use rustc_lint;
use rustc_driver::{self, driver, target_features, abort_on_err};
use rustc::session::{self, config};
use rustc::hir::def_id::{DefId, DefIndex, DefIndexAddressSpace, CrateNum, LOCAL_CRATE};
use rustc::hir::def::Def;
use rustc::hir::{self, HirVec};
use rustc::middle::cstore::CrateStore;
use rustc::middle::privacy::AccessLevels;
use rustc::ty::{self, TyCtxt, AllArenas};
use rustc::hir::map as hir_map;
use rustc::lint::{self, LintPass};
use rustc::session::config::ErrorOutputType;
use rustc::util::nodemap::{FxHashMap, FxHashSet};
use rustc_resolve as resolve;
use rustc_metadata::creader::CrateLoader;
use rustc_metadata::cstore::CStore;
use rustc_target::spec::TargetTriple;

use syntax::ast::{self, Ident, NodeId};
use syntax::source_map;
use syntax::feature_gate::UnstableFeatures;
use syntax::json::JsonEmitter;
use syntax::ptr::P;
use syntax::symbol::keywords;
use syntax_pos::DUMMY_SP;
use errors::{self, FatalError};
use errors::emitter::{Emitter, EmitterWriter};
use parking_lot::ReentrantMutex;

use std::cell::RefCell;
use std::mem;
use rustc_data_structures::sync::{self, Lrc};
use std::rc::Rc;
use std::sync::Arc;

use visit_ast::RustdocVisitor;
use config::{Options as RustdocOptions, RenderOptions};
use clean;
use clean::{get_path_for_type, Clean, MAX_DEF_ID, AttributesExt};
use html::render::RenderInfo;
use passes;

pub use rustc::session::config::{Input, Options, CodegenOptions};
pub use rustc::session::search_paths::SearchPath;

pub type ExternalPaths = FxHashMap<DefId, (Vec<String>, clean::TypeKind)>;

pub struct DocContext<'a, 'tcx: 'a, 'rcx: 'a> {
    pub tcx: TyCtxt<'a, 'tcx, 'tcx>,
    pub resolver: &'a RefCell<resolve::Resolver<'rcx>>,
    /// The stack of module NodeIds up till this point
    pub crate_name: Option<String>,
    pub cstore: Rc<CStore>,
    // Note that external items for which `doc(hidden)` applies to are shown as
    // non-reachable while local items aren't. This is because we're reusing
    // the access levels from crateanalysis.
    /// Later on moved into `html::render::CACHE_KEY`
    pub renderinfo: RefCell<RenderInfo>,
    /// Later on moved through `clean::Crate` into `html::render::CACHE_KEY`
    pub external_traits: Arc<ReentrantMutex<RefCell<FxHashMap<DefId, clean::Trait>>>>,
    /// Used while populating `external_traits` to ensure we don't process the same trait twice at
    /// the same time.
    pub active_extern_traits: RefCell<Vec<DefId>>,
    // The current set of type and lifetime substitutions,
    // for expanding type aliases at the HIR level:

    /// Table type parameter definition -> substituted type
    pub ty_substs: RefCell<FxHashMap<Def, clean::Type>>,
    /// Table node id of lifetime parameter definition -> substituted lifetime
    pub lt_substs: RefCell<FxHashMap<DefId, clean::Lifetime>>,
    /// Table DefId of `impl Trait` in argument position -> bounds
    pub impl_trait_bounds: RefCell<FxHashMap<DefId, Vec<clean::GenericBound>>>,
    pub send_trait: Option<DefId>,
    pub fake_def_ids: RefCell<FxHashMap<CrateNum, DefId>>,
    pub all_fake_def_ids: RefCell<FxHashSet<DefId>>,
    /// Maps (type_id, trait_id) -> auto trait impl
    pub generated_synthetics: RefCell<FxHashSet<(DefId, DefId)>>,
    pub all_traits: Vec<DefId>,
}

impl<'a, 'tcx, 'rcx> DocContext<'a, 'tcx, 'rcx> {
    pub fn sess(&self) -> &session::Session {
        &self.tcx.sess
    }

    /// Call the closure with the given parameters set as
    /// the substitutions for a type alias' RHS.
    pub fn enter_alias<F, R>(&self,
                             ty_substs: FxHashMap<Def, clean::Type>,
                             lt_substs: FxHashMap<DefId, clean::Lifetime>,
                             f: F) -> R
    where F: FnOnce() -> R {
        let (old_tys, old_lts) =
            (mem::replace(&mut *self.ty_substs.borrow_mut(), ty_substs),
             mem::replace(&mut *self.lt_substs.borrow_mut(), lt_substs));
        let r = f();
        *self.ty_substs.borrow_mut() = old_tys;
        *self.lt_substs.borrow_mut() = old_lts;
        r
    }

