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imogiri.go
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/
imogiri.go
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package imogiri
import (
"fmt"
"io"
)
type Action int
const (
ResizeAction Action = iota
)
type Engineer interface {
Name() string
MatrixFormats() []string
SupportedActions() []Action
}
type Imogiri struct {
engines map[string]Engineer
formatMatrix map[string][]string
actionMatrix map[Action][]string
resizerEngines map[string][]Resizer
}
func NewImogiri(engines ...Engineer) *Imogiri {
g := &Imogiri{}
for _, e := range engines {
g.RegisterEngine(e)
}
return g
}
func (g *Imogiri) RegisterEngine(engine Engineer) error {
if len(g.engines) == 0 {
g.engines = make(map[string]Engineer)
}
if _, ok := g.engines[engine.Name()]; ok {
return fmt.Errorf("Engine %q already registered", engine.Name())
}
g.engines[engine.Name()] = engine
g.calcFormatMatrix(engine)
g.calcActionMatrix(engine)
return nil
}
func (g *Imogiri) calcFormatMatrix(engine Engineer) {
if len(g.formatMatrix) == 0 {
g.formatMatrix = make(map[string][]string)
}
for _, m := range engine.MatrixFormats() {
if _, ok := g.formatMatrix[m]; !ok {
g.formatMatrix[m] = []string{}
}
g.formatMatrix[m] = append(g.formatMatrix[m], engine.Name())
}
}
func (g *Imogiri) calcActionMatrix(engine Engineer) {
if len(g.actionMatrix) == 0 {
g.actionMatrix = make(map[Action][]string)
}
for _, a := range engine.SupportedActions() {
if _, ok := g.actionMatrix[a]; !ok {
g.actionMatrix[a] = []string{}
}
g.actionMatrix[a] = append(g.actionMatrix[a], engine.Name())
}
}
func (g *Imogiri) enginePicker(matrixFormat string, action Action) (Engineer, error) {
var ae []string
var fe []string
var ok bool
if ae, ok = g.actionMatrix[action]; !ok {
return nil, fmt.Errorf("No registered engine for action: %s", actionString(action))
}
if fe, ok = g.formatMatrix[matrixFormat]; !ok {
return nil, fmt.Errorf("No registered engine for format: %s", matrixFormat)
}
for _, a := range ae {
for _, f := range fe {
if a == f {
return g.engines[f], nil
}
}
}
return nil, fmt.Errorf("No registered engine for handling %s action with format %s", actionString(action), matrixFormat)
}
func (g *Imogiri) Resize(w io.Writer, r io.Reader, opt ResizeOption) error {
e, err := g.enginePicker(opt.matrixFormat(), ResizeAction)
if err != nil {
return err
}
err = e.(Resizer).Resize(w, r, opt)
if err != nil {
return err
}
return nil
}