package sync

import (
	"encoding/hex"
	"fmt"
	"path"
	"strings"
	"unicode"

	"srs.epita.fr/fic-server/libfic"
)

// SyncExerciceFiles reads the content of files/ directory and import it as EFile for the given challenge.
// It takes care of DIGESTS.txt and ensure imported files match.
func SyncExerciceFiles(i Importer, exercice fic.Exercice) (errs []string) {
	// If no files directory, don't display error
	if ! i.exists(path.Join(exercice.Path, "files")) {
		return
	}

	if digs, err := getFileContent(i, path.Join(exercice.Path, "files", "DIGESTS.txt")); err != nil {
		errs = append(errs, fmt.Sprintf("%q: unable to read DIGESTS.txt: %s", path.Base(exercice.Path), err))
	} else if _, err := exercice.WipeFiles(); err != nil {
		errs = append(errs, err.Error())
	} else if files, err := i.listDir(path.Join(exercice.Path, "files")); err != nil {
		errs = append(errs, err.Error())
	} else {
		// Parse DIGESTS.txt
		digests := map[string][]byte{}
		for nline, d := range strings.Split(digs, "\n") {
			if dsplt := strings.SplitN(d, " ", 2); len(dsplt) != 2 {
				errs = append(errs, fmt.Sprintf("%q: unable to parse DIGESTS.txt line %d: invalid format", path.Base(exercice.Path), nline + 1))
				continue
			} else if hash, err := hex.DecodeString(dsplt[0]); err != nil {
				errs = append(errs, fmt.Sprintf("%q: unable to parse DIGESTS.txt line %d: %s", path.Base(exercice.Path), nline + 1, err))
				continue
			} else {
				digests[strings.TrimLeftFunc(dsplt[1], unicode.IsSpace)] = hash
			}
		}

		// Import splitted files
		var splittedFiles []string
		for _, fname := range files {
			if matched, _ := path.Match("*.00", fname); matched {
				fname = fname[:len(fname)-3]
				splittedFiles = append(splittedFiles, fname + ".[0-9][0-9]")
				files = append(files, fname)
			} else if matched, _ := path.Match("*00", fname); matched {
				fname = fname[:len(fname)-2]
				splittedFiles = append(splittedFiles, fname + "[0-9][0-9]")
				files = append(files, fname)
			} else if matched, _ := path.Match("*_MERGED", fname); matched {
				splittedFiles = append(splittedFiles, fname)
			}
		}

		// Import standard files
		for _, fname := range files {
			if fname == "DIGESTS.txt" {
				continue
			}

			foundSplitted := false
			for _, sf := range splittedFiles {
				if matched, _ := path.Match(sf, fname); matched {
					foundSplitted = true
				}
			}
			if foundSplitted {
				continue
			}

			if f, err := i.importFile(path.Join(exercice.Path, "files", fname),
				func(filePath string, origin string) (interface{}, error) {
					return exercice.ImportFile(filePath, origin, digests[fname])
				}); err != nil {
					errs = append(errs, fmt.Sprintf("%q: unable to import file %q: %s", path.Base(exercice.Path), fname, err))
					continue
				} else if f.(fic.EFile).Size == 0 {
					errs = append(errs, fmt.Sprintf("%q: WARNING imported file %q is empty!", path.Base(exercice.Path), fname))
				}
		}
	}
	return
}