    // This is an ugly hack, but it's the simplest way to handle synthetic impls without greatly
    // refactoring either librustdoc or librustc. In particular, allowing new DefIds to be
    // registered after the AST is constructed would require storing the defid mapping in a
    // RefCell, decreasing the performance for normal compilation for very little gain.
    //
    // Instead, we construct 'fake' def ids, which start immediately after the last DefId in
    // DefIndexAddressSpace::Low. In the Debug impl for clean::Item, we explicitly check for fake
    // def ids, as we'll end up with a panic if we use the DefId Debug impl for fake DefIds
    pub fn next_def_id(&self, crate_num: CrateNum) -> DefId {
        let start_def_id = {
            let next_id = if crate_num == LOCAL_CRATE {
                self.tcx
                    .hir()
                    .definitions()
                    .def_path_table()
                    .next_id(DefIndexAddressSpace::Low)
            } else {
                self.cstore
                    .def_path_table(crate_num)
                    .next_id(DefIndexAddressSpace::Low)
            };

            DefId {
                krate: crate_num,
                index: next_id,
            }
        };

        let mut fake_ids = self.fake_def_ids.borrow_mut();

        let def_id = fake_ids.entry(crate_num).or_insert(start_def_id).clone();
        fake_ids.insert(
            crate_num,
            DefId {
                krate: crate_num,
                index: DefIndex::from_array_index(
                    def_id.index.as_array_index() + 1,
                    def_id.index.address_space(),
                ),
            },
        );

        MAX_DEF_ID.with(|m| {
            m.borrow_mut()
                .entry(def_id.krate.clone())
                .or_insert(start_def_id);
        });

        self.all_fake_def_ids.borrow_mut().insert(def_id);

        def_id.clone()
    }

    /// Like the function of the same name on the HIR map, but skips calling it on fake DefIds.
    /// (This avoids a slice-index-out-of-bounds panic.)
    pub fn as_local_node_id(&self, def_id: DefId) -> Option<NodeId> {
        if self.all_fake_def_ids.borrow().contains(&def_id) {
            None
        } else {
            self.tcx.hir().as_local_node_id(def_id)
        }
    }

    pub fn get_real_ty<F>(&self,
                          def_id: DefId,
                          def_ctor: &F,
                          real_name: &Option<Ident>,
                          generics: &ty::Generics,
    ) -> hir::Ty
    where F: Fn(DefId) -> Def {
        let path = get_path_for_type(self.tcx, def_id, def_ctor);
        let mut segments = path.segments.into_vec();
        let last = segments.pop().expect("segments were empty");

        segments.push(hir::PathSegment::new(
            real_name.unwrap_or(last.ident),
            None,
            None,
            self.generics_to_path_params(generics.clone()),
            false,
        ));

        let new_path = hir::Path {
            span: path.span,
            def: path.def,
            segments: HirVec::from_vec(segments),
        };

        hir::Ty {
            id: ast::DUMMY_NODE_ID,
            node: hir::TyKind::Path(hir::QPath::Resolved(None, P(new_path))),
            span: DUMMY_SP,
            hir_id: hir::DUMMY_HIR_ID,
        }
    }

    pub fn generics_to_path_params(&self, generics: ty::Generics) -> hir::GenericArgs {
        let mut args = vec![];

        for param in generics.params.iter() {
            match param.kind {
                ty::GenericParamDefKind::Lifetime => {
                    let name = if param.name == "" {
                        hir::ParamName::Plain(keywords::StaticLifetime.ident())
                    } else {
                        hir::ParamName::Plain(ast::Ident::from_interned_str(param.name))
                    };

                    args.push(hir::GenericArg::Lifetime(hir::Lifetime {
                        id: ast::DUMMY_NODE_ID,
                        span: DUMMY_SP,
                        name: hir::LifetimeName::Param(name),
                    }));
                }
                ty::GenericParamDefKind::Type {..} => {
                    args.push(hir::GenericArg::Type(self.ty_param_to_ty(param.clone())));
                }
            }
        }

        hir::GenericArgs {
            args: HirVec::from_vec(args),
            bindings: HirVec::new(),
            parenthesized: false,
        }
    }

