/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use std::io::Write;

use crate::bindgen::config::{Config, Language};
use crate::bindgen::declarationtyperesolver::DeclarationTypeResolver;
use crate::bindgen::dependencies::Dependencies;
use crate::bindgen::ir::{
    AnnotationSet, Cfg, ConditionWrite, Documentation, GenericArgument, GenericParams, Item,
    ItemContainer, Path, ToCondition,
};
use crate::bindgen::library::Library;
use crate::bindgen::mangle;
use crate::bindgen::monomorph::Monomorphs;
use crate::bindgen::writer::{Source, SourceWriter};

#[derive(Debug, Clone)]
pub struct OpaqueItem {
    pub path: Path,
    pub export_name: String,
    pub generic_params: GenericParams,
    pub cfg: Option<Cfg>,
    pub annotations: AnnotationSet,
    pub documentation: Documentation,
}

impl OpaqueItem {
    pub fn load(
        path: Path,
        generics: &syn::Generics,
        attrs: &[syn::Attribute],
        mod_cfg: Option<&Cfg>,
    ) -> Result<OpaqueItem, String> {
        Ok(Self::new(
            path,
            GenericParams::load(generics)?,
            Cfg::append(mod_cfg, Cfg::load(attrs)),
            AnnotationSet::load(attrs).unwrap_or_else(|_| AnnotationSet::new()),
            Documentation::load(attrs),
        ))
    }

    pub fn new(
        path: Path,
        generic_params: GenericParams,
        cfg: Option<Cfg>,
        annotations: AnnotationSet,
        documentation: Documentation,
    ) -> OpaqueItem {
        let export_name = path.name().to_owned();
        Self {
            path,
            export_name,
            generic_params,
            cfg,
            annotations,
            documentation,
        }
    }
}

impl Item for OpaqueItem {
    fn path(&self) -> &Path {
        &self.path
    }

    fn export_name(&self) -> &str {
        &self.export_name
    }

    fn cfg(&self) -> Option<&Cfg> {
        self.cfg.as_ref()
    }

    fn annotations(&self) -> &AnnotationSet {
        &self.annotations
    }

    fn annotations_mut(&mut self) -> &mut AnnotationSet {
        &mut self.annotations
    }

    fn container(&self) -> ItemContainer {
        ItemContainer::OpaqueItem(self.clone())
    }

    fn collect_declaration_types(&self, resolver: &mut DeclarationTypeResolver) {
        resolver.add_struct(&self.path);
    }

    fn rename_for_config(&mut self, config: &Config) {
        config.export.rename(&mut self.export_name);
    }

    fn add_dependencies(&self, _: &Library, _: &mut Dependencies) {}

    fn instantiate_monomorph(
        &self,
        generic_values: &[GenericArgument],
        library: &Library,
        out: &mut Monomorphs,
    ) {
        assert!(
            !self.generic_params.is_empty(),
            "{} is not generic",
            self.path
        );

        // We can be instantiated with less generic params because of default
        // template parameters, or because of empty types that we remove during
        // parsing (`()`).
        assert!(
            self.generic_params.len() >= generic_values.len(),
            "{} has {} params but is being instantiated with {} values",
            self.path,
            self.generic_params.len(),
            generic_values.len(),
        );

        let mangled_path = mangle::mangle_path(
            &self.path,
            generic_values,
            &library.get_config().export.mangle,
        );

        let monomorph = OpaqueItem::new(
            mangled_path,
            GenericParams::default(),
            self.cfg.clone(),
            self.annotations.clone(),
            self.documentation.clone(),
        );

        out.insert_opaque(self, monomorph, generic_values.to_owned());
    }
}

impl Source for OpaqueItem {
    fn write<F: Write>(&self, config: &Config, out: &mut SourceWriter<F>) {
        let condition = self.cfg.to_condition(config);
        condition.write_before(config, out);

        self.documentation.write(config, out);

        self.generic_params.write_with_default(config, out);

        match config.language {
            Language::C if config.style.generate_typedef() => {
                write!(
                    out,
                    "typedef struct {} {};",
                    self.export_name(),
                    self.export_name()
                );
            }
            Language::C | Language::Cxx => {
                write!(out, "struct {};", self.export_name());
            }
            Language::Cython => {
                write!(
                    out,
                    "{}struct {}",
                    config.style.cython_def(),
                    self.export_name()
                );
                out.open_brace();
                out.write("pass");
                out.close_brace(false);
            }
        }

        condition.write_after(config, out);
    }
}
