// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.

use crate::deno_dir::DenoDir;
use crate::disk_cache::DiskCache;
use crate::file_fetcher::SourceFileFetcher;
use crate::media_type::MediaType;
use crate::permissions::Permissions;
use crate::program_state::ProgramState;

use deno_core::error::AnyError;
use deno_core::futures::Future;
use deno_core::futures::FutureExt;
use deno_core::serde_json;
use deno_core::ModuleSpecifier;
use serde::Deserialize;
use serde::Serialize;
use std::collections::HashMap;
use std::env;
use std::fmt;
use std::path::PathBuf;
use std::pin::Pin;
use std::sync::Arc;

pub type DependencyMap = HashMap<String, Dependency>;
pub type FetchFuture =
  Pin<Box<(dyn Future<Output = Result<CachedModule, AnyError>> + 'static)>>;

#[derive(Debug, Clone)]
pub struct CachedModule {
  pub maybe_dependencies: Option<DependencyMap>,
  pub maybe_emit: Option<Emit>,
  pub maybe_emit_path: Option<(PathBuf, Option<PathBuf>)>,
  pub maybe_types: Option<String>,
  pub maybe_version: Option<String>,
  pub media_type: MediaType,
  pub requested_specifier: ModuleSpecifier,
  pub source: String,
  pub source_path: PathBuf,
  pub specifier: ModuleSpecifier,
}

#[cfg(test)]
impl Default for CachedModule {
  fn default() -> Self {
    let specifier = ModuleSpecifier::resolve_url("file:///example.js").unwrap();
    CachedModule {
      maybe_dependencies: None,
      maybe_emit: None,
      maybe_emit_path: None,
      maybe_types: None,
      maybe_version: None,
      media_type: MediaType::Unknown,
      requested_specifier: specifier.clone(),
      source: "".to_string(),
      source_path: PathBuf::new(),
      specifier,
    }
  }
}

/// An enum to own the a specific emit.
///
/// Currently there is only one type of emit that is cacheable, but this has
/// been added to future proof the ability for the specifier handler
/// implementations to be able to handle other types of emits, like form a
/// runtime API which might have a different configuration.
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub enum Emit {
  /// Code that was emitted for use by the CLI
  Cli((String, Option<String>)),
}

impl Default for Emit {
  fn default() -> Self {
    Emit::Cli(("".to_string(), None))
  }
}

#[derive(Debug, Clone, Default)]
pub struct Dependency {
  /// The module specifier that resolves to the runtime code dependency for the
  /// module.
  pub maybe_code: Option<ModuleSpecifier>,
  /// The module specifier that resolves to the type only dependency for the
  /// module.
  pub maybe_type: Option<ModuleSpecifier>,
}

pub trait SpecifierHandler {
  /// Instructs the handler to fetch a specifier or retrieve its value from the
  /// cache.
  fn fetch(&mut self, specifier: ModuleSpecifier) -> FetchFuture;

  /// Get the optional build info from the cache for a given module specifier.
  /// Because build infos are only associated with the "root" modules, they are
  /// not expected to be cached for each module, but are "lazily" checked when
  /// a root module is identified.  The `emit_type` also indicates what form
  /// of the module the build info is valid for.
  fn get_ts_build_info(
    &self,
    specifier: &ModuleSpecifier,
  ) -> Result<Option<String>, AnyError>;

  /// Set the emit for the module specifier.
  fn set_cache(
    &mut self,
    specifier: &ModuleSpecifier,
    emit: &Emit,
  ) -> Result<(), AnyError>;

  /// When parsed out of a JavaScript module source, the triple slash reference
  /// to the types should be stored in the cache.
  fn set_types(
    &mut self,
    specifier: &ModuleSpecifier,
    types: String,
  ) -> Result<(), AnyError>;

  /// Set the build info for a module specifier, also providing the cache type.
  fn set_ts_build_info(
    &mut self,
    specifier: &ModuleSpecifier,
    ts_build_info: String,
  ) -> Result<(), AnyError>;

  /// Set the graph dependencies for a given module specifier.
  fn set_deps(
    &mut self,
    specifier: &ModuleSpecifier,
    dependencies: DependencyMap,
  ) -> Result<(), AnyError>;

  /// Set the version of the source for a given module, which is used to help
  /// determine if a module needs to be re-emitted.
  fn set_version(
    &mut self,
    specifier: &ModuleSpecifier,
    version: String,
  ) -> Result<(), AnyError>;
}

impl fmt::Debug for dyn SpecifierHandler {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    write!(f, "SpecifierHandler {{ }}")
  }
}

