use crate::query_builder::{BindCollector, MoveableBindCollector};
use crate::serialize::{IsNull, Output};
use crate::sql_types::HasSqlType;
use crate::sqlite::{Sqlite, SqliteType};
use crate::QueryResult;

#[derive(Debug, Default)]
pub struct SqliteBindCollector<'a> {
    pub(in crate::sqlite) binds: Vec<(InternalSqliteBindValue<'a>, SqliteType)>,
}

impl SqliteBindCollector<'_> {
    pub(in crate::sqlite) fn new() -> Self {
        Self { binds: Vec::new() }
    }
}

/// This type represents a value bound to
/// a sqlite prepared statement
///
/// It can be constructed via the various `From<T>` implementations
#[derive(Debug)]
pub struct SqliteBindValue<'a> {
    pub(in crate::sqlite) inner: InternalSqliteBindValue<'a>,
}

impl<'a> From<i32> for SqliteBindValue<'a> {
    fn from(i: i32) -> Self {
        Self {
            inner: InternalSqliteBindValue::I32(i),
        }
    }
}

impl<'a> From<i64> for SqliteBindValue<'a> {
    fn from(i: i64) -> Self {
        Self {
            inner: InternalSqliteBindValue::I64(i),
        }
    }
}

impl<'a> From<f64> for SqliteBindValue<'a> {
    fn from(f: f64) -> Self {
        Self {
            inner: InternalSqliteBindValue::F64(f),
        }
    }
}

impl<'a, T> From<Option<T>> for SqliteBindValue<'a>
where
    T: Into<SqliteBindValue<'a>>,
{
    fn from(o: Option<T>) -> Self {
        match o {
            Some(v) => v.into(),
            None => Self {
                inner: InternalSqliteBindValue::Null,
            },
        }
    }
}

impl<'a> From<&'a str> for SqliteBindValue<'a> {
    fn from(s: &'a str) -> Self {
        Self {
            inner: InternalSqliteBindValue::BorrowedString(s),
        }
    }
}

impl<'a> From<String> for SqliteBindValue<'a> {
    fn from(s: String) -> Self {
        Self {
            inner: InternalSqliteBindValue::String(s.into_boxed_str()),
        }
    }
}

impl<'a> From<Vec<u8>> for SqliteBindValue<'a> {
    fn from(b: Vec<u8>) -> Self {
        Self {
            inner: InternalSqliteBindValue::Binary(b.into_boxed_slice()),
        }
    }
}

impl<'a> From<&'a [u8]> for SqliteBindValue<'a> {
    fn from(b: &'a [u8]) -> Self {
        Self {
            inner: InternalSqliteBindValue::BorrowedBinary(b),
        }
    }
}

#[derive(Debug)]
pub(crate) enum InternalSqliteBindValue<'a> {
    BorrowedString(&'a str),
    String(Box<str>),
    BorrowedBinary(&'a [u8]),
    Binary(Box<[u8]>),
    I32(i32),
    I64(i64),
    F64(f64),
    Null,
}

impl std::fmt::Display for InternalSqliteBindValue<'_> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let n = match self {
            InternalSqliteBindValue::BorrowedString(_) | InternalSqliteBindValue::String(_) => {
                "Text"
            }
            InternalSqliteBindValue::BorrowedBinary(_) | InternalSqliteBindValue::Binary(_) => {
                "Binary"
            }
            InternalSqliteBindValue::I32(_) | InternalSqliteBindValue::I64(_) => "Integer",
            InternalSqliteBindValue::F64(_) => "Float",
            InternalSqliteBindValue::Null => "Null",
        };
        f.write_str(n)
    }
}

impl InternalSqliteBindValue<'_> {
    #[allow(unsafe_code)] // ffi function calls
    pub(in crate::sqlite) fn result_of(
        self,
        ctx: &mut libsqlite3_sys::sqlite3_context,
    ) -> Result<(), std::num::TryFromIntError> {
        use libsqlite3_sys as ffi;
        use std::os::raw as libc;
        // This unsafe block assumes the following invariants:
        //
        // - `ctx` points to valid memory
        unsafe {
            match self {
                InternalSqliteBindValue::BorrowedString(s) => ffi::sqlite3_result_text(
                    ctx,
                    s.as_ptr() as *const libc::c_char,
                    s.len().try_into()?,
                    ffi::SQLITE_TRANSIENT(),
                ),
                InternalSqliteBindValue::String(s) => ffi::sqlite3_result_text(
                    ctx,
                    s.as_ptr() as *const libc::c_char,
                    s.len().try_into()?,
                    ffi::SQLITE_TRANSIENT(),
                ),
                InternalSqliteBindValue::Binary(b) => ffi::sqlite3_result_blob(
                    ctx,
                    b.as_ptr() as *const libc::c_void,
                    b.len().try_into()?,
                    ffi::SQLITE_TRANSIENT(),
                ),
                InternalSqliteBindValue::BorrowedBinary(b) => ffi::sqlite3_result_blob(
                    ctx,
                    b.as_ptr() as *const libc::c_void,
                    b.len().try_into()?,
                    ffi::SQLITE_TRANSIENT(),
                ),
                InternalSqliteBindValue::I32(i) => ffi::sqlite3_result_int(ctx, i as libc::c_int),
                InternalSqliteBindValue::I64(l) => ffi::sqlite3_result_int64(ctx, l),
                InternalSqliteBindValue::F64(d) => {
                    ffi::sqlite3_result_double(ctx, d as libc::c_double)
                }
                InternalSqliteBindValue::Null => ffi::sqlite3_result_null(ctx),
            }
        }
        Ok(())
    }
}

