feat(fmt): add support for configuration file (#11944)

This commit adds support for configuration file for "deno fmt"
subcommand. It is also respected by LSP when formatting
files.

Example configuration:
{
    "fmt": {
        "files": {
            "include": ["src/"],
            "exclude": ["src/testdata/"]
        },
        "options": {
            "useTabs": true,
            "lineWidth": 80,
            "indentWidth": 4,
            "singleQuote": true,
            "textWrap": "preserve"
        }
    }
}

23 files changed, 687 insertions, 92 deletions

diff --git a/.dprint.json b/.dprint.json
index fcba86c7b..56397dfd9 100644
--- a/.dprint.json
+++ b/.dprint.json
@@ -24,6 +24,7 @@
     "cli/tests/testdata/badly_formatted.md",
     "cli/tests/testdata/badly_formatted.json",
     "cli/tests/testdata/byte_order_mark.ts",
+    "cli/tests/testdata/fmt/*",
     "cli/tsc/*typescript.js",
     "test_util/std",
     "test_util/wpt",
diff --git a/cli/config_file.rs b/cli/config_file.rs
index 94373334a..dd002ca97 100644
--- a/cli/config_file.rs
+++ b/cli/config_file.rs
@@ -277,7 +277,7 @@ pub struct LintRulesConfig {
 
 #[derive(Clone, Debug, Default, Deserialize)]
 #[serde(default, deny_unknown_fields)]
-pub struct LintFilesConfig {
+pub struct FilesConfig {
   pub include: Vec<String>,
   pub exclude: Vec<String>,
 }
@@ -286,7 +286,32 @@ pub struct LintFilesConfig {
 #[serde(default, deny_unknown_fields)]
 pub struct LintConfig {
   pub rules: LintRulesConfig,
-  pub files: LintFilesConfig,
+  pub files: FilesConfig,
+}
+
+#[derive(Clone, Copy, Debug, Deserialize)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+pub enum ProseWrap {
+  Always,
+  Never,
+  Preserve,
+}
+
+#[derive(Clone, Debug, Default, Deserialize)]
+#[serde(default, deny_unknown_fields, rename_all = "camelCase")]
+pub struct FmtOptionsConfig {
+  pub use_tabs: Option<bool>,
+  pub line_width: Option<u32>,
+  pub indent_width: Option<u8>,
+  pub single_quote: Option<bool>,
+  pub prose_wrap: Option<ProseWrap>,
+}
+
+#[derive(Clone, Debug, Default, Deserialize)]
+#[serde(default, deny_unknown_fields)]
+pub struct FmtConfig {
+  pub options: FmtOptionsConfig,
+  pub files: FilesConfig,
 }
 
 #[derive(Clone, Debug, Deserialize)]
@@ -294,6 +319,7 @@ pub struct LintConfig {
 pub struct ConfigFileJson {
   pub compiler_options: Option<Value>,
   pub lint: Option<Value>,
+  pub fmt: Option<Value>,
 }
 
 #[derive(Clone, Debug)]
@@ -374,6 +400,16 @@ impl ConfigFile {
       Ok(None)
     }
   }
+
+  pub fn to_fmt_config(&self) -> Result<Option<FmtConfig>, AnyError> {
+    if let Some(config) = self.json.fmt.clone() {
+      let fmt_config: FmtConfig = serde_json::from_value(config)
+        .context("Failed to parse \"fmt\" configuration")?;
+      Ok(Some(fmt_config))
+    } else {
+      Ok(None)
+    }
+  }
 }
 
 #[cfg(test)]
@@ -441,6 +477,19 @@ mod tests {
           "tags": ["recommended"],
           "include": ["ban-untagged-todo"]
         }
+      },
+      "fmt": {
+        "files": {
+          "include": ["src/"],
+          "exclude": ["src/testdata/"]
+        },
+        "options": {
+          "useTabs": true,
+          "lineWidth": 80,
+          "indentWidth": 4,
+          "singleQuote": true,
+          "proseWrap": "preserve"
+        }
       }
     }"#;
     let config_path = PathBuf::from("/deno/tsconfig.json");
@@ -474,6 +523,17 @@ mod tests {
       Some(vec!["recommended".to_string()])
     );
     assert!(lint_config.rules.exclude.is_none());
+
+    let fmt_config = config_file
+      .to_fmt_config()
+      .expect("error parsing fmt object")
+      .expect("fmt object should be defined");
+    assert_eq!(fmt_config.files.include, vec!["src/"]);
+    assert_eq!(fmt_config.files.exclude, vec!["src/testdata/"]);
+    assert_eq!(fmt_config.options.use_tabs, Some(true));
+    assert_eq!(fmt_config.options.line_width, Some(80));
+    assert_eq!(fmt_config.options.indent_width, Some(4));
+    assert_eq!(fmt_config.options.single_quote, Some(true));
   }
 
   #[test]
diff --git a/cli/flags.rs b/cli/flags.rs
index b35b7bad7..eb7d0901f 100644
--- a/cli/flags.rs
+++ b/cli/flags.rs
@@ -815,6 +815,7 @@ Ignore formatting a file by adding an ignore comment at the top of the file:
 