    pub fn ty_param_to_ty(&self, param: ty::GenericParamDef) -> hir::Ty {
        debug!("ty_param_to_ty({:?}) {:?}", param, param.def_id);
        hir::Ty {
            id: ast::DUMMY_NODE_ID,
            node: hir::TyKind::Path(hir::QPath::Resolved(
                None,
                P(hir::Path {
                    span: DUMMY_SP,
                    def: Def::TyParam(param.def_id),
                    segments: HirVec::from_vec(vec![
                        hir::PathSegment::from_ident(Ident::from_interned_str(param.name))
                    ]),
                }),
            )),
            span: DUMMY_SP,
            hir_id: hir::DUMMY_HIR_ID,
        }
    }
}

pub trait DocAccessLevels {
    fn is_doc_reachable(&self, did: DefId) -> bool;
}

impl DocAccessLevels for AccessLevels<DefId> {
    fn is_doc_reachable(&self, did: DefId) -> bool {
        self.is_public(did)
    }
}

/// Creates a new diagnostic `Handler` that can be used to emit warnings and errors.
///
/// If the given `error_format` is `ErrorOutputType::Json` and no `SourceMap` is given, a new one
/// will be created for the handler.
pub fn new_handler(error_format: ErrorOutputType,
                   source_map: Option<Lrc<source_map::SourceMap>>,
                   treat_err_as_bug: bool,
                   ui_testing: bool,
) -> errors::Handler {
    // rustdoc doesn't override (or allow to override) anything from this that is relevant here, so
    // stick to the defaults
    let sessopts = Options::default();
    let emitter: Box<dyn Emitter + sync::Send> = match error_format {
        ErrorOutputType::HumanReadable(color_config) => Box::new(
            EmitterWriter::stderr(
                color_config,
                source_map.map(|cm| cm as _),
                false,
                sessopts.debugging_opts.teach,
            ).ui_testing(ui_testing)
        ),
        ErrorOutputType::Json(pretty) => {
            let source_map = source_map.unwrap_or_else(
                || Lrc::new(source_map::SourceMap::new(sessopts.file_path_mapping())));
            Box::new(
                JsonEmitter::stderr(
                    None,
                    source_map,
                    pretty,
                ).ui_testing(ui_testing)
            )
        },
        ErrorOutputType::Short(color_config) => Box::new(
            EmitterWriter::stderr(
                color_config,
                source_map.map(|cm| cm as _),
                true,
                false)
        ),
    };

    errors::Handler::with_emitter_and_flags(
        emitter,
        errors::HandlerFlags {
            can_emit_warnings: true,
            treat_err_as_bug,
            report_delayed_bugs: false,
            external_macro_backtrace: false,
            ..Default::default()
        },
    )
}

pub fn run_core(options: RustdocOptions) -> (clean::Crate, RenderInfo, RenderOptions, Vec<String>) {
    // Parse, resolve, and typecheck the given crate.

    let RustdocOptions {
        input,
        crate_name,
        error_format,
        libs,
        externs,
        cfgs,
        codegen_options,
        debugging_options,
        target,
        edition,
        maybe_sysroot,
        lint_opts,
        describe_lints,
        lint_cap,
        mut default_passes,
        mut manual_passes,
        display_warnings,
        render_options,
        ..
    } = options;

    let cpath = Some(input.clone());
    let input = Input::File(input);

    let intra_link_resolution_failure_name = lint::builtin::INTRA_DOC_LINK_RESOLUTION_FAILURE.name;
    let warnings_lint_name = lint::builtin::WARNINGS.name;
    let missing_docs = rustc_lint::builtin::MISSING_DOCS.name;
    let missing_doc_example = rustc_lint::builtin::MISSING_DOC_CODE_EXAMPLES.name;
    let private_doc_tests = rustc_lint::builtin::PRIVATE_DOC_TESTS.name;

    // In addition to those specific lints, we also need to whitelist those given through
    // command line, otherwise they'll get ignored and we don't want that.
    let mut whitelisted_lints = vec![warnings_lint_name.to_owned(),
                                     intra_link_resolution_failure_name.to_owned(),
                                     missing_docs.to_owned(),
                                     missing_doc_example.to_owned(),
                                     private_doc_tests.to_owned()];

    whitelisted_lints.extend(lint_opts.iter().map(|(lint, _)| lint).cloned());

    let lints = lint::builtin::HardwiredLints.get_lints()
                    .into_iter()
                    .chain(rustc_lint::SoftLints.get_lints().into_iter())
                    .filter_map(|lint| {
                        if lint.name == warnings_lint_name ||
                           lint.name == intra_link_resolution_failure_name {
                            None
                        } else {
                            Some((lint.name_lower(), lint::Allow))
                        }
                    })
                    .chain(lint_opts.into_iter())
                    .collect::<Vec<_>>();

