use std::cmp::Reverse;
use std::collections::HashSet;
use std::io::Write;

use big_s::S;
use bumpalo::Bump;
use either::{Either, Left, Right};
use heed::EnvOpenOptions;
use http_client::policy::IpPolicy;
use maplit::{btreemap, hashset};
use milli::progress::Progress;
use milli::update::new::indexer;
use milli::update::{IndexerConfig, MissingDocumentPolicy, Settings};
use milli::vector::RuntimeEmbedders;
use milli::{
    normalize_facet, AscDesc, Criterion, DocumentId, FilterableAttributesRule, Index, Member,
    MustStopProcessing, TermsMatchingStrategy,
};
use serde::{Deserialize, Deserializer};
use slice_group_by::GroupBy;

mod distinct;
mod facet_distribution;
mod filters;
mod phrase_search;
mod query_criteria;
mod sort;
mod typo_tolerance;

pub const TEST_QUERY: &str = "hello world america";

pub const EXTERNAL_DOCUMENTS_IDS: &[&str; 17] =
    &["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q"];

pub const CONTENT: &str = include_str!("../assets/test_set.ndjson");

pub fn setup_search_index_with_criteria(criteria: &[Criterion]) -> Index {
    let path = tempfile::tempdir().unwrap();
    let options = EnvOpenOptions::new();
    let mut options = options.read_txn_without_tls();
    options.map_size(10 * 1024 * 1024); // 10 MiB
    let index = Index::new(options, &path, milli::CreateOrOpen::create_without_shards()).unwrap();

    let mut wtxn = index.write_txn().unwrap();
    let config = IndexerConfig::default();

    let mut builder = Settings::new(&mut wtxn, &index, &config);

    builder.set_criteria(criteria.to_vec());
    builder.set_filterable_fields(vec![
        FilterableAttributesRule::Field(S("title")),
        FilterableAttributesRule::Field(S("tag")),
        FilterableAttributesRule::Field(S("asc_desc_rank")),
        FilterableAttributesRule::Field(S("_geo")),
        FilterableAttributesRule::Field(S("opt1")),
        FilterableAttributesRule::Field(S("opt1.opt2")),
        FilterableAttributesRule::Field(S("tag_in")),
    ]);
    builder.set_sortable_fields(hashset! {
        S("tag"),
        S("asc_desc_rank"),
    });
    builder.set_synonyms(btreemap! {
        S("hello") => vec![S("good morning")],
        S("world") => vec![S("earth")],
        S("america") => vec![S("the united states")],
    });
    builder.set_searchable_fields(vec![S("title"), S("description")]);
    builder
        .execute(
            &MustStopProcessing::default(),
            &Progress::default(),
            // NO DANGER: test
            &IpPolicy::danger_always_allow(),
            Default::default(),
        )
        .unwrap();
    wtxn.commit().unwrap();

    // index documents
    let config = IndexerConfig { max_memory: Some(10 * 1024 * 1024), ..Default::default() };
    let rtxn = index.read_txn().unwrap();
    let mut wtxn = index.write_txn().unwrap();

    let db_fields_ids_map = index.fields_ids_map(&rtxn).unwrap();
    let mut new_fields_ids_map = db_fields_ids_map.clone();

    let embedders = RuntimeEmbedders::default();
    let mut indexer = indexer::IndexOperations::new();

    let mut file = tempfile::tempfile().unwrap();
    file.write_all(CONTENT.as_bytes()).unwrap();
    file.sync_all().unwrap();
    let payload = unsafe { memmap2::Mmap::map(&file).unwrap() };

