use crate::{
    new_input,
    utils::{spanned, str_parser},
    Error, Input, Result, TypeStem,
};
use alloc::vec::Vec;
use core::num::NonZeroUsize;
use winnow::{
    ascii::digit0,
    combinator::{cut_err, delimited, repeat, trace},
    error::{ErrMode, ErrorKind, FromExternalError},
    PResult, Parser,
};

/// Represents a type-name. Consists of an identifier and optional array sizes.
///
/// A type specifier has a stem, which is [`TypeStem`] representing either a
/// [`RootType`] or a [`TupleSpecifier`], and a list of array sizes. The array
/// sizes are in innermost-to-outermost order. An empty array size vec indicates
/// that the specified type is not an array
///
/// Type specifier examples:
/// - `uint256`
/// - `uint256[2]`
/// - `uint256[2][]`
/// - `(uint256,uint256)`
/// - `(uint256,uint256)[2]`
/// - `MyStruct`
/// - `MyStruct[2]`
///
/// <https://docs.soliditylang.org/en/latest/grammar.html#a4.SolidityParser.typeName>
///
/// [`RootType`]: crate::RootType
/// [`TupleSpecifier`]: crate::TupleSpecifier
///
/// ## Compatibility with JSON ABI
///
/// This type supports the `internalType` semantics for JSON-ABI compatibility.
///
/// Examples of valid JSON ABI internal types:
/// - `contract MyContract`
/// - `struct MyStruct`
/// - `enum MyEnum`
/// - `struct MyContract.MyStruct\[333\]`
/// - `enum MyContract.MyEnum[][][][][][]`
/// - `MyValueType`
///
/// # Examples
///
/// ```
/// # use alloy_sol_type_parser::TypeSpecifier;
/// # use core::num::NonZeroUsize;
/// let spec = TypeSpecifier::parse("uint256[2][]")?;
/// assert_eq!(spec.span(), "uint256[2][]");
/// assert_eq!(spec.stem.span(), "uint256");
/// // The sizes are in innermost-to-outermost order.
/// assert_eq!(spec.sizes.as_slice(), &[NonZeroUsize::new(2), None]);
/// # Ok::<_, alloy_sol_type_parser::Error>(())
/// ```
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct TypeSpecifier<'a> {
    /// The full span of the specifier.
    pub span: &'a str,
    /// The type stem, which is either a root type or a tuple type.
    pub stem: TypeStem<'a>,
    /// Array sizes, in innermost-to-outermost order. If the size is `None`,
    /// then the array is dynamic. If the size is `Some`, then the array is
    /// fixed-size. If the vec is empty, then the type is not an array.
    pub sizes: Vec<Option<NonZeroUsize>>,
}

impl<'a> TryFrom<&'a str> for TypeSpecifier<'a> {
    type Error = Error;

    #[inline]
    fn try_from(s: &'a str) -> Result<Self> {
        Self::parse(s)
    }
}

impl AsRef<str> for TypeSpecifier<'_> {
    #[inline]
    fn as_ref(&self) -> &str {
        self.span()
    }
}

impl<'a> TypeSpecifier<'a> {
    /// Parse a type specifier from a string.
    #[inline]
    pub fn parse(s: &'a str) -> Result<Self> {
        Self::parser.parse(new_input(s)).map_err(Error::parser)
    }

    /// [`winnow`] parser for this type.
    pub(crate) fn parser(input: &mut Input<'a>) -> PResult<Self> {
        trace(
            "TypeSpecifier",
            spanned(|input: &mut Input<'a>| {
                let stem = TypeStem::parser(input)?;
                let sizes = if input.starts_with('[') {
                    repeat(
                        1..,
                        delimited(str_parser("["), array_size_parser, cut_err(str_parser("]"))),
                    )
                    .parse_next(input)?
                } else {
                    Vec::new()
                };
                Ok((stem, sizes))
            }),
        )
        .parse_next(input)
        .map(|(span, (stem, sizes))| Self { span, stem, sizes })
    }

    /// Returns the type stem as a string.
    #[inline]
    pub const fn span(&self) -> &'a str {
        self.span
    }

    /// Returns the type stem.
    #[inline]
    pub const fn stem(&self) -> &TypeStem<'_> {
        &self.stem
    }

    /// Returns true if the type is a basic Solidity type.
    #[inline]
    pub fn try_basic_solidity(&self) -> Result<()> {
        self.stem.try_basic_solidity()
    }

    /// Returns true if this type is an array.
    #[inline]
    pub fn is_array(&self) -> bool {
        !self.sizes.is_empty()
    }
}

fn array_size_parser(input: &mut Input<'_>) -> PResult<Option<NonZeroUsize>> {
    let digits = digit0(input)?;
    if digits.is_empty() {
        return Ok(None);
    }
    digits.parse().map(Some).map_err(|e| ErrMode::from_external_error(input, ErrorKind::Verify, e))
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::TupleSpecifier;
    use alloc::string::ToString;

    #[track_caller]
    fn assert_error_contains(e: &Error, s: &str) {
        if cfg!(feature = "std") {
            let es = e.to_string();
            assert!(es.contains(s), "{s:?} not in {es:?}");
        }
    }

