package tss

import "os"
import "git.tebibyte.media/tomo/tomo/event"
import "git.tebibyte.media/tomo/backend/style"

type Sheet struct {
	Path      string
	Variables map[string] ValueList
	Rules     []Rule
	flat      bool
}

type Rule struct {
	Selector Selector
	Attrs    map[string] []ValueList
}

type Selector struct {
	Package string
	Object  string
	Tags    []string
}

type ValueList []Value

type Value interface {
	value ()
}

type ValueNumber int
func (ValueNumber) value () { }

type ValueColor uint32
func (ValueColor) value () { }
func (value ValueColor) RGBA () (r, g, b, a uint32) {
	// extract components
	bits := uint32(value)
	r = (bits & 0xFF000000) >> 24
	g = (bits & 0x00FF0000) >> 16
	b = (bits & 0x0000FF00) >> 8
	a = (bits & 0x000000FF)
	// extend to 16 bits per channel
	r = r << 8 | r
	g = g << 8 | g
	b = b << 8 | b
	a = a << 8 | a
	// alpha premultiply
	r = (r * a) / 0xFFFF
	g = (g * a) / 0xFFFF
	b = (b * a) / 0xFFFF
	return
}

type ValueString string
func (ValueString) value () { }

type ValueKeyword string
func (ValueKeyword) value () { }

type ValueVariable string
func (ValueVariable) value () { }

type ValueCut struct { }
func (ValueCut) value () { }

// LoadFile loads the stylesheet from the specified file. This may return a
// parse.Error, so use parse.Format to print it.
func LoadFile (name string) (*style.Style, event.Cookie, error) {
	// TODO check cache for gobbed sheet. if the cache is nonexistent or
	// invalid, then open/load/cache.
	
	file, err := os.Open(name)
	if err != nil { return nil, nil, err }
	defer file.Close()

	sheet, err := Parse(Lex(name, file))
	if err != nil { return nil, nil, err }
	sheet.Path = name
	return BuildStyle(sheet)
}