// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.

use super::analysis;
use super::language_server;
use super::tsc;

use crate::diagnostics;
use crate::media_type::MediaType;
use crate::tokio_util::create_basic_runtime;

use deno_core::error::anyhow;
use deno_core::error::AnyError;
use deno_core::resolve_url;
use deno_core::ModuleSpecifier;
use log::error;
use lspower::lsp;
use std::collections::HashMap;
use std::collections::HashSet;
use std::mem;
use std::sync::Arc;
use std::thread;
use tokio::sync::mpsc;
use tokio::sync::Mutex;
use tokio::time::sleep;
use tokio::time::Duration;
use tokio::time::Instant;

pub type DiagnosticRecord =
  (ModuleSpecifier, Option<i32>, Vec<lsp::Diagnostic>);
pub type DiagnosticVec = Vec<DiagnosticRecord>;
type TsDiagnosticsMap = HashMap<String, Vec<diagnostics::Diagnostic>>;

#[derive(Debug, Hash, Clone, PartialEq, Eq)]
pub(crate) enum DiagnosticSource {
  Deno,
  DenoLint,
  TypeScript,
}

#[derive(Debug, Default)]
struct DiagnosticCollection {
  map: HashMap<(ModuleSpecifier, DiagnosticSource), Vec<lsp::Diagnostic>>,
  versions: HashMap<ModuleSpecifier, HashMap<DiagnosticSource, i32>>,
  changes: HashSet<ModuleSpecifier>,
}

impl DiagnosticCollection {
  pub fn get(
    &self,
    specifier: &ModuleSpecifier,
    source: DiagnosticSource,
  ) -> impl Iterator<Item = &lsp::Diagnostic> {
    self
      .map
      .get(&(specifier.clone(), source))
      .into_iter()
      .flatten()
  }

  pub fn get_version(
    &self,
    specifier: &ModuleSpecifier,
    source: &DiagnosticSource,
  ) -> Option<i32> {
    let source_version = self.versions.get(specifier)?;
    source_version.get(source).cloned()
  }

  pub fn set(&mut self, source: DiagnosticSource, record: DiagnosticRecord) {
    let (specifier, maybe_version, diagnostics) = record;
    self
      .map
      .insert((specifier.clone(), source.clone()), diagnostics);
    if let Some(version) = maybe_version {
      let source_version = self.versions.entry(specifier.clone()).or_default();
      source_version.insert(source, version);
    }
    self.changes.insert(specifier);
  }

  pub fn take_changes(&mut self) -> Option<HashSet<ModuleSpecifier>> {
    if self.changes.is_empty() {
      None
    } else {
      Some(mem::take(&mut self.changes))
    }
  }
}

#[derive(Debug)]
pub(crate) struct DiagnosticsServer {
  channel: Option<mpsc::UnboundedSender<()>>,
  collection: Arc<Mutex<DiagnosticCollection>>,
}

impl DiagnosticsServer {
  pub(crate) fn new() -> Self {
    let collection = Arc::new(Mutex::new(DiagnosticCollection::default()));
    Self {
      channel: None,
      collection,
    }
  }

  pub(crate) async fn get(
    &self,
    specifier: &ModuleSpecifier,
    source: DiagnosticSource,
  ) -> Vec<lsp::Diagnostic> {
    self
      .collection
      .lock()
      .await
      .get(specifier, source)
      .cloned()
      .collect()
  }

  pub(crate) async fn invalidate(&self, specifier: &ModuleSpecifier) {
    self.collection.lock().await.versions.remove(specifier);
  }

  pub(crate) fn start(
    &mut self,
    language_server: Arc<Mutex<language_server::Inner>>,
    client: lspower::Client,
    ts_server: Arc<tsc::TsServer>,
  ) {
    let (tx, mut rx) = mpsc::unbounded_channel::<()>();
    self.channel = Some(tx);
    let collection = self.collection.clone();

    let _join_handle = thread::spawn(move || {
      let runtime = create_basic_runtime();

      runtime.block_on(async {
        // Debounce timer delay. 150ms between keystrokes is about 45 WPM, so we
        // want something that is longer than that, but not too long to
        // introduce detectable UI delay; 200ms is a decent compromise.
        const DELAY: Duration = Duration::from_millis(200);
        // If the debounce timer isn't active, it will be set to expire "never",
        // which is actually just 1 year in the future.
        const NEVER: Duration = Duration::from_secs(365 * 24 * 60 * 60);