    #[test]
    fn parse_test() {
        assert_eq!(
            TypeSpecifier::parse("uint"),
            Ok(TypeSpecifier {
                span: "uint",
                stem: TypeStem::parse("uint256").unwrap(),
                sizes: vec![],
            })
        );

        assert_eq!(
            TypeSpecifier::parse("uint256"),
            Ok(TypeSpecifier {
                span: "uint256",
                stem: TypeStem::parse("uint256").unwrap(),
                sizes: vec![],
            })
        );

        assert_eq!(
            TypeSpecifier::parse("uint256[2]"),
            Ok(TypeSpecifier {
                span: "uint256[2]",
                stem: TypeStem::parse("uint256").unwrap(),
                sizes: vec![NonZeroUsize::new(2)],
            })
        );

        assert_eq!(
            TypeSpecifier::parse("uint256[2][]"),
            Ok(TypeSpecifier {
                span: "uint256[2][]",
                stem: TypeStem::parse("uint256").unwrap(),
                sizes: vec![NonZeroUsize::new(2), None],
            })
        );

        assert_eq!(
            TypeSpecifier::parse("(uint256,uint256)"),
            Ok(TypeSpecifier {
                span: "(uint256,uint256)",
                stem: TypeStem::Tuple(TupleSpecifier::parse("(uint256,uint256)").unwrap()),
                sizes: vec![],
            })
        );

        assert_eq!(
            TypeSpecifier::parse("(uint256,uint256)[2]"),
            Ok(TypeSpecifier {
                span: "(uint256,uint256)[2]",
                stem: TypeStem::Tuple(TupleSpecifier::parse("(uint256,uint256)").unwrap()),
                sizes: vec![NonZeroUsize::new(2)],
            })
        );

        assert_eq!(
            TypeSpecifier::parse("MyStruct"),
            Ok(TypeSpecifier {
                span: "MyStruct",
                stem: TypeStem::parse("MyStruct").unwrap(),
                sizes: vec![],
            })
        );

        assert_eq!(
            TypeSpecifier::parse("MyStruct[2]"),
            Ok(TypeSpecifier {
                span: "MyStruct[2]",
                stem: TypeStem::parse("MyStruct").unwrap(),
                sizes: vec![NonZeroUsize::new(2)],
            })
        );
    }

    #[test]
    fn sizes() {
        TypeSpecifier::parse("a[").unwrap_err();
        TypeSpecifier::parse("a[][").unwrap_err();

        assert_eq!(
            TypeSpecifier::parse("a[]"),
            Ok(TypeSpecifier {
                span: "a[]",
                stem: TypeStem::parse("a").unwrap(),
                sizes: vec![None],
            }),
        );

        assert_eq!(
            TypeSpecifier::parse("a[1]"),
            Ok(TypeSpecifier {
                span: "a[1]",
                stem: TypeStem::parse("a").unwrap(),
                sizes: vec![NonZeroUsize::new(1)],
            }),
        );

        let e = TypeSpecifier::parse("a[0]").unwrap_err();
        assert_error_contains(&e, "number would be zero for non-zero type");
        TypeSpecifier::parse("a[x]").unwrap_err();

        TypeSpecifier::parse("a[ ]").unwrap_err();
        TypeSpecifier::parse("a[  ]").unwrap_err();
        TypeSpecifier::parse("a[ 0]").unwrap_err();
        TypeSpecifier::parse("a[0 ]").unwrap_err();

        TypeSpecifier::parse("a[a]").unwrap_err();
        TypeSpecifier::parse("a[ a]").unwrap_err();
        TypeSpecifier::parse("a[a ]").unwrap_err();

        TypeSpecifier::parse("a[ 1]").unwrap_err();
        TypeSpecifier::parse("a[1 ]").unwrap_err();

        TypeSpecifier::parse(&format!("a[{}]", usize::MAX)).unwrap();
        let e = TypeSpecifier::parse(&format!("a[{}0]", usize::MAX)).unwrap_err();
        assert_error_contains(&e, "number too large to fit in target type");
    }

    #[test]
    fn try_basic_solidity() {
        assert_eq!(TypeSpecifier::parse("uint").unwrap().try_basic_solidity(), Ok(()));
        assert_eq!(TypeSpecifier::parse("int").unwrap().try_basic_solidity(), Ok(()));
        assert_eq!(TypeSpecifier::parse("uint256").unwrap().try_basic_solidity(), Ok(()));
        assert_eq!(TypeSpecifier::parse("uint256[]").unwrap().try_basic_solidity(), Ok(()));
        assert_eq!(TypeSpecifier::parse("(uint256,uint256)").unwrap().try_basic_solidity(), Ok(()));
        assert_eq!(
            TypeSpecifier::parse("(uint256,uint256)[2]").unwrap().try_basic_solidity(),
            Ok(())
        );
        assert_eq!(
            TypeSpecifier::parse("tuple(uint256,uint256)").unwrap().try_basic_solidity(),
            Ok(())
        );
        assert_eq!(
            TypeSpecifier::parse("tuple(address,bytes,(bool,(string,uint256)[][3]))[2]")
                .unwrap()
                .try_basic_solidity(),
            Ok(())
        );
    }

    #[test]
    fn not_basic_solidity() {
        assert_eq!(
            TypeSpecifier::parse("MyStruct").unwrap().try_basic_solidity(),
            Err(Error::invalid_type_string("MyStruct"))
        );
    }
}