feat(*): add line endings rule, add automatic formatting for fixable violations

src/rules/file/lineEndings.ts

@@ -0,0 +1,83 @@
+import { Diagnostic, LintConfig } from '../../types'
+import { LineEndings } from '../../types/LineEndings'
+import { FileLintRule } from '../../types/LintRule'
+import { LintRuleType } from '../../types/LintRuleType'
+import { Severity } from '../../types/Severity'
+
+const name = 'lineEndings'
+const description = 'Ensures line endings conform to the configured type.'
+const message = 'Incorrect line ending - {actual} instead of {expected}'
+const test = (value: string, config?: LintConfig) => {
+  const lineEndingConfig = config?.lineEndings || LineEndings.LF
+  const expectedLineEnding =
+    lineEndingConfig === LineEndings.LF ? '{lf}' : '{crlf}'
+  const incorrectLineEnding = expectedLineEnding === '{lf}' ? '{crlf}' : '{lf}'
+
+  const lines = value
+    .replace(/\r\n/g, '{crlf}')
+    .replace(/\n/g, '{lf}')
+    .split(new RegExp(`(?<=${expectedLineEnding})`))
+  const diagnostics: Diagnostic[] = []
+
+  let indexOffset = 0
+  lines.forEach((line, index) => {
+    if (line.endsWith(incorrectLineEnding)) {
+      diagnostics.push({
+        message: message
+          .replace('{expected}', expectedLineEnding === '{lf}' ? 'LF' : 'CRLF')
+          .replace('{actual}', incorrectLineEnding === '{lf}' ? 'LF' : 'CRLF'),
+        lineNumber: index + 1 + indexOffset,
+        startColumnNumber: line.indexOf(incorrectLineEnding),
+        endColumnNumber: line.indexOf(incorrectLineEnding) + 1,
+        severity: Severity.Warning
+      })
+    } else {
+      const splitLine = line.split(new RegExp(`(?<=${incorrectLineEnding})`))
+      if (splitLine.length > 1) {
+        indexOffset += splitLine.length - 1
+      }
+      splitLine.forEach((l, i) => {
+        if (l.endsWith(incorrectLineEnding)) {
+          diagnostics.push({
+            message: message
+              .replace(
+                '{expected}',
+                expectedLineEnding === '{lf}' ? 'LF' : 'CRLF'
+              )
+              .replace(
+                '{actual}',
+                incorrectLineEnding === '{lf}' ? 'LF' : 'CRLF'
+              ),
+            lineNumber: index + i + 1,
+            startColumnNumber: l.indexOf(incorrectLineEnding),
+            endColumnNumber: l.indexOf(incorrectLineEnding) + 1,
+            severity: Severity.Warning
+          })
+        }
+      })
+    }
+  })
+  return diagnostics
+}
+
+const fix = (value: string, config?: LintConfig): string => {
+  const lineEndingConfig = config?.lineEndings || LineEndings.LF
+
+  return value
+    .replace(/\r\n/g, '{crlf}')
+    .replace(/\n/g, '{lf}')
+    .replace(/{crlf}/g, lineEndingConfig === LineEndings.LF ? '\n' : '\r\n')
+    .replace(/{lf}/g, lineEndingConfig === LineEndings.LF ? '\n' : '\r\n')
+}
+
+/**
+ * Lint rule that checks if line endings in a file match the configured type.
+ */
+export const lineEndings: FileLintRule = {
+  type: LintRuleType.File,
+  name,
+  description,
+  message,
+  test,
+  fix
+}