    // index documents
    indexer.replace_documents(&payload, MissingDocumentPolicy::default()).unwrap();

    let indexer_alloc = Bump::new();
    let (document_changes, operation_stats, primary_key) = indexer
        .into_changes(
            &indexer_alloc,
            &index,
            &rtxn,
            None,
            &mut new_fields_ids_map,
            &MustStopProcessing::default(),
            Progress::default(),
            None,
        )
        .unwrap();

    if let Some(error) = operation_stats.into_iter().find_map(|stat| stat.error) {
        panic!("{error}");
    }

    indexer::index(
        &mut wtxn,
        &index,
        &milli::ThreadPoolNoAbortBuilder::new().build().unwrap(),
        config.grenad_parameters(),
        &db_fields_ids_map,
        new_fields_ids_map,
        primary_key,
        &document_changes,
        embedders,
        &MustStopProcessing::default(),
        &Progress::default(),
        // NO DANGER: test
        &IpPolicy::danger_always_allow(),
        &Default::default(),
    )
    .unwrap();

    wtxn.commit().unwrap();
    drop(rtxn);

    index
}

pub fn internal_to_external_ids(index: &Index, internal_ids: &[DocumentId]) -> Vec<String> {
    let rtxn = index.read_txn().unwrap();
    let docid_map = index.external_documents_ids();
    let docid_map: std::collections::HashMap<_, _> = EXTERNAL_DOCUMENTS_IDS
        .iter()
        .map(|id| (docid_map.get(&rtxn, id).unwrap().unwrap(), id))
        .collect();
    internal_ids.iter().map(|id| docid_map.get(id).unwrap().to_string()).collect()
}

pub fn expected_order(
    criteria: &[Criterion],
    optional_words: TermsMatchingStrategy,
    sort_by: &[AscDesc],
) -> Vec<TestDocument> {
    let dataset =
        serde_json::Deserializer::from_str(CONTENT).into_iter().map(|r| r.unwrap()).collect();
    let mut groups: Vec<Vec<TestDocument>> = vec![dataset];

    for criterion in criteria {
        let mut new_groups = Vec::new();
        for group in groups.iter_mut() {
            match criterion {
                Criterion::Attribute => {
                    group.sort_by_key(|d| d.attribute_rank);
                    new_groups
                        .extend(group.linear_group_by_key(|d| d.attribute_rank).map(Vec::from));
                }
                Criterion::AttributeRank | Criterion::WordPosition => {
                    unreachable!("documents do not have attribute rank or position")
                }
                Criterion::Exactness => {
                    group.sort_by_key(|d| d.exact_rank);
                    new_groups.extend(group.linear_group_by_key(|d| d.exact_rank).map(Vec::from));
                }
                Criterion::Proximity => {
                    group.sort_by_key(|d| d.proximity_rank);
                    new_groups
                        .extend(group.linear_group_by_key(|d| d.proximity_rank).map(Vec::from));
                }
                Criterion::Sort if sort_by == [AscDesc::Asc(Member::Field(S("tag")))] => {
                    group.sort_by_key(|d| d.sort_by_rank);
                    new_groups.extend(group.linear_group_by_key(|d| d.sort_by_rank).map(Vec::from));
                }
                Criterion::Sort if sort_by == [AscDesc::Desc(Member::Field(S("tag")))] => {
                    group.sort_by_key(|d| Reverse(d.sort_by_rank));
                    new_groups.extend(group.linear_group_by_key(|d| d.sort_by_rank).map(Vec::from));
                }
                Criterion::Typo => {
                    group.sort_by_key(|d| d.typo_rank);
                    new_groups.extend(group.linear_group_by_key(|d| d.typo_rank).map(Vec::from));
                }
                Criterion::Words => {
                    group.sort_by_key(|d| d.word_rank);
                    new_groups.extend(group.linear_group_by_key(|d| d.word_rank).map(Vec::from));
                }
                Criterion::Asc(field_name) if field_name == "asc_desc_rank" => {
                    group.sort_by_key(|d| d.asc_desc_rank);
                    new_groups
                        .extend(group.linear_group_by_key(|d| d.asc_desc_rank).map(Vec::from));
                }
                Criterion::Desc(field_name) if field_name == "asc_desc_rank" => {
                    group.sort_by_key(|d| Reverse(d.asc_desc_rank));
                    new_groups
                        .extend(group.linear_group_by_key(|d| d.asc_desc_rank).map(Vec::from));
                }
                Criterion::Asc(_) | Criterion::Desc(_) | Criterion::Sort => {
                    new_groups.push(group.clone())
                }
            }
        }
        groups = std::mem::take(&mut new_groups);
    }

