use std::fmt;
use std::str::FromStr;

use serde::{Deserialize, Serialize};

use crate::error::{is_reserved_keyword, Error, UserError};

#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq)]
pub enum Criterion {
    /// Sorted by decreasing number of matched query terms.
    /// Query words at the front of an attribute is considered better than if it was at the back.
    Words,
    /// Sorted by increasing number of typos.
    Typo,
    /// Sorted by increasing distance between matched query terms.
    Proximity,
    /// Documents with quey words contained in more important
    /// attributes are considered better.
    Attribute,
    /// Dynamically sort at query time the documents. None, one or multiple Asc/Desc sortable
    /// attributes can be used in place of this criterion at query time.
    Sort,
    /// Sorted by the similarity of the matched words with the query words.
    Exactness,
    /// Sorted by the increasing value of the field specified.
    Asc(String),
    /// Sorted by the decreasing value of the field specified.
    Desc(String),
}

impl Criterion {
    /// Returns the field name parameter of this criterion.
    pub fn field_name(&self) -> Option<&str> {
        match self {
            Criterion::Asc(name) | Criterion::Desc(name) => Some(name),
            _otherwise => None,
        }
    }
}

impl FromStr for Criterion {
    type Err = Error;

    fn from_str(text: &str) -> Result<Criterion, Self::Err> {
        match text {
            "words" => Ok(Criterion::Words),
            "typo" => Ok(Criterion::Typo),
            "proximity" => Ok(Criterion::Proximity),
            "attribute" => Ok(Criterion::Attribute),
            "sort" => Ok(Criterion::Sort),
            "exactness" => Ok(Criterion::Exactness),
            text => match AscDesc::from_str(text) {
                Ok(AscDesc::Asc(Member::Field(field))) => Ok(Criterion::Asc(field)),
                Ok(AscDesc::Desc(Member::Field(field))) => Ok(Criterion::Desc(field)),
                Ok(AscDesc::Asc(Member::Geo(_))) | Ok(AscDesc::Desc(Member::Geo(_))) => {
                    Err(UserError::InvalidReservedRankingRuleNameSort {
                        name: "_geoPoint".to_string(),
                    })?
                }
                Err(UserError::InvalidAscDescSyntax { name }) => {
                    Err(UserError::InvalidRankingRuleName { name })?
                }
                Err(UserError::InvalidReservedAscDescSyntax { name })
                    if name.starts_with("_geoPoint") =>
                {
                    Err(UserError::InvalidReservedRankingRuleNameSort {
                        name: "_geoPoint".to_string(),
                    }
                    .into())
                }
                Err(UserError::InvalidReservedAscDescSyntax { name })
                    if name.starts_with("_geoRadius") =>
                {
                    Err(UserError::InvalidReservedRankingRuleNameFilter {
                        name: "_geoRadius".to_string(),
                    }
                    .into())
                }
                Err(UserError::InvalidReservedAscDescSyntax { name }) => {
                    Err(UserError::InvalidReservedRankingRuleName { name }.into())
                }
                Err(error) => {
                    Err(UserError::InvalidRankingRuleName { name: error.to_string() }.into())
                }
            },
        }
    }
}

#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
pub enum Member {
    Field(String),
    Geo([f64; 2]),
}

impl FromStr for Member {
    type Err = UserError;

    fn from_str(text: &str) -> Result<Member, Self::Err> {
        match text.strip_prefix("_geoPoint(").and_then(|text| text.strip_suffix(")")) {
            Some(point) => {
                let (lat, long) = point
                    .split_once(',')
                    .ok_or_else(|| UserError::InvalidReservedAscDescSyntax {
                        name: text.to_string(),
                    })
                    .and_then(|(lat, long)| {
                        lat.trim()
                            .parse()
                            .and_then(|lat| long.trim().parse().map(|long| (lat, long)))
                            .map_err(|_| UserError::InvalidReservedAscDescSyntax {
                                name: text.to_string(),
                            })
                    })?;
                Ok(Member::Geo([lat, long]))
            }
            None => {
                if is_reserved_keyword(text) || text.starts_with("_geoRadius(") {
                    return Err(UserError::InvalidReservedAscDescSyntax {
                        name: text.to_string(),
                    })?;
                }
                Ok(Member::Field(text.to_string()))
            }
        }
    }
}

impl fmt::Display for Member {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Member::Field(name) => f.write_str(name),
            Member::Geo([lat, lng]) => write!(f, "_geoPoint({}, {})", lat, lng),
        }
    }
}

impl Member {
    pub fn field(&self) -> Option<&str> {
        match self {
            Member::Field(field) => Some(field),
            Member::Geo(_) => None,
        }
    }

    pub fn geo_point(&self) -> Option<&[f64; 2]> {
        match self {
            Member::Geo(point) => Some(point),
            Member::Field(_) => None,
        }
    }
}

