// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.

use crate::args::TsConfig;
use crate::args::TypeCheckMode;
use crate::cache::FastInsecureHasher;
use crate::node;
use crate::npm::CliNpmResolver;
use crate::util::checksum;
use crate::util::path::mapped_specifier_for_tsc;

use deno_ast::MediaType;
use deno_core::anyhow::anyhow;
use deno_core::anyhow::Context;
use deno_core::ascii_str;
use deno_core::error::AnyError;
use deno_core::located_script_name;
use deno_core::op2;
use deno_core::resolve_url_or_path;
use deno_core::serde::Deserialize;
use deno_core::serde::Deserializer;
use deno_core::serde::Serialize;
use deno_core::serde::Serializer;
use deno_core::serde_json::json;
use deno_core::serde_v8;
use deno_core::JsRuntime;
use deno_core::ModuleSpecifier;
use deno_core::OpState;
use deno_core::RuntimeOptions;
use deno_graph::GraphKind;
use deno_graph::Module;
use deno_graph::ModuleGraph;
use deno_graph::ResolutionResolved;
use deno_runtime::deno_node::NodeResolution;
use deno_runtime::deno_node::NodeResolutionMode;
use deno_runtime::deno_node::NodeResolver;
use deno_runtime::permissions::PermissionsContainer;
use deno_semver::npm::NpmPackageReqReference;
use lsp_types::Url;
use once_cell::sync::Lazy;
use std::borrow::Cow;
use std::collections::HashMap;
use std::fmt;
use std::path::Path;
use std::path::PathBuf;
use std::sync::Arc;

mod diagnostics;

pub use self::diagnostics::Diagnostic;
pub use self::diagnostics::DiagnosticCategory;
pub use self::diagnostics::Diagnostics;
pub use self::diagnostics::Position;

pub static COMPILER_SNAPSHOT: Lazy<Box<[u8]>> = Lazy::new(
  #[cold]
  #[inline(never)]
  || {
    static COMPRESSED_COMPILER_SNAPSHOT: &[u8] =
      include_bytes!(concat!(env!("OUT_DIR"), "/COMPILER_SNAPSHOT.bin"));

    // NOTE(bartlomieju): Compressing the TSC snapshot in debug build took
    // ~45s on M1 MacBook Pro; without compression it took ~1s.
    // Thus we're not using compressed snapshot, trading off
    // a lot of build time for some startup time in debug build.
    #[cfg(debug_assertions)]
    return COMPRESSED_COMPILER_SNAPSHOT.to_vec().into_boxed_slice();

    #[cfg(not(debug_assertions))]
    zstd::bulk::decompress(
      &COMPRESSED_COMPILER_SNAPSHOT[4..],
      u32::from_le_bytes(COMPRESSED_COMPILER_SNAPSHOT[0..4].try_into().unwrap())
        as usize,
    )
    .unwrap()
    .into_boxed_slice()
  },
);

pub fn get_types_declaration_file_text() -> String {
  let mut assets = get_asset_texts_from_new_runtime()
    .unwrap()
    .into_iter()
    .map(|a| (a.specifier, a.text))
    .collect::<HashMap<_, _>>();

  let lib_names = vec![
    "deno.ns",
    "deno.console",
    "deno.url",
    "deno.web",
    "deno.fetch",
    "deno.webgpu",
    "deno.websocket",
    "deno.webstorage",
    "deno.canvas",
    "deno.crypto",
    "deno.broadcast_channel",
    "deno.net",
    "deno.shared_globals",
    "deno.cache",
    "deno.window",
    "deno.unstable",
  ];

  lib_names
    .into_iter()
    .map(|name| {
      let asset_url = format!("asset:///lib.{name}.d.ts");
      assets.remove(&asset_url).unwrap()
    })
    .collect::<Vec<_>>()
    .join("\n")
}

fn get_asset_texts_from_new_runtime() -> Result<Vec<AssetText>, AnyError> {
  deno_core::extension!(
    deno_cli_tsc,
    ops = [
      op_create_hash,
      op_emit,
      op_is_node_file,
      op_load,
      op_resolve,
      op_respond,
    ]
  );

  // the assets are stored within the typescript isolate, so take them out of there
  let mut runtime = JsRuntime::new(RuntimeOptions {
    startup_snapshot: Some(compiler_snapshot()),
    extensions: vec![deno_cli_tsc::init_ops()],
    ..Default::default()
  });
  let global = runtime
    .execute_script("get_assets.js", ascii_str!("globalThis.getAssets()"))?;
  let scope = &mut runtime.handle_scope();
  let local = deno_core::v8::Local::new(scope, global);
  Ok(serde_v8::from_v8::<Vec<AssetText>>(scope, local)?)
}

pub fn compiler_snapshot() -> &'static [u8] {
  &COMPILER_SNAPSHOT
}

macro_rules! inc {
  ($e:expr) => {
    include_str!(concat!("./dts/", $e))
  };
}

