package mpb

import (
	"io"
	"unicode/utf8"

	"github.com/vbauerster/mpb/decor"
)

// BarOption is a function option which changes the default behavior of a bar.
type BarOption func(*bState)

// AppendDecorators let you inject decorators to the bar's right side.
func AppendDecorators(appenders ...decor.Decorator) BarOption {
	return func(s *bState) {
		for _, decorator := range appenders {
			if ar, ok := decorator.(decor.AmountReceiver); ok {
				s.amountReceivers = append(s.amountReceivers, ar)
			}
			if sl, ok := decorator.(decor.ShutdownListener); ok {
				s.shutdownListeners = append(s.shutdownListeners, sl)
			}
			s.aDecorators = append(s.aDecorators, decorator)
		}
	}
}

// PrependDecorators let you inject decorators to the bar's left side.
func PrependDecorators(prependers ...decor.Decorator) BarOption {
	return func(s *bState) {
		for _, decorator := range prependers {
			if ar, ok := decorator.(decor.AmountReceiver); ok {
				s.amountReceivers = append(s.amountReceivers, ar)
			}
			if sl, ok := decorator.(decor.ShutdownListener); ok {
				s.shutdownListeners = append(s.shutdownListeners, sl)
			}
			s.pDecorators = append(s.pDecorators, decorator)
		}
	}
}

// BarID sets bar id.
func BarID(id int) BarOption {
	return func(s *bState) {
		s.id = id
	}
}

// BarRemoveOnComplete is a flag, if set whole bar line will be removed
// on complete event.  If both BarRemoveOnComplete and BarClearOnComplete
// are set, first bar section gets cleared and then whole bar line
// gets removed completely.
func BarRemoveOnComplete() BarOption {
	return func(s *bState) {
		s.removeOnComplete = true
	}
}

// BarReplaceOnComplete is indicator for delayed bar start, after the
// `runningBar` is complete.  To achieve bar replacement effect,
// `runningBar` should has its `BarRemoveOnComplete` option set.
func BarReplaceOnComplete(runningBar *Bar) BarOption {
	return func(s *bState) {
		s.runningBar = runningBar
	}
}

// BarClearOnComplete is a flag, if set will clear bar section on
// complete event.  If you need to remove a whole bar line, refer to
// BarRemoveOnComplete.
func BarClearOnComplete() BarOption {
	return func(s *bState) {
		s.barClearOnComplete = true
	}
}

// BarPriority sets bar's priority.
// Zero is highest priority, i.e. bar will be on top.  If
// `BarReplaceOnComplete` option is supplied, this option is ignored.
func BarPriority(priority int) BarOption {
	return func(s *bState) {
		s.priority = priority
	}
}

// BarNewLineExtend takes user defined efn, which gets called each
// render cycle.  Any write to provided writer of efn, will appear on
// new line of respective bar.
func BarNewLineExtend(efn func(io.Writer, *decor.Statistics)) BarOption {
	return func(s *bState) {
		s.newLineExtendFn = efn
	}
}

// TrimSpace trims bar's edge spaces.
func TrimSpace() BarOption {
	return func(s *bState) {
		s.trimSpace = true
	}
}

// BarStyle sets custom bar style.
// Effective when Filler type is bar.
func BarStyle(style string) BarOption {
	chk := func(filler Filler) (interface{}, bool) {
		if style == "" {
			return nil, false
		}
		t, ok := filler.(*barFiller)
		return t, ok
	}
	cb := func(t interface{}) {
		bf := t.(*barFiller)
		if !utf8.ValidString(style) {
			panic("invalid style string")
		}
		defaultFormat := bf.format
		bf.format = []rune(style)
		if len(bf.format) < 5 {
			bf.format = defaultFormat
		}
	}
	return MakeFillerTypeSpecificBarOption(chk, cb)
}

// SpinnerStyle sets custom spinner style.
// Effective when Filler type is spinner.
func SpinnerStyle(frames []string) BarOption {
	chk := func(filler Filler) (interface{}, bool) {
		if len(frames) == 0 {
			return nil, false
		}
		t, ok := filler.(*spinnerFiller)
		return t, ok
	}
	cb := func(t interface{}) {
		t.(*spinnerFiller).frames = frames
	}
	return MakeFillerTypeSpecificBarOption(chk, cb)
}

// MakeFillerTypeSpecificBarOption makes BarOption specific to Filler's
// actual type.  If you implement your own Filler, so most probably
// you'll need this.  See BarStyle or SpinnerStyle for example.
func MakeFillerTypeSpecificBarOption(
	typeChecker func(Filler) (interface{}, bool),
	cb func(interface{}),
) BarOption {
	return func(s *bState) {
		if t, ok := typeChecker(s.filler); ok {
			cb(t)
		}
	}
}