    match optional_words {
        TermsMatchingStrategy::Last => groups.into_iter().flatten().collect(),
        TermsMatchingStrategy::Frequency => groups.into_iter().flatten().collect(),
        TermsMatchingStrategy::All => {
            groups.into_iter().flatten().filter(|d| d.word_rank == 0).collect()
        }
    }
}

fn execute_filter(filter: &str, document: &TestDocument) -> Option<String> {
    let mut id = None;
    if let Some((field, filter)) = filter.split_once("!=") {
        if field == "tag" && document.tag != filter
            || (field == "asc_desc_rank"
                && Ok(&document.asc_desc_rank) != filter.parse::<u32>().as_ref())
        {
            id = Some(document.id.clone())
        }
    } else if let Some((field, filter)) = filter.split_once('=') {
        if field == "tag" && document.tag == filter
            || (field == "asc_desc_rank"
                && document.asc_desc_rank == filter.parse::<u32>().unwrap())
        {
            id = Some(document.id.clone())
        }
    } else if let Some((field, prefix)) = filter.split_once("STARTS WITH") {
        let field = match field.trim() {
            "tag" => &document.tag,
            "title" => &document.title,
            "description" => &document.description,
            _ => panic!("Unknown field: {field}"),
        };

        let field = normalize_facet(field);
        let prefix = normalize_facet(prefix.trim().trim_matches('\''));
        if field.starts_with(&prefix) {
            id = Some(document.id.clone());
        }
    } else if let Some(("asc_desc_rank", filter)) = filter.split_once('<') {
        if document.asc_desc_rank < filter.parse().unwrap() {
            id = Some(document.id.clone())
        }
    } else if let Some(("asc_desc_rank", filter)) = filter.split_once('>') {
        if document.asc_desc_rank > filter.parse().unwrap() {
            id = Some(document.id.clone())
        }
    } else if filter.starts_with("_geoRadius") {
        id = (document.geo_rank < 100000).then(|| document.id.clone());
    } else if filter.starts_with("NOT _geoRadius") {
        id = (document.geo_rank > 1000000).then(|| document.id.clone());
    } else if matches!(filter, "opt1 EXISTS" | "NOT opt1 NOT EXISTS") {
        id = document.opt1.is_some().then(|| document.id.clone());
    } else if matches!(filter, "NOT opt1 EXISTS" | "opt1 NOT EXISTS") {
        id = document.opt1.is_none().then(|| document.id.clone());
    } else if matches!(filter, "opt1.opt2 EXISTS") {
        if document.opt1opt2.is_some() {
            id = Some(document.id.clone());
        } else if let Some(opt1) = &document.opt1 {
            id = contains_key_rec(opt1, "opt2").then(|| document.id.clone());
        }
    } else if matches!(filter, "opt1 IS NULL" | "NOT opt1 IS NOT NULL") {
        id = document.opt1.as_ref().is_some_and(|v| v.is_null()).then(|| document.id.clone());
    } else if matches!(filter, "NOT opt1 IS NULL" | "opt1 IS NOT NULL") {
        id = document.opt1.as_ref().is_none_or(|v| !v.is_null()).then(|| document.id.clone());
    } else if matches!(filter, "opt1.opt2 IS NULL") {
        if document.opt1opt2.as_ref().is_some_and(|v| v.is_null()) {
            id = Some(document.id.clone());
        } else if let Some(opt1) = &document.opt1 {
            if !opt1.is_null() {
                id = contains_null_rec(opt1, "opt2").then(|| document.id.clone());
            }
        }
    } else if matches!(filter, "opt1 IS EMPTY" | "NOT opt1 IS NOT EMPTY") {
        id = document.opt1.as_ref().is_some_and(is_empty_value).then(|| document.id.clone());
    } else if matches!(filter, "NOT opt1 IS EMPTY" | "opt1 IS NOT EMPTY") {
        id = document.opt1.as_ref().is_none_or(|v| !is_empty_value(v)).then(|| document.id.clone());
    } else if matches!(filter, "opt1.opt2 IS EMPTY") {
        if document.opt1opt2.as_ref().is_some_and(is_empty_value) {
            id = Some(document.id.clone());
        }
    } else if matches!(
        filter,
        "tag_in IN[1, 2, 3, four, five]" | "NOT tag_in NOT IN[1, 2, 3, four, five]"
    ) {
        id = matches!(document.id.as_str(), "A" | "B" | "C" | "D" | "E")
            .then(|| document.id.clone());
    } else if matches!(filter, "tag_in NOT IN[1, 2, 3, four, five]") {
        id = (!matches!(document.id.as_str(), "A" | "B" | "C" | "D" | "E"))
            .then(|| document.id.clone());
    } else {
        panic!("Unknown filter: {filter}");
    }
    id
}