/// Contains static assets that are not preloaded in the compiler snapshot.
///
/// We lazily load these because putting them in the compiler snapshot will
/// increase memory usage when not used (last time checked by about 0.5MB).
pub static LAZILY_LOADED_STATIC_ASSETS: Lazy<
  HashMap<&'static str, &'static str>,
> = Lazy::new(|| {
  ([
    (
      "lib.dom.asynciterable.d.ts",
      inc!("lib.dom.asynciterable.d.ts"),
    ),
    ("lib.dom.d.ts", inc!("lib.dom.d.ts")),
    ("lib.dom.extras.d.ts", inc!("lib.dom.extras.d.ts")),
    ("lib.dom.iterable.d.ts", inc!("lib.dom.iterable.d.ts")),
    ("lib.es6.d.ts", inc!("lib.es6.d.ts")),
    ("lib.es2016.full.d.ts", inc!("lib.es2016.full.d.ts")),
    ("lib.es2017.full.d.ts", inc!("lib.es2017.full.d.ts")),
    ("lib.es2018.full.d.ts", inc!("lib.es2018.full.d.ts")),
    ("lib.es2019.full.d.ts", inc!("lib.es2019.full.d.ts")),
    ("lib.es2020.full.d.ts", inc!("lib.es2020.full.d.ts")),
    ("lib.es2021.full.d.ts", inc!("lib.es2021.full.d.ts")),
    ("lib.es2022.full.d.ts", inc!("lib.es2022.full.d.ts")),
    ("lib.esnext.full.d.ts", inc!("lib.esnext.full.d.ts")),
    ("lib.scripthost.d.ts", inc!("lib.scripthost.d.ts")),
    ("lib.webworker.d.ts", inc!("lib.webworker.d.ts")),
    (
      "lib.webworker.importscripts.d.ts",
      inc!("lib.webworker.importscripts.d.ts"),
    ),
    (
      "lib.webworker.iterable.d.ts",
      inc!("lib.webworker.iterable.d.ts"),
    ),
    (
      // Special file that can be used to inject the @types/node package.
      // This is used for `node:` specifiers.
      "node_types.d.ts",
      "/// <reference types=\"npm:@types/node\" />\n",
    ),
  ])
  .iter()
  .cloned()
  .collect()
});

/// A structure representing stats from a type check operation for a graph.
#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct Stats(pub Vec<(String, u32)>);

impl<'de> Deserialize<'de> for Stats {
  fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
  where
    D: Deserializer<'de>,
  {
    let items: Vec<(String, u32)> = Deserialize::deserialize(deserializer)?;
    Ok(Stats(items))
  }
}

impl Serialize for Stats {
  fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
  where
    S: Serializer,
  {
    Serialize::serialize(&self.0, serializer)
  }
}

impl fmt::Display for Stats {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    writeln!(f, "Compilation statistics:")?;
    for (key, value) in self.0.clone() {
      writeln!(f, "  {key}: {value}")?;
    }

    Ok(())
  }
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct AssetText {
  pub specifier: String,
  pub text: String,
}

/// Retrieve a static asset that are included in the binary.
fn get_lazily_loaded_asset(asset: &str) -> Option<&'static str> {
  LAZILY_LOADED_STATIC_ASSETS.get(asset).map(|s| s.to_owned())
}

fn get_maybe_hash(
  maybe_source: Option<&str>,
  hash_data: u64,
) -> Option<String> {
  maybe_source.map(|source| get_hash(source, hash_data))
}

fn get_hash(source: &str, hash_data: u64) -> String {
  FastInsecureHasher::new()
    .write_str(source)
    .write_u64(hash_data)
    .finish()
    .to_string()
}

/// Hash the URL so it can be sent to `tsc` in a supportable way
fn hash_url(specifier: &ModuleSpecifier, media_type: MediaType) -> String {
  let hash = checksum::gen(&[specifier.path().as_bytes()]);
  format!(
    "{}:///{}{}",
    specifier.scheme(),
    hash,
    media_type.as_ts_extension()
  )
}

/// If the provided URLs derivable tsc media type doesn't match the media type,
/// we will add an extension to the output.  This is to avoid issues with
/// specifiers that don't have extensions, that tsc refuses to emit because they
/// think a `.js` version exists, when it doesn't.
fn maybe_remap_specifier(
  specifier: &ModuleSpecifier,
  media_type: MediaType,
) -> Option<String> {
  let path = if specifier.scheme() == "file" {
    if let Ok(path) = specifier.to_file_path() {
      path
    } else {
      PathBuf::from(specifier.path())
    }
  } else {
    PathBuf::from(specifier.path())
  };
  if path.extension().is_none() {
    Some(format!("{}{}", specifier, media_type.as_ts_extension()))
  } else {
    None
  }
}

#[derive(Debug, Clone, Default, Eq, PartialEq)]
pub struct EmittedFile {
  pub data: String,
  pub maybe_specifiers: Option<Vec<ModuleSpecifier>>,
  pub media_type: MediaType,
}

#[derive(Debug)]
pub struct RequestNpmState {
  pub node_resolver: Arc<NodeResolver>,
  pub npm_resolver: Arc<dyn CliNpmResolver>,
}

