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
	}
}

// BarStyle sets custom bar style.
func BarStyle(style string) BarOption {
	return func(s *bState) {
		if style == "" {
			return
		}
		if bf, ok := s.filler.(*barFiller); ok {
			if !utf8.ValidString(style) {
				panic("invalid style string")
			}
			defaultFormat := bf.format
			bf.format = []rune(style)
			if len(bf.format) < 5 {
				bf.format = defaultFormat
			}
		}
	}
}

// SpinnerStyle sets custom Spinner style.
func SpinnerStyle(frames []string) BarOption {
	return func(s *bState) {
		if len(frames) == 0 {
			return
		}
		if bf, ok := s.filler.(*spinnerFiller); ok {
			bf.frames = frames
		}
	}
}

func TrimSpace() BarOption {
	return func(s *bState) {
		s.trimSpace = true
	}
}