/obj/item/skillchip
	name = "skillchip"
	desc = "This biochip integrates with user's brain to enable mastery of specific skill. Consult certified Nanotrasen neurosurgeon before use."

	icon = 'icons/obj/devices/circuitry_n_data.dmi'
	icon_state = "skillchip"
	custom_price = PAYCHECK_CREW * 3
	w_class = WEIGHT_CLASS_SMALL

	/// Traits automatically granted by this chip, optional. Lazylist.
	var/list/auto_traits
	/// Skill name shown on UI
	var/skill_name
	/// Skill description shown on UI
	var/skill_description
	/// Category string. Used alongside SKILLCHIP_RESTRICTED_CATEGORIES flag to make a chip incompatible with chips from another category.
	var/chip_category = SKILLCHIP_CATEGORY_GENERAL
	/// List of any incompatible categories.
	var/list/incompatibility_list
	/// Fontawesome icon show on UI, list of possible icons https://fontawesome.com/icons?d=gallery&m=free
	var/skill_icon = "brain"
	/// Message shown when activating the chip
	var/activate_message
	/// Message shown when deactivating the chip
	var/deactivate_message
	//If set to FALSE, trying to extract the chip will destroy it instead
	var/removable
	/// How complex the skillchip is. Brains can only handle so much complexity at once and skillchips will start to deactivate when the brain's complexity limit is exceeded.
	var/complexity = 1
	/// How many slots taken up in the brain by this chip. Max brain slots are hard set and should not be changed at all.
	var/slot_use = 1
	/// Variable for flags. DANGEROUS - Child types overwrite flags instead of adding to them. If you change this, make sure all child types have the appropriate flags set too.
	var/skillchip_flags = NONE
	/// Cooldown before the skillchip can be extracted after it has been implanted.
	var/cooldown = 5 MINUTES
	/// Cooldown for chip actions.
	COOLDOWN_DECLARE(chip_cooldown)
	/// Used to determine if this is an abstract type or not.
	/// If this is meant to be an abstract type, set it to the type's path.
	/// Will be overridden by subsequent abstract parents.
	var/abstract_parent_type = /obj/item/skillchip
	/// Set to TRUE when the skill chip's effects are applied. Set to FALSE when they're not.
	var/active = FALSE
	/// Brain that holds this skillchip.
	var/obj/item/organ/brain/holding_brain

/obj/item/skillchip/Initialize(mapload, is_removable = TRUE)
	. = ..()
	removable = is_removable

///We don't grant actions outside of being activated when implanted
/obj/item/skillchip/item_action_slot_check(slot, mob/user, datum/action/action)
	return FALSE

/**
 * Activates the skillchip, if possible.
 *
 * Returns a message containing the reason if activation is not possible.
 * Arguments:
 * * silent - Boolean. Whether or not an activation message should be shown to the user.
 * * force - Boolean. Whether or not to just force de-activation if it would be prevented for any reason.
 */
/obj/item/skillchip/proc/try_activate_skillchip(silent = FALSE, force = FALSE)
	// Should not happen. Holding brain is destroyed and the chip hasn't had its state set appropriately.
	if(QDELETED(holding_brain))
		stack_trace("Skillchip's owner is null or qdeleted brain.")
		return "Skillchip cannot detect viable brain."

	// Also should not happen. We're somehow activating skillchips in a bodyless brain.
	if(QDELETED(holding_brain.owner))
		stack_trace("Skillchip's brain has no owner, owner is null or owner qdeleted.")
		return "Skillchip cannot detect viable body."

	// We have a holding brain, the holding brain has an owner. If we're forcing this, do it hard and fast.
	if(force)
		on_activate(holding_brain.owner, silent)
		return

	// Is the chip still experiencing a cooldown period?
	if(!COOLDOWN_FINISHED(src, chip_cooldown))
		return "Skillchip is still recharging for [COOLDOWN_TIMELEFT(src, chip_cooldown) * 0.1]s"

	// So, we have a brain and that brain has a body. Let's start checking for incompatibility.
	var/activate_msg = has_activate_incompatibility(holding_brain)

	// If there's an activate_msg it means we can't activate for some reason. Return the feedback message.
	if(activate_msg)
		return activate_msg

	// Either there's no incompatibility or we're forcing the activation. We're good to go!
	on_activate(holding_brain.owner, silent)

/**
 * Deactivates the skillchip, if possible.
 *
 * Returns a message containing the reason if deactivation is not possible.
 * Arguments:
 * * silent - Boolean. Whether or not an activation message should be shown to the user.
 * * force - Boolean. Whether or not to just force de-activation if it would be prevented for any reason.
 * * brain_owner - the owner var of the brain is set to null on organ/on_mob_remove(), so we need this if owner is null.
 */
/obj/item/skillchip/proc/try_deactivate_skillchip(silent = FALSE, force = FALSE, mob/living/brain_owner)
	if(!active)
		return "Skillchip is not active."