   // deno-fmt-ignore-file",
     )
+    .arg(config_arg())
     .arg(
       Arg::with_name("check")
         .long("check")
@@ -1732,6 +1733,7 @@ fn eval_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
 }
 
 fn fmt_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
+  config_arg_parse(flags, matches);
   flags.watch = matches.is_present("watch");
   let files = match matches.values_of("files") {
     Some(f) => f.map(PathBuf::from).collect(),
@@ -2534,6 +2536,44 @@ mod tests {
         ..Flags::default()
       }
     );
+
+    let r = flags_from_vec(svec!["deno", "fmt", "--config", "deno.jsonc"]);
+    assert_eq!(
+      r.unwrap(),
+      Flags {
+        subcommand: DenoSubcommand::Fmt(FmtFlags {
+          ignore: vec![],
+          check: false,
+          files: vec![],
+          ext: "ts".to_string()
+        }),
+        config_path: Some("deno.jsonc".to_string()),
+        ..Flags::default()
+      }
+    );
+
+    let r = flags_from_vec(svec![
+      "deno",
+      "fmt",
+      "--config",
+      "deno.jsonc",
+      "--watch",
+      "foo.ts"
+    ]);
+    assert_eq!(
+      r.unwrap(),
+      Flags {
+        subcommand: DenoSubcommand::Fmt(FmtFlags {
+          ignore: vec![],
+          check: false,
+          files: vec![PathBuf::from("foo.ts")],
+          ext: "ts".to_string()
+        }),
+        config_path: Some("deno.jsonc".to_string()),
+        watch: true,
+        ..Flags::default()
+      }
+    );
   }
 
   #[test]
diff --git a/cli/lsp/language_server.rs b/cli/lsp/language_server.rs
index 3f1bfc923..87fc5f7e5 100644
--- a/cli/lsp/language_server.rs
+++ b/cli/lsp/language_server.rs
@@ -336,15 +336,15 @@ impl Inner {
     Ok(navigation_tree)
   }
 
-  fn merge_user_tsconfig(
-    &mut self,
-    maybe_config: &Option<String>,
-    maybe_root_uri: &Option<Url>,
-    tsconfig: &mut TsConfig,
-  ) -> Result<(), AnyError> {
-    self.maybe_config_file = None;
-    self.maybe_config_uri = None;
-    if let Some(config_str) = maybe_config {
+  /// Returns a tuple with parsed `ConfigFile` and `Url` pointing to that file.
+  /// If there's no config file specified in settings returns `None`.
+  fn get_config_file_and_url(
+    &self,
+  ) -> Result<Option<(ConfigFile, Url)>, AnyError> {
+    let workspace_settings = self.config.get_workspace_settings();
+    let maybe_root_uri = self.config.root_uri.clone();
+    let maybe_config = workspace_settings.config;
+    if let Some(config_str) = &maybe_config {
       if !config_str.is_empty() {
         info!("Setting TypeScript configuration from: \"{}\"", config_str);
         let config_url = if let Ok(url) = Url::from_file_path(config_str) {
@@ -374,18 +374,34 @@ impl Inner {
             .ok_or_else(|| anyhow!("Bad uri: \"{}\"", config_url))?;
           ConfigFile::read(path)?
         };
-        let (value, maybe_ignored_options) =
-          config_file.to_compiler_options()?;
-        tsconfig.merge(&value);
-        self.maybe_config_file = Some(config_file);
-        self.maybe_config_uri = Some(config_url);
-        if let Some(ignored_options) = maybe_ignored_options {
-          // TODO(@kitsonk) turn these into diagnostics that can be sent to the
-          // client
-          warn!("{}", ignored_options);
-        }
+        return Ok(Some((config_file, config_url)));
+      }
+    }
+
+    Ok(None)
+  }
+
+  fn merge_user_tsconfig(
+    &mut self,
+    tsconfig: &mut TsConfig,
+  ) -> Result<(), AnyError> {
+    self.maybe_config_file = None;
+    self.maybe_config_uri = None;
+
+    let maybe_file_and_url = self.get_config_file_and_url()?;
+
+    if let Some((config_file, config_url)) = maybe_file_and_url {
+      let (value, maybe_ignored_options) = config_file.to_compiler_options()?;
+      tsconfig.merge(&value);
+      self.maybe_config_file = Some(config_file);
+      self.maybe_config_uri = Some(config_url);
+      if let Some(ignored_options) = maybe_ignored_options {
+        // TODO(@kitsonk) turn these into diagnostics that can be sent to the
+        // client
+        warn!("{}", ignored_options);
       }
     }
+
     Ok(())
   }
 
@@ -575,20 +591,15 @@ impl Inner {
       // TODO(@kitsonk) remove for Deno 1.15
       "useUnknownInCatchVariables": false,
     }));
-    let (maybe_config, maybe_root_uri) = {
-      let config = &self.config;
-      let workspace_settings = config.get_workspace_settings();
-      if workspace_settings.unstable {
-        let unstable_libs = json!({
-          "lib": ["deno.ns", "deno.window", "deno.unstable"]
-        });
-        tsconfig.merge(&unstable_libs);
-      }
-      (workspace_settings.config, config.root_uri.clone())
-    };
-    if let Err(err) =
-      self.merge_user_tsconfig(&maybe_config, &maybe_root_uri, &mut tsconfig)
-    {
+    let config = &self.config;
+    let workspace_settings = config.get_workspace_settings();
+    if workspace_settings.unstable {
+      let unstable_libs = json!({
+        "lib": ["deno.ns", "deno.window", "deno.unstable"]
+      });
+      tsconfig.merge(&unstable_libs);
+    }
+    if let Err(err) = self.merge_user_tsconfig(&mut tsconfig) {
       self.client.show_message(MessageType::Warning, err).await;
     }
     let _ok: bool = self
@@ -1015,14 +1026,37 @@ impl Inner {
         PathBuf::from(params.text_document.uri.path())
       };
 
