DRAFT: add fix command line option and fix --check

src/FSharpLint.Console/Program.fs

@@ -2,8 +2,11 @@
 
 open Argu
 open System
+open System.IO
+open System.Text
 open FSharpLint.Framework
 open FSharpLint.Application
+open System.Linq
 
 /// Output format the linter will use.
 type private OutputFormat =
@@ -17,17 +20,31 @@ type private FileType =
     | File = 3
     | Source = 4
 
+type ExitCode = 
+    | Error = -1
+    // for `fix` when the file is changed and for `fix --check` when there are no fixes available.
+    | Success = 0 
+    | NoSuchRuleName = 1
+    // only for fix (without --check)
+    | NoSuggestedFix = 2
+    //only for fix --check
+    | FixExists = 3 
+
+let fileTypeHelp = "Input type the linter will run against. If this is not set, the file type will be inferred from the file extension."
+
 // Allowing underscores in union case names for proper Argu command line option formatting.
 // fsharplint:disable UnionCasesNames
 type private ToolArgs =
     | [<AltCommandLine("-f")>] Format of OutputFormat
     | [<CliPrefix(CliPrefix.None)>] Lint of ParseResults<LintArgs>
+    | [<CliPrefix(CliPrefix.None)>] Fix of ParseResults<FixArgs>
 with
     interface IArgParserTemplate with
         member this.Usage =
             match this with
             | Format _ -> "Output format of the linter."
             | Lint _ -> "Runs FSharpLint against a file or a collection of files."
+            | Fix _ -> "Apply quickfixes for specified rule name or names (comma separated)."
 
 // TODO: investigate erroneous warning on this type definition
 // fsharplint:disable UnionDefinitionIndentation
@@ -41,10 +58,26 @@ with
         member this.Usage =
             match this with
             | Target _ -> "Input to lint."
-            | File_Type _ -> "Input type the linter will run against. If this is not set, the file type will be inferred from the file extension."
+            | File_Type _ -> fileTypeHelp
             | Lint_Config _ -> "Path to the config for the lint."
 // fsharplint:enable UnionCasesNames
 
+// TODO: investigate erroneous warning on this type definition
+// fsharplint:disable UnionDefinitionIndentation
+and private FixArgs =
+    | [<MainCommand; Mandatory>] Fix_Target of ruleName:string * target:string
+    | Fix_File_Type of FileType
+    | Check
+// fsharplint:enable UnionDefinitionIndentation
+with
+    interface IArgParserTemplate with
+        member this.Usage =
+            match this with
+            | Fix_Target _ -> "Rule name to be applied with suggestedFix and input to lint."
+            | Fix_File_Type _ -> fileTypeHelp
+            | Check _ -> "If passed to the fix command, the linter will only check if the fix is needed."
+// fsharplint:enable UnionCasesNames
+
 let private parserProgress (output:Output.IOutput) = function
     | Starting file ->
         String.Format(Resources.GetString("ConsoleStartingFile"), file) |> output.WriteInfo
@@ -70,7 +103,7 @@ let private inferFileType (target:string) =
         FileType.Source
 
 let private start (arguments:ParseResults<ToolArgs>) (toolsPath:Ionide.ProjInfo.Types.ToolsPath) =
-    let mutable exitCode = 0
+    let mutable exitCode = ExitCode.Success
 
     let output =
         match arguments.TryGetResult Format with
@@ -79,38 +112,79 @@ let private start (arguments:ParseResults<ToolArgs>) (toolsPath:Ionide.ProjInfo.
         | Some _
         | None -> Output.StandardOutput() :> Output.IOutput
 
-    let handleError (str:string) =
+    let handleError (status: ExitCode) (str: string) =
         output.WriteError str
-        exitCode <- -1
-
-    match arguments.GetSubCommand() with
-    | Lint lintArgs ->
-
-        let handleLintResult = function
-            | LintResult.Success(warnings) ->
-                String.Format(Resources.GetString("ConsoleFinished"), List.length warnings)
-                |> output.WriteInfo
-                if not (List.isEmpty warnings) then exitCode <- -1
-            | LintResult.Failure(failure) ->
-                handleError failure.Description
-
-        let lintConfig = lintArgs.TryGetResult Lint_Config
-
-        let configParam =
-            match lintConfig with
-            | Some configPath -> FromFile configPath
-            | None -> Default
-
+        exitCode <- status
 
