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use crate::decode::Decode;
use crate::encode::{Encode, IsNull};
use crate::error::BoxDynError;
use crate::mssql::io::MssqlBufMutExt;
use crate::mssql::protocol::type_info::{Collation, CollationFlags, DataType, TypeInfo};
use crate::mssql::{Mssql, MssqlTypeInfo, MssqlValueRef};
use crate::types::Type;
use std::borrow::Cow;

impl Type<Mssql> for str {
    fn type_info() -> MssqlTypeInfo {
        MssqlTypeInfo(TypeInfo::new(DataType::NVarChar, 0))
    }

    fn compatible(ty: &MssqlTypeInfo) -> bool {
        matches!(
            ty.0.ty,
            DataType::NVarChar
                | DataType::NChar
                | DataType::BigVarChar
                | DataType::VarChar
                | DataType::BigChar
                | DataType::Char
        )
    }
}

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

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

impl Encode<'_, Mssql> for &'_ str {
    fn produces(&self) -> Option<MssqlTypeInfo> {
        // an empty string needs to be encoded as `nvarchar(2)`
        Some(MssqlTypeInfo(TypeInfo {
            ty: DataType::NVarChar,
            size: ((self.len() * 2) as u32).max(2),
            scale: 0,
            precision: 0,
            collation: Some(Collation {
                locale: 1033,
                flags: CollationFlags::IGNORE_CASE
                    | CollationFlags::IGNORE_WIDTH
                    | CollationFlags::IGNORE_KANA,
                sort: 52,
                version: 0,
            }),
        }))
    }

    fn encode_by_ref(&self, buf: &mut Vec<u8>) -> IsNull {
        buf.put_utf16_str(self);

        IsNull::No
    }
}

impl Encode<'_, Mssql> for String {
    fn produces(&self) -> Option<MssqlTypeInfo> {
        <&str as Encode<Mssql>>::produces(&self.as_str())
    }

    fn encode_by_ref(&self, buf: &mut Vec<u8>) -> IsNull {
        <&str as Encode<Mssql>>::encode_by_ref(&self.as_str(), buf)
    }
}

impl Decode<'_, Mssql> for String {
    fn decode(value: MssqlValueRef<'_>) -> Result<Self, BoxDynError> {
        Ok(value
            .type_info
            .0
            .encoding()?
            .decode_without_bom_handling(value.as_bytes()?)
            .0
            .into_owned())
    }
}

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

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

impl Encode<'_, Mssql> for Cow<'_, str> {
    fn produces(&self) -> Option<MssqlTypeInfo> {
        match self {
            Cow::Borrowed(str) => <&str as Encode<Mssql>>::produces(str),
            Cow::Owned(str) => <&str as Encode<Mssql>>::produces(&(str.as_ref())),
        }
    }

    fn encode_by_ref(&self, buf: &mut Vec<u8>) -> IsNull {
        match self {
            Cow::Borrowed(str) => <&str as Encode<Mssql>>::encode_by_ref(str, buf),
            Cow::Owned(str) => <&str as Encode<Mssql>>::encode_by_ref(&(str.as_ref()), buf),
        }
    }
}

impl<'r> Decode<'r, Mssql> for Cow<'r, str> {
    fn decode(value: MssqlValueRef<'r>) -> Result<Self, BoxDynError> {
        Ok(Cow::Owned(
            value
                .type_info
                .0
                .encoding()?
                .decode_without_bom_handling(value.as_bytes()?)
                .0
                .into_owned(),
        ))
    }
}