package sync

import (
	"errors"
	"fmt"
	"math/rand"
	"path"
	"sort"
	"strings"
	"unicode"

	"github.com/julienschmidt/httprouter"

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

// isFullGraphic detects if some rune are not graphic one.
// This function is usefull to display warning when importing key ending with \r.
func isFullGraphic(s string) bool {
	for _, c := range s {
		if !unicode.IsGraphic(c) {
			return false
		}
	}
	return true
}

func validatorRegexp(vre string) (validator_regexp *string) {
	if len(vre) > 0 {
		validator_regexp = &vre
	} else {
		validator_regexp = nil
	}
	return
}

func getRawKey(input interface{}, validatorRe string, ordered bool, showLines bool) (raw string, prep string, errs []string) {
	separator := ","

	// Concatenate array
	if f, ok := input.([]interface{}); ok {
		if len(validatorRe) > 0 {
			errs = append(errs, "ValidatorRe cannot be defined for this kind of flag.")
			validatorRe = ""
		}

		if len(separator) == 0 {
			separator = ","
		} else if len(separator) > 1 {
			separator = string(separator[0])
			errs = append(errs, "separator truncated to %q")
		}

		var fitems []string
		for _, v := range f {
			if g, ok := v.(string); ok {
				if strings.Index(g, separator) != -1 {
					errs = append(errs, "flag items cannot contain %q character as it is used as separator. Change the separator attribute for this flag.")
					return
				} else {
					fitems = append(fitems, g)
				}
			} else {
				errs = append(errs, "item %d has an invalid type: can only be string, is %T.")
				return
			}
		}

		ignord := "f"
		if !ordered {
			sort.Strings(fitems)
			ignord = "t"
		}

		nbLines := 0
		if showLines {
			if len(fitems) > 9 {
				errs = append(errs, "too much items in vector to use ShowLines features, max 9.")
			} else {
				nbLines = len(fitems)
			}
		}

		raw = strings.Join(fitems, separator) + separator

		prep = fmt.Sprintf("`%s%s%d", separator, ignord, nbLines)
	} else if f, ok := input.(int64); ok {
		raw = fmt.Sprintf("%d", f)
	} else if f, ok := input.(string); !ok {
		errs = append(errs, fmt.Sprintf("has an invalid type: can only be []string or string, not %T", input))
		return
	} else {
		raw = f
	}
	return
}

func buildKeyFlag(exercice fic.Exercice, flag ExerciceFlag, flagline int, defaultLabel string) (f *fic.Flag, choices []fic.FlagChoice, errs []string) {
	if len(flag.Label) == 0 {
		flag.Label = defaultLabel
	}

	if flag.Label[0] == '`' {
		errs = append(errs, fmt.Sprintf("%q: flag #%d: Label should not begin with `.", path.Base(exercice.Path), flagline))
		flag.Label = flag.Label[1:]
	}

	if flag.Label[len(flag.Label)-1] != ')' && flag.Label[len(flag.Label)-1] != '©' && !unicode.IsLetter(rune(flag.Label[len(flag.Label)-1])) && !unicode.IsDigit(rune(flag.Label[len(flag.Label)-1])) {
		errs = append(errs, fmt.Sprintf("%q: flag #%d: Label should not end with punct (%q). Reword your label as a description of the expected flag, `:` are automatically appended.", path.Base(exercice.Path), flagline, flag.Label[len(flag.Label)-1]))
	}

	raw, prep, terrs := getRawKey(flag.Raw, flag.ValidatorRe, flag.Ordered, flag.ShowLines)

	if len(terrs) > 0 {
		for _, err := range terrs {
			errs = append(errs, fmt.Sprintf("%q: flag #%d: %s", path.Base(exercice.Path), flagline, err))
		}
		f = nil
		return
	}
	flag.Label = prep + flag.Label

	if (flag.Type == "text" && !isFullGraphic(strings.Replace(raw, "\n", "", -1))) || (flag.Type != "text" && !isFullGraphic(raw)) {
		errs = append(errs, fmt.Sprintf("%q: WARNING flag #%d: non-printable characters in flag, is this really expected?", path.Base(exercice.Path), flagline))
	}

