use rustc_lint;
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, HirId, HirVec};
use rustc::middle::cstore::CrateStore;
use rustc::middle::privacy::AccessLevels;
use rustc::ty::{self, TyCtxt};
use rustc::lint::{self, LintPass};
use rustc::session::config::ErrorOutputType;
use rustc::session::DiagnosticOutput;
use rustc::util::nodemap::{FxHashMap, FxHashSet};
use rustc_interface::interface;
use rustc_driver::abort_on_err;
use rustc_resolve as resolve;
use rustc_metadata::cstore::CStore;
use rustc_target::spec::TargetTriple;

use syntax::ast::{self, Ident};
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;
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::sync::Arc;
use std::rc::Rc;

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

use crate::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<'tcx> {

    pub tcx: TyCtxt<'tcx, 'tcx, 'tcx>,
    pub resolver: Rc<Option<RefCell<interface::BoxedResolver>>>,
    /// The stack of module NodeIds up till this point
    pub crate_name: Option<String>,
    pub cstore: Lrc<CStore>,
    /// 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 `NodeId` of lifetime parameter definition -> substituted lifetime
    pub lt_substs: RefCell<FxHashMap<DefId, clean::Lifetime>>,
    /// Table node id of const parameter definition -> substituted const
    pub ct_substs: RefCell<FxHashMap<Def, clean::Constant>>,
    /// 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<'tcx> DocContext<'tcx> {
    pub fn sess(&self) -> &session::Session {
        &self.tcx.sess
    }

    pub fn enter_resolver<F, R>(&self, f: F) -> R
    where F: FnOnce(&mut resolve::Resolver<'_>) -> R {
        let resolver = &*self.resolver;
        let resolver = resolver.as_ref().unwrap();
        resolver.borrow_mut().access(f)
    }

    /// 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>,
                             ct_substs: FxHashMap<Def, clean::Constant>,
                             f: F) -> R
    where F: FnOnce() -> R {
        let (old_tys, old_lts, old_cts) = (
            mem::replace(&mut *self.ty_substs.borrow_mut(), ty_substs),
            mem::replace(&mut *self.lt_substs.borrow_mut(), lt_substs),
            mem::replace(&mut *self.ct_substs.borrow_mut(), ct_substs),
        );
        let r = f();
        *self.ty_substs.borrow_mut() = old_tys;
        *self.lt_substs.borrow_mut() = old_lts;
        *self.ct_substs.borrow_mut() = old_cts;
        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_hir_id(&self, def_id: DefId) -> Option<HirId> {
        if self.all_fake_def_ids.borrow().contains(&def_id) {
            None
        } else {
            self.tcx.hir().as_local_hir_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 {
            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 {
                        hir_id: hir::DUMMY_HIR_ID,
                        span: DUMMY_SP,
                        name: hir::LifetimeName::Param(name),
                    }));
                }
                ty::GenericParamDefKind::Type { .. } => {
                    args.push(hir::GenericArg::Type(self.ty_param_to_ty(param.clone())));
                }
                ty::GenericParamDefKind::Const => {
                    args.push(hir::GenericArg::Const(hir::ConstArg {
                        value: hir::AnonConst {
                            hir_id: hir::DUMMY_HIR_ID,
                            body: hir::BodyId {
                                hir_id: hir::DUMMY_HIR_ID,
                            }
                        },
                        span: DUMMY_SP,
                    }))
                }
            }
        }

        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 {
            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: Option<usize>,
                   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(kind) => {
            let (short, color_config) = kind.unzip();
            Box::new(
                EmitterWriter::stderr(
                    color_config,
                    source_map.map(|cm| cm as _),
                    short,
                    sessopts.debugging_opts.teach,
                ).ui_testing(ui_testing)
            )
        },
        ErrorOutputType::Json { pretty, json_rendered } => {
            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,
                    json_rendered,
                ).ui_testing(ui_testing)
            )
        },
    };

    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())
    };

    let lint_opts = lints().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 lint_caps = lints().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::LintId::of(lint), lint::Allow))
        }
    }).collect();

    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 {
            lint_opts
        } 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()
    };

    let config = interface::Config {
        opts: sessopts,
        crate_cfg: config::parse_cfgspecs(cfgs),
        input,
        input_path: cpath,
        output_file: None,
        output_dir: None,
        file_loader: None,
        diagnostic_output: DiagnosticOutput::Default,
        stderr: None,
        crate_name: crate_name.clone(),
        lint_caps,
    };

    interface::run_compiler_in_existing_thread_pool(config, |compiler| {
        let sess = compiler.session();

        // We need to hold on to the complete resolver, so we cause everything to be
        // cloned for the analysis passes to use. Suboptimal, but necessary in the
        // current architecture.
        let resolver = abort_on_err(compiler.expansion(), sess).peek().1.clone();

        if sess.err_count() > 0 {
            sess.fatal("Compilation failed, aborting rustdoc");
        }

        let mut global_ctxt = abort_on_err(compiler.global_ctxt(), sess).take();

        global_ctxt.enter(|tcx| {
            tcx.analysis(LOCAL_CRATE).ok();

            // Abort if there were any errors so far
            sess.abort_if_errors();

            let access_levels = tcx.privacy_access_levels(LOCAL_CRATE);
            // Convert from a HirId set to a DefId set since we don't always have easy access
            // to the map from defid -> hirid
            let access_levels = AccessLevels {
                map: access_levels.map.iter()
                                    .map(|(&k, &v)| (tcx.hir().local_def_id_from_hir_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,
                crate_name,
                cstore: compiler.cstore().clone(),
                external_traits: Default::default(),
                active_extern_traits: Default::default(),
                renderinfo: RefCell::new(renderinfo),
                ty_substs: Default::default(),
                lt_substs: Default::default(),
                ct_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_or_empty();
                if attr.is_word() {
                    if name == "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.get() {
                        "passes" => {
                            report_deprecated_attr("passes = \"...\"", diag);
                            &mut manual_passes
                        },
                        "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 == "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);

            info!("Executing passes");

            for pass_name in &passes {
                match passes::find_pass(pass_name).map(|p| p.pass) {
                    Some(pass) => {
                        debug!("running pass {}", pass_name);
                        krate = pass(krate, &ctxt);
                    }
                    None => error!("unknown pass {}, skipping", *pass_name),
                }
            }

            ctxt.sess().abort_if_errors();

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