package sizer

import (
	"bufio"
	"fmt"
	"io"
	"os"
)

type dummy struct{}

func (d dummy) Write(p []byte) (n int, err error) {
	return 0, nil
}

// Trivella provides an io.Writer with a notion of depth in the
// path graph
type Trivella struct {
	Level  uint
	Writer io.Writer
}

// Scendi increases the depth in the graph
func (t *Trivella) Scendi() *Trivella {
	var v *Trivella
	if t.Level > 0 {
		v = TrInit(t.Writer, t.Level-1)
	} else {
		var d dummy
		v = TrInit(d, 0)
	}
	return v
}

// TrInit assigns the writer to a Trivella
func TrInit(writer io.Writer, level uint) *Trivella {
	return &Trivella{Writer: writer, Level: level}
}

// Ruspa is the asynchronous worker that is in charge of collecting
// the underlying sizes and relay the total to the eventual parent.
type Ruspa struct {
	INode     *INode
	ReportIn  chan StatusReport
	ReportOut chan StatusReport
	DoneIn    chan StatusReport
	DoneOut   chan StatusReport
	Opened    map[string]*Ruspa
}

// NewRuspa inits a new Ruspa
func NewRuspa(inode *INode, reportOut, doneOut chan StatusReport) *Ruspa {
	var r Ruspa
	r.INode = inode
	r.ReportOut = reportOut
	r.DoneOut = doneOut
	r.ReportIn = make(chan StatusReport)
	r.DoneIn = make(chan StatusReport)
	r.Opened = make(map[string]*Ruspa)
	return &r
}

// Ammucchia gathers the size of the underlying INode(s) from the Ruspa worker
// and adds to the INode size.
func (w *Ruspa) Ammucchia(t *Trivella) {
	Console.Debugln(Gray("Ammucchia:", w.INode.Path))
	for len(w.Opened) > 0 {
		select {
		case report := <-w.ReportIn:
			Console.Debugln(Gray("ReportIn:", report))
			if report.err == nil {
				w.INode.Size += report.size
				fmt.Fprintf(t.Writer, "%s: %d\n", w.INode.Path, w.INode.Size)
			} else {
				Console.Debugln(Red(report.err))
			}
		case leaf := <-w.DoneIn:
			Console.Debugln(Gray("Done:", leaf.path))
			delete(w.Opened, leaf.path)
		}
	}
	Console.Debugln(Gray(w.INode.Path, ": Completed. Exiting..."))
	w.DoneOut <- StatusReport{path: w.INode.Path, size: w.INode.Size}
}

// Scava starts a worker on the given INode.
func (w *Ruspa) Scava(t *Trivella) {
	Console.Debugln(Gray("Scava: ", w.INode.Path))
	children, err := ls(w.INode.Path)
	if err != nil {
		w.ReportOut <- StatusReport{path: w.INode.Path, err: err}
	}
	for _, childPath := range children {
		kind, size, err := IdentifyType(childPath)
		if err != nil {
			w.ReportOut <- StatusReport{path: childPath, err: err}
		}
		childINode := NewINode(kind, size, childPath)
		w.INode.Children.Append(childINode)
		switch {
		case kind == FileType:
			Console.Debugln(Gray("[file]", w.INode.Path, " ~> ", childINode.Path))
			w.ReportOut <- StatusReport{path: childPath, size: size}
		case kind == DirType:
			Console.Debugln(Gray("[dir]", w.INode.Path, " ~> ", childINode.Path))
			w.INode.Size += size
			cw := NewRuspa(childINode, w.ReportIn, w.DoneIn)
			w.Opened[childPath] = cw
			go cw.Scava(t.Scendi())
		}
	}
	if len(w.Opened) != 0 {
		Console.Debugln(Gray("Spawning Ammucchia:", w.INode.Path))
		go w.Ammucchia(t)
	} else {
		w.DoneOut <- StatusReport{path: w.INode.Path, size: w.INode.Size}
	}
}

// Pesa starts the worker for current inode and returns the channel
// to listen to get the size.
func (i *INode) Pesa(t *Trivella, report, done chan StatusReport) {
	w := NewRuspa(i, report, done)
	go w.Scava(t)
}

// NastroConvogliatore starts a Pesa on a given path and displays
// the current value of the size.
func NastroConvogliatore(path string, depth uint) {
	finished := false
	pathINode, err := INodeFromPath(path)
	if err != nil {
		Console.Fatalln("Failed creating inode:", err)
	}
	Console.Debugln(Gray("Starting Pesa on path:", path))
	report := make(chan StatusReport)
	done := make(chan StatusReport)
	writer := bufio.NewWriter(os.Stdout)
	defer writer.Flush()
	t := TrInit(writer, depth)
	fmt.Fprintf(writer, "%s\n", Green("Starting..."))
	pathINode.Pesa(t, report, done)
	for !finished {
		select {
		case res := <-report:
			Console.Debugln(Gray("MAIN: result =>", res))
		case res := <-done:
			Console.Debugln(Gray("MAIN: done =>", res))
			finished = true
		}
	}
	fmt.Fprintf(writer, "%s: %d\n", path, pathINode.Size)
	return
}