/// A structure representing a request to be sent to the tsc runtime.
#[derive(Debug)]
pub struct Request {
  /// The TypeScript compiler options which will be serialized and sent to
  /// tsc.
  pub config: TsConfig,
  /// Indicates to the tsc runtime if debug logging should occur.
  pub debug: bool,
  pub graph: Arc<ModuleGraph>,
  pub hash_data: u64,
  pub maybe_npm: Option<RequestNpmState>,
  pub maybe_tsbuildinfo: Option<String>,
  /// A vector of strings that represent the root/entry point modules for the
  /// program.
  pub root_names: Vec<(ModuleSpecifier, MediaType)>,
  pub check_mode: TypeCheckMode,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct Response {
  /// Any diagnostics that have been returned from the checker.
  pub diagnostics: Diagnostics,
  /// If there was any build info associated with the exec request.
  pub maybe_tsbuildinfo: Option<String>,
  /// Statistics from the check.
  pub stats: Stats,
}

// TODO(bartlomieju): we have similar struct in `tsc.rs` - maybe at least change
// the name of the struct to avoid confusion?
#[derive(Debug)]
struct State {
  hash_data: u64,
  graph: Arc<ModuleGraph>,
  maybe_tsbuildinfo: Option<String>,
  maybe_response: Option<RespondArgs>,
  maybe_npm: Option<RequestNpmState>,
  remapped_specifiers: HashMap<String, ModuleSpecifier>,
  root_map: HashMap<String, ModuleSpecifier>,
  current_dir: PathBuf,
}

impl Default for State {
  fn default() -> Self {
    Self {
      hash_data: Default::default(),
      graph: Arc::new(ModuleGraph::new(GraphKind::All)),
      maybe_tsbuildinfo: Default::default(),
      maybe_response: Default::default(),
      maybe_npm: Default::default(),
      remapped_specifiers: Default::default(),
      root_map: Default::default(),
      current_dir: Default::default(),
    }
  }
}

impl State {
  pub fn new(
    graph: Arc<ModuleGraph>,
    hash_data: u64,
    maybe_npm: Option<RequestNpmState>,
    maybe_tsbuildinfo: Option<String>,
    root_map: HashMap<String, ModuleSpecifier>,
    remapped_specifiers: HashMap<String, ModuleSpecifier>,
    current_dir: PathBuf,
  ) -> Self {
    State {
      hash_data,
      graph,
      maybe_npm,
      maybe_tsbuildinfo,
      maybe_response: None,
      remapped_specifiers,
      root_map,
      current_dir,
    }
  }
}

fn normalize_specifier(
  specifier: &str,
  current_dir: &Path,
) -> Result<ModuleSpecifier, AnyError> {
  resolve_url_or_path(specifier, current_dir).map_err(|err| err.into())
}

#[op2]
#[string]
fn op_create_hash(s: &mut OpState, #[string] text: &str) -> String {
  op_create_hash_inner(s, text)
}

#[inline]
fn op_create_hash_inner(s: &mut OpState, text: &str) -> String {
  let state = s.borrow_mut::<State>();
  get_hash(text, state.hash_data)
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct EmitArgs {
  /// The text data/contents of the file.
  data: String,
  /// The _internal_ filename for the file.  This will be used to determine how
  /// the file is cached and stored.
  file_name: String,
}

#[op2]
fn op_emit(state: &mut OpState, #[serde] args: EmitArgs) -> bool {
  op_emit_inner(state, args)
}

#[inline]
fn op_emit_inner(state: &mut OpState, args: EmitArgs) -> bool {
  let state = state.borrow_mut::<State>();
  match args.file_name.as_ref() {
    "internal:///.tsbuildinfo" => state.maybe_tsbuildinfo = Some(args.data),
    _ => {
      if cfg!(debug_assertions) {
        panic!("Unhandled emit write: {}", args.file_name);
      }
    }
  }

  true
}

pub fn as_ts_script_kind(media_type: MediaType) -> i32 {
  match media_type {
    MediaType::JavaScript => 1,
    MediaType::Jsx => 2,
    MediaType::Mjs => 1,
    MediaType::Cjs => 1,
    MediaType::TypeScript => 3,
    MediaType::Mts => 3,
    MediaType::Cts => 3,
    MediaType::Dts => 3,
    MediaType::Dmts => 3,
    MediaType::Dcts => 3,
    MediaType::Tsx => 4,
    MediaType::Json => 6,
    MediaType::SourceMap
    | MediaType::TsBuildInfo
    | MediaType::Wasm
    | MediaType::Unknown => 0,
  }
}

pub const MISSING_DEPENDENCY_SPECIFIER: &str =
  "internal:///missing_dependency.d.ts";

#[derive(Debug, Serialize)]
#[serde(rename_all = "camelCase")]
struct LoadResponse {
  data: String,
  version: Option<String>,
  script_kind: i32,
}

