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use std::borrow::Cow;

use serde::Deserialize;
use sqlx_core::{
    decode::Decode,
    encode::{Encode, IsNull},
    error::BoxDynError,
    types::Type,
};

use crate::{
    arguments::ExaBuffer,
    database::Exasol,
    type_info::{Charset, ExaDataType, ExaTypeInfo, StringLike},
    value::ExaValueRef,
};

impl Type<Exasol> for str {
    fn type_info() -> ExaTypeInfo {
        let string_like = StringLike::new(StringLike::MAX_VARCHAR_LEN, Charset::Utf8);
        ExaDataType::Varchar(string_like).into()
    }

    fn compatible(ty: &ExaTypeInfo) -> bool {
        <Self as Type<Exasol>>::type_info().compatible(ty)
    }
}

impl Encode<'_, Exasol> for &'_ str {
    fn encode_by_ref(&self, buf: &mut ExaBuffer) -> Result<IsNull, BoxDynError> {
        // Exasol treats empty strings as NULL
        if self.is_empty() {
            buf.append(())?;
            return Ok(IsNull::Yes);
        }

        buf.append(self)?;
        Ok(IsNull::No)
    }

    fn produces(&self) -> Option<ExaTypeInfo> {
        Some(<Self as Type<Exasol>>::type_info())
    }

    fn size_hint(&self) -> usize {
        // 2 Quotes + length
        2 + self.len()
    }
}

impl<'r> Decode<'r, Exasol> for &'r str {
    fn decode(value: ExaValueRef<'r>) -> Result<Self, BoxDynError> {
        <&str>::deserialize(value.value).map_err(From::from)
    }
}

impl Type<Exasol> for String {
    fn type_info() -> ExaTypeInfo {
        <str as Type<Exasol>>::type_info()
    }

    fn compatible(ty: &ExaTypeInfo) -> bool {
        <str as Type<Exasol>>::compatible(ty)
    }
}

impl Encode<'_, Exasol> for String {
    fn encode_by_ref(&self, buf: &mut ExaBuffer) -> Result<IsNull, BoxDynError> {
        <&str as Encode<Exasol>>::encode(&**self, buf)
    }

    fn produces(&self) -> Option<ExaTypeInfo> {
        <&str as Encode<Exasol>>::produces(&&**self)
    }

    fn size_hint(&self) -> usize {
        <&str as Encode<Exasol>>::size_hint(&&**self)
    }
}

impl Decode<'_, Exasol> for String {
    fn decode(value: ExaValueRef<'_>) -> Result<Self, BoxDynError> {
        <&str as Decode<Exasol>>::decode(value).map(ToOwned::to_owned)
    }
}

impl Type<Exasol> for Cow<'_, str> {
    fn type_info() -> ExaTypeInfo {
        <&str as Type<Exasol>>::type_info()
    }

    fn compatible(ty: &ExaTypeInfo) -> bool {
        <&str as Type<Exasol>>::compatible(ty)
    }
}

impl Encode<'_, Exasol> for Cow<'_, str> {
    fn encode_by_ref(&self, buf: &mut ExaBuffer) -> Result<IsNull, BoxDynError> {
        match self {
            Cow::Borrowed(str) => <&str as Encode<Exasol>>::encode(*str, buf),
            Cow::Owned(str) => <&str as Encode<Exasol>>::encode(&**str, buf),
        }
    }

    fn produces(&self) -> Option<ExaTypeInfo> {
        <&str as Encode<Exasol>>::produces(&&**self)
    }

    fn size_hint(&self) -> usize {
        <&str as Encode<Exasol>>::size_hint(&&**self)
    }
}

impl<'r> Decode<'r, Exasol> for Cow<'r, str> {
    fn decode(value: ExaValueRef<'r>) -> Result<Self, BoxDynError> {
        Cow::deserialize(value.value).map_err(From::from)
    }
}