+    let maybe_file_and_url = self.get_config_file_and_url().map_err(|err| {
+      error!("Unable to parse configuration file: {}", err);
+      LspError::internal_error()
+    })?;
+
+    let fmt_options = if let Some((config_file, _)) = maybe_file_and_url {
+      config_file
+        .to_fmt_config()
+        .map_err(|err| {
+          error!("Unable to parse fmt configuration: {}", err);
+          LspError::internal_error()
+        })?
+        .unwrap_or_default()
+    } else {
+      Default::default()
+    };
+
     let source = document_data.source().clone();
     let text_edits = tokio::task::spawn_blocking(move || {
       let format_result = match source.module() {
-        Some(Ok(parsed_module)) => Ok(format_parsed_module(parsed_module)),
+        Some(Ok(parsed_module)) => {
+          Ok(format_parsed_module(parsed_module, fmt_options.options))
+        }
         Some(Err(err)) => Err(err.to_string()),
         None => {
           // it's not a js/ts file, so attempt to format its contents
-          format_file(&file_path, source.text_info().text_str())
+          format_file(
+            &file_path,
+            source.text_info().text_str(),
+            fmt_options.options,
+          )
         }
       };
 
diff --git a/cli/main.rs b/cli/main.rs
index 896704eec..55de5a61e 100644
--- a/cli/main.rs
+++ b/cli/main.rs
@@ -805,8 +805,20 @@ async fn format_command(
   flags: Flags,
   fmt_flags: FmtFlags,
 ) -> Result<(), AnyError> {
+  let program_state = ProgramState::build(flags.clone()).await?;
+  let maybe_fmt_config =
+    if let Some(config_file) = &program_state.maybe_config_file {
+      config_file.to_fmt_config()?
+    } else {
+      None
+    };
+
   if fmt_flags.files.len() == 1 && fmt_flags.files[0].to_string_lossy() == "-" {
-    return tools::fmt::format_stdin(fmt_flags.check, fmt_flags.ext);
+    return tools::fmt::format_stdin(
+      fmt_flags.check,
+      fmt_flags.ext,
+      maybe_fmt_config.map(|c| c.options).unwrap_or_default(),
+    );
   }
 
   tools::fmt::format(
@@ -814,6 +826,7 @@ async fn format_command(
     fmt_flags.ignore,
     fmt_flags.check,
     flags.watch,
+    maybe_fmt_config,
   )
   .await?;
   Ok(())
diff --git a/cli/tests/integration/fmt_tests.rs b/cli/tests/integration/fmt_tests.rs
index 00565a5d0..2d7451694 100644
--- a/cli/tests/integration/fmt_tests.rs
+++ b/cli/tests/integration/fmt_tests.rs
@@ -129,25 +129,25 @@ fn fmt_ignore_unexplicit_files() {
 }
 
 itest!(fmt_check_tests_dir {
-  args: "fmt --check ./ --ignore=.test_coverage",
+  args: "fmt --check ./ --ignore=.test_coverage,fmt/fmt_with_config/",
   output: "fmt/expected_fmt_check_tests_dir.out",
   exit_code: 1,
 });
 
 itest!(fmt_quiet_check_fmt_dir {
-  args: "fmt --check --quiet fmt/",
+  args: "fmt --check --quiet fmt/regular/",
   output_str: Some(""),
   exit_code: 0,
 });
 
 itest!(fmt_check_formatted_files {
-    args: "fmt --check fmt/formatted1.js fmt/formatted2.ts fmt/formatted3.md fmt/formatted4.jsonc",
+    args: "fmt --check fmt/regular/formatted1.js fmt/regular/formatted2.ts fmt/regular/formatted3.md fmt/regular/formatted4.jsonc",
     output: "fmt/expected_fmt_check_formatted_files.out",
     exit_code: 0,
   });
 
 itest!(fmt_check_ignore {
-  args: "fmt --check --ignore=fmt/formatted1.js fmt/",
+  args: "fmt --check --ignore=fmt/regular/formatted1.js fmt/regular/",
   output: "fmt/expected_fmt_check_ignore.out",
   exit_code: 0,
 });
@@ -181,3 +181,26 @@ itest!(fmt_stdin_check_not_formatted {
   input: Some("const a = 1\n"),
   output_str: Some("Not formatted stdin\n"),
 });
+
+itest!(fmt_with_config {
+  args: "fmt --config fmt/deno.jsonc fmt/fmt_with_config/",
+  output: "fmt/fmt_with_config.out",
+});
+
+// Check if CLI flags take precedence
+itest!(fmt_with_config_and_flags {
+  args: "fmt --config fmt/deno.jsonc --ignore=fmt/fmt_with_config/a.ts,fmt/fmt_with_config/b.ts",
+  output: "fmt/fmt_with_config_and_flags.out",
+});
+
+itest!(fmt_with_malformed_config {
+  args: "fmt --config fmt/deno.malformed.jsonc",
+  output: "fmt/fmt_with_malformed_config.out",
+  exit_code: 1,
+});
+
+itest!(fmt_with_malformed_config2 {
+  args: "fmt --config fmt/deno.malformed2.jsonc",
+  output: "fmt/fmt_with_malformed_config2.out",
+  exit_code: 1,
+});
diff --git a/cli/tests/integration/lsp_tests.rs b/cli/tests/integration/lsp_tests.rs
index 1b8d35108..3d87c222d 100644
--- a/cli/tests/integration/lsp_tests.rs
+++ b/cli/tests/integration/lsp_tests.rs
@@ -3197,6 +3197,169 @@ fn lsp_format_markdown() {
 }
 
