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

use deno_core::error::generic_error;
use deno_core::error::AnyError;
use deno_core::serde::de;
use deno_core::serde::Deserialize;
use deno_core::serde::Serialize;
use deno_core::serde_json;
use deno_core::serde_json::json;
use deno_core::serde_json::Value;
use lazy_static::lazy_static;
use regex::Regex;
use std::collections::HashMap;
use std::io::BufRead;
use std::io::Read;
use std::io::Write;
use std::path::Path;
use std::process::ChildStdin;
use std::process::ChildStdout;
use std::process::Command;
use std::process::Stdio;
use std::time::Duration;
use std::time::Instant;

static FIXTURE_DB_TS: &str = include_str!("fixtures/db.ts");
static FIXTURE_DB_MESSAGES: &[u8] = include_bytes!("fixtures/db_messages.json");
static FIXTURE_INIT_JSON: &[u8] =
  include_bytes!("fixtures/initialize_params.json");

lazy_static! {
  static ref CONTENT_TYPE_REG: Regex =
    Regex::new(r"(?i)^content-length:\s+(\d+)").unwrap();
}

#[derive(Debug, Deserialize)]
enum FixtureType {
  #[serde(rename = "action")]
  Action,
  #[serde(rename = "change")]
  Change,
  #[serde(rename = "completion")]
  Completion,
  #[serde(rename = "highlight")]
  Highlight,
  #[serde(rename = "hover")]
  Hover,
}

#[derive(Debug, Deserialize)]
struct FixtureMessage {
  #[serde(rename = "type")]
  fixture_type: FixtureType,
  params: Value,
}

#[derive(Debug, Deserialize, Serialize)]
struct LspResponseError {
  code: i32,
  message: String,
  data: Option<Value>,
}

#[derive(Debug)]
enum LspMessage {
  Notification(String, Option<Value>),
  Request(u64, String, Option<Value>),
  Response(u64, Option<Value>, Option<LspResponseError>),
}

impl<'a> From<&'a [u8]> for LspMessage {
  fn from(s: &'a [u8]) -> Self {
    let value: Value = serde_json::from_slice(s).unwrap();
    let obj = value.as_object().unwrap();
    if obj.contains_key("id") && obj.contains_key("method") {
      let id = obj.get("id").unwrap().as_u64().unwrap();
      let method = obj.get("method").unwrap().as_str().unwrap().to_string();
      Self::Request(id, method, obj.get("params").cloned())
    } else if obj.contains_key("id") {
      let id = obj.get("id").unwrap().as_u64().unwrap();
      let maybe_error: Option<LspResponseError> = obj
        .get("error")
        .map(|v| serde_json::from_value(v.clone()).unwrap());
      Self::Response(id, obj.get("result").cloned(), maybe_error)
    } else {
      assert!(obj.contains_key("method"));
      let method = obj.get("method").unwrap().as_str().unwrap().to_string();
      Self::Notification(method, obj.get("params").cloned())
    }
  }
}

struct LspClient {
  reader: std::io::BufReader<ChildStdout>,
  child: std::process::Child,
  request_id: u64,
  start: Instant,
  writer: std::io::BufWriter<ChildStdin>,
}

fn read_message<R>(reader: &mut R) -> Result<Vec<u8>, AnyError>
where
  R: Read + BufRead,
{
  let mut content_length = 0_usize;
  loop {
    let mut buf = String::new();
    reader.read_line(&mut buf)?;
    if let Some(captures) = CONTENT_TYPE_REG.captures(&buf) {
      let content_length_match = captures
        .get(1)
        .ok_or_else(|| generic_error("missing capture"))?;
      content_length = content_length_match.as_str().parse::<usize>()?;
    }
    if &buf == "\r\n" {
      break;
    }
  }

  let mut msg_buf = vec![0_u8; content_length];
  reader.read_exact(&mut msg_buf)?;
  Ok(msg_buf)
}

impl Drop for LspClient {
  fn drop(&mut self) {
    match self.child.try_wait() {
      Ok(None) => {
        self.child.kill().unwrap();
        let _ = self.child.wait();
      }
      Ok(Some(status)) => panic!("deno lsp exited unexpectedly {}", status),
      Err(e) => panic!("pebble error: {}", e),
    }
  }
}

impl LspClient {
  fn new(deno_exe: &Path) -> Result<Self, AnyError> {
    let mut child = Command::new(deno_exe)
      .arg("lsp")
      .stdin(Stdio::piped())
      .stdout(Stdio::piped())
      .stderr(Stdio::null())
      .spawn()?;

    let stdout = child.stdout.take().unwrap();
    let reader = std::io::BufReader::new(stdout);

    let stdin = child.stdin.take().unwrap();
    let writer = std::io::BufWriter::new(stdin);

