package render

import (
	"fmt"

	"git.kirsle.net/apps/doodle/events"
)

// Engine is the interface for the rendering engine, keeping SDL-specific stuff
// far away from the core of Doodle.
type Engine interface {
	Setup() error

	// Poll for events like keypresses and mouse clicks.
	Poll() (*events.State, error)
	GetTicks() uint32

	// Present presents the current state to the screen.
	Present() error

	// Clear the full canvas and set this color.
	Clear(Color)
	DrawPoint(Color, Point)
	DrawLine(Color, Point, Point)
	DrawRect(Color, Rect)
	DrawBox(Color, Rect)
	DrawText(Text, Point) error

	// Delay for a moment using the render engine's delay method,
	// implemented by sdl.Delay(uint32)
	Delay(uint32)

	// Tasks that the Setup function should defer until tear-down.
	Teardown()

	Loop() error // maybe?
}

// Color holds an RGBA color value.
type Color struct {
	Red   uint8
	Green uint8
	Blue  uint8
	Alpha uint8
}

func (c Color) String() string {
	return fmt.Sprintf(
		"Color<#%02x%02x%02x>",
		c.Red, c.Green, c.Blue,
	)
}

// Point holds an X,Y coordinate value.
type Point struct {
	X int32
	Y int32
}

func (p Point) String() string {
	return fmt.Sprintf("Point<%d,%d>", p.X, p.Y)
}

// Rect has a coordinate and a width and height.
type Rect struct {
	X int32
	Y int32
	W int32
	H int32
}

func (r Rect) String() string {
	return fmt.Sprintf("Rect<%d,%d,%d,%d>",
		r.X, r.Y, r.W, r.H,
	)
}

// Text holds information for drawing text.
type Text struct {
	Text   string
	Size   int
	Color  Color
	Stroke Color // Stroke color (if not zero)
	Shadow Color // Drop shadow color (if not zero)
}

func (t Text) String() string {
	return fmt.Sprintf("Text<%s>", t.Text)
}

// Common color names.
var (
	Invisible = Color{}
	White     = Color{255, 255, 255, 255}
	Grey      = Color{153, 153, 153, 255}
	Black     = Color{0, 0, 0, 255}
	SkyBlue   = Color{0, 153, 255, 255}
	Blue      = Color{0, 0, 255, 255}
	Red       = Color{255, 0, 0, 255}
	Green     = Color{0, 255, 0, 255}
	Cyan      = Color{0, 255, 255, 255}
	Yellow    = Color{255, 255, 0, 255}
	Magenta   = Color{255, 0, 255, 255}
	Pink      = Color{255, 153, 255, 255}
)