/*
 * TODO(antoyo): support #[inline] attributes.
 * TODO(antoyo): support LTO.
 *
 * TODO(antoyo): remove the patches.
 */

#![feature(rustc_private, decl_macro, associated_type_bounds, never_type, trusted_len)]
#![allow(broken_intra_doc_links)]
#![recursion_limit="256"]
#![warn(rust_2018_idioms)]
#![warn(unused_lifetimes)]

extern crate rustc_ast;
extern crate rustc_codegen_ssa;
extern crate rustc_data_structures;
extern crate rustc_errors;
extern crate rustc_hir;
extern crate rustc_metadata;
extern crate rustc_middle;
extern crate rustc_session;
extern crate rustc_span;
extern crate rustc_target;

// This prevents duplicating functions and statics that are already part of the host rustc process.
#[allow(unused_extern_crates)]
extern crate rustc_driver;

mod abi;
mod allocator;
mod archive;
mod asm;
mod back;
mod base;
mod builder;
mod callee;
mod common;
mod consts;
mod context;
mod coverageinfo;
mod debuginfo;
mod declare;
mod intrinsic;
mod mono_item;
mod type_;
mod type_of;

use std::any::Any;
use std::sync::Arc;

use gccjit::{Context, OptimizationLevel};
use rustc_ast::expand::allocator::AllocatorKind;
use rustc_codegen_ssa::{CodegenResults, CompiledModule, ModuleCodegen};
use rustc_codegen_ssa::base::codegen_crate;
use rustc_codegen_ssa::back::write::{CodegenContext, FatLTOInput, ModuleConfig, TargetMachineFactoryFn};
use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};
use rustc_codegen_ssa::target_features::supported_target_features;
use rustc_codegen_ssa::traits::{CodegenBackend, ExtraBackendMethods, ModuleBufferMethods, ThinBufferMethods, WriteBackendMethods};
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::{ErrorReported, Handler};
use rustc_metadata::EncodedMetadata;
use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
use rustc_middle::ty::TyCtxt;
use rustc_session::config::{Lto, OptLevel, OutputFilenames};
use rustc_session::Session;
use rustc_span::Symbol;
use rustc_span::fatal_error::FatalError;

pub struct PrintOnPanic<F: Fn() -> String>(pub F);

impl<F: Fn() -> String> Drop for PrintOnPanic<F> {
    fn drop(&mut self) {
        if ::std::thread::panicking() {
            println!("{}", (self.0)());
        }
    }
}

#[derive(Clone)]
pub struct GccCodegenBackend;

impl CodegenBackend for GccCodegenBackend {
    fn init(&self, sess: &Session) {
        if sess.lto() != Lto::No {
            sess.warn("LTO is not supported. You may get a linker error.");
        }
    }

    fn codegen_crate<'tcx>(&self, tcx: TyCtxt<'tcx>, metadata: EncodedMetadata, need_metadata_module: bool) -> Box<dyn Any> {
        let target_cpu = target_cpu(tcx.sess);
        let res = codegen_crate(self.clone(), tcx, target_cpu.to_string(), metadata, need_metadata_module);

        Box::new(res)
    }

    fn join_codegen(&self, ongoing_codegen: Box<dyn Any>, sess: &Session, _outputs: &OutputFilenames) -> Result<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>), ErrorReported> {
        let (codegen_results, work_products) = ongoing_codegen
            .downcast::<rustc_codegen_ssa::back::write::OngoingCodegen<GccCodegenBackend>>()
            .expect("Expected GccCodegenBackend's OngoingCodegen, found Box<Any>")
            .join(sess);

        Ok((codegen_results, work_products))
    }

    fn link(&self, sess: &Session, codegen_results: CodegenResults, outputs: &OutputFilenames) -> Result<(), ErrorReported> {
        use rustc_codegen_ssa::back::link::link_binary;

        link_binary::<crate::archive::ArArchiveBuilder<'_>>(
            sess,
            &codegen_results,
            outputs,
        )
    }

    fn target_features(&self, sess: &Session) -> Vec<Symbol> {
        target_features(sess)
    }
}

impl ExtraBackendMethods for GccCodegenBackend {
    fn new_metadata<'tcx>(&self, _tcx: TyCtxt<'tcx>, _mod_name: &str) -> Self::Module {
        GccContext {
            context: Context::default(),
        }
    }

    fn codegen_allocator<'tcx>(&self, tcx: TyCtxt<'tcx>, mods: &mut Self::Module, module_name: &str, kind: AllocatorKind, has_alloc_error_handler: bool) {
        unsafe { allocator::codegen(tcx, mods, module_name, kind, has_alloc_error_handler) }
    }

    fn compile_codegen_unit<'tcx>(&self, tcx: TyCtxt<'tcx>, cgu_name: Symbol) -> (ModuleCodegen<Self::Module>, u64) {
        base::compile_codegen_unit(tcx, cgu_name)
    }

    fn target_machine_factory(&self, _sess: &Session, _opt_level: OptLevel) -> TargetMachineFactoryFn<Self> {
        // TODO(antoyo): set opt level.
        Arc::new(|_| {
            Ok(())
        })
    }

    fn target_cpu<'b>(&self, _sess: &'b Session) -> &'b str {
        unimplemented!();
    }