#[op2]
#[serde]
fn op_load(
  state: &mut OpState,
  #[string] load_specifier: &str,
) -> Result<Option<LoadResponse>, AnyError> {
  op_load_inner(state, load_specifier)
}

fn op_load_inner(
  state: &mut OpState,
  load_specifier: &str,
) -> Result<Option<LoadResponse>, AnyError> {
  let state = state.borrow_mut::<State>();

  let specifier = normalize_specifier(load_specifier, &state.current_dir)
    .context("Error converting a string module specifier for \"op_load\".")?;

  let mut hash: Option<String> = None;
  let mut media_type = MediaType::Unknown;
  let graph = &state.graph;

  let data = if load_specifier == "internal:///.tsbuildinfo" {
    state.maybe_tsbuildinfo.as_deref().map(Cow::Borrowed)
  // in certain situations we return a "blank" module to tsc and we need to
  // handle the request for that module here.
  } else if load_specifier == MISSING_DEPENDENCY_SPECIFIER {
    None
  } else if let Some(name) = load_specifier.strip_prefix("asset:///") {
    let maybe_source = get_lazily_loaded_asset(name);
    hash = get_maybe_hash(maybe_source, state.hash_data);
    media_type = MediaType::from_str(load_specifier);
    maybe_source.map(Cow::Borrowed)
  } else {
    let specifier = if let Some(remapped_specifier) =
      state.remapped_specifiers.get(load_specifier)
    {
      remapped_specifier
    } else if let Some(remapped_specifier) = state.root_map.get(load_specifier)
    {
      remapped_specifier
    } else {
      &specifier
    };
    let maybe_source = if let Some(module) = graph.get(specifier) {
      match module {
        Module::Js(module) => {
          media_type = module.media_type;
          let source = module
            .fast_check_module()
            .map(|m| &*m.source)
            .unwrap_or(&*module.source);
          Some(Cow::Borrowed(source))
        }
        Module::Json(module) => {
          media_type = MediaType::Json;
          Some(Cow::Borrowed(&*module.source))
        }
        Module::Npm(_) | Module::Node(_) => None,
        Module::External(module) => {
          // means it's Deno code importing an npm module
          let specifier =
            node::resolve_specifier_into_node_modules(&module.specifier);
          media_type = MediaType::from_specifier(&specifier);
          let file_path = specifier.to_file_path().unwrap();
          let code =
            std::fs::read_to_string(&file_path).with_context(|| {
              format!("Unable to load {}", file_path.display())
            })?;
          Some(Cow::Owned(code))
        }
      }
    } else if state
      .maybe_npm
      .as_ref()
      .map(|npm| npm.node_resolver.in_npm_package(specifier))
      .unwrap_or(false)
    {
      media_type = MediaType::from_specifier(specifier);
      let file_path = specifier.to_file_path().unwrap();
      let code = std::fs::read_to_string(&file_path)
        .with_context(|| format!("Unable to load {}", file_path.display()))?;
      Some(Cow::Owned(code))
    } else {
      None
    };
    hash = get_maybe_hash(maybe_source.as_deref(), state.hash_data);
    maybe_source
  };
  let Some(data) = data else {
    return Ok(None);
  };
  Ok(Some(LoadResponse {
    data: data.into_owned(),
    version: hash,
    script_kind: as_ts_script_kind(media_type),
  }))
}

#[derive(Debug, Deserialize, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct ResolveArgs {
  /// The base specifier that the supplied specifier strings should be resolved
  /// relative to.
  pub base: String,
  /// A list of specifiers that should be resolved.
  pub specifiers: Vec<String>,
}

#[op2]
#[serde]
fn op_resolve(
  state: &mut OpState,
  #[serde] args: ResolveArgs,
) -> Result<Vec<(String, String)>, AnyError> {
  op_resolve_inner(state, args)
}

#[inline]
fn op_resolve_inner(
  state: &mut OpState,
  args: ResolveArgs,
) -> Result<Vec<(String, String)>, AnyError> {
  let state = state.borrow_mut::<State>();
  let mut resolved: Vec<(String, String)> =
    Vec::with_capacity(args.specifiers.len());
  let referrer = if let Some(remapped_specifier) =
    state.remapped_specifiers.get(&args.base)
  {
    remapped_specifier.clone()
  } else if let Some(remapped_base) = state.root_map.get(&args.base) {
    remapped_base.clone()
  } else {
    normalize_specifier(&args.base, &state.current_dir).context(
      "Error converting a string module specifier for \"op_resolve\".",
    )?
  };
  for specifier in args.specifiers {
    if specifier.starts_with("node:") {
      resolved.push((
        MISSING_DEPENDENCY_SPECIFIER.to_string(),
        MediaType::Dts.to_string(),
      ));
      continue;
    }

    if specifier.starts_with("asset:///") {
      let media_type = MediaType::from_str(&specifier)
        .as_ts_extension()
        .to_string();
      resolved.push((specifier, media_type));
      continue;
    }

