use super::ExpCtxt;
use crate::verbatim::Verbatim;
use alloy_json_abi::{
    Constructor, Error, Event, EventParam, Fallback, Function, Param, Receive, StateMutability,
};
use ast::{ItemError, ItemEvent, ItemFunction};
use proc_macro2::TokenStream;
use std::fmt::Write;

pub(crate) fn generate<T>(t: &T, cx: &ExpCtxt<'_>) -> TokenStream
where
    T: ToAbi,
    T::DynAbi: Verbatim,
{
    crate::verbatim::verbatim(&t.to_dyn_abi(cx), &cx.crates)
}

pub(crate) trait ToAbi {
    type DynAbi;

    fn to_dyn_abi(&self, cx: &ExpCtxt<'_>) -> Self::DynAbi;
}

impl ToAbi for ast::ItemFunction {
    type DynAbi = Function;

    fn to_dyn_abi(&self, cx: &ExpCtxt<'_>) -> Self::DynAbi {
        Function {
            name: self.name.as_ref().map(|i| i.as_string()).unwrap_or_default(),
            inputs: self.parameters.to_dyn_abi(cx),
            outputs: self.returns.as_ref().map(|r| r.returns.to_dyn_abi(cx)).unwrap_or_default(),
            state_mutability: self.attributes.to_dyn_abi(cx),
        }
    }
}

impl ToAbi for ast::ItemError {
    type DynAbi = Error;

    fn to_dyn_abi(&self, cx: &ExpCtxt<'_>) -> Self::DynAbi {
        Error { name: self.name.as_string(), inputs: self.parameters.to_dyn_abi(cx) }
    }
}

impl ToAbi for ast::ItemEvent {
    type DynAbi = Event;

    fn to_dyn_abi(&self, cx: &ExpCtxt<'_>) -> Self::DynAbi {
        Event {
            name: self.name.as_string(),
            inputs: self.parameters.iter().map(|e| e.to_dyn_abi(cx)).collect(),
            anonymous: self.is_anonymous(),
        }
    }
}

impl<P> ToAbi for ast::Parameters<P> {
    type DynAbi = Vec<Param>;

    fn to_dyn_abi(&self, cx: &ExpCtxt<'_>) -> Self::DynAbi {
        self.iter().map(|p| p.to_dyn_abi(cx)).collect()
    }
}

impl ToAbi for ast::VariableDeclaration {
    type DynAbi = Param;

    fn to_dyn_abi(&self, cx: &ExpCtxt<'_>) -> Self::DynAbi {
        ty_to_param(self.name.as_ref().map(ast::SolIdent::as_string), &self.ty, cx)
    }
}

impl ToAbi for ast::EventParameter {
    type DynAbi = EventParam;

    fn to_dyn_abi(&self, cx: &ExpCtxt<'_>) -> Self::DynAbi {
        let name = self.name.as_ref().map(ast::SolIdent::as_string);
        let Param { ty, name, components, internal_type } = ty_to_param(name, &self.ty, cx);
        EventParam { ty, name, indexed: self.is_indexed(), internal_type, components }
    }
}

impl ToAbi for ast::FunctionAttributes {
    type DynAbi = StateMutability;

    fn to_dyn_abi(&self, _cx: &ExpCtxt<'_>) -> Self::DynAbi {
        match self.mutability() {
            Some(ast::Mutability::Pure(_) | ast::Mutability::Constant(_)) => StateMutability::Pure,
            Some(ast::Mutability::View(_)) => StateMutability::View,
            Some(ast::Mutability::Payable(_)) => StateMutability::Payable,
            None => StateMutability::NonPayable,
        }
    }
}

fn ty_to_param(name: Option<String>, ty: &ast::Type, cx: &ExpCtxt<'_>) -> Param {
    let mut ty_name = ty_abi_string(ty, cx);

    // HACK: `cx.custom_type` resolves the custom type recursively, so in recursive structs the
    // peeled `ty` will be `Tuple` rather than `Custom`.
    if ty_name.starts_with('(') {
        let paren_i = ty_name.rfind(')').expect("malformed tuple type");
        let suffix = &ty_name[paren_i + 1..];
        ty_name = format!("tuple{suffix}");
    }

    let mut component_names = vec![];
    let resolved = match ty.peel_arrays() {
        ast::Type::Custom(name) => {
            if let ast::Item::Struct(s) = cx.item(name) {
                component_names = s
                    .fields
                    .names()
                    .map(|n| n.map(|i| i.as_string()).unwrap_or_default())
                    .collect();
            }
            cx.custom_type(name)
        }
        ty => ty,
    };

    let components = if let ast::Type::Tuple(tuple) = resolved {
        tuple
            .types
            .iter()
            .enumerate()
            .map(|(i, ty)| ty_to_param(component_names.get(i).cloned(), ty, cx))
            .collect()
    } else {
        vec![]
    };

    // TODO: internal_type
    let internal_type = None;

    Param { ty: ty_name, name: name.unwrap_or_default(), internal_type, components }
}

fn ty_abi_string(ty: &ast::Type, cx: &ExpCtxt<'_>) -> String {
    let mut suffix = String::new();
    rec_ty_abi_string_suffix(ty, &mut suffix);

    let mut ty = ty.peel_arrays();
    if let ast::Type::Custom(name) = ty {
        match cx.try_custom_type(name) {
            Some(ast::Type::Tuple(_)) => return format!("tuple{suffix}"),
            Some(custom) => ty = custom,
            None => {}
        }
    }
    format!("{}{suffix}", super::ty::TypePrinter::new(cx, ty))
}

fn rec_ty_abi_string_suffix(ty: &ast::Type, s: &mut String) {
    if let ast::Type::Array(array) = ty {
        rec_ty_abi_string_suffix(&array.ty, s);
        if let Some(size) = array.size() {
            write!(s, "[{size}]").unwrap();
        } else {
            s.push_str("[]");
        }
    }
}

pub(super) fn constructor(function: &ItemFunction, cx: &ExpCtxt<'_>) -> Constructor {
    assert!(function.kind.is_constructor());
    Constructor {
        inputs: function.parameters.to_dyn_abi(cx),
        state_mutability: function.attributes.to_dyn_abi(cx),
    }
}

pub(super) fn fallback(function: &ItemFunction, _cx: &ExpCtxt<'_>) -> Fallback {
    assert!(function.kind.is_fallback());
    Fallback { state_mutability: StateMutability::NonPayable }
}

pub(super) fn receive(function: &ItemFunction, _cx: &ExpCtxt<'_>) -> Receive {
    assert!(function.kind.is_receive());
    Receive { state_mutability: StateMutability::Payable }
}

macro_rules! make_map {
    ($items:ident, $cx:ident) => {{
        let mut map = std::collections::BTreeMap::<String, Vec<_>>::new();
        for item in $items {
            let item = item.to_dyn_abi($cx);
            map.entry(item.name.clone()).or_default().push(item);
        }
        crate::verbatim::verbatim(&map, &$cx.crates)
    }};
}

pub(super) fn functions_map(functions: &[ItemFunction], cx: &ExpCtxt<'_>) -> TokenStream {
    make_map!(functions, cx)
}

pub(super) fn events_map(events: &[&ItemEvent], cx: &ExpCtxt<'_>) -> TokenStream {
    make_map!(events, cx)
}

pub(super) fn errors_map(errors: &[&ItemError], cx: &ExpCtxt<'_>) -> TokenStream {
    make_map!(errors, cx)
}