// Copyright: Ankitects Pty Ltd and contributors
// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html

use crate::{
    collection::Collection,
    err::{AnkiError, DBErrorKind, Result},
    i18n::{tr_args, I18n, TR},
    notetype::{
        all_stock_notetypes, AlreadyGeneratedCardInfo, CardGenContext, NoteType, NoteTypeKind,
    },
    timestamp::{TimestampMillis, TimestampSecs},
};
use itertools::Itertools;
use slog::debug;
use std::{
    collections::{HashMap, HashSet},
    sync::Arc,
};

#[derive(Debug, Default, PartialEq)]
pub struct CheckDatabaseOutput {
    card_properties_invalid: usize,
    card_position_too_high: usize,
    cards_missing_note: usize,
    decks_missing: usize,
    revlog_properties_invalid: usize,
    templates_missing: usize,
    card_ords_duplicated: usize,
    field_count_mismatch: usize,
}

impl CheckDatabaseOutput {
    pub fn to_i18n_strings(&self, i18n: &I18n) -> Vec<String> {
        let mut probs = Vec::new();

        if self.card_position_too_high > 0 {
            probs.push(i18n.trn(
                TR::DatabaseCheckNewCardHighDue,
                tr_args!["count"=>self.card_position_too_high],
            ));
        }
        if self.card_properties_invalid > 0 {
            probs.push(i18n.trn(
                TR::DatabaseCheckCardProperties,
                tr_args!["count"=>self.card_properties_invalid],
            ));
        }
        if self.cards_missing_note > 0 {
            probs.push(i18n.trn(
                TR::DatabaseCheckCardMissingNote,
                tr_args!["count"=>self.cards_missing_note],
            ));
        }
        if self.decks_missing > 0 {
            probs.push(i18n.trn(
                TR::DatabaseCheckMissingDecks,
                tr_args!["count"=>self.decks_missing],
            ));
        }
        if self.field_count_mismatch > 0 {
            probs.push(i18n.trn(
                TR::DatabaseCheckFieldCount,
                tr_args!["count"=>self.field_count_mismatch],
            ));
        }
        if self.card_ords_duplicated > 0 {
            probs.push(i18n.trn(
                TR::DatabaseCheckDuplicateCardOrds,
                tr_args!["count"=>self.card_ords_duplicated],
            ));
        }
        if self.templates_missing > 0 {
            probs.push(i18n.trn(
                TR::DatabaseCheckMissingTemplates,
                tr_args!["count"=>self.templates_missing],
            ));
        }
        if self.revlog_properties_invalid > 0 {
            probs.push(i18n.trn(
                TR::DatabaseCheckRevlogProperties,
                tr_args!["count"=>self.revlog_properties_invalid],
            ));
        }

        probs
    }
}

impl Collection {
    /// Check the database, returning a list of problems that were fixed.
    pub(crate) fn check_database(&mut self) -> Result<CheckDatabaseOutput> {
        debug!(self.log, "quick check");
        if self.storage.quick_check_corrupt() {
            debug!(self.log, "quick check failed");
            return Err(AnkiError::DBError {
                info: self.i18n.tr(TR::DatabaseCheckCorrupt).into(),
                kind: DBErrorKind::Corrupt,
            });
        }

        debug!(self.log, "optimize");
        self.storage.optimize()?;

        self.transact(None, |col| col.check_database_inner())
    }

    fn check_database_inner(&mut self) -> Result<CheckDatabaseOutput> {
        let mut out = CheckDatabaseOutput::default();

        // cards first, as we need to be able to read them to process notes
        debug!(self.log, "check cards");
        self.check_card_properties(&mut out)?;
        self.check_orphaned_cards(&mut out)?;

        debug!(self.log, "check decks");
        self.check_missing_deck_ids(&mut out)?;
        self.check_filtered_cards(&mut out)?;

        debug!(self.log, "check notetypes");
        self.check_notetypes(&mut out)?;

        debug!(self.log, "check review log");
        self.check_revlog(&mut out)?;

        debug!(self.log, "missing decks");
        self.check_missing_deck_names(&mut out)?;

        self.update_next_new_position()?;

        debug!(self.log, "db check finished: {:#?}", out);

        Ok(out)
    }

    fn check_card_properties(&mut self, out: &mut CheckDatabaseOutput) -> Result<()> {
        let timing = self.timing_today()?;
        let (new_cnt, other_cnt) = self.storage.fix_card_properties(
            timing.days_elapsed,
            TimestampSecs::now(),
            self.usn()?,
        )?;
        out.card_position_too_high = new_cnt;
        out.card_properties_invalid += other_cnt;
        Ok(())
    }

    fn check_orphaned_cards(&mut self, out: &mut CheckDatabaseOutput) -> Result<()> {
        let cnt = self.storage.delete_orphaned_cards()?;
        if cnt > 0 {
            self.storage.set_schema_modified()?;
            out.cards_missing_note = cnt;
        }
        Ok(())
    }