/// A representation of meta data for a compiled file.
///
/// *Note* this is currently just a copy of what is located in `tsc.rs` but will
/// be refactored to be able to store dependencies and type information in the
/// future.
#[derive(Deserialize, Serialize)]
pub struct CompiledFileMetadata {
  pub version_hash: String,
}

impl CompiledFileMetadata {
  pub fn from_bytes(bytes: &[u8]) -> Result<Self, AnyError> {
    let metadata_string = std::str::from_utf8(bytes)?;
    serde_json::from_str::<Self>(metadata_string).map_err(|e| e.into())
  }

  pub fn to_json_string(&self) -> Result<String, AnyError> {
    serde_json::to_string(self).map_err(|e| e.into())
  }
}

/// An implementation of the `SpecifierHandler` trait that integrates with the
/// existing `file_fetcher` interface, which will eventually be refactored to
/// align it more to the `SpecifierHandler` trait.
pub struct FetchHandler {
  disk_cache: DiskCache,
  file_fetcher: SourceFileFetcher,
  permissions: Permissions,
}

impl FetchHandler {
  pub fn new(
    program_state: &Arc<ProgramState>,
    permissions: Permissions,
  ) -> Result<Self, AnyError> {
    let custom_root = env::var("DENO_DIR").map(String::into).ok();
    let deno_dir = DenoDir::new(custom_root)?;
    let disk_cache = deno_dir.gen_cache;
    let file_fetcher = program_state.file_fetcher.clone();

    Ok(FetchHandler {
      disk_cache,
      file_fetcher,
      permissions,
    })
  }
}

impl SpecifierHandler for FetchHandler {
  fn fetch(&mut self, requested_specifier: ModuleSpecifier) -> FetchFuture {
    let permissions = self.permissions.clone();
    let file_fetcher = self.file_fetcher.clone();
    let disk_cache = self.disk_cache.clone();

    async move {
      let source_file = file_fetcher
        .fetch_source_file(&requested_specifier, None, permissions)
        .await?;
      let url = source_file.url.clone();
      let filename = disk_cache.get_cache_filename_with_extension(&url, "meta");
      let maybe_version = if let Ok(bytes) = disk_cache.get(&filename) {
        if let Ok(compiled_file_metadata) =
          CompiledFileMetadata::from_bytes(&bytes)
        {
          Some(compiled_file_metadata.version_hash)
        } else {
          None
        }
      } else {
        None
      };

      let mut maybe_map_path = None;
      let map_path =
        disk_cache.get_cache_filename_with_extension(&url, "js.map");
      let maybe_map = if let Ok(map) = disk_cache.get(&map_path) {
        maybe_map_path = Some(disk_cache.location.join(map_path));
        Some(String::from_utf8(map)?)
      } else {
        None
      };
      let mut maybe_emit = None;
      let mut maybe_emit_path = None;
      let emit_path = disk_cache.get_cache_filename_with_extension(&url, "js");
      if let Ok(code) = disk_cache.get(&emit_path) {
        maybe_emit = Some(Emit::Cli((String::from_utf8(code)?, maybe_map)));
        maybe_emit_path =
          Some((disk_cache.location.join(emit_path), maybe_map_path));
      };
      let specifier = ModuleSpecifier::from(url);

      Ok(CachedModule {
        maybe_dependencies: None,
        maybe_emit,
        maybe_emit_path,
        maybe_types: source_file.types_header,
        maybe_version,
        media_type: source_file.media_type,
        requested_specifier,
        source: source_file.source_code,
        source_path: source_file.filename,
        specifier,
      })
    }
    .boxed_local()
  }

  fn get_ts_build_info(
    &self,
    specifier: &ModuleSpecifier,
  ) -> Result<Option<String>, AnyError> {
    let filename = self
      .disk_cache
      .get_cache_filename_with_extension(specifier.as_url(), "buildinfo");
    if let Ok(ts_build_info) = self.disk_cache.get(&filename) {
      return Ok(Some(String::from_utf8(ts_build_info)?));
    }