        // A flag that is set whenever something has changed that requires the
        // diagnostics collection to be updated.
        let mut dirty = false;

        let debounce_timer = sleep(NEVER);
        tokio::pin!(debounce_timer);

        loop {
          // "race" the next message off the rx queue or the debounce timer.
          // The debounce timer gets reset every time a message comes off the
          // queue. When the debounce timer expires, a snapshot of the most
          // up-to-date state is used to produce diagnostics.
          tokio::select! {
            maybe_request = rx.recv() => {
              match maybe_request {
                // channel has closed
                None => break,
                Some(_) => {
                  dirty = true;
                  debounce_timer.as_mut().reset(Instant::now() + DELAY);
                }
              }
            }
            _ = debounce_timer.as_mut(), if dirty => {
              dirty = false;
              debounce_timer.as_mut().reset(Instant::now() + NEVER);

              let snapshot = language_server.lock().await.snapshot();
              update_diagnostics(
                &client,
                collection.clone(),
                &snapshot,
                &ts_server
              ).await;
            }
          }
        }
      })
    });
  }

  pub(crate) fn update(&self) -> Result<(), AnyError> {
    if let Some(tx) = &self.channel {
      tx.send(()).map_err(|err| err.into())
    } else {
      Err(anyhow!("diagnostics server not started"))
    }
  }
}

impl<'a> From<&'a diagnostics::DiagnosticCategory> for lsp::DiagnosticSeverity {
  fn from(category: &'a diagnostics::DiagnosticCategory) -> Self {
    match category {
      diagnostics::DiagnosticCategory::Error => lsp::DiagnosticSeverity::Error,
      diagnostics::DiagnosticCategory::Warning => {
        lsp::DiagnosticSeverity::Warning
      }
      diagnostics::DiagnosticCategory::Suggestion => {
        lsp::DiagnosticSeverity::Hint
      }
      diagnostics::DiagnosticCategory::Message => {
        lsp::DiagnosticSeverity::Information
      }
    }
  }
}

impl<'a> From<&'a diagnostics::Position> for lsp::Position {
  fn from(pos: &'a diagnostics::Position) -> Self {
    Self {
      line: pos.line as u32,
      character: pos.character as u32,
    }
  }
}

fn get_diagnostic_message(diagnostic: &diagnostics::Diagnostic) -> String {
  if let Some(message) = diagnostic.message_text.clone() {
    message
  } else if let Some(message_chain) = diagnostic.message_chain.clone() {
    message_chain.format_message(0)
  } else {
    "[missing message]".to_string()
  }
}

fn to_lsp_range(
  start: &diagnostics::Position,
  end: &diagnostics::Position,
) -> lsp::Range {
  lsp::Range {
    start: start.into(),
    end: end.into(),
  }
}

fn to_lsp_related_information(
  related_information: &Option<Vec<diagnostics::Diagnostic>>,
) -> Option<Vec<lsp::DiagnosticRelatedInformation>> {
  related_information.as_ref().map(|related| {
    related
      .iter()
      .filter_map(|ri| {
        if let (Some(source), Some(start), Some(end)) =
          (&ri.source, &ri.start, &ri.end)
        {
          let uri = lsp::Url::parse(&source).unwrap();
          Some(lsp::DiagnosticRelatedInformation {
            location: lsp::Location {
              uri,
              range: to_lsp_range(start, end),
            },
            message: get_diagnostic_message(&ri),
          })
        } else {
          None
        }
      })
      .collect()
  })
}

fn ts_json_to_diagnostics(
  diagnostics: Vec<diagnostics::Diagnostic>,
) -> Vec<lsp::Diagnostic> {
  diagnostics
    .iter()
    .filter_map(|d| {
      if let (Some(start), Some(end)) = (&d.start, &d.end) {
        Some(lsp::Diagnostic {
          range: to_lsp_range(start, end),
          severity: Some((&d.category).into()),
          code: Some(lsp::NumberOrString::Number(d.code as i32)),
          code_description: None,
          source: Some("deno-ts".to_string()),
          message: get_diagnostic_message(d),
          related_information: to_lsp_related_information(
            &d.related_information,
          ),
          tags: match d.code {
            // These are codes that indicate the variable is unused.
            2695 | 6133 | 6138 | 6192 | 6196 | 6198 | 6199 | 7027 | 7028 => {
              Some(vec![lsp::DiagnosticTag::Unnecessary])
            }
            _ => None,
          },
          data: None,
        })
      } else {
        None
      }
    })
    .collect()
}