-        let lintParams =
-            { CancellationToken = None
-              ReceivedWarning = Some output.WriteWarning
-              Configuration = configParam
-              ReportLinterProgress = Some (parserProgress output) }
+    let outputWarnings (warnings: List<Suggestion.LintWarning>) =
+        String.Format(Resources.GetString "ConsoleFinished", List.length warnings)
+            |> output.WriteInfo
+
+    let handleLintResult = function
+        | LintResult.Success warnings ->
+            outputWarnings warnings
+            if List.isEmpty warnings |> not then 
+               exitCode <- ExitCode.Error
+        | LintResult.Failure failure -> handleError ExitCode.Error failure.Description
+
+    let handleFixResult (ruleName: string) (checkFlag: bool) = function
+        | LintResult.Success warnings ->
+            if not checkFlag then
+                Resources.GetString "ConsoleApplyingSuggestedFixFile" |> output.WriteInfo
+            let noFixIncrement = 0
+            let foundFixIncrement = 1
+            let noSuggestedFixIncrement = 2
+            let countFixStatus = 
+                List.fold (fun (accNoFix, accFoundFix, accNoSuggestedFix) elem -> 
+                    if elem = noFixIncrement then
+                        (accNoFix + 1, accFoundFix, accNoSuggestedFix)
+                    elif elem = foundFixIncrement then
+                        (accNoFix, accFoundFix + 1, accNoSuggestedFix)
+                    elif elem = noSuggestedFixIncrement then
+                        (accNoFix, accFoundFix, accNoSuggestedFix + 1)
+                    else
+                        failwith "Code should never reach here!") (0, 0, 0) (
+                    List.map (fun (element: Suggestion.LintWarning) ->
+                        let sourceCode = File.ReadAllText element.FilePath
+                        if String.Equals(ruleName, element.RuleName, StringComparison.InvariantCultureIgnoreCase) then
+                            match element.Details.SuggestedFix with
+                            | Some suggestedFix ->
+                                ((fun checkFlag ->
+                                if not checkFlag then
+                                    (suggestedFix.Force()
+                                    |> Option.map (fun suggestedFix ->
+                                        let updatedSourceCode = 
+                                            sourceCode.Replace(
+                                                suggestedFix.FromText,
+                                                suggestedFix.ToText
+                                            )
+                                        File.WriteAllText(
+                                            element.FilePath,
+                                            updatedSourceCode,
+                                            Encoding.UTF8)
+                                        )
+                                    ) |> ignore
+                                else
+                                    ()
+                                ) checkFlag)
+                                |> ignore |> fun () -> foundFixIncrement
+                            | None -> noSuggestedFixIncrement
+                        else
+                            noFixIncrement) warnings)
+            outputWarnings warnings
+            let (accNoFix, accFoundFix, accNoSuggestedFix) = countFixStatus
+            if not checkFlag && accFoundFix > 0 then
+                exitCode <- ExitCode.Success
+            elif not checkFlag then
+                exitCode <- ExitCode.NoSuggestedFix
+            elif checkFlag && accFoundFix > 0 then
+                exitCode <- ExitCode.FixExists
+            elif checkFlag then
+                exitCode <- ExitCode.Success
 
-        let target = lintArgs.GetResult Target
-        let fileType = lintArgs.TryGetResult File_Type |> Option.defaultValue (inferFileType target)
+        | LintResult.Failure failure -> handleError ExitCode.Error failure.Description
 
