package healthcheck

import (
	"bufio"
	"fmt"
	"os"
	"path/filepath"
)

// fileExists checks if a file exists at the specified path.
func fileExists(filePath string) bool {
	_, err := os.Stat(filePath)
	return !os.IsNotExist(err)
}

// filesMatch checks if two files are identical.
func filesMatch(file1, file2 string) (bool, error) {
	f1, err := os.Open(file1)
	if err != nil {
		return false, err
	}
	defer f1.Close()

	f2, err := os.Open(file2)
	if err != nil {
		return false, err
	}
	defer f2.Close()

	scanner1 := bufio.NewScanner(f1)
	scanner2 := bufio.NewScanner(f2)

	for scanner1.Scan() && scanner2.Scan() {
		line1 := scanner1.Text()
		line2 := scanner2.Text()

		if line1 != line2 {
			return false, nil
		}
	}

	if scanner1.Scan() || scanner2.Scan() {
		// One file has more lines than the other
		return false, nil
	}

	return true, nil
}

// compareDirectories compares the contents of two directories.
func compareDirectories(dir1, dir2 string, jsonOut *CheckStage) error {
	allMatch := true
	var message string
	err := filepath.Walk(dir1, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		if !info.IsDir() {
			relPath, _ := filepath.Rel(dir1, path)
			file2 := filepath.Join(dir2, relPath)

			if !fileExists(file2) {
				// fmt.Printf("File %s in %s is missing in %s\n, please immediately revert your changes!\n", relPath, dir1, dir2)
				message += "File missing"
				allMatch = false
				jsonOut.StdOut += "Failed"
				jsonOut.ExitCode = 101
				jsonOut.StdErr = message
				return nil
			}

			// fmt.Printf("Checking integrity of %s:\n", path)
			match, err := filesMatch(path, file2)
			if err != nil {
				return err
			}

			if !match {
				// fmt.Printf("File %s in %s is not identical to %s\nPlease revert your changes or contact the teaching team if you have a valid reason for adjusting them.\n", relPath, dir1, dir2)
				message += "File is not identical"
				allMatch = false
				jsonOut.StdOut += "Failed"
				jsonOut.ExitCode = 101
				jsonOut.StdErr = message
			}
		}
		return nil
	})

	if allMatch {
		jsonOut.StdOut += "OK!"
	} else {
		jsonOut.StdOut += "Failed!"
	}

	return err
}

// Verify checks if the contents of two directories are identical.
func Verify(rootDir, compareDir string) CheckStage {
	jsonOut := CheckStage{
		Name:     "verifyFile",
		StdOut:   "Checking files to be verified: ",
		ExitCode: 0,
		StdErr:   "",
	}
	err := compareDirectories(rootDir, compareDir, &jsonOut)
	// fmt.Println("Comparison finished ")
	if err != nil {
		fmt.Println("Error:", err)
	}
	return jsonOut
}