	hashedFlag, err := fic.ComputeHashedFlag([]byte(raw), !flag.CaseSensitive, validatorRegexp(flag.ValidatorRe))
	if err != nil {
		errs = append(errs, err.Error())
		return
	}
	fl := fic.Flag(fic.FlagKey{
		IdExercice:      exercice.Id,
		Label:           flag.Label,
		Help:            flag.Help,
		IgnoreCase:      !flag.CaseSensitive,
		Multiline:       flag.Type == "text",
		ValidatorRegexp: validatorRegexp(flag.ValidatorRe),
		Checksum:        hashedFlag[:],
		ChoicesCost:     flag.ChoicesCost,
	})
	f = &fl

	if len(flag.Choice) > 0 || flag.Type == "ucq" {
		// Import choices
		hasOne := false

		if !flag.NoShuffle {
			rand.Shuffle(len(flag.Choice), func(i, j int) {
				flag.Choice[i], flag.Choice[j] = flag.Choice[j], flag.Choice[i]
			})
		}

		for _, choice := range flag.Choice {
			val, prep, terrs := getRawKey(choice.Value, "", false, false)
			if len(terrs) > 0 {
				for _, err := range terrs {
					errs = append(errs, fmt.Sprintf("%q: flag #%d: %s", path.Base(exercice.Path), flagline, err))
				}
				continue
			}

			if len(choice.Label) == 0 {
				choice.Label = val
			}
			choice.Label = prep + choice.Label

			choices = append(choices, fic.FlagChoice{
				Label: choice.Label,
				Value: val,
			})

			if val == raw {
				hasOne = true
			}
		}
		if !hasOne {
			errs = append(errs, fmt.Sprintf("%q: error in flag #%d: no valid answer defined.", path.Base(exercice.Path), flagline))
		}
	}
	return
}

type importFlag struct {
	Line      int
	Flag      fic.Flag
	Choices   []fic.FlagChoice
	FilesDeps []string
	FlagsDeps []int64
}

// buildExerciceFlags read challenge.txt and extract all flags.
func buildExerciceFlag(i Importer, exercice fic.Exercice, flag ExerciceFlag, nline int) (ret []importFlag, errs []string) {
	switch strings.ToLower(flag.Type) {
	case "":
		flag.Type = "key"
	case "key":
		flag.Type = "key"
	case "text":
		flag.Type = "text"
	case "vector":
		flag.Type = "vector"
	case "ucq":
		flag.Type = "ucq"
	case "mcq":
		flag.Type = "mcq"
	default:
		errs = append(errs, fmt.Sprintf("%q: flag #%d: invalid type of flag: should be 'key', 'text', 'mcq', 'ucq' or 'vector'.", path.Base(exercice.Path), nline+1))
		return
	}

	if flag.Type == "key" || flag.Type == "text" || flag.Type == "ucq" || flag.Type == "vector" {
		addedFlag, choices, berrs := buildKeyFlag(exercice, flag, nline+1, "Flag")
		if len(berrs) > 0 {
			errs = append(errs, berrs...)
		}
		if addedFlag != nil {
			ret = append(ret, importFlag{
				Line:    nline + 1,
				Flag:    *addedFlag,
				Choices: choices,
			})
		}
	} else if flag.Type == "mcq" {
		addedFlag := fic.MCQ{
			IdExercice: exercice.Id,
			Title:      flag.Label,
			Entries:    []fic.MCQ_entry{},
		}

		hasOne := false
		isJustified := false

		if !flag.NoShuffle {
			rand.Shuffle(len(flag.Choice), func(i, j int) {
				flag.Choice[i], flag.Choice[j] = flag.Choice[j], flag.Choice[i]
			})
		}

		for cid, choice := range flag.Choice {
			var val bool

			if choice.Raw != nil {
				if hasOne && !isJustified {
					errs = append(errs, fmt.Sprintf("%q: error MCQ #%d: all true items has to be justified in this MCQ.", path.Base(exercice.Path), nline+1))
					continue
				}

