use std::collections::{BTreeMap, BTreeSet};
use std::marker::PhantomData;
use std::num::NonZeroUsize;

use milli::update::Setting;
use serde::{Deserialize, Serialize, Serializer};

fn serialize_with_wildcard<S>(
    field: &Setting<Vec<String>>,
    s: S,
) -> std::result::Result<S::Ok, S::Error>
where
    S: Serializer,
{
    let wildcard = vec!["*".to_string()];
    match field {
        Setting::Set(value) => Some(value),
        Setting::Reset => Some(&wildcard),
        Setting::NotSet => None,
    }
    .serialize(s)
}

#[derive(Clone, Default, Debug, Serialize, PartialEq, Eq)]
pub struct Checked;

#[derive(Clone, Default, Debug, Serialize, Deserialize, PartialEq, Eq)]
pub struct Unchecked;

#[cfg_attr(test, derive(proptest_derive::Arbitrary))]
#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq)]
#[serde(deny_unknown_fields)]
#[serde(rename_all = "camelCase")]
pub struct MinWordSizeTyposSetting {
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    pub one_typo: Setting<u8>,
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    pub two_typos: Setting<u8>,
}

#[cfg_attr(test, derive(proptest_derive::Arbitrary))]
#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq)]
#[serde(deny_unknown_fields)]
#[serde(rename_all = "camelCase")]
pub struct TypoSettings {
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    pub enabled: Setting<bool>,
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    pub min_word_size_for_typos: Setting<MinWordSizeTyposSetting>,
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    pub disable_on_words: Setting<BTreeSet<String>>,
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    pub disable_on_attributes: Setting<BTreeSet<String>>,
}

#[cfg_attr(test, derive(proptest_derive::Arbitrary))]
#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq)]
#[serde(deny_unknown_fields)]
#[serde(rename_all = "camelCase")]
pub struct FacetingSettings {
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    pub max_values_per_facet: Setting<usize>,
}

#[cfg_attr(test, derive(proptest_derive::Arbitrary))]
#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq)]
#[serde(deny_unknown_fields)]
#[serde(rename_all = "camelCase")]
pub struct PaginationSettings {
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    pub max_total_hits: Setting<usize>,
}

/// Holds all the settings for an index. `T` can either be `Checked` if they represents settings
/// whose validity is guaranteed, or `Unchecked` if they need to be validated. In the later case, a
/// call to `check` will return a `Settings<Checked>` from a `Settings<Unchecked>`.
#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq)]
#[serde(deny_unknown_fields)]
#[serde(rename_all = "camelCase")]
#[serde(bound(serialize = "T: Serialize", deserialize = "T: Deserialize<'static>"))]
#[cfg_attr(test, derive(proptest_derive::Arbitrary))]
pub struct Settings<T> {
    #[serde(
        default,
        serialize_with = "serialize_with_wildcard",
        skip_serializing_if = "Setting::is_not_set"
    )]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub displayed_attributes: Setting<Vec<String>>,

    #[serde(
        default,
        serialize_with = "serialize_with_wildcard",
        skip_serializing_if = "Setting::is_not_set"
    )]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub searchable_attributes: Setting<Vec<String>>,

    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub filterable_attributes: Setting<BTreeSet<String>>,
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub sortable_attributes: Setting<BTreeSet<String>>,
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub ranking_rules: Setting<Vec<String>>,
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub stop_words: Setting<BTreeSet<String>>,
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub synonyms: Setting<BTreeMap<String, Vec<String>>>,
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub distinct_attribute: Setting<String>,
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub typo_tolerance: Setting<TypoSettings>,
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub faceting: Setting<FacetingSettings>,
    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
    #[cfg_attr(test, proptest(strategy = "test::setting_strategy()"))]
    pub pagination: Setting<PaginationSettings>,

    #[serde(skip)]
    pub _kind: PhantomData<T>,
}

impl Settings<Checked> {
    pub fn cleared() -> Settings<Checked> {
        Settings {
            displayed_attributes: Setting::Reset,
            searchable_attributes: Setting::Reset,
            filterable_attributes: Setting::Reset,
            sortable_attributes: Setting::Reset,
            ranking_rules: Setting::Reset,
            stop_words: Setting::Reset,
            synonyms: Setting::Reset,
            distinct_attribute: Setting::Reset,
            typo_tolerance: Setting::Reset,
            faceting: Setting::Reset,
            pagination: Setting::Reset,
            _kind: PhantomData,
        }
    }

    pub fn into_unchecked(self) -> Settings<Unchecked> {
        let Self {
            displayed_attributes,
            searchable_attributes,
            filterable_attributes,
            sortable_attributes,
            ranking_rules,
            stop_words,
            synonyms,
            distinct_attribute,
            typo_tolerance,
            faceting,
            pagination,
            ..
        } = self;