    Ok(Self {
      child,
      reader,
      request_id: 1,
      start: Instant::now(),
      writer,
    })
  }

  fn duration(&self) -> Duration {
    self.start.elapsed()
  }

  fn read(&mut self) -> Result<LspMessage, AnyError> {
    let msg_buf = read_message(&mut self.reader)?;
    let msg = LspMessage::from(msg_buf.as_slice());
    Ok(msg)
  }

  fn read_notification<R>(&mut self) -> Result<(String, Option<R>), AnyError>
  where
    R: de::DeserializeOwned,
  {
    loop {
      if let LspMessage::Notification(method, maybe_params) = self.read()? {
        if let Some(p) = maybe_params {
          let params = serde_json::from_value(p)?;
          return Ok((method, Some(params)));
        } else {
          return Ok((method, None));
        }
      }
    }
  }

  #[allow(unused)]
  fn read_request<R>(&mut self) -> Result<(u64, String, Option<R>), AnyError>
  where
    R: de::DeserializeOwned,
  {
    loop {
      if let LspMessage::Request(id, method, maybe_params) = self.read()? {
        if let Some(p) = maybe_params {
          let params = serde_json::from_value(p)?;
          return Ok((id, method, Some(params)));
        } else {
          return Ok((id, method, None));
        }
      }
    }
  }

  fn write(&mut self, value: Value) -> Result<(), AnyError> {
    let value_str = value.to_string();
    let msg = format!(
      "Content-Length: {}\r\n\r\n{}",
      value_str.as_bytes().len(),
      value_str
    );
    self.writer.write_all(msg.as_bytes())?;
    self.writer.flush()?;
    Ok(())
  }

  fn write_request<S, V>(
    &mut self,
    method: S,
    params: V,
  ) -> Result<(Option<Value>, Option<LspResponseError>), AnyError>
  where
    S: AsRef<str>,
    V: Serialize,
  {
    let value = json!({
      "jsonrpc": "2.0",
      "id": self.request_id,
      "method": method.as_ref(),
      "params": params,
    });
    self.write(value)?;

    loop {
      if let LspMessage::Response(id, result, error) = self.read()? {
        assert_eq!(id, self.request_id);
        self.request_id += 1;
        return Ok((result, error));
      }
    }
  }

  #[allow(unused)]
  fn write_response<V>(&mut self, id: u64, result: V) -> Result<(), AnyError>
  where
    V: Serialize,
  {
    let value = json!({
      "jsonrpc": "2.0",
      "id": id,
      "result": result
    });
    self.write(value)
  }

  fn write_notification<S, V>(
    &mut self,
    method: S,
    params: V,
  ) -> Result<(), AnyError>
  where
    S: AsRef<str>,
    V: Serialize,
  {
    let value = json!({
      "jsonrpc": "2.0",
      "method": method.as_ref(),
      "params": params,
    });
    self.write(value)?;
    Ok(())
  }
}

/// A benchmark that opens a 8000+ line TypeScript document, adds a function to
/// the end of the document and does a level of hovering and gets quick fix
/// code actions.
fn bench_big_file_edits(deno_exe: &Path) -> Result<Duration, AnyError> {
  let mut client = LspClient::new(deno_exe)?;

  let params: Value = serde_json::from_slice(FIXTURE_INIT_JSON)?;
  let (_, response_error): (Option<Value>, Option<LspResponseError>) =
    client.write_request("initialize", params)?;
  assert!(response_error.is_none());

  client.write_notification("initialized", json!({}))?;

  client.write_notification(
    "textDocument/didOpen",
    json!({
      "textDocument": {
        "uri": "file:///fixtures/db.ts",
        "languageId": "typescript",
        "version": 1,
        "text": FIXTURE_DB_TS
      }
    }),
  )?;

  // TODO(@kitsonk) work around https://github.com/denoland/deno/issues/10603
  // let (id, method, _): (u64, String, Option<Value>) = client.read_request()?;
  // assert_eq!(method, "workspace/configuration");

