feat: Implement filter strategies

Author: OleRoss

README.md

@@ -34,15 +34,18 @@ jobs:
             coverage/coverage1.xml
             coverage/coverage2.xml
           update-comment: true
+          show-changed-lines-only: true
+          show-glob-only: '**/**'
 ```
 
 ### Inputs
 
-| Name             | Default    | Description                                                     |
-|------------------|------------|-----------------------------------------------------------------|
-| `files`          | (required) | One or multiple files. Can be multiple lines. Glob is supported |
-| `update-comment` | true       | Visualize for changed lines only                                |
-| `path-glob`      | true       | Select subdirectories to show coverage data for                 |
+| Name                      | Default    | Description                                                     |
+|---------------------------|------------|-----------------------------------------------------------------|
+| `files`                   | (required) | One or multiple files. Can be multiple lines. Glob is supported |
+| `update-comment`          | true       | TODO: Update                                                    |
+| `show-changed-lines-only` | true       | If part of a PR, filter coverage data against changed lines     |
+| `show-glob-only`          | '**'    | Select subdirectories to show coverage data for                 |
 
 ### Outputs
 

action.yaml

@@ -9,10 +9,14 @@ inputs:
     description: Whether to update an existing comment instead of creating a new one
     required: false
     default: 'true'
-  path-glob:
+  show-changed-lines-only:
+    description: If part of a PR, filter coverage data against changed lines
+    required: false
+    default: 'true'
+  show-glob-only:
     description: Select subdirectories to show coverage data for
     required: false
-    default: ''
+    default: '**'
   token:
     description: GitHub token for API access
     required: true

package.json

@@ -12,19 +12,21 @@
     "@octokit/action": "8.0.4",
     "@octokit/plugin-retry": "8.0.3",
     "fast-xml-parser": "^5.3.3",
-    "glob": "^11.0.0"
+    "glob": "^11.0.0",
+    "minimatch": "^10.1.1"
   },
   "devDependencies": {
     "@biomejs/biome": "2.3.10",
     "@octokit/webhooks-types": "7.6.1",
     "@tsconfig/node20": "20.1.8",
     "@tsconfig/strictest": "2.0.8",
+    "@types/minimatch": "^6.0.0",
     "@types/node": "20.19.27",
     "@vercel/ncc": "0.38.4",
+    "@vitest/coverage-v8": "4.0.16",
     "pnpm": "10.26.1",
     "typescript": "5.9.3",
-    "vitest": "4.0.16",
-    "@vitest/coverage-v8": "4.0.16"
+    "vitest": "4.0.16"
   },
   "engines": {
     "node": "20.x"

pnpm-lock.yaml

@@ -0,0 +1,166 @@
+import { exec } from 'node:child_process'
+import { promisify } from 'node:util'
+import type { ChangedLinesMap } from './model.js'
+
+const execAsync = promisify(exec)
+
+/**
+ * Get changed lines by comparing against a base ref using local git.
+ * Requires the repository to be checked out.
+ *
+ * @param baseRef - The base ref to compare against (e.g., 'origin/main', commit SHA)
+ * @returns Map of filename to set of changed line numbers
+ */
+export async function getChangedLinesFromGit(baseRef: string): Promise<ChangedLinesMap> {
+  // Get the unified diff between base ref and HEAD
+  const { stdout: diffOutput } = await execAsync(`git diff ${baseRef}...HEAD`, {
+    maxBuffer: 10 * 1024 * 1024, // 10MB buffer for large diffs
+  })
+
+  return parseDiffOutput(diffOutput)
+}
+
+/**
+ * Parse full git diff output to extract changed lines per file.
+ *
+ * @param diffOutput - Full git diff output
+ * @returns Map of filename to set of changed line numbers
+ */
+export function parseDiffOutput(diffOutput: string): ChangedLinesMap {
+  const changedLines: ChangedLinesMap = new Map()
+  const lines = diffOutput.split('\n')
+
+  let currentFile: string | null = null
+
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i]!
