use crate::{
    Enum, Flags, Ident, Interface, InterfaceItem, Package, PackageName, Params, Record, Resource,
    ResourceFunc, Result_, StandaloneFunc, Tuple, Type, TypeDef, TypeDefKind, Variant, World,
    WorldItem,
};
use id_arena::Id;
use wit_parser::PackageId;

pub fn packages_from_parsed(resolve: &wit_parser::Resolve) -> Vec<Package> {
    let converter = Converter::new(resolve);
    converter.convert()
}

struct Converter<'a> {
    resolve: &'a wit_parser::Resolve,
}

impl<'a> Converter<'a> {
    fn new(resolve: &'a wit_parser::Resolve) -> Self {
        Self { resolve }
    }

    fn convert(&self) -> Vec<Package> {
        self.resolve
            .packages
            .iter()
            .map(|(p_id, p)| self.convert_package(p_id, p))
            .collect()
    }

    fn convert_package(&self, package_id: PackageId, package: &wit_parser::Package) -> Package {
        let mut output = Package::new(self.convert_package_name(&package.name));
        for (_, id) in &package.interfaces {
            let interface = self.resolve.interfaces.get(*id).unwrap();
            output.interface(self.convert_interface(
                package_id,
                interface,
                None,
                wit_parser::TypeOwner::Interface(*id),
            ));
        }
        for (_, id) in &package.worlds {
            let world = self.resolve.worlds.get(*id).unwrap();
            output.world(self.convert_world(package_id, world, wit_parser::TypeOwner::World(*id)));
        }
        output
    }

    fn convert_package_name(&self, package: &wit_parser::PackageName) -> PackageName {
        PackageName::new(
            package.namespace.clone(),
            package.name.clone(),
            package.version.clone(),
        )
    }

    fn convert_world(
        &self,
        package_id: PackageId,
        world: &wit_parser::World,
        owner: wit_parser::TypeOwner,
    ) -> World {
        let mut output = World::new(world.name.clone());

        for (key, item) in &world.imports {
            match item {
                wit_parser::WorldItem::Interface { id, .. } => {
                    let interface = self.resolve.interfaces.get(*id).unwrap();
                    let ident = self.interface_ident(package_id, Some(key), interface);

                    if interface.name.is_some() {
                        output.item(WorldItem::named_interface_import(ident))
                    } else {
                        output.item(WorldItem::inline_interface_import(self.convert_interface(
                            package_id,
                            interface,
                            Some(ident),
                            owner,
                        )))
                    }
                }
                wit_parser::WorldItem::Function(func) => {
                    if let Some(func) = self.standalone_func_convert(func) {
                        output.item(WorldItem::function_import(func));
                    }
                }
                wit_parser::WorldItem::Type(type_id) => {
                    let (target, item, rename) = self.convert_world_item_type(package_id, *type_id);
                    output.use_type(target, item, rename)
                }
            }
        }

        for (key, item) in &world.exports {
            match item {
                wit_parser::WorldItem::Interface { id, .. } => {
                    let interface = self.resolve.interfaces.get(*id).unwrap();
                    let ident = self.interface_ident(package_id, Some(key), interface);
                    if interface.name.is_some() {
                        output.item(WorldItem::named_interface_export(ident));
                    } else {
                        output.item(WorldItem::inline_interface_export(self.convert_interface(
                            package_id,
                            interface,
                            Some(ident),
                            owner,
                        )));
                    }
                }
                wit_parser::WorldItem::Function(func) => {
                    if let Some(func) = self.standalone_func_convert(func) {
                        output.item(WorldItem::function_export(func));
                    }
                }
                wit_parser::WorldItem::Type(type_id) => {
                    let (target, item, rename) = self.convert_world_item_type(package_id, *type_id);
                    output.use_type(target, item, rename)
                }
            }
        }

        output.uses_mut().sort();
        output.items_mut().sort();