  // client.write_response(
  //   id,
  //   json!({
  //     "enable": true
  //   }),
  // )?;

  let (method, _): (String, Option<Value>) = client.read_notification()?;
  assert_eq!(method, "textDocument/publishDiagnostics");
  let (method, _): (String, Option<Value>) = client.read_notification()?;
  assert_eq!(method, "textDocument/publishDiagnostics");
  let (method, _): (String, Option<Value>) = client.read_notification()?;
  assert_eq!(method, "textDocument/publishDiagnostics");

  let messages: Vec<FixtureMessage> =
    serde_json::from_slice(FIXTURE_DB_MESSAGES)?;

  for msg in messages {
    match msg.fixture_type {
      FixtureType::Action => {
        client.write_request("textDocument/codeAction", msg.params)?;
      }
      FixtureType::Change => {
        client.write_notification("textDocument/didChange", msg.params)?;
      }
      FixtureType::Completion => {
        client.write_request("textDocument/completion", msg.params)?;
      }
      FixtureType::Highlight => {
        client.write_request("textDocument/documentHighlight", msg.params)?;
      }
      FixtureType::Hover => {
        client.write_request("textDocument/hover", msg.params)?;
      }
    }
  }

  let (_, response_error): (Option<Value>, Option<LspResponseError>) =
    client.write_request("shutdown", json!(null))?;
  assert!(response_error.is_none());

  client.write_notification("exit", json!(null))?;

  Ok(client.duration())
}

/// A test that starts up the LSP, opens a single line document, and exits.
fn bench_startup_shutdown(deno_exe: &Path) -> Result<Duration, AnyError> {
  let mut client = LspClient::new(deno_exe)?;

  let params: Value = serde_json::from_slice(FIXTURE_INIT_JSON)?;
  let (_, response_error): (Option<Value>, Option<LspResponseError>) =
    client.write_request("initialize", params)?;
  assert!(response_error.is_none());

  client.write_notification("initialized", json!({}))?;

  client.write_notification(
    "textDocument/didOpen",
    json!({
      "textDocument": {
        "uri": "file:///a/file.ts",
        "languageId": "typescript",
        "version": 1,
        "text": "console.log(Deno.args);\n"
      }
    }),
  )?;

  // TODO(@kitsonk) work around https://github.com/denoland/deno/issues/10603
  // let (id, method, _): (u64, String, Option<Value>) = client.read_request()?;
  // assert_eq!(method, "workspace/configuration");

  // client.write_response(
  //   id,
  //   json!({
  //     "enable": true
  //   }),
  // )?;

  let (method, _): (String, Option<Value>) = client.read_notification()?;
  assert_eq!(method, "textDocument/publishDiagnostics");
  let (method, _): (String, Option<Value>) = client.read_notification()?;
  assert_eq!(method, "textDocument/publishDiagnostics");
  let (method, _): (String, Option<Value>) = client.read_notification()?;
  assert_eq!(method, "textDocument/publishDiagnostics");

  let (_, response_error): (Option<Value>, Option<LspResponseError>) =
    client.write_request("shutdown", json!(null))?;
  assert!(response_error.is_none());

  client.write_notification("exit", json!(null))?;

  Ok(client.duration())
}

/// Generate benchmarks for the LSP server.
pub(crate) fn benchmarks(
  deno_exe: &Path,
) -> Result<HashMap<String, u64>, AnyError> {
  println!("-> Start benchmarking lsp");
  let mut exec_times = HashMap::new();

  println!("   - Simple Startup/Shutdown ");
  let mut times = Vec::new();
  for _ in 0..10 {
    times.push(bench_startup_shutdown(deno_exe)?);
  }
  let mean =
    (times.iter().sum::<Duration>() / times.len() as u32).as_millis() as u64;
  println!("      ({} runs, mean: {}ms)", times.len(), mean);
  exec_times.insert("startup_shutdown".to_string(), mean);

  println!("   - Big Document/Several Edits ");
  let mut times = Vec::new();
  for _ in 0..5 {
    times.push(bench_big_file_edits(deno_exe)?);
  }
  let mean =
    (times.iter().sum::<Duration>() / times.len() as u32).as_millis() as u64;
  println!("      ({} runs, mean: {}ms)", times.len(), mean);
  exec_times.insert("big_file_edits".to_string(), mean);

  println!("<- End benchmarking lsp");

  Ok(exec_times)
}

#[cfg(test)]
mod tests {
  #[test]
  fn test_read_message() {
    let msg = b"content-length: 11\r\n\r\nhello world";
    let reader = std::io::Cursor::new(msg);
    assert_eq!(read_message(reader).unwrap(), b"hello world");
  }
}