        Settings {
            displayed_attributes,
            searchable_attributes,
            filterable_attributes,
            sortable_attributes,
            ranking_rules,
            stop_words,
            synonyms,
            distinct_attribute,
            typo_tolerance,
            faceting,
            pagination,
            _kind: PhantomData,
        }
    }
}

impl Settings<Unchecked> {
    pub fn check(self) -> Settings<Checked> {
        let displayed_attributes = match self.displayed_attributes {
            Setting::Set(fields) => {
                if fields.iter().any(|f| f == "*") {
                    Setting::Reset
                } else {
                    Setting::Set(fields)
                }
            }
            otherwise => otherwise,
        };

        let searchable_attributes = match self.searchable_attributes {
            Setting::Set(fields) => {
                if fields.iter().any(|f| f == "*") {
                    Setting::Reset
                } else {
                    Setting::Set(fields)
                }
            }
            otherwise => otherwise,
        };

        Settings {
            displayed_attributes,
            searchable_attributes,
            filterable_attributes: self.filterable_attributes,
            sortable_attributes: self.sortable_attributes,
            ranking_rules: self.ranking_rules,
            stop_words: self.stop_words,
            synonyms: self.synonyms,
            distinct_attribute: self.distinct_attribute,
            typo_tolerance: self.typo_tolerance,
            faceting: self.faceting,
            pagination: self.pagination,
            _kind: PhantomData,
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(deny_unknown_fields)]
#[serde(rename_all = "camelCase")]
pub struct Facets {
    pub level_group_size: Option<NonZeroUsize>,
    pub min_level_size: Option<NonZeroUsize>,
}

pub fn apply_settings_to_builder(
    settings: &Settings<Checked>,
    builder: &mut milli::update::Settings,
) {
    match settings.searchable_attributes {
        Setting::Set(ref names) => builder.set_searchable_fields(names.clone()),
        Setting::Reset => builder.reset_searchable_fields(),
        Setting::NotSet => (),
    }

    match settings.displayed_attributes {
        Setting::Set(ref names) => builder.set_displayed_fields(names.clone()),
        Setting::Reset => builder.reset_displayed_fields(),
        Setting::NotSet => (),
    }

    match settings.filterable_attributes {
        Setting::Set(ref facets) => {
            builder.set_filterable_fields(facets.clone().into_iter().collect())
        }
        Setting::Reset => builder.reset_filterable_fields(),
        Setting::NotSet => (),
    }

    match settings.sortable_attributes {
        Setting::Set(ref fields) => builder.set_sortable_fields(fields.iter().cloned().collect()),
        Setting::Reset => builder.reset_sortable_fields(),
        Setting::NotSet => (),
    }

    match settings.ranking_rules {
        Setting::Set(ref criteria) => builder.set_criteria(criteria.clone()),
        Setting::Reset => builder.reset_criteria(),
        Setting::NotSet => (),
    }

    match settings.stop_words {
        Setting::Set(ref stop_words) => builder.set_stop_words(stop_words.clone()),
        Setting::Reset => builder.reset_stop_words(),
        Setting::NotSet => (),
    }

    match settings.synonyms {
        Setting::Set(ref synonyms) => builder.set_synonyms(synonyms.clone().into_iter().collect()),
        Setting::Reset => builder.reset_synonyms(),
        Setting::NotSet => (),
    }

    match settings.distinct_attribute {
        Setting::Set(ref attr) => builder.set_distinct_field(attr.clone()),
        Setting::Reset => builder.reset_distinct_field(),
        Setting::NotSet => (),
    }

    match settings.typo_tolerance {
        Setting::Set(ref value) => {
            match value.enabled {
                Setting::Set(val) => builder.set_autorize_typos(val),
                Setting::Reset => builder.reset_authorize_typos(),
                Setting::NotSet => (),
            }