+    let linting fileType lintParams target toolsPath shouldFix maybeRuleName checkFlag =
         try
             let lintResult =
                 match fileType with
@@ -119,15 +193,70 @@ let private start (arguments:ParseResults<ToolArgs>) (toolsPath:Ionide.ProjInfo.
                 | FileType.Solution -> Lint.lintSolution lintParams target toolsPath
                 | FileType.Project
                 | _ -> Lint.lintProject lintParams target toolsPath
-            handleLintResult lintResult
+            if shouldFix then
+                match maybeRuleName with
+                | Some ruleName -> handleFixResult ruleName checkFlag lintResult
+                | None -> exitCode <- ExitCode.NoSuchRuleName
+            else
+                handleLintResult lintResult
         with
         | e ->
             let target = if fileType = FileType.Source then "source" else target
             sprintf "Lint failed while analysing %s.\nFailed with: %s\nStack trace: %s" target e.Message e.StackTrace
-            |> handleError
+            |> (handleError ExitCode.Error)
+
+    let getParams config =
+        let paramConfig =
+            match config with
+            | Some configPath -> FromFile configPath
+            | None -> Default
+
+        { CancellationToken = None
+          ReceivedWarning = Some output.WriteWarning
+          Configuration = paramConfig
+          ReportLinterProgress = parserProgress output |> Some }
+
+    let applyLint (lintArgs: ParseResults<LintArgs>) =
+        let lintConfig = lintArgs.TryGetResult Lint_Config
+
+        let lintParams = getParams lintConfig
+        let target = lintArgs.GetResult Target
+        let fileType = lintArgs.TryGetResult File_Type |> Option.defaultValue (inferFileType target)
+
+        linting fileType lintParams target toolsPath false None false
+
+    let applySuggestedFix (fixArgs: ParseResults<FixArgs>) =
+        let fixParams = getParams None
+        let ruleName, target = fixArgs.GetResult Fix_Target
+        let fileType = fixArgs.TryGetResult Fix_File_Type |> Option.defaultValue (inferFileType target)
+        let checkFlag = fixArgs.Contains Check
+
+        let allRules = 
+            match getConfig fixParams.Configuration with
+            | Ok config -> Some (Configuration.flattenConfig config false)
+            | _ -> None
+
+        let allRuleNames =
+            match allRules with
+            | Some rules ->  (fun (loadedRules:Configuration.LoadedRules) -> ([|
+                loadedRules.LineRules.IndentationRule |> Option.map (fun rule -> rule.Name) |> Option.toArray
+                loadedRules.LineRules.NoTabCharactersRule |> Option.map (fun rule -> rule.Name) |> Option.toArray
+                loadedRules.LineRules.GenericLineRules |> Array.map (fun rule -> rule.Name)
+                loadedRules.AstNodeRules |> Array.map (fun rule -> rule.Name)
+                |] |> Array.concat |> Set.ofArray)) rules
+            | _ -> Set.empty
+
+        if allRuleNames.Any(fun aRuleName -> String.Equals(aRuleName, ruleName, StringComparison.InvariantCultureIgnoreCase)) then
+            linting fileType fixParams target toolsPath true (Some ruleName) checkFlag
+        else
+            sprintf "Rule '%s' does not exist." ruleName |> (handleError ExitCode.NoSuchRuleName)
+
+    match arguments.GetSubCommand() with
+    | Lint lintArgs -> applyLint lintArgs
+    | Fix fixArgs -> applySuggestedFix fixArgs
     | _ -> ()
 
-    exitCode
+    int exitCode
 
 /// Must be called only once per process.
 /// We're calling it globally so we can call main multiple times from our tests.

src/FSharpLint.Core/Application/Configuration.fs

@@ -129,13 +129,20 @@ type RuleConfig<'Config> = {
 
 type EnabledConfig = RuleConfig<unit>
 
-let constructRuleIfEnabled rule ruleConfig = if ruleConfig.Enabled then Some rule else None
+let constructRuleIfEnabledBase (onlyEnabled: bool) rule ruleConfig = 
+    if not onlyEnabled || ruleConfig.Enabled then Some rule else None
 
