package door

import (
	"bytes"
	"fmt"
	"strings"
)

// TODO:  Break out the progress bar characters into structures.
// Write tests to verify that CP437 matches Unicode.
// See box_test.  ;)

type BarStyle int8

const (
	SOLID BarStyle = iota
	HALF_STEP
	GRADIENT
)

type Percent_Style int8

const (
	PERCENT_NONE Percent_Style = iota
	PERCENT
	PERCENT_SPACE
)

type BarRange struct {
	Percent int64
	Color   []byte
}

type BarLine struct {
	Width        int
	Style        BarStyle
	Percent      int64 // percentage * 100
	PercentStyle Percent_Style
	ColorRange   []BarRange
	UpdateP      func() int64
	Line
}

type BarCharacters struct {
	Solid    string
	Half     [2]string
	Gradient [4]string
}

var BARS_CP437 = BarCharacters{
	"\xdb",
	[2]string{"\xdb", "\xdd"},
	[4]string{"\xdb", "\xb0", "\xb1", "\xb2"},
}

var BARS_UNICODE = BarCharacters{
	"\u2588",
	[2]string{"\u2588", "\u258c"},
	[4]string{"\u2588", "\u2591", "\u2592", "\u2593"},
}

var BARS *BarCharacters = &BARS_CP437

func (bl *BarLine) CheckRange() {
	if len(bl.ColorRange) != 0 {
		// Ok, there is a color range.  Get checking

		for _, br := range bl.ColorRange {
			if bl.Percent <= br.Percent {
				bl.DefaultColor = br.Color
				break
			}
		}
	}
}

func (bl *BarLine) Output() []byte {
	// bl.Text & bl.render & bl.update
	if bl.render == nil {
		bl.render = &bytes.Buffer{}
	}
	bl.render.Reset()

	var step_width int64

	if bl.UpdateP != nil {
		bl.Percent = bl.UpdateP()
	}

	bl.CheckRange()
	// CheckRange can change the DefaultColor.
	bl.render.Write(bl.DefaultColor)

	if bl.update == nil {
		bl.update = &bytes.Buffer{}
	}
	bl.update.Reset()

	switch bl.Style {
	case SOLID:
		step_width = int64(100 * 100 / bl.Width)
		var steps int = int(bl.Percent / step_width)

		bl.update.WriteString(strings.Repeat(BARS.Solid, steps))
		// This will work, because we aren't trying to len(output) with unicode.
		bl.update.WriteString(strings.Repeat(" ", int(bl.Width-steps)))

	case HALF_STEP:
		step_width = int64(100 * 100 / bl.Width)
		var steps int = int(bl.Percent * 2 / step_width)

		bl.update.WriteString(strings.Repeat(BARS.Half[0], steps/2))
		if steps%2 == 1 {
			bl.update.WriteString(BARS.Half[1])
			steps++
		}
		bl.update.WriteString(strings.Repeat(" ", bl.Width-(steps/2)))

	case GRADIENT:
		step_width = int64(100 * 100 / bl.Width)
		var steps int = int(bl.Percent * 4 / step_width)

		bl.update.WriteString(strings.Repeat(BARS.Gradient[0], steps/4))
		if steps%4 != 0 {
			switch steps % 4 {
			case 1, 2, 3:
				bl.update.WriteString(BARS.Gradient[steps%4])
			}
			for steps%4 != 0 {
				steps++
			}
		}
		bl.update.WriteString(strings.Repeat(" ", bl.Width-(steps/4)))
	}

	if bl.PercentStyle != PERCENT_NONE {
		var pctbuff [10]byte
		var percent = pctbuff[0:0]
		percent = fmt.Appendf(percent, "%d", bl.Percent/100)

		var pos int = bl.Width/2 - 1
		if bytes.Compare(percent, []byte("100")) != 0 {
			percent = append(percent, '%')
			if len(percent) < 3 {
				percent = append(percent, ' ')
				copy(percent[1:], percent[0:])
				percent[0] = ' '
				// percent = " " + percent
			}
		}

		if bl.PercentStyle == PERCENT_SPACE {
			percent = append(percent, ' ')
			copy(percent[1:], percent[0:])
			percent = append(percent, ' ')
			percent[0] = ' '
			// percent = " " + percent + " "
			pos--
		}

		// to process/slice the string (with unicode) do this:
		// convert to []rune, slice that, convert back to string
		//
		// sliceable := []rune(output)
		// newString := string(sliceable[:5]) + " new content " + (sliceable[10:])
		// fmt.Printf("%d %d [%s] %d [%s]\n", bl.Width, pos, percent, len(output), output)

		// The % part -- isn't working at the moment.
		// I need to insert the percent into the buffer. (but how)?
		// and unicode?  hmm!

		// Note: This takes ownership of update.
		bl.Text = bytes.NewBuffer(bl.update.Bytes())

		var idx int = 0
		if Unicode {
			for {
				rune, _, err := bl.Text.ReadRune()
				if err != nil {
					break
				}
				if (idx >= pos) && (idx < len(percent)+pos) {
					bl.render.WriteByte(percent[idx-pos])
				} else {
					bl.render.WriteRune(rune)
				}
				idx++
			}
			/*
				runes := []rune(output)
				for idx, b := range percent {
					runes[pos+idx] = rune(b)
				}
				output = string(runes[:pos]) + percent + string(runes[pos+len(percent):])
			*/
		} else {

			for {
				b, err := bl.Text.ReadByte()
				if err != nil {
					break
				}
				if (idx >= pos) && (idx < len(percent)+pos) {
					bl.render.WriteByte(percent[idx-pos])
				} else {
					bl.render.WriteByte(b)
				}
				idx++

			}
			/*
				for idx, b := range percent {
					render[pos+idx] = b
				}
			*/
			// output = output[:pos] + percent + output[pos+len(percent):]
		}
		_ = idx

	} else {
		bl.render.Write(bl.update.Bytes())
	}

	// return bl.DefaultColor + output
	return bl.render.Bytes()
}