        output
    }

    fn convert_world_item_type(
        &self,
        package_id: PackageId,
        type_id: wit_parser::TypeId,
    ) -> (Ident, Ident, Option<Ident>) {
        let type_def = self.resolve.types.get(type_id).unwrap();
        let underlying_type_def = self.underlying_type_def(&type_def);
        let interface_ident = self
            .type_def_owner_interface_ident(package_id, underlying_type_def)
            .expect("Type not part of an interface");
        let local_type_name = type_def.name.clone().unwrap();
        let underlying_local_type_name = underlying_type_def.name.clone().unwrap();
        if underlying_local_type_name == local_type_name {
            (interface_ident, local_type_name.into(), None)
        } else {
            (
                interface_ident,
                underlying_local_type_name.into(),
                Some(local_type_name.into()),
            )
        }
    }

    fn convert_interface(
        &self,
        package_id: PackageId,
        interface: &wit_parser::Interface,
        inlined_name: Option<Ident>,
        owner: wit_parser::TypeOwner,
    ) -> Interface {
        let mut output =
            Interface::new(interface.name.clone().map(Ident::new).unwrap_or_else(|| {
                inlined_name
                    .clone()
                    .expect("inlined interface must pass in inlined_name")
            }));

        for (_, func) in &interface.functions {
            if let Some(func) = self.standalone_func_convert(func) {
                output.items.push(InterfaceItem::Function(func));
            }
        }
        for (_, type_id) in &interface.types {
            let type_def = self.resolve.types.get(*type_id).unwrap();
            let underlying_type_def = self.underlying_type_def(&type_def);

            if underlying_type_def.owner == owner {
                if let Some(type_def) = self.convert_type_def(type_def, *type_id) {
                    output.item(InterfaceItem::TypeDef(type_def));
                }
            } else {
                let interface_ident = self
                    .type_def_owner_interface_ident(package_id, underlying_type_def)
                    .expect("Type not part of an interface");
                let local_type_name = type_def.name.clone().unwrap();
                let underlying_local_type_name = underlying_type_def.name.clone().unwrap();
                if underlying_local_type_name == local_type_name {
                    output.use_type(interface_ident, local_type_name, None);
                } else {
                    output.use_type(
                        interface_ident,
                        underlying_local_type_name,
                        Some(local_type_name.into()),
                    );
                }
            }
        }

        output.uses_mut().sort();
        output.items_mut().sort();

        output
    }

    fn convert_type_def(
        &self,
        type_def: &wit_parser::TypeDef,
        type_def_id: Id<wit_parser::TypeDef>,
    ) -> Option<TypeDef> {
        match &type_def.name {
            None => None,
            Some(name) => {
                let kind = match &type_def.kind {
                    wit_parser::TypeDefKind::Record(record) => {
                        let output = self.convert_record(record);
                        TypeDefKind::Record(output)
                    }
                    wit_parser::TypeDefKind::Resource => {
                        let output = self.convert_resource(type_def_id, name, &type_def.owner);
                        TypeDefKind::Resource(output)
                    }
                    wit_parser::TypeDefKind::Flags(flags) => {
                        let output = self.convert_flags(flags);
                        TypeDefKind::Flags(output)
                    }
                    wit_parser::TypeDefKind::Variant(variant) => {
                        let output = self.convert_variant(variant);
                        TypeDefKind::Variant(output)
                    }
                    wit_parser::TypeDefKind::Enum(enum_) => {
                        let output = self.convert_enum(enum_);
                        TypeDefKind::Enum(output)
                    }
                    wit_parser::TypeDefKind::Future(ty) => {
                        TypeDefKind::Type(Type::future(self.convert_option_type(ty)))
                    }
                    wit_parser::TypeDefKind::Stream(ty) => {
                        TypeDefKind::Type(Type::stream(self.convert_option_type(ty)))
                    }
                    // all the following are just `type` declarations
                    wit_parser::TypeDefKind::Option(ty) => {
                        let output = Type::option(self.convert_type(ty));
                        TypeDefKind::Type(output)
                    }
                    wit_parser::TypeDefKind::List(ty) => {
                        let output = Type::list(self.convert_type(ty));
                        TypeDefKind::Type(output)
                    }
                    wit_parser::TypeDefKind::FixedSizeList(ty, size) => {
                        let output = Type::fixed_size_list(self.convert_type(ty), *size);
                        TypeDefKind::Type(output)
                    }
                    wit_parser::TypeDefKind::Handle(handle) => {
                        let output = self.handle_to_type(handle);
                        TypeDefKind::Type(output)
                    }
                    wit_parser::TypeDefKind::Result(result) => {
                        let output = Type::result(self.convert_result(result));
                        TypeDefKind::Type(output)
                    }
                    wit_parser::TypeDefKind::Tuple(tuple) => {
                        let output = Type::Tuple(self.convert_tuple(tuple));
                        TypeDefKind::Type(output)
                    }
                    wit_parser::TypeDefKind::Type(ty) => {
                        let output = self.convert_type(ty);
                        TypeDefKind::Type(output)
                    }
                    wit_parser::TypeDefKind::Unknown => unreachable!(),
                };