    let host_triple = TargetTriple::from_triple(config::host_triple());
    // plays with error output here!
    let sessopts = config::Options {
        maybe_sysroot,
        search_paths: libs,
        crate_types: vec![config::CrateType::Rlib],
        lint_opts: if !display_warnings {
            lints
        } else {
            vec![]
        },
        lint_cap: Some(lint_cap.unwrap_or_else(|| lint::Forbid)),
        cg: codegen_options,
        externs,
        target_triple: target.unwrap_or(host_triple),
        // Ensure that rustdoc works even if rustc is feature-staged
        unstable_features: UnstableFeatures::Allow,
        actually_rustdoc: true,
        debugging_opts: debugging_options.clone(),
        error_format,
        edition,
        describe_lints,
        ..Options::default()
    };
    driver::spawn_thread_pool(sessopts, move |sessopts| {
        let source_map = Lrc::new(source_map::SourceMap::new(sessopts.file_path_mapping()));
        let diagnostic_handler = new_handler(error_format,
                                             Some(source_map.clone()),
                                             debugging_options.treat_err_as_bug,
                                             debugging_options.ui_testing);

        let mut sess = session::build_session_(
            sessopts, cpath, diagnostic_handler, source_map,
        );

        lint::builtin::HardwiredLints.get_lints()
                                     .into_iter()
                                     .chain(rustc_lint::SoftLints.get_lints().into_iter())
                                     .filter_map(|lint| {
                                         // We don't want to whitelist *all* lints so let's
                                         // ignore those ones.
                                         if whitelisted_lints.iter().any(|l| &lint.name == l) {
                                             None
                                         } else {
                                             Some(lint)
                                         }
                                     })
                                     .for_each(|l| {
                                         sess.driver_lint_caps.insert(lint::LintId::of(l),
                                                                      lint::Allow);
                                     });

        let codegen_backend = rustc_driver::get_codegen_backend(&sess);
        let cstore = Rc::new(CStore::new(codegen_backend.metadata_loader()));
        rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));

        let mut cfg = config::build_configuration(&sess, config::parse_cfgspecs(cfgs));
        target_features::add_configuration(&mut cfg, &sess, &*codegen_backend);
        sess.parse_sess.config = cfg;

        let control = &driver::CompileController::basic();

        let krate = match driver::phase_1_parse_input(control, &sess, &input) {
            Ok(krate) => krate,
            Err(mut e) => {
                e.emit();
                FatalError.raise();
            }
        };

        let name = match crate_name {
            Some(ref crate_name) => crate_name.clone(),
            None => ::rustc_codegen_utils::link::find_crate_name(Some(&sess), &krate.attrs, &input),
        };

        let mut crate_loader = CrateLoader::new(&sess, &cstore, &name);

        let resolver_arenas = resolve::Resolver::arenas();
        let result = driver::phase_2_configure_and_expand_inner(&sess,
                                                        &cstore,
                                                        krate,
                                                        None,
                                                        &name,
                                                        None,
                                                        resolve::MakeGlobMap::No,
                                                        &resolver_arenas,
                                                        &mut crate_loader,
                                                        |_| Ok(()));
        let driver::InnerExpansionResult {
            mut hir_forest,
            resolver,
            ..
        } = abort_on_err(result, &sess);

        // We need to hold on to the complete resolver, so we clone everything
        // for the analysis passes to use. Suboptimal, but necessary in the
        // current architecture.
        let defs = resolver.definitions.clone();
        let resolutions = ty::Resolutions {
            freevars: resolver.freevars.clone(),
            export_map: resolver.export_map.clone(),
            trait_map: resolver.trait_map.clone(),
            maybe_unused_trait_imports: resolver.maybe_unused_trait_imports.clone(),
            maybe_unused_extern_crates: resolver.maybe_unused_extern_crates.clone(),
            extern_prelude: resolver.extern_prelude.iter().map(|(ident, entry)| {
                (ident.name, entry.introduced_by_item)
            }).collect(),
        };
        let analysis = ty::CrateAnalysis {
            glob_map: if resolver.make_glob_map { Some(resolver.glob_map.clone()) } else { None },
        };

        let mut arenas = AllArenas::new();
        let hir_map = hir_map::map_crate(&sess, &*cstore, &mut hir_forest, &defs);
        let output_filenames = driver::build_output_filenames(&input,
                                                            &None,
                                                            &None,
                                                            &[],
                                                            &sess);