 #[test]
+fn lsp_format_with_config() {
+  let temp_dir = TempDir::new().expect("could not create temp dir");
+  let mut params: lsp::InitializeParams =
+    serde_json::from_value(load_fixture("initialize_params.json")).unwrap();
+  let deno_fmt_jsonc =
+    serde_json::to_vec_pretty(&load_fixture("deno.fmt.jsonc")).unwrap();
+  fs::write(temp_dir.path().join("deno.fmt.jsonc"), deno_fmt_jsonc).unwrap();
+
+  params.root_uri = Some(Url::from_file_path(temp_dir.path()).unwrap());
+  if let Some(Value::Object(mut map)) = params.initialization_options {
+    map.insert("config".to_string(), json!("./deno.fmt.jsonc"));
+    params.initialization_options = Some(Value::Object(map));
+  }
+
+  let deno_exe = deno_exe_path();
+  let mut client = LspClient::new(&deno_exe).unwrap();
+  client
+    .write_request::<_, _, Value>("initialize", params)
+    .unwrap();
+
+  client
+    .write_notification(
+      "textDocument/didOpen",
+      json!({
+        "textDocument": {
+          "uri": "file:///a/file.ts",
+          "languageId": "typescript",
+          "version": 1,
+          "text": "export async function someVeryLongFunctionName() {\nconst response = fetch(\"http://localhost:4545/some/non/existent/path.json\");\nconsole.log(response.text());\nconsole.log(\"finished!\")\n}"
+        }
+      }),
+    )
+    .unwrap();
+
+  // The options below should be ignored in favor of configuration from config file.
+  let (maybe_res, maybe_err) = client
+    .write_request::<_, _, Value>(
+      "textDocument/formatting",
+      json!({
+        "textDocument": {
+          "uri": "file:///a/file.ts"
+        },
+        "options": {
+          "tabSize": 2,
+          "insertSpaces": true
+        }
+      }),
+    )
+    .unwrap();
+
+  assert!(maybe_err.is_none());
+  assert_eq!(
+    maybe_res,
+    Some(json!([{
+        "range": {
+          "start": {
+            "line": 1,
+            "character": 0
+          },
+          "end": {
+            "line": 1,
+            "character": 0
+          }
+        },
+        "newText": "\t"
+      },
+      {
+        "range": {
+          "start": {
+            "line": 1,
+            "character": 23
+          },
+          "end": {
+            "line": 1,
+            "character": 24
+          }
+        },
+        "newText": "\n\t\t'"
+      },
+      {
+        "range": {
+          "start": {
+            "line": 1,
+            "character": 73
+          },
+          "end": {
+            "line": 1,
+            "character": 74
+          }
+        },
+        "newText": "',\n\t"
+      },
+      {
+        "range": {
+          "start": {
+            "line": 2,
+            "character": 0
+          },
+          "end": {
+            "line": 2,
+            "character": 0
+          }
+        },
+        "newText": "\t"
+      },
+      {
+        "range": {
+          "start": {
+            "line": 3,
+            "character": 0
+          },
+          "end": {
+            "line": 3,
+            "character": 0
+          }
+        },
+        "newText": "\t"
+      },
+      {
+        "range": {
+          "start": {
+            "line": 3,
+            "character": 12
+          },
+          "end": {
+            "line": 3,
+            "character": 13
+          }
+        },
+        "newText": "'"
+      },
+      {
+        "range": {
+          "start": {
+            "line": 3,
+            "character": 22
+          },
+          "end": {
+            "line": 3,
+            "character": 24
+          }
+        },
+        "newText": "');"
+      },
+      {
+        "range": {
+          "start": {
+            "line": 4,
+            "character": 1
+          },
+          "end": {
+            "line": 4,
+            "character": 1
+          }
+        },
+        "newText": "\n"
+      }]
+    ))
+  );
+  shutdown(&mut client);
+}
+
+#[test]
 fn lsp_markdown_no_diagnostics() {
   let mut client = init("initialize_params.json");
   client
diff --git a/cli/tests/testdata/fmt/deno.jsonc b/cli/tests/testdata/fmt/deno.jsonc
new file mode 100644
index 000000000..0e682cf36
--- /dev/null
+++ b/cli/tests/testdata/fmt/deno.jsonc
@@ -0,0 +1,15 @@
+{
+  "fmt": {
+    "files": {
+      "include": ["fmt/fmt_with_config/"],
+      "exclude": ["fmt/fmt_with_config/b.ts"]
+    },
+    "options": {
+      "useTabs": true,
+      "lineWidth": 40,
+      "indentWidth": 8,
+      "singleQuote": true,
+      "proseWrap": "always"
+    }
+  }
+}
diff --git a/cli/tests/testdata/fmt/deno.malformed.jsonc b/cli/tests/testdata/fmt/deno.malformed.jsonc
new file mode 100644
index 000000000..667480bdc
--- /dev/null
+++ b/cli/tests/testdata/fmt/deno.malformed.jsonc
@@ -0,0 +1,12 @@
+{
+  "fmt": {
+    "files": {
+      "include": ["fmt/fmt_with_config/"],
+      "exclude": ["fmt/fmt_with_config/b.ts"]
+    },
+    "dont_know_this_field": {},
+    "options": {
+      "useTabs": true
+    }
+  }
+}
diff --git a/cli/tests/testdata/fmt/deno.malformed2.jsonc b/cli/tests/testdata/fmt/deno.malformed2.jsonc
new file mode 100644
index 000000000..2210dc0c7
--- /dev/null
+++ b/cli/tests/testdata/fmt/deno.malformed2.jsonc
@@ -0,0 +1,12 @@
+{
+  "fmt": {
+    "files": {
+      "include": ["fmt/fmt_with_config/"],
+      "exclude": ["fmt/fmt_with_config/b.ts"],