    fn check_missing_deck_ids(&mut self, out: &mut CheckDatabaseOutput) -> Result<()> {
        let usn = self.usn()?;
        for did in self.storage.missing_decks()? {
            self.recover_missing_deck(did, usn)?;
            out.decks_missing += 1;
        }
        Ok(())
    }

    fn check_filtered_cards(&mut self, out: &mut CheckDatabaseOutput) -> Result<()> {
        let decks: HashMap<_, _> = self
            .storage
            .get_all_decks()?
            .into_iter()
            .map(|d| (d.id, d))
            .collect();

        let mut wrong = 0;
        for (cid, did) in self.storage.all_filtered_cards_by_deck()? {
            // we expect calling code to ensure all decks already exist
            if let Some(deck) = decks.get(&did) {
                if !deck.is_filtered() {
                    let mut card = self.storage.get_card(cid)?.unwrap();
                    card.odid.0 = 0;
                    card.odue = 0;
                    self.storage.update_card(&card)?;
                    wrong += 1;
                }
            }
        }

        if wrong > 0 {
            self.storage.set_schema_modified()?;
            out.card_properties_invalid += wrong;
        }

        Ok(())
    }

    fn check_notetypes(&mut self, out: &mut CheckDatabaseOutput) -> Result<()> {
        let nids_by_notetype = self.storage.all_note_ids_by_notetype()?;
        let norm = self.normalize_note_text();
        let usn = self.usn()?;
        let stamp = TimestampMillis::now();

        // will rebuild tag list below
        self.storage.clear_tags()?;

        for (ntid, group) in &nids_by_notetype.into_iter().group_by(|tup| tup.0) {
            debug!(self.log, "check notetype: {}", ntid);
            let mut group = group.peekable();
            let nt = match self.get_notetype(ntid)? {
                None => {
                    let first_note = self.storage.get_note(group.peek().unwrap().1)?.unwrap();
                    self.recover_notetype(stamp, first_note.fields.len())?
                }
                Some(nt) => nt,
            };

            let mut genctx = None;
            for (_, nid) in group {
                let mut note = self.storage.get_note(nid)?.unwrap();

                let cards = self.storage.existing_cards_for_note(nid)?;

                out.card_ords_duplicated += self.remove_duplicate_card_ordinals(&cards)?;
                out.templates_missing += self.remove_cards_without_template(&nt, &cards)?;

                // fix fields
                if note.fields.len() != nt.fields.len() {
                    note.fix_field_count(&nt);
                    note.tags.push("db-check".into());
                    out.field_count_mismatch += 1;
                }

                // write note, updating tags and generating missing cards
                let ctx = genctx.get_or_insert_with(|| CardGenContext::new(&nt, usn));
                self.update_note_inner_generating_cards(&ctx, &mut note, false, norm)?;
            }
        }

        // if the collection is empty and the user has deleted all note types, ensure at least
        // one note type exists
        if self.storage.get_all_notetype_names()?.is_empty() {
            let mut nt = all_stock_notetypes(&self.i18n).remove(0);
            self.add_notetype_inner(&mut nt, usn)?;
        }

        if out.card_ords_duplicated > 0 || out.field_count_mismatch > 0 || out.templates_missing > 0
        {
            self.storage.set_schema_modified()?;
        }

        Ok(())
    }

    fn remove_duplicate_card_ordinals(
        &mut self,
        cards: &[AlreadyGeneratedCardInfo],
    ) -> Result<usize> {
        let mut ords = HashSet::new();
        let mut removed = 0;
        for card in cards {
            if !ords.insert(card.ord) {
                self.storage.remove_card(card.id)?;
                removed += 1;
            }
        }

        Ok(removed)
    }

    fn remove_cards_without_template(
        &mut self,
        nt: &NoteType,
        cards: &[AlreadyGeneratedCardInfo],
    ) -> Result<usize> {
        if nt.config.kind() == NoteTypeKind::Cloze {
            return Ok(0);
        }
        let mut removed = 0;
        for card in cards {
            if card.ord as usize >= nt.templates.len() {
                self.storage.remove_card(card.id)?;
                removed += 1;
            }
        }

        Ok(removed)
    }

    fn recover_notetype(
        &mut self,
        stamp: TimestampMillis,
        field_count: usize,
    ) -> Result<Arc<NoteType>> {
        debug!(self.log, "create recovery notetype");
        let mut basic = all_stock_notetypes(&self.i18n).remove(0);
        let mut field = 3;
        while basic.fields.len() < field_count {
            basic.add_field(format!("{}", field));
            field += 1;
        }
        basic.name = format!("db-check-{}-{}", stamp, field_count);
        self.add_notetype(&mut basic)?;
        Ok(Arc::new(basic))
    }

    fn check_revlog(&self, out: &mut CheckDatabaseOutput) -> Result<()> {
        let cnt = self.storage.fix_revlog_properties()?;
        if cnt > 0 {
            self.storage.set_schema_modified()?;
            out.revlog_properties_invalid = cnt;
        }

