {
                        input = true.into();
                        if let Some(message) = messages.get(message_id) {
                            let recipients: Vec<String> = match recipient {
                                Recipient::Address(rcpt) => vec![rcpt],
                                Recipient::Group(rcpts) => rcpts,
                                Recipient::List(_) => {
                                    // Not yet implemented
                                    continue;
                                }
                            };

                            if message.raw_message.len() <= self.core.email.mail_max_size {
                                trc::event!(
                                    Sieve(SieveEvent::SendMessage),
                                    From = mail_from.clone(),
                                    To = recipients
                                        .iter()
                                        .map(|r| trc::Value::String(r.as_str().into()))
                                        .collect::<Vec<_>>(),
                                    Size = message.raw_message.len(),
                                    SpanId = session_id
                                );

                                autogenerated.push(AutogeneratedMessage {
                                    sender_address: mail_from.clone(),
                                    recipients,
                                    message: message.raw_message.to_vec(),
                                });
                                do_redirect = true;
                            } else {
                                trc::event!(
                                    Sieve(SieveEvent::MessageTooLarge),
                                    From = mail_from.clone(),
                                    To = recipients
                                        .iter()
                                        .map(|r| trc::Value::String(r.as_str().into()))
                                        .collect::<Vec<_>>(),
                                    Size = message.raw_message.len(),
                                    Limit = self.core.email.mail_max_size,
                                    SpanId = session_id,
                                );
                            }
                        } else {
                            trc::event!(
                                Sieve(SieveEvent::UnexpectedError),
                                Details = "Unknown message id.",
                                MessageId = message_id,
                                SpanId = session_id
                            );

                            continue;
                        }
                    }
                    Event::ListContains { .. }
                    | Event::Notify { .. }
                    | Event::SetEnvelope { .. } => {
                        // Not allowed
                        input = false.into();
                    }
                    Event::Function { id, arguments } => {
                        input = self
                            .core
                            .run_plugin(
                                id,
                                PluginContext {
                                    session_id,
                                    server: self,
                                    message: instance.message(),
                                    modifications: &mut Vec::new(),
                                    access_token: access_token.into(),
                                    arguments,
                                },
                            )
                            .await;
                    }
                    Event::CreatedMessage { message, .. } => {
                        messages.push(SieveMessage {
                            raw_message: message.into(),
                            file_into: Vec::new(),
                            flags: Vec::new(),
                            did_file_into: false,
                        });
                        input = true.into();
                    }
                },

                #[cfg(feature = "test_mode")]
                Err(sieve::runtime::RuntimeError::ScriptErrorMessage(err)) => {
                    panic!("Sieve test failed: {}", err);
                }

                Err(err) => {
                    trc::event!(
                        Sieve(SieveEvent::RuntimeError),
                        Reason = err.to_string(),
                        SpanId = session_id
                    );

                    input = true.into();
                }
            }
        }

        // Fail-safe, no discard and no keep seen, assume that something went wrong and file anyway.
        if !do_deliver && !do_discard && !do_redirect {
            messages[0].file_into.push(INBOX_ID);
        }

        // Deliver messages
        let mut last_temp_error = None;
        let mut has_delivered = false;
        for (message_id, sieve_message) in messages.into_iter().enumerate() {
            if !sieve_message.file_into.is_empty() {
                // Parse message if needed
                let (blob_hash, message) = if message_id == 0 && !instance.has_message_changed() {
                    (blob_hash.into(), instance.take_message())
                } else if let Some(message) =
                    MessageParser::new().parse(sieve_message.raw_message.as_ref())
                {
                    (None, message)
                } else {
                    trc::event!(
                        Sieve(SieveEvent::UnexpectedError),
                        Details = "Failed to parse Sieve generated message.",
                        SpanId = session_id
                    );

                    continue;
                };

                // Deliver message
                match self
                    .email_ingest(IngestEmail {
                        raw_message: &sieve_message.raw_message,
                        blob_hash,
                        message: message.into(),
                        access_token,
                        mailbox_ids: sieve_message.file_into,
                        keywords: sieve_message.flags,
                        received_at: None,
                        source: IngestSource::Smtp {
                            deliver_to: envelope_to.address.as_str(),
                            is_sender_authenticated: envelope_from_authenticated,
                            is_spam: envelope_to.is_spam,
                        },
                        session_id,
                    })
                    .await
                {
                    Ok(ingested_message_) => {
                        has_delivered = true;
                        ingested_message = ingested_message_;
                    }
                    Err(err) => {
                        last_temp_error = err.into();
                    }
                }
            }
        }

        if let Some(reject_reason) = reject_reason {
            Err(
                trc::EventType::MessageIngest(trc::MessageIngestEvent::Error)
                    .ctx(trc::Key::Code, 571)
                    .ctx(trc::Key::Reason, reject_reason),
            )
        } else if has_delivered || last_temp_error.is_none() {
            Ok(ingested_message)
        } else {
            // There were problems during delivery
            #[allow(clippy::unnecessary_unwrap)]
            Err(last_temp_error.unwrap())
        }
    }

    async fn sieve_script_get_active_id(&self, account_id: u32) -> trc::Result<Option<u32>> {
        self.store()
            .get_value::<u32>(ValueKey {
                account_id,
                collection: Collection::Principal.into(),
                document_id: 0,
                class: ValueClass::Property(PrincipalField::ActiveScriptId.into()),
            })
            .await
            .caused_by(trc::location!())
    }