+      "dont_know_this_field": {}
+    },
+    "options": {
+      "useTabs": true
+    }
+  }
+}
diff --git a/cli/tests/testdata/fmt/fmt_with_config.out b/cli/tests/testdata/fmt/fmt_with_config.out
new file mode 100644
index 000000000..158c556c2
--- /dev/null
+++ b/cli/tests/testdata/fmt/fmt_with_config.out
@@ -0,0 +1 @@
+Checked 2 files
diff --git a/cli/tests/testdata/fmt/fmt_with_config/a.ts b/cli/tests/testdata/fmt/fmt_with_config/a.ts
new file mode 100644
index 000000000..e0f32647b
--- /dev/null
+++ b/cli/tests/testdata/fmt/fmt_with_config/a.ts
@@ -0,0 +1,46 @@
+unitTest(
+	{ perms: { net: true } },
+	async function responseClone() {
+		const response =
+			await fetch(
+				'http://localhost:4545/fixture.json',
+			);
+		const response1 =
+			response.clone();
+		assert(
+			response !==
+				response1,
+		);
+		assertEquals(
+			response.status,
+			response1
+				.status,
+		);
+		assertEquals(
+			response.statusText,
+			response1
+				.statusText,
+		);
+		const u8a =
+			new Uint8Array(
+				await response
+					.arrayBuffer(),
+			);
+		const u8a1 =
+			new Uint8Array(
+				await response1
+					.arrayBuffer(),
+			);
+		for (
+			let i = 0;
+			i <
+				u8a.byteLength;
+			i++
+		) {
+			assertEquals(
+				u8a[i],
+				u8a1[i],
+			);
+		}
+	},
+);
diff --git a/cli/tests/testdata/fmt/fmt_with_config/b.ts b/cli/tests/testdata/fmt/fmt_with_config/b.ts
new file mode 100644
index 000000000..5c37d51d2
--- /dev/null
+++ b/cli/tests/testdata/fmt/fmt_with_config/b.ts
@@ -0,0 +1,15 @@
+// This file should be excluded from formatting
+unitTest(
+    { perms: { net: true } },
+    async function fetchBodyUsedCancelStream() {
+      const response = await fetch(
+        "http://localhost:4545/fixture.json",
+      );
+      assert(response.body !== null);
+  
+      assertEquals(response.bodyUsed, false);
+      const promise = response.body.cancel();
+      assertEquals(response.bodyUsed, true);
+      await promise;
+    },
+);
\ No newline at end of file
diff --git a/cli/tests/testdata/fmt/fmt_with_config/c.md b/cli/tests/testdata/fmt/fmt_with_config/c.md
new file mode 100644
index 000000000..012f7e3d4
--- /dev/null
+++ b/cli/tests/testdata/fmt/fmt_with_config/c.md
@@ -0,0 +1,17 @@
+## Permissions
+
+Deno is secure by default. Therefore,
+unless you specifically enable it, a
+program run with Deno has no file,
+network, or environment access. Access
+to security sensitive functionality
+requires that permisisons have been
+granted to an executing script through
+command line flags, or a runtime
+permission prompt.
+
+For the following example `mod.ts` has
+been granted read-only access to the
+file system. It cannot write to the file
+system, or perform any other security
+sensitive functions.
diff --git a/cli/tests/testdata/fmt/fmt_with_config_and_flags.out b/cli/tests/testdata/fmt/fmt_with_config_and_flags.out
new file mode 100644
index 000000000..c05ac45a1
--- /dev/null
+++ b/cli/tests/testdata/fmt/fmt_with_config_and_flags.out
@@ -0,0 +1 @@
+Checked 1 file
diff --git a/cli/tests/testdata/fmt/fmt_with_malformed_config.out b/cli/tests/testdata/fmt/fmt_with_malformed_config.out
new file mode 100644
index 000000000..1a55613ef
--- /dev/null
+++ b/cli/tests/testdata/fmt/fmt_with_malformed_config.out
@@ -0,0 +1,4 @@
+error: Failed to parse "fmt" configuration
+
+Caused by:
+    unknown field `dont_know_this_field`, expected `options` or `files`
diff --git a/cli/tests/testdata/fmt/fmt_with_malformed_config2.out b/cli/tests/testdata/fmt/fmt_with_malformed_config2.out
new file mode 100644
index 000000000..948b6b5b8
--- /dev/null
+++ b/cli/tests/testdata/fmt/fmt_with_malformed_config2.out
@@ -0,0 +1,4 @@
+error: Failed to parse "fmt" configuration
+
+Caused by:
+    unknown field `dont_know_this_field`, expected `include` or `exclude`
diff --git a/cli/tests/testdata/fmt/formatted1.js b/cli/tests/testdata/fmt/regular/formatted1.js
index 587aa5b96..587aa5b96 100644
--- a/cli/tests/testdata/fmt/formatted1.js
+++ b/cli/tests/testdata/fmt/regular/formatted1.js
diff --git a/cli/tests/testdata/fmt/formatted2.ts b/cli/tests/testdata/fmt/regular/formatted2.ts
index 4a8036806..4a8036806 100644
--- a/cli/tests/testdata/fmt/formatted2.ts
+++ b/cli/tests/testdata/fmt/regular/formatted2.ts
diff --git a/cli/tests/testdata/fmt/formatted3.md b/cli/tests/testdata/fmt/regular/formatted3.md
index e6e616584..e6e616584 100644
--- a/cli/tests/testdata/fmt/formatted3.md
+++ b/cli/tests/testdata/fmt/regular/formatted3.md
diff --git a/cli/tests/testdata/fmt/formatted4.jsonc b/cli/tests/testdata/fmt/regular/formatted4.jsonc
index f0f72a6ed..f0f72a6ed 100644
--- a/cli/tests/testdata/fmt/formatted4.jsonc
+++ b/cli/tests/testdata/fmt/regular/formatted4.jsonc
diff --git a/cli/tests/testdata/lsp/deno.fmt.jsonc b/cli/tests/testdata/lsp/deno.fmt.jsonc
new file mode 100644
index 000000000..a0a851731
--- /dev/null
+++ b/cli/tests/testdata/lsp/deno.fmt.jsonc
@@ -0,0 +1,11 @@
+{
+  "fmt": {
+    "options": {
+      "useTabs": true,
+      "lineWidth": 40,
+      "indentWidth": 8,
+      "singleQuote": true,
+      "proseWrap": "always"
+    }
+  }
+}
diff --git a/cli/tools/fmt.rs b/cli/tools/fmt.rs
index b3dfc86e8..5f1507d19 100644
--- a/cli/tools/fmt.rs
+++ b/cli/tools/fmt.rs
@@ -8,6 +8,9 @@
 //! the same functions as ops available in JS runtime.
 
