package cli

import (
	"encoding/json"
	"flag"
	"fmt"
	"strconv"
	"strings"
)

// StringSlice wraps a []string to satisfy flag.Value
type StringSlice struct {
	slice      []string
	hasBeenSet bool
}

// NewStringSlice creates a *StringSlice with default values
func NewStringSlice(defaults ...string) *StringSlice {
	return &StringSlice{slice: append([]string{}, defaults...)}
}

// clone allocate a copy of self object
func (s *StringSlice) clone() *StringSlice {
	n := &StringSlice{
		slice:      make([]string, len(s.slice)),
		hasBeenSet: s.hasBeenSet,
	}
	copy(n.slice, s.slice)
	return n
}

// Set appends the string value to the list of values
func (s *StringSlice) Set(value string) error {
	if !s.hasBeenSet {
		s.slice = []string{}
		s.hasBeenSet = true
	}

	if strings.HasPrefix(value, slPfx) {
		// Deserializing assumes overwrite
		_ = json.Unmarshal([]byte(strings.Replace(value, slPfx, "", 1)), &s.slice)
		s.hasBeenSet = true
		return nil
	}

	for _, t := range flagSplitMultiValues(value) {
		s.slice = append(s.slice, strings.TrimSpace(t))
	}

	return nil
}

// String returns a readable representation of this value (for usage defaults)
func (s *StringSlice) String() string {
	return fmt.Sprintf("%s", s.slice)
}

// Serialize allows StringSlice to fulfill Serializer
func (s *StringSlice) Serialize() string {
	jsonBytes, _ := json.Marshal(s.slice)
	return fmt.Sprintf("%s%s", slPfx, string(jsonBytes))
}

// Value returns the slice of strings set by this flag
func (s *StringSlice) Value() []string {
	return s.slice
}

// Get returns the slice of strings set by this flag
func (s *StringSlice) Get() interface{} {
	return *s
}

// String returns a readable representation of this value
// (for usage defaults)
func (f *StringSliceFlag) String() string {
	return FlagStringer(f)
}

// GetValue returns the flags value as string representation and an empty
// string if the flag takes no value at all.
func (f *StringSliceFlag) GetValue() string {
	var defaultVals []string
	if f.Value != nil && len(f.Value.Value()) > 0 {
		for _, s := range f.Value.Value() {
			if len(s) > 0 {
				defaultVals = append(defaultVals, strconv.Quote(s))
			}
		}
	}
	return strings.Join(defaultVals, ", ")
}

// GetDefaultText returns the default text for this flag
func (f *StringSliceFlag) GetDefaultText() string {
	if f.DefaultText != "" {
		return f.DefaultText
	}
	return f.GetValue()
}

// IsSliceFlag implements DocGenerationSliceFlag.
func (f *StringSliceFlag) IsSliceFlag() bool {
	return true
}

// Apply populates the flag given the flag set and environment
func (f *StringSliceFlag) Apply(set *flag.FlagSet) error {
	// apply any default
	if f.Destination != nil && f.Value != nil {
		f.Destination.slice = make([]string, len(f.Value.slice))
		copy(f.Destination.slice, f.Value.slice)
	}

	// resolve setValue (what we will assign to the set)
	var setValue *StringSlice
	switch {
	case f.Destination != nil:
		setValue = f.Destination
	case f.Value != nil:
		setValue = f.Value.clone()
	default:
		setValue = new(StringSlice)
	}

	if val, source, found := flagFromEnvOrFile(f.EnvVars, f.FilePath); found {
		for _, s := range flagSplitMultiValues(val) {
			if err := setValue.Set(strings.TrimSpace(s)); err != nil {
				return fmt.Errorf("could not parse %q as string value from %s for flag %s: %s", val, source, f.Name, err)
			}
		}

		// Set this to false so that we reset the slice if we then set values from
		// flags that have already been set by the environment.
		setValue.hasBeenSet = false
		f.HasBeenSet = true
	}

	for _, name := range f.Names() {
		set.Var(setValue, name, f.Usage)
	}

	return nil
}

// Get returns the flag’s value in the given Context.
func (f *StringSliceFlag) Get(ctx *Context) []string {
	return ctx.StringSlice(f.Name)
}

// RunAction executes flag action if set
func (f *StringSliceFlag) RunAction(c *Context) error {
	if f.Action != nil {
		return f.Action(c, c.StringSlice(f.Name))
	}

	return nil
}

// StringSlice looks up the value of a local StringSliceFlag, returns
// nil if not found
func (cCtx *Context) StringSlice(name string) []string {
	if fs := cCtx.lookupFlagSet(name); fs != nil {
		return lookupStringSlice(name, fs)
	}
	return nil
}

func lookupStringSlice(name string, set *flag.FlagSet) []string {
	f := set.Lookup(name)
	if f != nil {
		if slice, ok := unwrapFlagValue(f.Value).(*StringSlice); ok {
			return slice.Value()
		}
	}
	return nil
}