    let graph = &state.graph;
    let resolved_dep = graph
      .get(&referrer)
      .and_then(|m| m.js())
      .and_then(|m| m.dependencies_prefer_fast_check().get(&specifier))
      .and_then(|d| d.maybe_type.ok().or_else(|| d.maybe_code.ok()));

    let maybe_result = match resolved_dep {
      Some(ResolutionResolved { specifier, .. }) => {
        resolve_graph_specifier_types(specifier, &referrer, state)?
      }
      _ => resolve_non_graph_specifier_types(&specifier, &referrer, state)?,
    };
    let result = match maybe_result {
      Some((specifier, media_type)) => {
        let specifier_str = match specifier.scheme() {
          "data" | "blob" => {
            let specifier_str = hash_url(&specifier, media_type);
            state
              .remapped_specifiers
              .insert(specifier_str.clone(), specifier);
            specifier_str
          }
          _ => {
            if let Some(specifier_str) =
              maybe_remap_specifier(&specifier, media_type)
            {
              state
                .remapped_specifiers
                .insert(specifier_str.clone(), specifier);
              specifier_str
            } else {
              specifier.to_string()
            }
          }
        };
        (specifier_str, media_type.as_ts_extension().into())
      }
      None => (
        MISSING_DEPENDENCY_SPECIFIER.to_string(),
        ".d.ts".to_string(),
      ),
    };
    log::debug!("Resolved {} to {:?}", specifier, result);
    resolved.push(result);
  }

  Ok(resolved)
}

fn resolve_graph_specifier_types(
  specifier: &ModuleSpecifier,
  referrer: &ModuleSpecifier,
  state: &State,
) -> Result<Option<(ModuleSpecifier, MediaType)>, AnyError> {
  let graph = &state.graph;
  let maybe_module = graph.get(specifier);
  // follow the types reference directive, which may be pointing at an npm package
  let maybe_module = match maybe_module {
    Some(Module::Js(module)) => {
      let maybe_types_dep = module
        .maybe_types_dependency
        .as_ref()
        .map(|d| &d.dependency);
      match maybe_types_dep.and_then(|d| d.maybe_specifier()) {
        Some(specifier) => graph.get(specifier),
        _ => maybe_module,
      }
    }
    maybe_module => maybe_module,
  };

  // now get the types from the resolved module
  match maybe_module {
    Some(Module::Js(module)) => {
      Ok(Some((module.specifier.clone(), module.media_type)))
    }
    Some(Module::Json(module)) => {
      Ok(Some((module.specifier.clone(), module.media_type)))
    }
    Some(Module::Npm(module)) => {
      if let Some(npm) = &state.maybe_npm.as_ref() {
        let package_folder = npm
          .npm_resolver
          .as_managed()
          .unwrap() // should never be byonm because it won't create Module::Npm
          .resolve_pkg_folder_from_deno_module(module.nv_reference.nv())?;
        let maybe_resolution =
          npm.node_resolver.resolve_package_subpath_from_deno_module(
            &package_folder,
            module.nv_reference.sub_path(),
            referrer,
            NodeResolutionMode::Types,
            &PermissionsContainer::allow_all(),
          )?;
        Ok(Some(NodeResolution::into_specifier_and_media_type(
          maybe_resolution,
        )))
      } else {
        Ok(None)
      }
    }
    Some(Module::External(module)) => {
      // we currently only use "External" for when the module is in an npm package
      Ok(state.maybe_npm.as_ref().map(|npm| {
        let specifier =
          node::resolve_specifier_into_node_modules(&module.specifier);
        NodeResolution::into_specifier_and_media_type(
          npm.node_resolver.url_to_node_resolution(specifier).ok(),
        )
      }))
    }
    Some(Module::Node(_)) | None => Ok(None),
  }
}

fn resolve_non_graph_specifier_types(
  specifier: &str,
  referrer: &ModuleSpecifier,
  state: &State,
) -> Result<Option<(ModuleSpecifier, MediaType)>, AnyError> {
  let npm = match state.maybe_npm.as_ref() {
    Some(npm) => npm,
    None => return Ok(None), // we only support non-graph types for npm packages
  };
  let node_resolver = &npm.node_resolver;
  if node_resolver.in_npm_package(referrer) {
    // we're in an npm package, so use node resolution
    Ok(Some(NodeResolution::into_specifier_and_media_type(
      node_resolver
        .resolve(
          specifier,
          referrer,
          NodeResolutionMode::Types,
          &PermissionsContainer::allow_all(),
        )
        .ok()
        .flatten(),
    )))
  } else if let Ok(npm_req_ref) = NpmPackageReqReference::from_str(specifier) {
    // todo(dsherret): add support for injecting this in the graph so
    // we don't need this special code here.
    // This could occur when resolving npm:@types/node when it is
    // injected and not part of the graph
    let package_folder = npm
      .npm_resolver
      .resolve_pkg_folder_from_deno_module_req(npm_req_ref.req(), referrer)?;
    let maybe_resolution = node_resolver
      .resolve_package_subpath_from_deno_module(
        &package_folder,
        npm_req_ref.sub_path(),
        referrer,
        NodeResolutionMode::Types,
        &PermissionsContainer::allow_all(),
      )?;
    Ok(Some(NodeResolution::into_specifier_and_media_type(
      maybe_resolution,
    )))
  } else {
    Ok(None)
  }
}

