// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "Engine/DataAsset.h"
#include "GameplayTagContainer.h"
#include "QuestTypes.h"

#include "QuestDataAsset.generated.h"

class ULevelSequence;
class UTexture2D;

/**
 * One quest, authored as an asset.
 *
 * A quest is a tag, a list of steps and a list of things that have to be true before it can be taken.
 * Everything else about it, the journal entry, the rewards and the conditions on individual steps, hangs
 * off those three, so a quest with no code of its own is a data asset drop and one line of dialogue.
 *
 * Steps are not a state machine. Each one listens to whatever the game already broadcasts for it, so an
 * InteractWith step is satisfied by the same interaction the player performs to open a chest, and two
 * quests watching the same NPC both count the same conversation without either of them owning it.
 */
UCLASS(BlueprintType, PrioritizeCategories = ("Quest", "Objectives", "Requirements", "Rewards"))
class PROJECTELERI_API UQuestDataAsset : public UPrimaryDataAsset
{
	GENERATED_BODY()

public:

	/** Identity of the quest. Every lookup, every requirement and every save entry goes through this
	 *  tag, so it is the one field that has to be filled in. */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Quest", meta = (GameplayTagFilter = "Quests"))
	FGameplayTag QuestTag;

	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Quest")
	FText QuestName;

	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Quest", meta = (MultiLine = true))
	FText QuestDescription;

	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Quest")
	TSoftObjectPtr<UTexture2D> QuestIcon;

	/** The NPC this quest is handed out by. The journal uses it to say who to go back to, and a
	 *  dialogue can ask "do you have anything for me" through it. */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Quest", meta = (ForceInlineRow, Categories = "NpcTags"))
	FGameplayTag QuestGiverTag;

	/** Days the player has to hand the quest in. 0 means it never runs out. */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Quest", meta = (ClampMin = 0))
	int32 DeadlineInDays = 0;

	/**
	 * Cutscenes the quest plays as it changes stage, keyed by the status it moves to.
	 *
	 * A stage a quest enters is a status, so this is what makes a quest able to show its own beat
	 * without any blueprint being involved: the scene under Completed plays the moment the quest is
	 * handed in, and the one under Failed plays when a deadline runs out, which is what makes failing a
	 * quest something the player sees rather than something that happens to the journal.
	 *
	 * The scenes go through UDialogueSceneSubsystem, which is what holds the player still for the
	 * length of the sequence and gives the controls back the moment it stops. One scene at a time is
	 * played, so a quest that changes stage twice in a single frame shows the first scene it asked for
	 * and stays quiet about the second.
	 */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Cutscene")
	TMap<EQuestStatus, TSoftObjectPtr<ULevelSequence>> StatusScenes;

	/** The steps, in the order the journal lists them. */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Objectives", meta = (TitleProperty = "Description"))
	TArray<FQuestObjective> Objectives;

	/** When set, a step starts listening only once the step before it is done. Off by default, so a
	 *  quest that asks for three separate things reads as one list of three rather than as a chain. */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Objectives")
	bool bSequentialObjectives = false;

	/** The items a DeliverItems step asks for are taken out of the inventory at the moment the quest
	 *  is handed in, which is what makes a delivery a delivery. Turn it off for a quest that only
	 *  wants to see the item and give it back. */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Objectives")
	bool bConsumeDeliveredItems = true;

	/** Everything that has to be true before this quest can be offered. A prerequisite quest is one of
	 *  these rather than a field of its own: "the fisherman's request", Completed. */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Requirements", meta = (ExcludeBaseStruct, BaseStruct = "/Script/ProjectEleri.GameEventRequirement"))
	TArray<FInstancedStruct> OfferRequirements;

	/** Checked a second time when the quest is handed in, for a quest whose conditions can lapse
	 *  between finishing the last step and getting back to the giver. */
	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Requirements", meta = (ExcludeBaseStruct, BaseStruct = "/Script/ProjectEleri.GameEventRequirement"))
	TArray<FInstancedStruct> TurnInRequirements;

	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Rewards")
	FQuestRewardBundle Rewards;

	/**
	 * True when everything the quest asks for before it can be taken holds right now.
	 *
	 * TestContext is the player character, the same context the event system hands its requirements, so
	 * a condition written for one system behaves identically in the other.
	 */
	UFUNCTION(BlueprintCallable, BlueprintPure, Category = "Eleri|Quest")
	bool AreOfferRequirementsMet(const UObject* TestContext) const;

	/** Checked when the quest is handed in rather than when it is offered */
	UFUNCTION(BlueprintCallable, BlueprintPure, Category = "Eleri|Quest")
	bool AreTurnInRequirementsMet(const UObject* TestContext) const;

	/** The step with this id, or null. Objective ids are unique inside one quest. */
	const FQuestObjective* FindObjective(FName ObjectiveId) const;

	/** The step with this id and where it sits in Objectives, or INDEX_NONE */
	int32 FindObjectiveIndex(FName ObjectiveId) const;

	/** True when the quest asks the player to hand anything over */
	bool HasDeliverStep() const;

	/** Every step that has to be done for the quest to be handed in. Hidden and optional steps are
	 *  left out, since neither of them can hold a quest back. */
	int32 CountRequiredObjectives() const;

	/** True when the step at Index may run: everything before it is done when the quest asks for its
	 *  steps in order, and it is free to run when it does not. */
	bool IsObjectiveUnlocked(int32 Index, const FQuestRuntimeState& State) const;

	/** The items every finished DeliverItems step is asking for, resolved to what the inventory files
	 *  them under. Empty when there is nothing to hand over. */
	void CollectDeliverables(const FQuestRuntimeState& State, TArray<TPair<FPrimaryAssetId, int32>>& OutItems) const;

	/** Says whether the asset is worth offering at all: a quest with no tag, no steps or a duplicate
	 *  step id would otherwise fail quietly in the middle of a playthrough. */
	bool IsValidQuest(FString& OutError) const;
};