pub fn is_empty_value(v: &serde_json::Value) -> bool {
    match v {
        serde_json::Value::String(s) => s.is_empty(),
        serde_json::Value::Array(a) => a.is_empty(),
        serde_json::Value::Object(o) => o.is_empty(),
        _ => false,
    }
}

pub fn contains_key_rec(v: &serde_json::Value, key: &str) -> bool {
    match v {
        serde_json::Value::Array(v) => {
            for v in v.iter() {
                if contains_key_rec(v, key) {
                    return true;
                }
            }
            false
        }
        serde_json::Value::Object(v) => {
            for (k, v) in v.iter() {
                if k == key || contains_key_rec(v, key) {
                    return true;
                }
            }
            false
        }
        _ => false,
    }
}

pub fn contains_null_rec(v: &serde_json::Value, key: &str) -> bool {
    match v {
        serde_json::Value::Object(v) => {
            for (k, v) in v.iter() {
                if k == key && v.is_null() || contains_null_rec(v, key) {
                    return true;
                }
            }
            false
        }
        serde_json::Value::Array(v) => {
            for v in v.iter() {
                if contains_null_rec(v, key) {
                    return true;
                }
            }
            false
        }
        _ => false,
    }
}

pub fn expected_filtered_ids(filters: Vec<Either<Vec<&str>, &str>>) -> HashSet<String> {
    let dataset: Vec<TestDocument> =
        serde_json::Deserializer::from_str(CONTENT).into_iter().map(|r| r.unwrap()).collect();

    let mut filtered_ids: HashSet<_> = dataset.iter().map(|d| d.id.clone()).collect();
    for either in filters {
        let ids = match either {
            Left(array) => array
                .into_iter()
                .map(|f| {
                    let ids: HashSet<String> =
                        dataset.iter().filter_map(|d| execute_filter(f, d)).collect();
                    ids
                })
                .reduce(|a, b| a.union(&b).cloned().collect())
                .unwrap(),
            Right(filter) => {
                let ids: HashSet<String> =
                    dataset.iter().filter_map(|d| execute_filter(filter, d)).collect();
                ids
            }
        };

        filtered_ids = filtered_ids.intersection(&ids).cloned().collect();
    }

    filtered_ids
}

#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
pub struct TestDocument {
    pub id: String,
    pub word_rank: u32,
    pub typo_rank: u32,
    pub proximity_rank: u32,
    pub attribute_rank: u32,
    pub exact_rank: u32,
    pub asc_desc_rank: u32,
    pub sort_by_rank: u32,
    pub geo_rank: u32,
    pub title: String,
    pub description: String,
    pub tag: String,
    #[serde(default, deserialize_with = "some_option")]
    pub opt1: Option<serde_json::Value>,
    #[serde(default, deserialize_with = "some_option", rename = "opt1.opt2")]
    pub opt1opt2: Option<serde_json::Value>,
}

fn some_option<'de, D>(deserializer: D) -> Result<Option<serde_json::Value>, D::Error>
where
    D: Deserializer<'de>,
{
    let result = serde_json::Value::deserialize(deserializer)?;
    Ok(Some(result))
}
