package widgets

import (
	"bytes"
	"fmt"
	"io"
	"os/exec"

	"github.com/emersion/go-imap"
	"github.com/gdamore/tcell"
	"github.com/mattn/go-runewidth"

	"git.sr.ht/~sircmpwn/aerc2/lib"
	"git.sr.ht/~sircmpwn/aerc2/lib/ui"
	"git.sr.ht/~sircmpwn/aerc2/worker/types"
)

type MessageViewer struct {
	cmd    *exec.Cmd
	source io.Reader
	sink   io.WriteCloser
	grid   *ui.Grid
	term   *Terminal
}

func formatAddresses(addrs []*imap.Address) string {
	val := bytes.Buffer{}
	for i, addr := range addrs {
		if addr.PersonalName != "" {
			val.WriteString(fmt.Sprintf("%s <%s@%s>",
				addr.PersonalName, addr.MailboxName, addr.HostName))
		} else {
			val.WriteString(fmt.Sprintf("%s@%s",
				addr.MailboxName, addr.HostName))
		}
		if i != len(addrs)-1 {
			val.WriteString(", ")
		}
	}
	return val.String()
}

func NewMessageViewer(store *lib.MessageStore,
	msg *types.MessageInfo) *MessageViewer {

	grid := ui.NewGrid().Rows([]ui.GridSpec{
		{ui.SIZE_EXACT, 3}, // TODO: Based on number of header rows
		{ui.SIZE_WEIGHT, 1},
	}).Columns([]ui.GridSpec{
		{ui.SIZE_WEIGHT, 1},
	})

	// TODO: let user specify additional headers to show by default
	headers := ui.NewGrid().Rows([]ui.GridSpec{
		{ui.SIZE_EXACT, 1},
		{ui.SIZE_EXACT, 1},
		{ui.SIZE_EXACT, 1},
	}).Columns([]ui.GridSpec{
		{ui.SIZE_WEIGHT, 1},
		{ui.SIZE_WEIGHT, 1},
	})
	headers.AddChild(
		&HeaderView{
			Name:  "From",
			Value: formatAddresses(msg.Envelope.From),
		}).At(0, 0)
	headers.AddChild(
		&HeaderView{
			Name:  "To",
			Value: formatAddresses(msg.Envelope.To),
		}).At(0, 1)
	headers.AddChild(
		&HeaderView{
			Name:  "Subject",
			Value: msg.Envelope.Subject,
		}).At(1, 0).Span(1, 2)
	headers.AddChild(ui.NewFill(' ')).At(2, 0).Span(1, 2)

	body := ui.NewGrid().Rows([]ui.GridSpec{
		{ui.SIZE_WEIGHT, 1},
	}).Columns([]ui.GridSpec{
		{ui.SIZE_WEIGHT, 1},
		{ui.SIZE_EXACT, 20},
	})

	cmd := exec.Command("less")
	pipe, _ := cmd.StdinPipe()
	term, _ := NewTerminal(cmd)
	// TODO: configure multipart view. I left a spot for it in the grid
	body.AddChild(term).At(0, 0).Span(1, 2)

	grid.AddChild(headers).At(0, 0)
	grid.AddChild(body).At(1, 0)

	viewer := &MessageViewer{
		cmd:  cmd,
		sink: pipe,
		grid: grid,
		term: term,
	}

	store.FetchBodyPart(msg.Uid, 0, func(reader io.Reader) {
		viewer.source = reader
		viewer.attemptCopy()
	})

	term.OnStart = func() {
		viewer.attemptCopy()
	}

	return viewer
}

func (mv *MessageViewer) attemptCopy() {
	if mv.source != nil && mv.cmd.Process != nil {
		go func() {
			io.Copy(mv.sink, mv.source)
			mv.sink.Close()
		}()
	}
}

func (mv *MessageViewer) Draw(ctx *ui.Context) {
	mv.grid.Draw(ctx)
}

func (mv *MessageViewer) Invalidate() {
	mv.grid.Invalidate()
}

func (mv *MessageViewer) OnInvalidate(fn func(d ui.Drawable)) {
	mv.grid.OnInvalidate(func(_ ui.Drawable) {
		fn(mv)
	})
}

func (mv *MessageViewer) Event(event tcell.Event) bool {
	return mv.term.Event(event)
}

func (mv *MessageViewer) Focus(focus bool) {
	mv.term.Focus(focus)
}

type HeaderView struct {
	onInvalidate func(d ui.Drawable)

	Name  string
	Value string
}

func (hv *HeaderView) Draw(ctx *ui.Context) {
	name := hv.Name
	size := runewidth.StringWidth(name)
	lim := ctx.Width() - size - 1
	value := runewidth.Truncate(" "+hv.Value, lim, "…")
	var (
		hstyle tcell.Style
		vstyle tcell.Style
	)
	// TODO: Make this more robust and less dumb
	if hv.Name == "PGP" {
		vstyle = tcell.StyleDefault.Foreground(tcell.ColorGreen)
		hstyle = tcell.StyleDefault.Bold(true)
	} else {
		vstyle = tcell.StyleDefault
		hstyle = tcell.StyleDefault.Bold(true)
	}
	ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ', vstyle)
	ctx.Printf(0, 0, hstyle, name)
	ctx.Printf(size, 0, vstyle, value)
}

func (hv *HeaderView) Invalidate() {
	if hv.onInvalidate != nil {
		hv.onInvalidate(hv)
	}
}

func (hv *HeaderView) OnInvalidate(fn func(d ui.Drawable)) {
	hv.onInvalidate = fn
}

type MultipartView struct {
	onInvalidate func(d ui.Drawable)
}

func (mpv *MultipartView) Draw(ctx *ui.Context) {
	ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ', tcell.StyleDefault)
	ctx.Fill(0, 0, ctx.Width(), 1, ' ', tcell.StyleDefault.Reverse(true))
	ctx.Printf(0, 0, tcell.StyleDefault.Reverse(true), "text/plain")
	ctx.Printf(0, 1, tcell.StyleDefault, "text/html")
	ctx.Printf(0, 2, tcell.StyleDefault, "application/pgp-si…")
}

func (mpv *MultipartView) Invalidate() {
	if mpv.onInvalidate != nil {
		mpv.onInvalidate(mpv)
	}
}

func (mpv *MultipartView) OnInvalidate(fn func(d ui.Drawable)) {
	mpv.onInvalidate = fn
}