#[op2(fast)]
fn op_is_node_file(state: &mut OpState, #[string] path: &str) -> bool {
  let state = state.borrow::<State>();
  match ModuleSpecifier::parse(path) {
    Ok(specifier) => state
      .maybe_npm
      .as_ref()
      .map(|n| n.node_resolver.in_npm_package(&specifier))
      .unwrap_or(false),
    Err(_) => false,
  }
}

#[derive(Debug, Deserialize, Eq, PartialEq)]
struct RespondArgs {
  pub diagnostics: Diagnostics,
  pub stats: Stats,
}

// TODO(bartlomieju): this mechanism is questionable.
// Can't we use something more efficient here?
#[op2]
fn op_respond(state: &mut OpState, #[serde] args: RespondArgs) {
  op_respond_inner(state, args)
}

#[inline]
fn op_respond_inner(state: &mut OpState, args: RespondArgs) {
  let state = state.borrow_mut::<State>();
  state.maybe_response = Some(args);
}

/// Execute a request on the supplied snapshot, returning a response which
/// contains information, like any emitted files, diagnostics, statistics and
/// optionally an updated TypeScript build info.
pub fn exec(request: Request) -> Result<Response, AnyError> {
  // tsc cannot handle root specifiers that don't have one of the "acceptable"
  // extensions.  Therefore, we have to check the root modules against their
  // extensions and remap any that are unacceptable to tsc and add them to the
  // op state so when requested, we can remap to the original specifier.
  let mut root_map = HashMap::new();
  let mut remapped_specifiers = HashMap::new();
  let root_names: Vec<String> = request
    .root_names
    .iter()
    .map(|(s, mt)| match s.scheme() {
      "data" | "blob" => {
        let specifier_str = hash_url(s, *mt);
        remapped_specifiers.insert(specifier_str.clone(), s.clone());
        specifier_str
      }
      _ => {
        if let Some(new_specifier) = mapped_specifier_for_tsc(s, *mt) {
          root_map.insert(new_specifier.clone(), s.clone());
          new_specifier
        } else {
          s.to_string()
        }
      }
    })
    .collect();

  deno_core::extension!(deno_cli_tsc,
    ops = [
      op_create_hash,
      op_emit,
      op_is_node_file,
      op_load,
      op_resolve,
      op_respond,
    ],
    options = {
      request: Request,
      root_map: HashMap<String, Url>,
      remapped_specifiers: HashMap<String, Url>,
    },
    state = |state, options| {
      state.put(State::new(
        options.request.graph,
        options.request.hash_data,
        options.request.maybe_npm,
        options.request.maybe_tsbuildinfo,
        options.root_map,
        options.remapped_specifiers,
        std::env::current_dir()
          .context("Unable to get CWD")
          .unwrap(),
      ));
    },
  );

  let request_value = json!({
    "config": request.config,
    "debug": request.debug,
    "rootNames": root_names,
    "localOnly": request.check_mode == TypeCheckMode::Local,
  });
  let exec_source = format!("globalThis.exec({request_value})");

  let mut runtime = JsRuntime::new(RuntimeOptions {
    startup_snapshot: Some(compiler_snapshot()),
    extensions: vec![deno_cli_tsc::init_ops(
      request,
      root_map,
      remapped_specifiers,
    )],
    ..Default::default()
  });

  runtime.execute_script(located_script_name!(), exec_source)?;

  let op_state = runtime.op_state();
  let mut op_state = op_state.borrow_mut();
  let state = op_state.take::<State>();

  if let Some(response) = state.maybe_response {
    let diagnostics = response.diagnostics;
    let maybe_tsbuildinfo = state.maybe_tsbuildinfo;
    let stats = response.stats;

    Ok(Response {
      diagnostics,
      maybe_tsbuildinfo,
      stats,
    })
  } else {
    Err(anyhow!("The response for the exec request was not set."))
  }
}

#[cfg(test)]
mod tests {
  use super::Diagnostic;
  use super::DiagnosticCategory;
  use super::*;
  use crate::args::TsConfig;
  use deno_core::futures::future;
  use deno_core::serde_json;
  use deno_core::OpState;
  use deno_graph::GraphKind;
  use deno_graph::ModuleGraph;
  use test_util::PathRef;