        Ok(())
    }

    fn check_missing_deck_names(&mut self, out: &mut CheckDatabaseOutput) -> Result<()> {
        let names = self.storage.get_all_deck_names()?;
        out.decks_missing += self.add_missing_deck_names(&names)?;
        Ok(())
    }

    fn update_next_new_position(&self) -> Result<()> {
        let pos = self.storage.max_new_card_position().unwrap_or(0);
        self.set_next_card_position(pos)
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::{collection::open_test_collection, decks::DeckID, search::SortMode};

    #[test]
    fn cards() -> Result<()> {
        let mut col = open_test_collection();
        let nt = col.get_notetype_by_name("Basic")?.unwrap();
        let mut note = nt.new_note();
        col.add_note(&mut note, DeckID(1))?;

        // card properties
        col.storage
            .db
            .execute_batch("update cards set ivl=1.5,due=2000000,odue=1.5")?;

        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                card_properties_invalid: 2,
                card_position_too_high: 1,
                ..Default::default()
            }
        );
        // should be idempotent
        assert_eq!(col.check_database()?, Default::default());

        // missing deck
        col.storage.db.execute_batch("update cards set did=123")?;

        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                decks_missing: 1,
                ..Default::default()
            }
        );
        assert_eq!(
            col.storage.get_deck(DeckID(123))?.unwrap().name,
            "recovered123"
        );

        // missing note
        col.storage.remove_note(note.id)?;
        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                cards_missing_note: 1,
                ..Default::default()
            }
        );
        assert_eq!(
            col.storage.db_scalar::<u32>("select count(*) from cards")?,
            0
        );

        Ok(())
    }

    #[test]
    fn revlog() -> Result<()> {
        let mut col = open_test_collection();

        col.storage.db.execute_batch(
            "
        insert into revlog (id,cid,usn,ease,ivl,lastIvl,factor,time,type)
        values (0,0,0,0,1.5,1.5,0,0,0)",
        )?;

        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                revlog_properties_invalid: 1,
                ..Default::default()
            }
        );
        assert_eq!(
            col.storage
                .db_scalar::<bool>("select ivl = lastIvl = 1 from revlog")?,
            true
        );

        Ok(())
    }

    #[test]
    fn note_card_link() -> Result<()> {
        let mut col = open_test_collection();
        let nt = col.get_notetype_by_name("Basic")?.unwrap();
        let mut note = nt.new_note();
        col.add_note(&mut note, DeckID(1))?;

        // duplicate ordinals
        let cid = col.search_cards("", SortMode::NoOrder)?[0];
        let mut card = col.storage.get_card(cid)?.unwrap();
        card.id.0 += 1;
        col.storage.add_card(&mut card)?;

        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                card_ords_duplicated: 1,
                ..Default::default()
            }
        );
        assert_eq!(
            col.storage.db_scalar::<u32>("select count(*) from cards")?,
            1
        );

        // missing templates
        let cid = col.search_cards("", SortMode::NoOrder)?[0];
        let mut card = col.storage.get_card(cid)?.unwrap();
        card.id.0 += 1;
        card.ord = 10;
        col.storage.add_card(&mut card)?;

        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                templates_missing: 1,
                ..Default::default()
            }
        );
        assert_eq!(
            col.storage.db_scalar::<u32>("select count(*) from cards")?,
            1
        );

        Ok(())
    }

    #[test]
    fn note_fields() -> Result<()> {
        let mut col = open_test_collection();
        let nt = col.get_notetype_by_name("Basic")?.unwrap();
        let mut note = nt.new_note();
        col.add_note(&mut note, DeckID(1))?;

        // excess fields get joined into the last one
        col.storage
            .db
            .execute_batch("update notes set flds = 'a\x1fb\x1fc\x1fd'")?;
        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                field_count_mismatch: 1,
                ..Default::default()
            }
        );
        let note = col.storage.get_note(note.id)?.unwrap();
        assert_eq!(&note.fields, &["a", "b; c; d"]);

        // missing fields get filled with blanks
        col.storage
            .db
            .execute_batch("update notes set flds = 'a'")?;
        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                field_count_mismatch: 1,
                ..Default::default()
            }
        );
        let note = col.storage.get_note(note.id)?.unwrap();
        assert_eq!(&note.fields, &["a", ""]);

        Ok(())
    }

    #[test]
    fn deck_names() -> Result<()> {
        let mut col = open_test_collection();

        let deck = col.get_or_create_normal_deck("foo::bar::baz")?;
        // includes default
        assert_eq!(col.storage.get_all_deck_names()?.len(), 4);

        col.storage
            .db
            .prepare("delete from decks where id != ? and id != 1")?
            .execute(&[deck.id])?;
        assert_eq!(col.storage.get_all_deck_names()?.len(), 2);

        let out = col.check_database()?;
        assert_eq!(
            out,
            CheckDatabaseOutput {
                decks_missing: 1, // only counts the immediate parent that was missing
                ..Default::default()
            }
        );
        assert_eq!(
            &col.storage
                .get_all_deck_names()?
                .iter()
                .map(|(_, name)| name)
                .collect::<Vec<_>>(),
            &["Default", "foo", "foo::bar", "foo::bar::baz"]
        );

        Ok(())
    }
}