+
+    // Parse diff header: diff --git a/path/to/file b/path/to/file
+    const diffMatch = line.match(/^diff --git a\/.+ b\/(.+)$/)
+    if (diffMatch) {
+      currentFile = diffMatch[1]!
+      continue
+    }
+
+    // Skip deleted files (indicated by /dev/null in new file)
+    if (line.startsWith('+++ /dev/null')) {
+      currentFile = null
+      continue
+    }
+
+    // Skip if we don't have a current file
+    if (!currentFile) {
+      continue
+    }
+
+    // Parse hunk and extract changed lines
+    const hunkMatch = line.match(/^@@ -\d+(?:,\d+)? \+(\d+)(?:,\d+)? @@/)
+    if (hunkMatch) {
+      const startLine = Number.parseInt(hunkMatch[1]!, 10)
+      const hunkChangedLines = parseHunkForChangedLines(lines, i, startLine)
+
+      // Merge with existing changed lines for this file
+      const existing = changedLines.get(currentFile) ?? new Set<number>()
+      for (const lineNum of hunkChangedLines) {
+        existing.add(lineNum)
+      }
+      changedLines.set(currentFile, existing)
+    }
+  }
+
+  return changedLines
+}
+
+/**
+ * Parse a single hunk starting from a given index to extract changed line numbers.
+ *
+ * @param lines - All lines of the diff
+ * @param hunkStartIndex - Index of the hunk header line
+ * @param startLine - Starting line number from the hunk header
+ * @returns Set of changed line numbers in this hunk
+ */
+function parseHunkForChangedLines(lines: string[], hunkStartIndex: number, startLine: number): Set<number> {
+  const changedLines = new Set<number>()
+  let currentLine = startLine
+
+  // Start after the hunk header
+  for (let i = hunkStartIndex + 1; i < lines.length; i++) {
+    const line = lines[i]!
+
+    // Stop at next hunk or diff header
+    if (line.startsWith('@@') || line.startsWith('diff --git')) {
+      break
+    }
+
+    // Lines starting with '-' are removed lines (don't exist in new file)
+    if (line.startsWith('-')) {
+      // Don't increment currentLine for removed lines
+      continue
+    }
+
+    // Lines starting with '+' are added lines
+    if (line.startsWith('+')) {
+      changedLines.add(currentLine)
+      currentLine++
+      continue
+    }
+
+    // Context lines (starting with space or no prefix) exist in both versions
+    currentLine++
+  }
+
+  return changedLines
+}
+
+/**
+ * Parse a unified diff patch to extract added/modified line numbers.
+ *
+ * The patch format uses @@ -old_start,old_count +new_start,new_count @@ headers
+ * followed by context lines (starting with space), removed lines (starting with -)
+ * and added lines (starting with +).
+ *
+ * We only care about added lines (lines starting with +) as those are the
+ * "new" lines that exist in the PR's version of the file.
+ *
+ * @param patch - Unified diff patch string
+ * @returns Set of line numbers that were added/modified
+ */
+export function parsePatchForChangedLines(patch: string): Set<number> {
+  const changedLines = new Set<number>()
+  const lines = patch.split('\n')
+
+  let currentLine = 0
+
+  for (const line of lines) {
+    // Parse hunk header: @@ -old_start,old_count +new_start,new_count @@
+    const hunkMatch = line.match(/^@@ -\d+(?:,\d+)? \+(\d+)(?:,\d+)? @@/)
+    if (hunkMatch) {
+      currentLine = Number.parseInt(hunkMatch[1]!, 10)
+      continue
+    }
+
+    // Skip if we haven't seen a hunk header yet
+    if (currentLine === 0) {
+      continue
+    }
+
+    // Lines starting with '-' are removed lines (don't exist in new file)
+    if (line.startsWith('-')) {
+      // Don't increment currentLine for removed lines
+      continue
+    }
+
+    // Lines starting with '+' are added lines
+    if (line.startsWith('+')) {
+      changedLines.add(currentLine)
+      currentLine++
+      continue
+    }
+
+    // Context lines (starting with space or no prefix) exist in both versions
+    // We don't add them to changed lines, but we do increment the line counter
+    currentLine++
+  }
+
+  return changedLines
+}