add solution to exercise 4.3

Author: bboydflo

04-asynchronous-control-flow-patterns-with-callbacks/4.3-recursive-find.js

@@ -0,0 +1,77 @@
+import fs from 'fs'
+import path from 'path'
+
+const onError = err => console.error(err)
+
+const checkKeywordInFile = (filePath, keyword, matchesCallback) => {
+    fs.readFile(filePath, 'utf-8', (fileReadErr, fileContent) => {
+        if (fileReadErr) {
+            return matchesCallback(fileReadErr)
+        }
+        if (!fileContent) {
+            return matchesCallback(null, false)
+        }
+        /* const resp = fileContent.split('\n').filter(line => line.includes(keyword))
+        if (!resp.length) {
+            return matchesCallback(null, false)
+        }
+        matchesCallback(null, true) */
+
+        return matchesCallback(null, fileContent.includes(keyword))
+    })
+}
+
+const findFileMatches = (dir, keyword, matches, cb) => {
+    fs.readdir(dir, { withFileTypes: true }, (readDirErr, files) => {
+        if (readDirErr) {
+            return cb(readDirErr)
+        }
+
+        let completed = 0
+
+        const { dirFiles, subDirs } = files.reduce((acc, curr) => {
+            acc[curr.isFile() ? 'dirFiles' : 'subDirs'].push(curr)
+            return acc
+        }, { dirFiles: [], subDirs: [] })
+
+        function iterate(index) {
+            if (index === subDirs.length) {
+                return cb(null, matches)
+            }
+
+            const newDirPath = path.join(dir, subDirs[index].name)
+            findFileMatches(newDirPath, keyword, matches, () => {
+                iterate(index + 1)
+            })
+        }
+
+        function doneCheck() {
+            // when finished searching for a match in the current files continue with the next directory
+            if (++completed === dirFiles.length) {
+                return iterate(0)
+            }
+        }
+
+        dirFiles.forEach(file => {
+            const filePath = path.join(dir, file.name)
+
+            checkKeywordInFile(filePath, keyword, (_, matching) => {
+                if (matching) {
+                    matches.push(filePath)
+                }
+                doneCheck()
+            })
+        })
+    })
+}
+
+const recursiveFind = (dirPath, keyword, finalCallback) => {
+    findFileMatches(dirPath, keyword, [], (err, matches) => {
+        if (err) {
+            return onError(err)
+        }
+        finalCallback(matches)
+    })
+}
+
+recursiveFind('./filesToConcat', 'batman', console.log)