package game

// daemon.c — the daemon/fuse scheduler.
//
// C identifies daemons and fuses by function pointer; the port uses DaemonID
// (which the C save format itself resorted to when serializing d_list), and
// dispatches through one switch in daemons.go.

// DaemonID names a daemon/fuse callback. The numeric values match the
// function-pointer-to-int mapping in state.c rs_write_daemons.
type DaemonID int

// Daemon and fuse callback identifiers. The first block's numeric values
// match the function-pointer-to-int mapping in state.c rs_write_daemons;
// the second block covers fuses state.c never saved (the Go save format
// handles them all uniformly).
const (
	DNone      DaemonID = 0
	DRollwand  DaemonID = 1
	DDoctor    DaemonID = 2
	DStomach   DaemonID = 3
	DRunners   DaemonID = 4
	DSwander   DaemonID = 5
	DNohaste   DaemonID = 6
	DUnconfuse DaemonID = 7
	DUnsee     DaemonID = 8
	DSight     DaemonID = 9
	DVisuals   DaemonID = 10
	DComeDown  DaemonID = 11
	DLand      DaemonID = 12
	DTurnSee   DaemonID = 13 // potions.c casts turn_see to a fuse callback
)

// Scheduling phases and slot states (daemon.c).
const (
	dEmpty     = 0
	Before     = 1  // run before the player's command
	After      = 2  // run after the player's command
	daemonTime = -1 // d_time sentinel: a recurring daemon, not a fuse
)

// delayedAction is rogue.h struct delayed_action.
type delayedAction struct {
	Type int // dEmpty, Before or After
	Func DaemonID
	Arg  int
	Time int // daemonTime for daemons; remaining turns for fuses
}

// DaemonList is the C d_list[MAXDAEMONS] plus the file statics that ride
// along with the daemon system.
type DaemonList struct {
	List    [MaxDaemons]delayedAction
	Between int // daemons.c rollwand static `between`
}

// dSlot finds an empty slot in the daemon/fuse list (daemon.c d_slot).
func (g *RogueGame) dSlot() *delayedAction {
	for i := range g.Daemons.List {
		if g.Daemons.List[i].Type == dEmpty {
			return &g.Daemons.List[i]
		}
	}

	panic("ran out of fuse slots") // C: debug message in MASTER, NULL deref otherwise
}

// findSlot finds a particular slot in the table (daemon.c find_slot).
func (g *RogueGame) findSlot(f DaemonID) *delayedAction {
	for i := range g.Daemons.List {
		d := &g.Daemons.List[i]
		if d.Type != dEmpty && d.Func == f {
			return d
		}
	}

	return nil
}

// StartDaemon starts a recurring daemon (daemon.c start_daemon).
func (g *RogueGame) StartDaemon(f DaemonID, arg, typ int) {
	dev := g.dSlot()
	dev.Type = typ
	dev.Func = f
	dev.Arg = arg
	dev.Time = daemonTime
}

// KillDaemon removes a daemon from the list (daemon.c kill_daemon).
func (g *RogueGame) KillDaemon(f DaemonID) {
	if dev := g.findSlot(f); dev != nil {
		dev.Type = dEmpty
	}
}

// DoDaemons runs all the daemons that are active with the current flag
// (daemon.c do_daemons).
func (g *RogueGame) DoDaemons(flag int) {
	for i := range g.Daemons.List {
		dev := &g.Daemons.List[i]
		if dev.Type == flag && dev.Time == daemonTime {
			g.runDaemon(dev.Func, dev.Arg)
		}
	}
}

// Fuse starts a countdown fuse (daemon.c fuse).
func (g *RogueGame) Fuse(f DaemonID, arg, time, typ int) {
	wire := g.dSlot()
	wire.Type = typ
	wire.Func = f
	wire.Arg = arg
	wire.Time = time
}

// Lengthen extends a fuse's countdown (daemon.c lengthen).
func (g *RogueGame) Lengthen(f DaemonID, xtime int) {
	if wire := g.findSlot(f); wire != nil {
		wire.Time += xtime
	}
}

// Extinguish puts out a fuse (daemon.c extinguish).
func (g *RogueGame) Extinguish(f DaemonID) {
	if wire := g.findSlot(f); wire != nil {
		wire.Type = dEmpty
	}
}

// DoFuses decrements all fuses in the given phase and fires any that burn
// down (daemon.c do_fuses).
func (g *RogueGame) DoFuses(flag int) {
	for i := range g.Daemons.List {
		wire := &g.Daemons.List[i]
		if wire.Type == flag && wire.Time > 0 {
			wire.Time--
			if wire.Time == 0 {
				wire.Type = dEmpty
				g.runDaemon(wire.Func, wire.Arg)
			}
		}
	}
}