package main

import (
	"bytes"
	"slices"
	"sync"

	"github.com/gosuri/uiprogress"
	"src.lwithers.me.uk/go/htpack/cmd/htpacker/packer"
)

type uiProgress struct {
	p                          *uiprogress.Progress
	uncompressed, gzip, brotli *uiProgressBar
}

func newUiProgress(ftp packer.FilesToPack) *uiProgress {
	up := &uiProgress{
		p: uiprogress.New(),
	}

	up.uncompressed = newUiProgressBar(up.p, len(ftp), "uncompressed")
	var nGzip, nBrotli int
	for _, f := range ftp {
		if !f.DisableCompression && !f.DisableGzip {
			nGzip++
		}
		if !f.DisableCompression && !f.DisableBrotli {
			nBrotli++
		}
	}
	if nGzip > 0 {
		up.gzip = newUiProgressBar(up.p, nGzip, "gzip")
	}
	if nBrotli > 0 {
		up.brotli = newUiProgressBar(up.p, nGzip, "brotli")
	}

	up.p.Start()
	return up
}

func (up *uiProgress) Count(_ int) {
}

func (up *uiProgress) Begin(filename, compression string) {
	up.bar(compression).begin(filename)
}

func (up *uiProgress) End(filename, compression string) {
	up.bar(compression).end(filename)
}

func (up *uiProgress) bar(compression string) *uiProgressBar {
	switch compression {
	case "uncompressed":
		return up.uncompressed
	case "gzip":
		return up.gzip
	case "brotli":
		return up.brotli
	}
	return nil
}

func (up *uiProgress) Complete() {
	up.p.Stop()
}

type uiProgressBar struct {
	bar      *uiprogress.Bar
	lock     sync.Mutex
	inflight []string
}

func newUiProgressBar(p *uiprogress.Progress, total int, compression string) *uiProgressBar {
	bar := &uiProgressBar{
		bar: p.AddBar(total).AppendCompleted(),
	}

	var buf bytes.Buffer
	bar.bar.PrependFunc(func(*uiprogress.Bar) string {
		bar.lock.Lock()
		defer bar.lock.Unlock()
		buf.Reset()
		buf.WriteString(compression)
		if len(bar.inflight) > 0 {
			buf.WriteString(" (")
			for i, f := range bar.inflight {
				if i > 0 {
					buf.WriteString(", ")
				}
				buf.WriteString(f)
			}
			buf.WriteRune(')')
		}
		if buf.Len() < 40 {
			buf.WriteString("                                        ")
			buf.Truncate(40)
		} else if buf.Len() > 40 {
			buf.Truncate(39)
			buf.WriteString("…")
		}
		return buf.String()
	})

	return bar
}

func (bar *uiProgressBar) begin(filename string) {
	if bar == nil {
		return
	}
	bar.lock.Lock()
	defer bar.lock.Unlock()

	bar.inflight = append(bar.inflight, filename)
}

func (bar *uiProgressBar) end(filename string) {
	if bar == nil {
		return
	}
	bar.lock.Lock()
	defer bar.lock.Unlock()

	bar.bar.Incr()
	if idx := slices.Index(bar.inflight, filename); idx != -1 {
		bar.inflight = slices.Delete(bar.inflight, idx, idx+1)
	}
}