package main

import (
	"fmt"
	"time"
	"os"
	"os/exec"
	"regexp"
	"strings"

	"9front/gui/draw"
)

// A button-3 menu, the way page and vdir do it: press 3, drag, release on an
// item. acme's plumb-on-3 is the outlier on this system, so plumbing lives
// in here as an item rather than owning the button.
type menuItem struct {
	label string
	do    func(*state)
}

func (s *state) menu(at draw.Point, mc *draw.Mousectl) {
	items := s.menuItems()
	if len(items) == 0 {
		return
	}

	lh := int32(s.f.Height) + 4
	var w int32
	for _, it := range items {
		if x := s.f.Width(it.label) + 20; x > w {
			w = x
		}
	}
	h := lh*int32(len(items)) + 4
	win := s.win.Rect()
	r := draw.Rect(at.X, at.Y, at.X+w, at.Y+h)
	// Keep it on screen.
	if r.Max.X > win.Max.X {
		r = r.Add(draw.Point{X: win.Max.X - r.Max.X})
	}
	if r.Max.Y > win.Max.Y {
		r = r.Add(draw.Point{Y: win.Max.Y - r.Max.Y})
	}

	sel := -1
	paint := func() {
		s.fill(r, "tag")
		s.fill(draw.Rect(r.Min.X, r.Min.Y, r.Max.X, r.Min.Y+1), "border")
		s.fill(draw.Rect(r.Min.X, r.Max.Y-1, r.Max.X, r.Max.Y), "border")
		s.fill(draw.Rect(r.Min.X, r.Min.Y, r.Min.X+1, r.Max.Y), "border")
		s.fill(draw.Rect(r.Max.X-1, r.Min.Y, r.Max.X, r.Max.Y), "border")
		for i, it := range items {
			ir := draw.Rect(r.Min.X+1, r.Min.Y+2+int32(i)*lh, r.Max.X-1, r.Min.Y+2+int32(i+1)*lh)
			if i == sel {
				s.fill(ir, "today")
			}
			s.text(draw.Point{X: ir.Min.X + 8, Y: ir.Min.Y + 2}, "ink", it.label)
		}
		s.d.Flush()
	}
	itemAt := func(p draw.Point) int {
		if p.X < r.Min.X || p.X >= r.Max.X {
			return -1
		}
		i := int((p.Y - r.Min.Y - 2) / lh)
		if i < 0 || i >= len(items) || p.Y < r.Min.Y+2 {
			return -1
		}
		return i
	}
	paint()

	// Track until button 3 comes back up.
	for m := range mc.C {
		if n := itemAt(m.Point); n != sel {
			sel = n
			paint()
		}
		if m.Buttons&4 == 0 {
			if sel >= 0 {
				items[sel].do(s)
			} else {
				s.redraw()
			}
			return
		}
	}
}

func (s *state) menuItems() []menuItem {
	items := []menuItem{}
	if s.sel != nil {
		items = append(items, menuItem{"Plumb", func(st *state) {
			if err := st.plumb(st.sel); err != nil {
				fmt.Fprintf(os.Stderr, "cal: plumb: %v\n", err)
			}
			st.redraw()
		}})
		items = append(items, menuItem{"Open event", func(st *state) {
			st.openEvent(st.sel)
		}})
		items = append(items, menuItem{"Close event", func(st *state) {
			st.sel = nil
			st.redraw()
		}})
	}
	if s.sel == nil && !s.pick.IsZero() {
		items = append(items, menuItem{"Close day", func(st *state) {
			st.pick = time.Time{}
			st.redraw()
		}})
	}
	// one toggle per calendar, so a crowded work calendar can be put
	// aside without unmounting anything
	for _, c := range s.cals {
		c := c
		mark := "[ ] "
		if s.on[c] {
			mark = "[x] "
		}
		items = append(items, menuItem{mark + c, func(st *state) {
			st.on[c] = !st.on[c]
			st.load()
			st.redraw()
		}})
	}
	// A second view of the calendar is a second cal, in its own window.
	items = append(items, menuItem{"Open " + strings.ToLower(viewName[s.view]),
		func(st *state) { st.openCal(st.view, st.at) }})
	if !s.pick.IsZero() && s.view != vDay {
		d := s.pick
		items = append(items, menuItem{"Open " + d.Format("2 Jan"),
			func(st *state) { st.openCal(vDay, d) }})
	}
	items = append(items,
		menuItem{"Today", func(st *state) {
			st.at = now()
			st.top = 8 * 60
			st.load()
			st.redraw()
		}},
		// rio has no iconify, so "compact" is a resize request: shrink the
		// window and the small-window view takes over by itself.
		menuItem{"Compact", func(st *state) {
			r := st.win.Rect()
			st.wctl(fmt.Sprintf("resize -r %d %d %d %d",
				r.Min.X, r.Min.Y, r.Min.X+320, r.Min.Y+72))
		}},
		menuItem{"Restore", func(st *state) {
			r := st.win.Rect()
			st.wctl(fmt.Sprintf("resize -r %d %d %d %d",
				r.Min.X, r.Min.Y, r.Min.X+820, r.Min.Y+620))
		}},
		menuItem{"Move", func(st *state) { st.track(st.mc, false) }},
		menuItem{"Resize", func(st *state) { st.track(st.mc, true) }},
		menuItem{"Hide", func(st *state) { st.wctl("hide") }},
		menuItem{"Exit", func(st *state) { st.quit = true }},
	)
	return items
}

