package allg5

// #include <allegro5/allegro.h>
// #include <stdlib.h>
import "C"

import (
	"errors"
	"image"
	"unsafe"
)

// Bitmap represents an in memory bitmap
type Bitmap struct {
	bitmap *C.ALLEGRO_BITMAP
	width  int
	height int
	subs   []*Bitmap
}

type DrawOptions struct {
	Center   bool
	Scale    *Scale
	Tint     *Color
	Rotation *Rotation
}

type Scale struct {
	Horizontal float32
	Vertical   float32
}

func NewScale(hor, ver float32) *Scale {
	return &Scale{hor, ver}
}

func NewUniformScale(s float32) *Scale {
	return &Scale{s, s}
}

type Rotation struct {
	Angle  float32
	Center bool
}

func newBitmap(width, height int, mut func(m FlagMutation), flags []NewBitmapFlag) (*Bitmap, error) {
	var newBmpFlags = CaptureNewBitmapFlags()
	defer newBmpFlags.Revert()
	newBmpFlags.Mutate(func(m FlagMutation) {
		if mut != nil {
			mut(m)
		}
		for _, f := range flags {
			m.Set(f)
		}
	})
	b := C.al_create_bitmap(C.int(width), C.int(height))
	if b == nil {
		return nil, errors.New("error creating bitmap")
	}
	return &Bitmap{b, width, height, nil}, nil
}

// NewBitmap creates a new bitmap of given width and height and optional flags
func NewBitmap(width, height int, flags ...NewBitmapFlag) (*Bitmap, error) {
	return newBitmap(width, height, nil, flags)
}

// NewVideoBitmap creates a new video bitmap of given width and height and optional flags
func NewVideoBitmap(width, height int, flags ...NewBitmapFlag) (*Bitmap, error) {
	return newBitmap(width, height, func(m FlagMutation) {
		m.Unset(NewBitmapFlagMemoryBitmap)
		m.Set(NewBitmapFlagVideoBitmap)
	}, flags)
}

// NewMemoryBitmap creates a new video bitmap of given width and height and optional flags
func NewMemoryBitmap(width, height int, flags ...NewBitmapFlag) (*Bitmap, error) {
	return newBitmap(width, height, func(m FlagMutation) {
		m.Unset(NewBitmapFlagVideoBitmap)
		m.Set(NewBitmapFlagMemoryBitmap)
	}, flags)
}

// NewBitmapFromImage creates a new bitmap starting from a Go native image (image.Image)
func NewBitmapFromImage(src image.Image, video bool) (*Bitmap, error) {
	var newBmpFlags = CaptureNewBitmapFlags()
	defer newBmpFlags.Revert()
	newBmpFlags.Mutate(func(m FlagMutation) {
		m.Unset(NewBitmapFlagVideoBitmap)
		m.Set(NewBitmapFlagMemoryBitmap)
		m.Set(NewBitmapFlagMinLinear)
	})
	var bnd = src.Bounds()
	width, height := bnd.Dx(), bnd.Dy()
	var b = C.al_create_bitmap(C.int(width), C.int(height))
	if b == nil {
		return nil, errors.New("error creating memory bitmap")
	}
	region := C.al_lock_bitmap(b, C.ALLEGRO_PIXEL_FORMAT_ABGR_8888, C.ALLEGRO_LOCK_WRITEONLY)
	if region == nil {
		C.al_destroy_bitmap(b)
		return nil, errors.New("unable to lock bitmap")
	}
	dst := (*[1 << 30]uint8)(region.data)
	for y := 0; y < height; y++ {
		row := dst[y*int(region.pitch):]
		for x := 0; x < width; x++ {
			r, g, b, a := src.At(x, y).RGBA()
			row[x*4] = uint8(r >> 8)
			row[x*4+1] = uint8(g >> 8)
			row[x*4+2] = uint8(b >> 8)
			row[x*4+3] = uint8(a >> 8)
		}
	}
	C.al_unlock_bitmap(b)
	if video {
		newBmpFlags.Mutate(func(m FlagMutation) {
			m.Unset(NewBitmapFlagMemoryBitmap)
			m.Set(NewBitmapFlagVideoBitmap)
			m.Set(NewBitmapFlagMinLinear)
		})
		C.al_convert_bitmap(b)
	}
	return &Bitmap{b, width, height, nil}, nil
}

// LoadBitmap tries to load the image at the specified path as a bitmap
func LoadBitmap(path string) (*Bitmap, error) {
	p := C.CString(path)
	defer C.free(unsafe.Pointer(p))
	b := C.al_load_bitmap(p)
	if b == nil {
		return nil, errors.New("error loading bitmap")
	}
	width := int(C.al_get_bitmap_width(b))
	height := int(C.al_get_bitmap_height(b))
	return &Bitmap{b, width, height, nil}, nil
}

