class_name JobRunner
extends Node
## Executes a Job's toils on behalf of a Pawn.
##
## Sits between the Decision layer and the Pawn's physical state.  The
## Decision layer (or a WorkProvider) hands us a Job; we tick through its
## toils one-by-one and fire job_completed when the last toil is done.
##
## Design notes (docs/architecture.md — Pawn AI 5-layer pipeline):
##   - JobRunner is layer 3 of 5.  Don't add control-flow that belongs to
##     Decision (layer 1) or WorkProvider (layer 2) here.
##   - Pawn and Pathfinder are held as untyped vars to avoid class_name
##     registration-order issues between autoloads and scene scripts.
##   - tick() is called from Pawn._on_sim_tick each sim tick.  Never spin
##     render-frame work off this function.
##
## Save / load contract (NON-NEGOTIABLE, Phase 3 acceptance criterion):
##   to_dict() / from_dict() round-trip mid-toil state exactly.  A WALK
##   toil with started=true restores correctly: on the first tick after load
##   the runner sits in the "already started, waiting for walk_completed"
##   branch, so pawn.walk_along_path() is NOT called again (which would
##   reset the pawn's progress).  The pawn finishes its own restored walk
##   under its own steam, eventually fires walk_completed, and the toil is
##   marked done.  See _tick_walk() for the branch logic.

signal job_started(job)
signal job_completed(job)

## Untyped — avoids class_name registration-order trap.
var pawn = null
## Untyped — avoids class_name registration-order trap.
var pathfinder = null
## Current Job being executed; null when idle.
var job = null


# ── lifecycle ────────────────────────────────────────────────────────────────

## Wire refs.  Must be called once before any other method.
## Connects pawn.walk_completed → _on_pawn_walk_completed.
func setup(pawn_ref, pathfinder_ref) -> void:
	pawn = pawn_ref
	pathfinder = pathfinder_ref
	pawn.walk_completed.connect(_on_pawn_walk_completed)


# ── public API ───────────────────────────────────────────────────────────────

## Replace the current job (if any) and begin executing the new one.
## Resets nothing on the new job — current_toil_index is used as-is so
## that a restored-from-save job continues from its saved toil position.
func start_job(j) -> void:
	job = j
	Audit.log(
		"job_runner",
		"%s start: %s (%d toils)" % [pawn.pawn_name, j.label, j.toils.size()]
	)
	emit_signal("job_started", j)


## Drop the current job without signalling completion.
## Any walk already in progress is left to finish naturally
## (Phase 3 simplicity; Phase 5+ may add a hard-abort path).
func cancel_job() -> void:
	job = null


## True when a job is currently assigned.
func has_job() -> bool:
	return job != null


# ── sim tick ────────────────────────────────────────────────────────────────

## Called from Pawn._on_sim_tick each sim tick.
## Executes the active toil; advances to the next when it is done;
## emits job_completed when the last toil completes.
func tick() -> void:
	if job == null:
		return

	var t = job.active_toil()
	if t == null:
		_emit_complete()
		return

	match t.kind:
		Toil.KIND_WALK:
			_tick_walk(t)
		Toil.KIND_WAIT:
			_tick_wait(t)
		Toil.KIND_IDLE:
			pass  # Never completes on its own — Decision or player overrides.
		Toil.KIND_INTERACT:
			_tick_interact(t)
		Toil.KIND_BUILD:
			_tick_build(t)
		Toil.KIND_PICKUP:
			_tick_pickup(t)
		Toil.KIND_DEPOSIT:
			_tick_deposit(t)
		Toil.KIND_CRAFT:
			_tick_craft(t)

	if t.done:
		job.advance()
		if job.is_complete():
			_emit_complete()


# ── save / load ──────────────────────────────────────────────────────────────

## Serialise the runner's persistent state.
## {"job": <dict or null>}
func to_dict() -> Dictionary:
	return {
		"job": job.to_dict() if job != null else null,
	}


## Restore from a dict produced by to_dict().
## If the "job" key holds a Dictionary, reconstructs a Job via Job.from_dict().
func from_dict(d: Dictionary) -> void:
	var job_data = d.get("job", null)
	if job_data is Dictionary:
		job = Job.from_dict(job_data)