        let resolver = RefCell::new(resolver);
        abort_on_err(driver::phase_3_run_analysis_passes(&*codegen_backend,
                                                        control,
                                                        &sess,
                                                        &*cstore,
                                                        hir_map,
                                                        analysis,
                                                        resolutions,
                                                        &mut arenas,
                                                        &name,
                                                        &output_filenames,
                                                        |tcx, _, _, result| {
            if result.is_err() {
                sess.fatal("Compilation failed, aborting rustdoc");
            }

            let access_levels = tcx.privacy_access_levels(LOCAL_CRATE);

            // Convert from a NodeId set to a DefId set since we don't always have easy access
            // to the map from defid -> nodeid
            let access_levels = AccessLevels {
                map: access_levels.map.iter()
                                    .map(|(&k, &v)| (tcx.hir().local_def_id(k), v))
                                    .collect()
            };

            let send_trait = if crate_name == Some("core".to_string()) {
                clean::path_to_def_local(&tcx, &["marker", "Send"])
            } else {
                clean::path_to_def(&tcx, &["core", "marker", "Send"])
            };

            let mut renderinfo = RenderInfo::default();
            renderinfo.access_levels = access_levels;

            let ctxt = DocContext {
                tcx,
                resolver: &resolver,
                crate_name,
                cstore: cstore.clone(),
                external_traits: Default::default(),
                active_extern_traits: Default::default(),
                renderinfo: RefCell::new(renderinfo),
                ty_substs: Default::default(),
                lt_substs: Default::default(),
                impl_trait_bounds: Default::default(),
                send_trait: send_trait,
                fake_def_ids: Default::default(),
                all_fake_def_ids: Default::default(),
                generated_synthetics: Default::default(),
                all_traits: tcx.all_traits(LOCAL_CRATE).to_vec(),
            };
            debug!("crate: {:?}", tcx.hir().krate());

            let mut krate = {
                let mut v = RustdocVisitor::new(&ctxt);
                v.visit(tcx.hir().krate());
                v.clean(&ctxt)
            };

            fn report_deprecated_attr(name: &str, diag: &errors::Handler) {
                let mut msg = diag.struct_warn(&format!("the `#![doc({})]` attribute is \
                                                         considered deprecated", name));
                msg.warn("please see https://github.com/rust-lang/rust/issues/44136");

                if name == "no_default_passes" {
                    msg.help("you may want to use `#![doc(document_private_items)]`");
                }

                msg.emit();
            }

            // Process all of the crate attributes, extracting plugin metadata along
            // with the passes which we are supposed to run.
            for attr in krate.module.as_ref().unwrap().attrs.lists("doc") {
                let diag = ctxt.sess().diagnostic();

                let name = attr.name().map(|s| s.as_str());
                let name = name.as_ref().map(|s| &s[..]);
                if attr.is_word() {
                    if name == Some("no_default_passes") {
                        report_deprecated_attr("no_default_passes", diag);
                        if default_passes == passes::DefaultPassOption::Default {
                            default_passes = passes::DefaultPassOption::None;
                        }
                    }
                } else if let Some(value) = attr.value_str() {
                    let sink = match name {
                        Some("passes") => {
                            report_deprecated_attr("passes = \"...\"", diag);
                            &mut manual_passes
                        },
                        Some("plugins") => {
                            report_deprecated_attr("plugins = \"...\"", diag);
                            eprintln!("WARNING: #![doc(plugins = \"...\")] no longer functions; \
                                      see CVE-2018-1000622");
                            continue
                        },
                        _ => continue,
                    };
                    for p in value.as_str().split_whitespace() {
                        sink.push(p.to_string());
                    }
                }

                if attr.is_word() && name == Some("document_private_items") {
                    if default_passes == passes::DefaultPassOption::Default {
                        default_passes = passes::DefaultPassOption::Private;
                    }
                }
            }

            let mut passes: Vec<String> =
                passes::defaults(default_passes).iter().map(|p| p.to_string()).collect();
            passes.extend(manual_passes);

            for pass in &passes {
                // the "unknown pass" error will be reported when late passes are run
                if let Some(pass) = passes::find_pass(pass).and_then(|p| p.early_fn()) {
                    krate = pass(krate, &ctxt);
                }
            }

            ctxt.sess().abort_if_errors();

            (krate, ctxt.renderinfo.into_inner(), render_options, passes)
        }), &sess)
    })
}