impl<'a> BindCollector<'a, Sqlite> for SqliteBindCollector<'a> {
    type Buffer = SqliteBindValue<'a>;

    fn push_bound_value<T, U>(&mut self, bind: &'a U, metadata_lookup: &mut ()) -> QueryResult<()>
    where
        Sqlite: crate::sql_types::HasSqlType<T>,
        U: crate::serialize::ToSql<T, Sqlite> + ?Sized,
    {
        let value = SqliteBindValue {
            inner: InternalSqliteBindValue::Null,
        };
        let mut to_sql_output = Output::new(value, metadata_lookup);
        let is_null = bind
            .to_sql(&mut to_sql_output)
            .map_err(crate::result::Error::SerializationError)?;
        let bind = to_sql_output.into_inner();
        let metadata = Sqlite::metadata(metadata_lookup);
        self.binds.push((
            match is_null {
                IsNull::No => bind.inner,
                IsNull::Yes => InternalSqliteBindValue::Null,
            },
            metadata,
        ));
        Ok(())
    }

    fn push_null_value(&mut self, metadata: SqliteType) -> QueryResult<()> {
        self.binds.push((InternalSqliteBindValue::Null, metadata));
        Ok(())
    }
}

#[derive(Debug)]
enum OwnedSqliteBindValue {
    String(Box<str>),
    Binary(Box<[u8]>),
    I32(i32),
    I64(i64),
    F64(f64),
    Null,
}

impl<'a> std::convert::From<&InternalSqliteBindValue<'a>> for OwnedSqliteBindValue {
    fn from(value: &InternalSqliteBindValue<'a>) -> Self {
        match value {
            InternalSqliteBindValue::String(s) => Self::String(s.clone()),
            InternalSqliteBindValue::BorrowedString(s) => {
                Self::String(String::from(*s).into_boxed_str())
            }
            InternalSqliteBindValue::Binary(b) => Self::Binary(b.clone()),
            InternalSqliteBindValue::BorrowedBinary(s) => {
                Self::Binary(Vec::from(*s).into_boxed_slice())
            }
            InternalSqliteBindValue::I32(val) => Self::I32(*val),
            InternalSqliteBindValue::I64(val) => Self::I64(*val),
            InternalSqliteBindValue::F64(val) => Self::F64(*val),
            InternalSqliteBindValue::Null => Self::Null,
        }
    }
}

impl<'a> std::convert::From<&OwnedSqliteBindValue> for InternalSqliteBindValue<'a> {
    fn from(value: &OwnedSqliteBindValue) -> Self {
        match value {
            OwnedSqliteBindValue::String(s) => Self::String(s.clone()),
            OwnedSqliteBindValue::Binary(b) => Self::Binary(b.clone()),
            OwnedSqliteBindValue::I32(val) => Self::I32(*val),
            OwnedSqliteBindValue::I64(val) => Self::I64(*val),
            OwnedSqliteBindValue::F64(val) => Self::F64(*val),
            OwnedSqliteBindValue::Null => Self::Null,
        }
    }
}

#[derive(Debug)]
/// Sqlite bind collector data that is movable across threads
pub struct SqliteBindCollectorData {
    binds: Vec<(OwnedSqliteBindValue, SqliteType)>,
}

impl MoveableBindCollector<Sqlite> for SqliteBindCollector<'_> {
    type BindData = SqliteBindCollectorData;

    fn moveable(&self) -> Self::BindData {
        let mut binds = Vec::with_capacity(self.binds.len());
        for b in self
            .binds
            .iter()
            .map(|(bind, tpe)| (OwnedSqliteBindValue::from(bind), *tpe))
        {
            binds.push(b);
        }
        SqliteBindCollectorData { binds }
    }

    fn append_bind_data(&mut self, from: &Self::BindData) {
        self.binds.reserve_exact(from.binds.len());
        self.binds.extend(
            from.binds
                .iter()
                .map(|(bind, tpe)| (InternalSqliteBindValue::from(bind), *tpe)),
        );
    }
}