# ── signal handlers ──────────────────────────────────────────────────────────

## Fired by the Pawn when it finishes walking its path.
## Marks the active WALK toil done so the next tick() advances past it.
## Does NOT call job.advance() directly — tick() handles that.
func _on_pawn_walk_completed() -> void:
	if job == null:
		return
	var t = job.active_toil()
	if t != null and t.kind == Toil.KIND_WALK:
		t.done = true


# ── toil executors ──────────────────────────────────────────────────────────

## Execute one tick of a WALK toil.
##
## On the FIRST tick (started=false):
##   - If the pawn is already at the destination, complete immediately.
##   - Otherwise ask the pathfinder for a route.  If unreachable, log and
##     complete (skip-and-continue; the WorkProvider is responsible for
##     vetting reachability before issuing the job).
##   - Hand the path to the pawn and mark started=true.  From now on this
##     function is a no-op — we just wait for the walk_completed signal.
##
## On SUBSEQUENT ticks (started=true):
##   - No-op.  The pawn walks under its own steam.
##
## After LOAD (started=true from saved state):
##   - Same as subsequent ticks — pawn restores its own path and fires
##     walk_completed when it arrives.  We do NOT call walk_along_path again.
func _tick_walk(t) -> void:
	if not t.data.get("started", false):
		var dest: Vector2i = t.get_walk_destination()
		if pawn.tile == dest:
			t.done = true
			return
		var path: Array[Vector2i] = pathfinder.find_path(pawn.tile, dest)
		if path.is_empty():
			Audit.log(
				"job_runner",
				"%s unreachable: %s → %s" % [pawn.pawn_name, pawn.tile, dest]
			)
			t.done = true
			return
		pawn.walk_along_path(path)
		t.data["started"] = true


## Execute one tick of a WAIT toil.
## Decrements the counter; sets done when it reaches zero.
func _tick_wait(t) -> void:
	t.data["ticks_remaining"] -= 1
	if t.data["ticks_remaining"] <= 0:
		t.done = true


## Execute one tick of an INTERACT toil.
##
## First tick: resolve the target node from the stored NodePath string.
## If the target is gone or freed, log and skip immediately (done=true).
## Otherwise mark started and log the action start.
##
## Every subsequent tick: call tick_method on the target.  After the call,
## check whether the target has been consumed (is_choppable/is_mineable
## returns false, or the node was freed).  If so, mark done.
func _tick_interact(t) -> void:
	var target_path := NodePath(t.data.get("target", ""))
	var target = get_tree().get_root().get_node_or_null(target_path)

	if not t.data.get("started", false):
		if target == null or not is_instance_valid(target):
			Audit.log(
				"job_runner",
				"%s interact target gone — skipping" % pawn.pawn_name
			)
			t.done = true
			return
		t.data["started"] = true
		Audit.log(
			"job_runner",
			"%s interact start: %s.%s" % [pawn.pawn_name, target.name, t.data.get("tick_method", "")]
		)

	# Re-resolve each tick in case the node was freed between ticks.
	target = get_tree().get_root().get_node_or_null(target_path)
	if target == null or not is_instance_valid(target):
		t.done = true
		return

	target.call(StringName(t.data.get("tick_method", "")))

	# Re-check validity after the call (the call may have freed the node).
	if target == null or not is_instance_valid(target):
		t.done = true
		return
	if target.has_method("is_choppable") and not target.is_choppable():
		Audit.log("job_runner", "%s interact done: %s chopped" % [pawn.pawn_name, target.name])
		t.done = true
		return
	if target.has_method("is_mineable") and not target.is_mineable():
		Audit.log("job_runner", "%s interact done: %s mined" % [pawn.pawn_name, target.name])
		t.done = true