    Ok(None)
  }

  fn set_ts_build_info(
    &mut self,
    specifier: &ModuleSpecifier,
    ts_build_info: String,
  ) -> Result<(), AnyError> {
    let filename = self
      .disk_cache
      .get_cache_filename_with_extension(specifier.as_url(), "buildinfo");
    self
      .disk_cache
      .set(&filename, ts_build_info.as_bytes())
      .map_err(|e| e.into())
  }

  fn set_cache(
    &mut self,
    specifier: &ModuleSpecifier,
    emit: &Emit,
  ) -> Result<(), AnyError> {
    match emit {
      Emit::Cli((code, maybe_map)) => {
        let url = specifier.as_url();
        let filename =
          self.disk_cache.get_cache_filename_with_extension(url, "js");
        self.disk_cache.set(&filename, code.as_bytes())?;

        if let Some(map) = maybe_map {
          let filename = self
            .disk_cache
            .get_cache_filename_with_extension(url, "js.map");
          self.disk_cache.set(&filename, map.as_bytes())?;
        }
      }
    };

    Ok(())
  }

  fn set_deps(
    &mut self,
    _specifier: &ModuleSpecifier,
    _dependencies: DependencyMap,
  ) -> Result<(), AnyError> {
    // file_fetcher doesn't have the concept of caching dependencies
    Ok(())
  }

  fn set_types(
    &mut self,
    _specifier: &ModuleSpecifier,
    _types: String,
  ) -> Result<(), AnyError> {
    // file_fetcher doesn't have the concept of caching of the types
    Ok(())
  }

  fn set_version(
    &mut self,
    specifier: &ModuleSpecifier,
    version_hash: String,
  ) -> Result<(), AnyError> {
    let compiled_file_metadata = CompiledFileMetadata { version_hash };
    let filename = self
      .disk_cache
      .get_cache_filename_with_extension(specifier.as_url(), "meta");

    self
      .disk_cache
      .set(
        &filename,
        compiled_file_metadata.to_json_string()?.as_bytes(),
      )
      .map_err(|e| e.into())
  }
}

#[cfg(test)]
pub mod tests {
  use super::*;
  use crate::http_cache::HttpCache;
  use tempfile::TempDir;

  fn setup() -> (TempDir, FetchHandler) {
    let temp_dir = TempDir::new().expect("could not setup");
    let deno_dir = DenoDir::new(Some(temp_dir.path().to_path_buf()))
      .expect("could not setup");

    let file_fetcher = SourceFileFetcher::new(
      HttpCache::new(&temp_dir.path().to_path_buf().join("deps")),
      true,
      Vec::new(),
      false,
      false,
      None,
    )
    .expect("could not setup");
    let disk_cache = deno_dir.gen_cache;

    let fetch_handler = FetchHandler {
      disk_cache,
      file_fetcher,
      permissions: Permissions::allow_all(),
    };

    (temp_dir, fetch_handler)
  }

  #[tokio::test]
  async fn test_fetch_handler_fetch() {
    let _http_server_guard = test_util::http_server();
    let (_, mut file_fetcher) = setup();
    let specifier = ModuleSpecifier::resolve_url_or_path(
      "http://localhost:4545/cli/tests/subdir/mod2.ts",
    )
    .unwrap();
    let cached_module: CachedModule =
      file_fetcher.fetch(specifier.clone()).await.unwrap();
    assert!(cached_module.maybe_emit.is_none());
    assert!(cached_module.maybe_dependencies.is_none());
    assert_eq!(cached_module.media_type, MediaType::TypeScript);
    assert_eq!(
      cached_module.source,
      "export { printHello } from \"./print_hello.ts\";\n"
    );
    assert_eq!(cached_module.specifier, specifier);
  }

  #[tokio::test]
  async fn test_fetch_handler_set_cache() {
    let _http_server_guard = test_util::http_server();
    let (_, mut file_fetcher) = setup();
    let specifier = ModuleSpecifier::resolve_url_or_path(
      "http://localhost:4545/cli/tests/subdir/mod2.ts",
    )
    .unwrap();
    let cached_module: CachedModule =
      file_fetcher.fetch(specifier.clone()).await.unwrap();
    assert!(cached_module.maybe_emit.is_none());
    let code = String::from("some code");
    file_fetcher
      .set_cache(&specifier, &Emit::Cli((code, None)))
      .expect("could not set cache");
    let cached_module: CachedModule =
      file_fetcher.fetch(specifier.clone()).await.unwrap();
    assert_eq!(
      cached_module.maybe_emit,
      Some(Emit::Cli(("some code".to_string(), None)))
    );
  }
}