// Draw draws the bitmap at the given location
func (b *Bitmap) Draw(left, top float32) {
	C.al_draw_bitmap(b.bitmap, C.float(left), C.float(top), 0)
}

func (b *Bitmap) DrawOptions(left, top float32, options DrawOptions) {
	width := float32(b.width)
	height := float32(b.height)

	scale := options.Scale != nil
	if scale {
		width *= options.Scale.Horizontal
		height *= options.Scale.Vertical
	}
	if options.Center {
		left -= width * 0.5
		top -= height * 0.5
	}
	rotated := options.Rotation != nil
	var centerX C.float
	var centerY C.float
	if rotated && options.Rotation.Center {
		centerX = C.float(b.width) * 0.5
		centerY = C.float(b.height) * 0.5
	}

	if scale {
		if options.Tint == nil { // scaled
			if rotated { // scaled & rotated
				C.al_draw_scaled_rotated_bitmap(b.bitmap, centerX, centerY, C.float(left), C.float(top), C.float(options.Scale.Horizontal), C.float(options.Scale.Vertical), C.float(options.Rotation.Angle), 0)
			} else { // scaled
				C.al_draw_scaled_bitmap(b.bitmap, 0, 0, C.float(b.width), C.float(b.height), C.float(left), C.float(top), C.float(width), C.float(height), 0)
			}
		} else { // tinted & scaled
			if rotated { // scaled, tinted & rotated
				C.al_draw_tinted_scaled_rotated_bitmap(b.bitmap, options.Tint.color, centerX, centerY, C.float(left), C.float(top), C.float(options.Scale.Horizontal), C.float(options.Scale.Vertical), C.float(options.Rotation.Angle), 0)
			} else { // tinted, scaled
				C.al_draw_tinted_scaled_bitmap(b.bitmap, options.Tint.color, 0, 0, C.float(b.width), C.float(b.height), C.float(left), C.float(top), C.float(width), C.float(height), 0)
			}
		}
	} else {
		if options.Tint == nil {
			if rotated { // rotated
				C.al_draw_rotated_bitmap(b.bitmap, centerX, centerY, C.float(left), C.float(top), C.float(options.Rotation.Angle), 0)
			} else {
				C.al_draw_bitmap(b.bitmap, C.float(left), C.float(top), 0)
			}
		} else { // tinted
			if rotated { // tinted & rotated
				C.al_draw_tinted_rotated_bitmap(b.bitmap, options.Tint.color, centerX, centerY, C.float(left), C.float(top), C.float(options.Rotation.Angle), 0)
			} else {
				C.al_draw_tinted_bitmap(b.bitmap, options.Tint.color, C.float(left), C.float(top), 0)
			}
		}
	}
}

// Sub creates a sub-bitmap of the original bitmap
func (b *Bitmap) Sub(x, y, w, h int) *Bitmap {
	var sub = C.al_create_sub_bitmap(b.bitmap, C.int(x), C.int(y), C.int(w), C.int(h))
	if sub == nil {
		return nil
	}
	var bmp = &Bitmap{sub, w, h, nil}
	b.subs = append(b.subs, bmp)
	return bmp
}

// Subs returns the slice of sub-bitmaps
func (b *Bitmap) Subs() []*Bitmap {
	return b.subs
}

func (b *Bitmap) Width() int {
	return b.width
}

func (b *Bitmap) Height() int {
	return b.height
}

func (b *Bitmap) Image() image.Image {
	im := image.NewRGBA(image.Rect(0, 0, b.width, b.height))
	region := C.al_lock_bitmap(b.bitmap, C.ALLEGRO_PIXEL_FORMAT_ABGR_8888, C.ALLEGRO_LOCK_READONLY)
	if region == nil {
		return nil
	}
	defer C.al_unlock_bitmap(b.bitmap)
	src := (*[1 << 30]uint8)(region.data)
	dst := im.Pix
	var srcOff, dstOff int
	for y := 0; y < b.height; y++ {
		copy(dst[dstOff:], src[srcOff:srcOff+b.width*4])
		srcOff += int(region.pitch)
		dstOff += im.Stride
	}
	return im
}

func (b *Bitmap) SetAsTarget() {
	C.al_set_target_bitmap(b.bitmap)
}

// Destroy destroys the bitmap
func (b *Bitmap) Destroy() {
	var bmp = b.bitmap
	if bmp == nil {
		return
	}
	b.bitmap = nil
	for _, sub := range b.subs {
		sub.Destroy()
	}
	C.al_destroy_bitmap(bmp)
}