				val = true
				isJustified = true
			} else if p, ok := choice.Value.(bool); ok {
				val = p
				if isJustified {
					errs = append(errs, fmt.Sprintf("%q: error MCQ #%d: all true items has to be justified in this MCQ.", path.Base(exercice.Path), nline+1))
					continue
				}
			} else if choice.Value == nil {
				val = false
			} else {
				errs = append(errs, fmt.Sprintf("%q: error in MCQ %d choice %d: incorrect type for value: %T is not boolean.", path.Base(exercice.Path), nline+1, cid, choice.Value))
				continue
			}

			addedFlag.Entries = append(addedFlag.Entries, fic.MCQ_entry{
				Label:    choice.Label,
				Response: val,
			})

			if isJustified && choice.Raw != nil {
				addedFlag, choices, berrs := buildKeyFlag(exercice, choice.ExerciceFlag, nline+1, "Flag correspondant")
				if len(berrs) > 0 {
					errs = append(errs, berrs...)
				}
				if addedFlag != nil {
					ret = append(ret, importFlag{
						Line:    nline + 1,
						Flag:    *addedFlag,
						Choices: choices,
					})
				}
			}
		}

		ret = append(ret, importFlag{
			Line:    nline + 1,
			Flag:    addedFlag,
		})
	}
	return
}

// buildExerciceFlags read challenge.txt and extract all flags.
func buildExerciceFlags(i Importer, exercice fic.Exercice) (flags map[int64]importFlag, flagids []int64, errs []string) {
	params, gerrs := getExerciceParams(i, exercice)
	if len(gerrs) > 0 {
		return flags, flagids, gerrs
	}

	flags = map[int64]importFlag{}

	for nline, flag := range params.Flags {
		if flag.Id == 0 {
			// TODO: should be more smart than that. Perhaps search to increment if possible.
			flag.Id = rand.Int63()
		}

		// Ensure flag ID is unique
		for _, ok := flags[flag.Id]; ok; _, ok = flags[flag.Id] {
			errs = append(errs, fmt.Sprintf("%q: flag #%d: identifier already used (%d), using a random one.", path.Base(exercice.Path), nline+1, flag.Id))
			flag.Id = rand.Int63()
		}

		newFlags, ferrs := buildExerciceFlag(i, exercice, flag, nline)
		if len(ferrs) > 0 {
			errs = append(errs, ferrs...)
		}
		if len(newFlags) > 0 {
			for _, newFlag := range newFlags {
				fId := flag.Id
				for _, ok := flags[fId]; ok; _, ok = flags[fId] {
					fId = rand.Int63()
				}

				// Read dependency to flag
				for _, nf := range flag.NeedFlag {
					newFlag.FlagsDeps = append(newFlag.FlagsDeps, nf.Id)
				}

				// Read dependency to file
				for _, lf := range flag.LockedFile {
					newFlag.FilesDeps = append(newFlag.FilesDeps, lf.Filename)
				}

				flags[fId] = newFlag
				flagids = append(flagids, fId)
			}
		}
	}

	return
}

// CheckExerciceFlags checks if all flags for the given challenge are correct.
func CheckExerciceFlags(i Importer, exercice fic.Exercice, files []string) (rf []fic.Flag, errs []string) {
	flags, flagsids, berrs := buildExerciceFlags(i, exercice)
	errs = append(errs, berrs...)

	for _, flagid := range flagsids {
		if flag, ok := flags[flagid]; ok {
			// Check dependency to flag
			for _, nf := range flag.FlagsDeps {
				if _, ok := flags[nf]; !ok {
					errs = append(errs, fmt.Sprintf("%q: error flag #%d dependency to flag id=%d: id not defined", path.Base(exercice.Path), flag.Line, nf))
				}
			}

