zephinzer/dev

package filesystem

import (
    "fmt"
    "io/ioutil"
    "os"
    "path"
    "path/filepath"
    "strings"
)

// FindParentContainingChildDirectory continously ascends from the initial
// directory path at `startingFrom` and checks for the existence of a child
// directory named `targetDirectoryName` for `levels[0]` levels.
//
// On successfully finding such a child directory, it returns the path of the
// parent directory as the first argument, on failing to find, it returns an
// empty string. In both cases, the returned `error`-typed argument will be nil.
//
// If the function failed to complete, the second `error`-typed argument will
// be non-nil.
func FindParentContainingChildDirectory(targetDirectoryName, startingFrom string, levels ...int) (string, error) {
    // resolve to absolute if not already
    directoryPath := startingFrom
    if !path.IsAbs(startingFrom) {
        cwd, getCwdError := os.Getwd()
        if getCwdError != nil {
            return "", fmt.Errorf("failed to retrieve working directory: %s", getCwdError)
        }
        directoryPath = path.Join(cwd, startingFrom)
    }

    // prepare number of directories to ascend to
    searchDepth := -1
    if len(levels) > 0 {
        searchDepth = levels[0]
    }

    // descend into the depths and search one by one
    splitPath := strings.Split(directoryPath, string(filepath.Separator))
    for len(splitPath) >= 2 && searchDepth != 0 {
        fileListing, readDirError := ioutil.ReadDir(directoryPath)
        if readDirError != nil {
            return "", fmt.Errorf("failed to read directory at '%s': %s", directoryPath, readDirError)
        }
        for _, file := range fileListing {
            if file.IsDir() && file.Name() == targetDirectoryName {
                return directoryPath, nil
            }
        }
        directoryPath = path.Dir(directoryPath)
        splitPath = strings.Split(directoryPath, string(filepath.Separator))
        if directoryPath == "/" {
            break
        }
        searchDepth--
    }

    return "", nil
}