                Some(TypeDef::new(name.clone(), kind))
            }
        }
    }

    fn convert_option_type(&self, ty: &Option<wit_parser::Type>) -> Option<Type> {
        ty.as_ref().map(|ty| self.convert_type(ty))
    }

    fn convert_type(&self, type_: &wit_parser::Type) -> Type {
        match type_ {
            wit_parser::Type::Bool => Type::Bool,
            wit_parser::Type::U8 => Type::U8,
            wit_parser::Type::U16 => Type::U16,
            wit_parser::Type::U32 => Type::U32,
            wit_parser::Type::U64 => Type::U64,
            wit_parser::Type::S8 => Type::S8,
            wit_parser::Type::S16 => Type::S16,
            wit_parser::Type::S32 => Type::S32,
            wit_parser::Type::S64 => Type::S64,
            wit_parser::Type::F32 => Type::F32,
            wit_parser::Type::F64 => Type::F64,
            wit_parser::Type::Char => Type::Char,
            wit_parser::Type::String => Type::String,
            wit_parser::Type::ErrorContext => Type::ErrorContext,
            wit_parser::Type::Id(id) => {
                let type_def = self.resolve.types.get(*id).expect("Type not found");
                match &type_def.name {
                    Some(name) => Type::named(name.clone()),
                    None => match &type_def.kind {
                        wit_parser::TypeDefKind::Tuple(tuple) => {
                            Type::Tuple(self.convert_tuple(tuple))
                        }
                        wit_parser::TypeDefKind::Option(type_) => {
                            Type::option(self.convert_type(type_))
                        }
                        wit_parser::TypeDefKind::Result(result) => {
                            Type::result(self.convert_result(result))
                        }
                        wit_parser::TypeDefKind::List(type_) => {
                            Type::list(self.convert_type(type_))
                        }
                        wit_parser::TypeDefKind::FixedSizeList(type_, size) => {
                            Type::fixed_size_list(self.convert_type(type_), *size)
                        }
                        wit_parser::TypeDefKind::Handle(handle) => self.handle_to_type(handle),
                        wit_parser::TypeDefKind::Future(type_) => {
                            Type::future(self.convert_option_type(type_))
                        }
                        wit_parser::TypeDefKind::Stream(type_) => {
                            Type::stream(self.convert_option_type(type_))
                        }
                        wit_parser::TypeDefKind::Record(_)
                        | wit_parser::TypeDefKind::Resource
                        | wit_parser::TypeDefKind::Flags(_)
                        | wit_parser::TypeDefKind::Variant(_)
                        | wit_parser::TypeDefKind::Enum(_)
                        | wit_parser::TypeDefKind::Type(_) => {
                            panic!("type doesn't have a name, and can't be inlined")
                        }
                        wit_parser::TypeDefKind::Unknown => unreachable!(),
                    },
                }
            }
        }
    }