## Execute one tick of a BUILD toil.
##
## Mirrors _tick_interact's pattern, but drives construction entities (Wall,
## Floor, Door) via on_build_tick() / is_buildable() instead of on_chop_tick()
## / is_choppable(). The site is "done" (toil complete) when is_buildable()
## returns false — meaning the entity finished building OR was removed.
##
## First tick: resolve target from NodePath. If already gone, skip immediately.
## Every subsequent tick: call on_build_tick() then check is_buildable(). Once
## false the site is built (or cancelled); mark toil done.
func _tick_build(t) -> void:
	var target_path := NodePath(t.data.get("target", ""))
	var target = get_tree().get_root().get_node_or_null(target_path)

	if not t.data.get("started", false):
		if target == null or not is_instance_valid(target):
			Audit.log(
				"job_runner",
				"%s build target gone — skipping" % pawn.pawn_name
			)
			t.done = true
			return
		t.data["started"] = true
		Audit.log(
			"job_runner",
			"%s build start: %s" % [pawn.pawn_name, target.name]
		)

	# Re-resolve each tick in case the node was freed between ticks.
	target = get_tree().get_root().get_node_or_null(target_path)
	if target == null or not is_instance_valid(target):
		t.done = true
		return

	target.on_build_tick()

	# Re-check after the call (on_build_tick may complete + free the ghost state).
	if target == null or not is_instance_valid(target):
		t.done = true
		return
	if target.has_method("is_buildable") and not target.is_buildable():
		Audit.log(
			"job_runner",
			"%s build done: %s" % [pawn.pawn_name, target.name]
		)
		t.done = true


## Execute one tick of a PICKUP toil.
##
## Finds the first unheld Item at pawn.tile in World.items.
## Transfers it into pawn.carried_item via set_being_carried(true).
## Completes in a single tick.
func _tick_pickup(t) -> void:
	var item = null
	for it in World.items:
		if it.tile == pawn.tile and not it.being_carried:
			item = it
			break
	if item == null:
		Audit.log(
			"job_runner",
			"%s pickup: no item at %s" % [pawn.pawn_name, pawn.tile]
		)
		t.done = true
		return
	pawn.carried_item = item
	item.set_being_carried(true)
	Audit.log(
		"job_runner",
		"%s pickup: %s ×%d" % [pawn.pawn_name, item.item_type, item.stack_size]
	)
	t.done = true


## Execute one tick of a DEPOSIT toil.
##
## Places pawn.carried_item at pawn.tile (pixel-centred in the 16 px grid).
## Clears pawn.carried_item. Completes in a single tick.
func _tick_deposit(t) -> void:
	if pawn.carried_item == null:
		Audit.log(
			"job_runner",
			"%s deposit: nothing to deposit" % pawn.pawn_name
		)
		t.done = true
		return
	var item = pawn.carried_item
	item.tile = pawn.tile
	item.position = Vector2(pawn.tile.x * 16 + 8, pawn.tile.y * 16 + 8)
	item.set_being_carried(false)
	pawn.carried_item = null
	# Phase 4: clear the haul-dirty flag — item has landed at its destination.
	# The periodic sweep_for_better_destinations will re-mark it if a higher-
	# priority destination opens up later.
	World.clear_item_haul_flag(item)
	# Phase 5: if the destination tile is covered by a Crate (single-tile
	# container), register the item into the crate's contents. StockpileZone
	# doesn't need this — its items just live at the floor tile.
	var dest = World.stockpile_at_tile(pawn.tile)
	if dest != null and dest.has_method("register_item"):
		dest.register_item(item)
	Audit.log(
		"job_runner",
		"%s deposit: %s ×%d at %s" % [pawn.pawn_name, item.item_type, item.stack_size, pawn.tile]
	)
	t.done = true


## Execute one tick of a CRAFT toil.
##
## First tick (started=false):
##   - Resolves the Workbench node from the stored NodePath. Missing → skip.
##   - Looks up the Bill at data["bill_index"]. Out-of-range → skip.
##   - Validates pawn position matches workbench.tile. Mismatch → skip.
##   - Validates pawn is carrying the correct ingredient type. Missing → skip.
##   - Calls wb.begin_craft(bill) to register the active bill + reset progress.
##   - Marks started=true and logs the craft start.
##
## Every tick (including first, after the checks above):
##   - Calls wb.tick_craft() which increments current_work_progress and returns
##     true when bill.recipe.work_ticks is reached.
##   - On completion:
##       * Consumes the carried ingredient (queue_free + clear pawn slot).
##       * Rolls quality via QualityCalc.roll() using the pawn's skill level.
##       * Spawns an Item scene child of wb.get_parent() at wb.tile.
##       * Calls wb.on_craft_complete() (records bill completion + resets state).
##       * Logs the result and marks toil done.
func _tick_craft(t) -> void:
	var wb_path := NodePath(t.data.get("workbench", ""))
	var wb = get_tree().get_root().get_node_or_null(wb_path)

