package main

import (
    "fmt"
    "log"
    "os"
    "os/exec"

    "github.com/jezek/xgb"
    "github.com/jezek/xgb/xproto"
)

// TODO: Make a separate keysym file and fully populate it.
const (
    XK_q      = 0x0071
    XK_Return = 0xff0d
)

func main() {
    fmt.Println("ILLI: Execution begins")

    xconn := connectToXServer()
    attachedScreens := getAttachedScreens(xconn)
    xroot := getXRoot(xconn)
    keymap := getKeyboardMap(xconn)
    registerForKeyEvents(xconn, xroot, keymap)

    becomeWM(xconn, xroot)

    // Build a list of windows needing management ------------------------------

    if len(attachedScreens) > 0 {
        fmt.Println("The Go compiler is waaaaay too picky about unused variables...")
    }

    tree, err := xproto.QueryTree(xconn, xroot.Root).Reply()
    if err != nil {
        log.Fatal(err)
    }
    if tree != nil {
        //workspaces = make(map[string]*Workspace)
        //defaultw := &Workspace{mu: &sync.Mutex{}}
        for _, c := range tree.Children {
            if isMappedWindow(xconn, c) {
//                err := defaultw.Add(c)
//                if err != nil {
//                    log.Println(err)
//                }
                fmt.Println("ILLI: Found a client.")
            }

        }

//        if len(attachedScreens) > 0 {
//            defaultw.Screen = &attachedScreens[0]
//        }
//
//        workspaces["default"] = defaultw
//
//        if err := defaultw.TileWindows(); err != nil {
//            log.Println(err)
//        }

    }

    // Main program loop reacts to X events ------------------------------------

eventloop:
    for {
        xevent, err := xconn.WaitForEvent()
        if err != nil {
            log.Println(err)
            continue
        }
        switch e := xevent.(type) {
            case xproto.KeyPressEvent:
                if err := handleKeyPressEvent(keymap, e); err != nil {
                    break eventloop
                }
            default:
                log.Println(xevent)
        }
    }
}

// The client list appears to have some entries for windows that shouldn't
// actually be viewable. For now, it appears that only windows with a
// `MapState` value of 2 should be viewable. TODO: Verify this.
//   - https://github.com/BurntSushi/xgb/blob/master/xproto/xproto.go#L3772
//   - https://github.com/BurntSushi/xgb/blob/master/xproto/xproto.go#L10287
func isMappedWindow(conn *xgb.Conn, windowID xproto.Window) bool {
    reply, err := xproto.GetWindowAttributes(conn, windowID).Reply()
    if err != nil {
        log.Fatal(err)
    }
    if reply != nil && reply.MapState == 2 {
        return true
    }
    return false
}

// TODO: Determine how I want to split the main event loop from the various
// event handlers (like this keypress handler). It shouldn't grow too
// fragmented, nor should it grow into a monolithic beast, but the balance
// needs to be selected after the handlers are built out more completely.
func handleKeyPressEvent(keymap [256][]xproto.Keysym, key xproto.KeyPressEvent) error {
    switch keymap[key.Detail][0] {
        case XK_q:
            switch key.State {
                case xproto.ModMask1 | xproto.ModMaskShift:
                    // TODO: Where and how do I want to handle exit/restart?
                    // -------------------------
                    // We must manually close the X connection since we used
                    // `defer` when setting it up and os.Exit() short-circuits
                    // that deferral.
                    //xc.Close()
                    os.Exit(0)
            }
        case XK_Return:
            switch key.State {
                case xproto.ModMask1 | xproto.ModMaskShift:
                    cmd := exec.Command("xterm")
                    err := cmd.Start()
                    if err != nil {
                        log.Fatal(err)
                    }
            }
        default:
            return nil
    }
    return nil // TODO: What do I actually want to return here?
}