 use crate::colors;
+use crate::config_file::FmtConfig;
+use crate::config_file::FmtOptionsConfig;
+use crate::config_file::ProseWrap;
 use crate::diff::diff;
 use crate::file_watcher;
 use crate::file_watcher::ResolutionResult;
@@ -35,24 +38,57 @@ pub async fn format(
   ignore: Vec<PathBuf>,
   check: bool,
   watch: bool,
+  maybe_fmt_config: Option<FmtConfig>,
 ) -> Result<(), AnyError> {
+  // First, prepare final configuration.
+  // Collect included and ignored files. CLI flags take precendence
+  // over config file, ie. if there's `files.ignore` in config file
+  // and `--ignore` CLI flag, only the flag value is taken into account.
+  let mut include_files = args.clone();
+  let mut exclude_files = ignore;
+
+  if let Some(fmt_config) = maybe_fmt_config.as_ref() {
+    if include_files.is_empty() {
+      include_files = fmt_config
+        .files
+        .include
+        .iter()
+        .map(PathBuf::from)
+        .collect::<Vec<PathBuf>>();
+    }
+
+    if exclude_files.is_empty() {
+      exclude_files = fmt_config
+        .files
+        .exclude
+        .iter()
+        .map(PathBuf::from)
+        .collect::<Vec<PathBuf>>();
+    }
+  }
+
+  let fmt_options = maybe_fmt_config.map(|c| c.options).unwrap_or_default();
+
   let resolver = |changed: Option<Vec<PathBuf>>| {
     let files_changed = changed.is_some();
     let result =
-      collect_files(&args, &ignore, is_supported_ext_fmt).map(|files| {
-        if let Some(paths) = changed {
-          files
-            .into_iter()
-            .filter(|path| paths.contains(path))
-            .collect::<Vec<_>>()
-        } else {
-          files
-        }
-      });
-    let paths_to_watch = args.clone();
+      collect_files(&include_files, &exclude_files, is_supported_ext_fmt).map(
+        |files| {
+          let collected_files = if let Some(paths) = changed {
+            files
+              .into_iter()
+              .filter(|path| paths.contains(path))
+              .collect::<Vec<_>>()
+          } else {
+            files
+          };
+          (collected_files, fmt_options.clone())
+        },
+      );
+    let paths_to_watch = include_files.clone();
     async move {
       if (files_changed || !watch)
-        && matches!(result, Ok(ref files) if files.is_empty())
+        && matches!(result, Ok((ref files, _)) if files.is_empty())
       {
         ResolutionResult::Ignore
       } else {
@@ -63,11 +99,11 @@ pub async fn format(
       }
     }
   };
-  let operation = |paths: Vec<PathBuf>| async move {
+  let operation = |(paths, fmt_options): (Vec<PathBuf>, FmtOptionsConfig)| async move {
     if check {
-      check_source_files(paths).await?;
+      check_source_files(paths, fmt_options).await?;
     } else {
-      format_source_files(paths).await?;
+      format_source_files(paths, fmt_options).await?;
     }
     Ok(())
   };
@@ -75,13 +111,13 @@ pub async fn format(
   if watch {
     file_watcher::watch_func(resolver, operation, "Fmt").await?;
   } else {
-    let files =
+    let (files, fmt_options) =
       if let ResolutionResult::Restart { result, .. } = resolver(None).await {
         result?
       } else {
         return Err(generic_error("No target files found."));
       };
-    operation(files).await?;
+    operation((files, fmt_options)).await?;
   }
 