-let constructRuleWithConfig rule ruleConfig =
-    if ruleConfig.Enabled then
-        ruleConfig.Config |> Option.map rule
-    else
-        None
+let constructRuleIfEnabled rule ruleConfig = 
+    constructRuleIfEnabledBase true rule ruleConfig
+
+let constructRuleWithConfigBase (onlyEnabled: bool) (rule: 'TRuleConfig -> 'TRule) (ruleConfig: RuleConfig<'TRuleConfig>): Option<'TRule> =
+     if not onlyEnabled || ruleConfig.Enabled then
+         ruleConfig.Config |> Option.map rule
+     else
+         None
+
+let constructRuleWithConfig (rule: 'TRuleConfig -> 'TRule) (ruleConfig: RuleConfig<'TRuleConfig>): Option<'TRule> =
+    constructRuleWithConfigBase true rule ruleConfig
 
 type TupleFormattingConfig =
     { tupleCommaSpacing:EnabledConfig option
@@ -600,7 +607,7 @@ let private parseHints (hints:string []) =
     |> Array.toList
     |> MergeSyntaxTrees.mergeHints
 
-let flattenConfig (config:Configuration) =
+let flattenConfig (config:Configuration) (onlyEnabled:bool) =
     let deprecatedAllRules =
         [|
             config.formatting |> Option.map (fun config -> config.Flatten()) |> Option.toArray |> Array.concat
@@ -609,6 +616,12 @@ let flattenConfig (config:Configuration) =
             config.Hints |> Option.map (fun config -> HintMatcher.rule { HintMatcher.Config.HintTrie = parseHints (getOrEmptyList config.add) }) |> Option.toArray
         |] |> Array.concat
 
+    let constructRuleIfEnabled rule ruleConfig = 
+        constructRuleIfEnabledBase onlyEnabled rule ruleConfig
+
+    let constructRuleWithConfig (rule: 'TRuleConfig -> 'TRule) (ruleConfig: RuleConfig<'TRuleConfig>): Option<'TRule> =
+        constructRuleWithConfigBase onlyEnabled rule ruleConfig
+
     let allRules =
         [|
             config.TypedItemSpacing |> Option.bind (constructRuleWithConfig TypedItemSpacing.rule)

src/FSharpLint.Core/Application/Lint.fs

@@ -206,7 +206,7 @@ module Lint =
             | Some(x) -> not x.IsCancellationRequested
             | None -> true
 
-        let enabledRules = Configuration.flattenConfig lintInfo.Configuration
+        let enabledRules = Configuration.flattenConfig lintInfo.Configuration true
 
         let lines = String.toLines fileInfo.Text |> Array.map (fun (line, _, _) -> line)
         let allRuleNames =
@@ -371,7 +371,7 @@ module Lint =
     }
 
     /// Gets a FSharpLint Configuration based on the provided ConfigurationParam.
-    let private getConfig (configParam:ConfigurationParam) =
+    let getConfig (configParam:ConfigurationParam) =
         match configParam with
         | Configuration config -> Ok config
         | FromFile filePath ->

src/FSharpLint.Core/Application/Lint.fsi

@@ -144,4 +144,6 @@ module Lint =
 
     /// Lints an F# file that has already been parsed using
     /// `FSharp.Compiler.Services` in the calling application.
-    val lintParsedFile : optionalParams:OptionalLintParameters -> parsedFileInfo:ParsedFileInformation -> filePath:string -> LintResult
+    val lintParsedFile : optionalParams:OptionalLintParameters -> parsedFileInfo:ParsedFileInformation -> filePath:string -> LintResult
+
+    val getConfig : ConfigurationParam -> Result<Configuration,string>

src/FSharpLint.Core/Text.resx

@@ -138,6 +138,9 @@
   <data name="ConsoleStartingFile" xml:space="preserve">
     <value>========== Linting {0} ==========</value>
   </data>
+  <data name="ConsoleApplyingSuggestedFixFile" xml:space="preserve">
+    <value>========== Applying fixes ==========</value>
+  </data>
   <data name="ConsoleMSBuildFailedToLoadProjectFile" xml:space="preserve">
     <value>MSBuild could not load the project file {0} because: {1}</value>
   </data>