package buf2d

import (
	"strings"
)

// Buffer is a 2-dimensional rune buffer
type Buffer struct {
	data   [][]rune
	width  int
	height int
	parent *Buffer
}

// NewBuffer makes a new buffer with the given dimensions
func NewBuffer(width, height int) *Buffer {
	b := make([][]rune, height)
	for y := range b {
		b[y] = make([]rune, width)
		for x := range b[y] {
			b[y][x] = ' '
		}
	}

	return &Buffer{
		data:   b,
		width:  width,
		height: height,
		parent: nil,
	}
}

// Set sets the rune at position (x,y) to c
func (b *Buffer) Set(x, y int, c rune) {
	b.data[y][x] = c
}

// Get returns the rune at position (x,y)
func (b *Buffer) Get(x, y int) rune {
	return b.data[y][x]
}

// Size returns width and height of b
func (b *Buffer) Size() (w, h int) {
	return b.width, b.height
}

// Width returns the width of b
func (b *Buffer) Width() int {
	return b.width
}

// Height returns the height of b
func (b *Buffer) Height() int {
	return b.height
}

// Draw calls drawFunc for every rune in this buffer
func (b *Buffer) Draw(drawFunc func(x, y int, c rune)) {
	for y, col := range b.data {
		for x, char := range col {
			drawFunc(x, y, char)
		}
	}
}

func (b *Buffer) String() string {
	s := new(strings.Builder)
	for ci, col := range b.data {
		for _, char := range col {
			s.WriteRune(char)
		}
		if ci != len(b.data)-1 {
			s.WriteRune('\n')
		}
	}
	return s.String()
}

// Sub returns a buffer which is completely contained in this buffer
// Modifying the main buffer or the sub buffer will modify the other one as well
// This method can be used recursively
// If the given dimensions don't fit in the parent buffer, it will be truncated
func (b *Buffer) Sub(x, y, w, h int) *Buffer {
	// sanitize inputs
	x = limit(x, 0, b.width-1)
	y = limit(y, 0, b.height-1)
	w = limit(w, 1, b.width-x)
	h = limit(h, 1, b.height-y)

	// make slice references
	data := make([][]rune, h)
	for dy := 0; dy < h; dy++ {
		col := b.data[y+dy]
		data[dy] = col[x : x+w]
	}

	// make buffer
	return &Buffer{
		data:   data,
		width:  w,
		height: h,
		parent: b,
	}
}