  #[derive(Debug, Default)]
  pub struct MockLoader {
    pub fixtures: PathRef,
  }

  impl deno_graph::source::Loader for MockLoader {
    fn load(
      &mut self,
      specifier: &ModuleSpecifier,
      _options: deno_graph::source::LoadOptions,
    ) -> deno_graph::source::LoadFuture {
      let specifier_text = specifier
        .to_string()
        .replace(":///", "_")
        .replace("://", "_")
        .replace('/', "-");
      let source_path = self.fixtures.join(specifier_text);
      let response = source_path.read_to_bytes_if_exists().map(|c| {
        Some(deno_graph::source::LoadResponse::Module {
          specifier: specifier.clone(),
          maybe_headers: None,
          content: c.into(),
        })
      });
      Box::pin(future::ready(response))
    }
  }

  async fn setup(
    maybe_specifier: Option<ModuleSpecifier>,
    maybe_hash_data: Option<u64>,
    maybe_tsbuildinfo: Option<String>,
  ) -> OpState {
    let specifier = maybe_specifier
      .unwrap_or_else(|| ModuleSpecifier::parse("file:///main.ts").unwrap());
    let hash_data = maybe_hash_data.unwrap_or(0);
    let fixtures = test_util::testdata_path().join("tsc2");
    let mut loader = MockLoader { fixtures };
    let mut graph = ModuleGraph::new(GraphKind::TypesOnly);
    graph
      .build(vec![specifier], &mut loader, Default::default())
      .await;
    let state = State::new(
      Arc::new(graph),
      hash_data,
      None,
      maybe_tsbuildinfo,
      HashMap::new(),
      HashMap::new(),
      std::env::current_dir()
        .context("Unable to get CWD")
        .unwrap(),
    );
    let mut op_state = OpState::new(None);
    op_state.put(state);
    op_state
  }

  async fn test_exec(
    specifier: &ModuleSpecifier,
  ) -> Result<Response, AnyError> {
    let hash_data = 123; // something random
    let fixtures = test_util::testdata_path().join("tsc2");
    let mut loader = MockLoader { fixtures };
    let mut graph = ModuleGraph::new(GraphKind::TypesOnly);
    graph
      .build(vec![specifier.clone()], &mut loader, Default::default())
      .await;
    let config = TsConfig::new(json!({
      "allowJs": true,
      "checkJs": false,
      "esModuleInterop": true,
      "emitDecoratorMetadata": false,
      "incremental": true,
      "jsx": "react",
      "jsxFactory": "React.createElement",
      "jsxFragmentFactory": "React.Fragment",
      "lib": ["deno.window"],
      "module": "esnext",
      "noEmit": true,
      "outDir": "internal:///",
      "strict": true,
      "target": "esnext",
      "tsBuildInfoFile": "internal:///.tsbuildinfo",
    }));
    let request = Request {
      config,
      debug: false,
      graph: Arc::new(graph),
      hash_data,
      maybe_npm: None,
      maybe_tsbuildinfo: None,
      root_names: vec![(specifier.clone(), MediaType::TypeScript)],
      check_mode: TypeCheckMode::All,
    };
    exec(request)
  }

  // TODO(bartlomieju): this test is segfaulting in V8, saying that there are too
  // few external references registered. It seems to be a bug in our snapshotting
  // logic. Because when we create TSC snapshot we register a few ops that
  // are called during snapshotting time, V8 expects at least as many references
  // when it starts up. The thing is that these ops are one-off - ie. they will never
  // be used again after the snapshot is taken. We should figure out a mechanism
  // to allow removing some of the ops before taking a snapshot.
  #[ignore]
  #[tokio::test]
  async fn test_compiler_snapshot() {
    let mut js_runtime = JsRuntime::new(RuntimeOptions {
      startup_snapshot: Some(compiler_snapshot()),
      ..Default::default()
    });
    js_runtime
      .execute_script(
        "<anon>",
        r#"
      if (!(globalThis.exec)) {
          throw Error("bad");
        }
        console.log(`ts version: ${ts.version}`);
      "#,
      )
      .unwrap();
  }

  #[tokio::test]
  async fn test_create_hash() {
    let mut state = setup(None, Some(123), None).await;
    let actual = op_create_hash_inner(&mut state, "some sort of content");
    assert_eq!(actual, "11905938177474799758");
  }

  #[tokio::test]
  async fn test_hash_url() {
    let specifier = deno_core::resolve_url(
      "data:application/javascript,console.log(\"Hello%20Deno\");",
    )
    .unwrap();
    assert_eq!(hash_url(&specifier, MediaType::JavaScript), "data:///d300ea0796bd72b08df10348e0b70514c021f2e45bfe59cec24e12e97cd79c58.js");
  }

  #[tokio::test]
  async fn test_emit_tsbuildinfo() {
    let mut state = setup(None, None, None).await;
    let actual = op_emit_inner(
      &mut state,
      EmitArgs {
        data: "some file content".to_string(),
        file_name: "internal:///.tsbuildinfo".to_string(),
      },
    );
    assert!(actual);
    let state = state.borrow::<State>();
    assert_eq!(
      state.maybe_tsbuildinfo,
      Some("some file content".to_string())
    );
  }

  #[tokio::test]
  async fn test_load() {
    let mut state = setup(
      Some(ModuleSpecifier::parse("https://deno.land/x/mod.ts").unwrap()),
      None,
      Some("some content".to_string()),
    )
    .await;
    let actual =
      op_load_inner(&mut state, "https://deno.land/x/mod.ts").unwrap();
    assert_eq!(
      serde_json::to_value(actual).unwrap(),
      json!({
        "data": "console.log(\"hello deno\");\n",
        "version": "7821807483407828376",
        "scriptKind": 3,
      })
    );
  }