async fn generate_lint_diagnostics(
  snapshot: &language_server::StateSnapshot,
  collection: Arc<Mutex<DiagnosticCollection>>,
) -> Result<DiagnosticVec, AnyError> {
  let documents = snapshot.documents.clone();
  let workspace_settings = snapshot.config.workspace_settings.clone();
  tokio::task::spawn(async move {
    let mut diagnostics_vec = Vec::new();
    if workspace_settings.lint {
      for specifier in documents.open_specifiers() {
        let version = documents.version(specifier);
        let current_version = collection
          .lock()
          .await
          .get_version(specifier, &DiagnosticSource::DenoLint);
        if version != current_version {
          let media_type = MediaType::from(specifier);
          if let Ok(Some(source_code)) = documents.content(specifier) {
            if let Ok(references) = analysis::get_lint_references(
              specifier,
              &media_type,
              &source_code,
            ) {
              let diagnostics =
                references.into_iter().map(|r| r.to_diagnostic()).collect();
              diagnostics_vec.push((specifier.clone(), version, diagnostics));
            } else {
              diagnostics_vec.push((specifier.clone(), version, Vec::new()));
            }
          } else {
            error!("Missing file contents for: {}", specifier);
          }
        }
      }
    }
    Ok(diagnostics_vec)
  })
  .await
  .unwrap()
}

async fn generate_ts_diagnostics(
  snapshot: &language_server::StateSnapshot,
  collection: Arc<Mutex<DiagnosticCollection>>,
  ts_server: &tsc::TsServer,
) -> Result<DiagnosticVec, AnyError> {
  let mut diagnostics_vec = Vec::new();
  let specifiers: Vec<ModuleSpecifier> = {
    let collection = collection.lock().await;
    snapshot
      .documents
      .open_specifiers()
      .iter()
      .filter_map(|&s| {
        let version = snapshot.documents.version(s);
        let current_version =
          collection.get_version(s, &DiagnosticSource::TypeScript);
        if version == current_version {
          None
        } else {
          Some(s.clone())
        }
      })
      .collect()
  };
  if !specifiers.is_empty() {
    let req = tsc::RequestMethod::GetDiagnostics(specifiers);
    let ts_diagnostics_map: TsDiagnosticsMap =
      ts_server.request(snapshot.clone(), req).await?;
    for (specifier_str, ts_diagnostics) in ts_diagnostics_map {
      let specifier = resolve_url(&specifier_str)?;
      let version = snapshot.documents.version(&specifier);
      diagnostics_vec.push((
        specifier,
        version,
        ts_json_to_diagnostics(ts_diagnostics),
      ));
    }
  }
  Ok(diagnostics_vec)
}

/// Generate diagnostics for dependencies of a module, attempting to resolve
/// dependencies on the local file system or in the DENO_DIR cache.
async fn generate_deps_diagnostics(
  snapshot: &language_server::StateSnapshot,
  collection: Arc<Mutex<DiagnosticCollection>>,
) -> Result<DiagnosticVec, AnyError> {
  let config = snapshot.config.clone();
  let documents = snapshot.documents.clone();
  let sources = snapshot.sources.clone();
  tokio::task::spawn(async move {
    let mut diagnostics_vec = Vec::new();

    for specifier in documents.open_specifiers() {
      if !config.specifier_enabled(specifier) {
        continue;
      }
      let version = documents.version(specifier);
      let current_version = collection
        .lock()
        .await
        .get_version(specifier, &DiagnosticSource::Deno);
      if version != current_version {
        let mut diagnostics = Vec::new();
        if let Some(dependencies) = documents.dependencies(specifier) {
          for (_, dependency) in dependencies {
            // TODO(@kitsonk) add diagnostics for maybe_type dependencies
            if let (Some(code), Some(range)) =
              (dependency.maybe_code, dependency.maybe_code_specifier_range)
            {
              match code {
                analysis::ResolvedDependency::Err(err) => diagnostics.push(lsp::Diagnostic {
                  range,
                  severity: Some(lsp::DiagnosticSeverity::Error),
                  code: Some(err.as_code()),
                  code_description: None,
                  source: Some("deno".to_string()),
                  message: err.to_string(),
                  related_information: None,
                  tags: None,
                  data: None,
                }),
                analysis::ResolvedDependency::Resolved(specifier) => {
                  if !(documents.contains_key(&specifier) || sources.contains_key(&specifier)) {
                    let (code, message) = match specifier.scheme() {
                      "file" => (Some(lsp::NumberOrString::String("no-local".to_string())), format!("Unable to load a local module: \"{}\".\n  Please check the file path.", specifier)),
                      "data" => (Some(lsp::NumberOrString::String("no-cache-data".to_string())), "Uncached data URL.".to_string()),
                      "blob" => (Some(lsp::NumberOrString::String("no-cache-blob".to_string())), "Uncached blob URL.".to_string()),
                      _ => (Some(lsp::NumberOrString::String("no-cache".to_string())), format!("Uncached or missing remote URL: \"{}\".", specifier)),
                    };
                    diagnostics.push(lsp::Diagnostic {
                      range,
                      severity: Some(lsp::DiagnosticSeverity::Error),
                      code,
                      code_description: None,
                      source: Some("deno".to_string()),
                      message,
                      related_information: None,
                      tags: None,
                      data: None,
                    });
                  }
                },
              }
            }
          }
        }
        diagnostics_vec.push((specifier.clone(), version, diagnostics));
      }
    }