    fn convert_enum(&self, enum_: &wit_parser::Enum) -> Enum {
        let mut output = Enum::empty();
        for case in &enum_.cases {
            output.case(case.name.clone())
        }
        output
    }
    fn convert_record(&self, record: &wit_parser::Record) -> Record {
        Record::new(record.fields.iter().map(|field| {
            let name = field.name.clone();
            let type_ = self.convert_type(&field.ty);
            (name, type_)
        }))
    }
    fn convert_variant(&self, variant: &wit_parser::Variant) -> Variant {
        let mut output = Variant::empty();
        for case in &variant.cases {
            match &case.ty {
                Some(ty) => {
                    let ty = self.convert_type(ty);
                    output.case((case.name.clone(), ty))
                }
                None => output.case((case.name.clone(),)),
            }
        }
        output
    }
    fn convert_flags(&self, flags: &wit_parser::Flags) -> Flags {
        Flags::new(flags.flags.iter().map(|flag| (flag.name.clone(),)))
    }

    fn convert_resource(
        &self,
        resource_id: Id<wit_parser::TypeDef>,
        name: &str,
        owner: &wit_parser::TypeOwner,
    ) -> Resource {
        let functions = match owner {
            wit_parser::TypeOwner::World(_) => {
                todo!("Enable once win-encoder supports `include`")
            }
            wit_parser::TypeOwner::Interface(id) => {
                &self.resolve.interfaces.get(*id).unwrap().functions
            }
            wit_parser::TypeOwner::None => panic!("Resource has to have an owner"),
        };

        let mut output = Resource::empty();
        for (_, func) in functions {
            if let Some(method) = self.convert_resource_func(resource_id, name, func) {
                output.func(method);
            }
        }
        output
    }

    fn convert_resource_func(
        &self,
        resource_id: Id<wit_parser::TypeDef>,
        resource_name: &str,
        func: &wit_parser::Function,
    ) -> Option<ResourceFunc> {
        // skip first argument for methods, as they're just `self`.
        let mut skip_first_param = false;
        let mut with_returns = true;
        let mut method = match func.kind {
            wit_parser::FunctionKind::Freestanding
            | wit_parser::FunctionKind::AsyncFreestanding => return None,
            wit_parser::FunctionKind::Method(id) | wit_parser::FunctionKind::AsyncMethod(id) => {
                if id != resource_id {
                    return None;
                }
                skip_first_param = true;
                let name = clean_func_name(resource_name, &func.name);
                let async_ = matches!(func.kind, wit_parser::FunctionKind::AsyncMethod(_));
                ResourceFunc::method(name, async_)
            }
            wit_parser::FunctionKind::Static(id) | wit_parser::FunctionKind::AsyncStatic(id) => {
                if id != resource_id {
                    return None;
                }
                let name = clean_func_name(resource_name, &func.name);
                let async_ = matches!(func.kind, wit_parser::FunctionKind::AsyncStatic(_));
                ResourceFunc::static_(name, async_)
            }
            wit_parser::FunctionKind::Constructor(id) => {
                if id != resource_id {
                    return None;
                }
                with_returns = !func.is_constructor_shorthand(self.resolve);
                ResourceFunc::constructor()
            }
        };

        method.set_params(self.convert_params(&func.params));
        if skip_first_param {
            method.params_mut().items_mut().remove(0);
        }

        if with_returns {
            method.set_result(func.result.as_ref().map(|ty| self.convert_type(ty)));
        }

        Some(method)
    }

    fn standalone_func_convert(&self, func: &wit_parser::Function) -> Option<StandaloneFunc> {
        match func.kind {
            wit_parser::FunctionKind::Method(_)
            | wit_parser::FunctionKind::AsyncMethod(_)
            | wit_parser::FunctionKind::Static(_)
            | wit_parser::FunctionKind::AsyncStatic(_)
            | wit_parser::FunctionKind::Constructor(_) => None,
            wit_parser::FunctionKind::Freestanding
            | wit_parser::FunctionKind::AsyncFreestanding => {
                let async_ = matches!(func.kind, wit_parser::FunctionKind::AsyncFreestanding);
                let mut output = StandaloneFunc::new(func.name.clone(), async_);

                output.set_params(self.convert_params(&func.params));
                output.set_result(func.result.map(|ty| self.convert_type(&ty)));