    async fn sieve_script_get_active(&self, account_id: u32) -> trc::Result<Option<ActiveScript>> {
        // Find the currently active script
        if let Some(document_id) = self
            .store()
            .get_value::<u32>(ValueKey {
                account_id,
                collection: Collection::Principal.into(),
                document_id: 0,
                class: ValueClass::Property(PrincipalField::ActiveScriptId.into()),
            })
            .await
            .caused_by(trc::location!())?
        {
            if let Some(script) = self.sieve_script_compile(account_id, document_id).await? {
                Ok(Some(ActiveScript {
                    document_id,
                    script: Arc::new(script.script),
                    script_name: script.name,
                    version: script.version,
                }))
            } else {
                Ok(None)
            }
        } else {
            Ok(None)
        }
    }

    async fn sieve_script_get_by_name(
        &self,
        account_id: u32,
        name: &str,
    ) -> trc::Result<Option<Sieve>> {
        // Find the script by name
        if let Some(document_id) = self
            .document_ids_matching(
                account_id,
                Collection::SieveScript,
                SieveField::Name,
                name.to_lowercase().as_bytes(),
            )
            .await
            .caused_by(trc::location!())?
            .min()
        {
            self.sieve_script_compile(account_id, document_id)
                .await
                .map(|script| script.map(|s| s.script))
        } else {
            Ok(None)
        }
    }

    #[allow(clippy::blocks_in_conditions)]
    async fn sieve_script_compile(
        &self,
        account_id: u32,
        document_id: u32,
    ) -> trc::Result<Option<CompiledScript>> {
        // Obtain script object
        let Some(script_object) = self
            .store()
            .get_value::<Archive<AlignedBytes>>(ValueKey::archive(
                account_id,
                Collection::SieveScript,
                document_id,
            ))
            .await?
        else {
            return Ok(None);
        };

        // Obtain the sieve script length
        let version = script_object.version;
        let unarchived_script = script_object
            .unarchive::<SieveScript>()
            .caused_by(trc::location!())?;
        let script_offset = u32::from(unarchived_script.size) as usize;

        // Obtain the sieve script blob
        let script_bytes = self
            .core
            .storage
            .blob
            .get_blob(unarchived_script.blob_hash.0.as_ref(), 0..usize::MAX)
            .await
            .caused_by(trc::location!())?
            .ok_or_else(|| {
                trc::StoreEvent::NotFound
                    .into_err()
                    .caused_by(trc::location!())
                    .document_id(document_id)
            })?;

        // Obtain the precompiled script
        if let Some(script) = script_bytes.get(script_offset..).and_then(|bytes| {
            <Archive<AlignedBytes> as Deserialize>::deserialize(bytes)
                .ok()?
                .deserialize::<Sieve>()
                .ok()
        }) {
            Ok(Some(CompiledScript {
                script,
                name: unarchived_script.name.as_str().into(),
                version,
            }))
        } else {
            // Deserialization failed, probably because the script compiler version changed
            match self.core.sieve.untrusted_compiler.compile(
                script_bytes.get(0..script_offset).ok_or_else(|| {
                    trc::StoreEvent::NotFound
                        .into_err()
                        .caused_by(trc::location!())
                        .document_id(document_id)
                })?,
            ) {
                Ok(sieve) => {
                    // Store updated compiled sieve script
                    let sieve = Archiver::new(sieve).untrusted();
                    let compiled_bytes = sieve.serialize().caused_by(trc::location!())?;
                    let mut updated_sieve_bytes =
                        Vec::with_capacity(script_offset + compiled_bytes.len());
                    updated_sieve_bytes.extend_from_slice(&script_bytes[0..script_offset]);
                    updated_sieve_bytes.extend_from_slice(&compiled_bytes);

                    // Store updated blob
                    let (new_blob_hash, new_blob_hold) = self
                        .put_temporary_blob(account_id, &updated_sieve_bytes, 60)
                        .await?;
                    let mut new_script_object =
                        rkyv::deserialize(unarchived_script).caused_by(trc::location!())?;
                    let blob_hash =
                        std::mem::replace(&mut new_script_object.blob_hash, new_blob_hash.clone());
                    let new_archive = Archiver::new(new_script_object);

                    // Update script object
                    let mut batch = BatchBuilder::new();
                    batch
                        .with_account_id(account_id)
                        .with_collection(Collection::SieveScript)
                        .with_document(document_id)
                        .assert_value(SieveField::Archive, &script_object)
                        .set(
                            SieveField::Archive,
                            new_archive.serialize().caused_by(trc::location!())?,
                        )
                        .clear(BlobOp::Link {
                            hash: blob_hash,
                            to: BlobLink::Document,
                        })
                        .set(
                            BlobOp::Link {
                                hash: new_blob_hash,
                                to: BlobLink::Document,
                            },
                            Vec::new(),
                        )
                        .clear(new_blob_hold);
                    self.store()
                        .write(batch.build_all())
                        .await
                        .caused_by(trc::location!())?;

                    Ok(Some(CompiledScript {
                        script: sieve.into_inner(),
                        name: new_archive.into_inner().name,
                        version,
                    }))
                }
                Err(error) => Err(trc::StoreEvent::UnexpectedError
                    .caused_by(trc::location!())
                    .reason(error)
                    .details("Failed to compile Sieve script")),
            }
        }
    }
}

pub struct CompiledScript {
    pub script: Sieve,
    pub name: String,
    pub version: ArchiveVersion,
}