    Ok(diagnostics_vec)
  })
  .await
  .unwrap()
}

/// Publishes diagnostics to the client.
async fn publish_diagnostics(
  client: &lspower::Client,
  collection: Arc<Mutex<DiagnosticCollection>>,
  snapshot: &language_server::StateSnapshot,
) {
  let mut collection = collection.lock().await;
  if let Some(changes) = collection.take_changes() {
    for specifier in changes {
      let mut diagnostics: Vec<lsp::Diagnostic> =
        if snapshot.config.workspace_settings.lint {
          collection
            .get(&specifier, DiagnosticSource::DenoLint)
            .cloned()
            .collect()
        } else {
          Vec::new()
        };
      if snapshot.config.specifier_enabled(&specifier) {
        diagnostics.extend(
          collection
            .get(&specifier, DiagnosticSource::TypeScript)
            .cloned(),
        );
        diagnostics
          .extend(collection.get(&specifier, DiagnosticSource::Deno).cloned());
      }
      let uri = specifier.clone();
      let version = snapshot.documents.version(&specifier);
      client.publish_diagnostics(uri, diagnostics, version).await;
    }
  }
}

/// Updates diagnostics for any specifiers that don't have the correct version
/// generated and publishes the diagnostics to the client.
async fn update_diagnostics(
  client: &lspower::Client,
  collection: Arc<Mutex<DiagnosticCollection>>,
  snapshot: &language_server::StateSnapshot,
  ts_server: &tsc::TsServer,
) {
  let mark = snapshot.performance.mark("update_diagnostics", None::<()>);

  let lint = async {
    let mark = snapshot
      .performance
      .mark("update_diagnostics_lint", None::<()>);
    let collection = collection.clone();
    let diagnostics = generate_lint_diagnostics(snapshot, collection.clone())
      .await
      .map_err(|err| {
        error!("Error generating lint diagnostics: {}", err);
      })
      .unwrap_or_default();
    {
      let mut collection = collection.lock().await;
      for diagnostic_record in diagnostics {
        collection.set(DiagnosticSource::DenoLint, diagnostic_record);
      }
    }
    publish_diagnostics(client, collection, snapshot).await;
    snapshot.performance.measure(mark);
  };

  let ts = async {
    let mark = snapshot
      .performance
      .mark("update_diagnostics_ts", None::<()>);
    let collection = collection.clone();
    let diagnostics =
      generate_ts_diagnostics(snapshot, collection.clone(), ts_server)
        .await
        .map_err(|err| {
          error!("Error generating TypeScript diagnostics: {}", err);
        })
        .unwrap_or_default();
    {
      let mut collection = collection.lock().await;
      for diagnostic_record in diagnostics {
        collection.set(DiagnosticSource::TypeScript, diagnostic_record);
      }
    }
    publish_diagnostics(client, collection, snapshot).await;
    snapshot.performance.measure(mark);
  };

  let deps = async {
    let mark = snapshot
      .performance
      .mark("update_diagnostics_deps", None::<()>);
    let collection = collection.clone();
    let diagnostics = generate_deps_diagnostics(snapshot, collection.clone())
      .await
      .map_err(|err| {
        error!("Error generating Deno diagnostics: {}", err);
      })
      .unwrap_or_default();
    {
      let mut collection = collection.lock().await;
      for diagnostic_record in diagnostics {
        collection.set(DiagnosticSource::Deno, diagnostic_record);
      }
    }
    publish_diagnostics(client, collection, snapshot).await;
    snapshot.performance.measure(mark);
  };

  tokio::join!(lint, ts, deps);
  snapshot.performance.measure(mark);
}