   Ok(())
@@ -89,10 +125,14 @@ pub async fn format(
 
 /// Formats markdown (using <https://github.com/dprint/dprint-plugin-markdown>) and its code blocks
 /// (ts/tsx, js/jsx).
-fn format_markdown(file_text: &str) -> Result<String, String> {
+fn format_markdown(
+  file_text: &str,
+  fmt_options: &FmtOptionsConfig,
+) -> Result<String, String> {
+  let markdown_config = get_resolved_markdown_config(fmt_options);
   dprint_plugin_markdown::format_text(
     file_text,
-    &MARKDOWN_CONFIG,
+    &markdown_config,
     move |tag, text, line_width| {
       let tag = tag.to_lowercase();
       if matches!(
@@ -115,13 +155,14 @@ fn format_markdown(file_text: &str) -> Result<String, String> {
         };
 
         if matches!(extension, "json" | "jsonc") {
-          let mut json_config = JSON_CONFIG.clone();
+          let mut json_config = get_resolved_json_config(fmt_options);
           json_config.line_width = line_width;
           dprint_plugin_json::format_text(text, &json_config)
         } else {
           let fake_filename =
             PathBuf::from(format!("deno_fmt_stdin.{}", extension));
-          let mut codeblock_config = TYPESCRIPT_CONFIG.clone();
+          let mut codeblock_config =
+            get_resolved_typescript_config(fmt_options);
           codeblock_config.line_width = line_width;
           dprint_plugin_typescript::format_text(
             &fake_filename,
@@ -140,32 +181,36 @@ fn format_markdown(file_text: &str) -> Result<String, String> {
 /// Formats JSON and JSONC using the rules provided by .deno()
 /// of configuration builder of <https://github.com/dprint/dprint-plugin-json>.
 /// See <https://git.io/Jt4ht> for configuration.
-fn format_json(file_text: &str) -> Result<String, String> {
-  dprint_plugin_json::format_text(file_text, &JSON_CONFIG)
-    .map_err(|e| e.to_string())
+fn format_json(
+  file_text: &str,
+  fmt_options: &FmtOptionsConfig,
+) -> Result<String, String> {
+  let config = get_resolved_json_config(fmt_options);
+  dprint_plugin_json::format_text(file_text, &config).map_err(|e| e.to_string())
 }
 
 /// Formats a single TS, TSX, JS, JSX, JSONC, JSON, or MD file.
 pub fn format_file(
   file_path: &Path,
   file_text: &str,
+  fmt_options: FmtOptionsConfig,
 ) -> Result<String, String> {
   let ext = get_extension(file_path).unwrap_or_else(String::new);
   if ext == "md" {
-    format_markdown(file_text)
+    format_markdown(file_text, &fmt_options)
   } else if matches!(ext.as_str(), "json" | "jsonc") {
-    format_json(file_text)
+    format_json(file_text, &fmt_options)
   } else {
-    dprint_plugin_typescript::format_text(
-      file_path,
-      file_text,
-      &TYPESCRIPT_CONFIG,
-    )
-    .map_err(|e| e.to_string())
+    let config = get_resolved_typescript_config(&fmt_options);
+    dprint_plugin_typescript::format_text(file_path, file_text, &config)
+      .map_err(|e| e.to_string())
   }
 }
 
-pub fn format_parsed_module(parsed_source: &ParsedSource) -> String {
+pub fn format_parsed_module(
+  parsed_source: &ParsedSource,
+  fmt_options: FmtOptionsConfig,
+) -> String {
   dprint_plugin_typescript::format_parsed_file(
     &dprint_plugin_typescript::SourceFileInfo {
       is_jsx: matches!(
@@ -178,11 +223,14 @@ pub fn format_parsed_module(parsed_source: &ParsedSource) -> String {
       module: parsed_source.module(),
       tokens: parsed_source.tokens(),
     },
-    &TYPESCRIPT_CONFIG,
+    &get_resolved_typescript_config(&fmt_options),
   )
 }
 
-async fn check_source_files(paths: Vec<PathBuf>) -> Result<(), AnyError> {
+async fn check_source_files(
+  paths: Vec<PathBuf>,
+  fmt_options: FmtOptionsConfig,
+) -> Result<(), AnyError> {
   let not_formatted_files_count = Arc::new(AtomicUsize::new(0));
   let checked_files_count = Arc::new(AtomicUsize::new(0));
 
@@ -196,7 +244,7 @@ async fn check_source_files(paths: Vec<PathBuf>) -> Result<(), AnyError> {
       checked_files_count.fetch_add(1, Ordering::Relaxed);
       let file_text = read_file_contents(&file_path)?.text;
 