	// Should not happen. Holding brain is destroyed and the chip hasn't had its state set appropriately.
	if(!holding_brain)
		stack_trace("Skillchip doesn't have a holding brain.")
		return "Skillchip cannot detect viable brain."

	if(!brain_owner)
		brain_owner = holding_brain.owner
	// Also should not happen. We're somehow deactivating skillchips in a bodyless brain.
	if(QDELETED(brain_owner))
		active = FALSE
		stack_trace("Skillchip's brain has no owner, owner is null or owner qdeleted.")
		return "Skillchip cannot detect viable body."

	// We have a holding brain, the holding brain has an owner. If we're forcing this, do it hard and fast.
	if(force)
		on_deactivate(brain_owner, silent)
		return

	// Is the chip still experiencing a cooldown period?
	if(!COOLDOWN_FINISHED(src, chip_cooldown))
		return "Skillchip is still recharging for [COOLDOWN_TIMELEFT(src, chip_cooldown) * 0.1]s"

	// We're good to go. Deactive this chip.
	on_deactivate(brain_owner, silent)

/**
 * Called when a skillchip is inserted in a user's brain.
 *
 * Arguments:
 * * owner_brain - The brain that this skillchip was implanted in to.
 */
/obj/item/skillchip/proc/on_implant(obj/item/organ/brain/owner_brain)
	SHOULD_CALL_PARENT(TRUE)
	if(holding_brain)
		CRASH("Skillchip is trying to be implanted into [owner_brain], but it's already implanted in [holding_brain]")

	holding_brain = owner_brain
	SEND_SIGNAL(src, COMSIG_SKILLCHIP_IMPLANTED, holding_brain)

/**
 * Called when a skillchip is activated.
 *
 * Arguments:
 * * user - The user to apply skillchip effects to.
 * * silent - Boolean. Whether or not an activation message should be shown to the user.
 */
/obj/item/skillchip/proc/on_activate(mob/living/carbon/user, silent=FALSE)
	SHOULD_CALL_PARENT(TRUE)
	if(!silent && activate_message)
		to_chat(user, activate_message)

	if(length(auto_traits))
		user.add_traits(auto_traits, SKILLCHIP_TRAIT)

	active = TRUE

	for(var/datum/action/action as anything in actions)
		action.Grant(user)

	COOLDOWN_START(src, chip_cooldown, cooldown)

/**
 * Called when a skillchip is removed from the user's brain.
 *
 * Always deactivates the skillchip.
 * Arguments:
 * * user - The user to remove skillchip effects from.
 * * silent - Boolean. Whether or not a deactivation message should be shown to the user.
 */
/obj/item/skillchip/proc/on_removal(silent=FALSE)
	if(active)
		try_deactivate_skillchip(silent, TRUE)

	COOLDOWN_RESET(src, chip_cooldown)
	SEND_SIGNAL(src, COMSIG_SKILLCHIP_REMOVED, holding_brain)
	holding_brain = null

/**
 * Called when a skillchip is deactivated.
 *
 * Arguments:
 * * user - The user to remove skillchip effects from.
 * * silent - Boolean. Whether or not a deactivation message should be shown to the user.
 */
/obj/item/skillchip/proc/on_deactivate(mob/living/carbon/user, silent=FALSE)
	SHOULD_CALL_PARENT(TRUE)
	if(!silent && deactivate_message)
		to_chat(user, deactivate_message)

	if(length(auto_traits))
		user.remove_traits(auto_traits, SKILLCHIP_TRAIT)

	active = FALSE

	for(var/datum/action/action as anything in actions)
		action.Remove(user)

	COOLDOWN_START(src, chip_cooldown, cooldown)

/**
 * Checks whether a given skillchip has an incompatibility with a brain that should render it impossible
 * to activate.
 *
 * Returns a string with an explanation if the chip is not activatable. FALSE otherwise.
 * Arguments:
 * * skillchip - The skillchip you're intending to activate. Does not activate the chip.
 */
/obj/item/skillchip/proc/has_activate_incompatibility(obj/item/organ/brain/brain)
	if(QDELETED(brain))
		return "No brain detected."

	// Check if there's enough complexity usage left to activate the skillchip.
	var/max_complexity = brain.get_max_skillchip_complexity()
	var/new_complexity = brain.get_used_skillchip_complexity() + get_complexity()
	if(new_complexity > max_complexity)
		return "Skillchip is too complex to activate: [new_complexity] total out of [max_complexity] max complexity."

	return FALSE


/**
 * Checks for skillchip incompatibility with another chip.
 *
 * Does *this* skillchip have incompatibility with the skillchip in the args?
 * Override this with any snowflake chip-vs-chip incompatibility checks.
 * Returns a string with an incompatibility explanation if the chip is not compatible, returns FALSE
 * if it is compatible.
 * Arguments:
 * * skillchip - The skillchip to test for incompatability.
 */
/obj/item/skillchip/proc/has_skillchip_incompatibility(obj/item/skillchip/skillchip)
	// Only allow multiple copies of a type if SKILLCHIP_ALLOWS_MULTIPLE flag is set
	if(!(skillchip_flags & SKILLCHIP_ALLOWS_MULTIPLE) && (skillchip.type == type))
		return "Duplicate chip detected: [skillchip.name]"