    fn tune_cpu<'b>(&self, _sess: &'b Session) -> Option<&'b str> {
        None
        // TODO(antoyo)
    }
}

pub struct ModuleBuffer;

impl ModuleBufferMethods for ModuleBuffer {
    fn data(&self) -> &[u8] {
        unimplemented!();
    }
}

pub struct ThinBuffer;

impl ThinBufferMethods for ThinBuffer {
    fn data(&self) -> &[u8] {
        unimplemented!();
    }
}

pub struct GccContext {
    context: Context<'static>,
}

unsafe impl Send for GccContext {}
// FIXME(antoyo): that shouldn't be Sync. Parallel compilation is currently disabled with "-Zno-parallel-llvm". Try to disable it here.
unsafe impl Sync for GccContext {}

impl WriteBackendMethods for GccCodegenBackend {
    type Module = GccContext;
    type TargetMachine = ();
    type ModuleBuffer = ModuleBuffer;
    type Context = ();
    type ThinData = ();
    type ThinBuffer = ThinBuffer;

    fn run_fat_lto(_cgcx: &CodegenContext<Self>, mut modules: Vec<FatLTOInput<Self>>, _cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>) -> Result<LtoModuleCodegen<Self>, FatalError> {
        // TODO(antoyo): implement LTO by sending -flto to libgccjit and adding the appropriate gcc linker plugins.
        // NOTE: implemented elsewhere.
        // TODO: what is implemented elsewhere ^ ?
        let module =
            match modules.remove(0) {
                FatLTOInput::InMemory(module) => module,
                FatLTOInput::Serialized { .. } => {
                    unimplemented!();
                }
            };
        Ok(LtoModuleCodegen::Fat { module: Some(module), _serialized_bitcode: vec![] })
    }

    fn run_thin_lto(_cgcx: &CodegenContext<Self>, _modules: Vec<(String, Self::ThinBuffer)>, _cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>) -> Result<(Vec<LtoModuleCodegen<Self>>, Vec<WorkProduct>), FatalError> {
        unimplemented!();
    }

    fn print_pass_timings(&self) {
        unimplemented!();
    }

    unsafe fn optimize(_cgcx: &CodegenContext<Self>, _diag_handler: &Handler, module: &ModuleCodegen<Self::Module>, config: &ModuleConfig) -> Result<(), FatalError> {
        module.module_llvm.context.set_optimization_level(to_gcc_opt_level(config.opt_level));
        Ok(())
    }

    unsafe fn optimize_thin(_cgcx: &CodegenContext<Self>, _thin: &mut ThinModule<Self>) -> Result<ModuleCodegen<Self::Module>, FatalError> {
        unimplemented!();
    }

    unsafe fn codegen(cgcx: &CodegenContext<Self>, diag_handler: &Handler, module: ModuleCodegen<Self::Module>, config: &ModuleConfig) -> Result<CompiledModule, FatalError> {
        back::write::codegen(cgcx, diag_handler, module, config)
    }

    fn prepare_thin(_module: ModuleCodegen<Self::Module>) -> (String, Self::ThinBuffer) {
        unimplemented!();
    }

    fn serialize_module(_module: ModuleCodegen<Self::Module>) -> (String, Self::ModuleBuffer) {
        unimplemented!();
    }

    fn run_lto_pass_manager(_cgcx: &CodegenContext<Self>, _module: &ModuleCodegen<Self::Module>, _config: &ModuleConfig, _thin: bool) -> Result<(), FatalError> {
        // TODO(antoyo)
        Ok(())
    }

    fn run_link(cgcx: &CodegenContext<Self>, diag_handler: &Handler, modules: Vec<ModuleCodegen<Self::Module>>) -> Result<ModuleCodegen<Self::Module>, FatalError> {
        back::write::link(cgcx, diag_handler, modules)
    }
}

/// This is the entrypoint for a hot plugged rustc_codegen_gccjit
#[no_mangle]
pub fn __rustc_codegen_backend() -> Box<dyn CodegenBackend> {
    Box::new(GccCodegenBackend)
}

fn to_gcc_opt_level(optlevel: Option<OptLevel>) -> OptimizationLevel {
    match optlevel {
        None => OptimizationLevel::None,
        Some(level) => {
            match level {
                OptLevel::No => OptimizationLevel::None,
                OptLevel::Less => OptimizationLevel::Limited,
                OptLevel::Default => OptimizationLevel::Standard,
                OptLevel::Aggressive => OptimizationLevel::Aggressive,
                OptLevel::Size | OptLevel::SizeMin => OptimizationLevel::Limited,
            }
        },
    }
}

fn handle_native(name: &str) -> &str {
    if name != "native" {
        return name;
    }

    unimplemented!();
}

pub fn target_cpu(sess: &Session) -> &str {
    let name = sess.opts.cg.target_cpu.as_ref().unwrap_or(&sess.target.cpu);
    handle_native(name)
}

pub fn target_features(sess: &Session) -> Vec<Symbol> {
    supported_target_features(sess)
        .iter()
        .filter_map(
            |&(feature, gate)| {
                if sess.is_nightly_build() || gate.is_none() { Some(feature) } else { None }
            },
        )
        .filter(|_feature| {
            // TODO(antoyo): implement a way to get enabled feature in libgccjit.
            false
        })
        .map(|feature| Symbol::intern(feature))
        .collect()
}