	if not t.data.get("started", false):
		# ── first-tick validation ─────────────────────────────────────────────
		if wb == null or not is_instance_valid(wb):
			Audit.log("job_runner", "%s craft: workbench gone — skipping" % pawn.pawn_name)
			t.done = true
			return

		var bill_index: int = int(t.data.get("bill_index", -1))
		if bill_index < 0 or bill_index >= wb.bills.size():
			Audit.log(
				"job_runner",
				"%s craft: invalid bill_index %d — skipping" % [pawn.pawn_name, bill_index]
			)
			t.done = true
			return

		var bill = wb.bills[bill_index]

		if pawn.tile != wb.tile:
			Audit.log(
				"job_runner",
				"%s not at workbench (pawn=%s wb=%s) — skipping" % [pawn.pawn_name, pawn.tile, wb.tile]
			)
			t.done = true
			return

		if pawn.carried_item == null or pawn.carried_item.item_type != bill.recipe.ingredient_type:
			Audit.log(
				"job_runner",
				"%s craft: wrong or missing ingredient — skipping" % pawn.pawn_name
			)
			t.done = true
			return

		# Register the bill with the workbench and reset its progress counter.
		wb.begin_craft(bill)
		t.data["started"] = true
		Audit.log("job_runner", "%s craft start: %s" % [pawn.pawn_name, bill.recipe.label])

	# ── per-tick progress ─────────────────────────────────────────────────────
	# Re-resolve each tick in case the workbench was freed between ticks.
	wb = get_tree().get_root().get_node_or_null(wb_path)
	if wb == null or not is_instance_valid(wb):
		t.done = true
		return

	# tick_craft() advances the progress counter and returns true when done.
	var craft_done: bool = wb.tick_craft()
	if not craft_done:
		return  # Still working — toil remains active.

	# ── craft complete ────────────────────────────────────────────────────────

	# Retrieve the bill now (before on_craft_complete clears current_bill).
	var bill_index: int = int(t.data.get("bill_index", -1))
	if bill_index < 0 or bill_index >= wb.bills.size():
		# Guard against the workbench mutating bills mid-craft.
		wb.on_craft_complete()
		t.done = true
		return
	var bill = wb.bills[bill_index]

	# Consume ingredient.
	var ingredient = pawn.carried_item
	pawn.carried_item = null
	if ingredient != null and is_instance_valid(ingredient):
		ingredient.queue_free()

	# Roll quality based on pawn skill for this recipe.
	var skill_level: int = pawn.get_skill(bill.recipe.required_skill)
	var quality: int = QualityCalc.roll(skill_level)

	# Spawn output Item as a sibling of the workbench (World scene level).
	var item_scene: PackedScene = load("res://scenes/entities/item.tscn")
	var output_item = item_scene.instantiate()
	wb.get_parent().add_child(output_item)
	output_item.setup(bill.recipe.output_type, 1, wb.tile)
	output_item.quality = quality

	# Record completion on the bill and reset workbench state.
	wb.on_craft_complete()

	Audit.log(
		"job_runner",
		"%s crafted %s ×1 quality=%s at %s" % [
			pawn.pawn_name,
			bill.recipe.output_type,
			Item.Quality.keys()[quality],
			wb.tile,
		]
	)
	t.done = true


# ── helpers ──────────────────────────────────────────────────────────────────

## Emit job_completed, log, and clear the job reference.
func _emit_complete() -> void:
	var completed = job
	job = null
	Audit.log(
		"job_runner",
		"%s done: %s" % [pawn.pawn_name, completed.label]
	)
	emit_signal("job_completed", completed)