#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
pub enum AscDesc {
    Asc(Member),
    Desc(Member),
}

impl AscDesc {
    pub fn member(&self) -> &Member {
        match self {
            AscDesc::Asc(member) => member,
            AscDesc::Desc(member) => member,
        }
    }

    pub fn field(&self) -> Option<&str> {
        self.member().field()
    }
}

impl FromStr for AscDesc {
    type Err = UserError;

    /// Since we don't know if this was deserialized for a criterion or a sort we just return a
    /// string and let the caller create his own error
    fn from_str(text: &str) -> Result<AscDesc, Self::Err> {
        match text.rsplit_once(':') {
            Some((left, "asc")) => Ok(AscDesc::Asc(left.parse()?)),
            Some((left, "desc")) => Ok(AscDesc::Desc(left.parse()?)),
            _ => Err(UserError::InvalidAscDescSyntax { name: text.to_string() }),
        }
    }
}

pub fn default_criteria() -> Vec<Criterion> {
    vec![
        Criterion::Words,
        Criterion::Typo,
        Criterion::Proximity,
        Criterion::Attribute,
        Criterion::Sort,
        Criterion::Exactness,
    ]
}

impl fmt::Display for Criterion {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        use Criterion::*;

        match self {
            Words => f.write_str("words"),
            Typo => f.write_str("typo"),
            Proximity => f.write_str("proximity"),
            Attribute => f.write_str("attribute"),
            Sort => f.write_str("sort"),
            Exactness => f.write_str("exactness"),
            Asc(attr) => write!(f, "{}:asc", attr),
            Desc(attr) => write!(f, "{}:desc", attr),
        }
    }
}

#[cfg(test)]
mod tests {
    use big_s::S;
    use AscDesc::*;
    use Member::*;
    use UserError::*;

    use super::*;

    #[test]
    fn parse_asc_desc() {
        let valid_req = [
            ("truc:asc", Asc(Field(S("truc")))),
            ("bidule:desc", Desc(Field(S("bidule")))),
            ("a-b:desc", Desc(Field(S("a-b")))),
            ("a:b:desc", Desc(Field(S("a:b")))),
            ("a12:asc", Asc(Field(S("a12")))),
            ("42:asc", Asc(Field(S("42")))),
            ("_geoPoint(42, 59):asc", Asc(Geo([42., 59.]))),
            ("_geoPoint(42.459, 59):desc", Desc(Geo([42.459, 59.]))),
            ("_geoPoint(42, 59.895):desc", Desc(Geo([42., 59.895]))),
            ("_geoPoint(42, 59.895):desc", Desc(Geo([42., 59.895]))),
            ("_geoPoint(42.0002, 59.895):desc", Desc(Geo([42.0002, 59.895]))),
            ("_geoPoint(42., 59.):desc", Desc(Geo([42., 59.]))),
            ("truc(12, 13):desc", Desc(Field(S("truc(12, 13)")))),
        ];

        for (req, expected) in valid_req {
            let res = req.parse::<AscDesc>();
            assert!(
                res.is_ok(),
                "Failed to parse `{}`, was expecting `{:?}` but instead got `{:?}`",
                req,
                expected,
                res
            );
            assert_eq!(res.unwrap(), expected);
        }