	// Prevent implanting multiple chips of the same category.
	if((skillchip_flags & SKILLCHIP_RESTRICTED_CATEGORIES) && (skillchip.chip_category in incompatibility_list))
		return "Incompatible with implanted [skillchip.chip_category] chip [skillchip.name]."

	return FALSE

/**
 * Performs a full sweep of checks that dictate if this chip can be implanted in a given target.
 *
 * Override this with any snowflake chip checks. An example of which would be checking if a target is
 * mindshielded if you've got a special security skillchip.
 * Returns a string with an incompatibility explanation if the chip is not compatible, returns FALSE
 * if it is compatible.
 * Arguments:
 * * target - The mob to check for implantability with.
 */
/obj/item/skillchip/proc/has_mob_incompatibility(mob/living/carbon/target)
	// No carbon/carbon of incorrect type
	if(!istype(target))
		return "Incompatible lifeform detected."

	// No brain
	var/obj/item/organ/brain/brain = target.get_organ_slot(ORGAN_SLOT_BRAIN)
	if(QDELETED(brain))
		return "No brain detected."

	// Check brain incompatibility. This also performs skillchip-to-skillchip incompatibility checks.
	var/brain_message = has_brain_incompatibility(brain)
	if(brain_message)
		return brain_message

	return FALSE

/**
 * Performs a full sweep of checks that dictate if this chip can be implanted in a given brain.
 *
 * Override this with any snowflake chip checks.
 * Returns TRUE if the chip is fully compatible, FALSE otherwise.
 * Arguments:
 * * brain - The brain to check for implantability with.
 */
/obj/item/skillchip/proc/has_brain_incompatibility(obj/item/organ/brain/brain)
	if(!istype(brain))
		stack_trace("Attempted to check incompatibility with invalid brain object [brain].")
		return "Incompatible brain."

	var/chip_message

	// Slot capacity check!
	var/max_slots = brain.get_max_skillchip_slots()
	var/used_slots = brain.get_used_skillchip_slots()

	if(used_slots + slot_use > max_slots)
		return "Not enough free slots. You have [max_slots - used_slots] free and need [slot_use]."

	// Check if this chip is incompatible with any other chips in the brain.
	for(var/skillchip in brain.skillchips)
		chip_message = has_skillchip_incompatibility(skillchip)
		if(chip_message)
			return chip_message

	return FALSE

/**
 * Returns whether the chip is on cooldown. Chips ordinarily go on cooldown when activated.
 *
 * This does not mean the chip should be impossible to do anything with.
 * It's up to each individual piece of code to decide what it does with the result of this proc.
 *
 * Returns TRUE if the chip's extraction cooldown hasn't yet passed.
 */
/obj/item/skillchip/proc/is_on_cooldown()
	return !COOLDOWN_FINISHED(src, chip_cooldown)

/**
 * Returns whether the chip is active.
 *
 * Intended to be overriden.
 * Returns TRUE if the chip is active.
 */
/obj/item/skillchip/proc/is_active()
	return active

/**
 * Returns the chip's complexity.
 *
 * Intended to be overriden.
 */
/obj/item/skillchip/proc/get_complexity()
	return complexity

/**
 * Returns a list of basic chip info. Used by the skill station.
 */
/obj/item/skillchip/proc/get_chip_data()
	return list(
		"name" = skill_name,
		"icon" = skill_icon,
		"desc" = skill_description,
		"complexity" = get_complexity(),
		"slot_use" = slot_use,
		"removable" = removable,
		"ref" = REF(src),
		"active" = is_active(),
		"active_error" = has_activate_incompatibility(holding_brain),
		"cooldown" = COOLDOWN_TIMELEFT(src, chip_cooldown),
		"actionable" = is_on_cooldown())

/**
 * Gets key metadata from this skillchip in an assoc list.
 *
 * If you override this proc, don't forget to also override set_metadata, which takes the output of
 * this proc and uses it to set the metadata.
 * Does not copy over any owner or brain status. Handle that externally.
 */
/obj/item/skillchip/proc/get_metadata()
	var/list/metadata = list()
	metadata["type"] = type
	metadata["chip_cooldown"] = chip_cooldown
	metadata["active"] = active
	metadata["removable"] = removable

	return metadata

/**
 * Sets key metadata for this skillchip from an assoc list.
 *
 * Best used with the output from get_metadata() of another chip.
 * If you override this proc, don't forget to also override get_metadata, which is where you should
 * usually get the assoc list that feeds into this proc.
 * Does not set any owner or brain status. Handle that externally.
 * Arguments:
 * metadata - Ideally the output of another chip's get_metadata proc. Assoc list of metadata.
 */
/obj/item/skillchip/proc/set_metadata(list/metadata)
	var/active_msg
	// Start by trying to activate.
	active = metadata["active"]
	if(active)
		active_msg = try_activate_skillchip(FALSE, TRUE)

	// Whether it worked or not, set the rest of the metadata and then return any activate message.
	chip_cooldown = metadata["chip_cooldown"]
	removable = metadata["removable"]

	return active_msg