            match value.min_word_size_for_typos {
                Setting::Set(ref setting) => {
                    match setting.one_typo {
                        Setting::Set(val) => builder.set_min_word_len_one_typo(val),
                        Setting::Reset => builder.reset_min_word_len_one_typo(),
                        Setting::NotSet => (),
                    }
                    match setting.two_typos {
                        Setting::Set(val) => builder.set_min_word_len_two_typos(val),
                        Setting::Reset => builder.reset_min_word_len_two_typos(),
                        Setting::NotSet => (),
                    }
                }
                Setting::Reset => {
                    builder.reset_min_word_len_one_typo();
                    builder.reset_min_word_len_two_typos();
                }
                Setting::NotSet => (),
            }

            match value.disable_on_words {
                Setting::Set(ref words) => {
                    builder.set_exact_words(words.clone());
                }
                Setting::Reset => builder.reset_exact_words(),
                Setting::NotSet => (),
            }

            match value.disable_on_attributes {
                Setting::Set(ref words) => {
                    builder.set_exact_attributes(words.iter().cloned().collect())
                }
                Setting::Reset => builder.reset_exact_attributes(),
                Setting::NotSet => (),
            }
        }
        Setting::Reset => {
            // all typo settings need to be reset here.
            builder.reset_authorize_typos();
            builder.reset_min_word_len_one_typo();
            builder.reset_min_word_len_two_typos();
            builder.reset_exact_words();
            builder.reset_exact_attributes();
        }
        Setting::NotSet => (),
    }

    match settings.faceting {
        Setting::Set(ref value) => match value.max_values_per_facet {
            Setting::Set(val) => builder.set_max_values_per_facet(val),
            Setting::Reset => builder.reset_max_values_per_facet(),
            Setting::NotSet => (),
        },
        Setting::Reset => builder.reset_max_values_per_facet(),
        Setting::NotSet => (),
    }

    match settings.pagination {
        Setting::Set(ref value) => match value.max_total_hits {
            Setting::Set(val) => builder.set_pagination_max_total_hits(val),
            Setting::Reset => builder.reset_pagination_max_total_hits(),
            Setting::NotSet => (),
        },
        Setting::Reset => builder.reset_pagination_max_total_hits(),
        Setting::NotSet => (),
    }
}

#[cfg(test)]
pub(crate) mod test {
    use proptest::prelude::*;

    use super::*;

    pub(super) fn setting_strategy<T: Arbitrary + Clone>() -> impl Strategy<Value = Setting<T>> {
        prop_oneof![
            Just(Setting::NotSet),
            Just(Setting::Reset),
            any::<T>().prop_map(Setting::Set)
        ]
    }

    #[test]
    fn test_setting_check() {
        // test no changes
        let settings = Settings {
            displayed_attributes: Setting::Set(vec![String::from("hello")]),
            searchable_attributes: Setting::Set(vec![String::from("hello")]),
            filterable_attributes: Setting::NotSet,
            sortable_attributes: Setting::NotSet,
            ranking_rules: Setting::NotSet,
            stop_words: Setting::NotSet,
            synonyms: Setting::NotSet,
            distinct_attribute: Setting::NotSet,
            typo_tolerance: Setting::NotSet,
            faceting: Setting::NotSet,
            pagination: Setting::NotSet,
            _kind: PhantomData::<Unchecked>,
        };

        let checked = settings.clone().check();
        assert_eq!(settings.displayed_attributes, checked.displayed_attributes);
        assert_eq!(
            settings.searchable_attributes,
            checked.searchable_attributes
        );

        // test wildcard
        // test no changes
        let settings = Settings {
            displayed_attributes: Setting::Set(vec![String::from("*")]),
            searchable_attributes: Setting::Set(vec![String::from("hello"), String::from("*")]),
            filterable_attributes: Setting::NotSet,
            sortable_attributes: Setting::NotSet,
            ranking_rules: Setting::NotSet,
            stop_words: Setting::NotSet,
            synonyms: Setting::NotSet,
            distinct_attribute: Setting::NotSet,
            typo_tolerance: Setting::NotSet,
            faceting: Setting::NotSet,
            pagination: Setting::NotSet,
            _kind: PhantomData::<Unchecked>,
        };

        let checked = settings.check();
        assert_eq!(checked.displayed_attributes, Setting::Reset);
        assert_eq!(checked.searchable_attributes, Setting::Reset);
    }
}