// wctl asks rio to do something to our window. Errors are worth showing:
// outside rio there is no wctl and the menu items simply do nothing.
func (s *state) wctl(cmd string) {
	f, err := os.OpenFile("/dev/wctl", os.O_WRONLY, 0)
	if err != nil {
		fmt.Fprintf(os.Stderr, "cal: wctl: %v\n", err)
		return
	}
	defer f.Close()
	if _, err := f.WriteString(cmd); err != nil {
		fmt.Fprintf(os.Stderr, "cal: wctl %q: %v\n", cmd, err)
	}
}

var urlRe = regexp.MustCompile(`https?://[^\s<>"]+`)

// plumb sends the event's join link to the plumber, falling back to the
// event file itself, which lands in acme.
func (s *state) plumb(e *event) error {
	data := e.file
	if body, err := os.ReadFile(e.file); err == nil {
		if m := urlRe.Find(body); m != nil {
			data = strings.TrimRight(string(m), ".,)")
		}
	}
	return exec.Command("/bin/plumb", data).Run()
}

// track implements Move and Resize ourselves. rio's wctl has no "let the
// user sweep" verb -- only move/resize with an explicit rectangle -- so we
// follow the pointer and write a new rect as it goes, and rio does the
// actual work. Any button press drops the window where it is.
//
// rio hands out a new image whenever the window's screen rect changes, so
// this loop has to service resize events as well as motion, or every write
// would be drawing into a stale image.
func (s *state) track(mc *draw.Mousectl, resize bool) {
	r := s.win.Rect()
	w, h := r.Dx(), r.Dy()
	grab := draw.Point{} // pointer offset within the window, for Move
	first := true
	last := r

	for {
		select {
		case m, ok := <-mc.C:
			if !ok {
				return
			}
			if first {
				grab = draw.Point{X: m.X - r.Min.X, Y: m.Y - r.Min.Y}
				first = false
				continue
			}
			if m.Buttons != 0 { // any press drops it
				s.redraw()
				return
			}
			var nr draw.Rectangle
			if resize {
				nr = draw.Rect(r.Min.X, r.Min.Y, m.X, m.Y)
				if nr.Dx() < 120 {
					nr.Max.X = nr.Min.X + 120
				}
				if nr.Dy() < 60 {
					nr.Max.Y = nr.Min.Y + 60
				}
			} else {
				min := draw.Point{X: m.X - grab.X, Y: m.Y - grab.Y}
				nr = draw.Rect(min.X, min.Y, min.X+w, min.Y+h)
			}
			// Only bother rio when it would actually change something.
			if abs(nr.Min.X-last.Min.X)+abs(nr.Min.Y-last.Min.Y)+
				abs(nr.Max.X-last.Max.X)+abs(nr.Max.Y-last.Max.Y) < 4 {
				continue
			}
			last = nr
			verb := "move"
			if resize {
				verb = "resize"
			}
			s.wctl(fmt.Sprintf("%s -r %d %d %d %d", verb,
				nr.Min.X, nr.Min.Y, nr.Max.X, nr.Max.Y))

		case <-mc.Resize:
			win, err := s.d.Reattach("/dev", s.win)
			if err != nil {
				return
			}
			s.win = win
			r = s.win.Rect()
			if !resize {
				w, h = r.Dx(), r.Dy()
			}
			s.redraw()
		}
	}
}

func abs(n int32) int32 {
	if n < 0 {
		return -n
	}
	return n
}