        let invalid_req = [
            ("truc:machin", InvalidAscDescSyntax { name: S("truc:machin") }),
            ("truc:deesc", InvalidAscDescSyntax { name: S("truc:deesc") }),
            ("truc:asc:deesc", InvalidAscDescSyntax { name: S("truc:asc:deesc") }),
            ("42desc", InvalidAscDescSyntax { name: S("42desc") }),
            ("_geoPoint:asc", InvalidReservedAscDescSyntax { name: S("_geoPoint") }),
            ("_geoDistance:asc", InvalidReservedAscDescSyntax { name: S("_geoDistance") }),
            (
                "_geoPoint(42.12 , 59.598)",
                InvalidAscDescSyntax { name: S("_geoPoint(42.12 , 59.598)") },
            ),
            (
                "_geoPoint(42.12 , 59.598):deesc",
                InvalidAscDescSyntax { name: S("_geoPoint(42.12 , 59.598):deesc") },
            ),
            (
                "_geoPoint(42.12 , 59.598):machin",
                InvalidAscDescSyntax { name: S("_geoPoint(42.12 , 59.598):machin") },
            ),
            (
                "_geoPoint(42.12 , 59.598):asc:aasc",
                InvalidAscDescSyntax { name: S("_geoPoint(42.12 , 59.598):asc:aasc") },
            ),
            (
                "_geoPoint(42,12 , 59,598):desc",
                InvalidReservedAscDescSyntax { name: S("_geoPoint(42,12 , 59,598)") },
            ),
            (
                "_geoPoint(35, 85, 75):asc",
                InvalidReservedAscDescSyntax { name: S("_geoPoint(35, 85, 75)") },
            ),
            ("_geoPoint(18):asc", InvalidReservedAscDescSyntax { name: S("_geoPoint(18)") }),
        ];

        for (req, expected_error) in invalid_req {
            let res = req.parse::<AscDesc>();
            assert!(
                res.is_err(),
                "Should no be able to parse `{}`, was expecting an error but instead got: `{:?}`",
                req,
                res,
            );
            let res = res.unwrap_err();
            assert_eq!(
                res.to_string(),
                expected_error.to_string(),
                "Bad error for input {}: got `{:?}` instead of `{:?}`",
                req,
                res,
                expected_error
            );
        }
    }

    #[test]
    fn parse_criterion() {
        let valid_criteria = [
            ("words", Criterion::Words),
            ("typo", Criterion::Typo),
            ("proximity", Criterion::Proximity),
            ("attribute", Criterion::Attribute),
            ("sort", Criterion::Sort),
            ("exactness", Criterion::Exactness),
            ("price:asc", Criterion::Asc(S("price"))),
            ("price:desc", Criterion::Desc(S("price"))),
            ("price:asc:desc", Criterion::Desc(S("price:asc"))),
            ("truc:machin:desc", Criterion::Desc(S("truc:machin"))),
            ("hello-world!:desc", Criterion::Desc(S("hello-world!"))),
            ("it's spacy over there:asc", Criterion::Asc(S("it's spacy over there"))),
        ];

        for (input, expected) in valid_criteria {
            let res = input.parse::<Criterion>();
            assert!(
                res.is_ok(),
                "Failed to parse `{}`, was expecting `{:?}` but instead got `{:?}`",
                input,
                expected,
                res
            );
            assert_eq!(res.unwrap(), expected);
        }

        let invalid_criteria = [
            ("words suffix", InvalidRankingRuleName { name: S("words suffix") }),
            ("prefix typo", InvalidRankingRuleName { name: S("prefix typo") }),
            ("proximity attribute", InvalidRankingRuleName { name: S("proximity attribute") }),
            ("price", InvalidRankingRuleName { name: S("price") }),
            ("asc:price", InvalidRankingRuleName { name: S("asc:price") }),
            ("price:deesc", InvalidRankingRuleName { name: S("price:deesc") }),
            ("price:aasc", InvalidRankingRuleName { name: S("price:aasc") }),
            ("price:asc and desc", InvalidRankingRuleName { name: S("price:asc and desc") }),
            ("price:asc:truc", InvalidRankingRuleName { name: S("price:asc:truc") }),
            ("_geo:asc", InvalidReservedRankingRuleName { name: S("_geo") }),
            ("_geoDistance:asc", InvalidReservedRankingRuleName { name: S("_geoDistance") }),
            ("_geoPoint:asc", InvalidReservedRankingRuleNameSort { name: S("_geoPoint") }),
            ("_geoPoint(42, 75):asc", InvalidReservedRankingRuleNameSort { name: S("_geoPoint") }),
            ("_geoRadius:asc", InvalidReservedRankingRuleNameFilter { name: S("_geoRadius") }),
            (
                "_geoRadius(42, 75, 59):asc",
                InvalidReservedRankingRuleNameFilter { name: S("_geoRadius") },
            ),
        ];

        for (input, expected) in invalid_criteria {
            let res = input.parse::<Criterion>();
            assert!(
                res.is_err(),
                "Should no be able to parse `{}`, was expecting an error but instead got: `{:?}`",
                input,
                res
            );
            let res = res.unwrap_err();
            assert_eq!(
                res.to_string(),
                expected.to_string(),
                "Bad error for input {}: got `{:?}` instead of `{:?}`",
                input,
                res,
                expected
            );
        }
    }
}