  #[tokio::test]
  async fn test_load_asset() {
    let mut state = setup(
      Some(ModuleSpecifier::parse("https://deno.land/x/mod.ts").unwrap()),
      None,
      Some("some content".to_string()),
    )
    .await;
    let actual = op_load_inner(&mut state, "asset:///lib.dom.d.ts")
      .expect("should have invoked op")
      .expect("load should have succeeded");
    let expected = get_lazily_loaded_asset("lib.dom.d.ts").unwrap();
    assert_eq!(actual.data, expected);
    assert!(actual.version.is_some());
    assert_eq!(actual.script_kind, 3);
  }

  #[tokio::test]
  async fn test_load_tsbuildinfo() {
    let mut state = setup(
      Some(ModuleSpecifier::parse("https://deno.land/x/mod.ts").unwrap()),
      None,
      Some("some content".to_string()),
    )
    .await;
    let actual = op_load_inner(&mut state, "internal:///.tsbuildinfo")
      .expect("should have invoked op")
      .expect("load should have succeeded");
    assert_eq!(
      serde_json::to_value(actual).unwrap(),
      json!({
        "data": "some content",
        "version": null,
        "scriptKind": 0,
      })
    );
  }

  #[tokio::test]
  async fn test_load_missing_specifier() {
    let mut state = setup(None, None, None).await;
    let actual = op_load_inner(&mut state, "https://deno.land/x/mod.ts")
      .expect("should have invoked op");
    assert_eq!(serde_json::to_value(actual).unwrap(), json!(null));
  }

  #[tokio::test]
  async fn test_resolve() {
    let mut state = setup(
      Some(ModuleSpecifier::parse("https://deno.land/x/a.ts").unwrap()),
      None,
      None,
    )
    .await;
    let actual = op_resolve_inner(
      &mut state,
      ResolveArgs {
        base: "https://deno.land/x/a.ts".to_string(),
        specifiers: vec!["./b.ts".to_string()],
      },
    )
    .expect("should have invoked op");
    assert_eq!(
      actual,
      vec![("https://deno.land/x/b.ts".into(), ".ts".into())]
    );
  }

  #[tokio::test]
  async fn test_resolve_empty() {
    let mut state = setup(
      Some(ModuleSpecifier::parse("https://deno.land/x/a.ts").unwrap()),
      None,
      None,
    )
    .await;
    let actual = op_resolve_inner(
      &mut state,
      ResolveArgs {
        base: "https://deno.land/x/a.ts".to_string(),
        specifiers: vec!["./bad.ts".to_string()],
      },
    )
    .expect("should have not errored");
    assert_eq!(
      actual,
      vec![(MISSING_DEPENDENCY_SPECIFIER.into(), ".d.ts".into())]
    );
  }

  #[tokio::test]
  async fn test_respond() {
    let mut state = setup(None, None, None).await;
    let args = serde_json::from_value(json!({
      "diagnostics": [
        {
          "messageText": "Unknown compiler option 'invalid'.",
          "category": 1,
          "code": 5023
        }
      ],
      "stats": [["a", 12]]
    }))
    .unwrap();
    op_respond_inner(&mut state, args);
    let state = state.borrow::<State>();
    assert_eq!(
      state.maybe_response,
      Some(RespondArgs {
        diagnostics: Diagnostics::new(vec![Diagnostic {
          category: DiagnosticCategory::Error,
          code: 5023,
          start: None,
          end: None,
          original_source_start: None,
          message_text: Some(
            "Unknown compiler option \'invalid\'.".to_string()
          ),
          message_chain: None,
          source: None,
          source_line: None,
          file_name: None,
          related_information: None,
        }]),
        stats: Stats(vec![("a".to_string(), 12)])
      })
    );
  }

  #[tokio::test]
  async fn test_exec_basic() {
    let specifier = ModuleSpecifier::parse("https://deno.land/x/a.ts").unwrap();
    let actual = test_exec(&specifier)
      .await
      .expect("exec should not have errored");
    assert!(actual.diagnostics.is_empty());
    assert!(actual.maybe_tsbuildinfo.is_some());
    assert_eq!(actual.stats.0.len(), 12);
  }

  #[tokio::test]
  async fn test_exec_reexport_dts() {
    let specifier = ModuleSpecifier::parse("file:///reexports.ts").unwrap();
    let actual = test_exec(&specifier)
      .await
      .expect("exec should not have errored");
    assert!(actual.diagnostics.is_empty());
    assert!(actual.maybe_tsbuildinfo.is_some());
    assert_eq!(actual.stats.0.len(), 12);
  }

  #[tokio::test]
  async fn fix_lib_ref() {
    let specifier = ModuleSpecifier::parse("file:///libref.ts").unwrap();
    let actual = test_exec(&specifier)
      .await
      .expect("exec should not have errored");
    assert!(actual.diagnostics.is_empty());
  }
}