			// Check dependency to file
			for _, lf := range flag.FilesDeps {
				found := false
				for _, f := range files {
					if f == lf {
						found = true
						break
					}
				}
				if !found {
					errs = append(errs, fmt.Sprintf("%q: error flag #%d dependency to %s: No such file", path.Base(exercice.Path), flag.Line, lf))
				}
			}

			rf = append(rf, flag.Flag)
		}
	}

	return
}

// ExerciceFlagsMap builds the flags bindings between challenge.txt and DB.
func ExerciceFlagsMap(i Importer, exercice fic.Exercice) (kmap map[int64]fic.Flag) {
	flags, flagids, _ := buildExerciceFlags(i, exercice)

	kmap = map[int64]fic.Flag{}

	for _, flagid := range flagids {
		if flag, ok := flags[flagid]; ok {
			if addedFlag, err := flag.Flag.RecoverId(); err == nil {
				kmap[flagid] = addedFlag
			}
		}
	}

	return
}


// SyncExerciceFlags imports all kind of flags for the given challenge.
func SyncExerciceFlags(i Importer, exercice fic.Exercice) (kmap map[int64]fic.Flag, errs []string) {
	if _, err := exercice.WipeFlags(); err != nil {
		errs = append(errs, err.Error())
	} else if _, err := exercice.WipeMCQs(); err != nil {
		errs = append(errs, err.Error())
	} else {
		flags, flagids, berrs := buildExerciceFlags(i, exercice)
		errs = append(errs, berrs...)

		kmap = map[int64]fic.Flag{}

		// Import flags
		for _, flagid := range flagids {
			if flag, ok := flags[flagid]; ok {
				if addedFlag, err := exercice.AddFlag(flag.Flag); err != nil {
					errs = append(errs, fmt.Sprintf("%q: error flag #%d: %s", path.Base(exercice.Path), flag.Line, err))
				} else {
					if f, ok := addedFlag.(fic.FlagKey); ok {
						for _, choice := range flag.Choices {
							if _, err := f.AddChoice(choice); err != nil {
								errs = append(errs, fmt.Sprintf("%q: error in flag #%d choice #FIXME: %s", path.Base(exercice.Path), flag.Line, err))
							}
						}
					}

					kmap[flagid] = addedFlag

					// Import dependency to flag
					for _, nf := range flag.FlagsDeps {
						if rf, ok := kmap[nf]; !ok {
							errs = append(errs, fmt.Sprintf("%q: error flag #%d dependency to flag id=%d: id not defined, perhaps not available at time of processing", path.Base(exercice.Path), flag.Line, nf))
						} else if err := addedFlag.AddDepend(rf); err != nil {
							errs = append(errs, fmt.Sprintf("%q: error flag #%d dependency to id=%d: %s", path.Base(exercice.Path), flag.Line, nf, err))
						}
					}

					// Import dependency to file
					for _, lf := range flag.FilesDeps {
						if rf, err := exercice.GetFileByFilename(lf); err != nil {
							errs = append(errs, fmt.Sprintf("%q: error flag #%d dependency to %s: %s", path.Base(exercice.Path), flag.Line, lf, err))
						} else if err := rf.AddDepend(addedFlag); err != nil {
							errs = append(errs, fmt.Sprintf("%q: error flag #%d dependency to %s: %s", path.Base(exercice.Path), flag.Line, lf, err))
						}
					}
				}
			}
		}
	}

	return
}

// ApiListRemoteExerciceFlags is an accessor letting foreign packages to access remote exercice flags.
func ApiGetRemoteExerciceFlags(ps httprouter.Params, _ []byte) (interface{}, error) {
	theme, errs := BuildTheme(GlobalImporter, ps.ByName("thid"))
	if theme != nil {
		exercice, _, _, _, errs := BuildExercice(GlobalImporter, *theme, path.Join(theme.Path, ps.ByName("exid")), nil)
		if exercice != nil {
			flags, errs := CheckExerciceFlags(GlobalImporter, *exercice, []string{})
			if flags != nil {
				return flags, nil
			} else {
				return flags, errors.New(fmt.Sprintf("%q", errs))
			}
		} else {
			return exercice, errors.New(fmt.Sprintf("%q", errs))
		}
	} else {
		return nil, errors.New(fmt.Sprintf("%q", errs))
	}
}