                Some(output)
            }
        }
    }

    fn convert_params(&self, params: &[(String, wit_parser::Type)]) -> Params {
        let mut output = Params::empty();
        for (name, ty) in params.iter() {
            let name = name.to_string();
            let ty = self.convert_type(ty);
            output.push(name, ty);
        }
        output
    }

    fn handle_to_type(&self, handle: &wit_parser::Handle) -> Type {
        let id = match handle {
            wit_parser::Handle::Own(id) => id,
            wit_parser::Handle::Borrow(id) => id,
        };
        let type_def = self.resolve.types.get(*id).expect("Type not found");
        let name = type_def
            .name
            .clone()
            .expect("Handles should only be for resources, and resources should have names");
        match handle {
            wit_parser::Handle::Own(_) => Type::named(name),
            wit_parser::Handle::Borrow(_) => Type::borrow(name),
        }
    }

    fn convert_result(&self, result: &wit_parser::Result_) -> Result_ {
        match (&result.ok, &result.err) {
            (None, None) => Result_::empty(),
            (Some(ok), None) => Result_::ok(self.convert_type(ok)),
            (None, Some(err)) => Result_::err(self.convert_type(err)),
            (Some(ok), Some(err)) => Result_::both(self.convert_type(ok), self.convert_type(err)),
        }
    }

    fn convert_tuple(&self, tuple: &wit_parser::Tuple) -> Tuple {
        let mut output = Tuple::empty();
        for ty in tuple.types.iter() {
            output.types_mut().push(self.convert_type(ty));
        }
        output
    }

    fn interface_ident(
        &self,
        package_id: PackageId,
        world_key: Option<&wit_parser::WorldKey>,
        interface: &wit_parser::Interface,
    ) -> Ident {
        match &interface.name {
            Some(name) => {
                // Standalone
                if interface.package == Some(package_id) {
                    Ident::new(name.clone())
                } else {
                    let package = interface
                        .package
                        .map(|package_id| self.resolve.packages.get(package_id).unwrap());

                    match package {
                        Some(package) => Ident::new(format!(
                            "{}:{}/{}{}",
                            package.name.namespace,
                            package.name.name,
                            name,
                            package
                                .name
                                .version
                                .as_ref()
                                .map(|version| format!("@{version}"))
                                .unwrap_or_else(|| "".to_string())
                        )),
                        None => Ident::new(name.clone()),
                    }
                }
            }
            None => match world_key {
                Some(world_key) => match world_key {
                    wit_parser::WorldKey::Name(name) => Ident::new(name.clone()),
                    wit_parser::WorldKey::Interface(_) => {
                        unreachable!("inlined interface must have a world key name")
                    }
                },
                None => panic!("inlined interface requires a world key"),
            },
        }
    }

    fn underlying_type_def(&'a self, type_def: &'a wit_parser::TypeDef) -> &'a wit_parser::TypeDef {
        match &type_def.kind {
            wit_parser::TypeDefKind::Type(type_) => match &type_ {
                wit_parser::Type::Id(type_id) => {
                    let type_def = self.resolve.types.get(*type_id).unwrap();
                    type_def
                }
                _ => type_def,
            },
            _ => type_def,
        }
    }

    fn type_def_owner_interface_ident(
        &self,
        package_id: PackageId,
        type_def: &wit_parser::TypeDef,
    ) -> Option<Ident> {
        if let wit_parser::TypeOwner::Interface(id) = type_def.owner {
            Some(self.interface_ident(package_id, None, self.resolve.interfaces.get(id).unwrap()))
        } else {
            None
        }
    }
}

fn clean_func_name(resource_name: &str, method_name: &str) -> String {
    const METHOD_PREFIX: &str = "[method]";
    const STATIC_PREFIX: &str = "[static]";

    let method_name = method_name
        .strip_prefix(METHOD_PREFIX)
        .unwrap_or(method_name);
    let method_name = method_name
        .strip_prefix(STATIC_PREFIX)
        .unwrap_or(method_name);
    let method_name = method_name.strip_prefix(resource_name).unwrap();
    let method_name = method_name.strip_prefix(".").unwrap();
    method_name.to_string()
}