-      match format_file(&file_path, &file_text) {
+      match format_file(&file_path, &file_text, fmt_options.clone()) {
         Ok(formatted_text) => {
           if formatted_text != file_text {
             not_formatted_files_count.fetch_add(1, Ordering::Relaxed);
@@ -235,7 +283,10 @@ async fn check_source_files(paths: Vec<PathBuf>) -> Result<(), AnyError> {
   }
 }
 
-async fn format_source_files(paths: Vec<PathBuf>) -> Result<(), AnyError> {
+async fn format_source_files(
+  paths: Vec<PathBuf>,
+  fmt_options: FmtOptionsConfig,
+) -> Result<(), AnyError> {
   let formatted_files_count = Arc::new(AtomicUsize::new(0));
   let checked_files_count = Arc::new(AtomicUsize::new(0));
   let output_lock = Arc::new(Mutex::new(0)); // prevent threads outputting at the same time
@@ -247,7 +298,7 @@ async fn format_source_files(paths: Vec<PathBuf>) -> Result<(), AnyError> {
       checked_files_count.fetch_add(1, Ordering::Relaxed);
       let file_contents = read_file_contents(&file_path)?;
 
-      match format_file(&file_path, &file_contents.text) {
+      match format_file(&file_path, &file_contents.text, fmt_options.clone()) {
         Ok(formatted_text) => {
           if formatted_text != file_contents.text {
             write_file_contents(
@@ -293,14 +344,18 @@ async fn format_source_files(paths: Vec<PathBuf>) -> Result<(), AnyError> {
 /// Format stdin and write result to stdout.
 /// Treats input as TypeScript or as set by `--ext` flag.
 /// Compatible with `--check` flag.
-pub fn format_stdin(check: bool, ext: String) -> Result<(), AnyError> {
+pub fn format_stdin(
+  check: bool,
+  ext: String,
+  fmt_options: FmtOptionsConfig,
+) -> Result<(), AnyError> {
   let mut source = String::new();
   if stdin().read_to_string(&mut source).is_err() {
     return Err(generic_error("Failed to read from stdin"));
   }
   let file_path = PathBuf::from(format!("_stdin.{}", ext));
 
-  match format_file(&file_path, &source) {
+  match format_file(&file_path, &source, fmt_options) {
     Ok(formatted_text) => {
       if check {
         if formatted_text != source {
@@ -325,18 +380,86 @@ fn files_str(len: usize) -> &'static str {
   }
 }
 
-lazy_static::lazy_static! {
-  static ref TYPESCRIPT_CONFIG: dprint_plugin_typescript::configuration::Configuration = dprint_plugin_typescript::configuration::ConfigurationBuilder::new()
-    .deno()
-    .build();
+fn get_resolved_typescript_config(
+  options: &FmtOptionsConfig,
+) -> dprint_plugin_typescript::configuration::Configuration {
+  let mut builder =
+    dprint_plugin_typescript::configuration::ConfigurationBuilder::new();
+  builder.deno();
+
+  if let Some(use_tabs) = options.use_tabs {
+    builder.use_tabs(use_tabs);
+  }
 
-  static ref MARKDOWN_CONFIG: dprint_plugin_markdown::configuration::Configuration = dprint_plugin_markdown::configuration::ConfigurationBuilder::new()
-    .deno()
-    .build();
+  if let Some(line_width) = options.line_width {
+    builder.line_width(line_width);
+  }
+
+  if let Some(indent_width) = options.indent_width {
+    builder.indent_width(indent_width);
+  }
+
+  if let Some(single_quote) = options.single_quote {
+    if single_quote {
+      builder.quote_style(
+        dprint_plugin_typescript::configuration::QuoteStyle::AlwaysSingle,
+      );
+    }
+  }
+
+  builder.build()
+}
+
+fn get_resolved_markdown_config(
+  options: &FmtOptionsConfig,
+) -> dprint_plugin_markdown::configuration::Configuration {
+  let mut builder =
+    dprint_plugin_markdown::configuration::ConfigurationBuilder::new();
+
+  builder.deno();
+
+  if let Some(line_width) = options.line_width {
+    builder.line_width(line_width);
+  }
+
+  if let Some(prose_wrap) = options.prose_wrap {
+    builder.text_wrap(match prose_wrap {
+      ProseWrap::Always => {
+        dprint_plugin_markdown::configuration::TextWrap::Always
+      }
+      ProseWrap::Never => {
+        dprint_plugin_markdown::configuration::TextWrap::Never
+      }
+      ProseWrap::Preserve => {
+        dprint_plugin_markdown::configuration::TextWrap::Maintain
+      }
+    });
+  }
+
+  builder.build()
+}
+
+fn get_resolved_json_config(
+  options: &FmtOptionsConfig,
+) -> dprint_plugin_json::configuration::Configuration {
+  let mut builder =
+    dprint_plugin_json::configuration::ConfigurationBuilder::new();
+
+  builder.deno();
+
+  if let Some(use_tabs) = options.use_tabs {
+    builder.use_tabs(use_tabs);
+  }
+
+  if let Some(line_width) = options.line_width {
+    builder.line_width(line_width);
+  }
+
+  if let Some(indent_width) = options.indent_width {
+    builder.indent_width(indent_width);
+  }
 
-  static ref JSON_CONFIG: dprint_plugin_json::configuration::Configuration = dprint_plugin_json::configuration::ConfigurationBuilder::new()
-    .deno()
-    .build();
+  builder.build()
 }
 
 struct FileContents {